Re: Concentric Guide Bearing Location
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Re: Concentric Guide Bearing Location
?
Hi there group, ?I just picked up a nice little
super in good shape Grizzly G1010 4x6 from a lady
whose husband passed away. ?Got it super cheap.. ?He
was a wood worker and used it to cut wood only. ?The
saw is complete and was kept covered when not in use.
?The only thing that was disassembled was the two
guide bearing assemblies. ?I purchased 6 new 6000z
bearing and installed them on the shafts and saw that
two of them were concentric for adjustment. ?My
question to anyone who can help is where do they go?
If
you are standing in front of the machine looking at
the Grizzly nameplate on the left and motor is on the
right in horizontal cutting position. ?Do they go in
front of the blade or behind? ?Or does one guide get
one on the front and the other guide get one on the
rear of the blade? ?I¡¯m stumped?????? ??Need some help
getting this little metal slicer up and running!!!!
? One on each end , put them both on the same side of the
blade . Then adjust for about .006 - .010 chip clearance between
the blade and guide bearings . There are a couple of good
articles on alignment in the archives unless yahoo has managed
to lose them .
? To the group owner - have you considered moving the group
to IO ? Several other groups I read have made the move , and are
better for it .
? --
? Snag
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Concentric Guide Bearing Location
Hi there group, ?I just picked up a nice little super in good shape Grizzly G1010 4x6 from a lady whose husband passed away. ?Got it super cheap. ?He was a wood worker and used it to cut wood only. ?The saw is complete and was kept covered when not in use. ?The only thing that was disassembled was the two guide bearing assemblies. ?I purchased 6 new 6000z bearing and installed them on the shafts and saw that two of them were concentric for adjustment. ?My question to anyone who can help is where do they go?
If you are standing in front of the machine looking at the Grizzly nameplate on the left and motor is on the right in horizontal cutting position. ?Do they go in front of the blade or behind? ?Or does one guide get one on the front and the other guide get one on the rear of the blade? ?I¡¯m stumped?????? ??Need some help getting this little metal slicer up and running!!!!
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Re: OT: Bainbridge 712 resurrection [4 Attachments]
Just wanted to say thanks again for all the help. Put on a newish spring and it cuts like a dream!! 3/4" rebar. Just a bit of a burrito at the end. Look ma, no hands!! :)
JV,
?A bit more progress today. Added a makeshift tension gauge. Before and after pics attached. Nothing fancy. Just a way to mark the tensioner and return to same relative position. (Simple $5?steel ruler).? Also, I did tension the belt more and gave it a test cut. Happy to report that by holding the tensioner as the blade engages the stock, the saw cuts amazingly well.? So, next challenge, spring tension. I didn't get a luggage scale, yet. However, I did adjust the spring, test, readjust, test, rinse/repeat. Same results. I've attached a couple of pics of this saw's spring setup. I think I'll need to get a new spring.? Lastly, just to show the blade travel. Attached are a couple of pictures of the wheels and blade after my hand held cut. Thoughts? Thanks! Darren
?
[Attachment(s) from Darren McCarley included below]
JV, Fantastic feedback. Thank you! Funny how life works. I wouldn't have understood most of your explanation, if I hadn't worked through the challenges first. I greatly appreciate your time and sharing of knowledge. I'll attempt to respond in a semi-orderly fashion.
Blade tension: I believe I'm still in the "thunk" area of tone. I'm right handed and will tension with my left till I get more of a "twang".?
Wheels: These wheels seem to have a bit of crown and no rims (If I understand you). Perhaps a difference in desing? (Pics attached)
Driven Wheel tilt: Thank you for the in depth explanation on how this works. I'll be modifying the saw to include a simple tension gauge/ruler.
Drive wheel: The fact that this wheel is pinned continues to be a point of concern of mine. It looks like this wheel originally used a set screw. I assume the wheel was slipping on the shaft and someone stripped the threads trying to tighten the screw too much. In an effort to "fix" this mistake, perhaps they drilled and pinned the wheel. Thus negating ALL fore/aft adjustment of the drive wheel. I have a couple of options here.
1) Leave the pin. - HUGE assumption of accuracy and useability.? 2) Drill and tap 3 more holes and use 3 set screws 120¡ã off setting. I could go so far as to measure and flatten parts of the drive shaft to aid in anti-slip, but I REALLY do not want to modify beyond repair. (First, do no harm.) 3) Broach a keyway in the drive wheel and a LONG keyslot in the shaft. Ideal, but much more entailed than I THINK I need.??
* Your thoughts?
Blade: The blade is a Lennox 3/4" blade
Blade guides: The blade side guides are cammed. After a thorough cleaning, I re-installed them and I intentionally opened the gap as far as possible. I ignorantly assumed they may be causing the derailment. I'll readjust them.?
* Am I correct in assuming the use of feeler gauges may be over kill here?? e.g. guide|blade|feeler gauge|guide Where the feeler guage = total clearance/2
Bow weight: EXCELLENT point on the Bow weight. I noticed the heft of the machine when lowering? the frame. I'll look into adjusting the spring. I never thought about using a luggage scale. I'll have to pick one of those up. As fast as the derail happens, and the amount of cutting that occurs just prior to that, I'd be willing to bet a combination of lack of roller guide support and weight is the culprit here. If that's the case, that is awesome. As it seems I'm quite close! Well, close to the next challenge anyway. :)
More to come, and as always, thank you for your feedback! Darren
?
