Hi? Mark The human eye is pretty damn good at seeing squareness and parallelicity so I don't doubt that groove in the bracket seat is not parallel to the arm it slides on. I've seen it on ones I've dealt with too.? Unfortunately the parts are not made with much precision. I believe the manufacturers build in so much slop (they call it 'adjustability') that you can mostly get it adjusted correctly, but I've had to file the corners of a bracket tongue to get enough twist to align a blade vertical on a brand new machine. For the purposes of your drawing the assumption that they should be parallel is correct - jv
Hi John,
The 40 degree angle is closer to what I measured when I looked at the angle between the blade guide support's square dovetail and its body.? That's part #84 in my Harbor Freight owner's manual.? It's called the "lower blade guide bracket seat" in my manual.? But I wasn't sure if the plane of the bracket seat's body is anywhere close to vertical (when the body frame part #62 is horizontal).? Apparently it is.
I also saw that when the blade is twisted to be vertical the plane of its wide dimension passes through the M8 hole in the bracket seat.? That makes a lot of sense!? However, it doesn't seem to be exactly parallel to the long axis of the dovetail.? ?Maybe that's to account for the necessary clearance between the saw blade and guide bearings?? With zero clearance the blade and guide bearing axes would be parallel, but adding clearance would result in needing some additional "twist offset" on the part of the blade guide.? More clearance = more angular offset.? But how large is that angle?
Knowing that the bearings are 9mm long, for .005" clearance I calculate less than 1 degree. .010" would come to 1.6 degrees.? Not much to worry about I'd say.? So the dovetail alignment issue may be an observation error on my part (I just eyeballed it), or perhaps a minor design error.
Mark
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Hi John,
The 40 degree angle is closer to what I measured when I looked at the angle between the blade guide support's square dovetail and its body.? That's part #84 in my Harbor Freight owner's manual.? It's called the "lower blade guide bracket seat" in my manual.? But I wasn't sure if the plane of the bracket seat's body is anywhere close to vertical (when the body frame part #62 is horizontal).? Apparently it is.
I also saw that when the blade is twisted to be vertical the plane of its wide dimension passes through the M8 hole in the bracket seat.? That makes a lot of sense!? However, it doesn't seem to be exactly parallel to the long axis of the dovetail.? ?Maybe that's to account for the necessary clearance between the saw blade and guide bearings?? With zero clearance the blade and guide bearing axes would be parallel, but adding clearance would result in needing some additional "twist offset" on the part of the blade guide.? More clearance = more angular offset.? But how large is that angle?
Knowing that the bearings are 9mm long, for .005" clearance I calculate less than 1 degree. .010" would come to 1.6 degrees.? Not much to worry about I'd say.? So the dovetail alignment issue may be an observation error on my part (I just eyeballed it), or perhaps a minor design error.
Mark
|
Hi Mark The angle is different for 4x6's and 5x6's. 40 deg for 4x6's? 45 deg for 5x6's, that's how they get the extra depth of cut, but pay for it with reduced throat width - jv
Most saws are set at a 45 degree twist from the bed (mine measures 45.3 degrees) and you would need to set the blade twist 90 degrees to the bed. I would think only a 2 or 3 degree adjustment each way would be enough. This would allow a range from 42 to 48 degrees to dial in the blade adjustment as needed. ?Has anyone here determined the blade twist angle necessary to get a vertical cut?? I'm trying to create a model of the blade guide assembly.?
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Most saws are set at a 45 degree twist from the bed (mine measures 45.3 degrees) and you would need to set the blade twist 90 degrees to the bed. I would think only a 2 or 3 degree adjustment each way would be enough. This would allow a range from 42 to 48 degrees to dial in the blade adjustment as needed.
toggle quoted message
Show quoted text
On Sep 15, 2023, at 12:17 PM, Mark Kimball <markkimball51@...> wrote:
?Has anyone here determined the blade twist angle necessary to get a vertical cut?? I'm trying to create a model of the blade guide assembly.?
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Has anyone here determined the blade twist angle necessary to get a vertical cut?? I'm trying to create a model of the blade guide assembly.?
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Re: A mistake and recovery
I added a motor heater to my saw. ? I have pictures in the photo section. ?It cost more than a dollar, but was less than $25. ? I feel that I can leave my saw unattended, if necessary.
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Re: A mistake and recovery
YES!? I've always been a "just do it" type, but now I actually think about those sorts of things.? This week I need to buy 56 8' 1x4", and lately, I've been buying 3/4" plywood and cutting it down to save $, but this time I'm going to buy the sticks instead.? The customer will just have to eat the difference. It's a LOT easier to deal with the sticks instead of thick 4x8s!
