G0766 speed control is whacked.

[Mark Greenbaum]

Today I was finishing up a walnut bowl and noticed the low end speed of the G0766 is whacked. From dead stop to about 80 rpm on low speed belt config, it's OK, but a hair above 80 rpm, and it shoot to 800 rpm. No in between. What should I do? I blew out the belt compartment and also to outside of VFR, but no change. HELP please.

[Fred Belknap]

Call Grizzly, they would be your best bet for good information.

[Ken Fitzgerald]

Have you tried disconnecting power, letting it set unpowered for a couple minutes and then reconnecting power? Some motor controllers need to have power removed to reset if they experience an error.

[Roger Chandler]

Today I was finishing up a walnut bowl and noticed the low end speed of the G0766 is whacked. From dead stop to about 80 rpm on low speed belt config, it's OK, but a hair above 80 rpm, and it shoot to 800 rpm. No in between. What should I do? I blew out the belt compartment and also to outside of VFR, but no change. HELP please.

Sounds like the speed potentiometer failed on you. It is a small, inexpensive part, and they will replace it. If I were you, I would try to unplug the lathe for a few minutes, then hit all the reset buttons, and see if that brought it all back up....if not the pot likely needs to be replaced. Any looseness in the knob turning, or can you feel the resistance in the pot?

[daryl moses]

Sounds like the speed potentiometer failed on you. It is a small, inexpensive part, and they will replace it. If I were you, I would try to unplug the lathe for a few minutes, then hit all the reset buttons, and see if that brought it all back up....if not the pot likely needs to be replaced. Any looseness in the knob turning, or can you feel the resistance in the pot?
Yep, sounds like the speed pot, it's about a three dollar part but Grizzly will replace it for free. Mine [G0733] started acting up about a month ago. I contacted Grizzly and they promptly sent a new potentiometer no questions asked.

[lynn cranmer]

Sounds like the same problem I had. It was the potentiometer. I got one from Grizzly,but it took them a long time to get it to me,so I ordered three of them from Amazon for $15 for all three. No problem since then.

[Michael Schneider]

If it is a pot I would suggest getting a honeywell rv4n type (milatary grade) http://www.newark.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=15003&langId=-1&urlRequestType=Base&partNumber=01F2644&storeId=10194


PS. If you are not sure, here is a simple way to test http://www.wikihow.com/Test-a-Potentiometer (if you don't have a multimeter, the cheapest one from harbor freight would do the job)

[Bill Boehme]

If it is a pot I would suggest getting a honeywell rv4n type (milatary grade) http://www.newark.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=15003&langId=-1&urlRequestType=Base&partNumber=01F2644&storeId=10194...

I concur. Don't mess with the cheesy pots. This is a component that sees very heavy use and a heavy duty part should be used.

[Mark Greenbaum]

Sounds like the speed potentiometer failed on you. It is a small, inexpensive part, and they will replace it. If I were you, I would try to unplug the lathe for a few minutes, then hit all the reset buttons, and see if that brought it all back up....if not the pot likely needs to be replaced. Any looseness in the knob turning, or can you feel the resistance in the pot?

Just got home from a party for my kids, and the unit was unplugged all day. I plugged it into power, and it's the same as it was before - 0-80 rpm, fine; 81 jumps to 800 rpms, nothing in between. I don't know what you mean by reset buttons, so please let me know what those are. I always turn power on in neutral rotation. The knob was tight on the pot shaft. I checked that earlier.

[Roger Chandler]

Mark, it sounds like the potentiometer needs changing out. The fact that you have the gap with a dramatic increase in rpm's seems to indicate a bad pot. Fairly simple fix.....just follow the good advice given in this and in Lynn and Brice's threads. I would try to get the military grade if it were me just to avoid a possible repeat of the problem.

[Steve Arnold]

It may just be that the contact points have gotten gummed up over time. With the lathe's power off, try spinning the speed control knob back and forth 15 or 20 times and see if that doesn't cure the problem.

[Brice Rogers]

Mark, here are three pictures that may be of a small help to you. At least you'll know what you are getting in to before you take your G0766 lathe apart.

