Paul,
There is a clearance between the big end and crankdisc which will be big enough for the fillet of solder.
When the engine is made and tested, I will update the drawings to suit the practices I used to make the working engine, I may have to change a few things along the way, so will see what happens!
Anyway, I have finally made a start on it, however, I should point out that unless I have a very busy Christmas Eve in the workshop, this is going to be a late Christmas present! Please see some progress below, I may have gone into too much detail to start off with here so will have to review the way I am going to present this!
Well, first of all, I think this lot will need tidying a little!
This was partly to blame ... the caput starter motor from my Renault 5 GT Turbo, think I've sorted it but that's another story and another project! The rest of the mess on the lathe was due to a favour I did for someone at work ... turning down a 2" diameter lump of mild steel, counter bored at one end and cross drilled, then parted off. Except I couldn't part it off as I didn't have a good enough grip on it, so had to saw it by hand with a very used hacksaw blade!
Anyway, no more digression from now on, I promise!
After / inbetween tidying up, I found some materials ... probably not what I state on the drawings but not too bothered. The drawings state what the materials should be, I use what I have! The brass plate is for the frame, mild steel for crankshaft, round brass for piston / cyl. cover, square brass for cylinder and I found some cast gunmetal bar which I will use for the flywheel. Copper pipe is for inlet / exhaust, bronze bar was going to be for crankpin / cyl. pivot rod but I wasn't thinking straight, I will use some mild steel. I would usually use silver steel for that sort of thing but not sure how well it will solder to brass and I find it's a pain to turn at very small diameters (as Marv says, I could use loctite but don't have any ... could even use araldite, that's strong stuff but need to make sure it stays where it's meant to!
I started on the flywheel as I'm not keen on sheet metal work, I find that boring!
Gunmetal chucked, faced and OD roughed. I noticed there are some blow holes even this far under the surface of the casting ... hopefully they would disappear as I got to finished diameter. The surface finish wasn't quite as good as I'd have liked as I was using a cutting tool with wrong radius and rake angle really, the reason for this was to try and use the same cutting tool all the way through to save set up time ... this could backfire!
Turned to finished OD and the boss machined, ready to centre drill, drill (I'm not superstitious but why did it have to be No. 13 drill that I needed before reaming!) and ream for crankshaft hole.
Successfully parted off (or is it? You can see component underneath bed!) under power cross-feed. I have found setting the feed to slowest and spindle speed about 200rpm works best for me. Gives a nice constant feed, better than I can do by hand.
At this point I was considering leaving the flywheel as it was because I knew I'd have problems putting it back in the chuck (my 3 jaw is very worn). However, I decided to go ahead and try to make it how I'd designed it as there were some chatter marks from the parting tool so I at least needed to skim it. Luckily the first place I gripped it, it appeard to be running ture!I started trying to counterbore but ran into problems. There wasn't enough clearance around the tool so as I got deeper, it started catching the edge of the hole. So my plan had backfired, I needed to change the cutting tool! This chafing also had the effect of moving the flywheel in the chuck ... d'oh!
After grinding trying another cutting tool and messing it up even more, I decided to grind one properly which gave good results.
I was quite chuffed until I looked at the rear ... the chuck jaws have quite badly marked the boss (can't see on this photo), I've dressed with a needle file and it'll do, but I always get this problem, does anybody have any advice concerning this? Other than that, fairly pleased, just need to drill and tap the hole for the grub screw. I've put 6ba on the drawing but not sure whether this may be too big, might go for 8ba.
I think I've made this far too detailed ... all this for a flywheel! :-[ From now on I'll just post a couple of pics on each component with less waffle! Oh, forgot to say, there is still some very slight evidence of blowholes so it obviously isn't a great piece of gunmetal.
Crankshaft and frame will be next, not sure whether I'll get anything done tomorrow though!
If anybody has any suggestions on the way I'm posting I'll be happy to take the advice as clearly I haven't done this before!
If I don't get on here tomorrow, Merry Christmas to all, I hope everybody has a good day.
Nick