-Dave
On Sunday, September 3, 2023 at 05:46:04 PM PDT, mike allen <animal@...> wrote:
??? ??? I bet its a hell of a lot better for yer back too !! I
have my saw mounted on a old stand from a Craftsman router , its
at a pretty darn comfortable height for me . Part of the work
smarter not harder plan .
animal
On 9/3/23 4:32 PM, Dave Seiter wrote:
My saw is on Harbor Freights'
second cheapest rolling metal cart (three shelves); the top
shelf is inverted, and the saw sits on two sections of 2"
square tubing.?? Works great!
-Dave
On Saturday, September 2, 2023 at 07:01:20 PM PDT,
davesmith1800 <davesmith1@...> wrote:
I have mine on wheels so
move around the shop .
This keep a eye on saw as drilling or turning in
sometime as welding too.
|
Re: A mistake and recovery
??? ??? I bet its a hell of a lot better for yer back too !! I
have my saw mounted on a old stand from a Craftsman router , its
at a pretty darn comfortable height for me . Part of the work
smarter not harder plan .
animal
On 9/3/23 4:32 PM, Dave Seiter wrote:
toggle quoted message
Show quoted text
My saw is on Harbor Freights'
second cheapest rolling metal cart (three shelves); the top
shelf is inverted, and the saw sits on two sections of 2"
square tubing.?? Works great!
-Dave
On Saturday, September 2, 2023 at 07:01:20 PM PDT,
davesmith1800 <davesmith1@...> wrote:
I have mine on wheels so
move around the shop .
This keep a eye on saw as drilling or turning in
sometime as welding too.
|
Re: A mistake and recovery
In my shop, almost everything is on wheels due to minimal space.
My saw is on Harbor Freights' second cheapest rolling metal cart (three shelves); the top shelf is inverted, and the saw sits on two sections of 2" square tubing.? I also moved the casters as close to the sides as possible to make it more stable.? Works great!
-Dave
On Saturday, September 2, 2023 at 07:01:20 PM PDT, davesmith1800 <davesmith1@...> wrote:
I have mine on wheels so move around the shop . This keep a eye on saw as drilling or turning in sometime as welding too.
|
Re: A mistake and recovery
On Frank Hoose's original mini-lathe.com site he related his experience with the exact same situation.? He left the saw running when he went into the house and got distracted by something on TV.
Kurt Laughlin.
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Re: A mistake and recovery
When had shop I had larger bandsaws I had a drill press and a grinder. I used the? 4x6 to move to larger tools.?
I never let saw run by it self.?
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Re: A mistake and recovery
Thank you. That’s what I do, too!
On Saturday, September 2, 2023, 3:04 PM, rfmarchi1 <rfmarchi@...> wrote:
You got lucky. The inexpensive motors on many of these saws don’t usually have thermal motor protections so you need to be particularly careful. I don’t use sacrificial stock. I just make sure that the shutoff switch is adjusted properly
to shut the saw off at the end of the cut. I am careful to manually hold the blade up off the workpiece until it is up to speed to make sure that it doesn’t get snagged on something and stalls before starting to cut. This is a particularly good idea when cutting
rebar or other rough finished stock. And, I don’t let the saw run unattended; keeping within hearing distance is a good practice in case something goes wrong.
?
I’m glad it worked out for yoou.
?
Sent from for Windows
?
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Re: A mistake and recovery
toggle quoted message
Show quoted text
On Sunday, September 3, 2023, 8:14 AM, Bill Armstrong <bill_1955@...> wrote:
Some MSHA & OSHA rules make sense, like the
one about not leaving running machinery or equipment unattended, a
rule like many, born out of disaster.
You are lucky indeed! I can tell you stories of unattended
machines left running, where the outcomes were very expensive, and
some could have proved fatal.
Other Bill
On 9/1/2023 10:20 AM, Mark Kimball
wrote:
A few days ago I was cutting a small length of 1" square stock
with my bandsaw.? I supported the piece on a sacrificial strip of
aluminum to make sure it wouldn't tip down while being sawn.? The
sacrificial piece was a bit narrower than the stock so I could
grip it with the vise.? The mistake I made was to turn the saw on
and then I left for a "quick" errand.? But that turned into a much
longer interval -- so the saw was unattended.? Well, when I
finally came back the saw had stopped, but that's because the
cutoff piece had jammed the saw.? Probably because the sacrificial
piece prevented the saw from immediately turning off.? The scrap
got sucked into the bearing guides and jammed.
I didn't smell a burnt odor coming from the motor and the breaker
for that outlet had tripped so I was hopeful that the saw was OK,
but that turned out to not be the case.? With power restored and
the jam cleared, the motor clearly was dead.? My ohmmeter showed
an open connection.? It wasn't the switch which only left the
motor as the location of the open circuit.
