Author Topic: PMR 7 Twin Cylinder Steam Engine  (Read 20158 times)

Offline zeeprogrammer

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #285 on: May 03, 2018, 02:33:05 PM »
Thanks Tony. One of the tests I had made was to remove the gasket. So far things point to the cross head but I'll let everyone know what I find.

Thanks Simon and Jo. I'm not sure why the DRO on the lathe is being discussed unless this came from a much earlier post. I agree that (for me anyway) a DRO is not a 'need' for the lathe. I was most interested in the tail stock but I'm thinking it won't solve my troubles. I've found that when drilling, the tail stock tends to push back (slips) a bit until its stop fully engages. I don't know if this is unusual or not and a tail stock DRO won't fix that. I've taken to using tape on drill bits to monitor depth but this doesn't work all that well. Chips tend to push the tape. As for the markings on the tail stock quill...slippage makes that somewhat useless and I have trouble reading the marks anyway.

Any thoughts on preventing the tail stock slip? If I can guarantee it doesn't move then I'd go for a DRO.

Going back to the mill DRO...am I correct in believing I don't need to worry about backlash?

As a side note, the mill has a built-in DRO for the quill. Very hard to read though. I have to stoop and it's rather dim (but that may be a weak battery).
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Online sco

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #286 on: May 03, 2018, 02:36:18 PM »
The DRO measures the table actual movement - so you can completely forget about backlash.  You just wind the wheels and watch the digits - you'll never look at the dials again!

Simon.
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Online Jasonb

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #287 on: May 03, 2018, 02:51:59 PM »
Do your tailstock up tighter, that will stop it slipping ;) make sure there is no dirt under the tailstock or a bit of paint. Also the "plate" that runs below the bed may have a burr. Also the nut under the plate may want tightening as you could be running out of movement on the levers cam

Back to the cross head issue , when making an engine I often turn a small point onto the piston rod and this can be used to mark the correct location for the hole in the crosshead

Offline zeeprogrammer

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #288 on: May 03, 2018, 04:06:17 PM »
Thanks Simon. Yes...the DROs are a joy.

Do your tailstock up tighter, that will stop it slipping ;) make sure there is no dirt under the tailstock or a bit of paint. Also the "plate" that runs below the bed may have a burr. Also the nut under the plate may want tightening as you could be running out of movement on the levers cam
Back to the cross head issue , when making an engine I often turn a small point onto the piston rod and this can be used to mark the correct location for the hole in the crosshead

Thanks Jason. I'll take a look at the tail stock. Sounds like it shouldn't be slipping at all. Nice tip on the piston rod. (No pun intended.)
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Online Kim

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #289 on: May 03, 2018, 04:52:37 PM »
Just a note on the DRO topic (which I know you're not covering here :)).  I have a DRO on my lathe and I wouldn't be without it, regardless of what others say.  Sure, there are other things that might be higher priority.  But for me, a DRO is a plus.  Really makes it more fun to use.  And isn't that what its all about?

I agree with Jason, your tail stock shouldn't move when tightened down.  I find that over time, the nut on the bottom of the clamping plate will loosen and I have to tighten it up to get a good lock with the cam, just as Jason said.  (Guess I could have just said +1 for what Jason said!)

Kim

Offline Tennessee Whiskey

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #290 on: May 03, 2018, 05:31:49 PM »
First side is looking good. Not that Iím really qualified, but, put on the optic visor and get eyeballs to eyeball with the other side and watch it with the patience of a world class chess player as you slowly turn it over by hand. With enough patience, Iíd bet an RC Cola and a Moon Pie that you will see where itís actually binding. Remember Caddy Shack?  Be the engine  8) :facepalm:

Cletus

Online crueby

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #291 on: May 03, 2018, 05:58:10 PM »
First side is looking good. Not that Iím really qualified, but, put on the optic visor and get eyeballs to eyeball with the other side and watch it with the patience of a world class chess player as you slowly turn it over by hand. With enough patience, Iíd bet an RC Cola and a Moon Pie that you will see where itís actually binding. Remember Caddy Shack?  Be the engine  8) :facepalm:

Cletus
Good tip. Sometimes you can see the burnish marks where it sticks.
See the crosshead, be the crosshead...

Offline mklotz

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #292 on: May 03, 2018, 06:23:28 PM »

  I find that over time, the nut on the bottom of the clamping plate will loosen and I have to tighten it up to get a good lock with the cam

When I first bought my lathe, I had the same problem.  I added a lock nut to the bolt and since then haven't had a problem.
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Offline Tennessee Whiskey

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #293 on: May 03, 2018, 07:56:17 PM »
Now onto the tail stock issue: Iím beginning to sound like Mr. Pete  :lolb:. As mentioned by previous posters; nip up the nut under the lathe bed. My Grizzly lathe has to be farted with after a few passes to make it lock up. On the other hand; the one on the old Ď44 Monarch 10EE, locks up with a knats breath  :shrug: :lolb:

Cletus

Offline zeeprogrammer

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #294 on: May 03, 2018, 11:39:50 PM »
Got the other cylinder running. But there's problems.


Takes a lot of pressure. Some of which is due to leaks at the set screws used for plugs. I haven't sealed them nor the pipe nipples.
Bigger problem turns out not to be the cross head but something not true between the piston rod, gland nut, and head cover.
A bit of cleaning and reaming helped a lot but I fear it would take remaking some cast parts to really get it right.
Doing anymore and it will be more leaky.

You can tell it's pretty tight when I turn off the air. The engine stops immediately.

I'll get it best I can but I won't go down the road of ordering replacement cast parts.

A big challenge will be soldering the tube between the pipe elbow and pipe T. Once that is done, disassembly/assembly is more difficult.
I'm going to soft solder it. I have a large soldering gun (not for electronics) and wonder if that will be enough.

I should feel pretty  :pinkelephant: but not quite. Still...I think my best work thus far so that's something.
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Offline Tennessee Whiskey

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #295 on: May 03, 2018, 11:47:47 PM »
So, both sides are chooching, and although it reminds me of high school night of romance  :lolb:, Now you just gotta get her calmed down. Itís all in the ďtuning and fettlingĒ now  :popcorn: :ThumbsUp:.  Congratulations Zee.

Cletus

Offline Craig DeShong

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #296 on: May 04, 2018, 12:16:35 AM »
It's running  :cheers:

Some more fine tuning and it can only run better.  Look at all you've learned.   No doubt your next project will go better.
Craig

Offline b.lindsey

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #297 on: May 04, 2018, 12:57:36 AM »
This is still progress Zee. Just keep running it in for a while with plenty of oil and it may surprise you.

Bill

Offline zeeprogrammer

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #298 on: May 04, 2018, 01:12:56 AM »
Thanks Eric.
Thanks Craig. Next project 'always' goes better.  ;D
Thanks Bill.

I think, rather than soldering the tube in now, I'll rig up a manifold to drive both cylinders at the same time until I have it running better and adjusted.

As I mentioned, once the tube is soldered in place, you have to remove both cylinders if you're going to remove one.

Still feeling optimistic. And even if this is a 'bust' (in the sense that it's not nearly as good as I want), I'm pretty happy to have gotten here.
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Offline zeeprogrammer

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #299 on: May 04, 2018, 01:33:20 AM »
This is what I'm thinking. That should make adjusting/setting easier.

[EDIT] Now I'm wondering where and why I got that. Might be one of those 'might be useful things' at the time.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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