PowerPro and Bandsaw

wasatch · Post by **wasatch** » Thu Aug 01, 2013 7:50 am

When I use my bandsaw on my Shopsmith with the PowerPro it acts weird, like the PowerPro motor computer and bandsaw don't like to work together. I also have a non- PP Shopsmith and the bandsaw works smooth with it. When the bandsaw is running on the PP, its like the PP computer powers the motor then coasts then powers it again making a clunking sound in the bandsaw(hard to explain). I understand the way the PP motor works, i just thought the SS guys would have this figured out before selling the PP motor. Have any of you experienced this problem?

jimthej · Post by **jimthej** » Thu Aug 01, 2013 8:42 am

There is a thread from about 18 months ago on here. I would look it up, but the only real fix is to call Shopsmith and set up an appointment to talk to the gentleman who will talk you through revising some of the programming.
I hope that didn't confuse you. I and several others had to do this.

JPG · Post by **JPG** » Thu Aug 01, 2013 10:32 am

wasatch wrote:When I use my bandsaw on my Shopsmith with the PowerPro it acts weird, like the PowerPro motor computer and bandsaw don't like to work together. I also have a non- PP Shopsmith and the bandsaw works smooth with it. When the bandsaw is running on the PP, its like the PP computer powers the motor then coasts then powers it again making a clunking sound in the bandsaw(hard to explain). I understand the way the PP motor works, i just thought the SS guys would have this figured out before selling the PP motor. Have any of you experienced this problem?

I think Chuckl would say "Yep:D "

Yes a call to SS is in order, but first, make sure ALL hub setscrews are really really tight and your coupler is not worn(sloppy(backlash)).

Any backlash in the drive train will lead to hunting and

Clunking:eek: .

The pp is constantly dropping the speed slightly to maintain minimal power to the motor(torque demand determination) and depending upon the amount of speed reduction, adjusts its output. So some minimal hunting is normal, but if backlash is present, the up/down speed variation will become worse. Actually I believe it is more complicated than that, but this is I believe a reasonable facsimile.

I would look for Chuck's thread, but you really do not need scare tactics at this point!:D

charlese · Post by **charlese** » Thu Aug 01, 2013 8:15 pm

Absolutely, YES!:eek: Call Shopsmith and tell them your issue and tell them you want to talk to Wes! Probably you can't get hold of him right off, but he will call you if you leave your number.

I'll add to this with a long thread. http://www.shopsmith.net/forums/showthr ... ht=bandsaw See post number 27. He had similar bandsaw problems as I did. My PowerPro needed three trips back to Shopsmith in order to end the banging problems.

But anyway call Wes!!!

SDSSmith · Post by **SDSSmith** » Fri Aug 02, 2013 12:44 am

charlese wrote:Absolutely, YES!:eek: Call Shopsmith and tell them your issue and tell them you want to talk to Wes! Probably you can't get hold of him right off, but he will call you if you leave your number.

I'll add to this with a long thread. https://forum.shopsmith.com/viewtopic.php?t=10546&highlight=bandsaw See post number 27. He had similar bandsaw problems as I did. My PowerPro needed three trips back to Shopsmith in order to end the banging problems.

But anyway call Wes!!!

What he said. The PowerPro should drive the bandsaw without chattering or knocking. The second trip back to Dayton resulted in a complete replacement of the guts of my PowerPro headstock. The results were dramatic and very satisfying, but they required persistence on my part.

Hopefully, you will luck out and it will only take a couple of control parameter adjustments.

Ed in Tampa · Post by **Ed in Tampa** » Fri Aug 02, 2013 1:05 pm

Again I can't imagine this problem still existing on new PP.

nuhobby · Post by **nuhobby** » Fri Aug 02, 2013 1:48 pm

Got to agree -- this is what turned me from a Shopsmith "FanBoy" down to a mere "Fan." I love this forum, love the machines, bought a lot of them. But I've made adaptations to keep away from design characteristics I would call marginal... like the stability-margin on the DVR control system when running the high-rotational-inertia bandsaw. I run my bandsaw on a separate 'mini' induction-motor station.

JPG · Post by **JPG** » Fri Aug 02, 2013 4:00 pm

nuhobby wrote:Got to agree -- this is what turned me from a Shopsmith "FanBoy" down to a mere "Fan." I love this forum, love the machines, bought a lot of them. But I've made adaptations to keep away from design characteristics I would call marginal... like the stability-margin on the DVR control system when running the high-rotational-inertia bandsaw. I run my bandsaw on a separate 'mini' induction-motor station.

A bandsaw has 'high "rotational" inertia'?

Methinks it is the lack of inertia that exacerbates the sloppy drive clunking.

Underdamped be the buzz word.

P.S. I am surprised it works as well as it does considering the vast load characteristics variation.

nuhobby · Post by **nuhobby** » Fri Aug 02, 2013 5:46 pm

[quote="JPG40504"]A bandsaw has 'high "rotational" inertia'?

Methinks it is the lack of inertia that exacerbates the sloppy drive clunking.

Underdamped be the buzz word.]

I call it high rotational inertia because if you've ever thrown a blade on the bandsaw upper wheel, it takes a long long long time for it to spin down! The physics formulas for moment-of-inertia "reward" masses placed far away from the axis of rotation, such as a large-diameter wheel. Given my PP instabilities early on were apparent only with the 12" disc-sander and the bandsaw (and not with low-rotational-inertia / small-diameter items such as lathe-pieces), I generalized that moment-of-inertia as a troublesome thing. Whether it's my "general" explanation or yours, or Nyquist stability formulae, or who knows what -- it's complicated, and I appreciate that -- maybe we can hash-out halfway between Indy and Lexington sometime

.

JPG · Post by **JPG** » Fri Aug 02, 2013 9:08 pm

[quote="nuhobby"]I call it high rotational inertia because if you've ever thrown a blade on the bandsaw upper wheel, it takes a long long long time for it to spin down! The physics formulas for moment-of-inertia "reward" masses placed far away from the axis of rotation, such as a large-diameter wheel. Given my PP instabilities early on were apparent only with the 12" disc-sander and the bandsaw (and not with low-rotational-inertia / small-diameter items such as lathe-pieces), I generalized that moment-of-inertia as a troublesome thing. Whether it's my "general" explanation or yours, or Nyquist stability formulae, or who knows what -- it's complicated, and I appreciate that -- maybe we can hash-out halfway between Indy and Lexington sometime ]

The sanding disc has inertia for sure!

The BandSaw requires such little 'power' to drive it I did not think it had had much inertia.

Point taken!;)