Smaller Monitor-Style Variant Build

[crueby]

After seeing Julius's wonderful plans for a Monitor-style steam engine, it was a very quick decision to build one - the offset angled crank arms give it an intriquing motion. However, given that my machines (Sherline) are better suited to smaller stock, plus given the size of the bar stock I have on hand, I decided to build mine at 80% of the size given in the plans.

Figuring that I might as well build from the ground up, first thing to make was the base frame. After laying it out on a length of steel bar stock, they looked a bit plain, and studying the plans some more, the next decision was to make the base frame out of smaller bars rivetted together. I think that will give it a look more like an engine built up from manageable parts - hope it works out! The base frame does not have many critical dimensions - it holds up the pivot bars at either end on platforms, the cylinders on one side on platforms, and the bearings for the crank shaft down the center. That means there is plenty of leeway to redesign the frames and still have the rest of the plans work out.

So, time to get some chips flying (don't tell the FAA, they'll try and register them as drones!). The frame will be made up of thin steel bar stock for the horizontal members, and wider steel bars vertically. First step (photo 1) was to measure out and rough cut to length all the bars, then use the mill to take them to finished length.

The second and third photos show drilling the rivet holes in the vertical plates that will go at the ends of the frames. I used the edge of the v-notch in the mill vise as a reference point to clamp in each piece the same way, and counted turns on the table handwheel to position the holes. Eight of these plates were made.

Then, simaler steps to drill the holes in the vertical plates in the center of the frames - 8 plates for the outer and 4 of them for the center positions. photo 4.

The horizontal bars were done with matching holes - photo 5 shows drilling the ends using the edge of the vise as a reference point to clamp them all consistently, photo 6 shows the center holes, using another vise as an end-stop to position the bars.

So far, does not look like much, but last two photos show how it all came together once they were riveted up with brass round-head rivets. All the holes lined up well (careful reference points and counting turns on the handwheels paid off), and the end result is a quite rigid frame. The holes along the top edge and the outer ends are the mount holes for the spacer blocks to come later. Just need to rivet up the other 3 sets, and I will go back and mill the holes for the main crank bearings (I wanted to make up the frames, and see if there are any adjustments needed in the positions to make sure the crank holes all line up). Then it will be time to make the spacer blocks that hold the frames in position.Those will be from brass bar, with the ends notched to fit between the gaps in the frames.

Chris

[b.lindsey]

Nice start Chris!  I always enjoy seeing what you are up to on your Sherlines too 

Bill

[vcutajar]

Chris

You're off to a flying start (not the drones).  Will surely be following along and pick up some ideas from your build if it's OK with you.  I like the fabricated look of the frames.

Vince

[crueby]

Chris

You're off to a flying start (not the drones).  Will surely be following along and pick up some ideas from your build if it's OK with you.  I like the fabricated look of the frames.

Vince

Idea away - I get lots of ideas from this place!   

[crueby]

One more operation for today - boring the main bearing holes in the sides of the frames. I bolted the pairs of frames together (and stamped numbers in them to make sure I keep the pairs together later) with some 4-40 bolts through the spacer mount holes, and clamped each pair in the mill vise for boring (with a spacer block underneath to make sure I didnt bore into the vise). A starter hole was drilled, and then the hole taken out the rest of the way with the boring head.

The first boring bar cutter I put in must be getting dull, had to switch to another one. I've never had to sharpen one before, have to look that one up to make sure I do it right. I would guess that grinding back on the flat across the face is the right way to go, otherwise the relief would get messed up?

Anyway, got both sets of frames bored out for the bearings, next step should be to make the spacer blocks that hold the pairs together and then on to the bars that hold the pairs to each other...

[zeeprogrammer]

Well you know I'll be watching.     

You're the second to mention scaling down. I'll be interested in what adjustments you do (I'm kind of figuring that it's not just a simple matter of multiplying everything by some factor. But I don't know.)