OK this is a long one:? There are 3
adjustment that determine whether a blade will track on any bandsaw: 1.?? Blade tension 2.?? Driven wheel tilt 3.?? Drive wheel position on its axle ? It helps to
understand why these things matter: Bimetal
bandsaw blades are tensioned to 25-30,000psi stress, flexback carbon steel blades to 15-20,000psi.? That means a ?¡± wide bimetal blade, has about 300lb
tension in it when tensioned properly. With a blade run on both sides of the
wheels, that¡¯s 600lb force pulling the bandwheels together.? The sawframe casting flexes, any slack in
bearings is pulled out, and axles and axle supports bend.? You can¡¯t set the tracking properly until you¡¯ve
got the right tension in the blade.??It
takes more than you think; on a 4x6 its about as much as a normal person can wind
the 2?¡± diameter tension knob one handed, without any aids. It makes a real
twang when plucked, not a dull thok.? Don¡¯t
know what it will take on your 712, but if it¡¯s got a ?¡° blade, the tension
will be half as much again as a ?¡± blade. ?You¡¯ll need to decide where full tension is,
before you start tracking (see comments below on how to mark it) ? The drive
lands on the wheels of metal cutting bandsaws are a (very short) parallel cylinder,
not crowned like a wood bandsaw.? The
blade is supposed to run not quite touching both rims. The rims are just
there to make the blade easier to put on, not to track the blade. The drive and
driven wheels and bearings are manufactured to be parallel to each other when there
is no tilt in the driven wheel. ? However,
when there is tension in the blade, the tension pulls the wheels out of parallel
and the blade runs off. To counter this the driven wheel is tilted in at the
top, which makes the blade track toward the rim on both wheels, more strongly
at the driven wheel than on the drive wheel. ? Broadly
speaking, you adjust the tilt so that the back of the blade runs about 1/32¡±
(1mm) away from the rim of the driven wheel and allow the sawband to find its
own place on the bottom rim, then move the bottom rim on its shaft in or out
until the back edge of the blade just doesn¡¯t touch the rim on the drive wheel
when the blade is at full tension. However
there are a number of things to consider while doing this: 1. ??Tracking
is tension dependent; the greater the tension the more the back edge of the
blade moves away from the rim. 2.?? You can¡¯t change the tilt in the driven
wheel without releasing the tension. 3.?? So, you must be able to re-tension the blade
to the same value each time ¨C make a scratch with a scriber on one half of the
tension mechanism and align the top edge of a piece of sticky tape with the
scratch, stuck to the other half of the mechanism. It'll be different when you change blades as each is a slightly different loop length. 4.?? The roller blade guides do affect tracking a
bit (will make it move in about 1/32¡± at top and 1/8¡± on bottom wheel, but its
easier to track the blade without them in place ¨C so remove until you¡¯ve adjusted
the blade to within 1/16¡± at top and 5/32¡± at bottom 5.?? The tracking is very sensitive to movement
of the tilting set-screw. 1/6th turn changes it a lot near the
correct point, less sensitive when just starting to tilt. 6.?? Start with set screw at ¡®no tilt¡¯ position (release
blade tension, undo both bolts, back setscrew out, then tighten both bolts again,
then turn setscrew back in until it touches). 7.?? It¡¯ll need at least ? turn in on set screw
to start with so re-set the tilt with the set-screw half a turn in. 8.?? Tension blade so that the slack is just out
of the blade, (i.e. no-where near full tension), and turn on/off quickly to
see how the blade moves.? If it sits ok,
then keep it running and slowly increase the blade tension and notice how it
starts to move away from the rims. 9.?? If it still wants to move away from the driven
wheel rim at less than full tension, increase the tilt another ? turn of the
set screw each time, then 1/6th turn when you get near full tension,
until the blade tracks ~1/16¡± from the rim of the driven wheel at full tension.? 10.? ?Don't worry about the drive wheel, unless it still derails even when the driven wheel tracks properly, that shows its way too far in on its shaft (N.B. see comment below about gearbox bearing failure) 11.?? Now move the driven wheel on its shaft
until the back edge of the blade is ~5/32¡± from the rim 12.?? Re-install the roller blade guides and see if
the blade tracks just clear (1/32¡±) of the rims.? Will be ok if it looks like its touching, but
you can¡¯t hear any graunching noises (back edge of blade scraping hard on the
rim). ? That¡¯s about
it, though the blade must be welded squarely (watch for uneven gap from back of
blade to rim as the join passes over the driven wheel) and the gearbox output
shaft bearing must be ok (if it¡¯s failed the output shaft will bend as the
tension is increased, so the blade derails from the bottom wheel only, not the top
one).? You have to keep the blade on
before you can judge either of these, so try to make it track as above first.? ? Don¡¯t be
scared to move the drive wheel out, if it keeps derailing from the bottom when
the top seems OK , though you do need to check that the gearbox output bearing
hasn¡¯t failed? (they do it often enough
and it could be the reason why it was sold). I see your drive wheel is pinned,
4x6¡¯s use a key and a set screw, you could use 243 Loctite until you get the
position right, then re-pin it. ?243 Loctite
is weak enough to be able to change the position of the drive wheel with heat
and a gear puller to set the tracking, but even high strength Loctite won¡¯t be
strong enough to drive when cutting metal.
Let us know how you get on - jv
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Re: OT: Bainbridge 712 resurrection
Ralph/John,
Another excellent bit of information on tension. Thanks for the video and the continued conversation!! Sadly, I'll be on business travel until the weekend. Dang work getting in the way all the time. :) At least it gives me a good reason to go hunting for a new spring as I pass a few places that might stock springs on the way to the airport.
All the best,
Darren
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Re: OT: Bainbridge 712 resurrection
Thanks for posting that Ralph.? You can always learn from people like him. Tensioning I went down to the workshop after seeing it, and set up a 10-14 bimetal blade with the load cell spliced into it and tensioned the blade to the midpoint of the manfr stated range for bimetal blades?(25-30,000psi stress).? Then put a small piece of round steel that was a nice sliding fit in the blade guard fixing hole and found the distance at which it first touches, when tapped like he did. Maximum distance between steel piece and blade at 1st hitting was 2mm (5/64").?? Just open the guard and slide the piece of steel up to a feeler gauge set or a bit from any 2mm sheet stock, lock the steel piece with your fingers while sliding the the feeler gauge out, then tap away a few times at each tension setting.? When you hit the steel piece, you'll see it jump away.? It's easier to over-tension and reduce the tension until the tapping hits it.? ? There's reasons it would be different from his recommendation.? The span between the wheels is smaller on a 4x6 and he said "...no more than 1/8" and I presume that includes different blade widths and thicknesses. For a normal 14" wood band saw that's probably significantly tighter than most people would tension their blades.
