Re: Blade tracking problem
??? ??? I would pull the blade & check each wheel for
deflection both in & out & side to side . Have you ever
checked the oil level in your gear box ? I checked mine he day I
brought it home used . I could see that it was one of the newer
saws with very little wear visible till I got the blade cover off
& the gear box cover off . I bought mine with a bad motor ,
but I got it real cheap . I could see where the blade had been
scraping the inside cover at both the top & bottom . That was
the easy fix , I think I replaced one bearing & adjusted . But
before I could adjust the wheels I had to address the gearbox
issue . Mine was bone dry . There were 3 seals on one of the
shafts all of which were installed wrong , I replaced 2 seals
& maybe a bearing . Fortunately I caught mine before it had
caused a lot of damage to the brass gear inside the gear box . The
dry gear box on these saws is more common then you would think .
Make sure your wheels are both turning true & flat . I see
that the parts list for these saws?? ( the ones they currently
sell ) shows 2 seals but I could only find one in the parts list .
I was able to get the #'s off the bad ones & went to my
bearing house & got some good quality seals . I think there's
only 2 different bearings in these saws , I went on Amazon &
got a ten pack of each for @ $20 .
animal
On 2/15/2022 9:00 AM, Mark Kimball
wrote:
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The other day I was cutting some stock with my HF bandsaw when I
noticed a new scraping sound coming from the area of the bottom
(drive) wheel.? Further examination showed that the blade was
riding far enough out that it was scraping the inside of the blade
cover.? Thinking that I just needed to adjust the tracking
(something I haven't done since buying the saw), I started in on
that -- but quickly discovered that the blade was riding properly
on the upper wheel.? Not quite touching the flange.
Some additional experimentation showed that the drive wheel
tracking problem is eased when I reduce the blade tension a bit.?
I don't think I'm overtightening the blade and bending the frame
-- I'd think the upper wheel would be more affected (but I could
be wrong about that).
I'm not hearing any noise from the drive shaft bearings so think
it's unlikely they have worn enough to cause these symptoms.?
Maybe I just noticed something that is common to these lightweight
machines?? On the other hand, if the problem is flexing in the
drive shaft, that could be a recipe for metal fatigue and eventual
failure.
Comments?? Has anyone else observed this?
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The other day I was cutting some stock with my HF bandsaw when I noticed a new scraping sound coming from the area of the bottom (drive) wheel.? Further examination showed that the blade was riding far enough out that it was scraping the inside of the blade cover.? Thinking that I just needed to adjust the tracking (something I haven't done since buying the saw), I started in on that -- but quickly discovered that the blade was riding properly on the upper wheel.? Not quite touching the flange.
Some additional experimentation showed that the drive wheel tracking problem is eased when I reduce the blade tension a bit.? I don't think I'm overtightening the blade and bending the frame -- I'd think the upper wheel would be more affected (but I could be wrong about that).
I'm not hearing any noise from the drive shaft bearings so think it's unlikely they have worn enough to cause these symptoms.? Maybe I just noticed something that is common to these lightweight machines?? On the other hand, if the problem is flexing in the drive shaft, that could be a recipe for metal fatigue and eventual failure.
Comments?? Has anyone else observed this?
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On Mon, Feb 14, 2022 at 04:19 PM, Rick Sparber wrote:
These straps deflect enough to not hold well:?
I see your point now although I seldom have a problem holding small stock. I have the 3/8 plate on the stationary jaw and just move the other jaw toward the blade. Most the force is on the fixed jaw.?
I apologize, I was lazy and didn't completely read your pdf. As a result most my comments were not appropriate. I think the 1-inch is overkill but I also thought you were attaching the stock to the jaws. My bad!
Mark
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These straps deflect enough to not hold well:?
Rick
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On Mon, Feb 14, 2022 at 06:44 AM, Rick Sparber wrote:
You make an important point about the blade rubbing. I'll update the article.
I don't understand you comment about 1/4" thick jaws working since they bent when I used them. In fact, I thiink they were more like 3/8" thick. What you you mean by "clamping range"?.
