G0766 - erratic speed control?

[Brice Rogers]

When I first got my G0766 2 months ago, I noticed that sometimes the speed control was erratic. As I was turning it CW, it would speed up but it would sometimes stop. Now it seems to be getting worse.

When I first start up, I'll turn the speed control clockwise and it will start running at a low rpm. Then there may be a dead spot and it'll stop. If I advance the control further, it will restart. If I advance further, it may either speed up or stop. If I "wiggle" the speed control it seems to eventually respond. Today I was running at a low speed - - perhaps 400 rpm - - after a few seconds it stopped. When it stops, I often hear a clicking from the controller. I can get it restarted, but it is a growing irritation.

I suspect that I have a noisy potentiometer. It is a low-cost part. However, it is possible that it could be the controller. I am a bit reluctant to complain to Grizzly because the last time they sent me a new (complete) headstock it had "crappy" threads on the spindle. Also, I don't look forward to shipping back a 200 pound part. (BTW, last time I got involved with shipping something back, I ended up with a $1000 shipping bill from UPS. It was a mistake that Grizzly corrected, but there was an element of "hassle".)

My questions:
1. Are others having this problem?
2. If I pulled the cover to the controller, are there visual diagnostics that I could use?
3. Has anyone replaced their potentiometer (basically a variable resistor that controls the speed ?

[Roger Chandler]

No problems at all on my unit at this point. If I were you, since it is in the warranty period, I would speak with tech support, and if they want to swap out something, then insist that they personally inspect the part before shipping. Sounds like a bad potentiometer to me,, but it could besomething else......perhaps a loose wire on the inverter?

[Brice Rogers]

Thanks for the idea, Roger. I think that I might check the resistance of the pot (with the power turned off). Maybe that may help to isolate the source of the problem. I'd hate to have to send back another complete headstock. :-(

[Len Mullin]

Brice, call customer service before you do anything, you could end up losing the warranty due to your tampering. The machine has a warranty, use it!
Len

[Art Mann]

Yes, let Grizzly help you figure out what is wrong and then provide a free replacement part!

[Mark Greenbaum]

I also have had a quirky speed control issue. When I first turn on the unit, it usually take about 10 complete revolutions of the speed potentiometer to get movement at the spindle. If I stop the machine by turning to "O" from "F" then when I start back up by going back to "F" it's at the same speed I stopped at. I have the belt on the high speed which may be why it takes so many turns to get going, but it is odd to me to have to turn so many times. Probably just an ID-10-T error on my part.

Brice, I sure hope it's something very simple. I'd hate for you to have to get in the weeds again on this unit.

[Jack Lilley]

Mines been working fine so far.

[Roger Chandler]

I also have had a quirky speed control issue. When I first turn on the unit, it usually take about 10 complete revolutions of the speed potentiometer to get movement at the spindle. If I stop the machine by turning to "O" from "F" then when I start back up by going back to "F" it's at the same speed I stopped at. I have the belt on the high speed which may be why it takes so many turns to get going, but it is odd to me to have to turn so many times. Probably just an ID-10-T error on my part.

Brice, I sure hope it's something very simple. I'd hate for you to have to get in the weeds again on this unit.
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.

[Dexter Harris]

Potentiometer. Have replaced mine twice. Both times it started that way. Then when starting to turn the speed up it would immediately go to 933 rpms. Grizzly sent one, slow mail of course. I was down a week waiting for it. Then a couple of months later to my horror it happened again. Contacted Grizzly, they slow mailed another. I, then started to worry about the price of this part, knowing that I will be paying for parts soon. Neal at Grizzly said they only cost a few bucks and can be bought at Radio Shack . We don't have Radio Shack here but I did find one at an electronic parts store for $23. I'm hoping its a better quality part. Took the old one apart. Not much to it. A week later, the second one arrived and its still in the package unopened as a backup. By the way I have the go733 . I love it anyway.

[Roger Chandler]

Potentiometer. Have replaced mine twice. Both times it started that way. Then when starting to turn the speed up it would immediately go to 933 rpms. Grizzly sent one, slow mail of course. I was down a week waiting for it. Then a couple of months later to my horror it happened again. Contacted Grizzly, they slow mailed another. I, then started to worry about the price of this part, knowing that I will be paying for parts soon. Neal at Grizzly said they only cost a few bucks and can be bought at Radio Shack . We don't have Radio Shack here but I did find one at an electronic parts store for $23. I'm hoping its a better quality part. Took the old one apart. Not much to it. A week later, the second one arrived and its still in the package unopened as a backup. By the way I have the go733 . I love it anyway.

Dexter, I would like to invite you to join the Grizzly Green Monster Group [GGMG] 147 other members who use Grizzly lathes. You can find it at the community tab near top of page......click, then groups, and you will see it.

[Dexter Harris]

Thanks for the invite, Roger. I will definitely do it. From reading here, it seems that no matter what lathe you have, you.will at some point need to work on it. Thanks again.

[Dexter Harris]

The pot for my lathe is 10k. Not sure if it's the same for the go766.

[Roger Chandler]

The pot for my lathe is 10k. Not sure if it's the same for the go766.
Same one listed for the 0766 - I checked the parts list for the 0766 and it is $2.75 and out of stock at the moment, but it does give info where on perhaps could take the number and find it locally.

[Brice Rogers]

Same one listed for the 0766 - I checked the parts list for the 0766 and it is $2.75 and out of stock at the moment, but it does give info where on perhaps could take the number and find it locally.

I googled the part description: POTENTIOMETER WX110 B10K, and found that it is carried by a lot of different places including Amazon and eBay, etc.

[Roger Chandler]

I googled the part description: POTENTIOMETER WX110 B10K, and found that it is carried by a lot of different places including Amazon and eBay, etc.

I did the same thing ........should be an easy and inexpensive part to acquire.

[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!