poppin engine started and stopped!!!

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jim:
Nick,
i made the bits to go in the flywheel today, i really would recommend doing that as a one peice flywheel!

did the piston, took a very long time polishing to size, i reckon its got a few tenths clearance, not sure if thats going to be too tight :scratch:

i was going turn a central recess on the piston, to reduce drag. but as you've pointed out, i need to walk before running!!!

i was going to mark out the cam and cut/file to size, the idea of using the rotary table is one i will be using :thumbup:

i want to get the crank done next (i've been putting it off), when i get the bandsaw going i'll do the frame for it. i think thats going to be the most involved part of this engine. i'm going to make a few alterations to this (but keep the dimensions the same).

biggest problem i'm having is not knowing what i can get away with sizes, at work i get a drawing with limits on :lol:

i'm looking forward to your "got it running!" post :proj:

NickG:
Jim,

Yeah, couldn't really see the point of the flywheel hubs - fair enough if you're going to use that tapered collet method, I wonder if it's just so he could get the grub screw in normal to the bore. Might as well turn in one at the same setting while it's all running true etc.

Not a bad idea on the piston might hold some oil in there too. What material is your piston / cylinder from and how did you lap / polish them them?

Will be interested to see your take on the crank then, you planning on cutting and machining from solid then? I think that's a step too far for me, I'll try the fabricated method!

Yes, since I started work I've yearned for model engineering drawings that are fully toleranced! Still - I'd probably have no way of measuring some of the geometric ones so doesn't really matter I guess! It'd give a nice warm feeling if we were making things inside the limits though :lol:

Fingers crossed. Other people have done it successfully so it can only be my fault really!

Nick

jim:
made a bit more progress, still no bandsaw bearings :(

so rather than spend ages sawing some ally by hand, i found a bit that is (just) big enough, i'll have to mount it on a stepped base later now.

its a work in progress :lol: :lol:

i still need to drill a couple of holes for the valve bits.
making a bearing for the "big end" caused a small problem on clearance, but just needed to mill an extra bit of clearance, so no problem.

spins over ok and if i put my finger over the hole in the cylinder head, it won't turn over, its got a very good seal :thumbup:

jim:

--- Quote from: NickG on December 27, 2009, 01:29:50 PM ---Not a bad idea on the piston might hold some oil in there too. What material is your piston / cylinder from and how did you lap / polish them them?

Will be interested to see your take on the crank then, you planning on cutting and machining from solid then? I think that's a step too far for me, I'll try the fabricated method!

--- End quote ---

too be honest, i'm not sure what material i've used. told an old guy at work what i was doing and they gave some some bits of bar, it cut ok(ish) :scratch:
i've done the crank to the drawing, it runs well. i'm learning a lot as i do this and having thoughts on my next engine. this one could be done by next weekend.

i've been really inspired by your engine :thumbup:

Stilldrillin:
By `ek Jim!

That`s looking good...... :clap:

David D

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