Author Topic: Stuart Boiler Feed Pump  (Read 62236 times)

Offline Florian Eberhard

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Re: Stuart Boiler Feed Pump
« Reply #75 on: November 25, 2013, 09:07:59 PM »
that is after I had to fill in the oversize hole that I made before reading your post.

Hey George

That sounds like you are working on a stuart pump just right now..?
If so, would you maybe put some pitures up here aswell? I would be interested for shure!

Florian

Offline Florian Eberhard

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Re: Stuart Boiler Feed Pump
« Reply #76 on: November 25, 2013, 10:19:24 PM »
After finishing the valve chest (almost...), I machined the shuttle valve piston from a 5mm dia stainless steel rod.
As you can see, I had to start three times.  :insane:
The first one got one mm to short, I still have no idea why.
The second one had the correct length but I have cut the groove for the o-ring a little too deep so the o-ring was not pre-loaded a little (as it should to get it steam tight).
And finally the third one came out right. (though i had to replace it aswell - but more about this when I get there) One of the pictures shows the steam chest with the shuttle piston and valve installed.
I already machined the first piston shaft / pump ram some time ago. I decided to use a lapping ring to finish the surface.
But I had to find out that i had used the wrong grade of stainless because this one tends to bite (its 1.4301 if you are familiar with that notation).
This also happened during the lapping process and so I got a quite deep helix formed groove in my almost finished shaft. That really pissed me of because the pump ram was already finished. You will notice that the pump ram is bigger in diameter. It has 8mm, thats 2mm more than the piston rod which has 6mm.

I have by the way also increased the cylinder diameter from 12mm to 14mm so the cylinder should be able to deal with the greater amount of force required for that pump ram. Well - now I made another attempt using another grade of stainless now (1.4021) You can see the cylinder shaft side being machined. The stub at the live center side is where the cone and the thread will be machined and I have already turned them to in about 5.98mm so that is slightly smaller than the 6.02mm I am heading for to enable 0.02mm being lapped away for a perfect finish and cylindricity. 
Lapping took quite long, in about 1 hour for the cylinder shaft and 30 minutes for the ram. I was rotating the shaft with an cordless screwdriver. ( I used some brass sheet metal stripes bent around the shaft to protect it from the hard drill chuck jaws)

Mission accomplished! The shaft came out quite nice. For comparison, the last picture shows it right next to the one that went bad during the lapping process.




« Last Edit: August 12, 2017, 09:24:17 PM by Florian Eberhard »

Offline Don1966

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Re: Stuart Boiler Feed Pump
« Reply #77 on: November 26, 2013, 12:50:09 AM »
Looking good Florian and I love your Techniques.


Don

Offline smfr

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Re: Stuart Boiler Feed Pump
« Reply #78 on: November 26, 2013, 03:36:05 AM »
Very nice, Florian, and I like the lapping ring. :ThumbsUp: :ThumbsUp:

Simon

Offline derekwarner

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Re: Stuart Boiler Feed Pump
« Reply #79 on: November 26, 2013, 04:23:09 AM »
Florian.......

The original shaft [1.4301] being a 300 series grade is austenitic & shall we say non rusting...however with poorer machining qualities
The second shaft [1.4021] being a 400 series grade is martensitic & although it has slightly superior machinability qualities is technically not capable of being rust resistant

1.4571 material is readily commercially available & has marginally superior machining qualities over 1.4301......
1.4571 also has the advantage of being from the 300 series family with totally rust free substrate

A consideration could be to use 1.4571, then followed by grind, chrome & regrind which would provide a totally rust free substrate & surface hardness to 65Rc and to say 0.3 umRa surface roughness

The 65Rc & the 0.3 umRa being the optimum considerations for superior design.......Derek

« Last Edit: November 26, 2013, 08:23:41 AM by derekwarner_decoy »
Derek L Warner - Honorary Secretary [Retired]
Illawarra Live Steamers Co-op - Australia
www.ils.org.au

Offline Florian Eberhard

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Re: Stuart Boiler Feed Pump
« Reply #80 on: November 26, 2013, 10:47:30 AM »
Hi Derek

Thanks for bringing that fact to my attention.

Chrome plating, grinding and more would be a little over engineerd though I am shure it would result in a perfectly running pump. However - I don't have the possibility to do it by myself and therefore It would also cost some money. (I guess more than I want to spend for it)
I will see what happens with 1.4021 in that little pump. Polished surfaces are as far as i know  good if its about preventing corrosion.
The reason for using 1.4021 is not the machinability but the fact that it seems to wear with a better surface than 1.4301 (I don't know it yet but I have been told it would be that way. So I will see how it turns out) and of course that i had it around (Ordered it for some parts that I wanted to harden and that should not corrode fast)

Florian

Offline K.B.C

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Re: Stuart Boiler Feed Pump
« Reply #81 on: November 26, 2013, 12:48:25 PM »
that is after I had to fill in the oversize hole that I made before reading your post.

Hey George

That sounds like you are working on a stuart pump just right now..?
If so, would you maybe put some pitures up here aswell? I would be interested for shure!

Florian

Florian,
Yes I am making a boiler feed pump at present and although I have made a few I have tried some of the methods that you have posted.
Unfortunately this set of castings are the poorest that I have ever tackled. the casting at the water pump end is very out of line and difficult to grip in the 4- jaw to enable me to machine the steam engine end which is the method that I have always employed and then bore straight thro' after drilling out with a 29/64" drill.
I tried your method of clamping on the face plate but even though it was clamped up tight the casting moved when I started machining the end for the engine. so it was back to my old method but you can see in the pic that when I bored thro' it was off center, not much that I could do even though I had tried to square up the water pump end of the casting before boring.
I have also found out the the holding down bolt feet on the casting  is out of line so the bolt pitches will be different to each other.

