G0766 - erratic speed control?

[Brice Rogers]

When I get a replacement, I think I'll do a post-mortem autopsy on the component (I'm a retired electronic engineer). Mine was slightly erratic when I first got it and is getting noticeably worse as time goes on. I'm wondering about the issue where Grizzly is on back-order with the part - - I'm wondering if it is just a situation where they didn't do a particularly good job of planning/ordering or if this is an indication that the potentiometers came from a bad lot. But it is a cheap part and should be easy to replace.

It is re-assuring that others have had similar problems and that it is unlikely that it is a controller issue. I'm appreciative of all of the comments.

[Mark Greenbaum]

Roger: Thanks for the tip - I checked the screw on the pot, and it had gone missing. Luckily I had another knob almost identical to it in my guitar parts, so I robbed that screw, then I found the original screw in an unfinished walnut bowl. Now it's secured, and zero is easy to find, and about 1.5 - 2 turns of the pot takes it to full speed.

Mark......sounds like your pot is bad or the knob is spinning on the shaft.......make sure the set screw is tightened down against the shaft on the knob or is not missing altogether. Ten revolutions is not normal! You may need to call tech services and get a replacement if the potentiometer is bad.

Additional: Mark, I just went out to the shop and checked mine. The full rotation of the knob on the pot is a little less than one complete rotation from starting at zero rpm to 3200 + rpm. Either your set screw is lost or loose, or you have a bad pot. Know that the potentiometer is usually one of the weakest parts on lathes.......pot problems happen to other makes as well. Grizzly can fix this for you if it is bad.

[Brice Rogers]

Roger: Thanks for the tip - I checked the screw on the pot, and it had gone missing. Luckily I had another knob almost identical to it in my guitar parts, so I robbed that screw, then I found the original screw in an unfinished walnut bowl. Now it's secured, and zero is easy to find, and about 1.5 - 2 turns of the pot takes it to full speed.

Hello Mark, on my G0766, it is what is called a "one-turn pot". I think that it has something like 300 degrees of rotation. You mention turning yours up to two turns (720 degrees) - - is this correct?

[Bill Boehme]

For the old carbon element and wirewound pots, the standard rotation was 270°. After conductive plastic pots came along as well as component miniaturization, there are a number of different rotation angles depending on size, brand, and style so now the number can range from 270° to as much as 314°. However, most pots have a rotation angle of either 270° or 300°. Check the spec sheet for candidate pots to get the exact rotation angle.

[Mark Greenbaum]

Hello Mark, on my G0766, it is what is called a "one-turn pot". I think that it has something like 300 degrees of rotation. You mention turning yours up to two turns (720 degrees) - - is this correct?

I just checked the rotation of the pot, and I stand corrected - it is only about 270 degrees.

[Brice Rogers]

For the old carbon element and wirewound pots, the standard rotation was 270°. After conductive plastic pots came along as well as component miniaturization, there are a number of different rotation angles depending on size, brand, and style so now the number can range from 270° to as much as 314°. However, most pots have a rotation angle of either 270° or 300°. Check the spec sheet for candidate pots to get the exact rotation angle.

Yes, that makes sense and matches with my own recollection. That is why I was surprised by Mark's comment that he required 1-1/2 to 2 turns to get to full speed. I believe that Mark has the same lathe (G0766) as I do and that it is only a few months old. So the reason for my question is to learn whether he has a unique component in his lathe or was mistaken when he was typing.

However, thanks for your comment.

[Roger Chandler]

Just an observation about the potentiometer on this lathe. My former G0698 has the same headstock configuration as the G0766, and the pot on that lathe never gave me a minutes trouble......it always performed its function for the 5+ years I had it, and now it is working fine at our club.

The pot on my G0766 feels like it is a more substantial unit. It has more refined feel when turning it......meaning a tighter [read that as no slop] and just has a better feel over all. I get the sense that my former lathe's pot was not as good a unit as the one on the G0766...........that remains to be seen over time, but the one on this G0766 just seems better overall to me.

[carl mesaros]

For the old carbon element and wirewound pots, the standard rotation was 270°. After conductive plastic pots came along as well as component miniaturization, there are a number of different rotation angles depending on size, brand, and style so now the number can range from 270° to as much as 314°. However, most pots have a rotation angle of either 270° or 300°. Check the spec sheet for candidate pots to get the exact rotation angle.

Just for information, my new Laguna 2436 requires 10 complete turns from min to max rpm.
I found this quite a change from my Jet 1642. (270 degrees) Now that I have turned on this lathe for 8 months it's actually a nice feature. You can really fine tune your rpm!