On Michael's Workbench - Air Loco

[Marty Johnston]

The pressures were rather amazing. In some case they went up to 1000 PSI on the main tank. Using multiple Mannesmann tubes charged to 2200 PSI was another method for harnessing high pressure air power. The Mannesmann tubes were much smaller in diameter and looked like modern welding bottles.
The application to moving coke cars does seem a bit strange - must have been a reason....

 

[simond]

not quite the pressures of the likes of Fury, but without the accompanying thermal stresses (notwithstanding the chilling effect of expansion as Marty notes).

Never seen an "interheater" before, but have first hand experience of a freezing demand valve, at some 30m depth in Dorothea quarry in North Wales about 35 years ago. The valve simply froze open, and in the couple of minutes it took me and my buddy to ascend, my tank had pretty much emptied itself. It was entertaining, exciting even, but would not have been much fun at all if we had not been in a pretty relaxed environment.

 

[michael mott]

Hi Marty and thank you for joining this great site. Thank you for answering the many questions that I could not. This is a really fascinating area of Locomotive design and development, And now I know that the small lever is definitely the throttle. I am wondering why there was a single notch and and guessing it was to lock the loco in the off position.

Michael

 

[michael mott]

A couple more pedestrian shots of progress, The square collets really help with dealing with working on square bar so much less fiddling than the 4 jaw chuck.
First the lever end of the connecting rod from the drivers end. I was reasonably happy with the small square headed bolt filed up from a 0x80 flat head machine screw, I think it might need to be filed down a little smaller though.




The rod is bent to accommodate the difference in distance from the centre of the lever and valve. I glued in a couple of spigots to hold the sanding piping which I can finalize now that the valve connecting rod is sorted.



I really must put a lick of paint onto that big motor. also when all the other bits get put back on it will hide it a little better.



Michael

 

[michael mott]

The bitter cold and dark days of winter have been brightened up in the model-shop with a bit more progress fiddling about reassembling the loco, had to make a few adjustments here and there, and replace a few bits that the workshop gremlins seemed to have nicked.






After the small piping is added a bit more painting and then some weathering will be in order. I can see the light at the end of this tunnel now.

Michael

 

[michael mott]

A nice bit of progress today, now all the small pipes are installed, just the hooks and a couple of side filler valves then she can become a shelf queen for a bit, while i sort some other stuff out.


I am particularly pleased with the 00x90 square headed locking bolt on the air valve lever hub, and the valves of course.

Michael

 

[Giles]

A quite extraordinary piece of work and workmanship! Wonderful!

 

[michael mott]

Just finishing up the big filler valves on each side of the loco thought I would tackle the big wire one first which is on the opposite side to this picture This valve has a cast handle that will be fretted out of some 25 to 30 thou. sheet


Had to make some new bending jigs and was able to solder it all together now to get on with the clean up the threads on the valve are .225" x 40 it took longer to change the change wheels that cut the threads.

first the jig drawing


The top part was able to be made by modifying one of the earlier jigs, but i needed a new one for the bottom.



fettling the two halves together the wood is a block of English Boxwood cut from a 3" diameter log that I purchased from a wood dealer in Croydon in 1972. Just in case anyone is interested in these things.


The third hand does come in handy for soldering odd shapes I machined the centre cross bars from a bit of brass bar and so the 1/16th shaft is integral to the cross which I fretted out with the 08 blade in the jewelers saw. The shaft slipped into the maple dowel allowed the handle to rotate for soldering the 20x6 thou posts in between the outer ribs. I left the spikes on until all the soldering was done which helped with the handling.



The first pass of the clean up a bit more to go but this is a more accurate rendition of the wire handles, it is 1/2 inch in diameter.



Michael

 

[Dog Star]

Excellent stuff Michael, each post is a tribute to your skills in assessing how to "model" the details and then producing the result. I like the "walk-through" approach to the story.

