An Unusual Steam Engine from Live steam magazine Oct 1977

[va4ngo]

Work on this engine started some time ago (more than 15 years) and I had only had made the piston as a trial when I had no other projects underway.
After a 15 year rest and being inspired by this forum, I once again commenced work on the project.

All work is now being carried out on the following equipment

Hercus ATM 260 lathe ( ex school lathe) ( No milling attachment)
Waldown Drill press probably post war era with large 4" machine vise
Drive plate for lathe with many 6mm holes for mounting (I dont yet own a faceplate)
Home made vernier height gauge
Home made Tailstick dieholder
Home made centre finder
Vice, hand tools and files

This engine is based on drawings in an old book, "The Steam Engine" by Robert Scott Burn published in London in 1854, and published in live steam magazine in October 1977, by Robert S Hedin.
The engine is unusual in that it has one piston rotating and oscillating in a rectangular cylinder. The engine comprises 4 conrods, several links
and a sliding rod valve inside a housing. Most parts are brass with the baseplate made from 1/4" aluminium. Piston is steel and Special screws are made from Stainless steel.

Here is shown the baseplate simply cut with a hacksaw from a flat Aluminium plate.
The base was then squared in the lathe, mounting holes were marked then holes drilled in the drill press.

In the background is the piston with exhaust openings and also a number of brass spacers.

 

[zeeprogrammer]

I'd like to know more about this engine. Any pics?

 

[va4ngo]

Here I am about make three parts from round stock, the valve bracket, flywheel bearing and valve block
The parts were marked out and placed in three jaw. Parting tool was used to set location of all shoulders using a vernier caliper depth stop marking off from the parting tool and end of job
After marking the part is set up in four jaw for squaring off. I did not have any rectangular bar stock hence the reason for making from round stock. In retrospect, I would try to buy rectangular stock as it took more than an hour to square off the round stock.

 

[va4ngo]

Here the part has been squared off in the 4 jaw and ready for making the valve bracket in next step

 

[va4ngo]

Here the valve bracket is marked out and roughed out using a hacksaw set up in the vice.
After filing to size, the valve bracket is complete.

All my marking out is done with a home made vernier height gauge which I made some 30 years ago.
At that time, I had access to a milling attachment for the hercus lathe Unfortunately I no longer have a milling attachment. The height gauge has had very little use until now.
This forum has certainly encouraged and inspired me to commence work on engines again.

The height gauge is made from mild steel and requires only a small modification to the vernier, a very small notch used to hold the marking part of gauge.

 

[va4ngo]

The 2 lever arms were made marked off on the end of a round rod, drilled in drill press and filed to shape and eventually parted to 0.06" thickness in the 3 jaw.

Here you can also see the home made vernier height gauge in use. I have found this to be a very useful item for reasonably accurate measurement and is well worth the effort to build.

 

[va4ngo]

Here is the inlet valve connnection also a simple turning job also from the rectangular (forgot this piece in original so had to square off another piece_ very time consuming)

Zee I dont have any completed pictures as this is a works in progress even though well advanced)
Next the flywheel bearing is cut from the rectangular block, bearing position marked, drilled for the bearing housing and a rod pressed and loctited in to place.
The hole for the bearing will be added later. I dont have a build instruction for this engine.

Then mounted on baseplate. The two mounting holes for the crankshaft bearing were badly misaligned so I relocated the two holes transversely instead of longitudinally as there was ample material in place to do this. I do not like making a part twice so where I can, I will salvage parts and rework as necessary to fully make good a damaged part.

 

[va4ngo]

Next I am making the valve body. Originally started making this on Drive plate and got so carried away that I drilled right through body (after having reamed very accurately for the valve body) but was able to salvage part by inserting a brass rod and parting the excess away. (refer 2nd photo where round rod is protruding from square body)

Next (3rd photo) I milled the slot for steam passages. This was done in drill press by progressively moving the part along a guide in the drill press, clamping down and using a very small end mill to 1.5mm depth. It took about 15 progressive movements of part, reclamping and remilling to complete the slot. The two guides are at rear of valve block. I am uncertain how well this will allow steam to flow along slot as the slot is rough on edges of milled slot. I can clean up with a file on end but suspect this will be very difficult as I will be filing in to a blind hole.

The valve block is now almost completed, just requires mounting and exhaust holes. The valve was a simple turning job in 3 jaw and is shown fitted into valve body with top cover also fitted. I made a cosmetic change to top cover and secured it with 4 screws instead of silver solder.

The last photo shows the valve fitted to the the valve block temporarily. Note the use of small pins used to hold inlet connection in place. These pins are stainless steel welding rod 1.6mm diameter which coincidentally is the correct size for tapping a 2mm hole in valve body. The inlet holes will be opened up after tapping the holes

All the parts to date are of Brass. Baseplate is 1/4" aluminium. Special screws for lever arms and links are being made from stainless steel turned in the lathe and tapped 2mm and are a simple turning and threading job using the home made die holder held in the tailstock of the lathe with gentle hand feel for threading I did not use any coolant or Rocol when threading the 2mm screws.

 

[va4ngo]

This part was required for the end of valve.
Marked out and firstly drilled and tapped a M2 thread then drilled the cross hole and finally filed to shape.

Small parts are hard on the eyes but great to see mounting up

Here you see the name of one of our Australian abrasive suppliers and a comparison with a 5 cent piece (I think you call them a dime? )

 

[va4ngo]

The eccentric strap was made in both the Drive plate and 4 jaw.
First the 1/2" hole was drilled in 4 jaw then the smaller hole (for a change only) in the driveplate.

Then filing in vice and finish

 

[va4ngo]

Here is the progress on the valve/ eccentric strap sub assembly and another view with the valve block (valve housing) in place.

