Gallery, Projects and General > The Design Shop
An experimental engine
ozzie46:
OOOH BOOOY another must watch thread. :D :D
I'm ready for another swell ride.
Ron
Bernd:
Arnold,
Very interesting. Going to follow this one closley since I'm interested in O gauge.
Very nice work so far. Like the CA glue idea. Looks like it works well.
Bernd
arnoldb:
Thanks everyone :beer: - I didn't expect this big a response!
Stew, I used Charlie Dokstader's Valve Gear program and supplied my own dimensions until I got a convenient solution. It's brilliant stuff to study valve gears, different dimensions and how it all affects engine operation :thumbup:
Bernd, I can't take the credit for the CA glue idea - but it is very useful. Just use a known-good quality brand to avoid the problems I had with the cheap $h1t - that bottle's going into reserve to repair hang nails - if it's good for that even; otherwise I'll be vindictive and squirt it out on top of the trash in the wheelie-bin - as a surprise for rummagers...
I'll hold up a bit on this for a week or so; I'll first build some tooling that will make the rest of this project easier :dremel: - I'll post that up as well to annoy you fellows :coffee:. Things are a bit hectic at my work; a project that must be finalised by the weekend of the 17th, so shop time might be restricted. I've learned to stay out of the shop if I'm mentally tired...
:beer:, Arnold
arnoldb:
Well, no tooling was made, but a little progress on the project was :)
First things first though... My 40 year old Myford was still running with its original motor V-belt - it needed replacing badly:
::) I forgot to convert its size to "Metric" before I went shopping; just jotted down the imperial size and didn't think to take along the original. First thing the salesman told me is "We don't sell Imperial v-belts" ::) So I borrowed his calculator, and got him the "metric" size - well, closest over and under sizes from his stock list & bought both as I couldn't remember if the Myford was closer to its short or long adjustment for the belt. The longer one works perfectly (even though a certain salesman is convinced a metric V-belt cant work on imperial machinery). The old girl is running as smooth as I ever heard her - it was time for this belt change and I think I can expect better surface finishes and easier parting off now :D
On to the project, and first off, I milled 1.5mm wide by 1.5mm deep port holes at the top of the cylinder bores to start the steam passages from:
...tool gloat... - As the port passages needed to be drilled at an angle to meet up with the slots on top of the cylinder, I calculated the angles - 10.8degrees, and brought out my "Christmas Present" - a precision protractor I found in a 2'nd hand shop just before Christmas:
Mitutoyo 187-901 protractor set in mint condition for US$60 - sometimes I get lucky! :ddb:
I used the protractor to set the valve block at the calculated 10.8 degrees off vertical:
Then used a 1mm center drill to spot a starting hole to drill the steam passage in the milled out bit on the cylinder:
And drilled the steam passage with a 1.3mm drill - checking from the side for break-through into the steam port on the top of the block:
::) These macro photos can really light up the minutest imperfections and scratches on a surface!
The steam passages came out OK - with no additional break-through into the cylinder bores, and closely bottoming out in the steam ports on the top of the block:
Looks like a dog's breakfast on close-up - I need to improve my skills.
One problem I found with my design so far is for the exhaust ports. I need to be able to pipe the exhaust from the cylinder blocks back to the boiler smoke box later on to help create draft there. On most cylinder designs I've seen so far, the exhaust is in-line with the exhaust port, but I didn't leave enough room, so another angled hole was needed from the port face to where I could fit the exhaust connection pipe. I decided that I'm not going with a threaded exhaust connection; a Loctite fit would be fine, as the exhaust side of the engine won't be under pressure, so I drilled a 3.2mm hole 4mm deep into the block from the side to receive the available copper piping I have:
Then I calculated and set the angle to drill the passage hole through from the port face to the exhaust hole. Made a horrible boo-boo on the first one by drilling the angled passage hole all the way right through to the outside of the cylinder block :bang: :
Well, Warts & All is what you get :lol:
The second one went better; I remembered to use a bit of rod shoved into the hole and held there to "feel" for break-through into the exhaust hole:
When the drill breaks through into the hole, the bit of rod wiggles.
Photographing down holes is a problem in macro mode... I was hoping to show how the port passage hole was nicely centered in the exhaust hole - if you squint, have a vivid imagination, and take a couple of grains of salt along with that, you might be able to make it out ::):
On to try and recover the bad port hole. I first counter bored across both the holes with a 4mm center cutting end mill. A 5mm would have been ideal, but I don't have one, and a 6mm (which I have) is too big, as it would likely break through into the cylinder bore on the one side. A drill bit would have wandered so I couldn't drill it out:
And a :doh: moment while typing this up... I could have just counter bored it like I did and then opened up the hole with a 5mm drill afterwards ::) - too late now!
I then turned down and parted off some aluminium rod (salvaged from an old TV antenna directors :big:) for a press fit into the counter bored hole:
I left the parting pip on - it's useful while handling small bits...
Then with a lavish coating of loctite pressed the slug into the hole with the mill vise. The pip squashed a bit flat in the process :lol::
After cleaning off the excess loctite and material from the pressed-in bit, things looked like this:
There's a small artifact left on both sides from the old holes - that's why I would have preferred a bigger hole initially to mend my erroneous ways...
I finished today's shop time by re-drilling the exhaust hole at 3.2mm to depth through the repaired section:
So nothing much for today, and much less pretty, but it _IS_ experimental after all :)
Regards, Arnold
saw:
I just love you're photos and the way you are writing. :clap:
Keep going. :nrocks:
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