Author Topic: Steam Tractor 3/4" (Rudy K)  (Read 174115 times)

Offline fumopuc

  • Full Member
  • ****
  • Posts: 2397
  • Munich, Germany, EU
Re: Steam Tractor 3/4" (Rudy K)
« Reply #1020 on: May 10, 2018, 07:37:47 AM »
Hi Kim,
may be you can find an American source for this type of valve balls.
https://www.bengs-modellbau.de/en/material/seals/157/grafi-sil-valve-balls
Perhaps this will solve your problem.
A more complicated but sure safe way is an other design of the ball seat, not easy to machine because of a self made tool for this.
See my picture below.
Left side is the worth way to do it.
Middle is better.
Right side is the best way to do it for a stainless steel ball.
 
Kind Regards
Achim

Offline zeeprogrammer

  • Full Member
  • *****
  • Posts: 6375
  • West Chester, PA, USA
Re: Steam Tractor 3/4" (Rudy K)
« Reply #1021 on: May 10, 2018, 12:15:57 PM »
Hi Kim, not to interfere...I had the same problem with the 0-4-0 British locomotive I'd made.
The valve ball in Achim's 3rd picture was what was wanted.
I took a twist drill and ground the tip off to that shape.
Something like this...(left is normal drill bit, right is ground down)
| |    | |
| |    | |
| |    | /
| |    /
\ /

But with the slash at a shallower (desired) angle.
I'm thinking (at the size I used) the drill bit was a bit too flexible and/or wobbled.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline steamboatmodel

  • Full Member
  • ****
  • Posts: 150
Re: Steam Tractor 3/4" (Rudy K)
« Reply #1022 on: May 10, 2018, 02:24:01 PM »
I made some check valves at one time where the seat wad on a screwed in insert. To get the ball to seat you took it and the valve seat and rolled the ball around with the seat on top of it on a couple of sheet of newspaper. The ink and paper fibers got picked up by the ball and wore a seal on the seat. Washed everything off installed it and it worked.
Gerald.
Be wary of strong drink. It can make you shoot at tax collectors--and miss. Lazarus Long

Offline Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3723
  • Portland, Oregon, USA
Re: Steam Tractor 3/4" (Rudy K)
« Reply #1023 on: May 10, 2018, 03:39:23 PM »
Hi Kim,
may be you can find an American source for this type of valve balls.
https://www.bengs-modellbau.de/en/material/seals/157/grafi-sil-valve-balls
Perhaps this will solve your problem.
A more complicated but sure safe way is an other design of the ball seat, not easy to machine because of a self made tool for this.
See my picture below.
Left side is the worst way to do it.
Middle is better.
Right side is the best way to do it for a stainless steel ball.

Thanks Achim!  This is a great picture of exactly what I am experiencing.  I'm certain I currently have the "worst" seat shown in your diagram (the first one). The D bit should give me the third one.



The input ball seat is of the middle type and seems to be holding quite well.

Those valve balls look great!  I'll have to dig around and see if I can find anything available locally.  Though I ought to be able to get a stainless steel ball to work just fine, since many people have proven it can be done! :)

Thanks,
Kim

Offline Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3723
  • Portland, Oregon, USA
Re: Steam Tractor 3/4" (Rudy K)
« Reply #1024 on: May 10, 2018, 03:41:01 PM »
Hi Kim, not to interfere...I had the same problem with the 0-4-0 British locomotive I'd made.
The valve ball in Achim's 3rd picture was what was wanted.
I took a twist drill and ground the tip off to that shape.
Something like this...(left is normal drill bit, right is ground down)
| |    | |
| |    | |
| |    | /
| |    /
\ /

But with the slash at a shallower (desired) angle.
I'm thinking (at the size I used) the drill bit was a bit too flexible and/or wobbled.

Nice ASCII art Zee!  ;)
Yes, I see what you're saying and I think that would give the same outcome as the D-bit I'm trying to make - it will have a 15o taper on the bottom, resulting in the third picture.

Thanks,
Kim

Offline Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3723
  • Portland, Oregon, USA
Re: Steam Tractor 3/4" (Rudy K)
« Reply #1025 on: May 10, 2018, 03:42:42 PM »
I made some check valves at one time where the seat wad on a screwed in insert. To get the ball to seat you took it and the valve seat and rolled the ball around with the seat on top of it on a couple of sheet of newspaper. The ink and paper fibers got picked up by the ball and wore a seal on the seat. Washed everything off installed it and it worked.
Gerald.

