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| NickG:
Hi all, I've finally found some motivation to pick this project back up. The week I had on leave was ruined by the bedroom redesign and at the end of that weekend we all caught some sort of cold but this wouldn't shift. Still got remains of it now nearly 2 weeks later which is pretty rare for me. I tried a couple of times to go into the workshop but I simply didn't have the energy. Anyway, tonight I felt full of life and enthusiasm which was good! Tonight's job was the two cylinder pillars, I'd already made a start on one but didn't take any pics of the machining, it was straight forward turning, the critical dimension from the base to the thread shoulder. As long as it's high enough to give the flywheel clearance, they are both the same and I make the bearing blocks the corresponding height that is all that matters. Also getting the thread straight was critical. Here's one of them. The one thing I am doing is getting better at forward planning with the more experience I get. At one time I wouldn't have put undercuts on and chamfer on the end of thread then I'd wonder why it wouldn't screw all the way home. I tried to part this stainless off but didn't like the noises coming from it so chickened out and sawed them off, turned them around and faced to length. For the undercut I used a hacksaw as again, the thin grooving tool was having none of it. I think I'd ground it from a bit of duff HSS that I had overheated at some stage by grinding too hard as it was all blue / brown colour. Pretty chuffed with the result, everything looks very square. This meant I had time to turn the bushes for the valve rod. Luckily I found some bronze (I think) off some old balance scales which was almost the right size. Carefully turned it down to size and drilled it. My valve rod is actually 3/32" not 2mm so just got the nearest oversize number drill and it gives a nice sliding fit. Here they are assembled, rod was marginally tight at first but a few strokes up and down and it’s a lovely sliding fit now, drops through but doesn’t wobble. I may need to loctite these in as it was more of a push fit than a tight press fit. Am very impressed the way this has gone so far. Apart from my blunder on the cylinder, it’s gone very well so I am just waiting for something bad to happen! The pistons may not be a good enough fit yet though but they are fairly simple to remake if need be. Next on the list is the valve rod, drill the hole in the valve and the rod control at the other end. Then finish the piston off, bearings, conrod, crank and base! Still a long way to go, I don’t know why I am so optimistic with timings when I start out, you’d think I would know by now! Nick |
| bogstandard:
You're going about it the right way Nick. If it ain't critical, use what you have to hand. I have seen people searching for weeks to find exactly what is needed for a build, and all they had to do is look in their bitsa box for something close enough. The only reason a lot of certain sizes are used on plans is that is what the designer had to hand when he built it. If he had found something different, he would have used that. At least you can now say it isn't built exactly to plan, you modified them to suit your own ideas. John |
| sbwhart:
Going well Nick that looks a nice finish on the cast iron cylinder. You probably know but there is more than one way to get the screw down onto the the shoulder, you can use a washer or you can slightly countersink the female thread. Have fun Stew |
| NickG:
John, I think I remember the guy asking now if 3/32" would be ok! I actually bought most of the materials for this project - first time ever to save routing around and hacking big chunks out of unknown stuff. It's paid off so far as the material I have bought cuts superbly. The bitsa box is still required though, I normally get everything from there! Like you say though, it'd be as easy for people to just slightly adapt things to suit what is easily available - crazy searching for ages! There are only a few minor differences in my design but mainly to suit the flywheel, because of its large diameter the con rod will need to be longer. Anything else is just simplified, if Jan has 2 steps on something, I only have the 1 that is required! I will have 1 piece bearing blocks too. Hopefully it won't detract from the appearance too much, don't think it will. Stew, the cast iron seems to be a nice bit of material, gives a very smooth finish then a bit of wet & dry gives a nice shine to it. Good point, I might try the counterskink way next time, might be easier in a lot of circumstances. Thanks for your interest guys. Nick |
| bogstandard:
Just a note Nick, if you haven't already made the little striker adjuster that is on the end of that rod you have shown. The original is a real PITA to adjust and keep tight. If you want a piccy of mine that I used, and it works great, let me know. John |
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