We were on our way back from Bedale on Monday morning when we realised that we were following one of the last few runs of the Black 5 which has been heading up the Polar Express.
When heading the Polar Express the loco is in steam but not really doing much work as it’s actually being pulled one way and pushed the other way by the Class 47 on the other end of the train. We live on a slight rise so we would hear the chatter if the loco was doing any ‘work’, this has been absent on the Polar Express for the last few years.
However on two of the running days between Christmas and the New Year the steam loco actually does the work of pulling the train.
Getting back to Monday, Chris joked about racing the train and we soon caught up to it just before Crakehall crossing. From there we moved ahead and I was able to pull up in a farm lane just to the east of the village where we could see the train coming from a long way off so I decided to try an video it.
Apologies about the slight glitch in the middle where I got out of the car to get a better shot as it came closer. – What a lovely sound!
In between the festivities I have been making further progress on the 8F chassis and motion. Way back I had bought a full set of motion from Premier in ignorance at the time that sometimes for whatever reason the kit centres don’t always match those of the Premiers rods. In this case the coupling and connecting rods are fine but most of the others aren’t. I had previously spent some time fitting forks to the radius rods but I hadn’t assembled enough of the motion to check that they would actually fit.
Premier Radius Rods – too long for the MOK 8F
Spoiler alert, they don’t.
Which was a bit of a shame because I had also fitted a sliding block for the reversing links. Hey ho, I still had the kit rods so I made those up.
I had in the past, determined that the Combination levers for my engine should be fluted, whereas the Premier rods are plain. So, they too are in the spares box, as are the Union links because I couldn’t see how I might make them forked.
Returning to the coupling rods, after shortening all the bushes I decided that I couldn’t live with the brass bushed for the two front axles because they ultimately become the ‘crankpin nuts due to lack of clearance on the prototype. So using the nothing looks like steel than steel maxim I made some replacements from steel and I also made up some of the large flanged nuts that retain the rear of the coupling rods.
After this image was taken I did thin down the flanges somewhat.
Next up was recessing the coupling rods at the first pair of holes.
I machined up a stub of bar that was a close fit in the coupling rod holes and fastened them to my Metalsmith drilling plate. Using the stub of ba as a locating pin I was able to adjust the mill tables until it dropped smoothly into the hole and then swap the stub out for a 4mm slot drill which I used to recess the our hole for the flange of the bush.
Recessing Coupling RodsRecessing Coupling Rods
You will note the black marker spot on the side of the rod. This was to ensure that I didn’t inadvertently recess the wrong end…
Here we are to date with the bits that are fitted so far working without catching or unscrewing them selves when the loco runs in reverse. The next job is the return cranks when I will determine if the Premier Eccentric rod, fits or not.
One of the many things that I love about having a lathe, is the fact that it makes it so much easier to get a consistent result while tackling some of the more tedious tasks in railway modelling. A task that I have aways found tedious*, is cutting/filing crank pin bushes to length so that they allow some play in the coupling rod and don’t bind or unscrew themselves when running in reverse.
*Mainly because although I can follow a line with a saw without too much difficulty, I really struggle to file surfaces at 90 degrees to the edge. To get around this on the 8F, I turned up a little Arbor from some mild steel bar (more recycled toner cartridge rod). I threaded the end 10ba and using a 10ba nut, I was able to fit the tapped bush on the end then lock it with the nut and quickly and consistently remove 0.9mm from each one.
I have spent the last week or so fixing a number of mistakes that I made back when I didn’t know any better. For example, I realised when trying to fit the wheels that I had assembled the Premier coupling rods as a pair rather than handed, so one side only fit inside out. At the back of the workbench, I found an old pin punch. I popped it in the lathe and turned a small spigot on the end, to allow me to carefully pop out the rivets and swap the sections of rod around.
Once corrected I was happy to find that the rods ran smoothly in both directions without any sign of binding.
(As an aside I do like the built in motor restraint which is a nice bit of design work.)
The next bit of corrective action took most of a day to sort out. I had previously bent and fitted the two steam pipe sections that fit between the grease separator and the exhaust steam injector. These are made from 3.1mm copper rod which takes a bit of working to shape. Fast forward a few years and the grease separator casting had come adrift from its mounting pad and I hadn’t actually secured the front section of pipe. It was just pressed into the front flange of the grease separator casting. Without paying much attention I soldered the grease separator casting back in place and moved on to more of the motion parts.
