G0766 lathe toolrest vibration

I posted this in the Green Monster G0766 group but it was too long and it wasn't accepted. So I'll throw it up here for any G0766 folks.

I've owned a new G0766 for about 6 months and I use it nearly every day. I think it's a great lathe. From the git-go, I occasionally have a very fine, but severe vibration, for lack of a better way of putting it, when I'm hollowing the center of a bowl. It doesn't happen consistently but it happens enough to concern me. After a period of weeks of turning, i look down and the lathe has walked a couple of inches. The source of the vibration confused me because i couldn't pinpoint it. I thought it might be the head stock or unlevel ways. The lathe is dead level and I was never convinced the headstock was the cause of the vibration.

Anyway, I know this has been discussed before but I was looking for a inside bowl rest and most of them are too short to fit this lathe and banjo. I had an email conversation with robo hippy and he mentioned to me that because of the shorter design of the banjo, the tool rest needed to be longer. He had a concern that because of the longer tool rest, there could be vibration issues, especially when working near the end of the rest. As I was turning yesterday, the vibration developed and I really believe the source of it is at the tool rest. The vibration seemed to disappear or significantly lessen when I was working directly over the post.

Has anyone else had an issue such as this? It makes sense to be because rather than having a taller banjo and a shorter tool rest, we have just the opposite on the standard banjo that comes with this lathe. I'm considering buying a different tool rest.

First off, the GGMG or any group will only allow for a post of 1000 characters of type, so we usually divide longer posts into smaller posts, and perhaps put continued on next post on the end of the first one.

I have had the G0766 probably longer than anyone on the forums here and elsewhere, and the banjo neck was shortened by about 3/8" on the larger/heavier revised banjo that Grizzly engineers had made for the G0766. Your lathe came with that larger banjo. I have never had an issue with tool rest vibration. I do mostly use Robust rests with my G0766, and the total height of the rest from the tool bar where the gouge rides to the bottom of the post is 8-3/4" inclusive.

I've turned some very large and heavy wood on the G0766, and do not believe that vibration in the toolrest is an issue, unless perhaps, one is out on the very end of the rest. If one does that cut way out on the end, they need to be careful not to get a catch, because with a cast iron rest, like the stock rest is, that catch can cause the post to snap in two! I had it happen on my former G0698 18/47 lathe, and on my first Craftsman 15" lathe that had cast iron rests.

That is one of the reasons I went to aftermarket rests. Robust will make you custom rests with total height of 8-3/4" if you want, and you can get them in 25mm post size if you want, but I prefer to enlarge the hole to 1" with a twist drill bit and some oil to lube the cut, and make it where all 1" aftermarket accessories can be used. Your unit, being 6 months old may have come with the 1" hole in the banjo as someone reported they modified the specs to allow for that.....I do not know for sure personally.

I wonder if you could bolt a heavy chunk of lead to it somewhere to
work like a harmonic balancer ?

You probably already checked this but make sure the banjo is clamped to the ways good. Looseness can cause vibration or chatter. Dry wood can also cause chatter but again you are probably aware of this.

I just bought this lathe. I want to point out that the newest ones, like mine, have a 1" post, not the 25 mm post. I purchased the Best Wood Tools Modular rest system with 3 bars and an 8" post (powermatic post). I haven't turned much with it nor the OEM rest, but thus far haven't noticed any vibration unless my tool is way out over the rest. To rule out your rest, I suggest trying a different one. If it only happens when cutting and you don't have any play in your drive stock, it could very well be the rest.

I do not know if this will help but try using a bolt in one of the extra bolt holes on the banjo neck to see if it helps, whereas you will have two tensioning positions on the rest post . I ordered one extra from grizz. they are cheap I keep them at 90 degrees for two directions of tension on rest post . seems to grip post better to me, less slop less vibration.

Quote:

---

Originally Posted by tom lucas

I just bought this lathe. I want to point out that the newest ones, like mine, have a 1" post, not the 25 mm post. I purchased the Best Wood Tools Modular rest system with 3 bars and an 8" post (powermatic post). I haven't turned much with it nor the OEM rest, but thus far haven't noticed any vibration unless my tool is way out over the rest. To rule out your rest, I suggest trying a different one. If it only happens when cutting and you don't have any play in your drive stock, it could very well be the rest.

---

My fundamental issue is with the height of the 'riser' part of the banjo. It doesn't 'rise' very much, hence the tool rest post has to be longer. I think I will purchase a one way or similar banjo. I'm not real keen on having to spend the $200 but I just believe the stock grizzly banjo is not what it could be if it was designed correctly. Sorry, I can't get the picture to orient correctly.

Looking at Randy's picture, if you have a metal collar under the thick part of that post, it would provide better support for the tool rest, and have you at center height every time. You may need a couple of collars for slightly higher or lower...

robo hippy

Quote:

---

Originally Posted by Randy Hogan

My fundamental issue is with the height of the 'riser' part of the banjo. It doesn't 'rise' very much, hence the tool rest post has to be longer. I think I will purchase a one way or similar banjo. I'm not real keen on having to spend the $200 but I just believe the stock grizzly banjo is not what it could be if it was designed correctly. Sorry, I can't get the picture to orient correctly.