This is better than ANY of the 4x6 saw manufacturer's methods.? Bear in mind that 2mm is the midpoint of the acceptable tension range, so you're pretty safe with over- and under- 'tapping' it. Good for a 4x6 but I'm not sure that it helps you with your Bainbridge 712 Darren.?
Tracking His recommendations for crowned wheels like Darren's makes sense, though the reliance on the manufacturers setting for the bottom wheel is no help to Darren who suspects its all been changed.? Then co-planar is a good start point I think, as much as he rubbishes it. His recommendations for side roller setting don't specifically apply to a 4x6 since our guides twist the blade. I've not found the rear support roller setting to be critical like he does.? I run mine just clear for most of the rotation of the blade, but the welds vary so much the back of the blade moves around quite a lot.? You just don't want the back support rollers set too far forward.?I once found, when mine were set ~1/4" too far forward by mistake, the weight of the sawframe used the back support roller (esp the lower one) as a pivot to de-rail the blade.? If the blade is close to the rim on the bandwheels and the back support rollers are 0~1/32" (0~1mm) clear, then the sawframe weight will push the blade back against the rollers without deflecting the teeth sideways at all - jv
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Re: OT: Bainbridge 712 resurrection
I like to say nothing of how he folds the blades.
Ralph
?
Yes the small rule will do nicely, but you need to write the setting down. Spirit marker on the frame somewhere (or whiteboard marker if you can guarantee not to rub it off before you need to know it again). It changes with every different blade, which is why I use a tab of sticky tape. The pivot arm, that the counterbalance spring attaches to on a 4x6, is only 60mm long from pivot to spring retainer bolt, so the spring is very strong.? Your head is heavier so maybe a spring from Harbor Freight's spare parts dept would be better than the one you've got.? You could slide the top mount of the spring inward toward the pivot point to reduce the tension in the spring and adjust bow weight. You don't have to have an extension balance, like the luggage weigh scale, to find the bow weight.? If you've got kitchen (or maybe bathroom) scales you can rest the head of the saw frame casting on it.? Just have to arrange that the weight presses roughly in the middle of the scales (maybe a short stick?). Looks like you've got it under control - jv
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Re: OT: Bainbridge 712 resurrection [4 Attachments]
Yes the small rule will do nicely, but you need to write the setting down. Spirit marker on the frame somewhere (or whiteboard marker if you can guarantee not to rub it off before you need to know it again). It changes with every different blade, which is why I use a tab of sticky tape. The pivot arm, that the counterbalance spring attaches to on a 4x6, is only 60mm long from pivot to spring retainer bolt, so the spring is very strong.? Your head is heavier so maybe a spring from Harbor Freight's spare parts dept would be better than the one you've got.? You could slide the top mount of the spring inward toward the pivot point to reduce the tension in the spring and adjust bow weight. You don't have to have an extension balance, like the luggage weigh scale, to find the bow weight.? If you've got kitchen (or maybe bathroom) scales you can rest the head of the saw frame casting on it.? Just have to arrange that the weight presses roughly in the middle of the scales (maybe a short stick?). Looks like you've got it under control - jv
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Re: OT: Bainbridge 712 resurrection [4 Attachments]
JV,
?A bit more progress today. Added a makeshift tension gauge. Before and after pics attached. Nothing fancy. Just a way to mark the tensioner and return to same relative position. (Simple $5?steel ruler).? Also, I did tension the belt more and gave it a test cut. Happy to report that by holding the tensioner as the blade engages the stock, the saw cuts amazingly well.? So, next challenge, spring tension. I didn't get a luggage scale, yet. However, I did adjust the spring, test, readjust, test, rinse/repeat. Same results. I've attached a couple of pics of this saw's spring setup. I think I'll need to get a new spring.? Lastly, just to show the blade travel. Attached are a couple of pictures of the wheels and blade after my hand held cut. Thoughts? Thanks! Darren
?
[Attachment(s) from Darren McCarley included below]
JV, Fantastic feedback. Thank you! Funny how life works. I wouldn't have understood most of your explanation, if I hadn't worked through the challenges first. I greatly appreciate your time and sharing of knowledge. I'll attempt to respond in a semi-orderly fashion.
Blade tension: I believe I'm still in the "thunk" area of tone. I'm right handed and will tension with my left till I get more of a "twang".?
Wheels: These wheels seem to have a bit of crown and no rims (If I understand you). Perhaps a difference in desing? (Pics attached)
Driven Wheel tilt: Thank you for the in depth explanation on how this works. I'll be modifying the saw to include a simple tension gauge/ruler.
Drive wheel: The fact that this wheel is pinned continues to be a point of concern of mine. It looks like this wheel originally used a set screw. I assume the wheel was slipping on the shaft and someone stripped the threads trying to tighten the screw too much. In an effort to "fix" this mistake, perhaps they drilled and pinned the wheel. Thus negating ALL fore/aft adjustment of the drive wheel. I have a couple of options here.
1) Leave the pin. - HUGE assumption of accuracy and useability.? 2) Drill and tap 3 more holes and use 3 set screws 120¡ã off setting. I could go so far as to measure and flatten parts of the drive shaft to aid in anti-slip, but I REALLY do not want to modify beyond repair. (First, do no harm.) 3) Broach a keyway in the drive wheel and a LONG keyslot in the shaft. Ideal, but much more entailed than I THINK I need.??