While working on these I thought that it might be wise to fit the wheels and check that the Premier coupling rods matched the MOK wheel base and that I had a smooth-running chassis. It was at this point that I realised that the route of the steam pipe prevented the rear axle from moving through its full travel once the motor was fitted – The rear axle sat a good millimetre higher than the front axles. So, I removed the pipe (and the castings at either end) adjusted them and refitted to find that the pipe now hit the tyre on the rear wheel.
At this point I stopped refitting the castings and just kept adjusting the pipe bends. I did much of this with the aid of my vice, a thick-walled steel tube filled with lead and a white rubber mallet. I also made use of the “Markits” BA nut spinner set for making the tight tweaks to the very end bends after finding that the 8BA size just fit over the copper rod. I spent a couple of hours on Christmas Eve and around six hours yesterday before I finally got it to fit in place and clear both rear wheel and allow full vertical movement of the gearbox.
In reality once I come to set the ride height, the vertical movement of the gearbox may be less of an issue but better safe than sorry.
You will of course note that this isn’t the same crane. It’s a second mobile (wagon mounted) version of the crane. I also managed to get a few decent renders
After these were taken I adjusted the angle of the job stay connectors
Then I realised that although I had fitted the inner geared roller which is for the brake I hadn’t done anything about the brake handle itself. So back to the drawing board…
Wow, it’s been a while since I last updated this topic. I confess that I have done very little 3D drawing since March mainly things that I intended to machine and modelled them to make working drawings.
I have done so little that when a friend whom I had drawn a number of items in the past asked me to draw up a GNR axle box and horn guide I had no idea how to go about it. Fast forward to a week ago and I decided that after drawing up the side control spring for the 8F that I needed more practice and to relearn how to draw in Fusion beyond the basics. Having recently messed about with gears and I had recreated some gears for my Medley Models Cravens Crane, I decided that I would attempt to draw up a hand crane similar to the one that I built some years ago from a Wagon and Carriage Works kit.
I wanted to go a step further than I have previously where I have built up a design as one entity and create components which would eventually create an assembly.
The W&C kit is designed to make either a wagon mounted mobile crane or a ground/plinth mounted yard crane. I have drawn up parts for both and started to assemble the Yard crane variant first as being the slightly simpler of the two.
It’s been a bit of a learning curve but an enjoyable one.
It was kindly pointed out that there is in fact a second spring that sits in the same place behind the pony truck but it isn’t shown fully on the plan view of the GA. If you look very closely at the plan view you can see just a small section of it that has been cut away to show other detail. But once you know what you are looking at, you can see it clearly on the side view.
Like most things making a second one was easier than the first because I revised the order of operations and I didn’t part it off from the main stock until after I had wound the ‘spring’ wire around it giving me a hand to hold whilst winding.
I also turned all the centre section down to the largest diameter which is that of the plates at either end of the spring, then I used a hexagonal collet block to mill the two nuts using a 2mm end mill and then finally turning the other sections to final size then using a round file to shape the curved sections at each end.
2nd side control spring in progress
Once the cosmetic spring was added it looked like this. It only needed the finest touch with a file to remove the parting nub to make it fit between the frames.
2nd side control spring
For a mad moment I did consider remaking the first one but then sanity prevailed and I decided to put the first one to the back where it won’t be seen at all and put the second better (in my view) one at the front where not much of it will be seen either.
8F Pony Trick Side control springs8F Pony Trick Side control springs
Some time ago I started to scratch build a number of Open Carriage Trucks. There are three GNR examples one GER example all of which are four wheeled but there is also a six wheeled NER OCT. These were large complete but lack final details such as brakes.
For a number of weeks at our weekly arts and crafts group, I have been slowly making a large packing case to fit on the NER OCT. This is made from coffee stirrers and the plan is to represent the OCT as it was modified during WWI when the drop sides were removed and four bolsters added so that the wagons could be used for transporting aeroplane parts.
Packing CasePacking casePacking Case on Converted NER OCT
I still need to complete the OCT itself and add a few more details to the packing case but it’s getting there.
Although progress has been slow since my last post, I haven’t been entirely idle. First, I fitted the brake cylinder that Adrian made for me some time ago for which I am very grateful.
Replacement Brake Cylinder
Then for some reason which I can’t recall I was looking at the GA of the pony truck in the Wild Swan book and realised that detailed as the MOK Pony Truck is it’s missing the side control spring.
I scanned the GA, imported it into Fusion and having scaled it, I then drew up the spring and it’s mounting.
From there it was easy to create a dimensioned drawing to allow me to attempt to make one.
I debated whether to make it in one piece and then wind wire around it to represent the spring or to make it in two pieces and thread the centre section 4ba (3.6mm) which is the nearest sized die that I have to the 3.5mm that I had worked out from the drawing. I decided to have a go at making the one-piece version first. If that didn’t look good enough, I would have another go.