---

Randy, I think your assessment of this is faulty, and I don't mean that as a criticism at all, I'm just trying to help with the following information. I have a Oneway banjo that I got when the G0766 first was introduced with the smaller banjo. Of course, Shiraz Balolia, owner of Grizzly took it upon himself to have the larger banjo made, and that solved the issue. At the price point of the G0766, not every desire that any turner could possibly have related to features cannot be accommodated.

Now, since I have experience in both a Oneway banjo on the G0766 and the larger banjo Grizzly had made, the best way to go about this in my opinion is to get Robust rests made for your lathe. I ordered "custom rests" from Robust, and they are almost the same in price as their standard offer "long posts" but what you need to have plenty of post into that banjo that came with your lathe is at least 8-3/4" total length from the top of the rail where the gouge rides to the bottom of the post. Even a 9" rest [ total height] will be good if you want more post into your banjo neck, but 8.75" will do the job just fine.

What Grizzly did was make the banjo, and since they had the toolrest design already in production, they just adjusted the banjo neck to make it all work out so as to control the cost of remanufacture and make everything they offered on the lathe work correctly to meet the swing requirements.

Knowing what I know now, if I could do it all over, I would have not ordered the banjo from Oneway, as it really is unnecessary, and would do what I did with the Robust rests, which I wanted anyway, and have six of them in different configurations, all with the 8-3/4" total height to use with my G0766. One great thing was that when I got my latest G0800 lathe, which has a 24" swing, the robust rests match the total height of the G0800 rest that came with it. It has worked out perfectly, as I can use with either of my lathes.

That banjo vibration thing .......I'm not buying it. Some want to say it is an issue, but I've had the G0766 longer than anyone who posts on these forums, and I've turned some very large and heavy wood on it, and for 3+ years have not had any issue at all. I know for sure that the 1" posts on the Robust rests will handle anything that the G0766 lathe will handle, and truly believe that an investment on a couple of those rests with the 8.75" total height will serve you well, and can be had for less than the price of the Oneway banjo. Even a 9" total height will give you more post in the banjo for an even more solid hold, and of course if you want you can add another handle or bolt for the other holes on the banjo to give you even more lockdown leverage. I really do think you would be better served to treat yourself to the Robust rests, than a new banjo. If I thought at all that the banjo that comes with your G0766 was faulty, I would certainly say so, but it is a solid unit, and I believe you need a better approach to your situation with the new rests.

I say these things to try to help you maximize your opportunity here and give you what I believe is the best route to take. I wish you all the best, and hope you will take a serious look. I don't believe the banjo is your issue at all! :)

Roger, would a 9" rest cause problems when you want the rest low? And secondly, is the one-way rest really that much taller than the Grizzly?

Quote:

---

Originally Posted by tom lucas

Roger, would a 9" rest cause problems when you want the rest low? And secondly, is the one-way rest really that much taller than the Grizzly?

---

Tom, the difference in the neck of the banjo that came with your G0766 and the Oneway banjo, is that the Oneway banjo is 1" taller in the neck than the Grizzly banjo.
The hole depth in the Grizzly banjo from its top down to the bar that locks it down is 3-1/4" deep, which would give one a fairly good amount of height adjustment I think. The 1/4" added to my 8-3/4" total height would probably not make much difference, but I have had good success with lower positions with my 8.75" total height and plenty of post in the hole to make it stable. Not once have I ever had a problem with stability of the tool rest with the 8.75" total height. Hope this helps!

Quote:

---

Originally Posted by Roger Chandler

I say these things to try to help you maximize your opportunity here and give you what I believe is the best route to take. I wish you all the best, and hope you will take a serious look. I don't believe the banjo is your issue at all! :)

---

I appreciate the feedback for sure. I'm just trying to troubleshoot my occasional issue the best I can. I will certainly consider the longer Robust rest.

Quote:

---

Originally Posted by Reed Gray

Looking at Randy's picture, if you have a metal collar under the thick part of that post, it would provide better support for the tool rest, and have you at center height every time. You may need a couple of collars for slightly higher or lower...

robo hippy

---

Thanks for the feedback. So if I'm understanding correctly, for that to work effectively, the thick part of the post would need to sit directly on top of the collar.

It's not that Grizzly made the banjo wrong or bad. It's that it's designed for a cast rest. If you look at the costs rests in general the 1" post is shorter in length because the upper portion is taller. The two have to work together. Like Roger said you can get a higher quality welded rest with a longer post which will work just fine with the G0766 banjo. There's other benefits to going with a nicer rest. The cast rests aren't as smooth and nick easier. This makes sliding tools along it harder to do at a consistent pace. The G0766 is a great lathe for the money but it's not an American Beauty. But you now have the opportunity to customize the G0766 to make it even better for your use.