I may be confused. I was talking about the attachment you posted. The additional jaws attached to your original jaws looked to be about 1/2" thick but then I read the attachment again and it said 1-inch!!!? If this is the case you lose 2-inch of clamping range. The 1"-inch on the moving jaw limits you further because the moving jaw hits the blade guide. How of earth do you bend 1/4 plate? If we are on the same page and have the same saw (which in both cases we may not) something else would likely break before the 1/4" plate would bend. In fact my original fixed jaw is likely less than 1/4" thick in some places. I used 3/8" just because I had it but I have taken if off a several times to have the full capacity of the vise.?
?
I attached two pics. the first shows where the blade guide hits the movable jaw and the second is how I hold small stock. And I totally agree about the gap where the blade goes into the table. I need to fix mine.?
Mark
?
 
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Hi Rick,
A simple & clever way to cut small parts on the band saw! As
usual, nice detail!
Not sure about all the criticism that came in. It's not like your
small-part jaws go on there, and more importantly, stay there
after installation. Put it on, cut some small parts, and remove
it. I have a few fixtures for doing 'specialty' tasks, including
for cutting small parts.
I bought a small vise, for cutting small parts. Pic attached.
Pretty straight forward. (The v-groove in the vise is handy for
small rounds, as pictured)
I built a fixture for making angled cuts with tubing. My Grizz
saw cuts angles, but some angles it won't do.
I have another simple fixture, which is just a drilled &
tapped plate, for holding odd shaped items using step clamps. I've
made some shorter jaws, longer jaws, and all sorts of goodies, for
tasks where the stock jaws just won't do it. Again, they are not
made to be on the saw all the time.
Nice job Rick!
Other Bill
On 2/12/2022 4:04 PM, Rick Sparber via
groups.io wrote:
The jaws on my
bandsaw do not extend to the blade. There is also a cutout below
the blade to enable the shavings to fall away. This makes it
hard to clamp small bits of metal for sawing. These drop-in jaws
solve the problem.
?
?
If you are
interested, please, click .
?
?Your comments
are welcome. All of us are smarter than any one of us.
?
?
?Thanks,
?
?
?
Rick
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Yup. This trade off works for me.?
Rick
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By using 1" bars you have taken out 2" that will fit between the jaws. Paul M
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Mark,
You make an important point about the blade rubbing. I'll update the article.
I don't understand you comment about 1/4" thick jaws working since they bent when I used them. In fact, I thiink they were more like 3/8" thick. What you you mean by "clamping range"?.
The "larger plate" is the one on the left end of the fixed jaw. Is that the one you are referring to??
I will update the article to say that these jaws are only intended for 90 degree cuts.?
Thanks for your comments.
Rick
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Hi Rick,
thanks for the posting. ? The postings have been pretty slow lately.
I did a similar jaw modification. ? I took a number of pictures ?and provided a short description in the photo section.
I think I will try a hard wood block in the open gap where the blade settles. ? That way, the saw will cut its own slot and the wood will support the part. ?
I think the best solution is to make a separate clamp that can be clamped into the saw vise. ? That way one can carefully set up the part on the bench before transferring it to the saw. ? I have to pencil this out and get some steel.
thanks for posting.
?
Dave
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On Sat, Feb 12, 2022 at 06:04 PM, Rick Sparber wrote:
The jaws on my bandsaw do not extend to the blade. There is also a cutout below the blade to enable the shavings to fall away. This makes it hard to clamp small bits of metal for sawing. These drop-in jaws solve the problem.
Thanks for sharing although I have a few observations and concerns. First, 1/4" steel would have been totally adequate on the jaws and you have limited your clamping range. Second, the moving jaw will hit the blade guide when the vise is opened very far. Third, the narrow gap under the stock is a plus! Forth, put the larger plate on the back jaw only for the reason listed above. Fifth, when you cut a 45 degree angle the additional plate will be in the blade path (you can remove it when needed). Sixth, *leave a slight gap between the blade and the back jaw (it looks like you did).
*I added a back jaw and trimmed a bit off with the saw. It seemed like a logical approach but it was a bad idea. The steel continues to rub on the side of the blade and will dull the teeth on one side. After maybe 20 cuts the blade will start to wander in the cut.??
?
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The jaws on my bandsaw do not extend to the blade. There is also a cutout below the blade to enable the shavings to fall away. This makes it hard to clamp small bits of metal for sawing. These drop-in jaws solve the problem.