* Your thoughts?
Blade: The blade is a Lennox 3/4" blade
Blade guides: The blade side guides are cammed. After a thorough cleaning, I re-installed them and I intentionally opened the gap as far as possible. I ignorantly assumed they may be causing the derailment. I'll readjust them.?
* Am I correct in assuming the use of feeler gauges may be over kill here?? e.g. guide|blade|feeler gauge|guide Where the feeler guage = total clearance/2
Bow weight: EXCELLENT point on the Bow weight. I noticed the heft of the machine when lowering? the frame. I'll look into adjusting the spring. I never thought about using a luggage scale. I'll have to pick one of those up. As fast as the derail happens, and the amount of cutting that occurs just prior to that, I'd be willing to bet a combination of lack of roller guide support and weight is the culprit here. If that's the case, that is awesome. As it seems I'm quite close! Well, close to the next challenge anyway. :)
More to come, and as always, thank you for your feedback! Darren
?
OK this is a long one:? There are 3
adjustment that determine whether a blade will track on any bandsaw: 1.?? Blade tension 2.?? Driven wheel tilt 3.?? Drive wheel position on its axle ? It helps to
understand why these things matter: Bimetal
bandsaw blades are tensioned to 25-30,000psi stress, flexback carbon steel blades to 15-20,000psi.? That means a ?¡± wide bimetal blade, has about 300lb
tension in it when tensioned properly. With a blade run on both sides of the
wheels, that¡¯s 600lb force pulling the bandwheels together.? The sawframe casting flexes, any slack in
bearings is pulled out, and axles and axle supports bend.? You can¡¯t set the tracking properly until you¡¯ve
got the right tension in the blade.??It
takes more than you think; on a 4x6 its about as much as a normal person can wind
the 2?¡± diameter tension knob one handed, without any aids. It makes a real
twang when plucked, not a dull thok.? Don¡¯t
know what it will take on your 712, but if it¡¯s got a ?¡° blade, the tension
will be half as much again as a ?¡± blade. ?You¡¯ll need to decide where full tension is,
before you start tracking (see comments below on how to mark it) ? The drive
lands on the wheels of metal cutting bandsaws are a (very short) parallel cylinder,
not crowned like a wood bandsaw.? The
blade is supposed to run not quite touching both rims. The rims are just
there to make the blade easier to put on, not to track the blade. The drive and
driven wheels and bearings are manufactured to be parallel to each other when there
is no tilt in the driven wheel. ? However,
when there is tension in the blade, the tension pulls the wheels out of parallel
and the blade runs off. To counter this the driven wheel is tilted in at the
top, which makes the blade track toward the rim on both wheels, more strongly
at the driven wheel than on the drive wheel. ? Broadly
speaking, you adjust the tilt so that the back of the blade runs about 1/32¡±
(1mm) away from the rim of the driven wheel and allow the sawband to find its
own place on the bottom rim, then move the bottom rim on its shaft in or out
until the back edge of the blade just doesn¡¯t touch the rim on the drive wheel
when the blade is at full tension. However
there are a number of things to consider while doing this: 1. ??Tracking
is tension dependent; the greater the tension the more the back edge of the
blade moves away from the rim. 2.?? You can¡¯t change the tilt in the driven
wheel without releasing the tension. 3.?? So, you must be able to re-tension the blade
to the same value each time ¨C make a scratch with a scriber on one half of the
tension mechanism and align the top edge of a piece of sticky tape with the
scratch, stuck to the other half of the mechanism. It'll be different when you change blades as each is a slightly different loop length. 4.?? The roller blade guides do affect tracking a
bit (will make it move in about 1/32¡± at top and 1/8¡± on bottom wheel, but its
easier to track the blade without them in place ¨C so remove until you¡¯ve adjusted
the blade to within 1/16¡± at top and 5/32¡± at bottom 5.?? The tracking is very sensitive to movement
of the tilting set-screw. 1/6th turn changes it a lot near the
correct point, less sensitive when just starting to tilt. 6.?? Start with set screw at ¡®no tilt¡¯ position (release
blade tension, undo both bolts, back setscrew out, then tighten both bolts again,
then turn setscrew back in until it touches). 7.?? It¡¯ll need at least ? turn in on set screw
to start with so re-set the tilt with the set-screw half a turn in. 8.?? Tension blade so that the slack is just out
of the blade, (i.e. no-where near full tension), and turn on/off quickly to
see how the blade moves.? If it sits ok,
then keep it running and slowly increase the blade tension and notice how it
starts to move away from the rims. 9.?? If it still wants to move away from the driven
wheel rim at less than full tension, increase the tilt another ? turn of the
set screw each time, then 1/6th turn when you get near full tension,
until the blade tracks ~1/16¡± from the rim of the driven wheel at full tension.? 10.? ?Don't worry about the drive wheel, unless it still derails even when the driven wheel tracks properly, that shows its way too far in on its shaft (N.B. see comment below about gearbox bearing failure) 11.?? Now move the driven wheel on its shaft
until the back edge of the blade is ~5/32¡± from the rim 12.?? Re-install the roller blade guides and see if
the blade tracks just clear (1/32¡±) of the rims.? Will be ok if it looks like its touching, but
you can¡¯t hear any graunching noises (back edge of blade scraping hard on the
rim). ? That¡¯s about
it, though the blade must be welded squarely (watch for uneven gap from back of
blade to rim as the join passes over the driven wheel) and the gearbox output
shaft bearing must be ok (if it¡¯s failed the output shaft will bend as the
tension is increased, so the blade derails from the bottom wheel only, not the top
one).? You have to keep the blade on
before you can judge either of these, so try to make it track as above first.? ? Don¡¯t be
scared to move the drive wheel out, if it keeps derailing from the bottom when
the top seems OK , though you do need to check that the gearbox output bearing
hasn¡¯t failed? (they do it often enough
and it could be the reason why it was sold). I see your drive wheel is pinned,
4x6¡¯s use a key and a set screw, you could use 243 Loctite until you get the
position right, then re-pin it. ?243 Loctite
is weak enough to be able to change the position of the drive wheel with heat
and a gear puller to set the tracking, but even high strength Loctite won¡¯t be
strong enough to drive when cutting metal.
