# G4000 Speed Belt Issue



## wilkerd1 (Oct 25, 2022)

I picked up a used G4000 lathe as my first lathe for learning. The belt that came with it will only install on a couple of different speed pulley combos. Unable to use the belt for the larger slower speed pulleys. Particularly now because I have a steel round I’m trying to turn and the chuck is spinning too fast; not getting a decent finish at all like I have on a couple of aluminum test turns.

Ordered some replacement belts based on the size stated in the manual but they are the same size as the belt that came with it. The belt that came with had no size markings.

Does anyone know if this machine requires 2 different belt sizes? Is there a detail I’m missing to make the state belt size work for all speeds? The Grizzly manual doesn’t reference that 2 belts are required to access all the speeds. 

Thanks!


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## markba633csi (Oct 25, 2022)

I don't own a G4000 myself, but I'm wondering if maybe the problem is with the belt tensioner?
Which of the ranges are you having trouble with?
Here is a screen shot of the factory manual:
-Mark


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## wilkerd1 (Oct 25, 2022)

Thank you for sharing the diagram Mark. That’s a helpful visual aide. 

The belt tensioner seems to work ok. The challenge is the stated belt size won’t stretch and fit for those pulley connections like BC1 and BC2 in the diagram for the slowest speed settings. Seems like the belt is just too small. 

Is there a trick to stretching that belt onto the larger pulleys with out damaging the pulleys and belt (or my fingers lol)?


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## wilkerd1 (Oct 25, 2022)

Figured a pic would help show the issue


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## RJSakowski (Oct 25, 2022)

One belt should be working for you.  Asian belts use a different system for marking belts and it doesn't directly convert to ours.  It seems that the belt's nominal size is always about an inch smaller than the measured size.  I suspect that the P.O. bought a replacement based on the nominal size of the OEM belt listed in the parts list which is a 5 x 710mm belt.  That should convert to a 28 inch belt but measuring the belt would most likely yield a 29" belt.

I  measure belt sizes by placing the 5" mark on a tape measure at a reference mark on the belt and running the tape around the belt to the reference mark, keeping the belt flat as I do so and then subtracting 5" to get the belt o.d.  US marked belts o.d.'s usually measure fairly close to the nominal size.   

I would suggest measuring your existing belt and and buying one a half inch or one inch larger.  I believe that you will want a 3L 290 belt but see what you measure.  Don't get too long a belt or the belt tensioner won't be able to apply proper tension.  The safest way would be to take your belt to a local vendor and have them measure the belt and go one size larger.

Edit: based on the listed part soze, you may need a 2L belt.  A 3L belt is 3/8" wide at the top.  A 2L belt is 1/4" wide.


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## wachuko (Oct 25, 2022)

I thought I was the only one with this issue...   This is what I did... it involves using the tensioner in the opposite direction... 

So in your photo... place the belt over the tensioner and that should give you the added distance needed... the the tensioner is used opposite to what you are used to... 

Sorry... not close to my lathe to take photos... and do not have photos in this computer showing what I mean...


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## markba633csi (Oct 25, 2022)

It looks from your picture that it's practically there- is the tensioner lever at the loose position?
I was also wondering if the belt could go over the tensioner ...?
From your picture (post #4) you are trying to do an illegal combination- on the B pulley the belt should be on the smallest groove to do BC1


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## wachuko (Oct 25, 2022)

Oh... mine came with two belts...  5 x 710mm and 5 x 730mm


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## wachuko (Oct 25, 2022)

markba633csi said:


> It looks from your picture that it's practically there- is the tensioner at the loose position or can you lift the tensioner pulley up while you put the belt on?
> I was wondering if the belt could go over the tensioner also...?


Yup... I missed that...


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## wilkerd1 (Oct 25, 2022)

Thanks for all the help guys! I appreciate it.

Just tried running the belt on the top side of the tensioner and it worked! Been trying to use the pictures in the manual and it seemed like in all of their diagrams the belt always sits underneath the tensioner. Is it a error in their manual perhaps?


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## wachuko (Oct 25, 2022)

wilkerd1 said:


> Thanks for all the help guys! I appreciate it.
> 
> Just tried running the belt on the top side of the tensioner and it worked! Been trying to use the pictures in the manual and it seemed like in all of their diagrams the belt always sits underneath the tensioner. Is it a error in their manual perhaps?
> 
> ...



That is exactly what I went through... I just could not figure it out... Until I solve the mystery, running the tensioner over and under, depending on the speed and pulleys used, has been working fine for me...


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## Bi11Hudson (Oct 25, 2022)

With the immediate need resolved, my comments will be "in retrospect". Not useless, but not very timely. . .

