Sub Base

Drawing #2

Start by cutting a piece of 6mm aluminium a little larger than the 110mm required, locate the middle and dot punch. Mark out a 110mm circle with a pair of dividers, roughly mark 45degree lines and saw off the corners.

Clamp the plate to the mill table with some packing underneath then proceed to drill the four M3 clearance holes and the four 4.0mm holes which will be used to mount the engine to a wooden display base. Then with an 8.0mm dia milling cutter counterbore the 4.0mm holes 3mm deep and also cut a flat bottomed hole 2.0mm deep in the middle of the plate to locate the valve spring into. If you have a larger spring then make the hole to suit. Once removed from the mill table the underside can have the M3 clearance holes countersunk so your screw heads sit just below the surface.

Screw a piece of ply or MDF to the lathe faceplate of if you have a large enough 4jaw then the board can be held in that, use the tailstock centre in the dot punch mark to hold the plate to the board and then screw it on through the 4.0mm holes and turn the outside down to 110mm diamater.

Blue the plate in a couple of places and then offer up the base using a couple of screws in the M3 holes to line things up and scribe on its diameter.

Swing the topslide right round and set to about 4degrees then taper the edge of the plate until the cut runs out where the scribe marks are.

The last turning job is to add the decorative moulding to the edge which can be done by grinding up a small HSS form tool.

Finally back to the mill, pop two drill bits into the 4.0mm holes and locate them against one of the tee slots then locate the middle of the plate. Using the 8.0mm cutter again cut the other half of the exhaust passage 3.0mm deep

And a quick picture of the two parts together, I will give details of the spring later.

J

Vic, you obviously missed the video of the engine running that I posted the other day so here it is again.

As they say Beauty is in the eye of the beholder. I mentioned in the intro that I was attempting to replicate a specific engine that was originally made with castings so there will always be more work involved than if you were making a freelance barstock engine where you are able to do what you like.

I did not find anything too difficult about building it but that does obviously depend on the abilities of the individual and made it in two weeks of weekends and the odd evening. I would say it is easier than the Jowitt which I did a similar build thread for and quite a few of those have been made and are sucessfully running.

My plans can be used as a guide and built as anyone wants, if they feel one of the machining processes is difficult or not to their liking then it can be left off or adapted to suit so long as the basic workings of the design are retained. For example the base and sub-base would work just as well like this, not to my own tastes but may be to others but certainly less work involved.

Maybe I should repeat what I said at the start of the Jowitt build:

"Some of the parts could be simplified if you want to have a go but don't feel confident of things like shaping the cylinder or the angled cuts to the base and I will point these out as I go along. There are also other ways that most parts could be made, I have used what I have but feel free to ask if you don't have some of the equipment that I show"

J

Edited By JasonB on 15/06/2017 12:50:49

Next put your parting tool in the toolpost, set the front edge to touch the work and zero the cross slide dial. Then with the topslide touch the edge of the tool against the end of the cylinder, retract and move half the width of the cutter towards the headstocjk and then zero the topslide handwheel. This will make it easy to set the spacing of the fins as they are all dimentioned to their ctr from the top of the cylinder OD.

First make a central cut on each 5.5mm deep.

Then increase the width of the slots to 4mm by taking a equal cut off each side of the first grooves.

Then swing the topslide around to 5degrees and cut the taper down one side of each fin. Swing to 5deg the other side of zero and make a similar set of cuts down the opposite sides.

Grind up a 4mm square HSS tool bit to a half round profile and then round out the bottoms of the grooves, a slow speed will be needed to avoid chatter.

Then with a file the external corners can all be rounded over whith the lathe running.

Remove the tailstock and trim the spigot back to its final 5.0mm length.

With the largest part of the lower cylinder uppermost mill it back flush with the edge of the fins or just a fraction proud. Use a nice sharp cutter as we want a good finish here to save excessive lapping later on.

Centre up the port face and drill two 4.0mm holes 10mm each side of ctr into the bore, then another four holes will remove most of the material from the inlet passage. Finish up by cleaning out the slot with a 4.0mm milling cutter.

The cylinder can then be held bottom up on the rotary table and the two sides of the port machined as was done to the base.

Then again like the base round the rest to 42mm dia

Then add the four holes but this time thay are tapped M3.

Finally for now the five M2.5 hole scan be drilled and tapped in the top but make sure you drill them in the right place unlike me :-[ the one above the port face should be left out.

