Any Question Answered

[Nigelcliffe]

PWM controllers, using cheap PWM devices from ebay and the like, were discussed in an article in the 2mm Magazine in August 2020 written by James Batchelor .   Worth a read, as the article builds a very effective and cheap DC controller with a meter attached.  

 

 

The issue of "not going down to zero" is whether the PWM device output can get to a zero width pulse or not.  Some do, some do not.   
If it doesn't go all the way to zero, then the quick solution is two or four diodes added to the output to remove the bottom 0.7v (one pair of diodes) or 1.4v (two pairs of diodes) from the output.  It also drops the top-voltage by the same amount.  

 

 

- Nigel

[Donw]

Good idea that Nigel otherwise reducing the supply voltage affects the top speed more than the slow speed

 

Don

[John Brenchley]

13 hours ago, Nigelcliffe said:

PWM controllers, using cheap PWM devices from ebay and the like, were discussed in an article in the 2mm Magazine in August 2020 written by James Batchelor .   Worth a read, as the article builds a very effective and cheap DC controller with a meter attached.  

 

 

The issue of "not going down to zero" is whether the PWM device output can get to a zero width pulse or not.  Some do, some do not.   
If it doesn't go all the way to zero, then the quick solution is two or four diodes added to the output to remove the bottom 0.7v (one pair of diodes) or 1.4v (two pairs of diodes) from the output.  It also drops the top-voltage by the same amount.  

 

 

- Nigel

 

Thanks Nigel for sending a reminder of that article 

 

A straightforward description and some simple wiring diagrams.

 

John

[Crosland]

Diodes will only affect the voltage, not the pulse width.

[queensquare]

I'm working on a couple of 3D print L&Y D62 wagons. They are designed for the L&Y 12' chassis but I'm struggling to get my head around the brake gear. Are there any instructions for these - and indeed the other L&Y etches.

 

thanks in advance, Jerry

[Sithlord75]

Hi Jerry,

 

I would say have a look at the L&Y wagon page at the L&Y Society and see what you can determine.  It what I did with the LNWR etches.

 

Cheers

Kevin

[Chris Higgs]

11 hours ago, queensquare said:

I'm working on a couple of 3D print L&Y D62 wagons. They are designed for the L&Y 12' chassis but I'm struggling to get my head around the brake gear. Are there any instructions for these - and indeed the other L&Y etches.

 

thanks in advance, Jerry

 

L&Y fitted brakegear is basically the same idea as GNR/LNER fitted underframes, except it only has 4 brake shoes instead of 8. So 2 V-Hangers on one side, one on the other. If building a steel solebar underframe, use the V hangers attached to the underframe, if wooden then cut these off and use those on the solebar overlays (parts 5a and 5b) instead. The Diagram 62 Covered Goods Wagon were of this type.

 

So for a fitted underfame, use the part marked 2 fitted, together with the central rodding part below it and the two parts looking like coat hangers which are between the solebars on the etch. Brake cylinder in the hole provided on part 2, although I suspect the Association turned ones are not the right size for a L&Y prototype, they look rather larger in photos.

 

For unfitted wagons use the part marked 2 unfitted, these only had brakeblocks on one side.

 

Some LYR 10'6" wagons had a more normal Morton style underframe, the etch does not cover those.  The Diagram 68: 20 ton Coal Wagons had a different variant of the underframe and again the etch does not cover those.

 

Some pictures here: https://lyrs.org.uk/wagons/ but if you want more detail you will need to buy the LYRS books.

 

Chris 

 

[queensquare]

20 minutes ago, Chris Higgs said:

 

L&Y fitted brakegear is basically the same idea as GNR/LNER fitted underframes, except it only has 4 brake shoes instead of 8. So 2 V-Hangers on one side, one on the other. If building a steel solebar underframe, use the V hangers attached to the underframe, if wooden then cut these off and use those on the solebar overlays (parts 5a and 5b) instead. The Diagram 62 Covered Goods Wagon were of this type.

 

So for a fitted underfame, use the part marked 2 fitted, together with the central rodding part below it and the two parts looking like coat hangers which are between the solebars on the etch. Brake cylinder in the hole provided on part 2, although I suspect the Association turned ones are not the right size for a L&Y prototype, they look rather larger in photos.

 

For unfitted wagons use the part marked 2 unfitted, these only had brakeblocks on one side.

 

Some LYR 10'6" wagons had a more normal Morton style underframe, the etch does not cover those.  The Diagram 68: 20 ton Coal Wagons had a different variant of the underframe and again the etch does not cover those.

 

Some pictures here: https://lyrs.org.uk/wagons/ but if you want more detail you will need to buy the LYRS books.

 

Chris 

 

 

Thanks Chris,

 

Jerry

[tapdieuk]

I am trying to get DG's to uncouple with 8mm neodymium magnets, on a moverable arm under the track. 

I am with in 4mm of the underside of the track and still reliable success.

How does others do? 

[nick_bastable]

31 minutes ago, tapdieuk said:

I am trying to get DG's to uncouple with 8mm neodymium magnets, on a moverable arm under the track. 

I am with in 4mm of the underside of the track and still reliable success.

