Author Topic: PM Research Engine Number 1  (Read 32158 times)

Offline propforward

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Re: PM Research Engine Number 1
« Reply #300 on: August 07, 2021, 09:37:31 PM »
Thank you all! Yes - very pleased.  :cartwheel:

I would like it to run a bit slower, but I think it has some air leakage past the valve in the steam chest. I made the slots in the cylinder too wide and the valve only just covers them. I have a feeling that if I made a new, wider valve that might help it run even slower. Don't know that I will do that. I think I would rather paint this and move on to a new project, and try and make a more refined engine. All that aside, I'm nevertheless very pleased with this. Thank you all for your kind words.
Stuart

Forging ahead regardless.

Offline bent

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Re: PM Research Engine Number 1
« Reply #301 on: August 09, 2021, 09:34:10 PM »
Nice job overall, propforward.  :cheers:

Online Kim

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Re: PM Research Engine Number 1
« Reply #302 on: August 11, 2021, 01:27:52 AM »
Late to the party here, but I've been out without internet for most of the last week (if you can believe it!  :o).

Great runner, Stuart!  And great video.
You should feel quite proud of that accomplishment!

Kim

Offline propforward

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Re: PM Research Engine Number 1
« Reply #303 on: August 11, 2021, 02:09:40 AM »
Thanks Kim and bent - very much appreciated. Always a good feeling when an engine runs.

Kim, glad your internet is back! First world problem perhaps, but aggravating nonetheless.

Iím going to strip the engine for painting this weekend, and I think I will make a new valve out of bar stock, and see if I can get it to run just a little slower. Not a big deal but that would be rewarding.

Iím thinking RAF roundel blue should look decent.
Stuart

Forging ahead regardless.

Online Kim

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Re: PM Research Engine Number 1
« Reply #304 on: August 11, 2021, 05:41:18 AM »
Kim, glad your internet is back! First world problem perhaps, but aggravating nonetheless.
Well, I was actually out camping and there was no cell service, thus, no internet.  So, don't feel too sorry for me!  I had a great time :)

Iím thinking RAF roundel blue should look decent.
Sounds like a great color to me!  :ThumbsUp:

Kim

Online MJM460

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Re: PM Research Engine Number 1
« Reply #305 on: August 11, 2021, 11:55:21 AM »
Hi Stewart, a great looking engine will look even better painted. 

Good idea to make that new valve while the paint is drying.  Apart from the width, it might be worth having a good look at the length ass well, just to make sure it is correct for the actual distance between the port edges.

It is probably ok, but I know I used the milling cutter I had for the Bolton engine.  This required a corresponding adjustment to the valve length to get correct lap.  Might as well make it as few times as possible.

MJM460



The more I learn, the more I find that I still have to learn!

Offline propforward

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Re: PM Research Engine Number 1
« Reply #306 on: August 11, 2021, 01:30:23 PM »
That's a solid point, and one I hadn't thought of. I'll measure the port sizes and spacings when I have it apart and correct it as needed. If I make it a bit long I can always shave it down -  they still haven't invented a reverse milling cutter that puts the metal back when going too short.
Stuart

Forging ahead regardless.

Offline Jo

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Re: PM Research Engine Number 1
« Reply #307 on: August 11, 2021, 05:01:17 PM »
-  they still haven't invented a reverse milling cutter that puts the metal back when going too short.

You silver solder a piece of bronze on the underside of the valve across in the over length end of the pocket and re-machine the pocket to the correct dimension  ;)  :-X

Jo
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Offline propforward

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Re: PM Research Engine Number 1
« Reply #308 on: August 11, 2021, 05:07:04 PM »
Ah I may not have explained my error correctly. The problem is that the ports in the steam chest are too wide, almost coincidentally wide as the valve casting. That said, your idea of silver soldering extra material on could still work, by adding strips to the edge of the valve. I would get to use a blow torch that way. I would have to ensure the joint was fully filled, and then do a light skim to get everything properly flat but potentially could work.
Stuart

Forging ahead regardless.

Offline propforward

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Re: PM Research Engine Number 1
« Reply #309 on: August 11, 2021, 05:45:30 PM »
I might actually try that, because if nothing else it would be an interesting exercise. I also just bought some silicon bronze TIG filler rod - I may have a try at building up the edge and see if I can recover that way - again it will be all for the fun and experience of it - it's kind of no loss at this point. Making a new valve from stock should not be that difficult if I destroy the current valve with my Machiavellian schemes. The valve is one of the few parts I managed to make to print, so I should be able to make another one. :D
Stuart

Forging ahead regardless.

Online MJM460

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Re: PM Research Engine Number 1
« Reply #310 on: August 12, 2021, 10:52:59 AM »
Hi Stewart, building up the valve sounds like a lot of work that will not save you anything of what is required to re-machine the valve.  Much easier to just start from a piece of bronze.

I did manage to make the valve for the Bolton from the casting supplied but two previous slide valve engines I just made the valve from bronze bar.

However, building up the valve might be a useful skill to have for the inevitable future slip up on a larger part on which you have spent a large number of hours before the slip, or one much more expensive to obtain replacement part or material.

MJM460


The more I learn, the more I find that I still have to learn!

Offline propforward

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Re: PM Research Engine Number 1
« Reply #311 on: August 12, 2021, 01:25:01 PM »
You're right on all counts - building up the edge is not really the best solution, only something to try for the interest factor. Most likely scenario is that I will blow a big hole in the part if I try it, but since I'm basically on a path of making a new part, the bit of time playing with the arc to see what happens is more for interest factor than anything else, plus the possibilities of future repairs on more appropriate parts.
Stuart

Forging ahead regardless.

Offline MMan

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Re: PM Research Engine Number 1
« Reply #312 on: August 12, 2021, 01:40:23 PM »
If you do try it I would be interested to know how you do. (given it being a small thing, might make sense to clamp to a heat sink like a copper bar first)

Martin.

Offline propforward

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Re: PM Research Engine Number 1
« Reply #313 on: August 12, 2021, 01:56:31 PM »
It's a research project now!

That's it, I'm doing it. Look for an update - whatever the result - on saturday evening Minnesota time.

Disclaimer - I have about 4 hours of hood time to my name. Don't expect too much.  :ROFL:

Good point on the heat sink, I'd say that's a must.  :ThumbsUp:
Stuart

Forging ahead regardless.

Online crueby

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Re: PM Research Engine Number 1
« Reply #314 on: August 12, 2021, 04:06:11 PM »
Will be interesting to see how that goes. Goes well, or goes through the side and out to the scrap bin!

For the air leakage issue in general, be sure that there is enough 'slop' in the slots to just allow the valve to move on the valve rod and the adjusting nut - if it binds on either, it wont be able to pivot as needed and seat properly on the valve face. You want it just loose enough to be able to slide off the rod/nut, but not so loose that it rattles around. Also, did you lap the faces a bit to allow a good seal? 

Even if one of those things is the real issue, the fattening up of the valve is still a very worthwhile experiment.
 :popcorn: :popcorn: :popcorn: