On Michael's Workbench - Air Loco

[michael mott]

The Air Loco that I am currently working on began life as an 0-4-0 Aristocraft 1:29 Loco The first modification that I did was in 2002 and looked like this. My original build was based on the mine loco at the Canmore Museum



It had smaller tank with round rivets.




By 2003 it had changed a little more.


The model sat for a while then was worked on some more in 2006



A better looking set of cylinders was the goal.


By 2007 the original frame had been modified some more thinning out the framing this was a result of wanting to make the loco resemble the one at Bankhead a bit closer.



large change occurred in 2009 with a new longer tank like the tank on the Bankhead loco.

T

This tank had a lot more rivets and a different shape. The front of the tank had a slightly oval opening for the clean out hatch, which was solved by distorting the center part with some plastic wedges and then filling.



The loco sat like this for some time as other projects came and went.

At least this post give the beginning backstory to the present saga.

Michael

 

[michael mott]

Jumping ahead to 2021 I opened the tin with some of the air loco parts and began remembering what it was that I liked about this loco. I had reworked one of the cylinders and had all the parts for the second on, so began the recent rework.



here are a few pictures and the latest work on the frames which were done in brass to replace the styrene ones that were sagging.

The end buffer beams were a bit oversized so the are being remade as well. The final look will be similar.

But I am happy that the frames are now straight.
The loco is meant to represent this one that is on display at Banff as part of the Bankhead Mine display

A look at the front end and the inspection hatch. Since I took this phot the front buffer beam has been all but destroyed with the hook now missing and very little left of the wood.

Eventually I will make a decent model from scratch with an all brass construction with the proper gauge which was 27 inches, this model was built to a scale of 30mm to the foot so that the 45mm gauge track represented 18 inches.

The present model will get finished here the new frames are receiving the plastic cylinders. using a self made 1/8th socket wrench.

Hopefully the rest of the posts relating to this loco can be moved over to this thread from the whats on your workbench 2021 .

Michael

 

[michael mott]

While waiting for a couple of C5 collets to hold 3/32 and 1/8th square stock I jury rigged the lathe to hold the 3/32 in the small 4 jaw chuck. because I needed to make some 0x80 nuts and bolts for the front of the footplate.



The footplate was cut from some .010" brass then annealed and beaten up with various blunt implements to simulat a bit of wear and things being dropped on it. after that the holes were drilled then the sheet was washed in acetone and given a bath of Flemish Grey black Jax chemical. The small section side angles will get "welded" to the edges with some heavy application of soft solder. bolts need to get treated as well.



The fitting of the front buffer beam has commenced as well.



I think I need to give the tank a lick of colour to unify its appearance a bit.

Michael

 

[Tom Insole]

Lovely to see a thread for your fine craftsmanship Michael. I always love seeing the updates in the "what's on your workbench" thread so I've quickly clicked the follow thread button on this one! Keep those updates coming. Rather looking forward to seeing the final result.

 

[michael mott]

Well the lick of paint had to wait till I added the 4 rows of rivets that I missed, so had to make a bunch more today, fortunately I still had a length of 3/16 cell-cast acrylic rod (so much easier to turn and work with than the extruded type)
I could not remember the exact sequence for the first batch, so modified a cutting tool to get close so that I could turn the curve then index it over and part off the rivet. The parting tool left a little spigot which got snipped of with some flush cutters then placed flat side down on a 220 sanding stick and the open end of a pin vice was just the right size to act as a pressure holding device to sand the back clean. sorry about the dodgy pic


The extra rivets were then attached with some plastruct multi plastic solvent. I also drilled all the rest of the relevant holes for pipes and brackets etc and decided to cut a square opening on the same side as the brake quadrant that will be hidden under the sand box that is bolted to the tank, the hole is big enough to slide a 4 pack of AA batteries through or a loco remote module.

Then I gave it a coat of Vallejo red brown primer, which will serve as the undercoat for all the rust treatments to follow.



Did the cylinders at the same time.



Michael

 

[michael mott]

The original Aristo wheels were bothering me with the larger than life flanges.



I pulled then out of the plastic worm gear (will have to re quarter them) and skimmed off a chuck in the lathe, The decided to add the extra counterbalance on the mine loco wheels.




with a bit of styrene once the thick ACC has fully cured I will fill up the gap with some spot putty.



Late yesterday I gave the frame and tank a mist of a darker rust and by adjusting the airbrush was able to add a slight texture.
Then this morning after the obligatory 12 hours I dusted it all again with a slightly chalky rust colour. It is beginning to look closer the the right base colour.

Especially the frame, The tank will get more texture yet. Them one the colour is right I will begin adding the accumulated dust and grime.



Lots of work to do yet, But it does feel good to finally begin to get some unity to the overall assembly.

Michael

 

[simond]

This is really rather splendid.

 

[michael mott]

I cannot remember where I read that if you blacken brass then it could be painted with various primers. Previously I had primed the brass with Zinc Chromate primer first. Well be that as it may, I would have been wise to continue my previous practice. After a good stripping in some clean Lacquer thinner I repainted the frames with some Zinc Chromate primer.

Then I can start over with the rust colour when it is cured.

For the rest of the wheel counterbalance filler pieces instead of a lot of filing and fiddling, A bit of geometry and the #05 jewelers blade.


It turned out that the geometry was a bit off so re cut them from the same sheet of .030 Styrene with a #08 blade then glued filled and sanded.



And then gave them a couple of coats of the Zinc Chromate.


Also earlier had flipped the tank to catch the opposite end lip and catch the areas that were a tad thin around some of the rivets. One step forwards and a couple back seems to be a common thread for me.

Michael

 

[michael mott]

While the rear dome was off to paint the cylindrical part of the tank I took the opportunity to work on the brackets that had bee constantly put off because I was ruminating about how to go about making them and because they had not been drawn yet. The rear dome is full of interesting parts and a little complex because of the hemispherical dome.

After getting some preliminary drawing done to act as reference guides I clamped the dome into my trusty grinding vice that I made as an apprentice many moons ago. it is square to itself on the bottom, sides and end within 2 tenths of a thou and was lapped to a mirror finish 57 years ago. I took the scribing blade out of the dial height gauge and slotted in a piece of the compass drawing instrument with a 4h lead.

This allowed me to transfer the lines from the drawing without having to worry about the geometry of the dome. them flipped it onto its side to do the other datum's


It occurred to me that a light grey primer would have been much more useful at this stage.


Next task was to drill the holes for the various fittings and the bracket bolts, The angled vice comes in handy for this sort of job. As I did not have the knowledge base to calculate all the settings for drilling the holes perpendicular in the freehand turned dome, It was all down to eyeballing the drill being at right angles to the spot being drilled.


It took a while to get these different holes lined up, for drilling and tapping.



It is slow but I like to tap the hole right away after drilling because everything is lined up, The tap is momentarily held in the chuck then released just enough to let the tap fall into the hole, and the finger wheel lets me get the tap to do its work.


These first two plates fit well enough but were a tad too narrow so had to make a couple of extras.
the problem was that as I tightened up the hex bolts the bracket gave way and became un-soldered The one in the picture has be re-soldered to the slightly wider one. The bolts are home made 1x72 turned up from some 1/8th diameter brass rod then filed up in the 1x72 filing hex button.

The soldering was accomplished using my third hand which is nice because I can set up items very precisely and check it over by rotating it to chek that the surfaces are mating well.



The large flange that is riveted for the air to the cylinders was turned up in two main parts on the lathe from bit of 3/4 inch bar and some 3/8 inch bar. there are 8 rivets and I opted to glue this all together on the dome rather than attempting to solder it all together ( I was chicken thinking about getting the angles of the two main parts correct). Once the outer diameter and the bore of the flange were turned I transferred the chuck without removing the bar to the mill to drill the eight rivet holes for the brass rivets which were smaller versions of the main tank ones.