J

Bearing Support

Drawing #4

I mentioned at the start that there were two pieces that are silver soldered fabrications, this is one of them and it is the one that if you are not able to silver soilder too well could probably be done by machining the vertical part into a "+" section and then tap this top and bottom for a couple of M2 CSK fixings each end. Though it would also be a good thing to get the hang of silver soldering on as there is not much material in it and if the worse came to the worse it could be melted apart, cleaned up and another go at soldering attempted.

I have shown the finished sizes on the drawing but strongly suggest that the top piece is made of something thicker than 3mm material and also left ovesize in the other two directions. It is unlikely that you could solder it all in exactly the right position but by leaving the top oversize it can me treated like a casting and machined exactly right once soldered.

So make a start on the lower ring. Chuck a piece of 45 or 50mm dia bar, turn down a short length to 42mm dia, face the end and then drill and bore out to a nice snug fit on the 28mm spigot left on teh top of the cylinder. Saw or part this off and then face back to the finished 5mm thickness

For the curved part of the upright I used a short length of scaffold pole skimmed inside and out to clean it up and then faced both ends to bring it to 32mm long. It could be cut from solid or even bent up from some 3mm flat, the exact curve is not really that critical.

The cross shape is made with a halving joint so mill a 5mm slot half way up.

Then mark out a pleasing shape. I drilled 5mm at the top to leave a nice fillet shape and then drew the two larger curves by scribing around a roll of masking tape. Saw and file to your chosen design.

The other part of the cross is cut from a bit of 5mm flat plate and has the other half of the having joint milled in it a 3mm wide. Finally cut and file to shape. I would suggest the face that the valve rod guide screws to is also left overside at this stage.

Another bit of the 5mm stock forms the top plate, these are the 4 parts prior to soldering.

Give them a good coat of HT5 or Tenacity5 flux and place on the hearth, a couple of bits of scrap metal can be used to help steady things. Put a bend in your solder rod before starting to heat as it makes it easier to apply the first bit of solder under the top plate then chase the heat down with the flame watching the solder flow as you go adding more as needed.

Once cooled give the part a soak in your chosen pickle I tend to use brick cleaner now as it shifts all the black scale from soldering steel as well as the HT5 flux.

The part can now be held on the mill either using a chuck or clamped to the table. If holding in a small chuck as I have shown add a clamp or two to hold it down because the leverage from milling the top can pull it about a bit and result in a chip to a nice new milling cutter With it held in place locate the centre of the hole and from there the 4 sides of the top can be machined to the drawing dimentions and the two M2.5 holes drilled & tapped. Then mill the top down until the 40mm height is reached.

Now with the bracket upside down in the mill vice locate centre and drill the five M3 clearance holes on as 35mm PCD, support the overhanging edge so it does not move under pressure from the drill.

Holding by the round ring and with the long side of the top on the flat of the vice the surface for the valve rod guide can be milled back until the cutter just skims the edge of the ring which will put the surface 21mm from ctr. Don't mill right upto the top plate but feather out the cuts and afterwards file to a pleasing radius. The two M2 holes can also be drilled and tapped at this time to complete another part.

J

Piston and Associated Parts

Drawing #5

Before starting on the piston it is best to hone the cylinder, this can be done quite easily with one of the cheap brake cylinder hones. I run these in the bench drill at about 750rpm and just move the cylinder gently up and down making sure not to let the stones stick out too far and risk a bell mouth end, a little paraffin will help stop the stones clogging.

The piston will come out of a length of 25mm cast iron bar, face it off then turn the outside until it just enters the cylinder bore. Check against both ends of the bore, if one is smaller then use the hone some more to remove any taper. Once you have a push fit into the cylinder stop working on the outside and bore the inside followed by drilling and tapping for the M3 thread.

Saw or part off the piston and then face off to 20.5mm finished length being careful not to distort or crush the now hollow piston. Face off and tap a bit of say 12mm bar to take an M3 screw and this can be used as a mandrel to hold the piston while it is lapped into the bore. This is easily done at a slow speed with a small amount of 1000g silicon carbide powder and a liberal amount of oil. Just work the cylinder onto the piston from the top until it is a close but friction free fit. Clean off all traces of SiC powder.

The lug for the gudgeon pin can first have the end reduced down to 3mm and then be threaded M3

Then mill it to a square section if you have not started with square bar. This can then be cut off the main bar and milled to length and a 3mm slot cut into it.

Followed by the drilled and reamed cross hole after which the end can be rounded off by filing or machining.

The gudgeon pin is a simple turning job. Onec done blue the end, put it in teh hole and mark off the position of the split pin hole. Then drill for a 0.8mm (3/32&quot split pin.

This pic shows the finished parts along with the conrod which is still to be descibed.