How does others do? 

work for me although I have stacked and glued the magnets to make reliable operation

 

Nick B

[Richard Hall]

3 minutes ago, nick_bastable said:

work for me although I have stacked and glued the magnets to make reliable operation

 

Nick B

 

My solution to the same problem.  Magnets are glued to a brass hinge which falls away under its own weight and is lifted up against the bottom of the baseboard by the servo arm: if the servo or its control unit fail (which will only happen at an exhibition) I can stick my hand under the baseboard and uncouple trains that way.  This uncoupler serves two parallel roads.

 

 

[Ian Morgan]

I found uncoupling no problem with a single magnet - the problem was ensuring not uncoupling when lowered. Eventually I had to arrange for a full 90 degrees of movement to force the magnetic field to end up parallel to the track rather then vertically up through it when lowered.

 

Note, I have three magnets on the arm that act on three parallel tracks, so I have 9 uncoupling locations for just 3 servos.

 

[2mmMark]

5 hours ago, tapdieuk said:

I am trying to get DG's to uncouple with 8mm neodymium magnets, on a moverable arm under the track. 

I am with in 4mm of the underside of the track and still reliable success.

How does others do? 

The sliding magnet system as described in the April 2007 2mm Magazine worked perfectly all weekend on British Oak.

 

I use 6mm dia by 6mm long cylindrical magnets through 4mm of baseboard/trackbed + 1.8mm of track.  Neodymium magnets don't lose any noticeable amount of magnetism.

Mark

[Moria15]

Hi there.. apologies for a really stupid question..  but was looking at the Pannier replacement chassis kit on the shop site and it says in the instruction sheet  8 or 10mm coreless..  however, when I look at the motors section, there only seems to be 6 or 7mm coreless motors available.  I'm actually assuming a 6 or 7mm one would be fine, as long as the shaft is sleeved to the right diameter?

 

In addition, it says the chassis is a replacement for the Farish 57xx...   has anyone used it in a Dapol 57xx ?

 

Thanks in advance.

 

Graham

[Ian Smith]

3 hours ago, Moria15 said:

Hi there.. apologies for a really stupid question..  but was looking at the Pannier replacement chassis kit on the shop site and it says in the instruction sheet  8 or 10mm coreless..  however, when I look at the motors section, there only seems to be 6 or 7mm coreless motors available.  I'm actually assuming a 6 or 7mm one would be fine, as long as the shaft is sleeved to the right diameter?

 

In addition, it says the chassis is a replacement for the Farish 57xx...   has anyone used it in a Dapol 57xx ?

 

Thanks in advance.

 

Graham

Graham,

Hopefully someone more qualified than me will be along soon to better answer your questions. However my take is that the chassis is the best part of 10 years old now, in that time Dapol introduced a 57xx (possibly more dimensionally accurate with potentially a different wheelbase? - I don’t know as I haven’t got a Dapol version) in actual fact I haven’t got very much of a Farish one as it received serious cosmetic surgery to convert it into an 1854 class saddle tank 🤣.  Also in the intervening years the old Maxon 10mm diameter motor has been dropped from the shops, with recently stocked 6mm and 7mm Tramfabriek ones being introduced in its stead.  My butchered example has I think a 12mm diameter Nigel Lawton coreless motor in it (haven’t had the top off since it was built so really can’t remember).  My two latest locos (517 and steam railmotor) both utilise the 6mm motor from the shop, and run quite nicely (on DC - I’m an old fashioned analogue guy), the rest of my “fleet” has Nigel Lawton 8mm diameter motors fitted.

In short, the 6 or 7 mm motors should be ok (but would need shafts sleeving), especially if using the fold up gearbox bit (if I was building another I’d dispense with it). For info, the 7mm one is double ended so perhaps could have a flywheel put on the other end (if there’s room in the body). 
Hope that is helpful

Ian

[Moria15]

54 minutes ago, Ian Smith said:

Graham,

Hopefully someone more qualified than me will be along soon to better answer your questions. However my take is that the chassis is the best part of 10 years old now, in that time Dapol introduced a 57xx (possibly more dimensionally accurate with potentially a different wheelbase? - I don’t know as I haven’t got a Dapol version) in actual fact I haven’t got very much of a Farish one as it received serious cosmetic surgery to convert it into an 1854 class saddle tank 🤣.  Also in the intervening years the old Maxon 10mm diameter motor has been dropped from the shops, with recently stocked 6mm and 7mm Tramfabriek ones being introduced in its stead.  My butchered example has I think a 12mm diameter Nigel Lawton coreless motor in it (haven’t had the top off since it was built so really can’t remember).  My two latest locos (517 and steam railmotor) both utilise the 6mm motor from the shop, and run quite nicely (on DC - I’m an old fashioned analogue guy), the rest of my “fleet” has Nigel Lawton 8mm diameter motors fitted.

In short, the 6 or 7 mm motors should be ok (but would need shafts sleeving), especially if using the fold up gearbox bit (if I was building another I’d dispense with it). For info, the 7mm one is double ended so perhaps could have a flywheel put on the other end (if there’s room in the body). 
Hope that is helpful

Ian

 

Ian, thanks very much.  I was wondering if the coreless ones were tramfabriek ones, so that's answered that.