My poor mans rotary table, this is quick and simple and avoids all sort of time to set up the 10 inch rotary one that weighs in at about 100lbs.


The 2 bracket were close enough that A couple of twizzles of the tapered clock reamer each way and the .093 brass rod slipped through nicely.


Drawing continues now on the valves and the other bits.




It snowed today so winter has finally arrived, guess I won't be doing much outside in the garden now till late march.

Michael

 

[simond]

Michael,

Im much enjoying your thread, and particularly liked your comment about drilling and tapping at one setting. I will make myself a couple of those finger grip rings to suit my main taps. Thanks

Simon

 

[michael mott]

Simon thanks, you will find that they are really useful. Originally I made them round but found that because of my fingers sliding, that changing the shape to one with flats made life much better. I used a 4x40 grub screw to hold the tap which helps to keep the perimeter clean. slippage has not been a problem. I also use the same method when tapping something in the lathe. I would recommend having a couple of the same size so that you can switch between start or second and bottom or you will spend a lot of time changing them out from one tap to the other as you work.

Michael

 

[michael mott]

The valve in front of the safety valve is a complex little bit for sure. After the initial turning and boring of the .086" hole through the center the main part of the body was parted off and then cross drilled for the main pipe with a .180 drill(#15) then the main .076" holes for the horizontal clamp bars, then the pair of .076" holes for the bottom clamp bars on the mill.
Then back to the lathe and glued onto a .179" spigot as shown in this picture to turn the side ends of the body.



After turning a soak in some acetone to un-glue it , the opposite end was turned. Next it was set up back in the original orientation to reduce some more of the main body material. this time on a .086" spigot, on the end of a bit of 3/16th rod. This rod was also used to hold the part for all the hand filing.



Being able to hold the body this way made all the repositioning a lot easier.



Then with an assortment of needle files the rest of the shaping took a while. The top hex section was turned from some 3/16th hex material. and the bottom round ring type nuts were made from some 5/16th bar stock and the notches hand filed in the hex pin vice.





The bottom thread is 1x72 UNF
Next will be the handle, I suspect that the additional plate bolted across the top was to facilitate a wrench to snug up the valve. then the clamping plates for the sides and the bottom.

Michael

 

[michael mott]

At first I took a piece of 1/4 inch hex stock and turned down some sections, the idea was to anneal it then bend it into a right angle elbow. Then remembered that I had made a bunch of various elbows for another project a couple of years ago so had a rummage in the pipe fittings spares bin.


Pulled out a couple of tight 3/16th elbows but these were not quite suitable enough so decided that a new approach and that what was needed was a bit of pipe that was long enough to hold all the parts with a tight elbow at the tank end.

So using my kit of miniature pipe making and fittings tools I bent up a new elbow with a long end.




By using the large and small diameter bending tubes i was able to get a nice tight elbow.


The 1/4 inch hex was drilled and parted off to create the ends of the elbow.
Next the clamp flanges were turned to thickness the drilled together and parted off the first pair were a wider distance than the third so they were drilled and parted off. Then back to the mill to drill the last one for the bottom.



Then the clamp bars were threaded and nuts made

The disk clamp plates were shaped with the jewelers saw with a #05 blade and cleaned up with some emery boards and files.





Tomorrow the handle and pressure valve.

Michael

 

[michael mott]

The first pressure valve ended in a lot of bad words, as it was snatched by a drill.

A decision to use a new approach with reverence to the "Dinsdale Brothers" was the turning point. The long bolt is just a keeper for soldering, Also a choice to just soft solder this time. The coil spring was hacked off a tension spring in the spare springs drawer.



A soldering session


After a bit of cleaning up a dry assembly



It was at this point that the Dinsdale brothers saw that the operation was flawed!



And so embarked on the final plan, which entailed making a new keeper bolt in order to rotate the top spring retainer to clear the valve handle.







It didn't seem like it took 7 days to make this little set up but it did.





