Question about 5" chuck on Grizzly G8688 Mini Lathe

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Jon K

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Thinking about going to a 5" chuck for the higher capacity both in the jaws/holding as well as the through-chuck. I know it won't open the spindle, but the chuck is nice to be able to pass slightly over an inch through.

Anyway - with a 5" chuck, 4" stock, can I even turn that down? I don't know that the cross feed can move that far out of the way. Thoughts?
 
You should think about the machine design and putting on a bigger chuck and shaft will it put a strain on the spindle bearings. I have turned parts like that a few times on a Leblond, but that machine has a HD spindle. The way I did it was I used a boring bar that you normally bore ID holes. Set it up on he OD and moved the cutter to the opposite side of the bar. Need to take light cuts and be careful.
 
I'd bet if you are holding a 4" round, the jaws will stick out and hit the bed.
 
AR1911 said:
If the chuck you are looking at is very similar, then go for it.
The spindle can handle it.
Click to expand...

I am just curious as to how I could do any turning on a 4" stock. If I set the tool super shallow and at an angle I almost can't see 4" fitting with the cross feed all the way out.
 
truly, you need a bigger lathe if you regularly exceed 3" material.

If the mini has to do it, then I'd look at a custom toolpost mounting block in place of the compound.

Another issue you may find is that the lowest speed on the lathe may not have enough torque.
If you run it too fast your work quality suffers.
If you are doing aluminum rounds, you should be OK.
 
Regardless of the chuck size the jaws will only open till they hit the bed.The outside diameter of the combined chuck jaws will be the same on the same lathe. You probably might even lose on stock size because the jaws on the larger chuck have more mass. Then there is the question if the small lathe will have difficulty turning the extra weight.

I'm afraid you have come to the inevitable crossroad question, "is it time for a larger lathe?" I wish you well with the answer.

"Billy G" :thinking:
 
Bill Gruby said:
Regardless of the chuck size the jaws will only open till they hit the bed.The outside diameter of the combined chuck jaws will be the same on the same lathe. You probably might even lose on stock size because the jaws on the larger chuck have more mass. Then there is the question if the small lathe will have difficulty turning the extra weight.

I'm afraid you have come to the inevitable crossroad question, "is it time for a larger lathe?" I wish you well with the answer.

"Billy G" :thinking:
Click to expand...

I don't really need to turn 4" stock, I am only questioning the ability to. I really like the 1.18" through chuck size. I rarely turn anything over 2", but the problem is I tend to want to turn longer pieces than fit through the chuck on the stock chuck. I think the 5" is useful for me, I just was thinking about the geometry and trying to think of how the tool post would clear something 4" diameter.
 
Jon K said:
I don't really need to turn 4" stock, I am only questioning the ability to. I really like the 1.18" through chuck size. I rarely turn anything over 2", but the problem is I tend to want to turn longer pieces than fit through the chuck on the stock chuck. I think the 5" is useful for me, I just was thinking about the geometry and trying to think of how the tool post would clear something 4" diameter.
Click to expand...


for you to take advantage of the 1+ through hole that means you'd have to position the chucks jaws in a reverse order as the image you posted shows. that also means that the jaws will extend +1" out of the chuck making the actual chuck diameter +6" which might not fit in your lathe's work envelope (+7" for holding a 2" rod).
 
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