PM Research Engine Number 1

[propforward]

It is very satisfying to make a part that just fits properly into the mating part, without having to go back and fettle it. I’m hitting dimensions much more accurately now, and I have high hopes for a decent operating engine.

[propforward]

I started the day feeling cranky, but as I got on with things I started to feel groovy.

Oh what a barrel of laughs I am today.

Anyway, I had what I thought was a rock solid plan for finishing the crankshaft, so to that end, I popped it in the mill, to find center of the shafts, and spot the .75" offset for the crank diameter turning. Which worked great.



Small ER11 collets and a holder are jolly handy to have around for clearance issues.



A little jumping around. I decided to clean the outside of the webs to a radius while I still had the collet chuck set up.



Then cleaned the underside and removed the bridge.



I haven't been able to bring myself to check whether the thing has moved around yet.

But anyway - went to install in the 4 jaw, thinking I could hold on to one crank web and indicate the spot mark. But no go - the one shaft going into the chuck interferes with the chuck body, and I can't get it positioned right. So, I may have to make the jig that PM Research have in their plans after all.

But I didn't feel like doing that right now, so I decided to make the piston. A failry simple part really, just needing diligence on turning the diameter.

I turned diameter, then made a "sacrificial groove" on the end face, to check depth of the grooving tool, and set up the dial. Then made the grooves. This carbide grooving tool is really, really nice.



I set up a DTI to more accurately measure saddle movement.



This works so well, that I am clearly going to have to make a proper holder for it and use it routinely. Cheaper than a DRO, although more faffing about.

After grooving for a while, I cleaned up the face and drilled the 1/8" through hole. I wanted to do this in one set up, because it is important that the hole is very perpendicular to this face, as this is what locates the cylinder shaft - although really it's just the face that does that.



Parting is such sweet sorrow.

This was the best parting op I have ever done. The parted face ended up with a good surface finish. I could have parted to length - and probably will next time. First time using this tool.





Then flipped it round, faced off the little bit of clean up stock and counter bored the other side per print.





That was fun. Interesting change in surface finish on the face of the part in the last picture. Can't feel it with a fingernail - it's just from when I turned the coolant on part way through facing it. Lesson learned - perfectly fine, just looks weird. I can polish it out, but since it will be hidden in the cylinder I'm going to leave it as is.

[propforward]

Here are todays shed-nanigans. Basically, I took a rusty old lump of some sort of steel - no idea what alloy - I liberated it when it was thrown out at work about 12 years ago. Anyway, this became the basis for a holding jig for the crankshaft. There now follows pictures, but not much explanation. (Further research leads me to believe it is 4140 HT. Partly because of the yellow identifier colour one end, and because all the materials at that little firm came from McMaster Carr - I believe that's their identifier - could be wrong).







I like my rolly-cart, which is handy for holding up drawings close at each machine, as well as essential tools. Like the engineers universal adjusting tool (coarse version).







To the mill - and centering with the very fun centering indicator.















I tried it in the 3 jaw first - the design of the jig (slightly different to mine) comes from PM Research, and the idea is to use it this way to get the crank throw. It works well, I only ended up 0.003" off.

However, I never intended to use the 3 jaw (although let's face it, that would work fine), but I got it to 0.0005" in the 4 jaw.









That's as far as I got. I got the crank cleaned up, but now I need to take it to final diameter. But I ran out of time and energy today.

[crueby]

Nicely done!     Those co-ax indicators are super handy.

[propforward]

I love that co ax indicator. Bit of a luxury, because you can achieve the same with a lever type dial indicator, but it’s really fast to get accurately centered.

[propforward]

If I ever finish this engine and get it to run nicely on compressed air, then I’m going to be making serious use of this book that I just obtained. It’s an excellent book, has to be said.

[gary.a.ayres]

I started the day feeling cranky, but as I got on with things I started to feel groovy.

Oh what a barrel of laughs I am today.

Parting is such sweet sorrow.

Well, at least you're not the sort to make cutting remarks...

Great progress you have been making. I hadn't received any notifications for a while so I wondered if you were on 'pause' mode, but I must have just missed one (after which no more are forthcoming until you read the first one).

You are getting the urge to build a boiler... the K N Harris book is a great resource.

[propforward]

Thanks for checking in Gary! I always appreciate it when people comment.

I'm pleased with the progress - although I made a couple of errors on the crankshaft jig and wrecked a couple of HSS milling cutters. Nothing dangerous, just stupid approach, resulting in burned up cutter ends and hardened steel on the part. Had to change my approach a bit, but recovery went well and the jig is working nicely.

Yes - I'm pleased enough with the fit of the parts on this engine, that if it runs well on compressed air, then I'll kick off a boiler project. I got lucky on the book - only $15 lightly used, and it's an older genuine deition with nice clear plates and pictures in it. Bit of a treasure, almost has me wanting to protect it and get a rattier version. I also have some drawings coming from Reeves. Haven't decided what design boiler to make yet, just taking an interest for now. I may well model up whatever design I choose and do a full finite element analysis on it. I need the practice on that anyway.

[gary.a.ayres]

Am looking forward to seeing you develop a boiler!

[propforward]

Well, at least you're not the sort to make cutting remarks...

This didn't go unnoticed by the way. I just couldn't think of a decent riposte. I'm not feeling very sharp today. I need more of an edge.

[gary.a.ayres]

Me too. I was thinking of taking a walk to see if it would give me some inspiration, but I just looked out the window and it's rough out, so best just to bring it to a finish now.

[propforward]

I can't follow that! I guess I'd better stick to making this engine. Crankshaft finished, and made a start on the connecting rod.

[gary.a.ayres]

Very nice work on that crankshaft, Stuart. The conrod should be fun!

It's starting to look like an engine now...

[Jo]

Hi Stuart,

May I suggest you mount the connecting rod on top of a piece of scrap (jig) so that when you bore through the two ends you don't mark your mill's table   

Jo

[propforward]

Thanks Gary.

Yes Jo - you may suggest that, although at this stage I'm only flattening off the sides, I wasn't planning to drill either hole yet. I'm going to drill the big end bosses next on an angle plate, before returning to the table to drill the little end hole, and then split the big end, and get ready for drilling and reaming that.

To be honest, I think I'm already making a bit more of a meal of this part than I needed to. I could have drilled the little end in that first set up, but at the time I wanted to register the big end against the table for best parallelism. Probably a bit over the top of an approach, and more set ups than needed now that I step back and look at it again. Oh well.

Thanks for looking in and commenting though, much appreciated.