Apart from these miss aligned parts I am please that on following your post on drilling for the Auxiliary valve has worked out perfect.
Thanks again.

George.
Your never too old to learn.

Offline K.B.C

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Re: Stuart Boiler Feed Pump
« Reply #82 on: November 27, 2013, 12:11:31 AM »
Florian,
Having just completed the piston and shaft on my pump it has raised a question on your post No 76 where you have the piston rod shaft at 6 mm ( 1/4" ) and the water pump at 8mm ( 5/16" ).

Why have you done this as the designed dia of the water pump is 6 mm ( 1/4" ) and it pumps copious amounts of water at that dia ?

It also means that you will have to feed the shaft in from the water pump end and thread thro' the seal and the gland nut, slide the auxiliary valve rod actuating arm on and then slide it thro' the next gland nut and then thro' the seal on the engine with the steam cylinder bolted on and finally screw on the piston.

This is going to take up quite a bit of time if you have to take the shaft back out, whereas if you stick to the design size of 6 mm ( 1/4" ) with the piston fixed on you can feed in from the opposite end of the steam cylinder, which is much easier.

It's just a thought but maybe you could let me know how you are going to do it as I can't see any advantage in your design change..

George.
« Last Edit: November 27, 2013, 12:16:27 AM by K.B.C »
Your never too old to learn.

Offline Florian Eberhard

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Re: Stuart Boiler Feed Pump
« Reply #83 on: November 27, 2013, 08:16:18 AM »
Hi George

I wanted to increase the bore of the steam cylinder and of the water pump aswell (to prevent the pump from going "too easy")
But I simply didn't want to have a 8mm cylinder shaft as it seemed a little too big for me (and wouldn't have worked with the tappet because that would have not enought diameter/width on the lower end)

I will assemble the pump likewise:
1. fix the pump body to the cast iron base
2. add the cylinder cover on the ohter end
3. insert the pump/cylinder shaft from the pump side, add the tappet in the middle
4. fix the piston to the shaft
5. add the rest of the cylinder.

Offline K.B.C

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Re: Stuart Boiler Feed Pump
« Reply #84 on: November 27, 2013, 10:30:18 AM »
Hi Florian,
It really is the only way to assemble the pump, but how are you going to fix the 2- C/Sk screws that hold the bottom cover to the cylinder.
This means that you will have to fix them and then offer the piston to the rod from the top of the cylinder while the cylinder is affixed to the bottom cover.

It would have been so much easier for assembly and maintenance if you had left the pump ram at 6 mm ( 1/4" )  which means that you could assemble everything and then offer the piston fitted to the 6 mm rod from the back end of the cylinder.

Must compliment you on your machining, first class.

George.
Your never too old to learn.

Offline steamer

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Re: Stuart Boiler Feed Pump
« Reply #85 on: November 27, 2013, 10:54:20 AM »
This will be one of those.....Let's give it try projects.....though knowing Florian as I do, I am sure he can give it the "business" necessary to make it work the way he wants.

Love the build Florian!....please continue!

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Florian Eberhard

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Re: Stuart Boiler Feed Pump
« Reply #86 on: November 27, 2013, 11:06:43 AM »
Hey George

Instead of using 2 screws to fix the cylinder unit to the cast iron base and 2 screws to connect the cylinder with the cylinder cover, I will not have any screws which connect cover and Cylinder before mounting it.
I will have 4 Screws connecting the cylinder with the cast iron base though the lowest screw - actually I have to talk about stays - the lowest stay will go all through the cylinder and will have a threaded end in the cast iron base and the other end at the cylinder cover at the end of the pump.

But you will see that when I am going to make the studs.

Florian

Offline K.B.C

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Re: Stuart Boiler Feed Pump
« Reply #87 on: November 27, 2013, 11:35:29 AM »
Hi Florian,

I am a bit like a skier going off piste and not knowing what to expect, I am used to working with the Stuart drawing so it's good to hear that you have designed a way around the original design and I look forward to seeing how.

I keep saying  " you are never too old to learn " and you have certainly got the old gray matter working.

Do you intend to feed a steam boiler with the pump or just to run it on air ?

George.
Your never too old to learn.

Offline Florian Eberhard

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Re: Stuart Boiler Feed Pump
« Reply #88 on: November 27, 2013, 11:51:55 AM »
I will use it as a pump in combination with my scotch boiler I guess. (Or probably with a vertical one I got recently)
But definitely under steam!!!  ^-^
« Last Edit: November 27, 2013, 09:19:44 PM by Florian Eberhard »

Offline Florian Eberhard

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Re: Stuart Boiler Feed Pump
« Reply #89 on: November 27, 2013, 09:41:52 PM »
I think its time, istn't it  :Lol:

Well, here I go:


Next was the piston. I first parted off a piece of the chunck of material that was delievered. This piece was then held in collets and the inner contours were machined. First the conic bore and then the other side where I had to make room for the nut. The outer diameter was finished by holding the piston with its shaft and taking the shaft in collets. I usually do this to get minimal runout. (And I am shure many of you also do it that way). After finishing it, I have put it into the cylinder (still using the machining nut) Then I also made the final nut and assembled everything.

Next were three gland nuts. They were all made the same way (more or less)
You may remember my thread about thread milling. This is what I used it for. I first machined the thread and the whole inner side of the gland nuts. Then switched over to the milling machine to mill the slots.
That was followed by parting off and finally finishing the ohter end. The Radius has been hand made with a little file (and thats why there are no pictures of this - I only have two hands and needed them both...  ::)
However, the last picture shows what they look like:

Thats it for now - Ill continue soon (tomorrow maybe..?)
« Last Edit: August 12, 2017, 09:28:07 PM by Florian Eberhard »

 

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