One picture shows the switch and speed control assembly. The other two are close ups of the pot. If you are nimble-fingered, I suppose that you could cut the original wires close to the old pot and resolder them to the new one. The Griz replacement pot came with wire pigtails attached. So I snipped the original wires fairly close to the old pot, stripped them and attached them to the pigtails. I twisted them, then soldered them (Yeah, I know....) and insulated them with the small wire nuts. I may have also taped the three wire nuts together or ti-wrapped them (yes, I know...belt and suspenders,..)
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[Mark Greenbaum]

Brice, again, thank you for the informative pictures. I just got off the phone with Paul at Grizzly CS, and have replacement potentiometer coming my way asap. Also spindle bearings (in case the clicking noise I've heard is the bearings on the way out) and touch-up paint (from delivery scars). Very nice guy to deal with, and helpful. I'm still going to try to find a mil spec pot locally to be the replacement; just need to find time to look for it. Thanks FORUM - you guys rock.

[Dennis Ford]

I can not argue with the logic of using a high quality potentiometer, they get adjusted a LOT but I have been using a Radio Shack pot ($2.99) for at least 7 years on my lathe with no issues.
The pots get a lot of use / mechanical wear but handle very low current.

[Mark Greenbaum]

WOW - fast service. I called about 10 am yesterday and the order has shipped, and should be here today. NICE. I can be turning again very soon.

[Michael Schneider]

Dennis,

That is a very good point about using military grade vs Radio Shack. I had a similar discussion with my neighbor the other day. They have a nice, brand new house full of builder-grade components. Builder grade is the lowest grade that meets code. They do meet code, and most will last the life of her house. Some will fail (a key component that keeps the finished basement dry already has :-( ).

I explained that I made a personal choice to replace items that fail with the best components I can find (as long as price delta is within reason). I spend my time fixing the component, and the failed component can negatively impact something. In their case, the finish basement flooded . I replaced my sump pump last year with a Zoeller pump (cast iron, made in usa). It cost me $30 more then the cheap home depot unit, so it was under the "within reason " price difference. My Zoeller pump could still fail, but the odds are much less.

I choose to spend a couple of $$ more for the best components I can find when I fix something because it gives me:
- piece of mind
- the pleasure of using something that is really good (ex, Zoeller pumps are very quiet, and doesn't wake me up at night), military grade pots are very smooth, etc
- Since i fixed it myself, the cost of labor is out of the equation, so I apply that to delta cost in buying the better component.


The pot on a lathe control is not mission critical, but it will likely fail at midnight, when you are trying to get that batch of items you are taking with you on the Christmas trip.....(you know the drill..) A basic pot may never fail on you, and you can pocket the money and buy a cup of coffee ($8.64 vs $2.99).

Deciding which component to buy is a very personal one. Anything to spec will meet the code. In the past, I have worked for several american manufacturing companies that made top shelf gear. I was taught by the old guys there not to skimp on the small stuff, those are the things that make a difference (ever had a power window switch in your car fail).

There is not a wrong answer here, just personal choices.

Happy turning,
Michael

[Mark Greenbaum]

WELL - Looks as though the replacement cheap Chinese potentiometer from Grizzly has failed again. I've order a Honeywell for $8 off ebay, and I've sent an email to Grizzly CSR with attention to Papa Grizzly. They need to have better simple parts to match the quality of this lathe.

[Brice Rogers]

Hi Mark,

I'm still on my 2nd one but it is "noisy" and I can hear the lathe speed "dither" a little bit at times. I have a replacement but will wait until it gets worse. This time I'm going to add a connector with it so that it will be easier to replace next time. Luckily, they are inexpensive and readily available from multiple sources.

[Mark Greenbaum]

I was able to finish a hollow form of ash, but the fluctuating speed has many drawbacks. I basically have to get a speed that works then switch to no rotation to inspects, then switch back to rotation. Luckily it's a small vessel so not much to worry about off balance start ups. It lets me know just how spoiled I've become having a powerful lathe that works. It should be repaired by next weekend. The Honeywell shipped yesterday and should be here Thursday (free shipping = slow).

