Burrell Single Crank Compound Traction Engines - 4" Scale

[jadge]

Yep, been sorting out some remaining work issues and handing over some parts I've made for a glider restoration. Also making sure I've got everything ready for a trip up north with the glider soon. I can confirm that the parts shown will be available for inspection at SCMTEG in a few weeks. 

Andrew

[jadge]

Having made the crosshead and slidebars I'm keen to get on and start machining the cylinder. As a precursor I decided to update my 3D CAD model. Big mistake! I've spent ages correcting errors and accounting for the vagaries of the casting. On the drawings the cylinder and other parts are shown leaning back slightly to the crankshaft, specified variously as an offset or an angle. At the start I decided to bin this idea as it would make machining the cylinder unecessarily complicated. Having modelled the cylinder to get the vertical centreline of the engine in line with the crankshaft two problems arose. The flange on the bottom of the cylinder was only 1/4" thick. It would be strong enough, but is much thinner than prototype and wouldn't allow the flange to sit above any sensible thickness of cladding. The second problem was that the outer slidebar support casting was unusable - too tall. So I tweaked the cylinder model to lean back by half a degree. All the problems went away! The flange on the cylinder base is now about 1/2" thick and the support casting is right. On reflection it won't make the cylinder more difficult to machine. I can machine everything square and then at the final stage of machining the bottom of the flange just tilt the whole cylinder a bit. On the fullsize engine the cylinder tilts back slightly. So presumably the designer had the same issues of getting the cylinder to line up with the crankshaft.

On other forums there has been a discussion on what thickness of gasket to use. Although my steel boiler is made from hot extruded tube the diameter only varies by about 4 thou around the circumference. Most advice was to use a 3mm or so gasket. That seems very thick to me; I think I should be able to get away with a 1/32" gasket. To check the fit of the flange on the boiler I 3D printed just the flange from my CAD model:



I can get a 5 thou feeler gauge in between the flange and boiler in places, but generally the flange is a very good fit. More experimentation is needed, but this is a good starting point.

Some years ago I bought a face mill for the horizontal milling machine. This will be useful for roughing out the cylinder. With much BF and BI I have finally got the overarm on the horizontal mill out of the way:



Now that I've got some oil on the dovetails I can move the overarm just by pushing rather than walloping it with a copper mallet. I've also had to make a new drawbar for the face mill; M16 instead of 5/8" BSW. I might even get around to trying out the vertical head for the mill I bought some years back on Ebay:



The main issue with the vertical head is how to lift it onto the machine. That's a 12" rule leaning on it. When I bought it I managed to lift it out of the car boot and into the workshop. No way I can lift it unaided now.    At least temporarily I can get my neighbour to give me a hand but longer term I need some sort of mechanical assistance.

At the moment, partly by design, I don't have any work lined up for a few months. So once I've got my gliding holiday and my mothers 90th birthday bash out of the way I should have plenty of time for the workshop. Of course there are other calls, like the garden and house, but I can control the urge to do those jobs. 

Andrew

[Jo]

I might even get around to trying out the vertical head for the mill I bought some years back on Ebay:



The main issue with the vertical head is how to lift it onto the machine. That's a 12" rule leaning on it. When I bought it I managed to lift it out of the car boot and into the workshop. No way I can lift it unaided now.    At least temporarily I can get my neighbour to give me a hand but longer term I need some sort of mechanical assistance.

For my Harrison Vertical head fitting I have a board that mounts through the spindle and allows the head to safely stand vertically for lining up to the front of the machine. Getting it off the floor originally needed a crane but once on the board it can be moved around on my roller skate. You could easily do similar with that Andrew 

Looking forward to seeing your progress at the end of the month 

Jo

[jadge]

If I had the head on a stand at the same height as the table I could probably lift/slide it across. That's what I do with the dividing head, although I think the vertical head is rather heavier. Question is, have I got room for a small table?

Oeeeer, I'd better stand outside the hall while you and Jason inspect the parts and wait to be called in for the verdict. 

Andrew

[Jo]

This is my high tec head stand for the Harrison. Skillfully painted silver to stop me thinking it is a suitable candidate for the log burner. The thread in the top is for a drawbar through the vertical head. 

I have an over head crane for swopping over the Theil head as it is above head height 

Oeeeer, I'd better stand outside the hall while you and Jason inspect the parts and wait to be called in for the verdict. 

This is your last chance to do this. I am sure Jason is going to be very disappointed he won't have so many opportunities to prove his engines are better than everyone else's and show how well they run If he is too critical of your stuff ask him if he is enjoying himself still having to work for a living 

I said work  what a horrible thought   

Jo

[jadge]

If I do make a table I'll probably weld it up from steel tube.

It's a shame it will be the last meeting, but there are some things I won't miss. I'd better clean up the rear wheel though as it's got some rust spots on it. That's due to it being wet, wet and more wet at Forncett this year when I was unloading and loading my exhibits.

Andrew

[jadge]

When I riveted the spokes on the third rear wheel recently, the riveting proved to be more difficult than before. For some reason I had problems getting the riveting fixture aligned and the rivets didn't seem to close as nicely. Turns out the reason was simple; the bench top on which the fkypress sits was broken. 

The bench top is two 18mm sheets of MDF glued and screwed together. The bottom layer was badly cracked, meaning that the flypress was leaning backwards. Hence the alignment problems. Some while back I was given a piece of steel plate (600mm x 500mm x 15mm) from a failed aircraft project. I thought it'd make a good base for the flypress, and hold the bench top together at the same time. Drilling on the Bridgeport meant somewhat of an overhang:



I drilled and countersunk a pattern of holes for M12 screws. I also chain drilled and bored a 90mm diameter hole to match the hole in the base of the flypress. Here's the plate in place on the end of the bench:



And with the flypress installed using M16 bolts:



The whole setup feels pretty solid, and rather better than it was originally. I plan to assemble and rivet the final rear wheel over the next few weeks, so time will tell how well the plate works. It's also the first time that I've acquired something that turned out to be useful after someone said "do you just want.............".

Andrew

[mike mott]

It's also the first time that I've acquired something that turned out to be useful after someone said "do you just want.............".

That does not happen very often for sure, most often they are just trying get rid of it.

Mike

[jadge]

That does not happen very often for sure, most often they are just trying get rid of it.

Definitely been caught like that. I normally end up giving the stuff back, recycling it, or in the worst case paying the council to take it away. 

Andrew