Elmer's Kimble engine

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arnoldb:
Thanks Dave :beer: :beer:

A bit more progress; this is turning into a weekends-only project it seems...

With all the hard-to-do parts done, I don't know how long the yet-to-be-made parts will take to do, but soon I'll have to start assembling bits and pieces to see if everything fits. The base and sub-base picked up a bit of rust earlier on, and there were a couple of dings in them as well. The dings were my own fault - I didn't follow the rules of scrupulously cleaning the mill vise each time a part was moved, and some swarf got trapped and made dents.

So first I cleaned up the dings - had to lightly mill away the sides of both the base and sub base to get rid of them:

Then I set to with a file and some scotch-brite to remove the last major machining marks and all the rust from the bits, and gave them a coat of primer:

In the previous post I mentioned I might make the eccentric ring a split one, so I grabbed a bit of 3mm brass plate and roughly laid it out:

After picturing the finished part in my mind on the completed engine, I decided against making the split eccentric ring; it would look a bit "chunky" against the rest of the engine. The smallest taps and screws I have are 10BA, and even If I used these to close the eccentric ring, I'd have to turn down their heads just to fit, and they'd still look overly large.
I do have 1.4mm taps, but no die nut, and if I want to single-point turn screws for these, I first have to make some tools, which have to wait for another day.

So, back to a simple ring for the eccentric ring, and a bit of phosphor bronze turned down to outside diameter - I nearly grabbed a bit of aluminium bronze I have for this part, but remembered in time that I had to silver solder on it!:

After a bit of drilling, and boring, things were to size, with the step turned in to match the one I made on the eccentric:

There was nearly a brown-pants moment while drilling the bronze... I'd forgotten I recently bought a new 10mm drill bit, and it's still very nice and sharp... It grabbed into the bronze, pulling the tailstock chuck right out of the tailstock taper. I grabbed the old chipped 10mm drill, and roughly stoned its cutting faces to a more suitable profile for bronze and finished the job.

The eccentric fits a treat - turning closely, but smoothly in the ring, with the eccentric face _just_ protruding a bit:

Next I parted the ring off:

It was about 0.05mm too thick after parting off, so I flat-lapped that off on some emery, and ended up with this:

Elmer's plans call for 1.6mm (1/16") plate for the valve rod and connecting rods. I thought I had 1.6mm brass plate - well I thought wrong :coffee:. I have 1.2mm and 2mm. For a while I sat debating with myself whether to maybe make the rods from round rod, but decided against that as well. So, I'll use the 2mm plate, and I cut some strips from it:

Then trimmed the valve rod to width - 4mm in this case, leaving it about 0.02mm over size for final finishing:

I love my digital camera to bits; it takes fairly good photos without even trying hard, and it'll take 500 to 800 photos on a single full charge, but one thing I don't like about it is the fact that it'll suddenly show the low-battery-of-doom indicator, and only take two photos before shutting down completely on low battery. The last time the batteries ran out was last year when I was finishing the second Coomber, and I didn't give the batteries a full charge... You have three guesses what happened today, and the first two don't count.

Without photos while the batteries were recharging a bit, I silver soldered the eccentric ring to the eccentric rod, and cleaned it up a bit:

I didn't notice it in the shop; but the photo shows some interesting things colour wise. Both the eccentric ring and flywheel rim are phosphor bronze, but of two different compositions - I say that because they behaved a bit differently while machining. The rim has a bit of patina on it already, but is more yellow than the eccentric ring which is more copper in colour, suggesting a higher copper content in the alloy of the ring. Next the yellow of the brass eccentric rod follows. There's also the different grays - ranging from the darker shade of the silver steel eccentric (maybe indicative of it's high carbon content) to the zinc colour of the galvanized screw, then the aluminium approaching "white" and finally the silver sliver of high-content silver in the joint between the bronze ring and brass "rod".

Regards, Arnold

cfellows:
Nice project, Arnold. Wouldn't mind seeing a couple more pictures of that dividing head if you find the time...

Chuck

saw:
Nice work as usual Arnold :thumbup: :thumbup: :thumbup:

arnoldb:
Thanks Chuck & Benni :beer:

I'll post today's bit in an hour or so.

In the meantime, here you go Chuck:
Just for a bit of background...
I'ts a genuine Myford dividing head - has a 60 tooth worm wheel rather than the more common 40 tooth on most available DHs.
The separate bit in the pictures is it's own tailstock - it slides into the one open hole that can be seen in some of the photos.
The adapter plate it's mounted on at the bottom is actually a bit I made myself - it was originally a cross-slide extension piece for use on my lathe, but now it's a quick way to mount the DH in the mill vise; I plonk it down on a pair of parallels and clamp it up, and I'm good to go for "general accuracy will do" jobs.
As it has the same spindle nose as my lathe, it's very quick to unscrew the chuck from the lathe and transfer it to the DH, and I can use any of the lathe chucks or face plate on the DH to hold things.
Photos - if there's any bits you'd like more detail on or a different angle, feel free to ask:

:beer:, Arnold

arnoldb:
Today's bit - I think it's an hour or so later :lol:

One thing I didn't do when I made the vane shaft was mill out flats on it for the vane arm setscrews - that was easily done:

Then I spent some time with the base - flattening the primer a bit with some 1200 emery, and gave everything the first coat of paint:

Next I marked out the vane arms on some brass flat bar:

And drilled and reamed the vane rod holes:

Then I sawed both bits off the parent stock, and with a bit of 6mm rod trough the holes clamped them together in a small vise, then removed the rod and clamped them up with a toolmaker's clamp that's narrower than the workpieces:

The clamp could then be clamped in the mill vise, with the bits lying flat on top, and I drilled a 2.5mm hole trough to tap M3 - this keeps the connecting rod offsets exactly the same for both vane arms:
Elmer's plans use 2mm pins here - cross drilled for using a piece of thin wire as a retainer, but I had enough fun with that method on my Grasshopper engine; I prefer screws and bolts.

I used a bit of rod and the 2.5mm drill to keep the pieces aligned, and clamped them up in the vise so that the center line is horizontal to the vise jaws:

Then drilled the top 2.5m mto thread M3 for set screws:

While I was about it, I just tapped the holes as well:

Next I used some bits 'n bobs to get things set up to mill away the sides:

And off to the big vise to file the rounds; it takes me longer to set up something to machine curves like these than it does to just file them to the line, and where it's a cosmetic feature like here, a file's plenty good enough:

After a quick rub on emery, things look presentable:

The arms needed a bit taken off on the one face of each; rather than set up the rotary table for this, I did it on the lathe:

Arms finished:

And where they fit on the vane; I'll have to shorten the set screws a bit:

:beer:, Arnold

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