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Elmers #25, my first engine project
spuddevans:
Ok, managed to get a couple of hours in the workshop today. Started off by setting up and drilling the offset hole for the crank pin.
The more observant of you will have noticed that the Crank-disc is not properly seated on the 3-2-1 block and so did not drill square :doh:. I didnt notice that until I'd finished today and as I'll explain in a bit I may have to re-bore the pin-hole square.
Anyway, after that I found a use for the screwed-up piston, I turned it down to make the crankshaft bush shown below in the middle of the other hacked out bits.
I then chucked up a length of 6mm 303 stainless to turn down for the crankshaft, I turned down to 5mm for the main shaft and a short section 4mm to fit the crank-disc.
Then I did something similar for the Crank-pin, except I started with some 4mm stainless, turned it down to 2.4mm for the press fit into the crankdisc and 2.3mm for the easyfit into the conrod.
I also pressed the crankshaft bush into the frame, after I cleaned up the frame,
then did a little assembly just for fun.
Once I did the assembly and tried to turn over the crank I found that it was sticking at TDC and BDC :bang: After a little wondering I checked the squareness of the crank-pin ( it's amazing how hard it is to use a 4" engineers square on a part that's only 17mm wide and the pin's only 3.5mm high !!)
I then realised that the crank-pin is not square and is what is binding up twice per revolution. I've not totally decided what to do about this. I could pull the pin out and re-bore the hole wider and square and then make a new pin to fit. Or to just try and bend the pin to square. I'm leaning towards just pulling the pin and reboring and then make a new pin.
That's all for today, It's getting exciting now, I can nearly smell the finish line ( I like mixing metaphors ) :lol:
Tim
bogstandard:
Just get a bit of say 1/4" rod about 3" long. Face the end and drill a hole in the end the same size as the crankpin.
Use that to tweak the pin straight. When the faced off bit of rod is sitting perfectly flush on the crankdisk, you should be square.
Bogs
spuddevans:
--- Quote from: bogstandard on May 15, 2009, 04:11:24 PM ---Just get a bit of say 1/4" rod about 3" long. Face the end and drill a hole in the end the same size as the crankpin.
Use that to tweak the pin straight. When the faced off bit of rod is sitting perfectly flush on the crankdisk, you should be square.
Bogs
--- End quote ---
What a great tip :thumbup: :clap: :thumbup: :clap: I'll try that tomorrow.
Thanks Bogs :thumbup:
Tim
spuddevans:
Yesterday I managed to make a start on the flywheel, and got one side shaped (to a fashion :scratch:), and today I bored and reamed the 5mm hole for the crankshaft, then remounted to machine the other side, centred it using the 5mm hole as a reference and then shaped the 2nd side. ( I was so excited about getting so close to completion I forgot to take any pics of these parts :) )
I then turned a some 6mm brass rod to a close fit for the flywheel, and threaded the end M5, and mounted the flywheel to it to clean up the rim and make sure (hopefully) that I dont have a wobbly flywheel.
After that I drilled and tapped the flywheel for the setscrew
I then turned to the air-intake-to-aquarium-type-tubing-adaptor-thingy. I used the same 6mm brass rod and turned some down to 4mm and then threaded it M4 and then bored it through with a 2.2mm bit
Then after some jiggery-pokey with a parting tool,
it was over to the spin-indexer to make a nut-shaped bit.
At this point I did a quick mock-up of all the parts and positioned the crank for transferring the hole position from the exhaust of the frame to the cylinder. Then after removing the indexer from the mill and clamping down the vice, I drilled the cylinder with a 1.6mm bit.
I then found a spring that was about the right size and assembled all the bits together, and here's the result.
( notice the immaculate chatter on the flywheel )
The other side
Imagine my joy, now to get it running. But how? I have a little air compressor, but no way to attach the length of 3mm (id) tubing to it :bang:
So I decided to build an adaptor. I just copied the connector off one of my air-nailer, and bored a 4mm hole up the centre.
I then made another air-intake-to-aquarium-type-tubing-adaptor-thingy as above, except I haven't milled the nut-shaped-bit on it yet as I had to come in to make me grub, and that's all I got done.
So that's all I've got for you today, hopefully I'll get it running in the next couple of days and then I can post up a video for you all to laugh look at :lol:
Tim
sbwhart:
Can we have a count down to lift off 5-4-3-2-purrrrrrrrrrrrr :nrocks:
Good luck
Stew
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