?
?
If you are interested, please, click .
?
?Your comments are welcome. All of us are smarter than any one of us.
?
?
?Thanks,
?
?
?
Rick
|
Re: Band saw blade tension
Great stuff John, i too appreciate all your commenting over the years. I've always considered you as one of "the ones you can trust" when you make a comment -- Kelly aka kjb25
HF 4x6
Utah, USA
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Re: Band saw blade tension
Hi all
Been thinking and there is a simpler way to tension a 4x6's blade that everyone can do at no cost, all it needs is a cellphone.
I've made 30sec audio files of a properly tensioned10-14TPI?blade being plucked every 2-3sec.? The 1st file is the blade tensioned?to 22500psi stress for bimetal, the other to 17500psi? stress for carbon steel blades.
Load the files?on your cell phone.
Tension up the blade until the sounds match when you pluck the?back run of the blade. I used the flesh of my thumb or finger, not the nail, as the nail makes a sound that is harder to match.
It's?better than using an App or formula to?work out a frequency and matching to a pure MIDI tone - this is the actual sound of a?blade, at known tension, set with a calibrated loadcell.
Its a bit hard on your fingers so a couple of painless alternatives, that can be used to re-tension the blade, are given.??
This method also provides a way for anyone to calibrate the cheap Chinese ZTTO TC-1 spoke tension meter,?without needing to compare it to a Park Tool.?
I've written out the methods and posted them to the Files section too, along with the audio files. The 3 files are in a single folder called 'Blade tensioning methods' so that they'll be together- jv
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Re: Band saw blade tension
Hi George,
I totally agree, I was going to thank John but you beat me to it!
It is so refreshing to read a post from someone (John) who speaks with facts and not just opinions.
Cheers Paul
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On 01 November 2021 at 18:06 "George Taylor, IV" <gtaylor@...> wrote:
John,
?
Thank you very much ¨C your knowledge is greatly appreciated and valuable to the community.
?
George
?
?
S-type load cells?work in both tension and compression and these ones have a 7/16 UNC threaded hole in top and bottom, which I made pivot pin type connections to.
The blade is just silver soldered to the connectors.
Because I bought the loadcell and the reader as a pair, the loadcell just plugged into the reader.
Totally Chinese instructions that I could not decipher and?no amount of pressing and holding buttons?etc could I make it read in Lb's or Kgs though its supposed to.?
The reader?reads in units of 20g, Reading of 10,000 units = 200kg. A minor pain in the butt but otherwise its been faultless.??
When I calibrated it against the research grade 500kg loadcell on the tensile tester at the engineering school, the thing calibrated perfectly with slope of 1:1 and intercept of zero, so no need to worry about the accuracy of these $20 loadcells.? Even the $5 Airport luggage weigh scales were as accurate.
All loadcells?creep a little if left under load, I found?out too, but if you read it within a minute or two it's stable.
Easiest to get off AliExpress see the attached Word doc with some screenshots of searches - jv
?
?
?
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Re: Band saw blade tension
John, ? Thank you very much ¨C your knowledge is greatly appreciated and valuable to the community. ? George ?
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From: [email protected] On Behalf Of John Vreede Sent: Saturday, October 30, 2021 6:56 PM To: [email protected] Group Moderators < [email protected]> Subject: Re: [4x6bandsaw] Band saw blade tension ? S-type load cells?work in both tension and compression and these ones have a 7/16 UNC threaded hole in top and bottom, which I made pivot pin type connections to. The blade is just silver soldered to the connectors. Because I bought the loadcell and the reader as a pair, the loadcell just plugged into the reader. Totally Chinese instructions that I could not decipher and?no amount of pressing and holding buttons?etc could I make it read in Lb's or Kgs though its supposed to.? The reader?reads in units of 20g, Reading of 10,000 units = 200kg. A minor pain in the butt but otherwise its been faultless.?? When I calibrated it against the research grade 500kg loadcell on the tensile tester at the engineering school, the thing calibrated perfectly with slope of 1:1 and intercept of zero, so no need to worry about the accuracy of these $20 loadcells.? Even the $5 Airport luggage weigh scales were as accurate. All loadcells?creep a little if left under load, I found?out too, but if you read it within a minute or two it's stable. Easiest to get off AliExpress see the attached Word doc with some screenshots of searches - jv ?