[Roger Chandler]

I got two new potentiometers from Grizzly to replace if mine ever goes south. About 3 weeks ago, I felt a slight hiccup a couple of times when I turned the speed up, but after being gone on vacation and coming back, it seems to be normal. I want to hear if the one Mark got from Honeywell is that much better.......if so, I will likely order one as well.
I think I may have been pushing in on the knob, and not just dialing it left or right, which would affect the quality of the contacts inside..........seems fine now, anyway.

[Brice Rogers]

The Grizzly potentiometers (or "pots" as they are known) are 10K wirewound devices. That means that they have very fine wires wrapped around a cylindrical core. There is a metal "wiper" that rubs on the wires. The resistance is determined by where on the length of wire the wiper is touching. I think that there are three failure modes:
1. The wiper stops making contact intermittantly (one my first pot I had areas of drop out: 450, 455, zero, 450 rpms...).
2. The wiper is not making a good contact and/or there is some crud or contamination on the wires (this is the "noisy" pot like on some old radios where the volume control and on-off switch were combined. When you would turn them on they would crackle). This can be temporarily remedied by rotating the knob back and forth.
3. A broken wire. I think that this is the situation where it goes from nothing to a high rpm.

The Honeywell potentiometers appear to have three types and none of them are wire wound. Their website says that they use "precious metals" (gold?) on the wiper contacts (plural). I know that the Griz pots have a single point contact that just looks like some sort of plated metal - - nickel perhaps ?. The Honeywell pots have a good reputation in industrial controls. Hopefully it'll work out well for Mark.

[Mark Greenbaum]

The first pot I had showed as a break in the coil, where it would just quit at about 800 rpm. I think this one (1st replacement) is similar. I wrote to CSR and tried to talk to them Friday, but they said I'd need to talk to Tech Support, and because I am at work, not near the lathe, that might be fruitless. I'll try to call today from work if I get a chance (maybe get a spare pot, in case the Honeywell acts badly). I think I have a nicely turned hollow form for my daughter's 15th birthday on Halloween. Luckily she loves things I make for her (although she hinted she'd like a piece of handmade jewelry, so I will have to make her some glittery object, too).

[John K Jordan]

...(although she hinted she'd like a piece of handmade jewelry, so I will have to make her some glittery object, too).

A friend here made some TINY Christmas ornaments to hang on a tree. I think they would make interesting ear jewelry. I want to try some.

[Mark Greenbaum]

A friend here made some TINY Christmas ornaments to hang on a tree. I think they would make interesting ear jewelry. I want to try some.

Apparently she's seen some steam punk earrings, and wants me to make a pendant with old watch parts. I do have a few old pocket watch parts that I hand engraved, and can set an opal or pink tourmaline into the mix to create a unique heirloom for her. But with one day to design and fabricate, it'll be tight timeframe.

[Mark Greenbaum]

Tech Support at Grizzly has come through for a one time exception to the expired warranty, and has shipped another speed control potentiometer. It should be at my house by the same time the one from Miami (via Venezuela ??) should also arrive. Ebay is so covert - the seller was in Miami, FL, but the part is shipping from Venezuela - I hope I don't get put on some sort of watch list.

[Mark Greenbaum]

Apparently she's seen some steam punk earrings, and wants me to make a pendant with old watch parts. I do have a few old pocket watch parts that I hand engraved, and can set an opal or pink tourmaline into the mix to create a unique heirloom for her. But with one day to design and fabricate, it'll be tight timeframe.

I guess the jewelry idea is not meant to happen right at this moment. I had a fine design idea all laid out and the pieces on my soldering pad, the torch hose after 20 years of having propane in it, decided to give up the ghost. Leaked when I opened the valve. So I shut off the fuel, and found the leak, cut the hose down and re-attached to the barb with the ferrule, and fired it up. Key word is FIRED it up. After I lit the flame the other end by my hand ruptured and caught fire - I blew it out, and then it re-ignited, and I blew it out again. Luckily, I shut off the fuel in time to prevent any damage, other than a first degree burn on my thumb.

45 years of being silversmith/jeweler, and I've never had that occur. I order a whole new assembly this morning, and the jewelry piece will have to wait till next week. Meantime, she got the hollow form I created last weekend, unbeknownst to her. Shs OK with that. Dad made it special.

