Giles

This visitor appeared two days ago- not very welcome, but interesting. Had a bath in our pond as well! sorry about the rubbish phone pic!

The bogie mount and fixing.... something I've been thinking about for some time. This will allow easy removal of the bogies, and give 3-pont suspension.

One of the little power bogies under test....

And makes two.......

The first bogie is now fully assembled, and fitted with its PLA printed bolster. The bolster has a hole through to accommodate the gearmotor at exactly the right position and angle, and also has a spheres the top to act as a pivot, and as a fixing (think snap fastening)

Everyone's going to get very bored with this...... however, things progress slowly. Today I made sure all was clean, and blackened the frames and epoxied the spring/horn assemblies on , which was very easy with the three holes to locate them. Everyone's going to get very bored with this...... however, things progress slowly. Today I made sure all was clean, and blackened the frames and epoxied the spring/horn assemblies on , which was very easy with the three holes to locate them. Next was etch primer, cutting axles and pressing wheels and a bevel gear on....... Thus far, I'm extremely happy with things - loving the printer, and how much it helps!

Appropriate bevel gears are obtainable from Technobots at about 45p each. I find that generally the N20s perform very well under radio control, reprogrammed with an output of 60Hz - information not much use for 2-rail running! Nice job!

Two set of bogies, together with bearings, rods, cranks etc., so we're coming along.

When I started, I built my first vehicle with single-wheel drive for cornering. It performed poorly, and I quickly converted it to a fixed driving axle (The only exception being a fork-lift which has a differential.). You need both rear wheels driven, and the half dozen 4mm vehicles and 15 or so 7mm, all corner absolutely fine.......

I think you'll find lifting the radio gear from a toy won't give you anything like the finesse you would like. I would strongly suggest you use a Deltang Rx41- 22, configured for loco use, as you don't need steering. This would enable you to use a single small transmitter (TX-22), and select up to 12 vehicles (or locos), and gives very nice inertia control as well. Importantly, you can also program the receivers pulse width modulation output (frequency) which makes a massive amount of difference as to how the motor performs, particularly at slow speed.

The first two cranks cut on the Stepcraft. they are of course slightly different for all locos, so one starts again with the drawing and toolpath - moreover, because I want a good fit on the 2mm axles, and invariably it is a different cutter, I have to do a series of test holes fractionally adjusting the size till I get a good fit on the rod I've got. Then I can try actually cutting one, only to ralise Ive made an error in the cutting path, and stop the machine, reprogram and start again..... so it takes time. These then take 17 minutes each actual cutting time, so ling as nothing goes wrong. They will have 14BA bolts silver soldered in from the back (after tapping)

Thank you Nye I use DesignSpark Mechanical, and draw the curve in plan, copy it to the thickness of the spring (0.22 in this instance), close the ends, and Pull the area up by 1.4 or whatever to form the leaf. I then copy the (lower) surface, move the copy off about 0.02mm or so to leave a small gap, and then pull that to form the next spring, but then Pull (push) the ends to shorten the new curved leaf to whatever length I want. Rinse and repeat..... I don't know if it's the best or right way to do it, but it was quite straightforward to do.....

The loco was built for the Ashanti Mines, and had a 6 cylinder Gardener driving a 2-speed epicyclic gearbox and a dog-clutch reverse on the final shaft. It was later fitted with a diff. 5' across the buffer beams, standing 9' high and 3' between axles. Diesel and water tanks behind the cab, and a small 12 gallon service tank at the front of the cab. This is one of the spring assemblies I have drawn and printed with a Mars 2 Pro Bogie frames from nickel silver, CNCd on the Stepcraft.

There may be an additional loco for The Sparrow - because you can never have enough, and I've always been interested in this one. There's limited information on it - a Proposed G.A. from Bagnall, and about four photos of the first loco built, before it was shipped to Africa. When you start getting into it, you realise there are a lot of differences between the Proposal, and the As-Built - not unreasonably. I've therefore spent a little time sorting this out as best I can, and the results are probably not very far off. Edited with updated drawing.....

Quite right - 100th of a millimeter!