8F Side Control Spring
There was a slight discrepancy between the GA and the actual width of my pony truck so I ended up turning a couple of thin spacers to fill the gap but it worked out okay in the end.
8F Side Control Spring fitted8F Side Control Spring fitted8F Side Control Spring fitted
As you can see, it actually sits largely out of sight (when viewed from the front) but I enjoyed making it, and I know it’s there.
Now that I have largely scratched my gear cutting itch, I returned to the 8F in the last couple of days. Starting with revisiting the chassis.
First, I resoldered a couple of bits of the cylinder wrappers where they had sprung over time due to being under tension. Then, I noted that in the dim and distant (2013) when I first built the cylinders and fitted the slide bars and cross heads, I had fitted piston rods from 2mm brass bar.
I cannot recall whether they came separately or whether the cast piston rod was so out of shape that I cut them off and drilled them out to accept a piece of rod. In any event not knowing any better I had used brass rather than nickel of anything that remotely looked steel like. As soon as I picked them up, I decided that they had to go. So initially I planned to use some nickel rod.
Unfortunately, my 2mm nickel rod is in fact 1.86mm so was very sloppy fit in all the holes. I also had 2.25mm and I did attempt to turn it down but ended up with multiple fine steps which wouldn’t fit either. However, what I do have is some 2mm ground silver steel so I cut a couple of pieces and used that. I used Bakers Fluid as flux and soldered them in. Although a reasonable fit in the holes in the cross heads I found that getting the piston rod ‘square’ in all planes was a bit if a trial. Made slightly more awkward by the fact that the drop links are a separate item soldered on so I had to be careful that I didn’t have them fall off as I soldered the piston rods in.
After initially soldering the piston rods in and finding that they didn’t runs smoothly due to being slightly out in one plane or another I hit upon the ide of fitting the cross heads into the slide bars then I gripped the drop link in a pair of pliers so that it didn’t move and then I slipped a pair of self-locking tweezers over the slide bars where the cross head was (with the piston rod fed into the gland at the other end). I then used the Microflame to heat the crosshead/piston rod joint, until the solder started to melt.
Then, as the solder melted again there was a satisfying click, the self-locking tweezers pulled the cross head into line with the slide bars and with the piston rod being held in line in the gland, it made everything line up in all planes. When cooled, the cross head/piston rod runs very smoothly indeed. A quick rinse and repeat for the other side had both crossheads running nicely. I think that when I assemble the rest of the motion, I may need to shorten the piston rods a little but I will wait until later in the build to determine that for certain.
Over on Western Thunder a fellow member posted photos of a hand crank that he had made for his lathe and I said that it might make a good side project at some point.
Talking of side projects. I have mentioned a few times that I am using a Spin Indexer to index the gear blanks for cutting.
Most comercial Spin Indexers are made in China and having seen quite a number of videos on the use of, and improvement of them one thing that pretty much everyone comments on is the locking screw which locks the barrel both while indexing and fitting and tightening items in the collet holder. As supplied they come with and aluminum screw which has a nice knurled head but that’s the only good thing that you can say about it.
The fit in the internal thread is so sloppy that I wouldn’t be surprised if there wasn’t getting on for a millimetre of play in the thread. Now most of the videos that I have watched have been Americans and the other thing that they found really frustrating was that they couldn’t work out what thread it was. That’s because it’s an metric M12 x 1.75 thread.
I do have a tap and die for M12 x 1.75 but by good fortune I was recently given a bag of big bolts to use as raw materials and amongst them was a number of M12 coach bolts. I tried screwing one of them into the hole of the Spin indexer and the fit was perfect.
I cut of the head of the coach bolt and then cut a length of the threaded section and included short length of the plain shank, which I turned down to make it round as it was slightly oval to start with. Then I drilled all the way through 5mm because the aluminium version has a hole through it. I opened out the threaded end to 8mm and turned a brass top hat bush to fit inside it and secured it with Loctite.
Next I used a boring bar to open out the hole in the knurled part of the aluminium screw until it fitted the turned down section of the replacement threaded section. Then I parted it off and Loctited that to recreate the screw.
Now I have a screw that will tighten down properly with no slop in the threads and the brass end will stop the barrel of the Spin Indexer from getting chewed up by the steel screw thread.
After playing about with several iterations of differing angles to help the spur gear mesh with the newly created worms I realised that I had been angling the spin indexer in the wrong direction. I quickly placed my piece of 3mm rod under the other end of the Spin Indexer so that the nose angled down not up and then cut another gear.
Hey presto, we have a working worm and spur gear.
