Bandsaw and the PowerPro

michaeltoc · Post by **michaeltoc** » Sat Oct 15, 2011 9:28 am

Many of us have had issues with the band saw making banging noises with the PowerPro. After talking with Wes and adjusting the settings it got better, but not good enough. suspecting that backlash is causing the PowerPro to jump around, I did an experiment.

I tried resawing a piece of 2x6, and confirmed the noise. In place of the SPT coupler I used a clamp-style rigid shaft coupling. This has the added benefit in that I could get the bandsaw and the headstock perfectly aligned. I slipped on the coupler, locked down the headstock, then loosened the SPT lock and the setscrews that lock the bandsaw tubes. I tightened the shaft coupler while "wiggling" the bandsaw so that it would align perfectly.

I tested the setup and I could resaw without any banging noise! Suspecting that misalignment may be the cause, I reinstalled the SS power coupler, and the banging came back. I put the rigid coupler back on, and the banging stopped.

I also tried a Ruland curved jaw-type coupling with a hytrel spider (for high torque). I did not use a standard Lovejoy, as they have some degree of backlash, and the Ruland claims that it is "zero-backlash". It worked like a charm!

dusty · Post by **dusty** » Sat Oct 15, 2011 9:59 am

michaeltoc wrote:Many of us have had issues with the band saw making banging noises with the PowerPro. After talking with Wes and adjusting the settings it got better, but not good enough. suspecting that backlash is causing the PowerPro to jump around, I did an experiment.

I tried resawing a piece of 2x6, and confirmed the noise. In place of the SPT coupler I used a clamp-style rigid shaft coupling. This has the added benefit in that I could get the bandsaw and the headstock perfectly aligned. I slipped on the coupler, locked down the headstock, then loosened the SPT lock and the setscrews that lock the bandsaw tubes. I tightened the shaft coupler while "wiggling" the bandsaw so that it would align perfectly.

I tested the setup and I could resaw without any banging noise! Suspecting that misalignment may be the cause, I reinstalled the SS power coupler, and the banging came back. I put the rigid coupler back on, and the banging stopped.

I also tried a Ruland curved jaw-type coupling with a hytrel spider (for high torque). I did not use a standard Lovejoy, as they have some degree of backlash, and the Ruland claims that it is "zero-backlash". It worked like a charm!

If you are saying that the unwanted noise (chatter) is being emitted by movement within the power coupler, I would be concerned the movement (which causes the chatter) is simply being moved to another location along the drive line.

Something is being stressed by that movement being produced at the PowerPro Headstock.

If I was a PowerPro owner, I would be bugging Shopsmith for some sort of guarantee that this "noise" was not the result of something that will one day take a toll on the drive line.

I have an extensive background in environmental testing, including vibration and mechanical shock. Based on that background, I am here to say that some day something has got to give.

JPG · Post by **JPG** » Sat Oct 15, 2011 10:39 am

dusty wrote:If you are saying that the unwanted noise (chatter) is being emitted by movement within the power coupler, I would be concerned the movement (which causes the chatter) is simply being moved to another location along the drive line.

Something is being stressed by that movement being produced at the PowerPro Headstock.

If I was a PowerPro owner, I would be bugging Shopsmith for some sort of guarantee that this "noise" was not the result of something that will one day take a toll on the drive line.

I have an extensive background in environmental testing, including vibration and mechanical shock. Based on that background, I am hear to say that some day something has got to give.

The DVR motor creates extreme torque pulses and as such will indeed put the entire drive train under a stress 'test'.

If all is tightly joined, I do not think a catastrophe will eventually occur.

That sloppy plastic forgiving shopsmith coupler on the other hand does not meet that new criteria.

I think an 'improved' quick on/off coupler design is indicated!!!!!!!

Although a 'new' unused current design coupler may 'work', it will degenerate eventually IMHO.

dusty · Post by **dusty** » Sat Oct 15, 2011 10:44 am

Am I correct in the assumption that the problem with the coupler is that the splines on the coupler wear and become loose in the mating grooves in the hubs?

wurlitzerwilly · Post by **wurlitzerwilly** » Sat Oct 15, 2011 10:44 am

dusty wrote:If you are saying that the unwanted noise (chatter) is being emitted by movement within the power coupler, I would be concerned the movement (which causes the chatter) is simply being moved to another location along the drive line.

Something is being stressed by that movement being produced at the PowerPro Headstock.

If I was a PowerPro owner, I would be bugging Shopsmith for some sort of guarantee that this "noise" was not the result of something that will one day take a toll on the drive line.

I have an extensive background in environmental testing, including vibration and mechanical shock. Based on that background, I am hear to say that some day something has got to give.

I just did a test run with mine.

I already had a 1/2" blade installed and I used the chart setting for that and for softwood.

The cut was not as smooth as I expected but I think that may be due to distortion on the blade where I forgot to release the tension last time I used it. I'm sure it has nothing to do with the Power Pro.

I got part way through the 2nd cut and suddenly the blade stopped moving, but the headstock was still running and out of habit, I hit the off switch real fast! I removed the wood from the blade and turned the headstock on again, which immediately got back up to its previously set speed, but the blade didn't turn. A check revealed that the coupler was not connecting the headstock to the bandsaw drive. At first I thought I'd forgotten to tighten the headstock on the way tubes, but that was not the case. What had happened, quite by coincidence is that the drive coupling on the bandsaw shaft had come loose and drifted back up the shaft, disconnecting itself from the coupler. A re-set and all is well.

I noticed a little vibration/slight rocking when I oveloaded the blade, which I guess is the Power Pro trying to compensate. Taking things more easy and the cut was fine.

