DCC Uncoupling with servos?

[deepfat]

Friends

I want to build some sort of ramp (maybe disguised as a sack barrow) that rises up a bit when active to act as an uncoupler, and control that form DCC as an accessory like a point.  I was thinking of using servos for this (I need about 16 of these) .  I know you can modify stock to respond to magnets but they clunky and the Kaydee doesn't look right for era 3/4. So has anyone done this and what interface did you use between the servos and the DCC system

Thanks in advance  

PS for reference I am on Roco Z21+booster controlled though iTrain

[ITG]

Whilst I haven’t yet tried to connect the uncouplers I use to DCC (I’ve previously used them via a 12v DC push-button on track layout panel), I’m pretty sure it can be done, as all you’d be doing is replacing the push button with a DCC command via an accessory decoder.

 

http://www.heathcote-electronics.co.uk/uncoupler_oo_gauge.html

in fact, I think I may have asked Heathcote about doing this via DCC some time ago, but as I’m building a new layout, I haven’t yet got round to considering how I’m going to deploy these same uncouplers. 
in DC mode, there are adjustment controls on the circuit board to fine tune (a) the height and fall of the ramp and (b) the duration of the rise. I’ve found them to work well, and will be considering how to use DCC on this build.

Might be worth calling Heathcote as I’ve found them helpful.

I’ll be interested to see what evolves on this thread.

Ian

PS. I too will be using Roco Z21 and iTrain on new layout.

Edited October 30, 2023 by ITG
Added PS

[deepfat]

Thx @ITG

Looking at the Heathcote site it says DCC uncoupler available soon. I need a few of these so I was thinking one board to control multiple servos like we do with point motors as I will have several of these near each other like my station and sidings.

 

 

[ITG]

Ah yes, i recall now I think he said something similar to me…. Albeit a few months back!

I guess there are two ways of doing this.

The height/duration adjustments needed could still be done on the supplied board, and then one would need a simple on/off trigger via a DCC command/decoder.

or, maybe the whole control board could be replaced by DCC commands.

For the former, I think decoders similar to those suitable for solenoid point motors which deliver a quick ‘switch’ might be ok, as if the rise and duration are preset by the ‘DC’ board, the incoming ‘switch effect’ would be all that was needed.

Please post any progress you make as I’d find it helpful

Ian

[Nigelcliffe]

I think there's a risk of over-complication from what's written above.

 

 

To move a servo requires a servo control board.   If wanting to operate this from a DCC command, then it makes sense to have the DCC Accessory Decoder and Servo movement in one device.   There are many of those available on sale.   

 

The command then comes from the DCC system (effectively a command from within iTrain) to operate the accessory device.  

 

Or, given the movement is very simple, a slow-action turnout motor could make the mechanical movement, and that could be controlled by a suitable accessory decoder.   

 

 

[deepfat]

OK I can see the sort of thing now Zimo MX821s will control 8 servos so two of these and I am done I think

[34theletterbetweenB&D]

2 hours ago, deepfat said:

...the Kadee doesn't look right for era 3/4...

That has to be qualified as location dependent. The knuckle coupler was in extensive service during 'era 2', and its use expanded significantly thereafter.

[Stephen Freeman]

13 minutes ago, deepfat said:

OK I can see the sort of thing now Zimo MX821s will control 8 servos so two of these and I am done I think

Hardest part will be finding one to buy, probably easier to buy a Megapoints servo control board and his DCC add on board. Maybe more expensive but I can't find anyone in the UK who has MX821s

[deepfat]

I think my good friends at YouChoos have the Zimo units  As for knuckles/buckeyes I am modelling SR between the two wars, but not a deep expert on couplings so happy to be corrected. However from the photos I have and the films I have watched of this era I don't see them in evidence in the quiet corner of Sussex where my layout is set. Of course what I have now is not prototypical either but if I was going to move to system I'd want it to look more like it should for the money

Edited October 30, 2023 by deepfat

[Nigelcliffe]

2 hours ago, Stephen Freeman said:

Hardest part will be finding one to buy, probably easier to buy a Megapoints servo control board and his DCC add on board. Maybe more expensive but I can't find anyone in the UK who has MX821s

 

Youchoos list the Zimo MX821S  as in stock at about £66  (controls eight servo motors)

 

Alternatively, Coastal DCC list an ESU Switchpilot servo for a little over £50.  

