Does Anybody Make a "Working" N Scale Switchstand?

[C855B]

For Jason @wcfn100 , photos of a Pettibone-Mulliken "Star" switchstand including a handy ruler are here: http://www.everywherewest.com/switchstand/

General close-up:



A fun surprise while I was outside taking the switchstand pics:

[wcfn100]

Thx, Mike.  I'll see what I can do.  I've got a sheet of .1mm and .2mm started with random stuff so that will be the first decision.

Jason

[ncbqguy]

Back in the early 1970s I helped a friend install switchstand turnout throws on Shinohara code 70 turnouts.
They were scaled down "Slanzer" (the NMRA author) throws made from music wire and K&S brass tubing.  The plans came from an NMRA "Bulletin" from the same decade.
The throw had a 270 degree rotation with sprung pressure to the points and also provided selected electrical power to the points/frog.
The parts were mass prefabricated and could be mounted to a block to ease installation.   The handle above the layout could be made near scale and targets/lantern added for appearance.
Charlie Vlk

[peteski]

Back in the early 1970s I helped a friend install switchstand turnout throws on Shinohara code 70 turnouts.
They were scaled down "Slanzer" (the NMRA author) throws made from music wire and K&S brass tubing.  The plans came from an NMRA "Bulletin" from the same decade.
The throw had a 270 degree rotation with sprung pressure to the points and also provided selected electrical power to the points/frog.
The parts were mass prefabricated and could be mounted to a block to ease installation.   The handle above the layout could be made near scale and targets/lantern added for appearance.
Charlie Vlk

In N scale!?  Or was it H0?

[ncbqguy]

The article was for HO, the layout was N. We scaled down the parts for N.   The advent of Kadee Micro-Trains trucks and cars uncovered that all the then-current Peco turnouts were tight gauge over the points necessitating replacement of all 50 or so on the railroad.   We did the conversion over a two week period IIRC.   
Bruce Turner, the owner, was a dispatcher on the BN.   We had a round-robin club called the Bolingbrook Branchliners.   I was transferred out of the area and he moved on to the Black Hills and elsewhere for his career.  Last I heard he was retired in the St Louis area and wasn't in good health.
Charlie Vlk

[Lemosteam]

I think you're going to run into issues with Shapeways' FXD minimums, if that's your benchmark. A variation of this idea of this may work better in etched metal. The solid rack-and-pinion is good work and would result in something durable. But Lennart is right, the biggest challenge is 90° end stops and spring connection between the throwbar and post for the overtravel to flex for the stops.

It stopped raining, so I need to get my butt out of the house and over to the studio to take those pictures.

Nope. That's already designed to SW minimums. The radii in the tip of each tooth is R0.2mm, although I have not sent it for an official SW pass.

Ask yourself if you really are worried about the target face being perfectly perpendicular to the track.  In reality my design is adjustable, the rack can slide on the throwbar until you have it where you want it. Or as I mentioned, the targets could be glued in place after install. Then as Long as you alive 90 degrees of radial travel the other target face shot in turn be perpendicular. If you gear it properly, there's should be no need for stops. You just need 90 degrees of axial rotation for 2.?mm of lateral movement in the points. That is the biggest obstacle for a geared design. But in reality you have already achieved that with a lever. The etched gear is a good idea too.

What you see is merely conceptual and actually is quite small.

[narrowminded]

Nope. That's already designed to SW minimums. The radii in the tip of each tooth is R0.2mm, although I have not sent it for an official SW pass.

Ask yourself if you really are worried about the target face being perfectly perpendicular to the track.  In reality my design is adjustable, the rack can slide on the throwbar until you have it where you want it. Or as I mentioned, the targets could be glued in place after install. Then as Long as you alive 90 degrees of radial travel the other target face shot in turn be perpendicular. If you gear it properly, there's should be no need for stops. You just need 90 degrees of axial rotation for 2.?mm of lateral movement in the points. That is the biggest obstacle for a geared design. But in reality you have already achieved that with a lever. The etched gear is a good idea too.

What you see is merely conceptual and actually is quite small.

I don't know if folks realize how small this needs to be to be functional with a .040" switch travel, and possibly less.  The theory doesn't need to consider size but actually making one does.  

With no play in the linkage or gear lash the pinion gear will have to have a .051" (1.295 mm) pitch line.  An 8 tooth .2 mod pinion gear (as small as it gets hoping for availability and already stretching the minimum tooth limit) is already at 1.6 mm.  That's 19% error meaning it shows in travel at that amount and then add any lash in the gears directly to that.  If you can get a .15 mod 8 tooth gear (and the rack) you may be able to do it but that's TINY and I'm not aware of any ready source for such a thing.  But those are the numbers.

Mike, do you have a picture of your servo setup?  If you could get just a little more throw (it doesn't have to be 90 degrees, just action convertible to linear motion more than .040") to work with the thing becomes exponentially easier to accomplish and with a simple lever as described earlier.

[narrowminded]

Here's a conversion I did a few years ago for one of my brothers.  (This isn't the first time i've thought about this.)  

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I wasn't modelling at the time but did a few of these for his use.  It's a code 80 turnout and what this is is an operating switch stand but for use as a manual operator for a standard Atlas twin coil that was flipped over and mounted under the switch and sat in a 1/4" deep pocket in the benchwork.  That made for a clean installation but lost the manual operation, hence the design as demonstrated.  It was indication but also manual overide. 