Sometimes it's tough to be creative on short notice.

[Mark Greenbaum]

I received both of the Potentiometers yesterday, but have not had a chance to install either one. The Honeywell has been through more countries than I ever have been. It's made in Mexico, shipped from Venezuela (agent in Miami), to Panama, to Costa Rica, then to US. All for under $8!! It actually does not turn as smoothly as the Chinese pot from Grizzly. But I'll try the Honeywell first, and hope the Griz will be a never-to-be-used spare. I will install shielded male/female quick disconnects, just in case.

[Robert Willing]

This is frustrating. After waiting a week trying to get a tool rest lever they tell me it was discontinued and were going to send me a replacement. So I never looked up the part #, so I said OK and later find out it is a potentiometer rather than a tool rest release lever. Maybe they were reading this thread? I will call them Monday and try again.

[Brice Rogers]

Yes, I noticed the "N/A" in the priced parts list. If you get one that fits and looks somewhat close, please post the replacement part number.

[Robert Willing]

This is the replacement # P0733096

[Mark Greenbaum]

For the Tool Rest Locking Lever p/n is P0766054, if you mean the threaded bolt and lever that lock the height of the tool rest. For the G0766 the parts diagram is:
https://www.grizzly.com/products/g0766/parts

[Robert Willing]

Here is the tool rest part # I mentioned before. After talking with Technical Support, we have created the warranty replacement order #9032598 to send the replacement P0698013 Tool rest lock lever to you at no charge. Again, we apologize for any inconvenience this may cause.

[Robert Willing]

I took your advice and bought a better one along time ago just to have it on hand. I think Newark was the source.

[Mark Greenbaum]

Here's a couple of picture of the 2nd failed potentiometer. The coil ahs frayed near the middle causing dead shorts. I sure hope the 3rd will behave, but I have the Honeywell in my back pocket as a spare in case.

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[Bill Boehme]

Here's a couple of picture of the 2nd failed potentiometer. The coil ahs frayed near the middle causing dead shorts. I sure hope the 3rd will behave, but I have the Honeywell in my back pocket as a spare in case.

I can't believe that they use wirewound pots which are more appropriately intended for applications where the pot setting is rarely adjusted. As mentioned previously, conductive plastic pots are the only solution that makes sense.

[Mark Greenbaum]

I can't believe that they use wirewound pots which are more appropriately intended for applications where the pot setting is rarely adjusted. As mentioned previously, conductive plastic pots are the only solution that makes sense.
What would a good replacement, that is made in USA, and can handle 1000's of rotations be? I've got the Honeywell as a spare, but is that going to be sufficient? What do Powermatics use? I cannot find a good alternate part number for theirs, and $75 for a control pot seems a bit much $$$.

[Bill Boehme]

What would a good replacement, that is made in USA, and can handle 1000's of rotations be? I've got the Honeywell as a spare, but is that going to be sufficient? What do Powermatics use? I cannot find a good alternate part number for theirs, and $75 for a control pot seems a bit much $$$.

If the Honeywell pot has the right form factor (¼" shaft diameter with threaded mounting bushing that fits the hole size), linear taper, and correct resistance then you should be good to go. Conductive plastic pots have excellent specs WRT wear cycles. It's not necessary to go to MIL-SPEC pots unless you're turning in extreme environments (South Pole, steaming jungle with fungus growing on everything, salt water spray, top of Mount Everest, bottom of Mariana Trench in the Pacific Ocean, Sahara desert sandstorm and 130°, Mississippi delta mud, direct nuclear hit, run over by a tank, etc).

BTW, the pot referenced in post #7 isn't MIL-SPEC, it's commercial grade, but it's perfect for what you want.

[Mark Greenbaum]

What I ordered that took the long way around from SA to CA to USA was this:

RV4NAYSD103A Honeywells Potentiometer 10 Kohm 2Watt (https://rover.ebay.com/rover/0/e11050.m43.l1123/7?euid=b9ecaf438c19458a8fb6b631cda901bc&bu=43185740589&loc=http%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F252981 162551&sojTags=bu=bu)