I am now proficient at boring! Both to size and to depth, without a DRO. There are 6 bearings to counter bore for and a hole to prep for tapping M12x1.5.
The general sequence for each hole was to align the workpiece to the collet/spindle using an 8mm HSS ground tool rod. The table height was fixed after the first alignment process. Once the work could move on the rod easily, I switched out to the boring head. I found a 0.7mm depth of cut was my limit for stressing the head and its small 6mm bar. After lots of setting changes to get to the correct diameter, it was on to the next hole.
Emboldened by progress so far, without any significant whoopsies or rework, I proceeded to the 2 main supports.
Having recently bought a paper copy of Textbook of Advanced Machine Work, I had seen how planning out work was a relatively straight forward but necessary step. The book is replete with Sequence of Operations charts, mostly starting with “oil the machine” I planned out the sequence of operations so that I didn’t machine myself into a “can’t get there from here” scenario.
To that end I sized and squared up the 2 main support pieces. I marked out the 3 shaft holes and drilled then using a N drill, followed by an 8mm reamer. This allows me to use some 8mm ground HSS tool steel as alignment pins.
After a too long absence from making this engine, today some real progress. From my other posts you will have seen that I now have a real milling machine. I took some time to sort that machine out and make some enhancements. Now I am taking advantage of those improvements.
The Outer Shaft Support is fairly simple, most of its lines are cosmetic in nature. Or a test of your machining and setup skills or both I had already learned to make a Sequence of Operations for parts, doing so means you don’t machine yourself into a corner where you can no longer hold the part!
I was hoping to buy these but they are a weird size. The machine came with a couple of hacked up ones, and 3 different sized bolts as well to add to the mix.
A piece of 1/2×3/4 steel was cut to just over 3” length. This gives me 4 nuts 3/4” long and 0.025” for 3 saw cuts.
Some careful markup on the metal provided the guides I needed to make this the correct size. Measuring at close stages resulted in a symmetrical part. A bit of careful work with a centre punch meant that the bolt holes were centered in the slot. I tapped these 5/16×18 for a set of studs and standoffs that I hope to buy later this year. This is the first time that I used power tapping, what a joy compared to using a tap handle. A blip or two on the drill press power switch does the job. Only works for through holes though.
This was the first real test of my milling machine and my skills. The result is quite decent. And lots learned about the machine and its capabilities.
The horizontal milling machine has a stop on the X axis (left-right movement). This allows setting the travel within preset limits. Unfortunately only the LH adjustable limit came with the machine.
So today I made a RH one. Essentially a mirror image of the LH one, it is made from 1/2×3/4 steel. A 5/16” end mill did the hard work, with my coolant mister keeping things cool and lubricated.
The t-nut to hold the limit in place was made from a bolt. A bit of lathe work resulted in the final part working perfectly. One step closer to working on that model engine again!