MOC: Class 158 DMU with PF Doors

[Andy Glascott]

Hi everyone,

I've been working on this for several months, and although not perfect, it's time to go public in the hope of some advice!

The shell of the Class 158 was relatively easy to build, but I wanted more than that in a 6 wide MOC, so inspired by others (Esbin Kolind on EB and Carl Greatrix on Flickr, EB etc) and their work on doors, both powered and not, I decided to have a go at powering (some of) the doors.

The challenges were several - space and the fact that each door is in effect two working as a pair, and so needed power delivered to each half. The mechanism works smoothly when powered by hand, but now that I've added an M motor to power it, it is a bit sticky opening the doors. I haven't yet taken stills or video of the mechanism, I'm just pleased enough to have got this far at the moment! (Link to video below.)

The issues (and my thoughts on causes):

1 - it's a bit slow as a train! I'm using an old RC motor I was given 2 Christmases ago, I suspect I need to replace the O rings for better traction. (It's also very heavy!). Switch to a newer PF train motor?

2 - The doors stick. I know that the design involves sliding doors into a tight space and have managed to get a system that pushes them out parallel to the walls of the unit and then slides them along, then reverses the procedure to close, just as on the real thing. I think the M motor is a little weak in the power (torque?) it has, do any of you with more electrical/engineering know-how have anything to suggest? For example I have an old 9v technic motor I could swap in, it currently powers the lift in my station. I doubt I could get an L sized PF one in the space I have.

The video of the doors -

- shows that the concept works, excuse the ape-like arm assisting occasionally!

Any suggestions will be gratefully read and tried out!

Thanks in advance,

Andy

PS If anyone knows how to embed the video, please feel free to or point me towards the tutorial. Thanks.

Edit: video embedded. Thanks AussieJimbo

Edited January 24, 2012 by Andy Glascott

[AussieJimbo]

The DMU looks great, Andy.

Nice start on the doors, seems very promising.

To embed the video use the "insert media" button - - at the top of the post editor.

:classic:

Edited January 24, 2012 by AussieJimbo

[Tearloch]

For starters, I absolutely love your layout.

I have not tried powered doors yet, but do you think clearance is an issue? It looks like the doors fit pretty snuggly inside the chassis, and my first thought is that it is a clearance issue. With the square edges on both the doors and the chassis, it may bind up slightly as they try to pivot out (assuming it is a basic "4 bar" type of mechanism). You may try applying some lithium grease to the inside edge of the doors and the frame (it may be messy, but it would answer the question). You could also consider using some sand paper to slightly round the edges of the door frame to overcome this (if that is the issue).

The other possible cause that comes to mind is that the two doors may be binding in the center as they both try and open at the same time. You could think about doing is setting up the drive linkages so that one door opens first, then the second door opens. This may require removing teeth from a gear to set up the timing circuit (allow them to run on one motor).

[kyphur]

I would think about adding a connection points to the top edge of the doors. That should smooth out the motion and reduce binding as the doors move in/out of the opening.

[Dan-147]

2 - The doors stick. I know that the design involves sliding doors into a tight space and have managed to get a system that pushes them out parallel to the walls of the unit and then slides them along, then reverses the procedure to close, just as on the real thing. I think the M motor is a little weak in the power (torque?) it has, do any of you with more electrical/engineering know-how have anything to suggest? For example I have an old 9v technic motor I could swap in, it currently powers the lift in my station. I doubt I could get an L sized PF one in the space I have.

As far as getting more torque from the motor, you could try gearing it down. Speed and torque have an inverse relationship (The faster it turns, the less torque it has). If the action (doors opening) is slowed down, it might actually allow the different parts to "fall into place" more easily. Hope this helps.

Dan-147