MTB MP1 point motor query

[spikey]

For use with 00 gauge Peco Streamline points, am I correct in assuming that I would use the default 6mm travel and that I need to remove the point spring?

 

Also, is the supplied pin/wire OK to use, or am I better off using something with a bit more give/spring in it in order to avoid the risk of the mechanism being strained at each end of travel?

[Butler Henderson]

As with any slow motion motor yes the overcentre spring needs to be removed; the mechanism has an auto power off at the end of travel so I would have thought the only issue would be the point not throwing as far as it should if the supplied wire is insufficent. I had an issue with a Tortoise working a signal that hardly moved the semaphore with the supplied wire and had to substitute a thicker wire.

[SamThomas]

Are you mounting the MTB underboard or surface ?

[spikey]

2 hours ago, SamThomas said:

Are you mounting the MTB underboard or surface ?

 

Under

[SamThomas]

You need something with a bit of give/spring & the Peco overcentre spring removed.

 

Something like the piano wire type rod they sell in radio control shops for control surfaces. 0.5mm could be a starting point but I would get a selection.

I would think the default 6mm will be about right - you just want the rod to keep the point blades in place without undue strain.

 

I've been using these motors for a while & find them excellent, underated & much smaller than Tortoise or Cobalts.

[spikey]

35 minutes ago, SamThomas said:

You need something with a bit of give/spring & the Peco overcentre spring removed ...

 

Much obliged Sam.  I thought so ...

 

Right.  Now to try and find online supplier of thin piano wire in small quantities ...

ETA - Supplier found no problem.  Now all I have to do is work out how I'm going to remove sections of the baseboard cross-members that are exactly where two of these new motors need to go in order to replace the surface-mounted solenoids!

 

 

Edited December 26, 2021 by spikey
update

[RobinofLoxley]

I havnt had to use anything other than the provided pins. When setting the PM's up, sometimes there was an audible noise. This could be stopped by releasing the two screws and allowing the drive to settle in the right place then tightening again. I had to do that with a few of the motors. Depending on the starting position of the pin, it may be necessary to move the point with those screws loose to get everything in the right place. Once done, its finished.  I havnt removed any springs from the points although it may be best practice. My control is z21 - Digikeijs DR4018's.

[SamThomas]

Regarding the cross members that are in the way could you not mount the motors on the suface & hide them ?

 

Another alternative when surface mounting is to use radio control bell cranks which can turn the movement 90 degrees.

[KingEdwardII]

10 hours ago, spikey said:

am I correct in assuming that I would use the default 6mm travel

No, you should switch to use 3mm travel, which reflects the actual movement of the tie bar on Peco pointwork. Doing this is straightforward - watchmakers screwdrivers to open/close the motor body and a pair of tweezers to modify the location of the plastic pin (see MP1 instruction leaflet).

 

10 hours ago, spikey said:

I need to remove the point spring?

That is entirely up to you. MTB MP1s can drive Peco points with the spring left in. However, you may prefer the smoother movement that you get if you remove the spring. The MP1s will ensure that the tie bar is kept firmly at the end of the motion, so the spring is not needed for that.

 

10 hours ago, spikey said:

is the supplied pin/wire OK to use,

Yes, most certainly. I would not advise you to change the wire to something with more give in it - that might mean that the tie bar is not kept in place properly. The rigidity of the supplied wire is a definite advantage - the mechanism in the motor is designed to lock the wire in place at the end of travel. The rigid wire ensures that the tie bar cannot move from its end position.

 

10 hours ago, spikey said:

avoid the risk of the mechanism being strained at each end of travel?

You minimise straining the mechanism by using 3mm travel.

 

 

I've now installed over 30 MTB MP1 motors underboard driving Peco pointwork and I use everything as supplied by MTB, with the only change being to switch to 3mm throw. All works perfectly.

 

Yours,  Mike.

 

PS:

5 hours ago, spikey said:

work out how I'm going to remove sections of the baseboard cross-members

When I had the problem of a point tie bar located directly over a baseboard cross member, I cut out a section of the cross member using a Coping Saw, large enough to accommodate the MP1 in the correct location. I reinforced the cross member with some material that was out of the way of the MP1.

[Harlequin]

I used 3mm throw and the pins as supplied. I removed the springs from the Code 75 turnouts.

The motors are fixed to the baseboard directly under the turnouts: 9mm ply plus 3mm cork.

In one place I had to offset the motor to avoid a support and I simply bent the pin into a crank shape and carried on as before.

Everything works fine so far.

 

Edited December 27, 2021 by Harlequin

[spikey]

Thanks folks.  All good stuff.

 

Ref baseboard cross-members and the removal thereof, they're under a three-way which currently has surface-mounted SEEPs but mounting the MTBs above board is out for a couple of reasons.  The woodwork modification's feasible, it's just that the doing of it's going to be a PITA on account of the need the shift quite a lot of wiring out the way beforehand.  It would also be easier if I had a tenon saw, but perseverance, the end of a handsaw, the Dremel and a hammer and chisel will no doubt do the trick ...    

