Saturday, March 26, 2011

Making tools to make tools for my machine tools.

I bought an independently adjustable 4-jaw chuck for my lathe.  The chuck came with an adapter plate, but my lathe (Emco Compact 5 CNC) is a bit special and didn't fit the adapter plate.  The bolt holes for my lathe were half in the center hole on the adapter plate. The solution?  Another adapter plate, of course!

This adapter plate is made from some 2" aluminum round stock.  It moves the bolt holes out in diameter just enough that they will hit the stock adapter plate that came with the chuck.  When I went to machine the outer diameter, I discovered that my carriage doesn't go that close to the headstock.  My toolchanger takes boring bars, but they all have the cutting edge on the wrong side.  The solution, of course, is a custom tool!

I ground some drill rod to make a cutting edge, then heated it with a blowtorch and quenched it in water.  Considering I'd never done any of those things before, it went very well.  The tool is shown in the above picture ready to take its first cut.  I should have ground the heel a bit more, but it did cut and I was able to cut the outer diameter properly.

The stock adapter plate also needed some modification.  Remember how I said the bolt holes for the Emco headstock were  half in the center hole of the stock adapter plate?  Well, I need access to those bolts to tighten the whole thing to the lathe.  The stock plate is cast iron, which I'd never machined before.  I read up on it a bit, got out my boring bar (first time using this tool too!), and slowly cut openings in this adapter to allow access to the bolts on my adapter.  I didn't use a boring head, as the diameter from the boring bar itself was exactly what I wanted.

Then I needed to drill and tap the other 4 holes for bolts that would hold the stock adapter to my adapter.  I figured the best way to get the drilling lined up with my adapter would be to use a transfer punch... but I don't have any... so I built one!

I took some more drill rod, turned it down to just under the diameter of my bolt holes, and left a sharp pip on the end.  After heating this up and quenching it, I had a brand new transfer punch!
This, of course, was immediately used to locate the drilling spots on the stock adapter plate that would be used to attach it to my adapter plate.

If you look closely in the next pic, you can see the center punch marks in the cast iron.  They are in between the channels I bored out earlier.
I then drilled and tapped the holes.  Cast iron is really easy to machine, although you have to spend some time cleaning all of the gritty powder off your machine and tools when you are done.

Success!  These two adapter plates stay bolted together and essentially make one adapter.  When I want to change to the new chuck, I just bolt these adapters to the lathe and then bolt the chuck on.

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