Ade,
I'm looking forward to seeing it run for the first time (which, I'm sure, will be the first time you try it).
I doubt that it will run first time, but I am doing everything to eliminate things that might stop it running, so hopefully it will only require some fine tuning.
I had forgotten that the head had to be made before getting everything set up in the mill again, so here are the bits again. I need to take just over 1/4" off the bar of cast iron and that will then go into stock, a nice little freebie supplied with the kit.
The bar was again mounted up into my 4 jaw self centring and the head was turned to dimensions on the end of it.
I also drilled a hole in the centre, just deep enough for the parting tool to hit. That helps a lot with parting off, especially with these large diameters, the tool doesn't have to reach all the way to the middle, which is the area that cutting failure usually starts to cause problems.
It parted off just fine.
It fitted into the sleeve nice and snug.
I had a choice now. The instructions said that the end face of the cylinder head had to be as flat and as smooth as possible. If it wasn't that way, and it was left roughish, it would act like a file on the graphite block that is used as the sliding flame hole cover, and it would last no time at all.
I could either get that flat and smooth face by ten minutes on the surface grinder, or an hour with a lapping plate. I thought the grinder would be the better choice for me.
So not only was it flatted off, but it was taken down to the correct thickness, which saved another setup and facing job on the lathe.
Smooth and flat, just the job.
It was at this point I started to do a bit of forwards planning. The head required six mounting holes drilling into it, plus the flame hole needed to be machined. Once that was done, the holes were then to be transferred onto both the sleeve and the water hopper (keeping everything in the correct orientation). IMHO, a cock up waiting to happen.
So I first superglued the sleeve into the hopper.
NOW it was time to get it set up in the mill.
BTW, if you do have the opportunity to obtain one of these coaxial jobbies, I can thoroughly recommend them. This one is spot on, and has saved me hours on set up times. But they do take up a bit of throat space, so no use on the smaller mill or lathe.
The newly made head was then superglued into the sleeve, and a weight added for ten minutes, giving it enough time to make the joint.
I use superglue a lot for little jobs such as this, where there aren't heavy machining forces involved.
Using the coordinate feature of my DRO, I spotted then drilled down into the hopper with the correct size for tapping.
Then a quickie calculation and set up, I followed down with an end mill of the right clearance size for the fastener exactly to the depth of the head and sleeve flange.
The plans call for 5BA bolts, but I actually prefer something like this to be held with studs and nuts, so I am using 3mm studs, with washers and nuts, to give a nice neat fixing.
By doing it the way I did above, I could now reach down with a tap and finish off the threads in the water hopper by hand.
That then allowed me to use some screws to hold everything together, so that it could resist the cutting forces to come. The superglue was now redundant
The flame slot was first milled out with a one size smaller cutter, the correct size one was then used. You will get a more accurate hole and better finish by doing it this way.
Job done.
Four operations combined into one, guaranteeing that everything is in the correct position.
A few seconds heat from a blowtorch soon broke the grip of the superglue, and when cooled down, it can be peeled off the surfaces with a fingernail.
These parts will now be put away for a while, as other bits need to be made.
I will make the decision as to which ones next time I get in the shop.
Bogs