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Re: Band saw blade tension
Hi George I found the calibration data for the 200kg loadcell Not actually zero intercept?but 3 in 8000 is near enough see graph attached
On Sun, Oct 31, 2021 at 9:22 AM George Taylor, IV < gtaylor@...> wrote: John,
How is your load cell set up to measure tension.? where can i get a load cell appropriate for this?
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Re: Band saw blade tension
Hi George S-type load cells?work in both tension and compression and these ones have a 7/16 UNC threaded hole in top and bottom, which I made pivot pin type connections to. The blade is just silver soldered to the connectors. Because I bought the loadcell and the reader as a pair, the loadcell just plugged into the reader. Totally Chinese instructions that I could not decipher and?no amount of pressing and holding buttons?etc could I make it read in Lb's or Kgs though its supposed to.? The reader?reads in units of 20g, Reading of 10,000 units = 200kg. A minor pain in the butt but otherwise its been faultless.?? When I calibrated it against the research grade 500kg loadcell on the tensile tester at the engineering school, the thing calibrated perfectly with slope of 1:1 and intercept of zero, so no need to worry about the accuracy of these $20 loadcells.? Even the $5 Airport luggage weigh scales were as accurate. All loadcells?creep a little if left under load, I found?out too, but if you read it within a minute or two it's stable. Easiest to get off AliExpress see the attached Word doc with some screenshots of searches - jv
On Sun, Oct 31, 2021 at 9:22 AM George Taylor, IV < gtaylor@...> wrote: John,
How is your load cell set up to measure tension.? where can i get a load cell appropriate for this?
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Re: Band saw blade tension
John,
How is your load cell set up to measure tension.? where can i get a load cell appropriate for this?
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Re: Band saw blade tension
Ed -? I tested your method and it's perhaps a little high (depending on if the threads are greased or not) My go-to method for many years was very similar:- Tighten it as hard as a normal person can (not a gorilla?or a wimp) without?any aids (like a rag). but I never knew whether that was correct or?not. I have the gear now, so set up the blade with the load cell and standard tensioning rod&knob?per the picture and tested it. - With degreased?threads (as it comes from?the factory) with one hand and no rag or other aid, I could only get it to 230lb tension which?is ~21000 psi?stress.? This is just over the limit for a?carbon steel blade and only marginally tight enough for a bimetal blade
- Degreased, one hand?+ rag could get it to 270 lb tension which is ~25000 psi the upper limit of what you should run a bimetal blade.
- With grease?on the threads and knob/washer/casting and one hand/no rag I could get it to 250lb tension, ~23000 psi just over the midpoint of the bimetal blade?
- With grease, one hand?+ rag could get to 300lb tension ~28000 psi, well over the limit for bimetal on the small wheels of a 4x6.
- With grease?+ rag and two hands I could get it to 330lb >30000psi
From these tests, if?you're normal strength like me, greasing the threads and doing it up as tight as you can?with one hand only, the tension will be right on the money.?My problem is that it takes time to get it that tight and it hurts my hand, so I prefer to use other?methods. But if you only tension the?blade once in a blue moon, then it's a pretty good method.
James -? It actually?needs to be tighter than '...just not slipping ...' , unless you have the bow weight wound back to where there's?not much weight on the teeth in the cut (i.e. bow weight <5lb). If this works for you, the bow weight will be significantly less than you could apply (8lb max on a 4x6 ) with good tension, so the saw will cut slower than it safely could. Low blade tension and bow weight >5lb sends the blade into a degree of 'elastic lateral torsional?buckling', where the top edge of the blade tips sideways. Then the blade?cuts off angle.The more bow weight, the more it tips. It's elastic so the blade just straightens up without damage?afterwards, often pinging away from the cut face at the end - jv
On Sat, Oct 30, 2021 at 9:45 AM n5kzw < n5kzw@...> wrote: The method I use was posted on rec.crafts.metalworking.? First tou tighten the blade as much as you can with your hand, then you throw a shop rag on the tensioning knob and see how much tighter you can get it.? This method has served me well on my HF unit for many years. - Ed
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Mark
John Vreede