One of the reasons to show it was that it actually reached and was driven by (as well as driving, in manual) the inverted manual button on the Atlas machine.  Those machines have a fixed travel of 1/4" so the travel was sufficient to make a lever that worked reliably and the motion was repeatable so the crank arm could be accurately made ahead of time with the precision needed for all parts to function properly.  It worked really well and the throw was quite accurate.

[C855B]

... Mike, do you have a picture of your servo setup?  If you could get just a little more throw ...

As you can see, not easily attainable:

[BCR 570]

I played around with this for a while.  As others have mentioned, the challenge is the very short throw and the very short crank dimension, both of which will be individual to each turnout to some degree.

Briggs Models offers a Racor 31B switch stand kit with resin base and etched staff and target.  It is designed to be operable if desired, but does not come with any mechanism.

My main concern with these is susceptibility to damage.


Tim

[narrowminded]

I see.  I actually like that assembly for powering, though. 

If you laid it out I'll bet you could come up with a small pivot on the adjacent fixed tie, driven by the throw bar, with a decent length pigtail extending away from that pivot to the stand to amplify the motion that the stand sees.  That could be bent at the pivot to change the direction (90 degrees back maybe?) and keep it aimed in the desired direction of the stand's mounting window.  The 90 quadrant in the stand could be oriented to whatever position the amplifying spring arm wound up in.  If it was from small, maybe .010" or less music wire, it could have a little bit of over travel built in to handle variations from different turnout travels while driving the stand into a fixed stop.  The flex in the spring wire would assure accurate full travel and accommodate errors that might do damage.  This method might lend itself to some Shapeways parts, too.

One way might be to engage the throw bar from underneath, over to the bottom side of the adjacent tie, up through a drilled hole, and then bent down in the direction of your stand with a long whisker that ultimately drives the stand at some distance away and therefore plenty of travel.  Lay it out and see if that might not be a viable approach. Another option you have with these ties is they are solvent weldable so you might even be able to make your pivot assembly from ABS or styrene on the bench as a sub assembly and then position it to the tie and solvent weld it in place.  No flaky glue or CA joints.

There's gotta' be a way!

[mmagliaro]

I used to get my SS hypo-tubing from Small Parts Inc. They had a *HUGE* selection of those and lots of other useful items. But several years ago they got absorbed into Amazon and it is a format shadow it itself (and last time I tried to shop on their website was not fun).  N-gineering has some of that tubing too, but you can always Google "stainless steel hypodermic tubing" for some additional sources.

In addition, there is Albion. 
http://www.mmodelstore.com/albionalloys.aspx

Not stainless, but nickel silver is still pretty darn durable, and a big advantage is that you can solder to it.

I have been using the Albion brass micro tubes on my 0-6-0.  The stuff is wonderful.

Smallest size is 0.3mm OD, 0.1mm ID.  That would be a tube only .012" OD, with a bore of about .0039".  Yikes.

Of course, they have larger sizes in 0.1mm increments.   Something between 0.5mm and 1mm (3 - 6" in N Scale) ought to work well.

[Lemosteam]

I see.  I actually like that assembly for powering, though. 

If you laid it out I'll bet you could come up with a small pivot on the adjacent fixed tie, driven by the throw bar, with a decent length pigtail extending away from that pivot to the stand to amplify the motion that the stand sees.  That could be bent at the pivot to change the direction (90 degrees back maybe?) and keep it aimed in the desired direction of the stand's mounting window.  The 90 quadrant in the stand could be oriented to whatever position the amplifying spring arm wound up in.  If it was from small, maybe .010" or less music wire, it could have a little bit of over travel built in to handle variations from different turnout travels while driving the stand into a fixed stop.  The flex in the spring wire would assure accurate full travel and accommodate errors that might do damage.  This method might lend itself to some Shapeways parts, too.

One way might be to engage the throw bar from underneath, over to the bottom side of the adjacent tie, up through a drilled hole, and then bent down in the direction of your stand with a long whisker that ultimately drives the stand at some distance away and therefore plenty of travel.  Lay it out and see if that might not be a viable approach. Another option you have with these ties is they are solvent weldable so you might even be able to make your pivot assembly from ABS or styrene on the bench as a sub assembly and then position it to the tie and solvent weld it in place.  No flaky glue or CA joints.

There's gotta' be a way!

Yes there is- leverage.

The image below is to scale  mates to the Atlas turnout dimensions, will print in FUD and my motion file says it will move and deliver 90 degrees of travel over +/- 0.6mm of (my) measured travel of the throwbar.  The lever will be trapped by the stand when as the final part of assembly.\ and the targets aligned as the last step.  the tuber diameter is 0.8mm.

[bbussey]

This is an NJ International switch stand connected to a peco switch, so that the switch stand would rotate when you threw the switch (by pushing the rails with a finger - the switch stand wasn't strong enough to actually throw the switch). I had to drill an extra hole in the rod on the switch stand  to make it the right length so that it would rotate 90 degrees in response to the peco throw distance. The layout doesn't exist anymore, so I can't go back and retake the picture so that the switch stand is in focus.

This is what I plan on doing.  I have the NJI switch stands on hand, and they will pivot when connected to the turnout throwbar.

[wcfn100]

I still need to lay it out, but this is the design I'm going for using .2mm.



Not sure if it will even work, but I'll throw it on my next .2mm sheet I have etched.

Jason