I am hoping to be doing some boring between centers on my next engine to achieve a long true bore for the cylinder. A friend and fellow model engineer helpfully showed me a picture of a device had had made to measure reach of the cutter from the boring bar. This is only part one and I hope to finish it shortly, it has taken much much longer than expected, probably because my efforts working on the bar have been split into lots of little spells in the workshop… anyway, hopefully finish tomorrow evening. The plans for this device are in a back edition of model engineer.

A piece of scrap ally I rescued months ago!

The main 2 pieces cut to shape with the guide rods. I deviated from the plans here which stated to bore 1/4″ and loctite the guide rods into the top T shaped piece. I didn`t fancy that, so I decided to only drill 2/3 of the way through the top piece and thread the top of the guide and screw it in position. Will probably use some thread lock on final assembly. I`m pleased with this, it looks tidy (not drilled through) and certainly solid. It also can be disassembled should it need to be.

This sort of shows how it will work. The two V slots will clamp down onto the boring bar with them bolted together using the guide bars. I now need to make a plate on the top which will hold a DTI and a plate on the bottom which will hold the adjusting screw.

Hopefully it will be obvious how it is used once complete!

PART 2
I finally completed the boring bar setting device after many more hours than expected.

Here are all the parts required. I have used stock M3 screws for the supporting brackets and a stock M4 screw for the grub screw to hold the dial in place.

The plans also required that a flat button is made for the DTI in use so that you can measure the maximum projection of the boring bar

Initial mock setup on a piece of ally bar. I`ll be using a steel bar for the boring bar when I get around to cutting it. It works by turning the screw at the bottom which will push the tool steel through the boring bar and the DTI will measure the distance and therefore the bore radius.

And a final assembly