[RobinofLoxley]

I spent hours at the planning stage to avoid motors over baseboard joins. It wasn't possible to avoid laying points across them as they are every 60cm something few modeller's have to contend with. Bad luck if you have to hack the woodwork about. 

 

I left all my pms at 6mm. The idea of these motors is that they drive up to a resistance then stop. As long as they are stopped by the end of the tie bar travel and not by the mechanism it doesn't matter how much unused travel exists. You would have to be very accurate with positioning to use 3mm successfully I feel.

[PaulRhB]

I changed to 0.8mm piano wire in the smaller clamp on the motors to give a little less pressure after pulling the blade out of an older point tiebar!

I use the 3mm throw too on 009 and OO and I fix them in place with double sided foam tape underneath to reduce noise a bit and use 2mm o/d servo screws through the lugs for security. 
 

Just for info I made up this from their instructions and it also indicates which switch contact applies to which position. 
Basic image copyright Mp1 point motors. 
 

[Izzy]

34 minutes ago, spikey said:

Thanks folks.  All good stuff.

 

Ref baseboard cross-members and the removal thereof, they're under a three-way which currently has surface-mounted SEEPs but mounting the MTBs above board is out for a couple of reasons.  The woodwork modification's feasible, it's just that the doing of it's going to be a PITA on account of the need the shift quite a lot of wiring out the way beforehand.  It would also be easier if I had a tenon saw, but perseverance, the end of a handsaw, the Dremel and a hammer and chisel will no doubt do the trick ...    

 

I don’t know how much of the pin would stick up above the baseboard surface but could you mount them underneath offset where there is space and then drive the tiebar via a length of wire/rod from the pin?

18 minutes ago, RobinofLoxley said:

I left all my pms at 6mm. The idea of these motors is that they drive up to a resistance then stop. As long as they are stopped by the end of the tie bar travel and not by the mechanism it doesn't matter how much unused travel exists. You would have to be very accurate with positioning to use 3mm successfully I feel.

Are these stall motor type? With their adjustable throw I’d always assumed they were fixed distance travel. Be handy to know for future reference as I may well switch to them sometime. Thanks.

[SamThomas]

I found the 3mm travel fine when first using these motors. However, both the point & motor needed to be mounted spot on & I felt that problems could occur with a portable layout due to transport vibration & variations of temperature humidity so I found the 6mm travel with "give" in the rod a better option for me - others will have different experiences.

 

As with most slow action point motors dropping the voltage will quieten them down.

 

[Harlequin]

36 minutes ago, RobinofLoxley said:

I left all my pms at 6mm. The idea of these motors is that they drive up to a resistance then stop. As long as they are stopped by the end of the tie bar travel and not by the mechanism it doesn't matter how much unused travel exists. You would have to be very accurate with positioning to use 3mm successfully I feel.

 

11 minutes ago, Izzy said:

Are these stall motor type? With their adjustable throw I’d always assumed they were fixed distance travel. Be handy to know for future reference as I may well switch to them sometime. Thanks.

 

No, they are not stall motors and they won't stop pushing when they meet resistance!

 

If you are not controlling them by a timer, which some electronic solutions do, they must be allowed to reach the end of their travel.

 

Edited December 27, 2021 by Harlequin

[Izzy]

9 minutes ago, Harlequin said:

 

 

No, they are not stall motors and they won't stop pushing when they meet resistance!

 

If you are not controlling them by a timer, which some electronic solutions do, they must be allowed to reach the end of their travel.

 

Many thanks. That’s what I thought but then began to wonder.

[KingEdwardII]

48 minutes ago, RobinofLoxley said:

You would have to be very accurate with positioning to use 3mm successfully I feel.

Not at all, in my experience. It's pretty simple to get the right position for the motor.

 

However, one of the beauties of the MP1 is that is has fine adjustment available and you can easily move the position of the wire both sideways (relative to the tie bar) and also along the direction of the track.

 

28 minutes ago, Izzy said:

Are these stall motor type? With their adjustable throw I’d always assumed they were fixed distance travel.

No, the MP1s work on the basis of a fixed distance of throw, related to the rotation of the motor through 180 degrees. The motor only turns off once the rotation is complete - if this is prevented for some reason (e.g. foreign body on track stops the tie bar from moving) then the motor stays active and you get a distinct hum that alerts you to a problem.

 

Yours, Mike.

[RobinofLoxley]

My mistake! So mine are working fine on the basis that the pin bends enough at the end of the travel past the point where the tie bar stops. I suppose thats about 1.5mm at each end.

On 27/12/2021 at 08:26, Izzy said:

Are these stall motor type? With their adjustable throw I’d always assumed they were fixed distance travel. Be handy to know for future reference as I may well switch to them sometime. Thanks.

Interestingly based on the same text in the instructions, I assumed that because of the 3mm steps between adjustment points that beyond those points the motor simply stops under resistance. Also the lack of any comment in the instructions, about the possibility of motor burnout etc.

[PaulRhB]

13 minutes ago, RobinofLoxley said:

Also the lack of any comment in the instructions, about the possibility of motor burnout etc.

