G4000 Speed Belt Issue

[wilkerd1]

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]

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

 

[wilkerd1]

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]

Figured a pic would help show the issue


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[RJSakowski]

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.

 

[wachuko]

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...

 

[markba633csi]

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

 

[wachuko]

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

 

[wachuko]

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...

 

[wilkerd1]

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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