Chris's Holly Pumping Engine Build

[crueby]

Chris:

You've probably already said, but what slicer do you use?

A couple of questions about the pumping section:

You say the pump core section will be working.  Do you mean the pump parts will be in the correct location and connected to the engine, but not truely functional - or do you intend to be able to pump something with it?

If you're going to pump something with it, do you intend to hide the inlet and discharge piping inside the printed piping, or actually use the printed piping as inlet and discharge?

Don

The pumps will be (hopefully) fully functional. What I'm planning on doing is have the central pump chamber match the original, but the check valves in the scaled-down version would be teensy. And there are thousands of them. So, I am printing the valve housings, hollow, and will put tubing/tees/elbows inside to direct the water, and put check valves on the inlet/outlet of the pump chamber, inside the printed housings. I'd like to be able to run the tubing from the inlet/outlet to a water tank to show the pumping action while running the engine. It wont be pushing against pressure like the real one did, so plastic tubing should work. Going to mock it up outside the model to test, once its sealed up/bolted in, it would be a real chore to take it apart again!  I've got some stainless ball assorted-sizes coming, and I have the tubing/connectors on the shelf. I'm going to turn up the first pump chamber, and do some tests. The plunger is about 1" diameter, so it will want to move a lot of water (the real engine pumped almost 1000 gallons per revolution of the engine).

[crueby]

I get asked a lot about using large size brass in my models, which when buying small lengths is REALLY expensive. I needed some more 2-1/4" diameter stock for the pump chambers, each is nearly 4" long. I need 3 of them. Plus will use more on other parts later on this model, and on future models.

For comparison, I went to Online Metals (middle of the range on pricing, prices do vary by source/size/date, this is just an example). To get 4" long pieces, they are currently $68 apiece, or a 12" length is $168. Plus shipping, probably at least $20.

 Then I went over to Yarde Metals, where I buy a lot of larger stock - they sell offcuts, 'drops', in their Drop Zone section.  They had a 36" length of 2-1/4" 360 brass roundbar, thats triple the length, for $217. And the shipping on 42 pounds of bar was only $13. Hmmm, which will I go for....  Very little price difference, enough bar to last the next few projects instead of part of this one.

This is how I usually buy, when I can find the offcuts or bar on sale - buying in longer lengths and stock up, rather than buying just enough for what I need this week, paying higher per-foot prices and lots for shipping costs. Yes, I am laying out a little more right now, but in the long run its hugely cheaper. Buying offcuts requires checking back with suppliers more often since their stock changes daily/weekly, but for a 60% savings? Easy to justify.

Okay, off soapbox, for now! I get questions on this a lot, thought I'd throw this out there. If you have machine shops or metal dealers near you, its worth stopping in for a chat, many will sell leftovers cheap.

[cnr6400]

I just wish I had Ye Olde Scrappe Yarde       in my town.........the metal suppliers local to me are not good.

Great progress on the Holly engine. 3D prints look fabulous! 

[propforward]

Excellent approach to material buying. Going to look for a local material supplier!

[crueby]

Excellent approach to material buying. Going to look for a local material supplier!

For those in the US, the Yarde Metals I mentioned is a large commercial supplier in the northeast. Go to thier website, and look for thier Drop Zone, its where they list thier offcuts, for buying online. Selection varies weekly, most pieces are two to three foot long. Good if you don't have a local place.

[propforward]

Brilliant! Good to know - thanks!

[Kim]

Good input, Chris!

Unfortunately, I've found that Yarde Metal's shipping is not so favorable to me, since I'm in the NW.  But Online Metals shipping is MUCH better for me than for you.  The metal isn't any cheaper for me though

I've also found that you have to check around.  Sometimes SpeedyMetals is cheaper and sometimes Online Metals is.  I order from both.

And I've listened to your recommendation and do check for cutoff's and order them when I can (when shipping doesn't chew up all the potential savings at least!)

Kim

[crueby]

Good input, Chris!

Unfortunately, I've found that Yarde Metal's shipping is not so favorable to me, since I'm in the NW.  But Online Metals shipping is MUCH better for me than for you.  The metal isn't any cheaper for me though

I've also found that you have to check around.  Sometimes SpeedyMetals is cheaper and sometimes Online Metals is.  I order from both.

And I've listened to your recommendation and do check for cutoff's and order them when I can (when shipping doesn't chew up all the potential savings at least!)

Kim

Agreed on all points. The prices and shipping vary a lot, hard to predict!

[steamboatmodel]

North of the Border it is usually Metals Supermarket or some of the recycling places. With the recycling spots you usually end up with mystery metals, usually good on copper pipe though.
Gerald.
 

[crueby]

Today was a boring turning day.  Well, technically,. turning then boring!   

Started in on the first of the pump cylinders. There are three of them, one per engine cylinder, the plunger driven by rods coming down from the crosshead above.  I started with a length of 2-1/4" diameter brass roundbar, and turned the outside to shape.


The chamber flares out in the center to give the water space around the plunger. The plunger is about 1" diameter, with a 2" stroke, and the chamber is a little over 3" long overall. To give swinging room and room for the chuck jaws on the lathe I put the riser blocks in on the lathe. After shaping the outside, the part was swapped end for end and moved to the mill to drill the pattern of 16 2-56 clear mounting holes in the base. Back on the lathe, the bottom was trimmed to final length (it was left a little long to get the part past the chuck jaws). Then it was bolted to a steel faceplate that had a matching pattern of tapped holes, to start boring it out. I initially tried holding the part in the chuck for boring, but with that much weight and overhang the brass kept wiggling a little loose in the jaws, so I went for the faceplate - much more secure.

I drilled/bored out the inside to the 1" size of the plunger, then enlarged the inside more, and turned in the seat for an o-ring for a seal. There will be a cap that sits above the o-ring to hold it in place. On the original engine they used a large flat ring seal, not sure what material, but basically the same idea. The plunger does not have to seal down its length like a engine piston would, just needs the seal at the opening - the plunger displaces the water inside the chamber to force it out, and on the upstroke the volume un-displaced draws in the next 'chunk' of water. The chamber looks a lot like an old style milk can. Once all the boring is complete on the chambers, I'll make and add the pipe flanges on the sides, and on top it gets a pair of brackets that will hold struts extending up to the bottom of the engine beds. Lots to go on these parts! 
In the background am printing more of the force chambers, and tomorrow I go get my second dose of the vaccine!   

[Don1966]

Awwww the smell of brass.........


 
Don

[propforward]

Wow - that is a wonderfully ornate part.

[crueby]

One ornate brass pump chamber all turned down to shape, being shown off by a happy shop elf just back from his shot

A look inside, showing the lip for the o ring seal and how it widens out down inside

The top needs to be drilled/tapped for the seal retaining ring, and there are more parts to add to the outside - brackets for the vertical supports, and the pipe flanges. I am planning on building check valves into the pipe flange extensions. But, that work needs to wait a day since I want to leave the mill set up at the proper setting for the bottom end bolt holes, and this was the last of the 2-1/4" brass rod that I had on hand, the new bar will be here tomorrow. So, in the meantime I've started bolting the printed pipework/housings together. Lots, and lots, and lots of tiny nuts to thread on...

[crueby]

Oh, and that logo on the sticker is from the state fairgrounds where they had one of the huge exhibition buildings set up as a vaccination site. Very efficient setup!

[cnr6400]

Pump parts look great! 
Congrats on the vaccination.