Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines
Builds, Repairs, Show Your Machines! => Technical Tips, Builds, and Help => Topic started by: komet163b on September 18, 2019, 11:27:17 am
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Aye, Aye. I already drew a diagram to scale and
made a paper pressing of he ports. Now that the shoe
is loose we can review the port/shoe arrangement to
determine if any adjustments to the ports or shoe are
needed. Photos and specs soon.
More pressing....the rod that drives the shoe is steel
and must have been left wet for an eternity leading to
corrosion of the threads that held the keeper-nut.
The keeper nut is a ground down nut, so that is BS too.
It all still works but I think the lifetime for running is
low. I am making plans for a possible replacement
P.S. The eccentric throw is 1/8". Paltry if you ask me
Thanks for the advice and the time you took to give it,
Wayne
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Right I want you to measure the amount of movement in the eccentric from end to end .
Then remove the steam chest.
I then want you to make a card board template exactly the same as the port block/shoe
ie a square with the center square cut out.
Then place the cardboard template on the block in exactly the center over the ports
You should only see the center port .
Move cardboard to right exactly half of your eccentric throw measurement.
Take photo then move it to the left your total eccentric throw take another photo
Show us the results .
“ do not fiddle with the port slots yet “
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Well, now I've gone and done it.
The rod going into the shoe would
not budge when I fiddled with it but
it apparently loosened after some
running on air. I was checking the
timing, had the eccentric-rod off
and noticed the shoe-rod was loose.
The next thing I knew it was in my hand
and my BP went up. I now could see
threads on the rod and tried to get it
back into the shoe, but, so far no luck.
I may have to reopen the valve chest.
If I do I may clean up the ports if it makes
sense. Sometimes you are forced to take
a step back to get ahead.
More grist for the mill,
Wayne
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Personally i think it is a design fault .
The valve should float but i think the biggest issue is the ports in the cylinder block .
No amount of work by you will fix it properly.
I think the two, inlet ports are to far from centre..
Take the non floating valve off the spindle
Place it in place on the ports when it is moved the same distance as the eccentric will move it
One port should be exposed and at the same time the recces in valve should cover center port and the other port.
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Well, here we go again.
Why can't things be simple and work as they should...
Well, it is sort of ok. I sealed up the valve chest with
the same sealer your grandpa would have used,
Indian Head Gasket Shellac. I even spoke with
a tech rep and he thought it was a good idea. I've
added before/after photos.
I hooked it up to my usual air source and it just
would not go. I then took it out to my garage
compressor and it took off - but at a much higher
pressure(?) than need be. There are no leaks and
it turns over reasonably well by hand, so I think it
might have to do with the valve and ports. They
looked a bit hinky to me and I was sorely tempted
to do a bit of grinding work to make them right
but thought I should give it a chance as it was. So...
IT DOES (slowly) RUN!
Where do I go from here?
Wayne
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I started using Never-Seez when I work on the boilers at
school and I still use it. The gaskets never stick no matter
how long they on the boiler or traps.
https://neverseizeproducts.com/never-seez-nsb-4-regular-grade-lubricant-anti-seize-4-oz/
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Sounds like a plan. Keep us updated on the progress.
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Your advice sounds good. I'll look into the Loctite
line of products.
I'll check the sealant/adhesives aisle of my local
hardware store. I'll also check to see if there
are any lapidary adhesives that would be apropos.
Thankfully, the problem deposits look to have been
just surface deposits and there was no pitting.
I'm ready to go.
Wayne
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One piece...guess that limits you. I'm not sure what sealant, I've never used any on a steam engine. On mc engines, I use HondaBond, or Loctite grey case sealant(I can't remember the number). It is good stuff.
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The valve shoe is, so to speak, part of the
valve chest. If the chest is moved away from
the valve-seat by the thickness of a gasket the
shoe will be moved that far away from the sealing
surfaces. Not the way I would have done it. I
would have had a separate cover for the valve
chest assembly. Therefore, either use a thin smear
sealant or, if a gasket is needed, a very thin one.
I vote for sealant only, as originally done.
And when it works.....distilled water only, and blow it
out w/air after running. The only way to do it.
Thanks for the comments....give me more.
Wayne
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Gasket material wouldn't change the relationship of the valve to the ports, it would only insure no steam leaks.
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Yes, exactly, it is the admission steam pressure that keeps the D-valve seated. That one has some rather rough looking machining, especially on the exhaust "pocket", but I've seen worse that still ran just fine, so if it works well, I'd leave it.
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I just finished a first pass at cleaning it up.
