Author Topic: Stupid Idea #2,100,432  (Read 1095 times)

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kelticsylk

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Stupid Idea #2,100,432
« on: January 01, 2013, 11:57:33 PM »
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Considering I now have quite a few Trix steam locomotives with oversized flanges I was thinking of a way to cut them down. I have done the file on the driver with the engine running and it works as long as you take it slow and light. Too much pressure and the wheels will come right off the axles.

One thing I don't like about cutting them down is the fact that you end up with "smaller" wheels spaced too far apart. I started to wonder...Is there a way to build up the tire so the flange is smaller? I was thinking of nickel silver tube or something that could be slid unto the driver and glued in place...

Just a thought.

I know someone is going to suggest I just throw the mech away and just replace it with thus and such. Not gonna happen, exceeds the budget.

nkalanaga

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Re: Stupid Idea #2,100,432
« Reply #1 on: January 02, 2013, 12:14:09 AM »
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Except for the flange being part of the tire instead of the wheel, that's exactly how most steam drivers were made.  If you're a good machinist, or know one, it wouldn't be that hard.  Trix wheels are easy to remove and replace, so I'd start by turning the existing wheel flat, if it's tapered.  Then turn a tire from tubing of the correct outside diameter, thinning the inside on a lathe, until it's a press fit.  Cut the resulting thinned tube to width and you have your tire.  If you want a tapered tread, start with a tube slightly oversize and turn both sides.  You could start with one the correct inside diameter, that would probably be hard to find.

The hardest part will be keeping it in place.  Solder would be best, but would probably melt the wheel center.  Glue would work fine, but would also insulate the tire.  The prototypical method might work.  Heat the tire, and for a model, chill the wheel.  Put the tire on the wheel, and when it cools, it should shrink into place, making a tight fit.  That would require VERY precise machining.  Another option would be to drill holes through the tire and wheel, after gluing, and insert press-fit pins.  Turn the pins smooth with the tire and they'd both conduct electricity and reinforce the joint.
N Kalanaga
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DKS

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Re: Stupid Idea #2,100,432
« Reply #2 on: January 02, 2013, 06:13:47 AM »
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Glue would work fine, but would also insulate the tire.

Might not. Depends on the fit. If it's fairly snug, some areas of the new tire will still make sufficient contact with the original wheel, even with glue (I've not enlarged wheels this way, but I have made metal cylinders out of telescoping tubing segments glued together, and they still conducted). It's worth a try at least.
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Lemosteam

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Re: Stupid Idea #2,100,432
« Reply #3 on: January 02, 2013, 06:28:15 AM »
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Hmmm interesting.  May not need glue or solder at all. 

As Nick mentions the prototype heated the tire to expand it, pounded it onto the wheel until it was seated and let it cool, shrinking to a press fit.  This could work the same on the Minitrix driver which are all metal, except for the insulator on one side which can be remove and reinstalled.  A drill press would suffice for the press and a microtorch for the heat source.  Drop it on, press it down let it cool.  It will never come off.  It may even cool to the same taper as the wheel wheich is very slight.  What wall thicknesses are we looking at?

The toughest part may be cutting the tubing into a ring, which could also be done on a drill press...

Hmmmm.  Me likie.

DKS

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Re: Stupid Idea #2,100,432
« Reply #4 on: January 02, 2013, 06:45:37 AM »
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My bigger concern would be material. I'd prefer not using brass, so is tubing close to the required size readily available in NS?

