The Home Machinist!

rmac wrote: ↑Thu Mar 25, 2021 9:59 am Where would you get (or how would you make) a boring bar for something that tiny?

Especially for aluminum, it's really not much of a problem. In spite of the fact that drill shanks are not hardened, they are hardened beyond the flutes, so that area of a drill can be used for other functions if needed. The shank from a broken drill can be used to fashion a simple boring bar, starting with a drill that is smaller than the hole one intends to bore. I have successfully bored a 1/16" diameter hole on a lathe. Needless to say, passes are extremely shallow, and multiple passes may be required.

Remember, your objective is to establish concentricity. Even if you get some deflection, a few light passes through the bore until it has rounded and becomes concentric will yield the desired results. Once concentric, opening the hole to size is easily accomplished (drill or reamer), and if it's critical, it can even be honed.

H

A straight flute carbide bit might help as a tool start, carbide being much stiffer than HSS.

I agree, Russ. And easy to fashion for boring if a diamond wheel is available. To aid clearance, the tool can be operated slightly above center with acceptable results.

H

This is an antique now ( just like me) which I built back when Dr. J. R. Senft first designed the Moriya. This was machined on a 6 inch Atlas lathe back about 1990. I used graphite for the piston and aviation fasteners to keep size up and footprint down. The hot end was originally silver soldered but would not hold up to extended running times so it was rebuilt and tig welded - still the same on it today. BTW: this fan will sit for months - years and with a light lubrication will run sweetly for hours! You have chosen a project that will be a family heirloom. May I attach some photos - just taken..

When Moriya heats up it will speed up if you continue with the same heat. It will begin to show an imbalance and actually dance around on a hard surface. The counter weight that was added (very unscientifically) curtailed that. It is worthy of study for smooth high speed running.

She's a dirty mess with fly specks no doubt but will run just the same...

The displacer piston took the most thought and machine time. I used a piece of 1" OD 304 SS tubing intended for boat handrail tubing. Chucked it and bored it to size and parted it off to length. That was the most time consuming part of this entire project. The displacer piston ends were painstakingly machined and all the parts were pressed together... if they leak it doesn't seem to matter.
The Atlas 618 is not a machine to do any sort of parting tool work on - not rigid enough but the cold end worked without any problem but took a long, long time.You are past all of that and moving along with grand results! You are going to be amazed!! This is such a satisfactory project!
BC

Beautiful creation there, BC.

Thanks, gentlemen, for the hints on making concentric holes. I'm out of the shop for a few days (taxes and houseguests), but I will be back!

In the meantime, a couple more questions:

BClemens: I'm surprised that your silver-soldered hot end failed. What were you using for a heat source?

BClemens and RussN: Will your engines run if they're turned on their sides, so the pistons are moving horizontally instead of vertically? I am imagining that there would be a lot more drag between the displacer piston and the gland in that orientation.

-- Russell Mac

I've never tried running the Moriya engines horizontally.
And I agree with your assessment that friction would increase significantly for the displacer piston rod.

I also wonder about the failure of the silver soldered parts.
I seldom use silver solder with lower than 45% silver, so failures of such joints are not in my experience.
Russ

I used 'SILVALOY' brazing alloy 50...what I have always kept for silver brazing. It looked OK when brazed as I remember. Used small oxyacetylene torch to braze the stainless steel hot end together. I may have completely overheated it with an alcohol burner I made to run Moriya. (I also may have overheated the stainless steel parts when brazing too.) A small section of the seam (cap fit into a step in the tube) basically blew some of the alloy out and it opened. Remade it from scratch using mild steel and TIG'd it together. That was back about 1990 or so. I was relating a problem I had building it... that's all. Thanks guys for reminding me!
BC

Progress Report #11:

Taxes are done and the houseguest was actually interested in the engine (!) so I managed to solve the crooked hole problem and manufacture a couple of satisfactory glands.

I couldn't get the tiny boring bar idea to work. No matter what I tried, the tool wanted to flex more than it wanted to cut. Unfortunately, I didn't have a nice stiff carbide blank to work with, or any way to grind it either. I suspect that might have worked better than the broken drill that I was using..

In the end I followed the suggestion in the plans to make an undersized D bit (a.k.a. "self-guided boring bar") to get a straight hole, and then bring it to final size with a reamer.

My first attempt at a D bit was kind of crude. I'm talking "that looks about right" horsing around with a grinder kind of crude. It didn't work at all. I then learned from a couple of YouTube videos that the business end of the tool has to be just a thousandth or two thicker than half the diameter. So I dragged out the milling machine and the micrometer and did a more careful job on the second one. It worked great.

-- Russell Mac

rmac wrote: ↑Thu Apr 01, 2021 10:06 am I couldn't get the tiny boring bar idea to work. No matter what I tried, the tool wanted to flex more than it wanted to cut.

Generally the result of the tool making contact where it shouldn't.

Nice to read that you achieved your goal, though. Well done.

H

Harold_V wrote: ↑Thu Apr 01, 2021 3:37 pm Generally the result of the tool making contact where it shouldn't.

That could well be what was happening. Working on miniature stuff with a pair of old eyes can be iffy sometimes.

-- Russell Mac