PM Research Engine Number 1

[gary.a.ayres]

But a cool item nonetheless.

You appear to have the admirable qualities of persistence and patience.

 

[mklotz]

If you ever run across a 4jaw for a small lathe, e.g., Unimat or Sherline, snap it up.  Make a stub for it and pop it into your 3jaw for small jobs like this.

[propforward]

But a cool item nonetheless.

You appear to have the admirable qualities of persistence and patience.

 

Thanks Gary, though I was starting to run out of both on this exercise.

Marv - great idea. I am now watching a few different small chucks, and I think I will try and pick one up before making the mating part to this. Frankly, I think the collet adapter approach I tried here is a great idea - but the part has to be precisely made. Mine wasn't nearly good enough, and it took me some rework to get it to function at all.

That said, improvements to techniques don't come without pushing yourself somewhat, so no regrets. I may well attempt to make another collet adapter to use for the mating part of this linkage, but for now I'll take a break from 3/16" square brass and make something else.

Anyway, some pics. The basic approach to this is simple enough - mill away two sides, drill the hole for the pin. Then I chose to shape the end by hand - I'm not very good at that kind of hand work, but for this part it worked well enough. Then cut off with some stock left, into the lathe, face to length, turn the chamfer, drill and tap the hole. Here are a few pics en route. I had to use my standard approach of "make it at least twice" before it came out "well enough". It's about 0.01" too short, but I think it will work. The tang is spot on though, in terms of length, thickness and hole position.













I need to try something else, so I think I will have a try at the eccentric or the piston next, before returning to the crankshaft.

Boy, there is still a long way to go on this.

[Flyboy Jim]

I finally got caught up on your build thread Stuart. It's coming along nicely. 

Jim

[gary.a.ayres]

Neat work Stuart.

Seems to me that when it comes to engine building there's always a long way to go...

[propforward]

Thanks chaps.

Had some fun turning the eccentric hub today. Simple enough, but turning offset features in the 4 jaw gives me a lot of pleasure for some reason. I always enjoy the first start up of the lathe and seeing the center point stationary with an obvious offset mass whirling around it. I don't know - it's the simple things I guess.

Anyway, for this, I cleaned up the ends of the supplied steel first, then transferred to the mill. Found center in the mill, offset the required .188", and center drilled the position of the bore.













I was pleased to find that after drilling and reaming the hole, a .375 pin would just slide in, squishing the air pocket as it did so, but that a .376 pin would not go in. 





That was a lot of fun. Not especially difficult, and all dimensions hit at this point.

next is to turn a groove in the OD for the eccentric follower to ride in. I made a start, but on the basis that I have very little experience grooving (other than my wicked moves on a saturday night), I have decided to practice this aspect on a piece of scrap first, because it would be a shame to ruin this part at this stage.

[Johnmcc69]

 
 Looking good Stuart!

 John

[gary.a.ayres]

Most satisfying.

And I'm sure your Saturday night clubbing (disco?) experience will stand you in good stead in the workshop.

Relax and swing...

[propforward]

"Well you can tell by the way I use my lathe
I'm an engine man, no time to talk.
Squealing loud and coolant warm, I've been kicked around
Since I was born

And now it's alright, it's okay
And you may look the other way
We can try to understand
The carbide inserts effect on man
Whether you're a turner or whether you're a miller
You're stayin' alive, stayin' alive
Feel the tool tip breakin' and everybody shakin'
And we're stayin' alive, stayin' alive
Ah, ha, ha, ha, stayin' alive, stayin' alive"

Sorry.

 

[Kim]

 
That's pretty good!  the Bee Gees should have gotten you to write their lyrics! 

Kim

[gary.a.ayres]

And then there's the line in the Thomson Twins song:

'...I know what it means to work hard on machines...'.

I offer this without comment other than to say that in my home shop the only machines I have are a metal lathe, a wood lathe, a drilling machine and a milling machine...

[propforward]

Well, I got my groove on, and this is where I am.





Made a few novice mistakes along the way, but recovered - didn't scrap the part.

Even managed to part it off, without too much drama.



Except for that blasted stub. But no matter, I left a little stock on the back face for some clean up, since I had a suspicion that parting off might not give me the final finish I want. I'll get there on that, but I know I can skim that face to a nice finish, so not too worried. Just trying to decide whether to make a little aluminum collar to hold it on the groove diameter, or just set it up in the mill and skim it there.

On balance, though it is more time consuming, I think I will make a little collar, because then I can chamfer the edges of the lips, hiding that error you can see in the picture. There I go making mountains out of molehills again.

[gary.a.ayres]

Nice work, and nothing wrong with setting a high standard for yourself and having the patience to work towards it.

[propforward]

Thanks Gary - always appreciate your input and encouragement.

Turns out making a little collar to hold the part was not a big deal, helped a lot by the fact I found this in the scrap bin.



Can't remember for the life of me what project that resulted from, but it just needed a little boring out to size.



And when all was said and done, the backside cleaned up a treat.





Still needs a little deburring and chamfering on the inside of the lips, but you know - overall - satisfied with this part, plus tried my hand at some new things. Win!

Now it's time to clean down the lathe, then a cocktail and get ready for thanksgiving tomorrow. 

[gary.a.ayres]