PM Research Engine Number 1

[crueby]

Slick little fixture, great progress.   

[Flyboy Jim]

Like Dave said..........a miniature 4 jaw chuck. I'm definitely going to file that one away. 

Jim

[propforward]

  Thank you all, I do enjoy knowing you are looking in. Quite looking forward to making a better version of this mini chuck and making the next gland.

[samc88]

Nice work, I like your fixture, I never would have thought of doing it that way

[propforward]

Thank you. I'm chuffed with my little 4 jaw. V2 will be even better.

In the meantime, I made a start on some test assembly.



Very pleased to find that I can turn the crank over with my fingers, and the piston rod slides nicely in and out of the inboard head. Very, very pleased with this. Just need to stay the course now - it's finally looking kinda sorta like an engine.

[Flyboy Jim]

Looking good Stuart. 

Have you figured out what the purpose of that 1" long white piece of material is. I think it has something to do with the packing for the gland on the Inner Head. I haven't put any packing there on my PMR #5 yet.

Jim

[propforward]

Thanks Jim!

Yes that 1” strip is teflon and is packing material for the glands. I saw someone actually roll a piece of it flatter before installing it. Seemed to help get it in place. I still have to make the inboard head gland, but I’ll be keen to get that done now.

[propforward]

Well, a little more progress. I made another holding fixture for the cylinder gland. This time I got the sequence right, and drilled and tapped the set screw holes before boring / drilling. I also put them in at a slight angle (about 1°) so that when tightening on the part, they force it down into the fixture. That was the idea anyway, and it seems to have worked.

The bore was made to tightly fit the largest diameter of the gland, to help hold it concentric to the center axis.









I did have an oops. Tool dug in - I must have tried to take too much off.



I t dug into the part and made it look ugly - but happily there was a fair bit of stock still to come off, so it cleaned up OK.





Off to the mill - centered using a gauge pin,



then rotated the part back and forth until a gauge pin looked even on both ears, and then drilled the holes.





Rotten finish on the front. It buffed up OK though.

Then I spent a bunch of time ruining some 1/8" stainless and brass rods, as I realized I didn't know enough about cutting male threads. A bunch of research, reading and some test runs later, and I'm about ready to re make those parts. So when I do, I'll post pictures.

That's it for now though.

[gary.a.ayres]

Nice work Stuart.
These mini-chucks of yours are an excellent idea..
The engine as assembled so far looks very handsome.

[derekwarner]

EPPT...... ...

....'excellent practical pictorial tutorial' in achieving rigidity and sound accuracy .....thanks for sharing Stuart....

A real help for newer players ...also plants the seed for other applications

[Some 55 years ago, I commenced a Fitting & Machining Apprenticeship...during a 6 month Term along this 4 year path, I was assigned to work under the supervision of a Grumpy  Scottsman  .......he spent 1/2 of his time designing and making Jigs of all types to achieve his level of component accuracy and repeatability] .......

The Grumpyness was only a ploy...as his quest was to impart knowledge and the need to think, then ask if you were unsure......

Derek

[propforward]

Thank you both for your very kind comments!

Derek, your grumpy Scot sounds like a fine fellow in fact. I've known a couple of folks like that - bit of a facade up front but incredibly helpful and knowledgeable.

It has been a bit since I had time to do any work on the engine, what with work and having to finish some other projects.

I had been working on a follow rest system for supporting small diameter shafts for turning and single point threading. It was way too complicated, and a complete failure. Based on something I saw Joe Pie demonstrate on youtube, and also on a thread on this very forum, I modified the follow rest and made it much simpler, and a lot more effective.

Essentially, I am just using my lathe follow rest, but I had made a new adjusting shaft and a bracket for it. The original idea was to use a couple of very small ball bearings to support the shaft.

In the end though, it's easier to bolt a piece of material (in this case a piece of phenolic) to the bracket, and just use an end mill in the chuck to drill a hole in situ, so that the support is perfectly centered.





It's then very easy to position the cutting tool close to the support for whatever work you need to do.



I used the "upside down tool" approach for single point threading, so that the cutting tool moves away from the headstock.



And it works a treat.





So I'm well pleased with that - no need for expensive dies for cutting small threads. Just as well, because the cheap dies are awful, I have had no luck with them at all - a waste of money. But this follow rest approach works really well.

[Kim]

That's a pretty slick little follower rest!  And easy to make whatever size you need too

Kim

[EricB]

Brilliant follower rest mod! 

Eric

[propforward]

Thank you - yes - very happy with this.

Shame I went and trashed my brass eccentric rod during test assembly. 

Never mind - quick enough to make another one now. 

[gary.a.ayres]

Very nifty arrangement, and it resulted in a tidy job!

Commiserations on the mishap, but it sounds like you'll get over it quickly.