Lady Stephanie Pumping Engine

[Michael S.]

Excellent work.
I enjoy watching the beam being created.

Michael

[springcrocus]

Thanks to everyone who is following this build.

Steam Chest

I have some ali-bronze that is a pig to silver-solder so I tend to use it up on jobs like these. I turned the gland housing first, then parted the billet off to length



This was followed by a fair bit of milling and one of those times where the power feed pays it's way.



Then it was set up against a backstop, the centre found and set as the reference followed by drilling all the bolt holes. Julius shows M2.5 bolts to hold it all together but I've opted to go with 8BA, mainly because I have some 8BA studding to use up. The four corners of the central waste section were also drilled and a 4mm slot drill used to cut away the middle. It's 14mm thick so I had to work from both sides, hence the backstop.



Earlier, I had made the blank for the steam chest cover and this was now drilled while the vice was set. I also drilled and reamed the central hole 8mm because I wanted to machine the outside on a mandrel. 8BA was chosen for the pipe flange screws as well.



Got to put it all together now.

Regards, Steve

[springcrocus]

Cylinder Assembley cont.

The cylinder top cap was made from another piece of bronze, along with the gland cap, but with dimensions that allow for compressing an "O" ring onto the piston rod.



The gland cap for the steam chest was also made, simple turning followed by forming the hex shape on the end. With short items like this I prefer to make a threaded mandrel on hexagon stock, screw on the item, then index it round in the vice. Holding the mandrel horizontally, the work self-tightens whereas holding the mandrel vertically allows the cutter to undo the workpiece.



The cap was screwed tightly into the steam chest (without the "O" ring) and the valve rod hole reamed 3mm right through.



Doing my own thing, rather than blindly following the drawing, I reduced a section of the exhaust pipe to 6.35mm diameter and threaded it 1/4" x 40 tpi. The steam chest base was drilled and tapped to suit and the flanged pipe screwed in tight to the shoulder. This does make the exhaust passage smaller than design but it's not supposed to be a high-revving steam engine, just a slow-speed pump.

The assembly was held in the vice, using timber to clamp on the curved surface, and the four flange holes drilled and tapped.



Then the base assembly was bolted onto the cylinder using five M2.5 stainless steel cap screws.





And a couple of pictures of it all assembled.





Regards, Steve

[Michael S.]

Hi Steve, the cylinder looks very elegant 👍.

Best regards, Michael

[springcrocus]

Thanks for your interest, Michael. 

Watt's Linkage Supports

Wanting a break from bronze and brass splinters, I decided to make the Watt's linkage supports next. As with the main pillars, I opted to make these smaller pillars and bases as separate components and then screw them together. For the tapered section, I parted them off to length, drilled & tapped each end M3 but with a decent centre at one end, then turned them using the compound slide.



Four pieces of 1.2mm steel made the top and bottom plates while some 3/8" x 1/8" and 3/8" x 3/16" covered the other sections, being faced to length the easy way here.



This is the collection of small parts that complete the assembly...



...and here they are on top of the canopy. Some M3 dome nuts pretty things up a bit.



I'm going to have a go at the beam next, should be fun.

Regards, Steve

[springcrocus]

Beam

In another thread, Jason drew my attention to the fact that Julius' dimensions are not always optimal and that the original beam was symmetrical. As drawn, the Watts linkage will oscillate between vertical and 4° backwards but a bit of simple trig shows that the horizontal movement at the limits is just under 2mm so I've made my beam with 101mm either side of centre. A few thou here or there will hardly be noticeable. I've also amended the length of the horizontal linkage arms by half a mil to compensate.



I thought I would have a go at making the beam from solid so the first thing to do was machine up a piece of 30mm x 10mm black bar to the outside dimensions. As usual, I'm not using bright mild steel because it will probably warp.



Then the two outer holes were drilled and reamed 6mm diameter and a central hole drilled 14mm diameter. I intend to silver-solder a boss in the central hole after I've milled away the inside to leave the central web.



A fixture was prepared with two M6 holes tapped at 202mm centres and the work bolted on with a packing washer under each end to lift it off the surface.



A 4mm carbide slot drill was used to rough out the inside...



...then I changed to a 3mm slot drill to extend the ends and finish the thickness of the web.



Now I need to find a way to machine those big radii. I don't have a CNC mill but my mate Wilf does although this might be a little large for his machine. A five foot diameter faceplate could come in handy, though.