 

 

(Megapoints gets very expensive for DCC control of devices,  requiring both a Servo board (£36 for four servos, £66 for twelve)  and a DCC interface for that board (£34).   The "system 2" items are more expensive.  
 

[Stephen Freeman]

42 minutes ago, Nigelcliffe said:

 

Youchoos list the Zimo MX821S  as in stock at about £66  (controls eight servo motors)

 

Alternatively, Coastal DCC list an ESU Switchpilot servo for a little over £50.  

 

 

(Megapoints gets very expensive for DCC control of devices,  requiring both a Servo board (£36 for four servos, £66 for twelve)  and a DCC interface for that board (£34).   The "system 2" items are more expensive.  
 

I looked at all 4 websites and failed to find them.

[34theletterbetweenB&D]

1 hour ago, deepfat said:

As for knuckles/buckeyes I am modelling SR between the two wars

Take a look. https://sremg.org.uk/coach/maunsell.shtml

[Tim123]

7 hours ago, Stephen Freeman said:

I looked at all 4 websites and failed to find them.

https://www.youchoos.co.uk/Index-Shop.php?CAT=Decoders

 

scroll right to the very end of the page, MX821S is 3rd from last.

[ColinK]

Intetesting discussion.  One of my friends is building a HO and HOm layout, so 16.5mm and 12mm gauges with ‘european’ couplings. We’ve been struggling to find a way of making uncouplers when this thread popped up.  Latest suggestion was square brass tube through the baseboard, slightly smaller square brass tube through it, uncoupling plate (brass, plastic or 3D printed) on top, servo under the baseboard to push the ramp up.  But we’ve no kniwledge nor experience of using servos.  Happy to be DC or DCC operated.

[ITG]

On 30/10/2023 at 22:50, ColinK said:

Intetesting discussion.  One of my friends is building a HO and HOm layout, so 16.5mm and 12mm gauges with ‘european’ couplings. We’ve been struggling to find a way of making uncouplers when this thread popped up.  Latest suggestion was square brass tube through the baseboard, slightly smaller square brass tube through it, uncoupling plate (brass, plastic or 3D printed) on top, servo under the baseboard to push the ramp up.  But we’ve no kniwledge nor experience of using servos.  Happy to be DC or DCC operated.

The idea of square section tubes is a good one. On the Heathcote product as supplied, it needs two side-by-side (at 90 degrees to track) thin steel piano wire rods to keep the rising uncoupler platform parallel to the tracks. On some of mine, I modified that to use two plastic tubing rods in a straight line parallel to the track. Same reason.

But maybe a single square section rod within another would not be able to twist as the servo raises the platform. I may have a closer look at this when I get round to re-installing these uncouplers on the new layout build.

Any thoughts on suppliers for the square section rods?

Ian

[Nigelcliffe]

7 minutes ago, ITG said:

The idea of square section tubes is a good one. ........

Any thoughts on suppliers for the square section rods?

 

Numerous suppliers of such - any shop with a "Albion Alloys" or "K&S metals" rack is likely to have something.  And there is also plastic from "Plastruct"  (again a rack in shops which stock it).    A flatter rectangle section may be better, arranged as a slot along the line of the track.  

If wanting a neat install, square/rectangle tube inside a round tube, the round fits into round baseboard hole.

 

However, a single lifting small round rod may be all that's required, with a secondary rod parallel going into a generous diameter tube to stop rotation of the ramp.  The second rod needs the generous tube or things are bound to catch/jam.    That could be achieved with an operating rod which is bent over at the top to resemble a staple.     That may be quicker/easier to make and install.   

 

- Nigel

 

[ColinK]

Many thanks, the Gaugemaster electric tension lock uncoupler has the actuating rod and a second rod in an attempt to keep it straight, but its not long enough so the whitemetal uncoupling plate usually turns and shorts out the track.  It uses a solenoid which is very noisy.

