77 replies to this topic

[private_lego]

dlp4341, on 10 August 2010 - 03:21 AM, said:

I got a HS 55 servo, but it came without instructions or a wiring diagram. I can not get it to operate with just 6 VDC. Any hints?
Don

To operate a servo motor you need a microcontroller or servo controller unit.
It works with pulses to get to the required position.
HS-55
How does servo's work

[aprendiendo]

dlp4341
peterab

Thanks,I tried several "Pure Lego" solutions, but this was, by far, the easiest one.

[skaako]

Hi there... if you are not too concerned about using a pure Lego solution, you could try this idea. Using the old tray motors from CDROM drives i have managed to fit them inside 2 hollowed out 2 x 4 bricks, as you can see in the photo... plus a few more photos here My link



The reasons i prefer these motors is the size and cost.. which has been at no cost for me, just the time needed to pull the motors from old drives. And also the motor has enough force to change the switch, but not enough to rip the motor from its mounting.

I did have to reduce the friction in the switch... but by just squeezing the friction piece (inside the switch) together with a pair of pliers.

Mike

Edited by skaako, 16 July 2011 - 01:01 PM.
Oversized image removed

[JopieK]

I like my solution also:




The only modification is hot glue (that can be peeled off again). A servo drives the points.

[skaako]

Wow.. thats cool. Thats the first cable operated switch i have seen on here. I wonder if anybody has tried a rod or linkage controlled switch?

[dlp4341]

Jopiek

Very clever.

If the train runs backwards through a closed switch is there enough give in the cable to  avoid a derail ?
Looking at the last photo, that would be traveling right to left against the closed sliding section of rail.

Keep up the good work

Don

[JopieK]

dlp4341, on 29 October 2010 - 02:50 PM, said:

Jopiek

Very clever.

If the train runs backwards through a closed switch is there enough give in the cable to  avoid a derail ?
Looking at the last photo, that would be traveling right to left against the closed sliding section of rail.

Keep up the good work

Don

Well, there is, I use servos to get this. I have succesfully uses this system at LEGOWorld 2010 without any derails...



@skaako: thanks for the compliment, more info can be found here: PF to the limit

[NoWheels]

in the video you posted, how did you control the speed of the train?  very nice work

Edited by NoWheels, 12 July 2011 - 02:42 PM.

[Rob Klingberg]

I've been tinkering around with this problem (electrifying switches) for several months myself, as it really seems like the holy grail of Lego train operation.  I've taken the approach that *not* modifying switches (removing friction) is more important than using 100% Lego parts, but I'd be curious to hear what others thought.  What are the most important factors in a switch motor, in your opinion (in order of importance):

*  All Lego parts
*  No switch modification needed
*  Small size (or ability to mount underneath a table)
*  Uses standard 9V Lego battery pack (or similar Lego power source)

I've also made the assumption that using RCX/NXT elements is cost or supply prohibitive for large layouts (10+ turnouts)-- would others agree?

--Rob

Edited by Rob Klingberg, 13 July 2011 - 02:41 PM.

[deejay]

Hi all,

i have this solution. it function very good. The Motors are clipped on the Tracks.
The Tracks must modified a little bit. (Cut the Plastic on the top and in the bottom)

Edited by deejay, 13 July 2011 - 07:50 PM.

[Toastie]

dejay,

he was asking a couple of questions ...

Quote

What are the most important factors in a switch motor, in your opinion (in order of importance):

*  All Lego parts
*  No switch modification needed
*  Small size (or ability to mount underneath a table)
*  Uses standard 9V Lego battery pack (or similar Lego power source)

I've also made the assumption that using RCX/NXT elements is cost or supply prohibitive for large layouts (10+ turnouts)-- would others agree?

