Thread: 4 jaw chuck problems

Hi Grahame,
I wrote this up on a few other forums for members with problems, so some of it might over lap with what you have already done.To add to it with your problem, the centre on the screw is not always machined true to the screw and it sounds like yours isn't. No worries, just give the yoke a bump down and it will be fine.

I go through and give all my chucks a deep clean every once in a while.

Before starting, grab a piece of paper and draw the chuck with a mark for orientation to make sure they go back where they come from. For reference, I use the machined recess where the makers sticker goes on the front to show which way. Not doing this will become a headache trying to figure out which one goes where, at least on Chinese chucks.

Once the jaws are out, the yoke is on either side of where the unthreaded part of the screw is. Put the chuck face up and a few 1 inch bit of timber around the outside for clearance, then gently use a punch on either side of the yoke to force the pins out (I use a slightly bent flat blade screw driver without a handle). Once they are down so far the screws will come out and you can tap the yokes the rest of the way and you can clean everything up.
I use spray can degreaser with a tooth brush to wash mine out as it's cheap, then compressed air to blow it off dry.

If you have kept them in order, putting them back in is just a matter of lining them up and tapping them back in. I well oil the holes and yokes before putting them in so there is no chance of rust starting.

As I said above, with yours it's just a matter of knocking the yoke down a little so it clears the high spot.

Dave

Thanks Dave,
Great instructions and as a result ,its all back together.
Slick,
can't say thanks enough

Grahame

No problem Grahame, good to hear it's all sorted and your on you way. Nothing worse than having a sticky jaw, especially when reversing them.

One tip for when your reversing the jaws is to use a 1/2 inch socket brace, they can be picked up for near nothing at markets if you don't have one. The 1/2 inch probably wont fit you chuck like mine, so either mill of grind it down to suit your chuck. It doesn't need to be spot on as your not doing the chick up with it, and makes reversing them so much quicker.

I also go through all my chucks from new and remover the burrs etc like you had already done, it makes it feel a lot better.

My lathe is similar to yours and this is an extended D1-4 key I made up to save my knuckles catching the top of the headstock when changing chucks.


I couldn't be bothered setting up the mill that day, so I just filed the square. A heat up and dip in old motor oil gave it a nice black rust resistant finish.



These speed handles make life easier as well, a simple arvo job using the original keys. The Allen head bolt that holds the revolving handle on also clamps it to the T handle. I filed a small flat for it to sit in to stop any twisting.
I just used a piece of S/S tube I had here over the body and pressed a collar on it to keep it there. I put 4 grooves in the 4 jaw one and 3 in the 3 jaw one, it makes it easy to see which one your grabbing and also saves time.





Dave

Thats a coincidence I bought some round bar this week for the express intention of turning some new keys.

One will be and extension but I have also planned for a pair of short keys to use each side of the chuck in the horizontal position to move opposing jaws in and out respectively. The speed handle is a nice touch, I like it.

During the dis assembly I also took the backing plate off as well. For anybody else wanting to pull the backing plate, screw the socket head cap screws out above the chuck surface and whack em with a soft faced hammer. Why? I wanted to see what retained the yoke pins.

The answer is nothing, as they are a press fit. I was amazed at the scratches and dings on the interior surfaces,one on a register surface. a bit of filing sorted those.There was some yellow paint on the recessed cast surfaces and some flight rust which I wire brushed and attacked with my goop.

Thanks for the photos they are a good resource.

Grahame