That's a very interesting process!  If I get to trying to lap a good seal, I will give this method a try too.  Though it could be difficult in this situation since the seat is at the bottom of a narrow hole.  Guess that's why the made the seats as screw-in inserts :)

Thanks Gerald,
Kim

Offline Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3723
  • Portland, Oregon, USA
Re: Steam Tractor 3/4" (Rudy K)
« Reply #1026 on: May 10, 2018, 08:20:54 PM »
I started by re-making the D-bit. Turned a length of 1/4" W-1 to size, then on the mill, I angled the end to 15o.


Then cut the bit width down to ~51% of the diameter.


Then I round a bit of a relief on the other side.


And heat treated then tempered it. Here’s the final picture with the melted one on the left, and the new one on the right.


I wanted to see if I could take before and after shots to see how much better this was.  So, here’s my try at the “Before”, looking down to the ball seat in the pump casting:


I lined it up using a pin gauge in the mill.


Then put in the D-bit and carefully made the hole about 25 -30 thousandths deeper.


And here’s the ‘After’ shot. Definitely much cleaner.


Then, I gave one of the bearings a solid THUMP to make the seat, and here’s wat it looked like.  You can see a nice thin seat all around the hole.  So I was very hopefully that this would work.


But alas, it didn’t.  No different than before.  I even tried re-thwacking it to make a ‘better’ seat, and tried different balls, but to no avail.  Same results, still won’t hold any pressure.  :wallbang:

So now I wonder if my hole is every so slightly out of round. Though the picture above makes it look pretty round.  Or maybe that little bit of chatter you can see has caused the issue?

I’m baffled.  I could try lapping, but I don’t have anything to do that with (no abrasive paste or anything) and it doesn’t seem like it should be necessary.  I could try the newsprint thing, but the hole is too deep to make that option really feasible.

At this point, I may just go with an external check valve.  I wonder if the Whack-a-bearing approach only works in Brass?  Maybe Bronze is too hard?  Porous?  Brittle?  I dunno. There’s got to be an explanation, but I’m ready to move on I think.

And that’s the news from the shop.  As Cletus would say, "Tell everybody, hey."
Kim
« Last Edit: May 10, 2018, 08:30:31 PM by Kim »

Offline 10KPete

  • Full Member
  • ****
  • Posts: 1565
  • Nordland, WA, USA
Re: Steam Tractor 3/4" (Rudy K)
« Reply #1027 on: May 10, 2018, 09:45:44 PM »
The hole must be round and have a very good finish, like the surface you just cut. Other wise any 'defect' in the hole will also be in the 'sharp edge'.

Try reaming the smaller hole a few thou to make the hole round and smooth, then try seating again.

I have tried the 'hit the ball' method but find it to be iffy sometimes. Someone made the suggestion to lap the seat and I have found that to yield a good seat most every time, as long as the hole and the flat have good finish. A ball epoxied on the end of a stick works well, and I've used soft metal or plastic balls for the lap with good success. Need fine lapping compound also.

Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline john mills

  • Full Member
  • ****
  • Posts: 125
Re: Steam Tractor 3/4" (Rudy K)
« Reply #1028 on: May 10, 2018, 11:30:54 PM »
I have always reamed the hole ,the d bit should cut with out chatter run slow and make sure it cuts out at the full depth  complete turns at the depth .ream again to make sure a sharp edge.then only a light tap with a flat ended
punch,,not a great bash with a big hammer.

Offline Tennessee Whiskey

  • Full Member
  • *****
  • Posts: 3776
  • Springfield, Tennessee. USA
Re: Steam Tractor 3/4" (Rudy K)
« Reply #1029 on: May 11, 2018, 12:15:38 AM »
Thanks for the reference Kim  8). If you decide to have another go with the “D - bit”, try turning it by hand with just a fanny hair of pressure on the quill. Bronze could be a bit harder and require a bigger hammer: but, here in Tennessee we rank every job on the size hammer it took to get the job done :lolb:. I’ll be following along for updates.

