Elmer's Kimble engine

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DaveH:
Arnold,

You do some excellent workmanship, it's a very pleasant learning experience to follow your posts.

Very nicely done and shown :bow: :bow: :bow:

Thanks
:beer:
DaveH

arnoldb:
:beer: Thanks very much Dave

This afternoon I made some small bits. As I mentioned earlier, I'm not going to use Elmer's "pin with hole and soft wire" method for retaining the connecting rods and valve rod. So it was time to start making screws.

First up, a small screw for linking the valve rod with the valve arm. I started with some 4mm silver steel and turned a 2.5mm step on it to match the hole in the crank arm, and then a 2mm step to thread M2:

If you look carefully at the photo, the first section of the smallest step is undersize; I'd overshot and turned it down to 1.8mm - which wouldn't do as that is too small for an adequate M2 thread. It's great for getting an easy and straight start to the thread though :)

After threading with the tailstock die holder, I turned off the excess 1.8mm bit, and parted of the screw. It just needs a slot:

Next, some 5mm silver steel - turned with a 4mm and 3mm step, and threaded M3:

That was parted off, and repeated another 3 times.

If you look carefully at the previous photo, you'll notice that the 3mm thread does not run to the shoulder. Normally, one would make an undercut there for a crank screw like this, but I'm a lazy rotter and didn't want to grind up a narrow enough cutting bit for the undercut. Anyway, the crank rods need some slight spacing off the webs and crank arms, so I rather set about making some 0.5mm thick brass washers - ID 3mm and OD 6mm.
If one first drill the brass rod and then part off the washers, each is left with a burr on the side that must be filed down; a real pain. So I used a method that leaves much less burrs in a case like this.
I first made all the parting cuts - leaving the core at just under 3mm. The first section was a bit thick ::):

Then I center drilled the end, and drilled a 1.5mm pilot hole through - the pilot hole is needed to prevent the 3mm drill from wandering around for the next step. Then I just drilled down the lot with the 3mm drill, and all the washers are left on it with a minimum of burring:

This is what the bunch of washers look like without any clean-up whatsoever:

Next I slotted all the screws - not the ideal setup to do it with, but it worked:

For today's shop session, I ended up with this lot:

Not as much as I'd hoped to get done, but I spent about 1 1/2 hours at one point searching for my ER11 collet closer nut after dropping it, the collet that was in it and the screw that was in that :bang: :bang: I never knew these things were made from rubber; everything bounced all over the show, and not having chameleon-like eyes it's impossible to follow the flight paths of three madly bouncing bits at the same time :palm:
I eventually found the nut - there's an old V6 engine standing between my lathe and mill at this point, and the nut had lodged between the water pump and its pulley:

:lol: I've found another entrance to the fourth dimension!

:beer:, Arnold

doubleboost:
Hi
Arnald
Those screws are aw sum :thumbup: :thumbup: :thumbup:
Every one should have a old V6 under the bench :lol: :lol:
John

arnoldb:
:beer: Thanks John. :lol: :lol: :lol: - That lump of Essex is standing in my way all the time; I'd better find a use for it :lol: :lol: :lol:

Today's bit; more fiddly stuff and making screws :loco: .

First a teaser :borg: - I had to assemble things well enough to judge how to bend the front connecting rod, as the perspex engine cover is quite a bit thicker than the cover from the plans:

I then bent the connecting rod to match:

The back one was bent to plans, as I didn't change any measurements there.

Then I drilled the big end holes in both rods:

:( Sorry - out of focus photo!

Next I located the hole against the vise stop and set the mill x handwheel to zero on location:

Then I dialled in the con rod length on the x axis and prepared to center drill:

After center drilling and drilling through at 4mm on the one rod, I flipped them and drilled the other. This made sure they had exactly the same length hole-to-hole in each even though the are bent. It's crucial to get this measurement the same for this engine.

Next I rounded over the ends with a file, and cleaned the lot up with some scotch-brite:

I turned up the main shaft, and loctited the flywheel to it before taking a bit of a lunch break - that gave enough time for the loctite to cure, as it was a nice and warm day today:

One more part required was the vane seal - I prepared some 2mm brass plate for it, and drilled a 0.8mm hole to retain the spring in it:

I need to buy some smaller drills at some point ::)

The vane seal was then sawn off from the parent stock, and filed and lapped to size. Elmer specifies some very thin stainless wire to make a spring from. I don't have that, and I was thinking of using a bit of thin high "E" guitar string for that, but I couldn't find the bit I stole off the guitar - till I remembered I used it to repair the cheese slicer. Then my eyes fell on the big wire brush, and I clipped one of it's bristles off and bent that to the spring shape - that's the thin black part in the photo:

The valve rod still needed a hole drilled and tapped M2 for connecting to the valve arm - that followed:

I'd originally intended to use some 2mm all-thread "studs" and nuts to mount the engine top to the body as I didn't have long enough M2 screws for the job, but as everything else on the engine now use slotted screws, that would look a bit out of place. So I chucked some 4mm silver steel in the ER11 chuck, and turned it down to 1.95mm diameter 13mm long, and filed a good cone on the end to allow the M2 tailstock die to start easily Then I turned a short section down to 3mm - that will make the screw head:

When turning down thin long sections like this, it's imperative to hone the toolbit to a very sharp edge on all cutting edges - then lathe max RPM (~640 for my Myford) and a smooth and steady hand feed to keep a consistent thin chip coming off. Works a treat, but seems to take a bit of practice. I need to build myself a box tool like Tel showed over on HMEM.

Thread, part off & repeat 3 more times, and I had this lot - just needs slotting:

::) The one on the right's head is a bit big... I forgot to turn it down to 3mm :lol:

Easily fixed:

I'm really starting to enjoy the ER11 collet chuck working along with my ER25 chuck like this for small jobs!

I slotted them the same way as yesterday's screws. Next I turned up the steam connector from some 5mm hex brass:

Then I laid out all the bits and started giving them a once-over to remove the last tooling marks and to make sure everything was there:

:beer: , Arnold

saw:
I am so very impressed of you, you make it so very easy. Nice work :clap: :clap:

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