Thank you, Graham

 

[michael mott]

Thanks for you kind comments Graham.
The -27 and snow are getting a bit tiresome
shot of the garden railway

The valve on the other side is a broken casting and i thought it would be fun to model it that way. so after making a drawing I printed it on label stock and stuck it to a bit of 1/16th thick brass off cut. It was easier to hold by positioning it the way I did, although I do not like wasting brass.



I opted for the regular bench dog rather that the one with the lock screws as it was easier to manipulate given the complexity of the shape. I penciled in the section that I was going to fret out, I broke one of the 08 blades, but that was the first one and not a new blade.


some of the bottom edges were a little thinner but overall I was happy with the result.



After a bit of fettling with a #8 rat tail file to round off the edges I gave it a blast the a shot of paint.





Blasted the wire one as well I might do a bit more filing on the corners of it though.



Time for some food.

Michael

 

[simond]

The broken handle is brilliant. Pity the poor driver…. (Mind you, he probably broke it.)

 

[michael mott]

Almost there, The next to last major items are made.

After a quick drawing the hooks were cut from some .084 brass using a 03 blade.


A few bits machined up on the lathe, and then the springs wound out of a bit of .093 copper wire.



Soldering the hook to the shaft.



ready for blasting after the hooks get their final shaping.



blasting done



a lick of primer





Now for supper.

Michael

 

[michael mott]

Almost there, all the parts are now made, I take my hat off to the folk who make miniature pressure gauges.
to drill the .029 holes I used a pressure fit on the end of some 1/2 inch brass rod, eyballed the three holes.




The hex bolts are filed up on the end of a bit of free machining brass turned down to the .029 shank and .070" held in the pin vice and 3 strokes of a # 8 cut file per side. All glued together.

The plywood disk is 3/64 birch aircraft ply.



let every thing sit for a few days then some weathering.

Michael

 

[Lyndhurstman]

A truly wonderful thread. Exquisite modelling, and a considerate approach to Show & Tell. Inspirational, for me. Thank you.

Cheers

Jan

 

[Rob Pulham]

Jan has put it far more eloquently than I was able to come up with. a superb bit of modelling.

I do wish that I had some where near your stock of materials too.

 

[michael mott]

I do wish that I had some where near your stock of materials too.

Thanks for all the likes and kind comments, Rob, My stock of materials is because I am basically a pack rat and save all my offcuts and have been doing that for nigh on 50 years. When I worked doing commercial modelmaking I purchased industrial type packages from evergreen for architectural details back in 1980, The supply is getting a bit yellow now at open end so I keep the stash in the dark in a cupboard to avoid UV. Having a branch of Metal supermarket a few blocks away can be a problem as well. I once salvaged a Venetian blind from the dump (transfer station that had a take it or leave it area) The blind had been chewed in one corner by a dog. The wood is basswood or lime and stable and flat in 1/8th x 2 inch strips great for re-sawing for various modelwork. like these window frames on my old layout called Macton locomotive works


By cutting the notch (rebate first with a hollow ground no set plywood blade flipping it end for end to maintain the distances keeping the bulk of the material between the fence and the blade. next the rebated edges were sliced off for the window frames, scale 1/24th the mictoscope glass was puttied in with a model filler.
Some of the filler was left off to represent old fallen out areas.



The stone was strips of MDF. in this version of the "Drawing Office" The rebuild was card below.





Corrugated Iron was brass .003 shimstock run through a Fiskars paper crimper. Gare was brass and copper the letters "Forged" from beaten copper wire.

Well I did not expect to go down that rabbit hole!

Michael

 

[King Crab]

I like the special jigs and tools all of which go together to produce a fabulous model!

Peter

 

[Marty Johnston]

Hi Mike,
The loco is looking fabulous! I really like the broken handle.
Marty

 

[Scale7JB]

Magnificent, Michael..

Not sure how I missed all this..

JB.

 

[michael mott]

Hi Marty thanks, JB glad you found it.
I nervously put the battery and Locoremote back inside and gave it a test.

Vimeo



I wanted to see it in Black and white.

Michael