Model Engineer Beam Engine - Reeves Kit

[propforward]

Finally back to making an actual engine.

This is one of "the usual offerings" so likely not very interesting to the elite but I'm doing it anyway. I think 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.

[simplyloco]

Finally back to making an actual engine.:

This is one of "the usual offerings" so likely not very interesting to the elite.

No such movement on this forum. Good luck with your build and I look forward to seeing your progress.
JB

[propforward]

Thank you. Hopefully I can do it justice. I always start off with big ideas and end up having to make compromises.

[Michael S.]

A good start.
I'm watching with great interest because I also want to build this engine.

Michael

[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.

[Jasonb]

How does the casting compare with the drawings particularly lengthways? I'm not sure it was always supplied as an aluminium casting so the pattern may have been made to suit the shrinkage of iron.

[propforward]

Thanks for looking in Jason. It seems like the casting is on the large side, by between .03" and .05" depending on where and what is being measured. So small features are long / oversize by about .03", distances from center vary between .03 and .05 as you move further out. This is good from a height standpoint as it means there is a little more material to take off and keep everything correct, but it means a bit of thought needed for the hole patterns. If I just establish center of the square plinth and use that, then everything will work and all patterns will be aligned relative to each other, but the circular pattern on the cylinder boss will definitely not be concentric to the boss. May not be so important when everything is bolted in place.

Anyway, likely what I will do is split the difference between the square and round plinths. Once assembled that shouldn't show up particularly. I can always dust off the outsides of the cast features also, although I'd rather leave those as cast.

Likely putting too much effort into this balancing act but I enjoy it and ultimately should make for a nice fitting engine. Need to double check the beam casting before starting to make sure the bosses on that are close enough. I really don't want to alter engine dimensions though. I recall doing that when I first got the castings and don't recall any red flags, so should be OK.

The only thing that likely won't be made to print is the very outside dimensions, and locations of bolt down holes in the oval tabs. Those I will best fit to the cast features and merely dust off the outsides the minimum needed to clean and square it up. For sure if I went with drawing dims the outside would eat into the oval feature and several of the holes would be off visually.

Hoping to cut metal tonight - but a big trip coming up so I need to prep for that, so may be a week or two before this makes any real progress.

EDIT: The supplied plans show this as an iron casting, so yes indeed this is a change from original. Maybe because the iron one was too undersized and / or twisted? Also or maybe solely on cost.

[propforward]

Hehe - I see I've got a dimension snapped to the end of a center line rather than a hole center. A few things to check there before I cut anything! This is one of the pitfalls of redrawing stuff.

[Michael S.]

Hi Stuart, I don't know if my pictures will be of any use to you to check the size of the base. I don't know what year the aluminum base is from either.

Michael

[propforward]

Thank you Michael! I’ll do a comparison tonight. Looks like I’ll be able to get enough time to make start on actually cutting.

[propforward]

So next bit was simple enough really - touch off on the highest feature (having first measured heights of all the features to know what was to come off), fix the quill, touch off by raising the knee, establish the highest plane and raise the knee accordingly to clean off the other surfaces.

One feature had to be centered and machined on the width also to accept a bearing block later on.

This just shows my scratch where I recorded data about stock and heights etc.



Then the machined article. Ran out of time now so can't get the various holes in at the moment, but it's all set up well for that.





Hoping to be able to knock out a video on it in some down time later.

[crueby]

Nice start on the engine bed!   

[Roger B]

Off to a good start    I trust that the castings were well fondled before the first cuts  

[Michael S.]

The starting signal has been fired. Very nice!

Michael

[propforward]

Thanks all - as always I appreciate you looking in and also any comments. I'd also like to point out that I am very interested in what might be construed as negative feedback if it's presented fairly - as in alternative approaches or where I might be setting myself up for failure later on. It's a result of such feedback that I have managed to improve my techniques.

Also - a big THANK YOU to Michael, who behind the scenes has sent me some additional information he has acquired on this engine which is helping me determine the design intent behind some features, that are not immediately obvious from the Reeves plans. Also - the Reeves drawings have had a few details removed since the original ones were punlished.

Aaaaaaaaaaaaaaaaaaaaand here's the video, which explains better than the post what I am trying to do. Need to up my game on making detailed posts as well as improving my machining.


<a href="https://www.youtube.com/watch?v=VvIcZMrOlEo" target="_blank">http://www.youtube.com/watch?v=VvIcZMrOlEo</a>