I have a Grizzly G-1550, essentially the same as the G-4000, just a predecessor from a different manufacturer. My drive belt is a *Gates 5M720*, meaning 5 mm wide by 720 mm length. The G-4000 _may or may not _use the same belt. I have a source a couple of miles away that sells the Gates belts. They are a surprisingly strong 60 degree belt that should not really be run by the inside surface. I have used them for several projects because the sheave is simply a threading tool.

*Wachuko*, the following might be of interest to you as well.

The motor drives a "secondary" pulley that contains an internal torque limiting clutch. The outer sheave, the smallest, will give ~135RPM, the slowest the machine is capable of. It is for this reason I built a reduction gear from automotive parts to get a 3:1 gear set. I will include the description. It doesn't cost much but is time consuming and requires some (lots of!) patience. But for my work, getting that reduction was worth the effort. The parts were cheap (free) because I was looking for scrap parts, not too specific.

The limiting clutch is just a spring loaded ball running against a back plate. During a heavy cut, a "clicking" may be heard. That is the ball shifting. It *will* require correction eventually. Usually just stretching the spring will suffice. There is(was?) an aftermarket device replacing the clutch that gave some reduction. I don't believe it got dowm to what mine will (~45RPM) but *is* a "bolt on" part. I don't know where to find one, I just saw a reference to it a long time back. But doing a search for 9 X 20 machines should hit on it eventually.

.


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## wachuko (Oct 26, 2022)

Bi11Hudson said:


> With the immediate need resolved, my comments will be "in retrospect". Not useless, but not very timely. . .
> 
> I have a Grizzly G-1550, essentially the same as the G-4000, just a predecessor from a different manufacturer. My drive belt is a *Gates 5M720*, meaning 5 mm wide by 720 mm length. The G-4000 _may or may not _use the same belt. I have a source a couple of miles away that sells the Gates belts. They are a surprisingly strong 60 degree belt that should not really be run by the inside surface. I have used them for several projects because the sheave is simply a threading tool.
> 
> ...


Thank you for sharing the document.  It continues to amaze me the amount of knowledge shared in this forum and the willingness of the members to help those that are starting this journey…

So much to learn…so much to learn…

That is one heck of a project for this newbie (me, not the OP).   Just figuring out what car that came from would be a great task in itself  

I saved the document for reading a few more times to better understand it all that is involved in making this.

But I have to ask… and the document is not dated to know how recent this was made…did you ever fix the 14” junker lathe referenced in the document? 

Oh and lots of words of wisdom- “A smooth chamfer here may well save a finger one day.” 

Thank you again for sharing


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## Bi11Hudson (Oct 26, 2022)

Thank you, Sir, for the upvote of confidence. The article was written long ago, before the G-4000 was available. Twenty some years, I think. For what its' worth, I recieved a letter from the Irish Trade School commission asking permission for them to use my article in their training. Of course. it was given. The gears were from a Chevrolet 3 speed(?) automatic. I don't know what model, the shop had a machine shop in the back and the parts were laying on a shelf. The owner mentioned the trans model but it didn't mean anything to me. I got lucky on the bushing, happened to be scrounging at an aircraft parts reseller and stumbled over it.

The "junker" was eventually passed on, given to a blacksmith in exchange for some work that never got done. (I had a serious stroke) I got stuck in a chair and many things got interrupted. It was in sorta usable shape. Usable to the blacksmith, but not for any serious precision work. Such as the cross slide dovetails were so worn that one could see the curve in them.

I am an electrician and electronic repairman by profession. See the "sea story" on MrWhoopie's "Horror" page. I do *some* machine work as part of my hobby of building models. But not enough to call myself an expert. In essence, the article was written by a novice for other novices. That's why some things are "sort of" accurate. Not much planning, I knew what I needed and just built it as I went along. The point being is that a novice *can* build it, with a lot of patience.

As far as the "words of wisdom", I have many, *many* scars from working with my hands. Some from not thinking about what I was doing, some from pure happenstance in my job. I figure if somebody else can avoid some of my mistakes, there may be less blood shed. Since the series of machines (9X20, et al) is so wide spread, I figured others would have the same needs.

.


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## chip maker (Oct 26, 2022)

I have owned my G4000 since new in 2000 and thru the years have had issue with the belts. So awhile back had nothing to do so checked this out again as I was using two belts for different setups. Finally found a good article and found that the biggest issue is there is really an adjustment issue with the motor adjustment and the first drive pully adjustment. The motor cog belt can be adjusted by the motor and by the cogged belt drive pully. The trick is to be sure to use the belts that your machine was designed for, and it doesn't take much of a change between these two adjustment points so it's a time game to get them set to where the pully belt will work on all the pullys without using different belts. Believe me it takes alot of fouling around to get it just right, but it can be done. Also, there is two cog belts for this machine depending on when it was built. Without having the correct cog belt can cause problem with the pully belt sizing as there is only two of those listed.  All this depends on date of manufacture. Good luck !!!


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