All items are made of brass except special screws which I made from 3mm Stainless steel rod and threaded M2 . Nuts are purchased and are Nickel plated brass.

I pay very little for all my materials and spend most sunday mornings at a local flea market where I have purchased most of my brass, aluminium and Stainless steel plus workshop engineering tools including vernier, DTI, adjustable height gauge, taps and die sets (I made a vernier height gauge to attach to vernier)

I think I would like to build a beam engine next off. Any suggestions for a good looking beam.

Would probably prefer to make from bar stock but would consider a n engine from castings if it looked very good and not too costly. I live in Australia.

 

[Bill Mc]

Hi Phil - I am following your posts with much anticipation wondering what the final outcome of this engine will look like. Keep up the good work and the fine photos. It was 28 degrees F. here at Baxter Ontario Canada and you are just entering into summer arghhhh. - Billmc

 

[4wheels]

Hi again Phil,
I too will be keenly following this build of yours as well as the previous build.
Cheers,

 

[zeeprogrammer]

Interesting build Phil. Thanks for the pics. Keep them coming!

 

[ozzie46]

Great work.

In the interest of accuracy, a 5 cents Is a "nickle" and 10 cents is a "dime" :hDe: :hDe: ;D

Ron

 

[va4ngo]

Picture 1
The Rectangular cylinder frame (there are two verticals) is the next item to be made, This is made from 1/8" x 3/4" x 4 1/4" long brass plate (By the way, I am using converted metric dimensions as I have a Metric Lathe). I cut this from a wider piece using a hacksaw to rough out, squared up in the 4-way toolpost holder (I brought the face of toolpost up to the drive plate to ensure squareness) then squared off the end with an end mill.
To perform this operation, the edges of brass plate were checked for parallelism with the ways by using the dial indicator and moving the saddle along the bed. The brass plate was then adjusted until parallel using dial test indicator.

Picture 2
The 4 connecting rods are also made from 1/8" brass x 3/8" wide x 2/7/8" long. The hole spacings are required to be identical so using the above method and milling to identical length, I proceeded to drill a 1.6mm hole in each end using a jig on the drill press. This simply comprised a guide along which the con rods rested against an end. After drilling one hole, the item was simply slid along the required distance (2.50") and another rest was placed there. All parts were clamped to table. Holes in Rod ends were then drilled to appropriate sizes.

Picture 3
Two of the connecting rods have a small hole and two a larger hole. As the rods were identical length, I made up a stepped locating pin to be a snug fit in holes and then began the long procedure of filing the con rods to shape in the vise.

Picture 4
All rods will be filed together.
Beginning the filing of all 4 connecting rods. The stepped pin can be seen at right end of photo. A pin is fitted to each end

 

[va4ngo]

The following three pictures are out of order

The Cylinder cover plates are also made of 1/8" brass sheet

Marked out 1 part only then drilled with a 1.6mm drill ( I use this size drill because I also have 1.6mm stainless steel welding rod which makes a neat fit pin for locating parts together. The second cover plate was drilled using the first as a template and graduall y fitting the 1.6mm stainless weld rod pins as I drilled each hole ( only used 4 pins)
The part was then squared off in the 4 way tool post and then progressed to finishing filing

The three large holes in cover plate are what will be a 0.265" wide x 2.50" radius slot to accomodate the crankshaft as a loose fit.
The slots in cover plates were separated and finished separately

 

[Krown Kustoms]

looks good so far.
-B-

 

[va4ngo]

The eccentric is a little more interesing so will desribe in more detail.
Material used is Mild steel I dont know what grade I used other than it machines easily.
This is to mate to an already made part, the Eccentric Strap. I always build the part with the hole rather than the part with an outside machined shaft. It is far easier to match a shaft to a hole than a hole to a shaft.

In the 3 jaw chuck without the need to centre drill, I turned a 1 1/4" long shaft to 12.64mm (approx 1/2") diameter for approximately 3mm along the end, but checked before reaching this dimension with the brass eccentric strap hole to ensure a good running fit. The hole in eccentric requires a 0.01mm clearance. First I turned the diameter to appropriate size, checked for fit on the diameter then continued and checked the fit for correct width with 0.01mm clearance end play.
The part was then removed from the 3 jaw for marking out
This is shown in photos

 

[va4ngo]

The unfinished part was transferred to a v block ready to mark out the eccentric.
Here is the method I used as described in the book " The Anmateurs Lathe" I find this method very easy and reasonably accurate.

The part was set up in V blocks and secured by a sliding clamp. The end was measured at 12.64mm with a vernier.

Photo 1
Next set up the vernier height gauge on top of the part to be marked and set the dial indicator to zero.
We now require to find the centre of the bar so come down half the diameter of the part (which was 12.64mm) so the amount to come down is 6.32mm and scribe a line around the end and sides of the shaft.

Photo 2
Next rotate the block 90 degrees and support on a set of parallels as shown to give clearance for the sliding clamp
Again place the vernier height gauge on top of part and set vernier height gauge to zero.

We again need to find the centre so come down the same amount i.e. 6.32mm which is half the diameter of bar. Scribe a line across the end of bar and set vernier height gauge to zero

Photo 3
We can now mark the two eccentric holes which in this case are 3mm above and 2mm below the line.
Marking out is now complete, just centre punch all the holes, the side hole (which I failed to do in this set up so I had to re set the part in v block later. This was easily done as I had some witness marks to go by ( remember the marks around ends and sides)

Photo 4
The part is now transferred to 4 jaw and off set using a centre finder (I have a home made one for this)
I drilled and tapped the holes on the lathe using tap held in tailstock chuck.
The part was then parted and finished. Here is it is seen mated with the eccenttric strap