Member postings for David K

Diffuser.
The engine works similar to a 2 stroke in that the fuel is fed into the crankcase and then
transferred to the inlet ports.
The diffuser is basically a fan designed to push the fuel mixture around the crankcase.

Then after a de burr and clean I pressed in a bronze bush , fitted an adjusting screw
and then fitted them to the cyl head.

You can also see the valve caps I made but forgot to take pics.

To finish the rockers I then carefully milled the sides down to size

Each rocker is then parted off

The profile can be seen here

and then tapped m2 for the adjusting screws

Next a set of 1.6mm holes are drilled

Rather than make each rocker individually I machined the rocker profile along a piece
of bar and then parted off each rocker from the bar.
Starting off with a 22mm round piece of Stainless mounted in the lathe , faced off and centre drilled
both ends then a 5mm hole is drilled then reamed through the centre.
The piece is then mounted on the mill using the rotary table and start milling the shape.

Cheers Ryan

The crank was cut from EN8 round bar and turned between centres.

I could have used a 4 jaw but that option is gone now really as I don't want to risk it.

On the plus side I have wanted a tool grinder for a while so now I will get on with making one.

Yes , I made some aluminium packers , I also tried replacing the revolving steady with a fixed and various amounts of pressure from the tailstock. Its been very frustrating , especially as the big ends came out so nice.

Well the crank has not gone well. I ground a form tool as described and cut the four big ends first.

I achieved a nice finish with the lathe and then just ran some wet/dry around to polish the bearing.

Then I set up for the Mains , no matter how I tried I suffered vibration and a poor finish.

I tried adjusting tool height, different speeds , re grinding tool bits, ect but could not get the finish I achieved with the Big ends. I am now at the stage were I do not have enough material left to risk another bad cut so I am going to make up grinding wheel and see if I can save it by grinding down to size.

I am thinking the problem may be from cutting the Webs and Big ends first , weakening the crank and causing it to flex [vibrate]

Edited By David Kenyon 2 on 11/01/2019 13:20:25

Then repeat to make six plus two spare

Part of the valve

Flip the valve in the collet and using a grinding stone finish the valve face

Next turn the top slide to 45 degrees and cut the valve face

Now reduce the shaft for the whole length of the valve until a nice fit into the guide

Valves first start off with a length of silver steel

Reduce the shaft to just over the valve shaft diameter then cut the groove for the collet.

Hopefully when the rings are removed they will stay with the gap formed and have
a little 'spring'
The rings on the bottom are heat treated , the rings above are not.

The top is fitted and the whole 'oven' is heated to cherry red and then allowed to cool.

The rings need heat treating , to do this I made a small 'oven' out of the same cast iron.

the oven is loaded with rings which holds them open for a 'ring gap'