Cletus

Offline steamboatmodel

  • Full Member
  • ****
  • Posts: 150
Re: Steam Tractor 3/4" (Rudy K)
« Reply #1030 on: May 11, 2018, 12:53:37 AM »
It does not work as well as proper lapping compound, but tooth paste or polish will work.
Gerald.
Be wary of strong drink. It can make you shoot at tax collectors--and miss. Lazarus Long

Offline Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3723
  • Portland, Oregon, USA
Re: Steam Tractor 3/4" (Rudy K)
« Reply #1031 on: May 11, 2018, 03:26:19 AM »
Thanks Pete, John, Cletus and Gerald,
I really appreciate the comments.  And, after a day of reflection, I'm going to give it another go.  I was a tad frustrated with it this morning.  But hey, if I get this working, all I'm going to do is work on the next problem.  So, why not work on this one a little longer and see if I can figure it out!  (He says, with his more optimistic side shining through :))

John, you gave a good step by step. I may try that before I move to lapping.  I've been giving it a pretty good wallop, so maybe I'm being too aggressive.  I'll try a much gentler rap after I get the surfaces cleaned up again.

And if that doesn't cut it, I will give lapping a go.  I've got some pumice stone that I've used for wood working finishes.  Wonder if that would work here?  It's at least something I have on hand!

I will put your ideas into action next time I'm out in the shop.

Thanks again for your words of encouragement and advice!
Kim

Offline Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3723
  • Portland, Oregon, USA
Re: Steam Tractor 3/4" (Rudy K)
« Reply #1032 on: May 12, 2018, 12:21:46 AM »
OK, here’s the results of my next series of tests.

1)   First I did John’s process: used the D-bit again to re-surface the seat, then used the 1/8” reamer to clean up the hole.  Then I gave a light bearing whack, reassembled, and no luck.  Still the same leaking.
2)   Second, I tried the lapping thing. I used red Loctite to fix a bearing to the end of a 1/8” steel rod.  Then, using that I made a little paste with oil and the pumice stone that I had.  This is 4F powder, so its very fine. I twisted about with that for a while on the bearing seat, then tried it again.  Still the same.  Leaked like a sieve.
3)   Third, I made a check valve.  The rest of this post relates to that.

I drew up a quick plan for a little check valve.  I based it on materials I had – a 5/32” bearing, and 3/8” Hex brass.

Here’s the main body.  First I drilled & reamed a 1/8” hole about 1 1/8” deep:


Next, I drilled and tapped some 5/16”-24 threads.  This will be the input end of the check valve (hook directly to the pump).


Drilling a 1/8” side hole for the output.


And widening to 1/4" for the place to solder on the output port.


I made the output port and the plug to hold the spring and bearing.  No pics of these since they were nearly identical to parts made a few days back.


Well, I got a little excited with my silver soldering. Can’t blame this on the humming bird :(.  Actually, now that I think about it, I’m going to blame it on all the welding I recently did.  There’s a BIG difference in soldering vs welding.  I’m going to have to get my ‘soldering legs’ back.  I really fried this puppy.  But I think I can clean it up and still use it.


Back to the hex collet – faced off the other end.


Drilled it #3:


Then used the D-bit to ream it out a tad and make the valve seat.


Thread 1/4"-28 for the plug.


Did a very gentle bearing whack, then assembled it, and here we are on the pump:




Interestingly, this didn’t seem to work much better.  So, I tried a harder whack, and it seemed to actually hold up to about 20 lbs.  That was twice as good at before.

But I kept trying it – pumping it some more and it went up to 35, then 40, then 50, and then 60!  What’s interesting, is that it seemed to get a little better with use.  Maybe the ball bearing/seat combo has to break in together or something?  I don’t know, but it really started to work!



So now I’ve left it sitting there for a while watching the pressure go down.  Here’s a table of my readings:

T (min) P (lbs)
0 63
14 58.5
23 55
30 52
45 49
55 46.5
87 42.5
110 38.5
129 36

And you can’t have a table like this without a graph:


It looks like my valve is leaking about 1/3 lb per minute for the first 30 min, and about .2 lb/min for the next hour and flattening out.  Probably a reasonable curve as the loss will slow as the pressure decreases.

Now my question (for any of you who have made it this far):  Is this good enough to do a boiler test with?  Or will I be fighting the system more than the boiler?

Kim

Offline 10KPete

  • Full Member
  • ****
  • Posts: 1565
  • Nordland, WA, USA
Re: Steam Tractor 3/4" (Rudy K)
« Reply #1033 on: May 12, 2018, 12:30:22 AM »
You need not rely on the pump check. For testing you can put a shut-off valve in the line...

Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline crueby

  • Full Member
  • *****
  • Posts: 9179
  • Rochester NY
Re: Steam Tractor 3/4" (Rudy K)
« Reply #1034 on: May 12, 2018, 12:31:58 AM »
Just a thought - have you checked to make sure there is no leak at the gauge end of the tubing, or in the union from the pump to the tubing?