25 cc Horizontal Engine

[fumopuc]

Hi Roger, good to see you back in business. Always following along.

[Roger B]

A few more stages in building the base. When I started on this I realised that I had not used a fizzle stick for at least 10 years so there was a steep learning curve especially as I was using a DC inverter and an automatic helmet rather than my old transformer and flip down  .

In the end it looks like it will clean up ok and most important the top surface is flat to the accuracy of my (Swiss) garage floor. I can't check the base until I have filed a few blobs off.

There will be a fair amount of filing followed by some fun with a flycutter.

[fumopuc]

Hi Roger, donīt worry. Some JB weld will fix it finally and nobody will be able to look behind it.

[Roger B]

How to machine a part that is much to big for the machine (well actually it just fits) and the power feed helps a lot.

[Roger B]

I've finally finished flycutting the base. I had to play around with the setup to get it rigid enough and to find enough travel. The solution was to swing the head a little to get enough gap between the backplate and the cutter and to remove the leadscrew protection tube at the tailstock end.

The final surface has a few small gouges, probably due to lack of rigidity, but laid flat on the surface plate. Due to the amount of twist one of the feet ended up a bit thin so I will cut it off and weld a new one on. 

Next stage flycut the top surface for the bearings and cylinder and then square up the ends.

[Roger B]

I've flycut the top surface of the baseplate and milled the ends square(r). There was more heat distortion from the welding than I had hoped, but it will be useable and with a little cosmetic work should be ok. I still need to cut off the thin mounting lug and weld on a new one. That should clean up with some local end milling rather than needing a complete new flycutting operation.

[Jo]

That looks rather big for her

Pleased to see she's earning her keep 

Jo

[Roger B]

Absolutely on the limit, but it worked 

[Roger B]

I think that the original was probably machined in one pass on the Harrison horizontal mill at my 6th form college rather than over several days at 0.1mm per pass with a flycutter.

On the other hand I don't think that Monica from upstairs would have been able to help carry the delivery driver carry a Harrison into the cellar 

[Roger B]

Moving on with this one. My original thoughts were to try and move the timing gears inside the frame. The more I looked at it it seemed to offer less benefits and more problems. I decided to stay with the original concept and could start cutting metal again.

Next up are the main bearing pedestals. These are made from a piece of 15 x 50 mm of what I thought was BDMS. It seems (once again) to be something tougher than I thought. I have been able to work it, but it needs slow speeds and good cuts, under 0.5mm just skids. I roughed it out with a hacksaw and a good Bahco/Sandvik blade and slowly milled the rest.

It was generally ok until I came to radius the top of the bearing caps. I decided to cut straight to the required radius with a 6mm end mill on the rotary table increasing the depth 1mm per pass. The first one will need a bit of JB weld or similar as 1) I didn't use a centre cutting end mill and 2) I didn't lock the rotary table before increasing the depth. It's all about learning  .

The next pieces are the mounts for the cylinder. I am now trying to decide whether to try and cut the radius on the rotary table or with a boring head?

[Jo]

Its looking more and more like an engine Roger 

I still think that it is rather big for the small machine tools you own.

Jo

[Roger B]

I still think that it is rather big for the small machine tools you own.

Jo

Absolutely on the limit is a better way of putting it 

[Roger B]

The next stage was to cut the caps off the pedestals with a hacksaw and then mill the faces flat. When I laid then out I drilled a 3mm pilot hole for both the pedestal and the cap. After cutting and milling a 3 mm drill was a snug fit in both pedestals and the caps were well aligned with the bases 

I have decided to bore the bearing holes on the faceplate in the lathe, so the next step will be to make the cylinder mounts before I go back to lathe mode.

[Roger B]

I managed to complete the cylinder mounts today. I am still not sure if I picked the best option for machining the radius. The others would have been clamp to the faceplate and bore in the lathe or use a boring head. Both would have meant interrupted cuts.

My 12mm end mill is now definitely in need of sharpening or replacing 

[Roger B]

On with the bearing pedestals. The tapping fixture took the worry out of breaking a tap in something I had spent so much time on. As Arnold said the Volkel taps glide through quite tough stuff (as long as you don't bend them  ). I then made my first studs from my not quite straight did of 5mm ss. The Volkel 5mm die also just glided through.

Onto the lathe for boring out to 16mm for the bronze bushes. I have previously had problems boring, but splashed out on a proper renewable insert boring bar and some ss cutting inserts from ATP. Wonderful, on size, and excellent surface finish. If you ran the tool through a second time it didn't cut  . With my previous bars/setups it would still be cutting on the forth pass.

Next stage some bronze cotton reels and shavings everywhere