Power pro problems and no response from SS

[DLB]

Just getting back into turning, now more seriously and am experiencing this setscrew loosening on the faceplate issue big time. What ended up working for you Gavcon?

hal

There has been a lot of discussion on setscrews coming loose on PowerPros in the past. The problem seems more prevalent on some machines than others, either they are different or the way they are used is different. The only issue I've had is my motor pulley was not positioned correctly on the shaft, it either moved or was not installed correctly to begin with. I followed the 'advice' from the SS PowerPro Wiki page and put loctite on both the pulley and fan setscrews. IMO this should be done for all, not only if there is a problem. IIUC the current waveform from the power supply is 'timed' to the motor so even a small error in fan position seems like big trouble.

Does your faceplate have the angled setscrew as discussed earlier in this thread and elsewhere such that it is perpendicular to the tapered flat? (Mine don't, I don't know that faceplates with them exist.) What speed and how heavy are you turning? Is the setscrew coming loose when it is just turning or only when you have a chisel engaged? Weight - I'm just curious. At low speed there is generally more RPM error so more correction being applied.

Is it possible that the female threads in your faceplate are just worn to the point that it won't work?

- David

[hfmann]

Thanks David,

I think problem is solved. Perhaps elsewhere in this thread there was mention of the tapered spindle and faceplates whose hole wasn't tapered. I compared the small faceplate I was using to another dark heavy one in my drawer. I found the one in use wasn't tapered, and the dark heavier one was. That sent me to the Shopsmith store to see what their faceplates looked like. The SS store one appeared dark and heavy like my unused one. The one I was using was much lighter and very shiny metal of some sort. I'll bet I got that one through Ebay. I switched out the faceplates and BINGO. At this point, no slippage. Hurray! I suspect I bought this dark gray one from the Shopsmith store some time agol

Regarding my turning. My pieces are rather light at this point, perhaps the blanks are a couple of pounds. I don't know exactly when the setscrew becomes loose enough for the faceplate to rotate on the spindle. When I'm turning, I'll notice it get rougher and rougher and vibration increase. Then I stop the machine and find the setscrew is no longer aligned with the the spindle collar. I turn as fast as it'll go without vibration. Today it meant I was starting at 500 and got up to 1300 once everything was round.

thanks,

hal

[JPG]

My guess is that the lighter shiny one is aluminum and the dark heavy one is cast iron. That would explain the original problem re female threads!

[hfmann]

JPG - so are you thinking the aluminum is softer and likely to slip under pressure?

[wa2crk]

I had a couple of set work loose in the past. What I did is put a small amount of RTV on the threads of the set screw and let it cure. Then re-install the screw, the RTV will hold the set screw ok and you can loosen the set screw several times before renewing the RTV.
I think that the rapid switching of the motor causes a vibration that is not apparent to the user but may be causing the set screws to loosen.
Bill V

[chapmanruss]

hal,

Both of your faceplates are likely Shopsmith ones. Over the years the Lathe Faceplates, both 3-3/4" and 6" have changed from cast iron to aluminum and back to cast iron. Below is a picture of the different 3-3/4" Lathe Face Plates. the one on the left is a cast Iron faceplate from the Model 10's. The two in the middle are aluminum. The one on the right is back to cast iron and is the current one.

_

3 3-4 inch lathe faceplates.jpg (76.87 KiB) Viewed 4398 times

[hfmann]

Hey Chapmanrus,

That is so helpful. I assumed the aluminum one was one I bought off ebay and wasn't official Shopsmith.

Now - that brings me back to wondering why it's not locking down on the spindle anymore.

thank you.

hal

[JPG]

JPG - so are you thinking the aluminum is softer and likely to slip under pressure?

Also wear.

[wurlitzerwilly]

I had this problem many years ago, with the bandsaw coupler. I tried Loctite and a new coupler, but still that sucker came loose!

I contacted SS and spoke with Wes (at that time) which eventually resulted in a phone call and instructions on how to adjust the PowerPro software for over/undershoot. If you can't get SS to tell you how to do it, I might still have the instructions somewhere, although I was asked not to publish them, as tinkering with that thing without knowing what you're doing could result in headstock destruction or injury.

What was happening was that the PowerPro senses under-speed and applies pulses to speed up. It can then over-shoot resulting in pulses being removed to slow it down again. If this hysteresis period is at a certain frequency, it sets up an oscillation in the system at the resonant frequency of the set screws and they start to undo.

I adjusted mine and do not notice any difference in performance, but those dang set screws have never come undone again.

[hfmann]

Interesting Wirlitzerwilly. Thanks for that info.

hal