So no pressure!

[crueby]

Well you know I'll be watching.     

You're the second to mention scaling down. I'll be interested in what adjustments you do (I'm kind of figuring that it's not just a simple matter of multiplying everything by some factor. But I don't know.)

So no pressure!

Just like I've been following your build too, we are starting at different places so we'll both learn from each other's build! 

So far been just multiplying by 0.80. I'm not too concerned about exact scale, will be rounding off here and there to match closest stock size. The only places that dimensions are critical to match are mating parts, cylinder to piston and cover, crank web to conrod end, etc. The rest can vary a few thousandths without it mattering much. Thats why I am going to build from frame up, so I can fit current/next parts by checking distances as I go. It would be a lot harder to make parts in random order and make it all work out. By looking ahead a few parts it should all work out - have built some complex engines from no plans that way, just working out the critical sizes. Occasionally I get bit, but nothing too serious.    30+ years as a firmware engineer taught me how to plan ahead. Usually...!  That's my story and I'm sticking to it!

It helps that the plans are not a super detailed reproduction of the real engine but is derived as an example of the type. When I do a scale model of a ship or train, then all dimensions are more important!

This style engine is a great bit of mesmerizing eye candy with all the levers, will be fun to watch them take shape.

[b.lindsey]

This style engine is a great bit of mesmerizing eye candy with all the levers, will be fun to watch them take shape.


Yes it will!!  And in stereo no less

Bill

[Don1966]

Well I can say you don't mess around, already starting another project. She sure is shaping up mighty well Chris............

Don

[Dave Otto]

I like the fabricated frames Chris.

I have pulled up a chair and will be following along with this interesting build. 

Dave

[bruedney]

"This style engine is a great bit of mesmerizing eye candy with all the levers, will be fun to watch them take shape."
that is what attracted me to Julius' experimental engine. Levers and uniqueness

[crueby]

"This style engine is a great bit of mesmerizing eye candy with all the levers, will be fun to watch them take shape."
that is what attracted me to Julius' experimental engine. Levers and uniqueness

That one looks like a robot head, will be really fun to watch!

[crueby]

Well I can say you don't mess around, already starting another project. She sure is shaping up mighty well Chris............

Don

Oh yeah, always a couple different things in the works, alternating projects keeps any from getting boring. I've been prototyping a rowing mechanism for an RC rowboat, and working on some carvings too.

[zeeprogrammer]

30+ years as a firmware engineer taught me how to plan ahead. Usually...!  That's my story and I'm sticking to it!

Ah! Well then we have similar stories. 

Hopefully there is no end.

[crueby]

For those Monitor-ing this build, here is next part under way - the spacer blocks that go between the side frames. In the plans he shows long notched blocks at either end, and rods with spacer tubes in the middle. On mine, I am just going to use short spacer blocks both at the ends and in the middle, plus cross bars screwed to the middle ones. At the ends, the upper platform does the same job as the long notched blocks in holding the sides apart. 6 o one, half dozen of the other.

I started with a couple lengths of brass bar stock the right thickness and just a little wider than needed - the width will get taken down to size during the milling. Bars long enough to get 4 spacers from each were clamped side by side in the mill vise, and one end trimmed square. This end was used as a reference point for the rest of the milling. Along the top, notches were cut the same depth as the side bars are thick, and enough room was left between the little posts sticking up to cut/trim each spacer to length. I've found that it is much faster, easier, and more accurate to clamp up longer pieces for making repetitive parts and cut them apart later - fewer times clamping/unclamping things and getting them lined up.

Once all the notches were cut on both sides (making sure the notches lined up one side to the other), I went back and drilled for the bolt holes that will hold everything together - again as a gang operation, spot drilled with a center drill, then going back and drilling them all. Lots of cranking, lots of counting turns...

Last photo shows the end spacer being held up as a check - still need to thread the holes and cut/trim the spacers apart. Maybe tomorrow on that part....