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Threaded chuck vs chuck with back plate?

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Aaron_W

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#1
Looking at chucks I see there are basically two common mounting methods.

1. Solid chuck that has the mounting method (threads, camlock etc) as an integral part of the chuck.

2. Separate chuck that uses a fitted removable back plate.


Are there any functional performance advantages to either method?

A backing plate obviously makes things easier for the manufacturer / seller of chucks since they don't have to make and stock as large a range of options, just chucks and a variety of backing plate.
This advantage would of course also apply to the buyer of used chucks, as they can buy a chuck that has the wrong back plate for their lathe and make or buy the correct back plate which is generally considerably less expensive than a good quality chuck.
 

JimDawson

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#2
The plain back chuck (removable backplate) is always preferable. That way you can machine the backplate on your machine to fit chuck of your choice, and the backplate will be concentric to your spindle.
 

benmychree

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#3
On the other hand, on smaller lathes with shorter bed lengths, a chuck with integral threads gives a longer center to center (usable) distance, possibly by as much as a couple of inches.
 

Cadillac

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#4
I can see a integrated one being stronger or more ridged. Getting picky but weight is closer to bearings.
 

benmychree

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The weight issue is minor compared with cutting forces, and the longer the distance from the face of the spindly, the greater they are, both by weight and cutting force.
 

mikey

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#6
The advantage to an integral camlock chuck is that they are supposed to be made to a DIN standard with a 7 degree, 7 minute, 30 second register angle. Done well, this improves and standardizes fit and accuracy. It also minimizes overhang to reduce spindle static load.

Backplates fit the same standard but the accuracy with which the chuck fits the backplate varies with the user.
 

Aaron_W

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Thank you, that all makes sense.

Most of the integral thread chucks I've seen are smaller chucks, often marketed to specific smaller lathes. The larger chucks usually have a back plate and are not marketed for a specific machine. The more compact nature of integral threads makes sense for the small machines, the larger chucks going on machines less concerned about saving an inch of center length.
 

P. Waller

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#8
Ease of chuck changes makes camlock, L taper and American Standard tapers very useful, I sometimes change chucks 3 times in a single 8 hour day. Camlock makes this simple even on a 24"+ swing machine, A taper spindles are a bit more work yet faster then a large threaded spindle. No machine builder has made a threaded spindle machine in the last 50 years or so.
 

Aaron_W

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Ease of chuck changes makes camlock, L taper and American Standard tapers very useful, I sometimes change chucks 3 times in a single 8 hour day. Camlock makes this simple even on a 24"+ swing machine, A taper spindles are a bit more work yet faster then a large threaded spindle. No machine builder has made a threaded spindle machine in the last 50 years or so.
That makes sense in a production setting. I've probably removed my chuck 3 times in the past year. :)

Some of the smaller (10" >) lathes still have threaded spindles.
 

P. Waller

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#10
That makes sense in a production setting. I've probably removed my chuck 3 times in the past year. :)

Some of the smaller (10" >) lathes still have threaded spindles.
Until the 1920's or so Hardinge made Hardinge/Cataract lathes that were threaded/taper spindles, mostly on chuker lathes, this appears to drive people batty when they have one as a hobbyist, why a hobbyist would buy a chucker I do not know.
 
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