# Machining a back plate for a chuck...



## jduncan (Jan 3, 2013)

I bought a backplate blank from Tools4less and it mentioned machining a tight fitting plug to fit inside the chuck.  What is the point of this if the backplate is already threaded and I'm just going to face the plate to fit tightly inside the chuck back?

This is the one I bought:

http://www.tools4cheap.net/proddetail.php?prod=225back


----------



## Ray C (Jan 3, 2013)

The screw-on types are pretty easy to deal with.

Clean/wipe surfaces and screw onto spindle. Face the front. Look at the back of the chuck and check to see how much room you have for a shoulder. Cut a small shoulder on the face of the back the same diameter as the ID of the chuck back.

Before you drill holes and bolt it together, do a quick static balance check of the back alone. Find the heavy side and mark it. Mount a rod through the chuck and do the same thing -mark the heavy side. Put the back and chuck together with heavy sides *opposite *and to hopefully end-up with something that's closer to being balanced. Now drill/tap the holes.

When you run a new chuck, close the jaws and test the speeds from low to high. An unbalanced chuck can be unnerving...

How I go about fine-tuning a chuck depends on if it's a collet, universal or independent chuck...

Ray

EDIT:  Fixed a word that confused a sentence.


----------



## swatson144 (Jan 3, 2013)

jduncan said:


> I bought a backplate blank from Tools4less and it mentioned machining a tight fitting plug to fit inside the chuck.  What is the point of this if the backplate is already threaded and I'm just going to face the plate to fit tightly inside the chuck back?
> 
> This is the one I bought:
> 
> http://www.tools4cheap.net/proddetail.php?prod=225back



I make a plug for each threaded spindle. Then again usually I make the backplate from a blank and thread it. In the your case there is probably no need but it is always nice to have.



I haven't made a nose protector/female plug for the little lathe as it is unlikely to ever see a collet.

Steve


----------



## jduncan (Jan 3, 2013)

Ok, so the plug is to test the threads if you have to cut threads on the plate?

I see the point about balance.  This chuck is actually for a 14 or 16 inch lathe so it weighs some 50 pounds.

Thanks guys!


----------



## Hawkeye (Jan 3, 2013)

When I read the description of the backing plate, I took 'plug' to mean the boss you have to turn for a tight fit into the recess in the back of the chuck. The closer the fit, the better your chuck _should_ run.


----------

