Has anybody built Beng's Danni Steam engine.

Please check out how I have mounted the cylinder in the mill slide and comment if this is correct. I have removed 1.0mm from one section taking 0.25mm at a time. I am using about 600 RPM on the lathe ; it seems to be working.

Brian, Success at last. How anyone at Bengs could suggest that 'the flat' could be achieved with a file is beyond me. (Though apparently apprentices at Rolls Royce in the early 20th century had to be able to file a one inch square on a round shaft, to earn their papers.) Anyway, with the vertical slide, for you and the Danni engine hopefully it'll be all plain sailing from here on in!

In the meantime I've been trying to post a photo of my progress making a scratch-built twin cylinder version of the Danni, alongside the single cylinder kit - which still has a long way to go - but I can't access my photo album when I try to post it to the forum. I might have to ask my son how to do it.

Lawrie : I wonder how long it would take to file the flat by hand ?

It is progressing slowly : the only problem I am having at the moment is the top of the cylinder is pulling slightly away from the mill slide towards the cutter (about 0.5mm). I will experiment tomorrow with better mounting methods than the brass bars I am using now.

''A one inch square on a round shaft'' : Was that brass or steel ? Did anybody on this forum have to do that in their apprenticeship ?

A colleague took an apprenticeship where they had to make a 25mm square on a round shaft. Most assumed it was to be filed. He couldn't be bothered with the effort and milled it. On the basis that only someone determined to go out of business would file it in this day and age, and being a bit portly, it was also too much like hard work. He got full marks for the assignment, and the maximum for anyone filing it was 50%. The deduction was for lack of initiative.

Have you noticed, frequently the best machinists are the laziest people? They find the quickest and least effort way to do things. A bit of thinking can save lots of effort.

Regards

Richard.

'A one inch square on a round shaft'' : Was that brass or steel ? Did anybody on this forum have to do that in their apprenticeship ?

It would have been steel. the majority of engineering firms in the UK would have the apprentices doing something similar. We had to cut a square hole in 1/2 " plate then ( drilled then chiselled and filed square ) then had to file a square on a round bar to fit. In those days a fitter was expected to be able to use a chisel and a file correctly

Roy

Edited By roy entwistle on 30/07/2017 11:40:00

Edited By roy entwistle on 30/07/2017 11:44:14

Hi Brian, I reckon I would try to grip the ends of the cylinder with not quite parallel brass jaws - so the outside of the jaw grips (with a bit of clearance) towards the slide. Sort of clamping the work piece against the slide. It would involve making a shallow angle (a couple of degrees) chamfer on the brass jaws. But then, what would I know. My only qualifications are in economics!

I think the expression I might be looking for is "pulling it into a taper"!

It is only a face to be soldered so not that hard to file to a suitable flatness, the solder will take up any slight variations.

Brian I would take the bottom packing out and move the lower jaw up if needed. You may also need to tap the cylinder back against the slide as you tighten up the screws

I was worried that if I took the bottom packing out then the steel jaws of the vice might leave some sort of mark or indentation on the brass. I am going to try a larger piece of thick, flat aluminium for both top and bottom if I can find something suitable from NORWELD tomorrow.

Edited By Brian John on 30/07/2017 14:01:30

Brian, for soft jaws on the vice you don't want them very thick at all 1.5 mm aluminium would be ok, the square bars will tend to tilt, and(for me) brass is too expensive to use that way(its next to gold in my workshop).

You should be able to file that flat in 10/15 minutes with a good file not used on steel.

Ian S C

I found some small aluminium strips today at Norweld but they have still not solved the problem of the top coming slightly away from the milling vice.

I have to make the flat 4mm from the edge of the cylinder. How do I measure that without removing the work piece from the vice ? I cannot get my digital vernier in there and I am trying to avoid removing the cylinder all the time.

I am advancing the carriage by 0.25mm at a time, How much of the 12mm cutting bit should I be using when taking a cut : 1/8, 1/4, 1/2 ....the whole thing ? Using the whole bit tends to cause it to dig in as you can see from the photo.

This is my practise cylinder so I can afford to experiment a little on this one. I still have two more cylinders to mill after this ( I am building two engines at once).

Edited By Brian John on 31/07/2017 08:25:42

As I said tap the cylinder back against the slide as you tighten up the clamping screws.

Make a not of the handwheel setting when the cutter first contacts the work and then it will be easy to feed it in a toatl of 4mm (16 cuts @ 0.25mm)

For the roughing cuts go about 2/3 the cutter width so 8mm again as I said earlier start with light cuts and see how it goes, if you are getting dig ins then reduce the cut.

Filing it would be easy with a filing rest, something that has gone out of fashion now everyone has a milling machine.

Starting with a nice bastard cut file, that wouldn't take long in brass.

Neil

Yes, I was thinking that myself but can you even buy a filing rest now ? How much do they cost ?

Brian John It's not a lot of trouble to make one

If you know what you are doing.....

I never heard of anyone buying one

Neil

I made one, it's very simple, just two rollers and a hight adjustable pillar, with a base that clamps to the lathe bed. You just have to scale it to fit your lathe.

Ian S C

So I have modified that top piece of aluminium so there is no overhang obscuring my vision (photo1) and I finished milling the first cylinder (photo 2). You can see where I had a bit of a dig in but when the steam chest is fitted this will not be visible as it will be underneath. It should not affect the operation of the engine. Hopefully my next two cylinders will turn out even better than this. Definitely only 0.25mm cuts on my machine !

The cylinder still has to be drilled at tapped at each end for the cylinder covers then two holes drilled in the milled flat surface. I will then have to smooth out the inside of the cylinder after the drill bit has gone through and remove the ragged edges from the holes. I should have left polishing the inside of the cylinder until last !

Edited By Brian John on 01/08/2017 08:06:40

Mea culpa, mea culpa. I admit to purchasing one for my Cowells ME90. Very nicely made as one would expect if a little pricey. However, it does go very well with all the other accessories.

I must however make one for the Myford which is more likely to be used in anger (or more likely thrown across the floor in disgust, couples with the use of Old English, when I make a boo boo while constructing it).

Possibly coming in at number 96 on the list of things to do (in the workshop not around the house) unless a sudden need arises .....

Pero