Garden Railway Forum

GTB wrote: ↑Sun Aug 21, 2022 2:18 pm

philipy wrote: ↑Sat Aug 20, 2022 10:50 am My only reason for looking at something other than the N20 gearmotors is that the one in my "steam powered potting shed " can barely pull itself along, not sure why.

I hadn't realised that little engine was so low powered. Does it just sit there and quiver if loaded up, or does it slip and fail to proceed?

With fully charged batteries it crawls a few yards and then stops and doesn't want to know anymore. I'm thinking the mechanical resistance is such that the motor is not far off stalling all the time,and drains the batteries to quickly.

I think the answer may have several prongs, and one of them is the wheels, both the material and more importantly the problem of keeping the drivers parallel to each other. Because the motor output shaft is rather too short, I had to print extended sleeves on the back of the wheels and they really aren't accurate enough. So they are constantly both under and over gauge and bind on the rails all the time.

GTB wrote: ↑Sun Aug 21, 2022 2:18 pm https://gardenrails.org/viewtopic.php?f=37&t=12453

The gang motor weighs 260g and with the driven axle leading (worst case) managed 34g drawbar pull. The train weighed 663g and had a rolling resistance of 22g. Well within it's capability on my more or less flat track, but it would have slipped to a halt on a 1:50 grade. If both axles were powered, it would have just managed the train on a 1:30 grade.

The gang motor is fitted with a Como 951D601/6V micro gearmotor (I now use Pololu #998 6V 50:1 gearmotors). Gear ratio is 60:1 giving 300rpm at 6V at the output. The final drive is 1:1, using a pair of 0.5mod 20 tooth mitre gears (I now use a pair of 0.5mod 16T mitre gears). The final drive gearbox is milled out of a block of brass, but would probably be possible to print. I can post the back of the envelope sketch I use if needed. I work in 45 mm gauge, but the gearbox is only 21 mm wide so should fit a 32mm gauge wheelset. Probably not enough space left though, to couple the axles by chain for all wheel drive.

The gang motor has 20 mm steel wheels, from IPE I think, leftover from some early Ezee kits before I started turning my own wheels. The battery is 4 x Eneloop cells (4.8V), which gives a scale speed of 11 mph, so a 30:1 gearmotor would give you 20+mph.

Thanks for that info. I wouldn't mind seeing gearbox your sketch, please. No point in reinventing the wheel so to speak.

philipy wrote: ↑Sat Aug 20, 2022 10:50 am
( Still can't work out how to make the roof go up and down though!! )

GTB wrote: ↑Sun Aug 21, 2022 2:18 pm The first major model railway exhibition in Melbourne for 3 years was this weekend and one of the things I saw was a HO scale bike rider furiously pedalling along a road. Nothing is impossible it would seem........

I think it would be possible to use a couple of the miniature linear rc servos used by aeromodellers (look on ebay) and some sort of linkage to raise the roof. They don't take up a lot of space, but seem to be powerful, a friend uses them to operate signals in HO.

Working out how to animate the driver to walk up, open the door and lift the roof might be a bit more of a challenge.......

Well, many, many years ago, I did create a 4mm farm labourer who bent over and stuck his pitchfork into a pile of hay ( chopped sisal string) and then heaved it up on to the top of a threshing engine. Sadly it was before the days of commonly available video so I only have one slightly fuzzy still photo, but it kept the exhibition punters fascinated for hours, especially the kids! He was operated by a fairly complex cam mechanism which bent him over, pulled his arms back and jabbed down, then flicked back up!
Anyway, I do have an idea in mind for the roof raising, but thats a way down the line yet. No point in raising the roof if it won't move! Servo's would obviously work but with nowhere to hide them it would rather spoil the effect.

Ive been digging around looking for more pictures, as you do!

Came across this site with a catalogue for sale:https://fahrzeuge.dorotheum.com/en/l/2332285/
Sadly the triple picture is just too small to get any great detail when enlarged, but it does show it in ex-works condition.

I also came across this example as a static exhibit in Patagonia!! The wheels on the skips don't look man enough to hold it off the ground, let alone rough quarry work.
What I was actually looking for is door detail. The drawings all seem to show hinged doors and the Patagonia loco definitely has hinges on the 2nd picture. However, other pictures all appear show slightly wider, sliding doors, but I can't mke it out for sure. Any thoughts anyone?

I think I'm beginning to understand the doors.
The earliest drawings/photo's indicate a smallish hinged door, but subsequent vesrions seem to have sliding doors which are either single or double. I suspect that this is due to the later use of physically larger engines and the need to be able to access them for maintenance.The coloured picture of a wooden bodied version definately has hinged doors, but it looks to me to be a modern restoration/rebuild so can't be taken as indicative of a working loco from the 20's/30's.
I'm thinking that the drawings showing the single hinged door will be the easiest/strongest to model since the door can be an integral part of the side if modelled closed, and that in turn will make the engine less visible and hide some of the imperfections it will undoubtedly have!

philipy wrote: ↑Sun Aug 21, 2022 3:36 pm I wouldn't mind seeing gearbox your sketch, please. No point in reinventing the wheel so to speak.