I also took a little video of it running in my friend’s G5 chassis.
It is a little noisy but I attribute much of that down to the etched gear frame. To confirm this diagnosis, I test fitted a proprietary gear set from Roxey Mouldings that I have in stock and that was just as noisy.
This week has been very much about more learning. First of all, although I reground the 20 degrees cutting tool, I had still left too much of an undercut and the point snapped off again after about five passes.
I did manage to make another worm, the best to date but it was still cut with a standard 60 degrees thread tool – more for the practice at single point threading than an expectation of it actually being used as a worm at some point.
I also made an arbour to hold my gear blanks. I made this primarily because the largest brass bar that I have which is 19mm diameter and is just the right size for a 36-tooth Mod 0.5 gear. I only had approx. 200mm/8 inches, so I wanted as little waste as I could get away with to make best use of it.
The arbor has a short section at 3/16 and then the end is threaded M4 for a locking nut.
With it made I then cut a 36-tooth gear.
Mod 0.5 Gear
After some off line discussion with a fellow member of Western Thunder and much grinding of my cutting tool, I finally managed to get a 20 degrees tool with sufficient support underneath the point and was able to cut a ‘proper’ worm to suit my mod 0.5 gear. On Susie’s advice I wound the lathe over by hand rather than under power to cut the worm. Now I don’t have any kind of ‘handle’ to allow me to turn the lathe over smoothly (I have seen other machinists who make an expanding arbor for their lathe spindle to allow smooth hand cranking) so my effort using the holes in the collet chuck and a tommy bar were quite laborious but I got it done.
I also had another go at making a gear but with a slight angle to the teeth to better mesh with the worm.
My method of creating an angle on the teeth is very unscientific, I started off by adding a length of 0.7mm nickel rod under the front end of the spin indexer to raise it up and it did work albeit not enough and I also forgot to raise the cutter height so I ended up with slightly lopsided teeth and the angle wasn’t quite enough.
Undeterred, I increased the rod size to 1mm and tried again. It was at this point that my learning experience went into overdrive. According to the charts that I have been using* the cutting depth for Mod 0.5 is 1mm thinking I was being clever I increased that by 0.1mm. As soon as I made the first pass, I realised that something was wrong. The cutter had not only cut the tooth but it had also created a much wider channel in the blank which you can see on the right-hand side of my hacked about blank below.
Cutting Depth Experiments
The rest of the teeth on the damaged blank were created by my testing of various cutting depths to determine the point where the cutter cut the tooth without removing any from what would become the adjacent tooth and thus reducing the overall diameter of the gear. After a few test cuts, I determined that for my cutters 0.8mm was the maximum depth before it effectively reduced the height of the adjacent tooth.
*Bob did point out earlier in the discussion that the charts were actually for the cutting of worms rather than gears but we determined that in the absence of any other data that they were near enough for both.
For the Mod 0.3 the data from the chart worked fine and now that I know I can refine my own version based on what I have determined. No doubt that if I do buy a set of Mod 0.4 cutters in the future, I will have to do some tests to refine the Mod 0.4 data to suit the practical application with my set up.
Once I had made that discovery, I cut another gear and although it was successful, it still wasn’t angled enough so I will do further experiments on my duff blank to see how a 1.6mm lift works, before committing to another full gear cut.
Finally, to round off this war and peace update I also cut another worm with the 20 degrees tool in a piece of free cutting mild steel (the others were cut in recycled printer bars) under power and I think that it’s a much nicer worm albeit that there isn’t much visible difference from the ‘hand powered’ example.
Although not strictly speaking specifically gear cutting per, se I had another ‘first’ yesterday. This ‘first’ was single point thread cutting which I have never attempted before. For those that don’t know what single point thread cutting is, it’s the cutting of a thread using a cutting tool in the lathe rather than a traditional threading die (which I used to cut the 0BA worm a few days ago).
The pitch of the thread is determined either by altering gearing via several levers (if your lathe is so equipped) or in the case of many smaller hobby lathes it’s achieved by the use of change gears. Mine is the latter. What the change gears do is alter the rotation of the lead screw so that when the automatic feed is engaged, it moves the carriage a certain distance for each revolution. In my case I needed a 1.5mm pitch so I needed to swap out my standard gear set up for a 30 tooth (A), a 50 tooth(B), a 55 tooth(C), and a 35 tooth(D)
This was the standard gear layout
Original Change Gear Placemnt
This is the gear layout for a 1.5mm pitch
Once I had them setup, I put some layout fluid on a piece of nickel bar and did a scratch pass to make sure that I hadn’t made any mistakes.
scratch pass
Then I had a go at cutting a thread using a proprietary standard* 60 degrees thread cutting tool.