Hi Rob,

for me it would be

#1: NOT modifying the switch
#2: Using standard LEGO "power" (regardless of battery (9V), rechargeable (7.something), LEGO AC wall warts ("10" V AC), LEGO DC wall warts (10 V DC) or power from a PBrick (NXT/RCX/Scout) - which just translates to bridge rectifier, matching capacitor, voltage regulator and that's it. But this way you can use virtually all LEGO power systems. If you'd run on low voltage drives (3 V) you could include 4.5 V battery boxes as well (... my maniac building across multiple themes idea).  
#3: Small size but preferentially with all LEGO parts
#4: All LEGO parts

and then: You can cut down the costs NXT/RCX wise considerably when you multiplex the outputs of the PBricks. Which means you need third party electronics ... the benefit though is very smart operation of the switches; the NXT/RCX could do some additional calculations just for fun when idling ...

Regards,
Thorsten

[aprendiendo]

This was the best solution I found, 100% Lego, no Lego part modified, small size (I think it could be still smaller):



I used the old RCX motors, but you can use any Lego motor [Edited: or non Lego motor, no servo needed].

You can view how it works in this video:

Edited by aprendiendo, 14 July 2011 - 05:39 PM.

[Toastie]

Quote

This the best solution I found, 100% Lego, no Lego part modified, small size (I think it could be still smaller):

Hi aprendiendo,

wow, I remember seeing this, and I guess I asked you about the control (I found the NXT and the control super exciting) but I completely missed that you have built your mechanism in a way to easily push the point blades against the soft spring loaded mechanism. And 100% LEGO. This is brilliant!!!

I guess I need to get this going ...

Regards,
Thorsten

[skaako]

Hi Rob,

I think for me the order would be..

#1 Price: I know price wasn't originally in the list but for me was the main factor in my solution. If i get around to motorizing all of my switches i would require over 30 motors. Using all Lego components seemed a bit on the expensive side.

#2 Small Size (& aesthetics): With my modified switches (shortened, 3 way, etc.) i could have yards where the tracks are very close, therefore i needed something really small, and using non-Lego motors meant i had more choice to choose something compact. But also i wanted something that looked really good alongside the track too, i was fortunate enough to find the motors i used could be encased in 2 2x4 bricks.

#3 No Switch Modification: For me the important factor was not modifying any of topside switching mechanism, this means the switch can be used again with the original lever without any visible signs of modification. As for removing friction no parts have to be cut off, the friction piece just needs squeezing together (Although the bottom cover has to be opened). I couldn't find a small motor with greater torque, it would have been nice to be able to add to a switch that has had no modifications whatsoever.

#4 Using All Lego Parts: It would be nice if Lego remade something similar to the 9V Micromotor but i don't really see that happening. I did build a switching unit with this type of motor, but i only have 3 so using them for all my switches wasn't and option to consider. Plus these motor have a few drawbacks. Also to add a Lego cover for the motor would have resulted in a unit 4 studs wide, which was larger than i what i needed.

#5 Using a Lego Power Source: This was always the least important factor for me because i know i will want it to be controlled by something custom built in the end. Although throughout the building and testing i always use a Lego 9V regulator with a polarity switch.


As for using RCX/NXT for the control of the switch motors. I have not considered them myself as i build my own controllers, and i work it out as price per switch. The units i have built myself are daisy-chainable (up to 128 devices, but easily expandable) and control 4 switches each for a cost of about $10NZ in parts. Thats only $2.50 per switch. Whereas using an NXT ($140NZ lowest price i have ever seen) with a total of 4 outputs standard would be $35 per switch. You could buy a 3rd party multiplexer to increase the number of outputs, but then i don't think it would be considered an all Lego solution. Another option that i have used for controlling switches and other MOC's is the older Lego CLI interface. I managed to pick it up for $90 a few years ago and with 8 outputs that's only $12.50 per switch.

