Regrinding of my 3 jaw chuck jaws

[Ulma Doctor]

i recently reground my 3 jaw chuck jaws with a dremmel mounted on the lantern tool post. i posted the video to Youtube

http://youtu.be/pZ1ebBwRYN4
[video=youtube_share;pZ1ebBwRYN4]http://youtu.be/pZ1ebBwRYN4[/video]

thanks for watching!
mike

 

[coronetracer]

I hope it worked out ok for you , I just today redid one of my chucks . I chucked on the inside of a bearing race to hold the jaws in a rigid state and then bored the jaws . My 2 cents. Happy Machining !

 

[RWL]

The setup is basically ok, but you probably should have had something to keep the jaws under tension when you were grinding them. I did one many years ago without having the jaws sprung outward in tension and I wound up taking too much off trying to get them more even. The chuck works ok, but it no longer holds small diameter items like it used to.

The best idea I've read about for a jaw fixture is a plate with three holes drilled where the jaws would be if they were holding a piece of stock, maybe 1.5" in diameter. The jaws just fit through the holes. The center of the plate is bored out so that the large central hole breaks a little way through each of the small holes. That allows the jaws to protrude a just little into the large central hole. The angled sides of the jaw faces bear on the edges of the holes, keeping the jaws under a little tension when they're being ground.

 

[Daver]

The setup is basically ok, but you probably should have had something to keep the jaws under tension when you were grinding them. I did one many years ago without having the jaws sprung outward in tension and I wound up taking too much off trying to get them more even. The chuck works ok, but it no longer holds small diameter items like it used to.

The best idea I've read about for a jaw fixture is a plate with three holes drilled where the jaws would be if they were holding a piece of stock, maybe 1.5" in diameter. The jaws just fit through the holes. The center of the plate is bored out so that the large central hole breaks a little way through each of the small holes. That allows the jaws to protrude a just little into the large central hole. The angled sides of the jaw faces bear on the edges of the holes, keeping the jaws under a little tension when they're being ground.

I get the concept here, but wouldn't that have the jaws under tension in an inward direction? (you are turning them out as if holding the inside edge of a tube right?) If you are grinding/boring the inside of the jaws wouldn't you want them being stressed outward, so they are pressed against the inside of the thread of the spiral. Your method also assumes that the jaws are all identical and completely symmetrical, right?

I don't have a better answer other then to maybe have teh jaws as far out as you can and still reach all three for grinding/boring... and spin the head as fast as you can and let centripetal force work for you.

 

[Ulma Doctor]

The setup is basically ok, but you probably should have had something to keep the jaws under tension when you were grinding them. I did one many years ago without having the jaws sprung outward in tension and I wound up taking too much off trying to get them more even. The chuck works ok, but it no longer holds small diameter items like it used to.

The best idea I've read about for a jaw fixture is a plate with three holes drilled where the jaws would be if they were holding a piece of stock, maybe 1.5" in diameter. The jaws just fit through the holes. The center of the plate is bored out so that the large central hole breaks a little way through each of the small holes. That allows the jaws to protrude a just little into the large central hole. The angled sides of the jaw faces bear on the edges of the holes, keeping the jaws under a little tension when they're being ground.

thanks for your reply),
you could not see in the video, but i had a piece of 3/4" derlin rod behind the jaws, clamped on a slight step on the back side of the jaws. i used a sharpie to mark the jaws between grinds to see that material was taken off equally!
mike

 

[Ulma Doctor]

I hope it worked out ok for you , I just today redid one of my chucks . I chucked on the inside of a bearing race to hold the jaws in a rigid state and then bored the jaws . My 2 cents. Happy Machining !

thank you, i had a derlin rod chucked at the rear of the jaws,
the set up did bring the chuck jaws back to within .004" tir on drill rod, i'm gonna have to live with it, i don't want to remove to much so i can still grab smaller stuff!)
mike

 

[coronetracer]

Super ! Sounds like you did well and thought out your plan of attack . Happy machining . Ebert