Herewith, one photo and one back of the envelope pencil sketch. This is the nearest I ever get to doing a drawing, it's basically just to remind me of the dimensions when machining.

The photo shows the drive fitted in the the gang motor, which was the first one I built and the only one with 20T gears. Since then I've changed to the final drive in the sketch, with 16T gears. The 0.5mod 16T mitre gears come from RS Components, stock no. 182-7986, about A$8 for a packet of 5.....


The sketch shows the 16T gear version, as it's slightly smaller. Makes no difference to power output, but it is only 21mm wide, which may allow just enough extra space for chain coupling the axles in 32mm gauge.


The last photo is the test train I ran the other day. No movie I'm afraid, my status as a card carrying Luddite hasn't changed.


Regards,
Graeme

I'll stay out of the mechanical chat, way beyond me, but lovely to see this progressing! That red AD's great, excellent views of the interior - and yes, the yellow skips look like shopping trolleys on those little wheels!

I've got no idea if it will work as a long-term solution, they may just ping/slide/snap off, but I've recently replaced the missing traction tyres on my Faller railbus with children's "loom bands" - this sort of thing: https://www.amazon.co.uk/Refill-Bands-c ... 53503&th=1

They've only had one trundle up the line so far - but so far, so good... I think Faller wheels are 21mm diameter, reckon the bands would stretch larger though.

By the way Graeme, I think your description of the loco as a mobile bread bin was most unfair - it looks more like a toaster...

Cheers all,

Andrew.

Thanks Graeme. In principle thats what I've been aiming at, but the dims will be useful to check what I've got.

Your choice of RS for gears is interesting. I did look at RS but at £3.54 for the 5 gears, plus £4-95 p&P, + Vat, the bottom line was over £10. I don't need 5 gears and I got one pair from MotionCo for £4-95 post free.

I assume that the brass sleeve on the axle adjacent to the gear is simply a spacer to keep the gear mesh?

Andrew wrote: ↑Tue Aug 23, 2022 2:22 pm I think your description of the loco as a mobile bread bin was most unfair - it looks more like a toaster...

Can't say I've ever seen a toaster with a lid. Look up the word 'Esky'...........

Graeme

philipy wrote: ↑Tue Aug 23, 2022 2:51 pm I assume that the brass sleeve on the axle adjacent to the gear is simply a spacer to keep the gear mesh?

I wondered how much that den of thieves in Westminster would manage to push up the cost of the gears. Here in Oz, RS sent stuff out post free until covid screwed up the supply chains. Now I batch orders to get over the p&p threshold. There's not a lot of choice here for buying small plastic gears of decent quality.

Yes, the brass sleeve is a piece of K&S tube used as a spacer to stop the axle slopping around and affecting the gear mesh. There's also a thin brass washer on the other side in the current design, to reduce friction from the gear boss rubbing on the gearbox.

Regards,
Graeme

GTB wrote: ↑Tue Aug 23, 2022 11:58 pm
Here in Oz, RS sent stuff out post free until covid screwed up the supply chains.

RS used to be post free here as well, although they actually stopped that before Covid. I must admit that I did used to push it a bit ( as I'm sure others must have done), just ordering a couple of resistors, or whatever, whenever I needed and getting them delivered overnight. The paperwork alone must have cost more than the value of the order, let alone adding in the free delivery!

I thought it would be a good idea to separate my build notes from Andrews original "Off Topic" thread, so I'll split that thread and then continue with the build below.
The pictures and drawings are still in the original thread at :
https://gardenrails.org/forum/viewtopic ... 35#p170035

A kit of bits for the body and underframe....

Nice to see the work being done on others making them! I've been collecting the drawings and research with a view to drawing one up myself to print on my own machine but alas not got round to it yet.

Whk2000 wrote: ↑Tue Aug 30, 2022 10:49 pm Nice to see the work being done on others making them! I've been collecting the drawings and research with a view to drawing one up myself to print on my own machine but alas not got round to it yet.

Ah, but you've provided the inspiratin, firstly with your Festipedia article, and then with your drawings!

It's looking good Philip, great progress!

My thanks to both of you. I wouldn't have known of the existence of this beastie if Andrew hadn't posted about it and I wouldn't have had plans and pictures to work from without your input, Whk2000. I must admit I felt a little bit guilty in pinching your research, I know how time consuming that can be. So my thanks to you for your generosity.

