Chris's Holly Pumping Engine Build

[crueby]

This is going to be an epic build!
 
Dave

Thanks Dave! 


For some of the smaller detail bits, I may be adding 3D printed parts - have one of the new Prusa Mk3 Original printers coming in a few days, seems like the technology, while still evolving, has gotten stable enough for me to dip my toe in that end of the pool. Handy for this kind of model, and will let me make some of the parts for the RC boats that have required making fiberglass/silicone molds for in the past. The vast majority of this engine will still be machined metal parts though!

[Don1966]

Yep doing it proud Dog......



 
Don

[cnr6400]

For casting the original full size hollow frame cores, I would expect that many chaplets would be needed along each core to support them, both under the core and at the sides. The moulders probably used several individual cores to be able to make shorter ones, easier to lift and less prone to breakage. (and they would likely put Shaky the jittery handed moulder on pattern cleaning or counting flasks, the day they were moulding frames.) 

Chaplets are still available in many shapes and sizes. Link to one local firm carrying them is below. You can often see the residual imprint of one face of the chaplet where it didn't melt right into the casting if you look at big or long castings on old engines.

http://smelko.com/?page_id=395

 

What is a chaplet and how is it used? Never heard that term before. Chiclet, yes, Chaplet, no.   

Hi Chris, Chaplets work by holding cores in sand moulds up where a core is too long and thin to just be supported at the ends, or too heavy for support at just one end. If you visualize the sand mould for the engine frame column, it would be a long rectangular trough in the sand. The core for the hollow centre would need to be supported along its' length in this trough. If there were raised areas of sand forming openings along the frame, the raised areas could support the core. But if no openings were possible for whatever strength or functional reasons, the core would have to be supported by chaplets. Think of a bunch of chaplets as doing the same job as a bunch of machinist jacks would if placed between the core and the mould face, the jacks would support the core leaving a wall gap for the iron. The iron flows in around the chaplets and melts them partly, and the chaplets become embedded permanently in the casting. After the iron solidifies the sand core is broken out of the centre of the frame casting.

Round faced chaplets as shown in the link in my original post mentioning chaplets could make excellent bar stools for shop elves though, so unless you really need them for a casting project , best to not have any on hand or the shop elves will take a seat and crack open some Elfensteiner stubbies.........

[crueby]

Thanks for the explanation CNR, that makes sense now. I suppose they could make them out of whatever material they are casting to blend in better too. Neat solution!

[crueby]

Got the mortises cut in all the end pads:

so the next step is to finish shaping the pads. Starting with the length - am using the mortise as a reference point for the outer size, since its important for the rail to be the right distance in from the base and top platform. Starting with one end, using a 1/4" tool bit blank on top of the vise to index from.


This way I could set the cutter height once, and cycle through all the parts. After that end is done for all the pads, will reset for the other three sides in turn. The pads also will get chamfered on the top edge, drilled for the mounting bolts, and the rails need to be thinned slightly in one dimension (with stress relief done first), and the mounting holes for the intermediate platform drilled through. So, lots to do on these lower frames still!

[cnr6400]

 

[Kim]

Sounds like a very repeatable process!  Which is good, because you'll have to repeat it a LOT of time! 
Kim

[crueby]

Sounds like a very repeatable process!  Which is good, because you'll have to repeat it a LOT of time! 
Kim

Jigs are well worth it for mass produced parts!

[crueby]

Today saw the pads taken down to thickness, then set up for drilling the holes in the corners. These holes have to match the holes in the base plates, and be aligned such that the rails come out in the right place. So, bunch of time with the plans and 3D model figuring out the offsets and double checking them, then made a little block that was screwed and loctited to the bottom of the drill guide that I made to drill the base plate holes. Here it is, with one of the pads set over it:

And flipped over to drill through the guide holes:


This will take care of the holes in the bottom pads - the top pads have a different pattern, so I need to make a drill guide plate for them too.

[Don1966]

 


‘
Don

[crueby]

‘
Don

Cheers Don!  These parts are getting lots of location marks and numbers to keep them all oriented right.

[Roger B]

Lots of interesting Fabrication       

[crueby]

Back in the shop this morning, more drilling of the mount holes in the bottom frame pads. Before moving on to the top pad holes, I bolted a set of rails to the base plates for a quick double-check set of measurements (all good so far)

So, started in drilling the holes in the top pads too. After that I need to pause and figure out the order of doing things for finishing the shaping on the pads and getting them permenantly attached to the rails.

The other new toy, I mean shop tool, that arrived a few days ago is my new 3D printer (Prusa Original Mk3+) . Got it assembled the last couple of days, and tested out with their sample prints. All good once I got the two fan plugs in the right places (the self-test caught that fortunately). Then played around with the slicing software to figure out how to get obkects from Fusion over to be printed. I started out with one of the big water intake pipe elbows (its about 60 degrees of turn) since it has overhangs and such, which take extra supports to print. Here is the print underway:

and finished, ready to remove from the printer and snap off the scaffolding that it uses to hold the overhang (since it cant start the bottom of that flange in mid-air). That pipe is about two inches tall.


Came out pretty good, a little light sanding/filling to get rid of the slight texture on the curved surface. I'm thinking of using printed parts for things like this, that would be really tough to machine without CNC - some of the pipes are round, some oval, as well as for some of the smaller detail parts. Main use will be with the RC model submarines.

[Roger B]

I am maybe a Luddite about the new technologies (or maybe I really just don't have the time ATM) but that to me is impressive     

[crueby]

I am maybe a Luddite about the new technologies (or maybe I really just don't have the time ATM) but that to me is impressive 

Me too in some ways. For decades I worked on computers all day, and didn't want one in the house so I could get away from the keyboard!  The printers have come a long way, much better out of the box, and for the current projects I thought I would try one.