I must write 1000 times "I must remember not to force the wood past the blade too fast", a bad habit of mine.

michaeltoc · Post by **michaeltoc** » Sat Oct 15, 2011 2:22 pm

dusty wrote:Am I correct in the assumption that the problem with the coupler is that the splines on the coupler wear and become loose in the mating grooves in the hubs?

It's not so much that there is wear on the splines, but the coupler itself has enough flex to create backlash. One other test I did was to put hose clamps on the ends of the power coupler to lock it onto the hubs to eliminate any "slop". It didn't work, so the problem may lie with the plastic coupler itself. I think the problem is magnified because of the large wheels on the bandsaw (there is no problem with the jointer or planer using the standard power coupler).

I can't adequately describe how backlash affects a DVR motor - but it causes the motor speed to jump and jerk. This rapid speed changing has resulted in the drive hubs vibrating loose, and I even snapped a power coupler - things that have never happened to me in 25 years with a standard headstock.

Eliminating the backlash lets the PowerPro run smoothly.

wurlitzerwilly · Post by **wurlitzerwilly** » Sat Oct 15, 2011 2:47 pm

michaeltoc wrote:It's not so much that there is wear on the splines, but the coupler itself has enough flex to create backlash. One other test I did was to put hose clamps on the ends of the power coupler to lock it onto the hubs to eliminate any "slop". It didn't work, so the problem may lie with the plastic coupler itself. I think the problem is magnified because of the large wheels on the bandsaw (there is no problem with the jointer or planer using the standard power coupler).

I can't adequately describe how backlash affects a DVR motor - but it causes the motor speed to jump and jerk. This rapid speed changing has resulted in the drive hubs vibrating loose, and I even snapped a power coupler - things that have never happened to me in 25 years with a standard headstock.

Eliminating the backlash lets the PowerPro run smoothly.

Arguing against my own initial findings, I have just been doing some work with the bandsaw and the hub on the bandsaw came loose several times. I couldn't really hear any 'banging' but I put my hand on the headstock and I could detect a certain amount of thump.

I replaced the usual plastic coupler with a brand new one and there was some improvement. Well at least the bandsaw hub didn't get loose again.

I wonder if this coupler might solve the issue?

http://www.ebay.co.uk/itm/NEW-DESIGN-SHOPSMITH-MARK-V-POWER-COUPLING-KIT-UPGRADE-/320595188050?pt=LH_DefaultDomain_0&hash=item4aa4f65952

Michael, what coupler did you find that eventually worked well?

dusty · Post by **dusty** » Sat Oct 15, 2011 2:55 pm

michaeltoc wrote:It's not so much that there is wear on the splines, but the coupler itself has enough flex to create backlash. One other test I did was to put hose clamps on the ends of the power coupler to lock it onto the hubs to eliminate any "slop". It didn't work, so the problem may lie with the plastic coupler itself. I think the problem is magnified because of the large wheels on the bandsaw (there is no problem with the jointer or planer using the standard power coupler).

I can't adequately describe how backlash affects a DVR motor - but it causes the motor speed to jump and jerk. This rapid speed changing has resulted in the drive hubs vibrating loose, and I even snapped a power coupler - things that have never happened to me in 25 years with a standard headstock.

Eliminating the backlash lets the PowerPro run smoothly.

The momentary reversals of applied toqgue result in greater stress on the coupler than does a constant applied force. It is not surprising to me at all that a coupler might break (especially an older coupler).

I have used the same couplers for these many years and have lost two in the last couple months. That plastic (actually I think it is nylon) will eventually give up.

The force that you were willing to put on the couplers by using clamps was probably not enough to affect a change in gripping force applied to the hubs. That small circle of nylon just did not collapse much under the pressure of that clamp. (My "Prognosis by Proxy" - worth exactly what you are paying for it)

How about those prices that tristateauto (ebay seller) charges. I made a price comparison on five items that tristateauto sells that are also available elsewhere. Based on that comparison, I quickly decided that tristateauto would NOT become my go to source. However, I must admit - he is an entrepreneur. Some of that items that he offers are available from very few sources and he recognizes a captive customer base when he sees US.

wurlitzerwilly · Post by **wurlitzerwilly** » Sat Oct 15, 2011 3:28 pm

dusty wrote:The momentary reversals of applied toqgue result in greater stress on the coupler than does a constant applied force. It is not surprising to me at all that a coupler might break (especially an older coupler).

I have used the same couplers for these many years and have lost two in the last couple months. That plastic (actually I think it is nylon) will eventually give up.

The force that you were willing to put on the couplers by using clamps was probably not enough to affect a change in gripping force applied to the hubs. That small circle of nylon just did not collapse much under the pressure of that clamp. (My "Prognosis by Proxy" - worth exactly what you are paying for it)

How about those prices that tristateauto (ebay seller) charges. I made a price comparison on five items that tristateauto sells that are also available elsewhere. Based on that comparison, I quickly decided that tristateauto would NOT become my go to source. However, I must admit - he is an entrepreneur. Some of that items that he offers are available from very few sources and he recognizes a captive customer base when he sees US.

I appreciate your thoughts on TriStateAuto but I wonder what the alternative is?

If you've lost a two or more plastic couplers, what did you replace them with or is there another solution?

dusty · Post by **dusty** » Sat Oct 15, 2011 5:02 pm

wurlitzerwilly wrote:I appreciate your thoughts on TriStateAuto but I wonder what the alternative is?

If you've lost a two or more plastic couplers, what did you replace them with or is there another solution?

There are some other coupler solutions, that I have never tried or even laid hands on, but I had purchased two new couplers from Shopsmith that are now in-service. For use with the PowerPro, I have no experience there so I have no ideas of value to offer.