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weighting locos with tungsten putty -- flow & viscosity problems

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  • Member since
    July 2017
  • From: Delaware
  • 65 posts
weighting locos with tungsten putty -- flow & viscosity problems
Posted by SpringStreet on Monday, August 14, 2017 3:09 PM

I'm using some tungsten putty to weight and balance a couple of steam engines (and some other things around the house). But I find that the material will flow with surprising ease, oozing its way out of place. (Room temperature is a steady 70 to 72F, so it's not due to excess heat.) Are there differences in viscosity among different brands of tungsten putty (I'm using Pinespeed brand)? And does anyone have any tips for keeping it from flowing (in locations that don't easily lend themselves to solid weights)? Is it enough to, for example, cover it with thin tape? Thanks much for any tips.

  • Member since
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Posted by Anonymous on Monday, August 14, 2017 5:14 PM

There seem to be different viscosities. Here is a relatively stiff on:
https://www.youtube.com/watch?v=zhIuP5SeksY

You could make your own putty from tungsten powder and epoxi resin. Here is a discussion: https://arstechnica.com/civis/viewtopic.php?f=11&t=1194165

I'll try to use tungsten rods of different sizes to reduce air space and glue them in place.
Regards, Volker

  • Member since
    September 2003
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Posted by mlehman on Tuesday, August 15, 2017 12:43 PM

I use Pinecar, which is Woodland Scenics' pinewood derby line of goodies. Never had that problem. The stuff will dry out if you let air get to it, so you might try that for a day or so with yours, then cover it for a day again, then see what it's like. Sounds like it might be a bad batch, just too much solvent (whatever it is?) or perhaps some folks do mix it more towards flowable.

At the room temps you cited, it shouldn't do that IMO. Pays to remember that your motors will generate heat, which if the problem only occurs in close proximity to the motor, could be the issue?

Mike Lehman

Urbana, IL

  • Member since
    April 2003
  • From: Clinton, MO, US
  • 4,261 posts
Posted by Medina1128 on Thursday, August 17, 2017 1:24 PM

If your putty is too viscous, try putting it in the fridge for a few minutes before using it. 

  • Member since
    May 2004
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Posted by 7j43k on Thursday, August 17, 2017 2:47 PM

density of polystyrene:   1 gm/cm

density of Zamak:   6.8 gm/cm

density of brass:   8.3 gm/cm

density of Cerrobend:   9.1 gm/cm

density of tungsten putty:  10 gm/cm

density of lead:    11.34 gm/cm

density of depleted uranium:  19.1 gm/cm

density of tungsten:   19.25 gm/cm

 

Zamak is the stuff they cast "underframes" from.  And other things.

 

Ed

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