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Bandsaw Vibration - Frustrated

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Forum topic by Grady posted 11-08-2013 02:51 AM 1314 views 0 times favorited 23 replies Add to Favorites Watch
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Grady

16 posts in 1032 days


11-08-2013 02:51 AM

Hey all,

I received an old bandsaw that I finally brought home from my grandfather’s shop about a month or two ago. It’s an old 12” craftsman bandsaw, but it didn’t have a stand anymore. I bought a “universal stand” from harbor freight, which turns out it wasn’t universal of course.

When I have the bandsaw up and running I get a pretty significant vibration that I have no clue how to get rid of. It gives me a pretty rough finish on anything I cut because the blade bounces around. I’ve replaced the belt, and made sure the blade guides and everything are tracking correctly. What else can I try? Here are some pictures of the setup and the modifications I did to the bandsaw stand.

The motor my grandfather gave me appears to be running backwards which is why I have it hanging over the side. I can’t seem to get the tension I want in the belt because the motor is leaning slightly back. I’ve bolted down the front of the motor as tight as I can, but I’m not sure if it’s tight enough.

Thanks!


23 replies so far

View JustJoe's profile

JustJoe

1554 posts in 791 days


#1 posted 11-08-2013 03:11 AM

Let’s see what we’ve got here…
You’ve mounted this tall thin saw on a skinny little base that is probably made of some exotic tinfoilluminum alloy. Every corner and connection is a bolt or screw, so you’ve got about 300 different places to get something loose and get vibration started.
Then you’ve got that funky little motor thing going – you hung the heavy moving item halfway off the back, throwing what little balance you had out the window. It’s only secured in the front so you can’t get proper tension on the belt which is probably a bit stiff so every time it goes around the pulley it jumps up and down and well you can see the results.

If you’re determined to make this work, then you might start by stiffening up that stand – put some cross-braces on it and secure the bottom and top shelves on all four sides with snug bolts. Get it sturdy enough that a passing mosquito can’t fart on it and send it toppling over. Maybe replace those thin little shelves with some real wood – something manly like a 2×8 or 2×12 glued up to size.

Then take the motor and flip it upside down. Mount it to a board and put the board on a hinge underneath the top shelf. That means the weight of the motor is in the middle of that contraption, not hanging its butt out the back end. And the weight of the motor hanging down will provide some tension on the belt.

Change the belt out for a link-belt so you don’t have any stiff areas causing a vibration when they hit the pulleys. HF used to sell them, they still might. Then once you’ve got the motor hanging underneath the top shelf you’ll have space on that bottom shelf to put something with a bit of weight – even if it’s just a couple of bags of sand it would be better than what you’ve got.

good luck.

-- This Ad Space For Sale! Your Ad Here! Reach a targeted audience! Affordable Rates, easy financing! Contact an ad represenative today at JustJoe's Advertising Consortium.

View Tedstor's profile

Tedstor

1506 posts in 1385 days


#2 posted 11-08-2013 03:11 AM

A long belt like that can cause vibe. You’ll likely lose power too. AND the tension will be tough to adjust.
Can you mount the motor to the underside of the piece of plywood that the saw is attached to? That way a smaller belt can be used?

Poorly balance wheels or worn tires are another cause of excessive vibe.
but Joe, as usual, summed it up in his typical, elequent fashion :)

View robscastle's profile

robscastle

1881 posts in 957 days


#3 posted 11-08-2013 03:31 AM

Hello Grady,

Without stating the obvious did you ask your grandfather to inspect it for you?

I don’t believe the problem is within the stand but check it anyway, you never know.

There are some tests you can do to isolate the source of the vibration:

Static no run tests.

Remove the drive belt, band saw blade and spin by hand all the moving parts, motor upper and lower wheels, and any bearing guides fitted.
If they do not spin freely or make a odd noise there is a binding problem somewhere, possibly a bearing, so gently rock each item and check for abnormal movement, this checks bearings, bearing mounts and general moving parts.
Examine the blade and belt for any abnormal lumps and bumps.
Everything seem OK?