A Bagnall Ashanti Mines diesel.... Monkeys - I'm surprised all yours aren't replicating themselves by now!

Forgive a complete tyro with this type of printing - but six months ago, I received a Mars 2 Pro printer for my birthday, courtesy of Di - of course! It has laid dormant partly because I hadn't the immediate need, and partly because I found the thought slightly intimidating. However, I have been looking at a loco that caught my interest, and a couple of parts really need to be printed, so I took the bull by the horns, so to speak...... I spent a morning on Design Spark Mechanical and drew up the necessary, then downloaded Chitubox and slicedit etc..., and today had a look at what I had to do with the printer. It reality it was all straight forward, and I went straight to printing 8 of my spring assemblies rather than their Rook trial piece. I went for 1 micron, as I want the highest level of detail (that is the point of the machine for me) and pressed Go. Of course it was only realistic to expect the print to fail. The question was at what point and in what way....... To my great joy, all eight turned out perfectly, blemish free.... what a machine, and an addition to the workshop!

I shall put the Bracknell show in the diary! I had spotted the coal-guards - a very nice touch - but I completely missed that you had shortened the front end..... I think the saddle tank is absolutely delightful - a very nicely proportioned and good looking loco. My Slomo in on September's list, I am assured - but then it has to make it's way over here! Meanwhile I very much look forward to seeing your layout end of October! Giles

I think your right.... it does make a lot of difference....... I'll have you know that this is entirely your fault! I found your work and layout inspiring in a way I have never found in 16mm before....

Good to know..... thank you! I've managed to sort the regulator which wasn't closing properly. Cleaning up the cone was easy enough to do with some polish, and I managed to clean the internal seat/bore by soaking a cocktail stick in Duraglit wadding for a while, and reaming it out with the polish soaked pointy end! That worked, and it now seats perfectly. The smokebox was pop-riveted on, so I drilled them out - breaking through the side of the saddle in the process (well, the rivet had done that, and my drill followed it nicely!). I then had to open that out, leaving a gaping hole, tap it M4, put a brass bolt in and silver solder it in all round. This was then sculpted back to profile. All a pain, but ok. New, tapped holes were made in a much better position to enable the bolting from the underside..... while I was at it, I was able to rotate the dart to vertical, which had been annoying me. Smoke box is now repainted. The new boiler is fitted, which was more of a faff than I was expecting, as hole centres were all slightly different etc....., but job done. The gas filler valve leaks when you fill, so I've ordered a new valve to see if that cures it..

I've not tried cutting styrene, but I do cut acrylic (perspex and Trotec) from time to time, and I've tried a reasonable number of variations, and I only have any real success with high speed feed rates - 30mm per second 1800mm per minute - anything much slower and I get a build-up of melted plastic that wrecks the job. This gives me a nice clean cut. I would observe, generally, that I chose the Stepcraft over others because it looked to be the most rigid machine of its type - and I think that has been true. Certainly I've not regretted the choice. Like all things, there has been a learning curve, but it has been such a revolution to my modelling...

You are absolutely right! My mistake!

Ah.... I posted having mis-read your speeds - sorry about that! So I cut at around 15mm per minute with the 0.8mm I also run the spindle at between 16 and 20,000 rpm Best Giles

Not cheeky at all...... I will confirm when I'm on the computer for accuracy, but where possible I use a 1.6 dia D bit for everything I can, and that cuts at around 0.3mm per pass, and about 0.3mm per second, and where I have to go smaller, I use a 0.8mm D bit, and run it at around 0.2 per pass and about 0.25mm per second. These are the cheap Chinese carbide tools sold for PCB work, at around £5 for 10. There is a reasonable mortality rate for the 0.8mm ones (sometimes one will last three or four weeks, other times I will break three in a day....) but the 1.6 are much more resilient. They don't like the work moving! When cutting small pieces, I always program a tab to hold it in place and prevent it from breaking free - as that is guaranteed to snap a tool. I generally get on less well with conventional end mills for this sort of work (non-ferrous profiling)

Quarry Hunslet (7mm) chassis parts 7mm Peckett milled chassis