Thanks for reading. This is a topic i really enjoy :)

Mike

[Rob Klingberg]

Thanks Toastie and skaako for your input!  All great points.  The multiplexing idea is a very good one (and necessary for economies of scale on large layouts), and one I have also looked at.  I have also been using servos instead of motors because of their ability to ensure accurate positioning (with a motor, it is difficult to make sure it has fully thrown the switch without the addition of two pressure sensor switches or some other, more complex mechanism).  Servos are so cheap these days, and as others have said, can be easily controlled with microcontrollers.

I'm curious: how many people have layouts with space beneath the switch to hide a large servo?  This would be similar to the Tortise switch machines used elsewhere in model railroading.  I don't have a permanent layout myself, so my experiments have needed to use a very large assembly mounted directly next to the switch.  Just curious if under-the-switch mounting is a workable option for most people with large layouts.

Thanks again for the input!

--Rob

Edited by Rob Klingberg, 14 July 2011 - 04:30 PM.

[aprendiendo]

Rob Klingberg, on 14 July 2011 - 04:29 PM, said:

...
I have also been using servos instead of motors because of their ability to ensure accurate positioning (with a motor, it is difficult to make sure it has fully thrown the switch without the addition of two pressure sensor switches or some other, more complex mechanism).  
...

If you use a rubber belt as transmission mechanism you can use a simple motor (Lego or non Lego). You can see an example with a simple old Lego RCX motor, no servo, in my previous post. You don't need accurate positioning, you only need to give the motor some more time running than necesary, the rubber belt will slip a little but it's not a problem.

Edited by aprendiendo, 14 July 2011 - 05:38 PM.

[eric87]

deejay, on 13 July 2011 - 07:34 PM, said:

Hi all,

i have this solution. it function very good. The Motors are clipped on the Tracks.
The Tracks must modified a little bit. (Cut the Plastic on the top and in the bottom)

Can we get a parts list on this solution??
Just the non Lego parts.  I would like to try and make a few of these.

[skaako]

Rob Klingberg, on 14 July 2011 - 04:29 PM, said:

..I have also been using servos instead of motors because of their ability to ensure accurate positioning (with a motor, it is difficult to make sure it has fully thrown the switch without the addition of two pressure sensor switches or some other, more complex mechanism).  Servos are so cheap these days, and as others have said, can be easily controlled with microcontrollers..

Hi Rob, i agree with aprendiendo, servo's do give more accurate positioning but is not really required in this case. The motors i selected have more than enough torque to throw the switch (reduced friction) but not enough to cause damage when the end of the throw is reached. I control these motor with a microcontroller through a low power motor IC. I could reduce the timing down to 20ms and would still throw the switch, however i kept it to 50ms just to be certain, and would give a nice click when the switch is changed.

eric87, on 14 July 2011 - 06:14 PM, said:

Can we get a parts list on this solution??
Just the non Lego parts.  I would like to try and make a few of these.

If you want to try building something similar to mine Brickshelf Gallery, i just use the small motors that can be found in old CD or DVDROM drives, not all of them have this motor but most do, and the good thing is that the motors always seem to be the same for different brands. I use 2 hollowed out 2 x 4 bricks to house the motors, but can be housed any way up to you. The friction does need to be reduced in the switch for the motor to work effectively, but no modifications need to be made to the topside of the switch like in deejay's solution.

[HenrikLego]

This seems to me to be a really good solution! I would love to find out where I could find a load of these small engines. What are those Lego-parts you use there?

I am an absolute "electric newbie" but this seems like something even I can pull of! :)

[Rob Klingberg]

Thanks skaako, one question on the motors you have used: are they strong enough to throw switches that have not been modified (i.e., have had their friction reduced)?  If so I would be very interested in more info on those specific motors.  In my testing I have not been able to throw a non-modified switch without using a servo.

Thanks!