J

Cam Disc

Drawing #7

I machined this on the other end of the bit of 40mm dia steel that the crank came out of.

Start by facing the end and then turn the 12mm dia x 6mm long spigot followed by drilling and reaming 6.0mm

The cam can be formed in a number of ways: milling, turning in the 4-jaw or even filing to the template included on the drawing. I opted to mill it using the rotary table as follows

– centre the rotary table under the spindle and zero the dials or DRO, lock y axis
– hold work in chuck , put a 6mm rod in the collet chuck and bring down into the hole
– move table 11mm in the x plane allowing the chuck to slide along the rotary table
– Bolt chuck to R/T
– Fit a cutter into the collet chuck and work your way in from the edge rotating the work on the table until the x axis is 25mm plus half your cutter dia.

Saw off from the rest of the bar and then hold by the spigot in the 3-jaw, face back to 3.5mm thick and then take a further 0.5mm cut but stop to leave the 8mm raised area in the middle which will make sure the cam only contacts the bearing inner race.

You could mill the two 10mm radius corners that blend the arc into the main diameter but I just opted to file it to shape.

Final job is to drill and tap for a M3 grub screw.

J

Chimney

Drawing #9

The main chimney is a simple job from 10mm OD aluminium tube, thread one end M10x1.0 for a length of 22mm. Face to length and form the 9mm dia spigot on the other end. I used slightly larger OD tube so had to machine it down to overall diameter.

The base is just some 12mm stock drilled to 9.0mm and tapped M10x1.0 with the upper edge rounded off.

The top ring can be turned on the end of some bar and if you put a parting cut part way through so the bead can be easily shaped the drill will part off the work as it brakes through.

The parts can be assembled with a drop of Loctite 648 to hold the ring in place, make sure you have no more than 2mm of thread sticking out the bottom otherwise the exhaust passage in the base will be restricted.

And a quick test fit to round off this installment.

J

Conrod

Drawing #10

This could be turned from a length of 10mm aluminium 6082 but I had a lot of 1/2" (12.7mm) so used that.

Cut off a piece about 20mm longer than needed, face each end and put in a small size 0 ctr drill hole, reduce one end to 8mm dia and the other to 10mm if using larger stock.

Now holding the rod in a mill vice the two holes can be drilled and reamed and the ends flattened off.

Back to the lathe hold the 10mm end in a collet or 3-jaw and offset the tailstock to form the taper, I used a small live ctr in a boring head to get the offset rather than disturb the setting. You could also set the topslide to an angle if prefered. Do the final cut swith either a small HSS tool with a rounded end or an insert tool like I used in the photo to give the fillet where the round rod joins the flat ends. Do take it easy as the rod is getting quite thin at this stage but will be nice and light.

The two bearings are simple turning jobs from a bit of bronze bar with reamed holes. I find the mill vice is quite good for pressing them in, use a spacer on the big end so the bearing can protrude evenly both sides. If your fit is a bit loose then high temp Loctite such as 648 should hold the bearings in place.

This is the finished rod together with the Gudgeon pin block and piston described earlier

That's another bit off the list, hopefully you won't have to wait so long for the next installment

J

Shutter parts

Drawing No11

Shutter Rod Guide

I did not have any 5mm thick brass so thinned down the end of a piece of 1/4" material and then drilled the 2.0mm hole at least 31mm deep.

With the work now on it's side the recess was milled out with a 6.0mm cutter to give the required 3.0mm radius to the internal corners.

After cutting off from the parent bar the back face is milled to finished size and then the 1.0mm step cut from the lower end.

Turning the part the other way up the larger recess can be milled out, the two 2.0mm holes drilled and then countersunk then finish off by filing the 2.5mm radius around the upper screw hole.

Shutter

This starts life as a Stanley knife blade or "utility" knife as I think our American members call them. It is best to shape the knife blade after the steel block has been soldered on just in case it moves about during silver soldering. Also worth leaving te block a bit long to start with so just make teh 5×8 dims to finished size then solder.

The blade can then be roughly trimmed to size making sure the edges are true to the edges of the block. With the rod guide screwed into place machine a point onto some 2.0mm rod and pass that through the guide and use the rod as a scriber to mark the position of the M2 hole.

The hole can now be drilled and then tapped M2 and the block rounded over. I would suggest leaving the final shaping of the shutter until it is mounted on it's rod.

Shutter Rod

This is quite a simple job so no photos, face the rod to length and cut the M2 thread on each end to the lengths required.

This shot shows the finished part , the fork and cam follower roller will be covered next time.

J

Very Little, I'll try and get it up in the next few days