Pulley and wheel alignment:
Using a straight edge check the drive components are correctly aligned, you can also do this visually by looking along the belt pulley to pulley, there should be no obvious difference in the areas where the belt leaves the pulley and enters the other pulley.
Is that wooden mounting bases I see? The fault may well be in there.

Then do some dynamic tests.
If you have one change the blade and do another dynamic test. Put the original belt back on and run it again.

Still there?

then
1. Run the saw fully functional and see if there is any odd visible movements and audible abnormal noises while it is running,
a. Check the belt and watch if its oscillating or oscillates randomly, regardless of the fact its new.
b.Open the doors, run the machine, while keeping fingers away and do the same again checking for abnormal movement or noises.

If that doesn’t localise the vibration remove the belt and run the machine, if its gone its in the drive train somewhere. If its still there the vibration is in the motor.

Remove the blade this time and run the machine again if the vibration is still there is within the motor, drive belt or lower band saw wheel. If its gone its in the upper Band saw blade wheel.

If everything seems OK but still vibrates one of or both the blade wheels have thrown their balancing weights.

These are small metal clips attached to the inner part of the wheel, if they are missing there will be a witness mark from where they should be.

-- Regards Robert

View Jimbo4's profile

Jimbo4

1183 posts in 1515 days


#4 posted 11-08-2013 04:16 AM

HF sells the link belt, green in color, made in Italy – NOT CHINA.

-- *Arachnoleptic Fit*: The frantic dance performed just after you've accidently walked through a spider web.

View Loco's profile

Loco

210 posts in 502 days


#5 posted 11-08-2013 07:48 AM

Those are decent bandsaws. It’s old enough to just go ahead and put bearings, tires, re-evaluate the guides, get the motor mounted closer to the pulley, throw that P.O.S. stand in front of a moving truck and make one( WTF were you thinking ?). Here’s your belt. http://www.fennerdrives.com/powertwist-derivatives/

-- What day is it ? No matter. Ummmm What month is it ? No moron. I paid for a 2 x 6. That means Two inches by six inches. I want the rest of my wood.

View bigblockyeti's profile

bigblockyeti

1813 posts in 473 days


#6 posted 11-08-2013 03:34 PM

Can you get a closer picture of the motor? Most A/C motors can be reversed by a simple rewire. There are a few Chinese ones that don’t offer this ability, but they are usually not found (or used) on wood working tools.

View dhazelton's profile

dhazelton

1282 posts in 1049 days


#7 posted 11-08-2013 04:10 PM

You say the blade bounces around – as in side to side? for and aft? That sounds like the blade tension is wrong and/or you don’t have the blade guide down close to the wood. Also if you are trying to cut thick wood with a fine thin blade it will wander. I would unplug the machine, open the covers and watch the wheels and blade as you turn the wheels slowly by hand. Put a straightedge against the face of the wheels to make sure they are in alignment. If the blade doesn’t track close to the center of the wheel (a little forward is ok) then you need to tighten up the tension. Try to wiggle the wheels to see if there is play in the bearings. Build a beefier stand (2X4s is fine), get a shorter belt and just do a tune up on the thing and use the appropriate blade for the stock and you should be fine. Urethane tires can be had on ebay for $20-$30 too.

View Sylvain's profile

Sylvain

590 posts in 1252 days


#8 posted 11-08-2013 08:37 PM

Have a look at :
http://www.emachineshop.com/machine-shop/Dynamically-Balancing-Flywheels/page187.html

a dial indicator is not mandatory; a mirror glued with double sided tape, a ray of light and some (white) board to which the light will be reflected on

or something more intuitive :
http://wiki.vintagemachinery.org/Default.aspx?Page=BandsawBladeBalancing&AspxAutoDetectCookieSupport=1

the light ray method is also applicable with this second method.

-- Sylvain, Brussels, Belgium, Europe - The more I learn, the more there is to learn

View Sylvain's profile

Sylvain

590 posts in 1252 days


#9 posted 11-08-2013 08:54 PM

have also a look here:
http://americanwoodworker.com/blogs/techniques/archive/2008/09/12/Q-A.aspx

-- Sylvain, Brussels, Belgium, Europe - The more I learn, the more there is to learn

View Surfside's profile

Surfside

3372 posts in 926 days


#10 posted 11-08-2013 09:42 PM

Remove the drive belt and turn the machine on.
This will let you know if the vibration of your band saw is from the motor or because of the way it is mounted. If there is no vibration

during this process, then you know that it is not from your motor and/or the way you mounted, balanced and secured your machine.

