Model Engineer Beam Engine - Reeves Kit

[Propforward]

Finally back to making an actual engine.

The ME Beam is a very pretty engine when finished, with quite a lot going on. As a basis I am using the Reeves offering of castings, which I purchased about 2 years ago I think. My initial look over the castings says they are OK - not warped or twisted or anything so I'm looking forward to an enjoyable, completely trouble free and relaxing experience.

Don't worry, I can usually steer myself down paths that bring their own trouble and woes.

So all I've done so far is spend some time with the base plate. As seems normal on casting kits, the way the parts are dimensioned is largely inappropriate, and if not interpreted correctly could steer the unwary quite wrong I think.

For now all I've done is best condition the casting and skim the underside flat. Hey - it's a start. this done in such a way as to maintain enough machining stock on the top side features to get everything where it needs to be.

Best conditioning is the term we used at my last job to essentially balance the set up of a weldment or casting for the best combination of maximum machining stock on all features that get machined, while at the same time not distorting the part with clamping, and then also maintaining visual appeal as needed. What it means in this case is that I measured the casting all over as well as probing it with a height gauge on my surface plate to figure out how twisted / distorted it was. In reality actually pretty decent - about 25 thou variation across the main surface that is to be unfinished, same on the underside, with about 1/16" of stock on most surfaces, so pretty easy to level up and get going on.

The numbers on the casting represent height differences in thousandths of an inch from one corner.

Then up on the mill and skimmed the underside a few thou at a time until it cleaned up. I'd established that the center square feature where the column goes is actually the least out of flat, and indeed that resulted in only skimming about .020" off the highest point to get full clean up. I supported the part on a couple of machinist jacks as well to stop it flexing during cutting. It was a bit of a lightly clamped set up so I just took it really easy. After checking the finished cut on the surface plate there is no rock, so now I can get it clamped really well, best condition it on the table and start on real features.

Not much of a start - on the other hand quite the setting of the foundation.

I see I need to get back into the swing of taking pictures as I go. Blasted YouTube channel has me focusing more on that than still pics. In due course there will be video offerings as well but man they take some work editing.

 

[Propforward]

I think I've put this in the wrong section. What's the difference between "Building them" and "showing them - work in progress"?

I guess I don't mind either way - if this thread gets moved to the build logs step by step that is certainly just fine.

 

[Richard Hed]

I think I've put this in the wrong section. What's the difference between "Building them" and "showing them - work in progress"?

I guess I don't mind either way - if this thread gets moved to the build logs step by step that is certainly just fine.

I didn't even know there was a difference.

 

[Propforward]

If there is a difference, I don't know what it is - and I don't think it matters a whole lot. Not nearly as much as actually making the engine. That's what matters. I just got finished re-dimensioning the plan for the base, so I'll be setting that up and going at it with reckless abandon soon enough.

 

[Propforward]

Stumbling forward at a breakneck pace, I actually clamped the base to the mill table tonight. It is clamped on top of a sacrificial aluminium plate which has been skimmed flat on both sides.

In order to get it lined up and ready I indicated the 4 red surfaces (edges) of the raised square, and the two long sides (blue).

I didn't drag the indicator - just went in and touched at several points along these edges, checking the DRO for offset. The part is basically within .005 along each of these 4 edges. They are surprisingly straight, which is why I used them. This is about as evenly set up as I can get it.

With it aligned, I will establish the center of the raised square in both the X and Y directions, and that will be the datum for drilling all the holes. Seems to me that basically everything on the engine is relative to the center of the beam column (and therefore beam pivot).

The heights of the various steps on the base will all be machined relative to the machined top of the square also. In this way, all these machined surfaces will be parallel to each other, so that everything is as square and true as it can be when assembled. What I am going for here, is an engine that runs without having to do much "bedding in".

So I started re-dimensioning the drawing to better show that and make for an easier reference. I did it long hand, by just doing the basic maths and writing it out on a copy of the drawing, but it started getting far too messy and I couldn't read my own writing.

It was more legible to make a basic model and show all the features using ordinates - and I can plot this out nice and big.

Also - I am using UNC and UNF threads instead of BA threads, just because of tap and fastener availability. I did a comparison of BA thread OD's and TPI numbers against the UNC and UNF series and found threads that are close enough. Not equivalent - they won't play together - they are just physically very similar in size. Should work out OK.

Then my evening of shed time ran out. So maybe tomorrow I can actually get some machining done. It's all in the prep anyway - do that right and the machining goes much more smoothly.