I found that Harbor Freight claims to have replacement bandsaw
motors but they're about $150 so I thought it was worth my time to
see if I could fix the motor.? I found an online forum where
someone had repaired theirs by replacing a thermal cutout located
inside the motor housing so......maybe I might get lucky.
I removed the motor and took off the end nearest the power cord
connection but unfortunately my model had no thermal cutout.?
Still no bad burnt odor and the windings looked OK so I used my
ohmmeter some more to see if I could locate the open connection.?
I had to remove the heat-shrink tubing from the power
cord-to-windings connections and noticed that the hot and ground
return wires were stuck together.? More examination revealed that
they were melted.? ?They had been tied very tightly by some kind
of string so when the motor got hot enough to soften the
insulation the wires came in contact, blew out and tripped the
breaker.
Long story short, I replaced the power cord connections,
re-assembled the motor and tested it.? It ran with no noises,
tripped breakers or any obvious complaint.
I got lucky and learned a lesson.? Don't walk away from a running
bandsaw.
|
Re: A mistake and recovery
Some MSHA & OSHA rules make sense, like the
one about not leaving running machinery or equipment unattended, a
rule like many, born out of disaster.
You are lucky indeed! I can tell you stories of unattended
machines left running, where the outcomes were very expensive, and
some could have proved fatal.
Other Bill
On 9/1/2023 10:20 AM, Mark Kimball
wrote:
A few days ago I was cutting a small length of 1" square stock
with my bandsaw.? I supported the piece on a sacrificial strip of
aluminum to make sure it wouldn't tip down while being sawn.? The
sacrificial piece was a bit narrower than the stock so I could
grip it with the vise.? The mistake I made was to turn the saw on
and then I left for a "quick" errand.? But that turned into a much
longer interval -- so the saw was unattended.? Well, when I
finally came back the saw had stopped, but that's because the
cutoff piece had jammed the saw.? Probably because the sacrificial
piece prevented the saw from immediately turning off.? The scrap
got sucked into the bearing guides and jammed.
I didn't smell a burnt odor coming from the motor and the breaker
for that outlet had tripped so I was hopeful that the saw was OK,
but that turned out to not be the case.? With power restored and
the jam cleared, the motor clearly was dead.? My ohmmeter showed
an open connection.? It wasn't the switch which only left the
motor as the location of the open circuit.
I found that Harbor Freight claims to have replacement bandsaw
motors but they're about $150 so I thought it was worth my time to
see if I could fix the motor.? I found an online forum where
someone had repaired theirs by replacing a thermal cutout located
inside the motor housing so......maybe I might get lucky.
I removed the motor and took off the end nearest the power cord
connection but unfortunately my model had no thermal cutout.?
Still no bad burnt odor and the windings looked OK so I used my
ohmmeter some more to see if I could locate the open connection.?
I had to remove the heat-shrink tubing from the power
cord-to-windings connections and noticed that the hot and ground
return wires were stuck together.? More examination revealed that
they were melted.? ?They had been tied very tightly by some kind
of string so when the motor got hot enough to soften the
insulation the wires came in contact, blew out and tripped the
breaker.
Long story short, I replaced the power cord connections,
re-assembled the motor and tested it.? It ran with no noises,
tripped breakers or any obvious complaint.
I got lucky and learned a lesson.? Don't walk away from a running
bandsaw.
|
Re: A mistake and recovery
I have mine on wheels so move around the shop . This keep a eye on saw as drilling or turning in sometime as welding too.
|
Re: A mistake and recovery
Mark,
I suggest you file a patent on a using an insulating material
that will melt and short shortly before a motor is damaged from
overheating.? By utilizing the circuit's over current protection,
this invention can provide reliable motor overheating protection
for about a cent's worth of insulation.
Once your patent is granted, you can file infringement claims on
all motor manufacturers with shoddy construction, thereby forcing
them to improve their build quality.? That will make you a hero!
(sarcasm aside, congrats on finding an easy fix!)
On 9/2/2023 3:10 AM, Hettie Chom wrote:
toggle quoted message
Show quoted text
Hi, a very good selution for your problem with a
satifying end.
A
few days ago I was cutting a small length of 1" square stock
with my bandsaw.? I supported the piece on a sacrificial strip
of aluminum to make sure it wouldn't tip down while being
sawn.? The sacrificial piece was a bit narrower than the stock
so I could grip it with the vise.? The mistake I made was to
turn the saw on and then I left for a "quick" errand.? But
that turned into a much longer interval -- so the saw was
unattended.? Well, when I finally came back the saw had
stopped, but that's because the cutoff piece had jammed the
saw.? Probably because the sacrificial piece prevented the saw
from immediately turning off.? The scrap got sucked into the
bearing guides and jammed.