*Threads come in many different flavours depending on whether you are using metric, imperial, BA or many of the other thread types. Below is a thread tool gauge designed to assist when grinding your own cutting tools. As you can see US Imperial and Metric use the same standard which is 60 degrees.
Moore and Wright Thread Tool Gauge
I used this mainly because I had never done it before and I wanted to use a known good set up rather than a tool I had ground myself (which proved a wise choice).
I am happy to report that all went as planned, although I did over shoot the thread gutter a couple times because I hadn’t really made it wide enough to allow the machine to stop at this pitch and I successfully cut a screw thread.
Another good session in the workshop. On the back of this I had another go later in the day, using a piece of steel and the cutter that I had ground. Sadly, as I half suspected, the tip broke off the cutter after about 5 passes. This was due I think, to being ground on a taper, which meant there was nothing under the point to offer any support. Plus being carbide, it was quite brittle.
This actually turned out to be a blessing in disguise as when I started to grind a proper piece of tool steel, I realised that my 20 degrees angle, actually gave me 40 degrees included angle. A mistake that I had also made on the first one.
Thankfully it was a case of taking more off rather than starting again so I just need to finish off grinding it to shape after posting this.
The last two days have been a bit of a milestone in my gear cutting journey as I have managed to cut the missing gears for my two Shogun gearboxes.
Shop Made MOD 0.3 Final Drive Gear
I initially test fitted them and ran the motors with the gear rotating on the axle as I didn’t have any small enough grub screws and was pleasantly surprised when they ran freely. Next, I made some tiny grub screws from some lengths of 10ba stud that I had cut off some one inch, 10ba screws. I keep all such things in a plastic Ferrero Roche box as they do come in from time to time. I was trying to be a bit clever by using a very small slitting saw in the Proxxon pillar drill to cut the slot but the blades that I have, are too thick and it ate away half the thickness of the screw. So I cut the slots by hand with a piercing saw.
Shopmade Final Drive Gears Fitted to Shogun Gearboxes
After chasing them around the workshop floor and miraculously finding them after dropping one grub twice and the other once, I fitted the first one. It all worked as intended and runs as smooth as the other gears. However when I tried the second one it was a bit lumpy and then I noticed that although it seemed to fit okay between the frames it had splayed them slightly so I popped it back in the lathe and skimmed both ends slightly and on the next try it ran just like the first one. Now I really am a happy bunny.
Just for scale this is one of the gears again a 5p piece. They are very small.
Shop Made MOD 0.3 Final Drive Gear
Once again, I would like to sincerely thank all who have contributed to my getting this far.
From identifying the gearboxes that I bought at Stafford, to working out via information provided by fellow members that it was a 29 tooth Mod 0.3 gear that I needed to buy or make and all the helpful advice on both the theory and practical aspects of gear cutting. It really is much appreciated.
Later in the day yesterday I stripped down the spin indexer and took the division plate off. I mounted it on the dividing head chuck of my Proxxon mini drill and reamed out all of the holes to 5mm.
Then, having ensured that the locking collar was tight on the spin indexer and the Y table locked to ensure a consistent depth of cut, I had another go using the opposite end of my aluminium stub.
All went swimmingly and I ended up with a perfect gear.
Test Cut no 2 – Mod 0.3
Now I need to do it for real to produce the missing final drive gears for my two Shogun Gearboxes.
Buoyed by my small successes with the worm and wheel yesterday I decided to take the plunge and set up the mill to actually cut an involute gear.
I took Brian’s advice and did a test cut on a stub of aluminium to take the burrs off and bed in the cutter.
It has to be said I made some mistakes but it was a great learning opportunity and as a number of fellow members asked on the GOG online modellers meeting I recorded a video of the process. I recorded the whole thing which is about 12 minutes long and I suspect may be a little boring in the middle where I was just repeating the cuts.
Here’s a list of the things I did wrong/didn’t do that I should have etc.
1. I didn’t fully tighten the locking collar when I refitted the 3D printed division plate which mean that after a few cuts it stopped moving and I lost my index position.
2. Although I checked some of the index pin holes in the division plate, I didn’t check them all and that came back to bite me as I struggled to get the pin in some of the holes properly this didn’t really affect the indexing too much but it did make it really hard to get the pin out between cuts
3. I forgot to lock the Y axis of the mill table which meant that the cutter eventually pushed away from the workpiece a little.
Taking all that into account I did manage to cut a gear (ish)
The other ‘side’ isn’t quite so pretty…
Here is the video for those who are interested in the how.
