Chris's Holly Pumping Engine Build

[crueby]

Given that the loading will not be that high, could you 'pot' the bearing shells or housing in something that would setup while all the bearings were held in alignment with a straight piece of ground shafting? Sort of a variation of pouring Babbit bearings in-suti using the shaft as the alignment tool. 

-Doug

That's an interesting idea Doug. Bore the holes for the bearings slightly oversize and bed the bearings in JB Weld maybe? Hmmmm, that could fix any small alignment errors. The bearings have to be split since the crankshaft has wider sections at the flywheels (two, one between each bed frame) so the bearings could not be slipped over the ends. The flywheels will be 5 or 6 pounds each.


Great idea, will experiment with that! Thanks!!

[crueby]

Oh, and I found this picture of the engineer who designed the Holly engine going out for lunch....   

[crueby]

With the holes for the bearing cap bolts all drilled, time to move on to making the studs and nuts. I have small pattern 5-40 nuts, but they are not close enough to proper scale so I'll make my own. The studs are threaded both ends, and 2.4" long. One thing I've wanted to do for a while is set up for single-point threading on the Sherline, which does have a threading attachment set that adds gears outside the drive pulleys and a big crank. It works, but has some flaws - the gears are mounted to bearings on two flat plates which pivot on a screw at one end to accomodate the different size gears. The first plate clamps on a post around the leadscrew. All good thoughts, but the forces involved in turning the gears against the force of the cutter make the two pivot points want to move and let the gears (which have small teeth) skip. Also, the handwheel size requires that you either remove the motor or add a long extension which doesnt work out well. The only time I've given the threading set a real workout was on the Stanley engine, threading the engine block for the end caps. Worked, but did have some problems with the plates moving, nearly ruining the parts.

So, as I mentioned a couple weeks ago, I had picked up a second Sherline lathe short-bed/headstock without a motor to set up as a dedicated threading station. Actually, the way the price worked out, getting the motor/speed control in the base package was nearly the same price as buying the bare bed/headstock, so I got the base package and set the motor/speed control aside for spares for when I eventually wear one out - bound to happen given the amount of use I give them.
The threading attachment plates were modified to add an adjustment bolt that will keep the two from pivotting on the end screw once the gears are meshing. This bolt does not press in on the gears, just limits the movement to keep the plates from pushing apart. Also was going to add an adjustable post down to the table to keep the other pivot in place, but for now found a bit of bar stock in the bin to prop under it to see how it all works.

That seems to work great - adjust the plates/gears for proper mesh, then just hand-tighten the bolt and prop. Nothing has shifted a bit in the first pieces threaded, so happy with that. Here is the first of the 1/8" diameter studs threaded and test with a stock nut (too large across the flats, will make my own to scale size). It took extra passes on the first one, to work out the depth of cut, the rest should go quicker. I need 16 studs, threaded at each end.

[Don1966]

I was thinking on that second to last post. Using JB weld might be a good idea, but when you have weight pushing down on it it would move. If the bottom bearing sleeve is not a half shell but 3/4 shell then that might not happen. Just thinking out loud……


Thoughts Don

[crueby]

I wax’s think on that second to last post. Using JB weld might be a good idea, but when you have weight pushing down on it it would move. If the bottom bearing sleeve is not a half shell but 3/4 shell then that might not happen. Just thinking out loud……


Thoughts Don

Cant be anything more than a half shell, or I cant get it on the crankshaft with its wider sections around the flywheels and gear mount. Good point about the bearing moving or spinning. Maybe get it installed and bedded, then drill for a small brass pin to keep it from shifting?
 

[kvom]

My experience with threading studs indicated that testing in a tapped hole is needed as nuts are looser.

[crueby]

My experience with threading studs indicated that testing in a tapped hole is needed as nuts are looser.

Ah - had forgotten about that!  Just went and tested with a tapped hole, and I got lucky, the nut I used for testing must have been on the smaller end of the tolerances, the studs I have made so far worked fine. Both ends of these studs will have nuts on them, but ones that I am tapping vs commercial ones.
 

[crueby]

All the bearing block studs are threaded both ends, and about half of the nuts made from some .187 hex stock, they look a lot better than the commercial ones, which are thinner and .25 across the flats. One more batch of nuts to turn out and I can move on to boring the bearing holes.

[cnr6400]

 

It might be wise to store the finished studs and nuts in a female / squirrel-proof container. 

[crueby]

It might be wise to store the finished studs and nuts in a female / squirrel-proof container. 

 

[crueby]

And all 16 stud/nut sets complete

next will move on to boring the crankshaft bearing holes in the engine beds.   

[Kim]

That's a lot of work in that little pile!

The nuts sure do look nice though!

Kim

[crueby]

That's a lot of work in that little pile!

The nuts sure do look nice though!

Kim

Thanks Kim!   Good practice for the 12 rods that will connect the pump plungers to the crossheads later on. Same basic shape but bigger, they will go around the cranks to drive the pumps.

[steam guy willy]

Hi  those studs are looking the part with those smaller nuts ...over here in Blighty you can get one size smaller nut heads in the BA sizes from EKP ...this saves us a lot of work !!  good progress ...

Willy

[Swarf Maker]

Just one very, very minor observation Chris.  Nuts with each face chamfered are not usually encountered in this class of heavy engineering.  The face against the part being retained is usually flat.  Double chamfers are for general purpose nuts in the hardware store is my understanding.