Let us know how you get on - jv
|
You're right Jerry, the wider the support for the blade the better. Mine were the other way round, outside roller ok near the back of the blade, but inside roller running almost in the middle of the blade.? Fixed by putting a washer between the mount and the bearing/roller per pic.? Got to maintain clearance between the top edge of the roller and the set on the teeth, otherwise would ruin the blade in short order. - jv
|
I shortened the outer guide a little on mine so
it tracks to the top of the blade while the bottom guide is just
above the teeth.
On 10/14/2018 11:52 AM, Terry Coombs
snagone@... [4x6bandsaw] wrote:
?
?
? I see my first reply didn't make it intact ... Just
ordered a 10 pack of the 629 bearings , they match the
measured dimensions of what's on there now . I appreciate the
help John !
? --
? Snag
--
Jerry Durand, Durand Interstellar, Inc.
tel: +1 408 356-3886
@DurandInterstel
|
On 10/14/2018 6:04 AM, Terry Coombs
snagone@... [4x6bandsaw] wrote:
?
?
Not
going reduce your need to go look Terry.??The following metric
size deep groove ball bearings have been used:
|
Inside
Diameter
(mm)
|
Outside
Diameter
(mm)
|
Width
(mm)
|
Bearing
code
|
Comment
|
|
5
|
16
|
5
|
625
|
as
rear guide-roller
|
|
8
|
22
|
7
|
608
|
as
rear guide-roller
|
|
9
|
26
|
8
|
629
|
as
rear guide-roller
|
|
10
|
26
|
8
|
6000
|
as
side guides on later saws
|
|
10
|
30
|
9
|
6200
|
Most popular, esp up to 2000,
esp Taiwanese
|
|
10
|
32
|
10
|
6201
|
only
some older saws, i.e. 80¡¯s Buffalo????
|
- jv
? I see my first reply didn't make it intact ... Just ordered
a 10 pack of the 629 bearings , they match the measured
dimensions of what's on there now . I appreciate the help John !
? --
? Snag
|
Re: OT: Bainbridge 712 resurrection
Nice to know
you¡¯re making progress. Sorry my answers are a little long, but if you don¡¯t have
enough info to understand why things work, you can¡¯t evaluate any how
information meaningfully. To respond to your questions.
?
Tension
So far you¡¯ve
only been interested in blade tracking, but once it tracks you¡¯ll need to make
it cut straight and we get to another can of worms. ?If you read the doc in the files section
called ¡®Bandsaw Chip Characteristics v3.pdf¡¯ you¡¯ll get the gist of what¡¯s
happening as the blade cuts. The bits about ¡®weight on the tooth¡¯ and ¡®blade
tension, stress and buckling¡¯ are important (the concepts, not the numbers
which are different for your blade).
?
Your blade
is a ?¡± deep, 0.035¡± wide beam spanning 10 to 14¡± between the two back support rollers,
(depending on how far apart your guides are), with the work pushing up roughly
in the middle. In engineering terms it¡¯s a very slender beam; the only
thing keeping it straight is its tension.
The most important
thing is that the blade cuts in the direction its pointing. When it buckles
it no longer points straight down and it doesn¡¯t cut square down through the
work. ?You need high enough tension and a
low enough bow weight to stop it buckling, but not so high that the blade
cracks and fails. ?Beyond that the actual
tension doesn¡¯t matter very much.?
?
You say you¡¯re
still in the 'thunk' area, but be careful.? Your blade is longer and thicker than a
4x6 blade, both of which will make the tone lower. The tone it makes depends only
on the span, the weight per unit length of the blade and the tension ¨C if you
pluck the back run of the blade between the guide wheels and use a std blade
then tension is the only?thing that changes the tone.?
?
You¡¯d expect
the bandsaw manufacturers to have given you a tensioning mechanism that you can
use, without resorting to anything special, to tension it properly. ?Since you have to choose a repeatable tension
to set the tracking, wind the tension knob as hard as you can with one hand and
leave it at that. Use the scratch and sticky-tape marker method for this blade
and record the tone on your cellphone¡¯s audio app to make it repeatable for
other blades.
?
I¡¯ve looked
into all the methods of measuring tension I can think of, and there are no
simple, cheap, ones where you know what the actual tension is. ?
?
Wheel crown?
Yes, your
wheels are crowned.? That normally means
the tilt is not so important as the blade will ¡®climb up¡¯ the crown when it
runs.? Since it will climb up no matter
which side of the wheel it¡¯s on, it should settle in the middle. You adjust the
tilt to make the crown on both wheels the same, but the wheels need to
vertically in the same plane, like 2 dishes lying on a flat table.? That makes the drive wheel position that much
more important. If the rims are both the same thickness, you should be able to
get it close with a long straight edge that lies across both wheels, touching at
2 points on both wheels.? A piece of extruded
aluminium 1¡±x ? ¡° unequal length angle section, 1/16th¡± thick,
cut to length to fit inside the saw frame casting is the best I¡¯ve found. Find
it at most hardware stores. Extrusions are normally very straight in short lengths and the
angle section stiffens it. ?
?
