Author Topic: Back to Steam  (Read 64318 times)

Offline Robert Hornby

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Re: Back to Steam
« Reply #210 on: October 21, 2017, 09:28:40 PM »
Excellent Brian, I love the technique of making the cylinders and they do look great. :D :ThumbsUp:
Will you be adding anything to the outside of the cylinders?
Robert
Age and treachery will always overcome youth and skill

Offline Brian Rupnow

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Re: Back to Steam
« Reply #211 on: October 22, 2017, 12:51:36 AM »
No Robert--As this engine will run on compressed air and not steam, I am not worried about "heat loss" at the cylinders. I will polish the brass pieces and leave it at that.---Brian

Offline Brian Rupnow

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Re: Back to Steam
« Reply #212 on: October 22, 2017, 01:55:57 PM »
This will be the final "run in" of the engine, to let the pistons get well acquainted with the new cylinders. There is more information in the text part of the youtube video. That scraping noise you hear in the video isn't the engine. It's the side of that rather wonky big v-pulley scraping on the side of the workbench.
https://www.youtube.com/watch?v=UCVN3yoxvV0&feature=youtu.be

Online Jasonb

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Re: Back to Steam
« Reply #213 on: October 22, 2017, 04:11:18 PM »
So you are hopefull that the valves and eccentrics will all be free running straight off the machines?

Offline Brian Rupnow

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Re: Back to Steam
« Reply #214 on: October 22, 2017, 05:02:08 PM »
Yes. Hopeful---

Offline Brian Rupnow

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Re: Back to Steam
« Reply #215 on: October 22, 2017, 10:35:43 PM »
Here we are turning the ends of a steam chest between centers. One center is held in the 3 jaw chuck, one held in the tailstock chuck with a bit of grease on the tip to keep it from getting hot or burning off. The lathe dog is a machinists clamp with a 1/4" bolt screwed into the side of one jaw to transmit torque from the 3 jaw to the steam chest.

Offline scc

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Re: Back to Steam
« Reply #216 on: October 23, 2017, 11:36:44 AM »
What a cracking little engine, and beautifully made too. ...Following with interest :popcorn:       Terry

Offline Brian Rupnow

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Re: Back to Steam
« Reply #217 on: October 23, 2017, 08:12:45 PM »
The steam chests are still "in process". One is about 80% finished and is bolted in it's final position on the cylinder. The other steam chest is "Hot off the lathe" and I left the machinists clamp on it so you can get a better idea of how the 1/4" bolt screwed into one of the legs becomes the "drive dog" when it is set up in the lathe. The longest 5/16" diameter end will only be about 0.3" long when it is finished, but I have left it longer so I can grip it in my 3 jaw chuck on the lathe for when I go to put in the bore for the valve actuator linkage,

Offline Brian Rupnow

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Re: Back to Steam
« Reply #218 on: October 23, 2017, 09:59:27 PM »
Today I discovered the first error in the 3d cad model of this engine which I downloaded from GrabCad. The hole in the end of the steamchest where the rod enters is shown as being .093" diameter, instead of the .125" diameter which is necessary to get the rod thru the hole. Not a big deal, and caught before I actually put the hole in. Easy to correct. Whoever made this 3D model has done a terrific job on it. I'm wondering--If the hole in the gland nut is 0.125" diameter, should I perhaps open the hole a couple of thou. larger in the steamchest entrance? I have never had a lot of luck putting two holes in parts that thread together and expecting them to line up perfectly.
« Last Edit: October 23, 2017, 10:12:10 PM by Brian Rupnow »

Offline crueby

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Re: Back to Steam
« Reply #219 on: October 23, 2017, 10:29:56 PM »
On holes like that, where I am using a o-ring for the packing, I normally make the holes in both the steam chest and the packing nut a little over-size, runs much freer that way, and the ring does the sealing.

Offline Brian Rupnow

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Re: Back to Steam
« Reply #220 on: October 23, 2017, 11:54:35 PM »
Good idea, Crueby. I hadn't even thought of using an o-ring for packing. How much oversize do you make the holes?--About 0.010"?

Offline crueby

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Re: Back to Steam
« Reply #221 on: October 24, 2017, 01:12:47 AM »
Good idea, Crueby. I hadn't even thought of using an o-ring for packing. How much oversize do you make the holes?--About 0.010"?
Yeah, whatever the next drill size about that much bigger is. If you use a twist drill to make the packing opening rather than a boring bar, then the bottom of the hole is already tapered, which pushes the o-ring against the rod and faces nicely too.

Offline Brian Rupnow

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Re: Back to Steam
« Reply #222 on: October 24, 2017, 01:31:03 AM »
My drills go up in 0.015" increments. And that second steam chest marks the last of the "big" pieces. I still have a whole bunch of "little pieces" to make, but this has come together nicely and is starting to look like an engine.

Offline Steamer5

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Re: Back to Steam
« Reply #223 on: October 24, 2017, 04:24:33 AM »
Hi Brian
 Not being saying much but following along, coming along nicely! On the tail hole in the valve chest, it’s likely the 0.093 is correct, the valve nut is threaded so the tail end needs to be the root diameter of the thread so that it’s smooth for going in the support, also suggest that you put a flat, doesn’t need to be very big, along the top so it doesn’t turn into a piston & can relive any pressure from the blind hole.
Jo covered the how to on the valve chest nut issue, pretty much put the nut in the valve chest & finish them together......sure Jo will correct me if I’m wrong, quite likely as I’m doing a bunch of night shifts.

Cheers Kerrin
Get excited and make something!

Online Jasonb

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Re: Back to Steam
« Reply #224 on: October 24, 2017, 07:43:19 AM »
I usually ream the chest and nut on size eg 0.125" as the stainless stock for the valve rod is seldom spot on size and usually a thou or two below. If you think you will have problems with getting the two holes lined up cut the male thread on the gland nut a little deeper by tightening your die which will allow it a bit of lateral movement.

Even though you are running on air I would still put a small flat on the 3/32" end of the rod to avoid hydralic lock which you could still get with oil or a buildup of condensate from the compressor if you don't have a moisture trap.

Your nut should also have clearance to the bottom of the slot in the valve so the valve can lift off the portface slightly. Again more a steam thing but people may well build from your drawings and want to run on steam.

 

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