Shop Made Axa Toolpost Cross Drilling Fixture

[JPMacG]

Thanks Mike. I need one of these myself!

Are the bearings pressed onto the shaft? Or is the shaft a slip fit into the bearing inner races and you drill by pushing on the drill?

 

[Ulma Doctor]

Thanks Mike. I need one of these myself!
Are the bearings pressed onto the shaft? Or is the shaft a slip fit into the bearing inner races and you drill by pushing on the drill?

Hi JPMacG,
Yes Sir, the bearings are a light press fit- .001" interference to the shaft
i froze the shaft and slightly warmed the bearings with a heat gun- approx 100*F and pushed them together by hand
after temperature equalization the bearings are effectively, press fit.
the clamp bushing is responsible for holding the assembly for use

 

[Ben Nevis]

I mounted a 5C spin index to the lathe spindle to index with the lathe. I also mounted a die grinder on the cross slide.
Sorry for the poor quality photos, they were taken about 30 yrs ago with a polaroid 600 camera.

 

[JPMacG]

For the toolpost fixture I found a little 1/4 inch capacity chuck in my collection of junk. It looks to be high quality and has no sign of damage. It mounts with a 3/8-24 thread. It is branded "Chicago" and is US made.

I cut a 3/8-24 thread on the end of a piece of 3/8" round stock and, with the stock still on my lathe, I mounted the chuck. I was surprised to find that the chuck wobbles badly. So I cut another thread, this time making it a snug fit to the threads of the chuck. It still wobbles badly.

So my question is, how are these types of chucks kept true? I see photos that show chuck mandrels with a flat below the threaded stud and it appears that the chuck is supposed to seat against the flat. Should I use larger stock and provide a similar flat on my part?

 

[Randall Marx]

Yes, Jon, I would think one should have a threaded shank with a shoulder for the chuck to seat against. Also, see if there is a recess in the chuck that would go over an unthreaded portion of the mounting shank, that could seat on a register between the threads and the shoulder. I'm thinking of something like the register on a threaded lathe spindle nose.
Another thought is this: does the chuck body wobble or is it a test bar (like a dowel pin) that wobbles when chucked? Might pay to check with a dowel pin or drill bit if you haven't yet. If a drill bit runs true but the chuck body wobbles, I wouldn't worry about it.
Either way, please let us know what you come up with.
-Randall

 

[JPMacG]

Thanks Randall. Yes, that was it. I made another part out of 5/8" round stock with a flat for the chuck to seat on. The flat made a huge difference. The wobble is gone.

 

[Randall Marx]

Awesome! Glad it worked for you.

 

[JPMacG]

Had a chance to finish my cross-drilling fixture last weekend. It works well. I used it to make a replacement part - a shaft with through holes oriented at 90 degrees - for the powered feed on my mill. I have a bit of runout on the drive side of the fixture, so the drill vibrates a bit. But the chuck runs true.

 

[Silverbullet]

Be real nice for keyway. Yupper do doit

 

[benmychree]

That's a cool project, Mike. I can think of a couple instances where I could use such a tool.

Did you use the back gears to lock the spindle or do you have a slick indexer for the spindle?

There is a dividing head that mounts into the back end of a lathe spindle, made by Master Mill, I think It has a expanding bushing to grip the ID of the spindle and a torque arm to hold the body stationary; I have one, but never have used it; It would be used in conjunction with their powered milling attachment. I was fortunate to be asked to participate in a estate sale, to price some of the machine related items; the place was a real treasure trove, the man had been a college machine shop teacher and in that capacity was able to "survey" surplus for the school; as it turned out, it was whatever quantity for the school and at least two for him; in his SDA community, most of the prospective buyers were a pretty thrifty lot, so much left over that we got for very cheap, including most of the Master lathe milling setup, and I also found missing items on e bay, so have nearly all of it. Now, if I could just figure out a job to do with it!