Drive wheel
Once you¡¯ve
found the optimum position for the drive wheel it should not need to be moved
again, so pinning it again is not a bad option, since you can do it with the minimum
of tools.? 3 setscrews at 120deg is NOT a
good option, as the whole load is concentrated at 3 points with the maximum
amount of wiggle as it wears.? Wheel
bosses are normally fixed to shafts with 2 set-screws at 90deg, though I¡¯ve
seen an engineering paper where they said you get more friction between shaft
and boss if they¡¯re spaced at 45deg! ?Flats
for the setscrews to bear on are a must, though I¡¯ve no idea whether just 2
set-screws will be enough.? The boss on
that drive wheel looks long enough to put in a double row of setscrews and I¡¯d
be pretty confident that would be enough.?
Broaching/cutting a keyway with a setscrew on top of the key is the
preferred solution, if you can get it done cheaply enough.
?
Blade guides
Yes, feeler gauges
are the right way. The blade is 0.035¡± so a set at 0.036¡± or 0.042¡± will do.
The debate over clearance or no clearance is mainly about whether you cut steel
or aluminium and/or use coolant.? Coolant
and cutting aluminium both cause swarf to stick to the blade and get rolled
through between the blade and the side guide rollers, so clearance is
desirable. Steel swarf and in dry cutting the swarf falls away so only minimal clearance required which gives maximum blade direction control.? The best solution is to use minimum clearance and a blade scraper like in doc 'Liquid Coolant Lube on a 4x6 Bandsaw.pdf' in the Files section.
?
Yeah, I
think bow weight and side roller guide separation are your immediate problem
too.? Happy hunting - jv
|
Re: OT: Bainbridge 712 resurrection
JV, Fantastic feedback. Thank you! Funny how life works. I wouldn't have understood most of your explanation, if I hadn't worked through the challenges first. I greatly appreciate your time and sharing of knowledge. I'll attempt to respond in a semi-orderly fashion.
Blade tension: I believe I'm still in the "thunk" area of tone. I'm right handed and will tension with my left till I get more of a "twang".?
Wheels: These wheels seem to have a bit of crown and no rims (If I understand you). Perhaps a difference in desing? (Pics attached)
Driven Wheel tilt: Thank you for the in depth explanation on how this works. I'll be modifying the saw to include a simple tension gauge/ruler.
Drive wheel: The fact that this wheel is pinned continues to be a point of concern of mine. It looks like this wheel originally used a set screw. I assume the wheel was slipping on the shaft and someone stripped the threads trying to tighten the screw too much. In an effort to "fix" this mistake, perhaps they drilled and pinned the wheel. Thus negating ALL fore/aft adjustment of the drive wheel. I have a couple of options here.
1) Leave the pin. - HUGE assumption of accuracy and useability.? 2) Drill and tap 3 more holes and use 3 set screws 120¡ã off setting. I could go so far as to measure and flatten parts of the drive shaft to aid in anti-slip, but I REALLY do not want to modify beyond repair. (First, do no harm.) 3) Broach a keyway in the drive wheel and a LONG keyslot in the shaft. Ideal, but much more entailed than I THINK I need.??
* Your thoughts?
Blade: The blade is a Lennox 3/4" blade
Blade guides: The blade side guides are cammed. After a thorough cleaning, I re-installed them and I intentionally opened the gap as far as possible. I ignorantly assumed they may be causing the derailment. I'll readjust them.?
* Am I correct in assuming the use of feeler gauges may be over kill here?? e.g. guide|blade|feeler gauge|guide Where the feeler guage = total clearance/2
Bow weight: EXCELLENT point on the Bow weight. I noticed the heft of the machine when lowering? the frame. I'll look into adjusting the spring. I never thought about using a luggage scale. I'll have to pick one of those up. As fast as the derail happens, and the amount of cutting that occurs just prior to that, I'd be willing to bet a combination of lack of roller guide support and weight is the culprit here. If that's the case, that is awesome. As it seems I'm quite close! Well, close to the next challenge anyway. :)
More to come, and as always, thank you for your feedback! Darren
?
OK this is a long one:? There are 3
adjustment that determine whether a blade will track on any bandsaw: 1.?? Blade tension 2.?? Driven wheel tilt 3.?? Drive wheel position on its axle ? It helps to
understand why these things matter: Bimetal
bandsaw blades are tensioned to 25-30,000psi stress, flexback carbon steel blades to 15-20,000psi.? That means a ?¡± wide bimetal blade, has about 300lb
tension in it when tensioned properly. With a blade run on both sides of the
wheels, that¡¯s 600lb force pulling the bandwheels together.? The sawframe casting flexes, any slack in
bearings is pulled out, and axles and axle supports bend.? You can¡¯t set the tracking properly until you¡¯ve
got the right tension in the blade.??It
takes more than you think; on a 4x6 its about as much as a normal person can wind
the 2?¡± diameter tension knob one handed, without any aids. It makes a real
twang when plucked, not a dull thok.? Don¡¯t
know what it will take on your 712, but if it¡¯s got a ?¡° blade, the tension
will be half as much again as a ?¡± blade. ?You¡¯ll need to decide where full tension is,
before you start tracking (see comments below on how to mark it) ? The drive
lands on the wheels of metal cutting bandsaws are a (very short) parallel cylinder,
not crowned like a wood bandsaw.? The
blade is supposed to run not quite touching both rims. The rims are just
there to make the blade easier to put on, not to track the blade. The drive and
driven wheels and bearings are manufactured to be parallel to each other when there
is no tilt in the driven wheel. ? However,
when there is tension in the blade, the tension pulls the wheels out of parallel
and the blade runs off. To counter this the driven wheel is tilted in at the
top, which makes the blade track toward the rim on both wheels, more strongly
