Author Topic: PMR Feed Pump build  (Read 10620 times)

Offline sshire

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PMR Feed Pump build
« on: August 29, 2013, 06:47:11 PM »
While I'm waiting for the new boiler tube and end plates, I started on the feed pump. If you've missed the saga of "The Bass Ackwards Boiler Build", search for PMR Horizontal Boiler. 

The feed pump is also a PM Research kit and is up to their usual quality level and completeness of parts. The only change I'm going to make is to the pump handle's clevis pins. The plans show them retained with cotter pins. I'm not wild about the look of those, so they will be replaced with .125 E-clips. Wait. There is one more change. Im going to try Viton balls instead of the stainless ones in the kit. Thanks for that suggestion goes to fcheslop on the MEM Forum.

As with every build I've done, I try to start with a trammed mill whether it needs it or not.



And that's close enough. The BP has to be the easiest mill to tram.



First step; flatten the bottom so I have some sort of reference surface. I'm using a Glacern 2" 45 degree face mill.





With the bottom flat, I mounted the casting on an angle plate and used a square to get it straight. I did try to indicate it with a DTI but the rough surface of the casting had the Interapid doing some sort of Swiss fertility dance. I'm calling this close enough.



After milling the piston housing flat, I flipped the casting over, straightened it again and milled the inlet and outlet port housings.



The Foredom flex shaft tool with sanding drums and various brass brush wheels, files and sandpaper got me to this point. I'll do the final cleanup when it's all done and ready for primer and paint.



There are very few parts to make for the feed pump; drilling and tapping of the main casting, handle, piston, ball valves, and gland nuts. Should be a fairly quick build and then back to the boiler.

More pump parts tomorrow. Stay tuned.

Best
Stan




Best,
Stan

Offline NickG

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Re: PMR Feed Pump build
« Reply #1 on: August 29, 2013, 08:02:09 PM »
Nice start Stan. Does the BP pivot front to
Back too? Or is it necessary in that plane because you can swing the whole turett?

Offline sshire

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Re: PMR Feed Pump build
« Reply #2 on: August 29, 2013, 08:29:07 PM »
Nick
The tramming (or tilting if you need to angle mill or drill) is done with worm gears. A 3/4" hex protrudes from the top of the ram for front to back tilt and  one on the side for left-right tilt. Just loosening the locking bolts for a particular axis, gives a bit  of drag to the wrench. I can easily move less than a thou.
Damn brilliant.
Best,
Stan

Online b.lindsey

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Re: PMR Feed Pump build
« Reply #3 on: August 29, 2013, 09:32:48 PM »
Yipee!!!  Looking forward to this one too Stan!!

Bill

Offline NickG

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Re: PMR Feed Pump build
« Reply #4 on: August 29, 2013, 10:01:57 PM »
That is great, on mine i would need to shim the whole column for front to back. Think i checked that when bought it and it was ok. Not checked the side to side fir a while though!

Offline Don1966

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Re: PMR Feed Pump build
« Reply #5 on: August 29, 2013, 11:52:05 PM »
Stan I am also glad your doing the feed pump. Mind is waiting under the bench to be done also. Nice start on it thought. By the way do you have the angle grinder attachment for your Foredom, I love mine?

Don
« Last Edit: August 29, 2013, 11:55:52 PM by Don1966 »

Online b.lindsey

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Re: PMR Feed Pump build
« Reply #6 on: August 30, 2013, 12:48:51 AM »
Don, do you mean the head that looks more like a dental tool oor something else?

Bill

Offline Don1966

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Re: PMR Feed Pump build
« Reply #7 on: August 30, 2013, 02:14:56 AM »
Don, do you mean the head that looks more like a dental tool oor something else?

Bill
No Bill that is a collet holder this is the angle grinder great for cleaning casting up with.
http://www.foredom.net/ak69109.aspx
This is the one that looks like a dental tool http://www.foredom.net/a69224.aspx

Don

Offline Steamer5

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Re: PMR Feed Pump build
« Reply #8 on: August 30, 2013, 10:45:50 AM »
Hi Stan,
 Nice start, following your boiler build too......you are doing a great job on that as well. Only comment would be that watch ya balls.....sorry Jo. I used nitrile ones for the non returns on my loco, they work great.......for quite awhile. I started having some not non return issues, so new seats were made & fitted, ok for a bit then trouble again. By a bit of a chance I found that they had changed shape! So depending on how the dropped depended on how they sealed! Easy fixed give them to the workshop elf........he loves them, haven't see them since I put them othe floor, put in new ones. So now I change them as required!

Cheers Kerrin
Get excited and make something!

Offline Jo

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Re: PMR Feed Pump build
« Reply #9 on: August 30, 2013, 11:04:36 AM »
Yes nitrile balls have their little challenges. If you can fit bobbins:



In my experience the bobbin (a sort of T valve) is best made from stainless steel, with the three flutes cut at 120 degrees into the stem of the "T", which goes into the feed pipe. You also need to cut a seat in the underside of the head of the T for the "o" ring.

The bobbin should be a loose fit in both the valve body and the feed pipe diameters. The stem length should be the bore of the valve plus the "o" ring. The head length, including the "o" ring, should be the distance above the seat minus the original ball clearance. (I must draw this out  :hammerbash:)

They also have the advantage that if you drop them they, normally, do not roll so far.

An alternative design which uses the nut above as the guide is this commercial one:





Jo
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Offline sshire

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Re: PMR Feed Pump build
« Reply #10 on: August 30, 2013, 01:20:52 PM »
I'm confused. Are the bobbins fitted inside the feed pump? I can't picture how this would work.

Also, what is a non-return? So much to learn.
Best,
Stan

Offline sshire

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Re: PMR Feed Pump build
« Reply #11 on: August 30, 2013, 01:27:59 PM »
Just looked it up. The non-return prevents boiler water from returning to the feed pump.
Is there a separate "non- return" valve or some such?
Why is this the first time I'm hearing this? Is this a steam conspiracy where only partial information is given to non-initiates?
Best,
Stan

Offline Jo

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Re: PMR Feed Pump build
« Reply #12 on: August 30, 2013, 02:53:30 PM »
Your balls (in the pump) are operating as the non return valve so that when you move the handle the water is sucked into the pump and then on the next movement of the handle it continues out in the right direction. Think of a pipe with water in it and in the middle is a ball against a shoulder, if it is sucked away from the shoulder then water can flow around it but if you try to push the other way the ball will seal the hole and the water will have to find another way out, which should be past another valve and into your boiler.

Instead of using a ball you can use a bobbin. Bobbins have a larger sealing area  ;) But balls have worked very nicely for years and years...

Jo
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Offline sshire

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Re: PMR Feed Pump build
« Reply #13 on: August 30, 2013, 03:47:55 PM »
Thanks, Jo.
I'll try the Viton balls and, if I'm not happy with them, I've got the stainless steel ones that came with the kit.

Much less confused
Stan
Best,
Stan

Offline Steamer5

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Re: PMR Feed Pump build
« Reply #14 on: August 30, 2013, 07:30:08 PM »
Hi Stan,
 Sorry to cause you some confusion, that wasn't my intention. Just forgot that we all use terms that others may not of heard off. Just wanted to pass on my experience with soft instead of stainless balls. Thanks Jo for a great explanation, & the photos of your bobbins, I'll look into seeing if I can get them to fit.

Cheers Kerrin
Get excited and make something!