A bit more soldering before moving along is in order.

Michael

 

[Tom Insole]

That's absolutely stunning. I can really appreciate the engineering that went into making the assembly. Bravo!

 

[michael mott]

Thanks Tom
After an attempt to paint some of the parts and then assemble the set I ended up stripping the paint off, and have chosen to use the Jax patina colours of bronze black and Finnish Black then reassembled and put a little ACC glue on a couple of spots twice as it turned out because I glued the valve on upside down....(don't ask it was one of those mornings) so after that was all done, I tackled the valve lever. The round portion was soft soldered to the rectangular section

The pawl was milled out of a bit of 1/8th square bare and some filing.



The notches cut with the jewelers saw. The raised portion fitting into the .062 x .303 slot in the long part of the lever.





I will be using a combination of lacquer paint and rust powders on the clamps and bars of the valve assembly when the dome has all the parts finished being fabricated. I like the acrylics on plastic not really happy with them on the brass. There is an interesting article in the latest Narrow Gauge and Industrial Railway Modelling Review. by Tim Shackleton, on weathering, where he talks about how many shades of black are there on a weathered steam locomotive. For me it is how many levels and textures of rust are there. I will see what I can do with some fine brushes.

Michael

 

[michael mott]

I ended up making a second pawl that engaged in both slots, By moving the extension toward the tank. Made the hubs for the shaft and all the rest of the bits for the handle, then popped the dome into the tank just to see how it looks.
Used a #08 blade on the .016" material, it was easier ti bend the material first then drill the holes and finally fret out the handle.



The hub for the handle will get soldered to it. I am unable to decipher how the shaft is able to lock to the handle even by looking at 3 different pictures of it, so decided to use a taper pin. the other spacing collar inside the opposite bracket is threaded for a 00x90 bolt. I also thinned down a couple of 00x90 nuts to act as jam nuts that lock on the lever to the shaft. and filed one of the 00x90 bolts to a square configuration, on the bolt through the pawl.







Michael

 

[michael mott]

So now I take my hat off to you folk who build all those incredible backheads on 4mm and 7mm locos especially the large mainline ones with a whole swack of pipes and valves an sight glasses etc.
Making and bending up these two bits of pipe and fitting them to the back of the tank and the valve took a big part of the day. end on the right is for the pressure gauge.







The fittings connecting to the tank were spun up out of some 1/8th hex stock.

Michael

 

[Tom Insole]

This loco is getting harder and harder to notice it's a model! Bravo. I've got to do something similar at some point when I start putting time in on my Edward Thomas scratch build! it's one of the bits I also dread, after seeing your work I may have to come ask advice when I come to it

 

[michael mott]

It is a good job that I am still sane.... well I believe I am others might question that. The challenge that these little valve handles have been.


I have no idea how many hours now that I have been mucking about with jigs full of pins of different diameters and numbers, mostly 16 pins of 2 sizes.

I did try a set with 6 facets, but it really wants 8. My final design (for the moment) is using the small 8 lobed flower.

The first jig was a bit large but was more of a proof of concept, and I had trouble soldering the inner lobes together because I was using the wrong methodology.



I did a number of experiments with small ovals and flattened then in a useful little gizmo I was given by the son of a watchmaker. a simple clever anvil





5 taps with the small hammer and A number of little flat ovals ( I'm sure they will come in handy for something.
An obligatory glam shot of various jigs and the end products. I even tried annealing a spring and bending it into a circle.



The 6 lobed one did not look right after bending up. and was a bit too small anyway.



I occurred to me at some point this morning that I needed to solder all the inner lobes at the same time and add the hub as well. As Dinsdale would say this was the turning point.



After a couple more practice runs this are looking better. The center pin is 1/8th in diameter with an .054 shaft.



After a little coaxing it is feeling like I can live with it. The little 6 lobed one on the left is just too small, for this application.



Popped into the end of a sort of valve body to get a feel for the proportions.



I'm going to give my tired eyes a rest.

Michael