You have made a nice job of that. The bit of extra effort to add the details lifts it above just another barstock engine.

Small flywheels can always be a bit of an issue as they are a bit hard to get into with a boring bar and the typical reamers while Ok for bearings where you want a bit of a running fit tend to make flywheels a bit loose. A second grub screw at 180deg or two at 120deg spacing may allow you to tweak the minor wobble.

What’s next?

Mark

Flywheels are the very devil on such small engines, a couple of thou run out stands out a county mile when its running and draws the eye like supercooled electromagnet. Even more so when nicely polished.

Once you’ve seen the runout you can’t unsee it either.

Which totally spoils the, justly earned in your case, satisfaction of making a nice job of the engine.

Best practice with grub screws is two at 90° which gives wobble free results so long as the fit is close to slip with both bore and shaft nicely finished.

Gotta say I’m a bit unconvinced as to whether these very small engines are the best subject for a neophyte having to simultaneously learn to both machine parts and coax the best out of a machine well past the first flush of youth with the inevitable vagaries of operation and execution. In absolute terms the actual size of any errors is likely to be pretty constant but on an engine twice the size they will show up half as much.

When it comes to cylinder boring it’s far harder to do a 20 mm one than a 50 mm one. Quite apart from the difficulties of getting the right shape on a tiny boring tool it’s a darn sight easier to see whats going on inside the larger bore. Concerning boring tools it would have made my life far easier on many occasions if someone had told me Jasons trick of using an end mill at a slight angle ages ago. 1974 sounds about right!

Tolerance rings are well worth remembering about. They can be got right down to 4 mm diameter and are great for recovering things should you sneeze at the wrong moment and overcut. Far as I’m concerned whatever works is good and the screaming purists can go back to their “best howler monkey impersonation” competition. At least they seem to have finally accepted loctite.

Although regrettably rare the hand squeezed “nutcracker” type three wheel  knurling tools are great when it comes to converting a nice slip fit to something a bit more grippy. A quick squeeze leaving a very shallow pattern is just the job for tuning easy slide into nice stiff push ready for two grub screws or loctite for final hold. I’d really miss mine.

Clive

With more and more beginners starting with new machines then they may not have the problem of them being a bit old in the tooth. Likewise these days a 20mm dia hole can be cut quite easily with an insert boring bar without the need to worry about grinding it correctly and many a beginner tends to now go down that route.

The big advantage of a smallish engine from barstock is that you will not break the bank if you much something up, stock to make a 50mm cylinder with it’s associated longer length could be 10times that of a piece to make a 20mm cylinder.

Regarding Elmers designs, if you prefer metric and as you have been in construction industry then I expect that is what you are used to a simple conversion is to let 1/32″ on Elmers drawings equal 1mm. That way you get a slightly larger engine but more importantly most sizes will be in increments of 1mm, a few od 0.5mm if he used 64ths or you are placing something either side of a ctr line.

Very Nice ! As clive has said a light knurl and a drop of loctite might solve the wobble. Noel.

Your first engine is a lovely job and the drawings and video are excellent.  With Journeyman’s permission, SMEE will be making examples of this Elmer’s No 19 at MMEX 2024 using his drawings as a demonstration of a beginner’s project.  We hope to attract newcomers to the hobby by showing a relatively low-cost way to get started.  We shall be delighted if visitors to the show want call by and talk about their experiences making this or similar projects.  Elliot Hirst – Chairman SMEE

Wow…..the extra effort paid off in droves, looks fantastic.