Boring large holes/product review

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Boring large holes/product review

Post by rudd » Sat Jun 15, 2019 1:42 pm

I'm s l o w l y building a live steam loke. The engine I am modeling has the sloped cylinders, Argent 3. No castings avail. of course. I'm building up the steam chest/valve/cylinder assy out of cast iron. Cylinders are 2.75" OD, and will be silver soldered into the steam chest. I tried this first with the vertical mill and had less than good results, not enough quill feed, no power quill, difficult to hold the blank at the proper 5 degree angle one way and keep it dead square the other.

I had decided it would be easier to drill the hole first, then do the milling with a nice squared up block.

I thought of boring in the lathe, but I could not find a way to securely hold the block of cast iron on the faceplate at the required angle. Plus I probably would have dinged the faceplate.

So, I decided to use the lathe as an ersatz horizontal boring machine and make use of the APT Multi-tool set I've pieced together. This is the "E" size, it starts with a 1" hole. If you have power to drill a 1" hole, you can drill a 3" hole. They make a "D" series that starts with 3/4" hole, not sure how big you can go with that.
First a piece of aluminum tooling plate and a duplicate "spigot" of what is under the compound.
Drilled a 1" hole with an MT drill, then used the multi-tool to pop that up to 2". Below I am going from the 2" hole to the full 2 3/4". The tool uses a series of bushings/pilots as the hole gets bigger.

The drilling went fine, when I started with the first blade on the multi-tool, it wanted to jerk the cross slide back and forth because I was entering the hole at an angle. I used the taper attachment to steady it - I just did not clamp the TA to the bed, so no taper.
Coming out the back side was a bit "interesting" on the 2" hole, but went much smoother with a fresh sharp blade on the 2 3/4" hole.
The finish is, well, a drilled hole. Which should be about right for silver soldering.
I'd also made a "between centers" boring bar in case things went south, but ended up not using it.
I had decided it would be easier to drill the hole first, then do the milling with a nice squared up block.
table 1.jpg

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Re: Boring large holes/product review

Post by spro » Sun Jun 16, 2019 11:44 pm

Very well thought out and very creative. Even your machine table had to be made certain height. We can see the four bolts of the tapered "spud" which is locked tight by three tapered bolts in the cross slide. I just think it worked out fine with replaceable pilots and you were ready to go a different way. Neat.

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