at the driven wheel than on the drive wheel. ? Broadly
speaking, you adjust the tilt so that the back of the blade runs about 1/32¡±
(1mm) away from the rim of the driven wheel and allow the sawband to find its
own place on the bottom rim, then move the bottom rim on its shaft in or out
until the back edge of the blade just doesn¡¯t touch the rim on the drive wheel
when the blade is at full tension. However
there are a number of things to consider while doing this: 1. ??Tracking
is tension dependent; the greater the tension the more the back edge of the
blade moves away from the rim. 2.?? You can¡¯t change the tilt in the driven
wheel without releasing the tension. 3.?? So, you must be able to re-tension the blade
to the same value each time ¨C make a scratch with a scriber on one half of the
tension mechanism and align the top edge of a piece of sticky tape with the
scratch, stuck to the other half of the mechanism. It'll be different when you change blades as each is a slightly different loop length. 4.?? The roller blade guides do affect tracking a
bit (will make it move in about 1/32¡± at top and 1/8¡± on bottom wheel, but its
easier to track the blade without them in place ¨C so remove until you¡¯ve adjusted
the blade to within 1/16¡± at top and 5/32¡± at bottom 5.?? The tracking is very sensitive to movement
of the tilting set-screw. 1/6th turn changes it a lot near the
correct point, less sensitive when just starting to tilt. 6.?? Start with set screw at ¡®no tilt¡¯ position (release
blade tension, undo both bolts, back setscrew out, then tighten both bolts again,
then turn setscrew back in until it touches). 7.?? It¡¯ll need at least ? turn in on set screw
to start with so re-set the tilt with the set-screw half a turn in. 8.?? Tension blade so that the slack is just out
of the blade, (i.e. no-where near full tension), and turn on/off quickly to
see how the blade moves.? If it sits ok,
then keep it running and slowly increase the blade tension and notice how it
starts to move away from the rims. 9.?? If it still wants to move away from the driven
wheel rim at less than full tension, increase the tilt another ? turn of the
set screw each time, then 1/6th turn when you get near full tension,
until the blade tracks ~1/16¡± from the rim of the driven wheel at full tension.? 10.? ?Don't worry about the drive wheel, unless it still derails even when the driven wheel tracks properly, that shows its way too far in on its shaft (N.B. see comment below about gearbox bearing failure) 11.?? Now move the driven wheel on its shaft
until the back edge of the blade is ~5/32¡± from the rim 12.?? Re-install the roller blade guides and see if
the blade tracks just clear (1/32¡±) of the rims.? Will be ok if it looks like its touching, but
you can¡¯t hear any graunching noises (back edge of blade scraping hard on the
rim). ? That¡¯s about
it, though the blade must be welded squarely (watch for uneven gap from back of
blade to rim as the join passes over the driven wheel) and the gearbox output
shaft bearing must be ok (if it¡¯s failed the output shaft will bend as the
tension is increased, so the blade derails from the bottom wheel only, not the top
one).? You have to keep the blade on
before you can judge either of these, so try to make it track as above first.? ? Don¡¯t be
scared to move the drive wheel out, if it keeps derailing from the bottom when
the top seems OK , though you do need to check that the gearbox output bearing
hasn¡¯t failed? (they do it often enough
and it could be the reason why it was sold). I see your drive wheel is pinned,
4x6¡¯s use a key and a set screw, you could use 243 Loctite until you get the
position right, then re-pin it. ?243 Loctite
is weak enough to be able to change the position of the drive wheel with heat
and a gear puller to set the tracking, but even high strength Loctite won¡¯t be
strong enough to drive when cutting metal.
Let us know how you get on - jv
|
toggle quoted message
Show quoted text
?
Not going
reduce your need to go look Terry.??The following metric size
deep
groove ball bearings have been used:
|
Inside
Diameter
(mm)
|
Outside
Diameter
(mm)
|
Width
(mm)
|
Bearing code
|
Comment
|
|
5
|
16
|
5
|
625
|
as
rear guide-roller
|
|
8
|
22
|
7
|
608
|
as
rear guide-roller
|
|
9
|
26
|
8
|
629
|
as
rear guide-roller
|
|
10
|
26
|
8
|
6000
|
as
side guides on later saws
|
|
10
|
30
|
9
|
6200
|
Most
popular, esp up to 2000, esp Taiwanese
|
|
10
|
32
|
10
|
6201
|
only
some older saws, i.e. 80¡¯s Buffalo????
|
- jv
|
Re: OT: Bainbridge 712 resurrection
Should have said "Bow weight for 7x12 is 13lb max"? Figure on a normal range of 11-13lb. (It's about 8-10lb for? 4x6) - jv
|
Not going reduce your need to go look Terry.??The following metric size deep
groove ball bearings have been used:
|
Inside Diameter
(mm)
|
Outside
Diameter
(mm)
|
Width
(mm)
|
Bearing code
|
Comment
|
|
5
|
16
|
5
|
625
|
as rear guide-roller
|
|
8
|
22
|
7
|
608
|
as rear guide-roller
|
|
9
|
26
|
8
|
629
|
as rear guide-roller
|
|
10
|
26
|
8
|
6000
|
as side guides on later
saws
|
|
10
|
30
|
9
|
6200
|
Most popular, esp up to 2000, esp
Taiwanese
|
|
10
|
32
|
10
|
6201
|
only some older saws, i.e. 80¡¯s Buffalo????
|
- jv
|
Re: OT: Bainbridge 712 resurrection
Of the top of my head, if it tracks ok but doesn't take downward pressure of cutting, most often the gap between the side roller guide bearings is too large.? Couple of schools of thought on this, one that they should have between zero and 4thou" clearance on the blade, the other that you should run 5-9thou" to allow swarf to run between blade and side roller. Anywhere in the range 0-9 thou" works. Another possibility is that there is too much bow weight (weight of the sawframe casting when just held up above the cut with a weighing device (fishermans spring balance, or better and cheaper now, a $5 digital luggage weigh scale off eBay). Should be about 13lb on a 7x12 when the scale is hooked around the tension knob.? If much more than that can shuck the blade because it will be cutting too fast. - jv?