 

The idea of me using a rectangular rod is great, should work better. It might be possible to 3D print a combined rod and uncoupling plate.  I just happened to have some square brass tubes that fit inside each other that I’ve used for removable signals on another layout.

 

I know very little about servos, especially how to set the limits of movement.  Perhaps someone like Megapoints might have an appropriate servo controller?

[idd15]

This is how I implemented prototype ramps on my layout. They are cut down lolly sticks with a small screw into plastic tube. The tube slides in another tube glued through the baseboard. A panel pin is pushed through the ramp at one end and goes through another hole in the baseboard to stop rotation of the ramp.

 

The ramp connects to the servo arm with a very thin wire to give some flex.

 

Bit crude, but does work provided ramp goes up parallel. It is also fiddly to set up. Servo is driven by Megapoints controller which allows you to control servo direction and throw, again this can be a bit fiddly.

 

I've not got around to refining this as I found the number of button presses on the dcc controller to address a point or uncoupler "got in the way”. If you have a dcc mimic diagram on a tablet then this would not matter.

 

I will probably go back to toggle switches driving the Megapoints controller directly.

HTH

Idd

 

[deepfat]

Thanks for this @idd15  I will experiment on the same lines  with a central screw and guide posts at either end.  However other fish to fry just now as my Rapido Dan's House keeps de-railing

[young37215]

I did something similar using servos and Megapoints a while back which is close to being perfect but not quite. The system works but the plasticard top is not long enough which means that you have to be very precise in where the train stops. With the benefit of 12 months experience, I will be swapping the plasticard top (the piece that sits on top of the the track) for the top piece of a Peco uncoupler. I have a number of these sat spare and hope that the increase in length will make it easier stop a train on top of the uncoupler. The servo element works very well, I have no plans to change this element of the uncoupler.

 

 

[ColinK]

Many thanks idd15 and young37215, your posts are really helpful snd very much appreciated.

[ITG]

The example given by @idd15 is very similar to how I did with my modified approach from the Heathcote product on the now dismantled layout. I found I did need two rising rods to ensure no twisting.

I’m hoping if I use a square tube fitting inside a slightly bigger square tube, that I then may be able to only use a single hole through the baseboard.

As @ColinK says, I also tried the Gaugemaster solenoid type but I too found there was slight twisting.

Ian

[Nigelcliffe]

Comments on Idd's photo of the servo linkage.   What's shown works, but possibly unnecessarily complex...    If the uncoupler plate and rod is heavy enough to fall under gravity, then all that's needed is the end of the rod to rest on the servo arm and be pushed up.    No linkages to bend up and fit!

 

Megapoints servo controllers are fine.  There are cheaper ways with numerous published DIY designs (some extremely simple), or there are kits from MERG. 

  

 

 

[idd15]

2 hours ago, Nigelcliffe said:

Comments on Idd's photo of the servo linkage.   What's shown works, but possibly unnecessarily complex...    If the uncoupler plate and rod is heavy enough to fall under gravity, then all that's needed is the end of the rod to rest on the servo arm and be pushed up.    No linkages to bend up and fit!

 

Megapoints servo controllers are fine.  There are cheaper ways with numerous published DIY designs (some extremely simple), or there are kits from MERG. 

  

 

 

Yes absolutely this would be another way of doing it and I did consider it. You could make a suitable cam by mounting two servo discs face to face with the centres offset by the required rise which, is only about 1mm I think. 

 

However, in my particular case because the layout is supposed to be portable I didn't want the ramps falling out when carried and stored on end! Though this problem could be overcome by using a thin countersunk head bolt through the baseboard as the anti swivel pin with a nyloc nut on it. In fact adding a few nuts would give the ramp a bit more weight as well! 

 

The other reason for using the wire linkage was to ensure that when the ramp was retracted it was positively locked down and less likely to cause a derailment. Perhaps a bit of overkill but "murphy's law" always applies I have found...🙃

 

cheers

idd

[JimFin]

I opted for the simplistic approach - works fine with ESU ServoPilots running the servo's. Brass tube through the baseboard to act as a sleeve and fine rod with a plate to lift the coupling. Shown fitted to HOm track.