Chris's Holly Pumping Engine Build

[crueby]

The pump rods are all threaded at both ends, and I made up another batch of a few dozen of the nuts - needed some for the rods, know that more will be needed later for other parts...

[cnr6400]

Looks like you had some hexagon therapy Chris !   

[crueby]

Looks like you had some hexagon therapy Chris ! 

Nice easy parts, a nice change!  This afternoon I started splitting the bearings with a jewelers saw, three of four cut. After marking both sides to ensure the halves stay together - learned that one the hard way on an engine!  The sawblade is only 14 thou thick so very little kerf loss. With the first three set in place its looking like the horizontal alignment is spot on, might need just a thin shim under one bed, won't know for sure till everything is bolted down quite pleased so far!

[crueby]

As mentioned, the crankshaft bearings were split with a jewelers saw with a fine blade, about 12 thou thick

Got them test fit in the engine beds, checking with a straightedge showed that the middle bed needed to come up just a bit to line them all up (horzontally they lined up great). So, put in a couple thin (5 thou) bits of shim stock under the corners of the middle engine bed and it all went right into line. 

Here they are with the caps set in place. The bearings are still a little bit of a snug sliding fit on the shaft, so after the beds are all bolted down permanently and the crank webs are on, I'll run it in with some fine lapping compound.

The obligatory family shot...

Before bolting down the end engine beds, I wanted to make the catwalk brackets that sit between the beds, easier to get the screws in when they are separate. Started with some rectangular bar, and milled recesses on both sides to form the flanges

Here the bar is with both sides recessed, ready to cut them apart into the individual brackets

The ends were then milled off to smooth out the saw marks and make them all the same length, and the mounting holes were drilled in the short face, holes drilled/tapped in the long face for screwing down the floor plates to.

The bottom edges were milled at an angle to form the rest of the bracket, used a piece of wood notched at the angle to hold them all the same (making 14 of them)

A spritz of paint and screwed them in place on the engine beds - the floor plates will be added later on. There are still quite a few longer brackets to make that will go around the outside of the engine beds for the main catwalk at that level (there will be two more catwalk levels up above). Those longer brackets get cutouts in the center, and have three mounting holes rather than two.

Next steps? Getting the other two engine beds and vertical pump supports bolted in, making the crank webs, then will start in on the flywheels - two of them, 7.5" diameter by 1/2" thick at the rims, with taper lock centers. I have a couple of large cast bronze flywheels from Martin that I am going to use. Having them flywheels will make it a lot easier to spin things to lap in the bearings. Also, I need to make the bevel gears for the lay shaft, one goes on next to the HP end flywheel, along with the gear case. Then on to the rest of the catwalk... Long way to go just to finish up this level of the engine!

[RReid]

It gets awfully hard to think of new superlatives to use when commenting on your work. Just awesome.

[Kim]

Lot of nice little brackets there, Chris!  Love how you did the production line of them then cut them apart. 
And they use two screws per bracket to attach them?

Kim

[crueby]

Lot of nice little brackets there, Chris!  Love how you did the production line of them then cut them apart. 
And they use two screws per bracket to attach them?

Kim

Thanks guys! Much easier to mill the shapes in as one long bar before cutting apart, lot less fiddling about with clamping each one. Without stress relieving, the bar would warp in both directions as the first side is cut.

Kim, these brackets have two screws each - the later ones have a much longer and taller profile, so there is a third screw at the bottom end on those. This picture shows the brackets at the upper two levels - for all the levels and things they attach to, the plans show a couple dozen variations on the theme:



I was just playing around in Fusion and Gearotic Motion (gear calc app) to work out the sizes for the lay shaft bevel gears to see how many teeth and angles to use given the size gear cutters I have. Works out that at Module 0.6, the large gears are 54 tooth, small are 12, with a 77 degree bevel angle combination. While looking at the gear housing at the lower end, I also realized that it needs to be made and installed with the crankshaft as well as the gear, since the housing is one piece all the way around the gear/shaft.  The housing includes the bearing mount for the take-off shaft that runs up to the lay shaft....

[cnr6400]

Looks great Chris! glad to hear the bearings lined up so close. Lot of work just in the catwalk supports. 

[Kim]

That's pretty amazing, Chris.  I see a lot of brackets in your future! 
Kim

[crueby]

That's pretty amazing, Chris.  I see a lot of brackets in your future! 
Kim

Yeah.     At least they are not crawler tracks this time! 

[crueby]

This morning saw the two outside engine beds and vertical column sets installed for good (I hope) - lots of screws in hard to reach spots, but its looking like a proper forest in there now!

The four pump rods on each plunger can be screwed in from the top, so I didn't have to get fingers in there too, I did put in a little oil on each plunger's o-ring while it was accessible though.The crankshaft holes are all lining up well - put a straightedge down the length and could not see any light through, so it should all be close enough to lap in the bearings.Next I think I'll start on the crank webs, have been coming up with the schemes to hold and turn the flywheels and their hubs too....

[crueby]

So this morning I put together the crankshaft web 'kit' - rough cut lengths of the flat and round bar needed for the three webs/cranks.


For the center crank, two flat bar pieces were lined up and screwed together to keep them in alignment for the boring operations. The two screw holes will get plugged later - well worth it to avoid any movement. The crank pin hole was bored at one end, and started boring out the crank shaft hole at the other - the two holes are 1.031" apart to match the scaled down 33" offset/66" throw on the pistons.

Since the large hole needs to match the diameter of the existing crankshaft, and measuring the ID of a hole can be tricky, I took a page from others here (sorry, I forget who I learned this one from - you know who you are, think I've seen it on a couple threads) and turned a step gauge block. The largest step measures the same as the center boss on the crankshaft, and the next three steps are one thou smaller each. That way I could get it close and fine tune the last couple passes till the gauge would just slide in, without having to remove the block from the vise since the crankshaft is too long to trial fit it in place. Here it is almost there, one more step to go:


Another pass with the boring head, set almost one more tick in, and it just slides into place:

Moment of truth - took it out of the mill and test fit on the crankshaft, it just slides onto the center boss - snug enough that it stays in place but just loose enough not to bind up and jam. Should be perfect for assembling with loctite and taper pins.

And that seems like a perfect place to walk away for the day and bask in the accomplishment, do any more and I risk swarfing it up from getting a little tired. Tomorrow I can turn the crank pin, which will be full diameter in the center and step down to be a snug fit in the holes in the webs. It will also be loctited/taper-pinned into place. The original had a keyway on the main shaft, and the crank pin had a square end to go into the web. The taper pins and loctite should do the same job for the model.

[cnr6400]

 

[Kim]

  Great start on the crank web, Chris.  I'm a big believer in those sliding go/no-go gauges.   They work a treat!   

Kim

[crueby]

Got the crankpin turned to fit the webs,


Then filled the screw holes with some JB Kwikweld - left the epoxy standing proud, after it had set up trimmed it flush with a sharp knife. Also sanded the corners. Here is a test fit on the model

All looking good, it clears the engine beds when turning, so I got the webs/pin all loctited up, careful to wipe off any excess so it doesn't want to stick to the bearings later.


I'll let that set up overnight, tomorrow can drill/ream for the taper pins. I'll get started on the end crank webs, but I can't install those till the flywheels and the gear/gearbox are made. Given the tight quarters for the gearbox mounting, I am thinking that I need to change the box to a top/bottom two-piece assembly since there will be no room to get in there to put in the mounting screws with the flywheel in place next to it. I dont have a scale-sized apprentice to hang on a rope by his ankles like they probably did in real life!