How To Do It?

M

mgbbob

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I have a 1/2" aluminum disc 2 5/8" in diameter. I have drilled a 3/4" center hole. Making a piece for an old wood jointer. I would like to face the disc down to 7/16" but I don't know how to best hold it in the lathe on my 7" x 10". I used a 3/8" bolt to turn the diameter down but that ruined the bolt and I had to but it off. Any ideas?
 
Use either a 4 Jaw or 3 Jaw chuck to hold the disk. You have to be sure that you are not deeper in the jaws then the finished thickness of the disk.
Pierre
 
I'd make an expanding collet out of aluminum or brass to hold the disk on an arbor and hold it in the chuck with reversed jaws for backing. Making the expanding collet out of a soft metal will allow you to run the tool past the center hole and into the collet a bit. cutting into the collet a bit as your facing the part won't hurt anything. But I'm no expert on such things.
 
Would you have a short length of 3/4" bolt that you could mount between the chuck and the tail piece? You could mount your disk between 2 nuts on the bolt, to hold it while you faced down the outer part of the disk. Then with the outer part faced to 7/16" , mount it in your chuck and face down the inner part of the disk. That way you won't have to get too close to the chuck jaws. An alternative way would be to chuck up a 3/4" bolt and mount the disk on it, not using the tail piece, while you face down the outer part of the disk and then remount it in the chuck and face down the inner part.
Good luck on it.
NodakGary
 
I'd friction drive it. Put some tape on the front side of your chuck jaws, open them up to the dia. of the disk then use the tailstock to hold it in place. (putting light pressure towards the chuck to "pinch" the disk) Use a live center, and it should self center automatically if your centers are aligned.

Here is a video showing that:

Even though Tom doesn't use a live center in the video, it might really help for heavy facing.

I've done this method many times in woodturning, works great!
 
If your just facing why can't it be held in the chuck? if it sits to deep put paralells between the chuck and the part to hold the piece out while you tighten the chuck. just be sure to remove the paralells before you start the lathe.
Mark
 
I have an adjustable spider that I use in my 4 jaw chuck so that I can grip thin discs with the face parallel to the back of the chuck.

David
 
mgbbob said:
I have a 1/2" aluminum disc 2 5/8" in diameter. I have drilled a 3/4" center hole. Making a piece for an old wood jointer. I would like to face the disc down to 7/16" but I don't know how to best hold it in the lathe on my 7" x 10". I used a 3/8" bolt to turn the diameter down but that ruined the bolt and I had to but it off. Any ideas?
Click to expand...
Chuck it up and have at it. 7/16" on a 2 5/8" dia is plenty of meat to grip. Use (matched) shims to protect the finished o.d. from the chuck jaws. Use spacers if necessary to make the face proud of the jaws by more than the amount you intend to remove. Bits of aluminum angle work well for this: they can serve both as spacers and shims (you just cut them along with the face).
 
Make sure any spacer that you use, (you might not need any) will not be flung out and hit you or anything else in the area!
Pierre
 
mgbbob said:
I have a 1/2" aluminum disc 2 5/8" in diameter. I have drilled a 3/4" center hole. Making a piece for an old wood jointer. I would like to face the disc down to 7/16" but I don't know how to best hold it in the lathe on my 7" x 10". I used a 3/8" bolt to turn the diameter down but that ruined the bolt and I had to but it off. Any ideas?
Click to expand...

I thought I would give an update. I purchased a 3" x 3/4" bolt. Cut the head off and chucked it in. I center drilled and then double nutted the threaded portion. I turned the back side of one nut down from about 1/2 way across the face to within about 1/8" of the threads. I put the disc over the threads and double nutted proir to chucking into the lathe. I then faced the disc as far down as possible to the right diameter. i removed the item and finished the center area with a file. Seemed to work pretty good for an amature.

Thanks,
Bob
 
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