--Rob

[skaako]

Hi Rob,

Thanks for the interest, but i did have to reduce the friction in the switches to get them to work with this type of motor.
I experimented too with about 10 different types of DC motors that were available to me at the time. Even with a much larger motor it still didn't have enough starting torque to throw an unmodified switch. It would really require a motor with internal reduction gearing, but all the motors i could find were much larger than what i wanted. I would have liked to have found something small that could do this, but without reducing friction in the switch it takes quite a bit of force to throw the switch. And it seems like the newer RC Switches have more friction than the 9V ones. Even when switching by hand it feels too much sometimes, my little nephew agrees too :)

Thanks again

Mike

[I am Lego]

Hi there Mike,
  I have been along time watcher of this forum, but didn't join until today, and only because i wanted to ask you a few questions.
   I brought a few old cd-rom drives to extract the motors from, but unfortunatly they were some what different from the one's you used. I did track down some from Anaheim Automation.com . In particular the BDD-20-25 series motor ( i haven't brought any yet) . These appear to be the closest in dimensions to what you describe. They are 25mm long in the body and 20.4 by 15.4 wide and have a shaft that is 10mm long( is this close to what you use???) My other question is how did you attach the lego lever to the motor shaft so that it wouldn't spin freely?
  Look forward to your reply,  Shane.

P.S. and in response to all the purists who think that a "non" lego solution is a crime, since when do lego actually make the motors themselves?? They may well mold plastic but as for making the actual motors , well it would be fair to say that a third party "non"lego company is reponsable for that !!

[skaako]

Hi Shane,

I'm sorry to hear you didn't find any of the motors in the drives that you had. The first time i used these motors i had 20 old drives from my brothers work and i managed to get 14 motors from them. The next time I got given 10 from a friend and i only found 4 that had the right type of motor. I found that the older CD only drives seemed to have these motors, but i have found one in a DVD writer too. It's best if you can get broken old drives for free from computer repair shops etc. The motors are from the part that moves the laser assembly back and forth, it takes a bit of disassembling to get them out. The motors you have found are larger than the ones from the CDROM drives, i don't have one handy to measure but they were 12mm wide and about 29mm in length as they could fit snugly into a 2x4 brick, and about 15mm high so they can fit into 2 bricks high. I couldn't believe how well they fit inside the bricks, the top 2x4 brick fits on tightly without the need for gluing or fastening in any way.

As for attaching the lever, i drilled a 0.8mm hole into the piece and push fitted it onto the shaft, the motor doesn't have enough torque to slip inside the piece. For the first few i made i had to use a little superglue as i drilled the holes too big.

As for being purist or not is up to personal preference, i'm not sure how many varying degrees of purism or non-purism there is. I guess there are some that use only official bricks produced by Lego, some that use bricks made by 3rd parties such as BBB wheels or Brickarms, some that use any sort of bricks available, some that modify bricks, some use non-Lego items for scenery, etc etc and the list goes on. Some of the most impressive MOC's i have seen have included slightly modified bricks and non-Lego scenery.

I think for competitions etc, the use of only official Lego components is fair, but for me i find it more fun to combine non-Lego hobbies.

Thanks for the interest, i hope you have some better luck with getting the motors :)

[I am Lego]

Hi Mike,
I tracked down a different motor, a 6v with a body of 12x12 and 20 mm long. The shaft is 13mm long, the only thing i am unsure about is the shaft diameter ( the web page has conflicting info as to whether it is 1mm or 2mm). I am assuming that if you used a .8mm hole in the lego throw switch , that your shaft is 1mm ( especially as it would seem that 2mm is the same diameter as the pins on the throw switch).
        Cheers, Shane.

[skaako]

Hi Shane, that's good if you can get them at a reasonable price. I was having a look today, but i couldn't find any local suppliers. I found a supplier site to give a bit more details of the motors here. And also another interesting page i found here that makes good use of this type of motor.

As for the shaft it was about 1mm. I think the same for the motor you're looking at, 2mm sounds too large for this size motor.

Let me know how you get on with finding something suitable :)

Mike