Saturday, September 9, 2023

Dial Indicator Adapters for the South Bend

I've been working on a rotary broach kit from Hemingway.  As I started the phase of making the first broach, I encountered a bit of a problem.  The collet set I'm using requires me to get fairly close to the headstock, and the micrometer doesn't actually fit in the space I have to subsist in.

I need a new way to measure.

I grabbed some cut-off chunks (and "scrap parts") I had laying around and built two of them.  One of them connects to the V-ways like we normally see, but the other one uses two 1/4"-20 holes right above the gear box.  This would allow me to offset a dial indicator much farther away.  I had a gits oiler right there, so I needed to mill around it.

First was getting the parts to square.  Then, machining out a slope and the v on the moveable indicator holder.  I then drilled and tapped 1/4"-20 holes in two directions for the dial indicators (specifically so I could orient the dial indicators as either facing upward or facing outward), and cut grooves so that the indicators can nestle down in and be secure.  At that point, I drilled (and counter bored) a 3/8"-16 through hole in the middle, and machined the bottom clamping jaw out of a scrap bin part.

Once that one was complete, I ran a cut-off block through the mill to square it up as well as notch for the gits, and used transfer screws to set the drill points for this new block.  I did have to make a few tweaks, but I also drilled and tapped two 1/4"-20 holes to hold the dial indicator.  This dial indicator was only going to face upward.  Here they are without the indicators attached.

Here they are with dial indicators on them.

These will be absolutely sufficient for my next steps on the broach - cutting the broaches to exact length.  Here is the micrometer attachment, showing the length (which is how much it obstructed the carriage movement).

This is a win, and allowed me to continue on the broach project.

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