Balancing a Bandsaw

[Jim Chilenski]

I finally decided to try and repair my old iron 1945 Delta 14" bandsaw, model 892 (?) serial # 39-8027. Ever since I have owned the machine there has been a slight vibration when running at wood cutting speed. I was able to smooth it out some by adding lead solder to the blade wheel and wrapping it with metalic duct tape. This has worked for awhile but has always left a little vibration that I can feel when cutting on this saw. So I started to tear into it this afternoon. I took off the upper frame assembly, the table, the motor, pulled the direct drive pulley, and removed the reduction gear box. But I can't get any further. I can remove the lower blade wheel but can't get the direct drive shaft to slide out of the drive gear that engages the reduction drive system. One of the parts diagrams on Acetoolrepair shows that there is a collar with a set screw that holds the gear to the shaft, but I can't figure out where it is located.

So here is what I am finding. The drive gear can be rotated on the shaft by about 1/2 of a degree. This I found by grabbing the gear and trying to rotate it while holding onto the lower blade wheel. Also if I rotate the shaft either with the lower blade wheel on it or removed it will always stop with the key way of the drive pulley pointing down. This makes me believe that the imbalance is related to the drive gear that engages the reduction drive. But I stuck on how to proceed.

The two photos show the wheel side of the base and the input side of the base with the reduction transmission removed. I have not found any teeth missing from the drive gear and there weren't any broken parts in either the transmission or the base.

Any suggestion from anyone who has rebuilt one of these?

Jim

48098

48099

[Jim Chilenski]

OK! Had success in getting the shaft assembly out of the base. I found the set screw that was holding the collar for the drive gear. Once I removed the screw it was a simple matter to tap the shaft through the drive gear and out of the base. A visual inspection of the shaft, gear, collar, etc shows no damage. None of the teeth on the gear are damaged and I can't understand why the assembly acts as if its out of balance.

Now for another question. I have never dealt with an equipment repair shop before, however I supposedly have a good one available in the Columbus area. Can a machine shop balance a shaft assembly without it being in a housing? In other words should I put this thing back together and pay for the repair shop to disassemble the base of the saw. Or can I just take them the shaft with the gear, pulley, and lower wheel and they could balance it? I would just want them to press the wheel side bearing off, replace both bearings, and then balance the whole assembly. Am I being unreasonable? And in discussing this with them what should I ask for?

Thanks,
Jim

48140

48141

[Brad Noble]

Jim,

Which repair facility in Columbus are you thinking about? You may PM me if you'd prefer. I'm only about 30 miles from you but know a couple guys (fellow woodworkers) in Columbus that may be able to help on this one.

Brad

[Cliff Rohrabacher]

A visual inspection of the shaft, gear, collar, etc shows no damage. None of the teeth on the gear are damaged and I can't understand why the assembly acts as if its out of balance.
It could be the free movement you discovered on the drive gear. Or it could be that something is out of balance.



Can a machine shop balance a shaft assembly without it being in a housing?
Yes assuming they have balancing wheels. Large metal wheels on smooth bearings in an assembly that you set on a level granite plate. You give the item to be balanced a spin and watch which section of the thing settles to the bottom as it comes to rest. It's a slow process.

If you take it to a shop with an electronic balancer it'll be way fast. Machine shops tend not to have those.

I have worked in rather a large number of machine shops and I have only seen a balancing unit once.
It was with Arthur D. Little's research shop where cost was never an issue.

I think you are going to have to spend some time looking for a shop with balancing capability.

Automotive shops tend to have equipment that is specially made for a dedicated purpose such as camshafts, cranks, wheels etc.



In other words should I put this thing back together and pay for the repair shop to disassemble the base of the saw. Or can I just take them the shaft with the gear, pulley, and lower wheel and they could balance it?
So long as they won't be responsible for the assembled unit and just for the very narrowly defined job of balancing you can give 'em component parts.
No need to pay them to take it apart.



I would just want them to press the wheel side bearing off, replace both bearings, and then balance the whole assembly.
That sounds fine.

[Jim Chilenski]

Thanks Cliff!

That is what I was hoping to hear. I'm planning on taking the shaft, pulley, gear, and wheel to my local Delta service center. I will call them Monday to confirm that they can do the work I'm requesting. Your suggestion that the imbalance could be from the movement in the gear is a possiblity. It seems that the side of the key that fits into the keyway on the gear is slightly worn but I've misplaced my micrometer and can't confirm this. My service center should be able to confirm this as well. I just hope that the keyway in the gear isn't worn.

Thanks again for your advise.

Jim

[Jeff Horton]

Jim, I know someone that just has two of these saws and is parting one out. If you interested send me a Private Message and I will get you two in contact.