Put the drive belt back on and take the blade off.
This will let you know (if the vibration continues) that the problem may come from the following: drive belt (tension), the alignment

of your pulley, lower wheel(bearings and/or the balance)
Try running the saw with and without the blade. Check if there’s difference . The problem might come from the blade
(a bad weld can cause vibration and/or twisted)

-- "someone has to be wounded for others to be saved, someone has to sacrifice for others to feel happiness, someone has to die so others could live"

View Grady's profile

Grady

16 posts in 1032 days


#11 posted 11-08-2013 09:43 PM

Thank you for all the feedback and quick answers. Just to answer a few:

1) My Grandfather passed away about 20 years ago. This stuff has been sitting in the shop he had since that time, so I couldn’t ask him how he had it set up. It was turned into a storage shed, so the stand it used to be on is long gone.
2) For the “what were you thinking” questions, honestly I don’t know any better. Like I said I’m just getting started in the hobby with no background in woodworking or the tools. Just trying to figure it out as I go.
3) Most of the pictures I found online of this type of setup did have the motor hanging off of a bracket underneath. However, maybe I’m not thinking clearly but since the motor is running backwards I can’t mount it like that can I?

Thanks for all the info, I’m going to try and work up something to fix these issues in the next week or so.

View toddbeaulieu's profile

toddbeaulieu

413 posts in 1757 days


#12 posted 11-08-2013 09:49 PM

I have a different approach than the previous suggestions. Assuming nothing is wrong, you can still get vibration in these old saws. I have an old Grizzly that was awful when I fired her up. My fix to vibration problems of many types is dynamat. It works fantastically on bathroom ceiling fans, car doors that rattle from the cheap speakers, and in your case band saws.

The product is a foil backing with a tar-like film that’s sticky. It’s a vibration damper. It adds weight and vibration absorbtion, both important. Dynamat is a brand name, but I’m sure you can find other similar solutions. For instance, I noticed that some water table sheild (comes in a roll) that I recently used was quite similar, but with plastic backing instead of foil.

I stuck a few pieces in various key places on my top shield, bottom shield and on the power/motor box on the back. BAM! She purrs with zero noise!

Years ago I used it on a fancy car stereo project and had a left over box of it. I’ve been nibbling at it ever since and it’s never let me down.

View hydro's profile

hydro

208 posts in 504 days


#13 posted 11-09-2013 09:18 PM

Grady, I had one of those saws for many years, and most likely the problem is your blade. In fact, I worked for Sears when I bought the saw, straight out of the “defective return” stockroom. The customer had purchased it along with the Sears service agreement. It vibrated very badly and the tag reads that service had been out twice to diagnose the issue without any success. I looked at it, pulled the cover off and gave the wheel a spin, noting that the blade was welded crooked (front to back). I bought it, replaced the blade and used it for many years, without any subsequent vibration. It’s a great saw.

*Replace the blade and see what happens before doing the major modifications mentioned above.

-- Minnesota Woodworkers Guild, Past President, Lifetime member.

View Grandpa's profile

Grandpa

3211 posts in 1428 days


#14 posted 11-09-2013 10:57 PM

#3 for changing the blade. I have that saw and I have had blades that were so crooked that I might have made them up out back of the barn. Sad but true. I have had more than one bad blade. I have changed blade brands. I had a couple of bad bearings too. Right now I can’t remember which ones but I do remember my son took the number to the bearing store and got a hand full of new bearings. They are all the same and they were cheap to buy. Changed the saw entirely. Only took a few minutes to make the repairs.

View REO's profile

REO

669 posts in 827 days


#15 posted 11-10-2013 05:15 AM

ANY motor can be reversed even if it is not built to be consumer oriented. check the motor and see if it has a wireing diagam somewhere. if it does often there is a sentance underneath about what wire needs to be changed to reverse rotation if not PM me and we can run through it.

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