Water pump piping on Emma Voctoria

Hi all, I am making the water pump on Emma at the moment and have a query.

The connections are shown as 3/8" x 32 tpi which I have done.

However the water pipe sizes are stated as 3/16".

A 3/16" pipe union falls through a 3/8" union nut.. Is this an error or am I misunderstanding something somewhere.

Bill D.

Bill. Hobbynut has got past that stage so if you can get hold of him,or look in his album it will help.

bill,

dont forget the diameter of the nipple around the pipe to be silver soldered on.

in the unlikely event of your unions not being standard they arent difficult to make.

3/8" x 32 tpi seems big to me. 5/16" x 32 tpi is standard for 3/16" dia pipe with standard nipples.

cheers,

julian

The pump connections are definitely shown as 3/8 x 32. I am not yet familiar enough with these pipe sizes to immediately realise 3/16 pipe and 3/8 nut were not a match. I am surprised no one else has queried this but maybe the more experienced of you guys would have just sorted it in your own way.

I assume that using 1/4 pipe rather than 3/16 would not be a problem, otherwise I will make non standard cones.

The water passages in the pump are 3/16" by the way.

Bill D

3/16" dia passageways on a pump for a small 5"g loco seems excessive! the RAILMOTOR passages are 1/8" dia seats for the balls of 5/32" dia. Unions connections are 1/4 x 40 tpi, hence my surprise at the 3/8" x 32 tpi connections.

i never fitted the handpump made in 1983 same time as the axlepump, and the handpump is still in regular use on my boiler test rig. the loco i sold many years ago but the guy i sold it to wont sell it back to me as he regularly runs it and wont part with it!

cheers,

julian

Henry has responded before to queries on his design, it would be good if he sees this and gives his thoughts on my question and Julian's comments on here and post in beginners section.

Bill D.

Hello Bill

There is no reason why you cannot make the pump inlet and outlet fittings with 5/16" x 32 threads and reduce the bore of the fittings to 5/32" dia. if you prefer and use commercially available nipples. I make all my own fittings including nipples ( you will see these covered later in the series ) so I do not have a problem using 3/8" x 32 threads. I would not consider going to 1/4"dia. pipe, 3/16" being adequate for this size of loco.

Regards

Henry

Henry,

no one suggested 1/4" dia pipe.

5/32 dia pipe with 1/8" seats and 5/32" dia balls is more than adequate for this size pump for a small 5"g loco.

cheers,

julian

Julian, Henry mentioned 1/4" pipe because I did in my thread of the 10th.

Thank you for reply Henry, I think I will stick with the 3/8 connections I have already made and make some cones to suit 3/16 pipe.

Bill D

I had no problem with the 3/8 size threads. I used 3/8-32, but that was just because I misplaced the -40.

I have been searching for dimensions of standard nipples, most are obvious but need the angle of the taper seat.

Can anyone help please?

Bill D.

hi bill,

angle is same as a centre/slocombe drill ie 60 degrees. slow speed to avoid chatter.

cheers,

julian

Thanks Julian

Bill

Bill, how did you get on with the pump ?. Have you an update?

I made a right mess of my first one so shelved it. (now scrapped) Gone back to it and decided to make another. learned that these things can't be rushed. This one I hope is ok. Just got the 3 nuts (inlet,outlet and blanking plug to make,seat the balls and see what happens... John .

Hi John, I got on ok, pump finished and installed, whether it works or not is another thing though.

I still find it is a case of two steps forward one back sometimes though (and sometimes vice versa)

Most times I know what I have done wrong, it is usually a case of just not taking enough care in setting up.

Getting there though bit by bit. My first engine, in fact only my third model (GLR vertical boiler & Jan Ridders simple two stroke engine) so I suppose I need to be a bit more patient in my skills development. Still struggle with silver soldering, very hit & miss and frustratingly never sure what I have done wrong as I seemed to have followed all the usual rules, again just practice I hope as the boiler build is looming.

Bill D.