I used a non-abrasive scrub pad glued to a
narrow stick, tested it on some scrap brass
to ensure it doesn't abrade/wear and ran it
across the sealing surfaces. Seems pretty
clean and smooth - check out the pix, one
with flash and one without.
As for the gasket surface, I'd like to try it
as I found it - no gasket. I really do not
want to force the shoe any farther away
from the valve-seat. So, any suggestions
for a sealer? Preferably a sealer that can
be dissolved away if I need to open it up
again. I just want to seal it not glue it.
One operational question. What holds the
valve-shoe against the valve-seat? Nothing?
It seems a bit....illogical. All I can imagine is
that the steam pressure forces it against the
seat. Is this so?
Thank You,
Wayne
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I would be careful using lime away. Vinegar/water mix is less harsh. If you intend to use gaskets, and if the screws are long enough i surely would, then we're it me I would face the valve block anyway...flat plate and some wet Emory with light circular motion. Give a good clean sealing surface.
With the valve chest that crusty, I would go ahead and take the whole thing down. There are plenty of folks to help if you run into problems and it really needs it or you'll just be doing it later.
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I agree. The question is, how to clean it up.
Is there a chemical solution like lime-away
that removes scale build-up but will not affect
the brass? Or do I need to use a scotch-brite
pad? I hesitate to go to any kind of abrasives
such as 400grit wet/dry. And, when I get past
that, what to use for a sealant is the question.
There seemed to be no gasket before, so, any
suggestions?
Thanks,
Wayne
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Yep I'd guess that would definitely keep it from sealing. Looks like some maintenance is in order.
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Well, I took the steam-chest valve-cover off.
A bit of effort with the fingers and it loosened.
Off it came. Not much in the way of gasket.
The sliding surface looks a bit...rusty. The only
iron is in the studs and the surfaces in question
are not iron. So, I suspect they are just mineral
deposits left there. These deposits on the
sealing surfaces may be the problem - lack of a
proper seal. I've added a photo of the miscreants.
The grid is 3/4".
Any suggestions would be appreciated. Hopefully,
the analysis is correct and the fix is easy.
Thank You,
Wayne
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Well done Wayne, that's definitely one of the nicer home-builds I've seen 8) Would love to see a video ;)
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It is nice looking. I paid a modest price for it to the
owner, the grandson of the machinist who made it in
1929. When I get it running I'll put a video out there
as a thank-you to him and the community.
I'll take your advice re the video to watch and the timing.
If that seems to not be the problem, then off with the
valve chest. Photos at each stage of disassembly, of course.
As to the burner...I've seen burners for yard work and
I'm still looking. Any specific suggestions? The flame
has to be horizontal as the flue is. Would the flame from
a propane torch be too fine/pointed to use?
Anyway, I steamed up my Empire 43 for fun yesterday.
The cartridge heater I put in it is only 200 watts so it
doesn't run any faster than a couple hundred rpm, but
it will run forever. Chug, chug, chug.
Thanks for the reply,
Wayne
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Crank should be at 90° top dead center with shoe just staring to uncover port. Centered between inlet and exhaust of course.
Take a peek at Keith Appleton's YouTube video on timing a steam engine. And I would just go ahead and bite the bullet and open up the valve chest, to replace gaskets and verify there isn't a dead bug or dirt dauber nest in it.
Can't help with the burner, I've seen them before but don't know much about them. I think I might try to find a blowtorch burner new for it.
It is a nice looking piece of work. Can't wait to see what you do with it.
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I just came into a homebuilt 1929 engine/boiler combo.
I've added some pix to illustrate.
There are two areas of concern - the boiler and engine.
I'll start with the boiler.
The boiler has horizontal flue with 14 cross-tubes forming
seven 'X's' down its length. It did have a super-heating
loop but it was not very 'tasty' so I removed it for simplicity.
I can always put it back later. The boiler SV is a miniature
of the real industrial ones but is frozen - I believe it should
be able to come apart but it is stuck so to work on that. No
SV no steam. The part I'm not sure about is the heater that
came with it. I've included photos. I know part of it is a
blowtorch style burner, but the box (homemade) has no way
to fill it. I like some puzzles but what kind of fuel did this take?
I'm just curious as I'm guessing readers will suggest I go with
a modern burner. Any suggestions? I'm working on figuring
a way to pressure-test the boiler. I need to speak with my
old-school plumber on this one.
The engine has a valve problem (timing?) as the air flows right
thru to the exhaust when testing regardless of the position of
the valve shoe in the steam-chest. Either the timing is wrong
or the shoe is not properly seated, or worse, poorly machined.
One big question....when should the shoe uncover the inlet port,
before, at, or just after TDC? I'd like to avoid opening it up.
Thanks for any advice offered,
Wayne