Edit: Looks like this might be a good staring point: http://www.metalsmith.co.uk/metals-materials.htm
« Last Edit: January 02, 2013, 06:53:26 AM by David K. Smith »
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victor miranda

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Re: Stupid Idea #2,100,432
« Reply #5 on: January 02, 2013, 11:02:28 AM »
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wall thickness on k+s tubing is about .016 as I recall.
so If you can find a tube the right size,
you should be able to reduce the flange and make the tire bigger.

lemosteam's comment about heating the new 'tire' can work.
and I am pretty sure that loc-tite will also hold.

for a while, the folks at NWSL sold nickle-silver round stock.
I have never seen N-S tubing for sale....

so the N-S tire is a machining option.

the only problem I see is that red loc-tite
might interfere with electrical pick-up,
so if you pick that option you will want improved tender pick-ups.

not a bad idea at all. 
It may not be easy to do...
exact brass tube and driver sizes being the only real question.

mmagliaro

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Re: Stupid Idea #2,100,432
« Reply #6 on: January 02, 2013, 11:40:26 AM »
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This is really a new way of looking at this problem! 
I'm going to rummage and see if any tubing I have is even close to fitting
over, say, a K4's tire.   I don't think conductivity will be a problem.  No matter what kind of
glue you use, I'd be amazed if you could press a brass ring over the wheel and not have it
be making contact somewhere.

There are other issues, however. 

1. You will lose any traction-tire groove on the wheels that have them.

2. The wheel is going to look a little weird.  The spokes in the wheel center will not extend
all the way out; you'll have this odd-looking super-thick rim on the wheel.   That might be a worthwhile
compromise to make in exchange for bigger drivers, close wheel spacing, and small flanges.

DKS

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Re: Stupid Idea #2,100,432
« Reply #7 on: January 02, 2013, 12:37:30 PM »
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I have never seen N-S tubing for sale...

http://www.metalsmith.co.uk/metals-materials.htm

I've found several other sources as well, but it's not sold online; you have to order it by phone. Getting the exact size might be difficult and/or costly. Turning solid rod stock is viable, but probably tedious and time-consuming to hog out that much metal.
« Last Edit: January 02, 2013, 12:40:36 PM by David K. Smith »
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u18b

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Re: Stupid Idea #2,100,432
« Reply #8 on: January 02, 2013, 12:51:23 PM »
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I guess I don't understand the original problem.

When you turn down the wheels,  you ONLY work on the flanges- correct?
If so, then the Trix tires are the same.

Or are you saying that while the tires are the same, the APPEARANCE is different since you can now see more daylight between the wheels with the flanges turned down.
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TiVoPrince

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Re: Stupid Idea #2,100,432
« Reply #9 on: January 02, 2013, 01:38:09 PM »
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Crumstances 
where you could overlay boxpok, scullin or other wheel faces would certainly disguise an overthick tyre if you applied a new tread surface.  But, without incredible machining how would you get the wheel to flange and other contours correct?  Not that I want to rain on your parade...
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Lemosteam

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Re: Stupid Idea #2,100,432
« Reply #10 on: January 02, 2013, 02:37:32 PM »
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i Victor, David's link has some viable diamters in NS.  May need to turn down the wheel to fit the tubing ID better though...

This is only to increase the tread diameter closer to proto, so as to NOT have to grind the flanges.  Grinding the flanges creates a larger space between the wheels making the wheelbase appear incorrect (even though it is). 

BTW, This would also raise the chassis by the wall thickness of the tubing.

Hornwrecker

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Re: Stupid Idea #2,100,432
« Reply #11 on: January 02, 2013, 08:37:51 PM »
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I do know someone who has a company that draws tubing for brass instrument makers, and he does do them in NS.  I don't know what the largest tube wall thickness he can do is, or how small a lot for an oddball size?  Thicker wall size probably requires hydraulic drawing

When I need a small amount of a weird size tubing for a repair, I make it out of sheet stock and braze it together (Ag brazing), and then pound the hell out of the seam on a mandrel, then file or turn on my lathe, then burnish it.  Not too difficult to do, but takes some practice.

I really ought to get around to building  that draw bench that I've been putting off, then I'll be able to draw to size, especially tapered tubing.  Don't know if it will do offset tapers, like for N scale boilers.  Have to talk to a few other horn makers to see what the possibilities of drawing tubing down are.
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Re: Stupid Idea #2,100,432
« Reply #12 on: January 02, 2013, 10:22:13 PM »
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I'm also not too keen about the extra-thick tire.  That IMO is going to look even weirder than too much daylight between drivers with turned down flanges.
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