 

I am DCC so the smallest motor is going to be an advantage, even if by 1mm or so.

 

Unfortunately, I cannot compare the Farish and Dapol as I only have the Dapol one, which oddly enough, I was planning to turn into a saddle tank as well so I guess the body is probably going to get some serious work anyway....    Whilst I model 1920's GWR in N-gauge I'm moving back in time for my first experiments in 2mm and actually a saddle tank is a bit modern for that, but certainly much closer to period :)

 

I may even have to play with outside cranks, but it's to get something built and running...   mostly I want to be playing with track that is dual 9.42 and 14mm gauge ultimately with 8' and 9' drivers :)

 

Regards

 

Graham

Edited July 1, 2022 by Moria15

[Ian Smith]

6 hours ago, Moria15 said:

I may even have to play with outside cranks, but it's to get something built and running...   mostly I want to be playing with track that is dual 9.42 and 14mm gauge ultimately with 8' and 9' drivers :)

 

Graham,

Would love to see a bit of mixed gauge GWR.  I gave serious consideration to doing something along those lines for a DJLC (Diamond Jubilee Layout Challenge) but early on it looked like someone else was doing it for their entry.  Unfortunately, it seemed that that particular entry fell by the wayside.

 

When I get bored of making stock for Modbury perhaps I ought to give it a go - I have a set of coaches that were originally built as broad gauge convertible stock so doing the artwork and making broad gauge underframes for them would give me an easy way in. 😂  If I ever did build something mixed gauge it would be c. 1890 as I have virtually no interest in the early Gooch era broad gauge.  I quite like the "modernised" South Devon Railway 4-4-0 tanks, and the Rover's were magnificent.

 

Ian

[Chris Higgs]

23 hours ago, Moria15 said:

Hi there.. apologies for a really stupid question..  but was looking at the Pannier replacement chassis kit on the shop site and it says in the instruction sheet  8 or 10mm coreless..  however, when I look at the motors section, there only seems to be 6 or 7mm coreless motors available.  I'm actually assuming a 6 or 7mm one would be fine, as long as the shaft is sleeved to the right diameter?

 

In addition, it says the chassis is a replacement for the Farish 57xx...   has anyone used it in a Dapol 57xx ?

 

Thanks in advance.

 

Graham

 

As designer of said chassis, I have not built it with a Dapol body but it looked like it would be OK. Personally I think I would drive the loco off the rear axle if using the Dapol body. Although that makes the project more daunting.

 

The Dapol body has the same (correct) wheelbase as the Farish, but shows up how the Farish body is in fact overscale.  Just to warn you, getting the original motor out of a Dapol body is the very devil. The Bachmann/Farish 64XX is a better moulding than either of them IMO.

 

There were no 6 or 7mm coreless motors around when I wrote the instructions. Personally, I think 6mm is going to be too puny, but would certainly help with providing space for weight as the plastic Dapol body is a whole lot lighter than the Farish.

 

Chris

 

 

 

Edited July 2, 2022 by Chris Higgs

[Moria15]

33 minutes ago, Chris Higgs said:

 

As designer of said chassis, I have not built it with a Dapol body but it looked like it would be OK. Personally I think I would drive the loco off the rear axle if using the Dapol body. Although that makes the project more daunting.

 

The Dapol body has the same (correct) wheelbase as the Farish, but shows up how the Farish body is in fact overscale.  Just to warn you, getting the original motor out of a Dapol body is the very devil. The Bachmann/Farish 64XX is a better moulding than either of them IMO.

 

There were no 6 or 7mm coreless motors around when I wrote the instructions. Personally, I think 6mm is going to be too puny, but would certainly help with providing space for weight as the plastic Dapol body is a whole lot lighter than the Farish.

 

Chris

 

 

 

 

Thanks very much Chris.   Lots to think about, but another step forward.

 

Thank you again.

 

Graham

[Simon D.]

 

Can any of our dental practitioners recommend a source of fine acrylic repair material as suggested in this video from a fellow American dentist modeller please?  He mixes the resin with fairly thick CA to use as a filler.  The brand he recommends does not seem to be readily available in the UK: Dentsply repair material lab powder 454 pink free flow.  Is there an equivalent?

 

Interestingly he doesn't recommend the resin for casting.

 

Cheers

 

 

[CF MRC]

This would be equivalent:

https://panadent.co.uk/shop/dentsply-degudent-rapid-repair-powder/

The methyl methacrylate beads would simply be acting as a filler within the cyanoacrylate. 

 

Probably worth speaking nicely to a local denture repair  technician: who would use  similar materials in bulk. You would not want a ‘veined’ acrylic!
 

Tim
 

 

[Simon D.]

Many thanks Tim.

[2mmMark]

Baking soda makes an excellent filler when mixed with cyanoacrylate adhesive. Non-food grade soda is available cheaply as a cleaning product. 

 

 

Mark

[Simon D.]

Thanks Mark.

 

Much less pricey!

[CF MRC]

In his video the chap indicates that the acrylic works better than baking soda. 
 

Tim