Chuck Weight?

ShagDog

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I have a lathe that I bought used with an 8" swing and a 1 1/2-8 spindle. The chucks that came with it are 5"(3 jaw) and 6" (4 jaw). They are older chuck that are in the range of about 7 lbs and 9 lbs apiece. I purchased a new chinese 5" with a backplate I fit to it. The chuck is very nice in quality; but, it extends out from the spindle much further than the other 2 chucks which have a thin profile. This one has a very thick profile. The new chuck with backplate weights around 12lbs or more (Can't be sure on weight as my scale stops at almost 12lbs). I did try the chuck, and I must say it works very nicely.

Question: Is the new chuck weight going to do any damage to my spindle, bearings or anything else due to the weight?
 

Mitch Alsup

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Question: Is the new chuck weight going to do any damage to my spindle, bearings or anything else due to the weight?

Cutting forces are on the order of thousands of pounds while the differential weight is on the order of 5 pounds.
You do the math.
 

Tozguy

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I would not worry about the extra weight of the chuck simply because of the weight capacity the lathe to hold and turn. Steel is heavy and the extra weight from the chuck is equivalent to a rather small work piece.
 

ShagDog

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Thank's for the responses so far. I did figure out how to weigh the chuck on my limited scale capacity. Should have thought of this to begin with. I took it apart, and to the extent the scale is somewhat accurate, the backplate weighs around 4 lbs, while the chuck weighs around 9lbs., for a total of around 13 lbs.. I guess I was pretty close.
 

ShagDog

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Related question. What is the heaviest unsupported (no tail stock support) material that can be turned on a lathe the size of mine, 8x, with 1 1/2- 8 spindle with tapered roller bearings.

Also, what is the formula for determining cutting force?
 

macardoso

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Related question. What is the heaviest unsupported (no tail stock support) material that can be turned on a lathe the size of mine, 8x, with 1 1/2- 8 spindle with tapered roller bearings.

Also, what is the formula for determining cutting force?

You'll find rigidity to be the limiting factor on unsupported workpieces rather than maximum weight of the work. I usually say if I am 3:1 or greater on the length to diameter ratio, get a tailstock involved.
 

ShagDog

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You'll find rigidity to be the limiting factor on unsupported workpieces rather than maximum weight of the work. I usually say if I am 3:1 or greater on the length to diameter ratio, get a tailstock involved.

I do understand what you are saying; however, I referred to "unsupported" only to be better able to allow me to understand better the weight bearing capacity of the just the spindle on this lathe.
 

Papa Charlie

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I wouldn't worry too much about weight bearing. There is, however, a distinct advantage to the additional weight in my mind, in that it will help absorb vibrations and should help to provide a better cut.
 
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