If it is very thin, as to be used for decorative capping, you could solder it to a flat bar to hold it, maybe using a very low melting point solder to minimise heat warp.

Also consider using brass screws if you do use screws so that they can be machined into if necessary/in error.

Edited By Bazyle on 03/03/2023 10:21:01

Quick piccy may help with suggested setup. Sounds a bit like a crankshaft balance weight to me. You could saw off most of the "waste" material and save it for a rainy day 

Edited By JasonB on 03/03/2023 11:02:23

Angle grinder just over half way would leave you 2 bits

In a lathe with a decent 4 jaw and a sharp tool you can face it down and turn the extra into swarf

Edited By Ady1 on 03/03/2023 11:30:29

If I want a really accurate square face I use the lathe and face it down

Make sure its well secured andproperly flat, take your time

The other question is how are you going to machine the slot in it to attach the upright piece? Clamp it in the toolpost with a milling cutter held in the lathe chuck?

It seems like a needlessly tricky little bit of machining all up for such a simple engine. I might be tempted to use a bit of square brass bar and make life easier. Just mill the slot in it and be done.

Or could you mill the slot in the round bar first, then attach the upright piece to the round bar and hold the upright in the four jaw chuck while machining the round bar down half-round? Can't tell from the pics how that is secured though. Might not be strong enough?

Re the cylinder: That one is only a small flat. Yes holding in the four jaw and facing with a sharp tool will do that one easy enough.

Edited By Hopper on 03/03/2023 12:01:23

It seems like a needlessly tricky little bit of machining all up for such a simple engine.

From the ebay listing:

“YOU WILL NEED THE USE OF A SMALL LATHE AND MILLING MACHINE AND BE ABLE TO SILVER SOLDER.”

So maybe not such an easy starter project with just a lathe?

File? That were luxury that were. We would have rubbed it on concrete floor of workshop until it were beautiful and smooth.

On the other hand, an important part of engineering is finding the best/easiest/most efficient/most effective way of doing a job.

But to stick with using the original material to hand and stick to the plan for the sake of learning, I reckon you could grab the round bar in the four jaw chuck and face it down to almost halfway, or close-ish to it. Then drill and file your slot. Then silver solder, or even soft solder, the upright standard into the slot. Then you could grip the standard in the four jaw and face off the last bit from the half round bar to bring the flat down to the centreline. Very fine cuts with a very sharp tool would be required, I should think.

But as the kit's advertisement says it is designed to be done with a milling machine, I think I would compromise if using only a lathe and go with a piece of square bar that is easier to deal with and will look just fine. You could even file the ends to 45 degrees (or rub them on the concrete floor!) to dress it up a bit.

Very true but you have to be reasonable as to how large a step there is between what a beginner already knows how to do and what they need to learn for the next job. Too big a step or too many steps leads to, at best, disillusionment with unattractive results and all too often compete failure. Too much of that and a new hobby will be sought.

Unnecessary multiplication of complication, whether in design, construction or work holding should be avoided wherever possible. Which goes in spades for novice projects. That half circle part is tricky problem in work holding that has no place in a project intended for the inexperienced. There are so many ways it can go wrong. Certainly way too much trouble for pure cosmetics.

I would obtain a piece of 5/8 x 5/16 flat bar and reduce it to whatever shape seems pleasing. Whether using a longer piece and turning it half circle as suggested in my previous post, filing the corners taper or simply radiusing the edges. Option 3 for me!

With the blank prepared mount it in the four jaw chuck with the flat face hard against at least two jaw stops so the basic slot shape can be produced by drilling a line of holes. You may need a scrap behind the job to keep the drill away from the jaws. The easy way to get the sideways step is to use a scrap of material as a setting gauge. Loosen one of the jaws holding it longways, insert the "gauge", bring the jaw back to lightly touch it, remove the gauge and use the opposite jaw to push the part over so its gripped ready for the next hole. Loosen the short ways jaws a touch so it slides without rocking.

Drill alternate holes so the is a gap between the holes drilled in the first run. Start with a centre drill to give a decent lead in. If the web between the holes is significantly smaller than the drill diameter find something to make decently fitting plugs to help keep the drill true. Brass would be best but alloy, steel or even JB weld will work. As ever with brass the drill needs to be decently sharp.

If you do decide to make it half circle as per plans first file a flat almost as wide as the slot will be so the drill has a nice clean start. Brass is skiddy at the best of times. Starting on a curved surface is an open invitation to trouble. A three flute centre cutting end mill, such as the old Clarkson throw-away series would be better than a drill for producing the the holes. Probably too short to go right through in that size but one will give a nice clean round guide hole most of the way through to finish with a drill.

Clive