A surface relative to a cylinder??

[Rod999]

In machining the Breisch duplex steam pump I've run into a bit of a quandary. It seems basic and I have no issues scribing on the surface plate, however I wanted to be more accurate than "milling to a scribed line". So, I have bored the cylinders for the pump end and now need to mill the bottom two projections that bolt to the base-plate. When bolted down the pump cylinders need perfect alignment to the cylinders of the steam end. All I can think of is to make up a tight fitting plug that will stick out of the cylinder enough to zero out the quill of the mill and then back up the distance quoted in the prints to miil these two nubs.
         The same issue comes up on the steam end, and there it's both the top and bottom. The bottom will align the cylinders, and then the steam chest needs to align with the linkage, so here we have to be even more accurate~
        In doing the pump end I started by boring the cylinders on the center line of the casting. Maybe that was not the best starting point. Sometimes working castings hurts my head~

[crueby]

Without a picture not sure I know exactly what these parts look like, but in general the best way to get the end face perpendicular to the bore is to face the end and bore the hole in the same chucking. If you need the opposite end accurate as well, turning a close fitting expanding arbor and using that to hold the bore while turning the other end will work well, just dont un-chuck the arbor after turning it and before using it.


Sorry if that is not the operation you are talking about!

[Jo]

Lets starts with a warning: Duplex steam pumps i.e. the sort where the pumps and the cylinders share a pump/piston rod between the two and are spaced with some sort of bars, are not a beginners engine build.

As Chris said you need to bore/face the cylinders of both the pump and the cylinders from the end that needs to point at each other. Then a tight fitting bar through the bores would give you alignment necessary to mill the bottom of the cylinder/pump pair at the same time. In this manner they both have the same distance to the base.

Is this a two cylinder pump? If so that makes things more interesting.

Jo

[Rod999]

           I've already replied twice, but I guess my computer is too slow to get the photo in. However, Jo your idea of the test-bar to fit both the pump & steam end is what I needed. I have already bored and faced the pump end on a K&T #2HL (small horizontal mill). Like I mentioned I could find the hight with a test bar and digital quil, but never would have thought to make the bar fit both the pump & steam cylinder at the same time. This unit has a casting between steam end and pump which bolts up much like the end caps, so we have plenty of places to screw up the fit. I also see that some of the castings didn't get cast square in that the top mold half wasn't square to the bottom, but like I said I can't get photos in, so it's hard to show~

[Jo]

Rod how big are the photos? If they are over 1MB then the software will not let you load them. Reduce their size. I find pictures of about 800 by 600 pixels is good enough unless there is a need for the extra detail.

Jo

[Rod999]

        Jo, I don't have a clue as to photo size, but follow directions well when needed. I'm 70 now and find computers very handy, and equally annoying~

[Rod999]

       Would 3.7mb be what you're looking for

[Jo]

That is huge... the forum software will not let you load it  You would need a 55+" tv to view it at its full resolution

If you are using Windows as an operating system select the file then choose edit and it should let you reduce the size.

Jo

[Rod999]

I resized & de colored it to 68KB & that failed too, however at least you saved me making a mess of this via the test bar. I'm on a macbook pro that's old and tired

[Rod999]

I got in the camera and resized some more~

[Rod999]

This shows the misalignment, this is the intake port of the pump, there is really no extra bronze here to make the hole (outer dimension) round, in making it round what should measure 1&5/8" comes out 1.518 not a big deal, but - - -

[Rod999]

        Here is what started all this~

[crueby]

Pictures came through fine that time - thats a lot more complex shape than I was thinking.

[Jo]

Ok so you have two bores on two castings that must be parallel to each other, square to the centre end of the castings and spaced at the same distance. The centre section seems to act as piston rod guides so will need exactly the same spacing so there are lots of opportunities to add unintended features here  so the only answer would be to use a jig to assure alignment between the bores of everything 

You do not have to match the measurements on the drawings, all you need to achieve is parallelism, equal spacing and that the central faces are all square - the jig will provide that. Once you have that difficult bit done you can secure the three parts together and get the pistons running freely between them and afterwards face them while together so they mount on the plate 


I rather like the look of that model I will have to keep my eyes out for a set of castings   

Jo

[Rod999]

This is the connector between the steam and water end, a jig plate will be easy enough for the bolt holes, I have some ideas for the projections, but need to think on that for a while~

[tghs]

wondering on how the gland recesses inside the frame will get machined,,central cutter on a 1/4" rod?

[Jo]

The Jig plate needs to use the 1 1/4" and the 1" diameters on all parts as locators = one jig for the cylinder, pumps and that spacer, something like attached. Think a 1 1/4" counter bore with a suitable 1 1/4" to 1" reduction bush, then a pair to take the 1 1/4" counterbore to a 1/4" boss and 1 1/4" to 1" boss to register in the bores of the cylinder and pump.

Once you have started you need to leave the jig where it is for the second set of bores and do all three parts without moving the jig - I'd clamp some how not bolt it in place. If you look at my sketch you can see holes to hold the bushes in place and another set of holes round the outside which I would used for the clamp bolts.   

Jo

[Rod999]

             That plate looks like it would work just fine~ I see a very similar machine on youtube listed as a large duplex boiler feed pump - similar but not exact~

[Jo]

We seem to have gained a set of castings for a different Duplex Steam Pump, this one is the Southworth small Duplex pump 

I hope to learn more about them tomorrow (assuming they are offered up as the set of castings for our Thursday night Casting fondle  ) It will have similar problems for machining as your one 

Jo

[Rod999]

       I dug the steam cyl. out of the box  being it's next to be made ready, Here I'm just going to clean up the exhaust port, so as to scribe the center line & help find some squareness~