|
Re: OT: Bainbridge 712 resurrection
OK this is a long one:? There are 3
adjustment that determine whether a blade will track on any bandsaw: 1.?? Blade tension 2.?? Driven wheel tilt 3.?? Drive wheel position on its axle ? It helps to
understand why these things matter: Bimetal
bandsaw blades are tensioned to 25-30,000psi stress, flexback carbon steel blades to 15-20,000psi.? That means a ?¡± wide bimetal blade, has about 300lb
tension in it when tensioned properly. With a blade run on both sides of the
wheels, that¡¯s 600lb force pulling the bandwheels together.? The sawframe casting flexes, any slack in
bearings is pulled out, and axles and axle supports bend.? You can¡¯t set the tracking properly until you¡¯ve
got the right tension in the blade.??It
takes more than you think; on a 4x6 its about as much as a normal person can wind
the 2?¡± diameter tension knob one handed, without any aids. It makes a real
twang when plucked, not a dull thok.? Don¡¯t
know what it will take on your 712, but if it¡¯s got a ?¡° blade, the tension
will be half as much again as a ?¡± blade. ?You¡¯ll need to decide where full tension is,
before you start tracking (see comments below on how to mark it) ? The drive
lands on the wheels of metal cutting bandsaws are a (very short) parallel cylinder,
not crowned like a wood bandsaw.? The
blade is supposed to run not quite touching both rims. The rims are just
there to make the blade easier to put on, not to track the blade. The drive and
driven wheels and bearings are manufactured to be parallel to each other when there
is no tilt in the driven wheel. ? However,
when there is tension in the blade, the tension pulls the wheels out of parallel
and the blade runs off. To counter this the driven wheel is tilted in at the
top, which makes the blade track toward the rim on both wheels, more strongly
at the driven wheel than on the drive wheel. ? Broadly
speaking, you adjust the tilt so that the back of the blade runs about 1/32¡±
(1mm) away from the rim of the driven wheel and allow the sawband to find its
own place on the bottom rim, then move the bottom rim on its shaft in or out
until the back edge of the blade just doesn¡¯t touch the rim on the drive wheel
when the blade is at full tension. However
there are a number of things to consider while doing this: 1. ??Tracking
is tension dependent; the greater the tension the more the back edge of the
blade moves away from the rim. 2.?? You can¡¯t change the tilt in the driven
wheel without releasing the tension. 3.?? So, you must be able to re-tension the blade
to the same value each time ¨C make a scratch with a scriber on one half of the
tension mechanism and align the top edge of a piece of sticky tape with the
scratch, stuck to the other half of the mechanism. It'll be different when you change blades as each is a slightly different loop length. 4.?? The roller blade guides do affect tracking a
bit (will make it move in about 1/32¡± at top and 1/8¡± on bottom wheel, but its
easier to track the blade without them in place ¨C so remove until you¡¯ve adjusted
the blade to within 1/16¡± at top and 5/32¡± at bottom 5.?? The tracking is very sensitive to movement
of the tilting set-screw. 1/6th turn changes it a lot near the
correct point, less sensitive when just starting to tilt. 6.?? Start with set screw at ¡®no tilt¡¯ position (release
blade tension, undo both bolts, back setscrew out, then tighten both bolts again,
then turn setscrew back in until it touches). 7.?? It¡¯ll need at least ? turn in on set screw
to start with so re-set the tilt with the set-screw half a turn in. 8.?? Tension blade so that the slack is just out
of the blade, (i.e. no-where near full tension), and turn on/off quickly to
see how the blade moves.? If it sits ok,
then keep it running and slowly increase the blade tension and notice how it
starts to move away from the rims. 9.?? If it still wants to move away from the driven
wheel rim at less than full tension, increase the tilt another ? turn of the
set screw each time, then 1/6th turn when you get near full tension,
until the blade tracks ~1/16¡± from the rim of the driven wheel at full tension.? 10.? ?Don't worry about the drive wheel, unless it still derails even when the driven wheel tracks properly, that shows its way too far in on its shaft (N.B. see comment below about gearbox bearing failure) 11.?? Now move the driven wheel on its shaft
until the back edge of the blade is ~5/32¡± from the rim 12.?? Re-install the roller blade guides and see if
the blade tracks just clear (1/32¡±) of the rims.? Will be ok if it looks like its touching, but
you can¡¯t hear any graunching noises (back edge of blade scraping hard on the
rim). ? That¡¯s about
it, though the blade must be welded squarely (watch for uneven gap from back of
blade to rim as the join passes over the driven wheel) and the gearbox output
shaft bearing must be ok (if it¡¯s failed the output shaft will bend as the
tension is increased, so the blade derails from the bottom wheel only, not the top
one).? You have to keep the blade on
before you can judge either of these, so try to make it track as above first.? ? Don¡¯t be
scared to move the drive wheel out, if it keeps derailing from the bottom when
the top seems OK , though you do need to check that the gearbox output bearing
hasn¡¯t failed? (they do it often enough
and it could be the reason why it was sold). I see your drive wheel is pinned,
4x6¡¯s use a key and a set screw, you could use 243 Loctite until you get the
position right, then re-pin it. ?243 Loctite
is weak enough to be able to change the position of the drive wheel with heat
and a gear puller to set the tracking, but even high strength Loctite won¡¯t be
strong enough to drive when cutting metal.
Let us know how you get on - jv
|
Re: OT: Bainbridge 712 resurrection
Welll, made some progress. I've been able to clean most of the moving bits and adjust the saw to the point where the blade runs with out coming off vertically and horizontally. However, as soon as I introduced a small bit of right angle steel, the blade falls off. The good thing is, the blade cut like hot knife like in butter! Less than 2 seconds and about 1/3" was cut. Bad thing about this? Now I REALLY want this working. :)? Perhaps tighten the blade? Not sure how far to push the tightening. The blade does make a note when tightened. Not sure what note, but it? twangs. Any ideas? Thanks, Darren
ps. If these types of updates are unwelcome, just let me know.?
|
Jerry Durand