I didn't smell a burnt odor coming from the motor and the
breaker for that outlet had tripped so I was hopeful that the
saw was OK, but that turned out to not be the case.? With
power restored and the jam cleared, the motor clearly was
dead.? My ohmmeter showed an open connection.? It wasn't the
switch which only left the motor as the location of the open
circuit.
I found that Harbor Freight claims to have replacement bandsaw
motors but they're about $150 so I thought it was worth my
time to see if I could fix the motor.? I found an online forum
where someone had repaired theirs by replacing a thermal
cutout located inside the motor housing so......maybe I might
get lucky.
I removed the motor and took off the end nearest the power
cord connection but unfortunately my model had no thermal
cutout.? Still no bad burnt odor and the windings looked OK so
I used my ohmmeter some more to see if I could locate the open
connection.? I had to remove the heat-shrink tubing from the
power cord-to-windings connections and noticed that the hot
and ground return wires were stuck together.? More examination
revealed that they were melted.? ?They had been tied very
tightly by some kind of string so when the motor got hot
enough to soften the insulation the wires came in contact,
blew out and tripped the breaker.
Long story short, I replaced the power cord connections,
re-assembled the motor and tested it.? It ran with no noises,
tripped breakers or any obvious complaint.
I got lucky and learned a lesson.? Don't walk away from a
running bandsaw.
|
Re: A mistake and recovery
I did have the thought of adding a thermal cutoff (they are pretty cheap) but it occurred _after_ I put the motor back together.? It was such a pain to re-install the motor I will have to wait awhile until the pain is a distant memory before I do that.
Omissions like that are pretty irksome.? Some time back the motherboard on one of our computers blew up because the manufacturer saved $1 by using a cheap fan instead of a good one.? Same deal here, a thermal cutoff costs less than $1.
|
Re: A mistake and recovery
You got lucky. The inexpensive motors on many of these saws don’t usually have thermal motor protections so you need to be particularly careful. I don’t use sacrificial stock. I just make sure that the shutoff switch is adjusted properly
to shut the saw off at the end of the cut. I am careful to manually hold the blade up off the workpiece until it is up to speed to make sure that it doesn’t get snagged on something and stalls before starting to cut. This is a particularly good idea when cutting
rebar or other rough finished stock. And, I don’t let the saw run unattended; keeping within hearing distance is a good practice in case something goes wrong.
?
I’m glad it worked out for yoou.
?
Sent from for Windows
?
|
Re: A mistake and recovery
In this case luck prevailed, assisted by determination and patience. Well done!
Sometimes I will walk away from my bandsaw when cutting LARGE material, but never very far. I always remain within earshot so I can hear it running.
I NEVER walk away from a machine that has no automatic stop or shutoff, like my Craftsman lathe. To do so is an invitation for disaster.
?- Raymond
|
Re: A mistake and recovery
Hi, a very good selution for your problem with a satifying end.
A few days ago I was cutting a small length of 1" square stock with my bandsaw.? I supported the piece on a sacrificial strip of aluminum to make sure it wouldn't tip down while being sawn.? The sacrificial piece was a bit narrower than the stock so I could grip it with the vise.? The mistake I made was to turn the saw on and then I left for a "quick" errand.? But that turned into a much longer interval -- so the saw was unattended.? Well, when I finally came back the saw had stopped, but that's because the cutoff piece had jammed the saw.? Probably because the sacrificial piece prevented the saw from immediately turning off.? The scrap got sucked into the bearing guides and jammed.
I didn't smell a burnt odor coming from the motor and the breaker for that outlet had tripped so I was hopeful that the saw was OK, but that turned out to not be the case.? With power restored and the jam cleared, the motor clearly was dead.? My ohmmeter showed an open connection.? It wasn't the switch which only left the motor as the location of the open circuit.
I found that Harbor Freight claims to have replacement bandsaw motors but they're about $150 so I thought it was worth my time to see if I could fix the motor.? I found an online forum where someone had repaired theirs by replacing a thermal cutout located inside the motor housing so......maybe I might get lucky.
I removed the motor and took off the end nearest the power cord connection but unfortunately my model had no thermal cutout.? Still no bad burnt odor and the windings looked OK so I used my ohmmeter some more to see if I could locate the open connection.? I had to remove the heat-shrink tubing from the power cord-to-windings connections and noticed that the hot and ground return wires were stuck together.? More examination revealed that they were melted.? ?They had been tied very tightly by some kind of string so when the motor got hot enough to soften the insulation the wires came in contact, blew out and tripped the breaker.
Long story short, I replaced the power cord connections, re-assembled the motor and tested it.? It ran with no noises, tripped breakers or any obvious complaint.
I got lucky and learned a lesson.? Don't walk away from a running bandsaw.
|
John Vreede
davesmith1800