The second paragraph of the instructions says,

”The mechanism has a end of travel detection switch, i.e. the control voltage can be applied permanently, to be disconnected automatically once a respective position is reached and the motion stops.”

 

That would cover them if you burn out the motor by stalling it  

[Butler Henderson]

The motor travel as with a Colbalt or  Tortoise surely should not be affected as the wire rod will counter any stuck point mechanism.

[Izzy]

51 minutes ago, RobinofLoxley said:

My mistake! So mine are working fine on the basis that the pin bends enough at the end of the travel past the point where the tie bar stops. I suppose thats about 1.5mm at each end.

Interestingly based on the same text in the instructions, I assumed that because of the 3mm steps between adjustment points that beyond those points the motor simply stops under resistance. Also the lack of any comment in the instructions, about the possibility of motor burnout etc.

Reading that the applied voltage can be varied, 9-12vDC or 12-15vAC, I would guess that as well as being a bit slower/quieter at the lower voltages they might also be slightly less powerful and less likely to burn out through overload if prevented from reaching their end travel. Same as RC servos. But this non-stall design is what makes them, like servos, much more powerful, and better IMHO, than the stall types. The much smaller footprint is another big bonus. 
 

Apart from the different wiring connections, additional 12mm throw option, and extra switches to the MP-1, I can can’t quite work out what the differences are between the MP-5/ MP-6/ MP-7. Looking at the overall basic size I assume (dangerous I know), that they all share the same motor and gearing system. 
 

I really must get a few to experiment with. 

[KingEdwardII]

1 hour ago, RobinofLoxley said:

I assumed that because of the 3mm steps between adjustment points that beyond those points the motor simply stops under resistance.

If you open the mechanism, it becomes clear how the MP1 works. It is easy to open the package with some jewellers screwdrivers - and you actually need to do this if you want to change the throw distance.

 

Inside there is a neat assembly that converts the rotary motion of the motor into a linear motion that moves the metal pin. The assembly has a small plastic pin which can be positioned at one of 3 different radii on the circular component attached to the motor - and it is these radii that dictate how far the linear slider moves between the endpoints (ie. 3/6/9 mm). A neat and simple design. Once the end point is reached, the linear slider is basically fixed in place by the positioning of the plastic pin, so that the metal pin driving the tie bar is unmovable and keeps the tie bar in place.

 

The motor rotates the circular component through 180 degrees and there are switches that detect each end of travel and cut the power to the motor once the end point is reached. So if the end point is not reached, the current is still applied to the motor - e.g. if something jams the turnout. You get a buzzing sound if this occurs. I don't know if the motor would burn out eventually if the current is left on, but I do know that the motors don't burn out quickly - I've had some left on for up to 10 seconds or so when there was a problem. They take a fairly low current, so would probably take quite some time to overheat.

 

Yours,  Mike.

 

PS The plastic pin that needs repositioning to change the throw distance is very small - I advise that when you reposition it, you do this in some container that can catch it if you drop it. It's not a good plan to have to hunt for that pin on the floor!

Edited December 28, 2021 by KingEdwardII

[KingEdwardII]

10 minutes ago, Izzy said:

I can can’t quite work out what the differences are between the MP-5/ MP-6/ MP-7.

The MP5 motor is equivalent to the basic MP1, but with 2 built-in microswitches rather than one. The MP1 single switch is fine for handling polarity switching for an electrofrog turnout. However, there are some configurations involving e.g. diamond crossings where you may need to control the power applied to both rails - MP5 will do that.

MP5 also has a 12mm throw option, but at the cost of the package being larger.

 

MP6 is like the MP5 but provides pulse control to initiate the movement - e.g. pushbutton activation. MP7 is a variation of the MP6 where the pulse polarity changes for the 2 endpoints. MP1 & MP5 are oriented towards switch operation (or the equivalent via an accessory decoder like the Digikeijs DR4018).

 

MP1 is smaller than MP5/MP6/MP7 - it's only 28mm x 40mm.

 

Yours,  Mike.

 

 

[PaulRhB]

14 minutes ago, Izzy said:

But this non-stall design is what makes them, like servos, much more powerful, and better IMHO, than the stall types.
 

I’ve used Tortoise and the Cobalt derivative design on scales from N to G and there’s plenty of power in a stall motor so I don’t see that as an advantage really. The design is slightly easier to adjust in situ as you just move the slider so there are no screws to come loose or risk over-tightening. The Tortoise is also very reliable long term and the only failures on mine or a friends layout were a cracked case on one about 25 years old. It was strapped up and a plate welded on with plasticweld and continues to give good service. 
If the MP1 proves to be that robust long term it will be very impressive. 

 

14 minutes ago, Izzy said:

The much smaller footprint is another big bonus. 

This is the main advantage to me although I do like the inbuilt decoder on the Cobalt offering rather than having to connect separate decoders in and there’s always either not enough to fully justify a multi switch decoder or one too many!

 

To me they are pretty much equal, if I’ve got the depth the Cobalt/ Tortoise is slightly easier to set up, if the space is restricted on one or more then the Mp1 is the logical solution.