Anyway, some progress although not as much as I had hoped, for several reasons: I had to redraw/reprint a few bits due to errors. Getting the batteries in proved to be a bit of a pain until I had a bright idea ( more about that in a bit). The post strikes have delayed delivery of 3mm axle bushes ( I thought I had some but they turned out to be 1/8" GRRR!) and Micron have put me on the waiting list for a 603!

Sooo... this is where I am at the mo.
1) The body is mostly put together and had a prelim rub down/tidy up. The battery box is in the LH end and has a cover to be screwed on in due course.
2) Getting the batteries in was a trial. They sit in 2 rows, a three above a two but not tight, so every time I tried to do anything they slipped and went out of line and didn't fit in. I tried tape, and glue, and all sorts but they would NOT stay where I put them. Then I had my bright idea and printed a 'mould' by extending walls up from the drawing of the inside face of the compartment end. This holds the batteries in the correct alignment and automatically spaces them! Then a glue gun locked them in place and allowed me to solder the tags, and now I have a nice rigid custom shape battery pack which is what you can see in the 'mould' at the RHS.
3) The roof is printed.
4) The chasis is done and the motor mounted. The motor can't actually be seen in the picture because I've printed a 1mm thick cover for it to try to protect the very fine gearbox from the worst track debris.
5) I've also resin printed the fuel tank and a rudimentary engine ( not in picture).

Just a quick update.
Unfortunately, life has got in the way of 'art' for the last couple of weeks, but this afternoon I did have it running up and down a length of track with quite satisfactory results. Unfortunately it only has a simple on/off switch atm because it isn't worth doing anything fancy until Andy can sell me a new Micron Rx.

If you remember, my original plan was to to use a 30rpm N20 Gearmotor, but trials showed that was too slow even for this wee beastie, so I swapped it for a similar 100rpm version. Going flat out ( ie no motor speed control) it is now perhaps just a tiny bit fast, but it should just about be spot on with the rc control, in due course.

No pictures with this post because nothing worth showing. Hopefully, there should be some proper progress in the next few days, so watch this space.

philipy wrote: ↑Fri Sep 16, 2022 5:04 pm If you remember, my original plan was to to use a 30rpm N20 Gearmotor, but trials showed that was too slow even for this wee beastie, so I swapped it for a similar 100rpm version. Going flat out ( ie no motor speed control) it is now perhaps just a tiny bit fast, but it should just about be spot on with the rc control, in due course.

I saw the chassis photo in another thread and it looks very workmanlike. Sounds like you are happy with how it runs.

Running a small loco at 30rpm at the wheels means it would take about 20 mins for one circuit of my backyard at a scale speed of about 1.5 mph, with the motor doing an imitation of a dentist's drill. In wet weather the snails would be overtaking it on the outside.....

Even back in my days working in HO, I never understood why british modellers insisted on slow running by using very high reduction gear boxes with the motor screaming its head off at max. revs. I like things to run nice and quiet and set my mechs up with lower reduction ratios and run the motor at half the rated voltage. The motors don't wear out as fast and now with battery power I don't need to find space for as many cells, especially in the small railmotors I like to build.

What Rx were you planning on using? I bought a couple of the RSC version of the new Micron MR603a, one of which was intended for use in a railmotor. What doesn't show in most of the photos is the electrolytic capacitor on the back of the board, which made it too large to fit in the intended model.

Regards,
Graeme

GTB wrote: ↑Sun Sep 18, 2022 5:21 am

What Rx were you planning on using? I bought a couple of the RSC version of the new Micron MR603a, one of which was intended for use in a railmotor. What doesn't show in most of the photos is the electrolytic capacitor on the back of the board, which made it too large to fit in the intended model.

I was planning on using a Micron 603b, but I'm on a waiting list of unknown length for delivery, so yesterday morning I dropped Andy a line asking about his thoughts for using a Deltang 41/43/45 instead.

Interesting, your comment about the capacitor. I must admit that I had wondered why the board dims had such a large figure ( 10mm) for the thickness, but that would explain it. In my works layout planning for this A-D I had simply drawn a rectangular box of the correct o/a dims and worked with that, so it doesn't bother me as such this time around because I have the room.

The 'B' is better, in this respect :

I have boards you can use with the smaller Deltang receivers..
A 'bigger' ESC, and a regulator for the supply to the receiver. These allow you to go up to a '2S' battery, and more than the 500mA limit of the receiver's ESC.

Phil.P

philipy wrote: ↑Fri Sep 16, 2022 5:04 pm Unfortunately, life has got in the way of 'art' for the last couple of weeks

I know that feeling...

philipy wrote: ↑Fri Sep 16, 2022 5:04 pm Hopefully, there should be some proper progress in the next few days, so watch this space.

Looking forward to it! Sounds great so far...