Regards, Steve

[uuu]

I've got an X travel of 190mm, so we might be able to do the inside shaping in one go.  Outside - the ends would have to be done as a separate op.

Wilf

[Jasonb]

It can also be done with a DRO using either the PCD or ARC functions to give a series of holes say 0.5mm apart that can be plunge cut with a mill. Just enter the Y value at 30" or whatever is required as the ctr of the arc/PCD. Bit of hand work to complete

[springcrocus]

Beam cont.

I've been experimenting with some typical Heath-Robinson lash-ups to see if I could come up with a mechanical solution based on the kit available to me and had a certain amount of success and was able to mill the outside shape of the beam in two operations. I took pictures of a "proof of concept" practice piece but forgot to take any of the finished beam. I will write up something in the Tools section about this later.





However, the setup wasn't rigid enough to risk a 3mm slot drill with so reverted to using the DRO arc function to do the insides. I did some more roughing out with a 6mm end mill first, though, using the centre of the beam as the origin.



I then offset the "Y" axis to suit the 6mm end mill, set the radius at nominal plus half the cutter and 0.8mm for the max cut, i.e. step length, in the "X" axis giving over one hundred plunge cuts per half side. Swapped to a 3mm cutter for the final 25mm or so and finished all eight end sections. And forgot to take any pictures! Doh!

The boss was made with the bore undersize and then silver-soldered into place. I will ream that to size later.



Then it was left in the Phosphoric acid for an hour or so to clear the flux and blacken the inner surfaces.



Finally, a wipe-over with abrasive blocks to highlight the outer edges.



I can't do anything else with this yet because I've yet to make the central support assembly. Better make that the next job.

Regards, Steve

[crueby]

That came out well!!

[springcrocus]

Thanks Chris, I'm quite pleased with it as well. Two new-to-me techniques in one component.
Regards, Steve

[Kim]

There's a lot of work on that beam and It looks great! 

Kim

[springcrocus]

Thanks, Kim   

Beam Supports
I made the main section of the two beam supports from some 1" x 1/4" bright flat steel but haven't bothered to reduce the thickness to the specified 6mm, just rubbing up the outsides for a better finish. After squaring off and finishing to length, I used a 4mm end mill to clear away the lower section of each upstand in turn.



They were then stood on end and the two upper and two lower mounting holes drilled 2.5mm diameter for M3 and the bearing housing machined with a 6mm end mill.



The bearing retaining plates were made from 1/4" x 1/8" mild steel stock, drilling the three holes and hacksawing the two parts from the bar. Then they were screwed to the upstands, mounted in the vice and the sides milled away with a 16mm end mill. This ensures the parts stay in line.



The bearing blocks were made from some bronze offcuts in a similar manner to the crankshaft bearings covered earlier. The pivot pin was also made, a simple bar turned from 7/16" diameter stock bar and a couple of simple oil cups from some 1/4" dia brass



Finally the parts, along with the beam, were assembled in postion on the canopy.





Regards, Steve

[springcrocus]

Watt's Linkage Components

I've now completed the various components of the Watt's Linkage system and most of it is simple fabrication. I have made the lifting arms different to that depicted on the drawing, making a fixture to locate the components and silver-soldering them together. This keeps the spacing accurate.



The fancy-looking arms on the lower section of the Watt's linkage were drilled and reamed 5mm diameter, then mounted onto a mandrel on the rotary table using button-head screws, which have the correct outside diameter, to hold them down and the outside profile machined.



Another deviation from the drawing was the piston. I machined this from one of the  lovely cast iron billets that I purchased at the last Warwick MEX for 50p per piece (I wish I had bought more) with a pair of Viton "O" rings to act as piston rings. They are a bit tight in the cylinder at the moment and I might need to deepen the "O" ring grooves a little.



The 10mm diameter pump piston rod screws into the bottom of the cylinder piston and the 5mm cylinder piston rod screws into that from the other side. The drawing calls for an M10 thread and, as I have both taps and a die for M10 x 1, that's what I used. M10 x 1.5 seemed a bit too coarse and would probably throw it off line.



The other bits and pieces don't warrant a write-up but here are a couple of pictures of the various parts assembled. One in the upper position...



...and one in the lower position.



Now I need to sort out the valve gear.

Regards, Steve

[Dave Otto]

Lots of really nice work there Steve!
She is looking very nice!

Dave