NZT School Bus and Caterpillar kits en route to dealers

[tom mann]

Oh man I wish I would have picked these up.   

[DKS]

Oh man I wish I would have picked these up.   

LOTS more on the way! All five of my pots have been humming all afternoon. Lost count how many I've cast. In a few days you'll be able to order what you want from at least two sources.

[peteski]

Karin,
I will be, but mine are going to be cargo on a Pennsy F41 flat so they won't be weathered much.

http://railroadmanuals.tpub.com/TM-55-2200-001-12/css/TM-55-2200-001-12_279.htm

Hmmm... those wood cradles could be ... very easily laser cut, out of wood!

Hint, hint, for a possible add-on product for Stonebridge: a pack of 5 Cats plus the cradles as a flat car load.

[Alaska Railroader]

Hmmm... those wood cradles could be ... very easily laser cut, out of wood!
Hint, hint, for a possible add-on product for Stonebridge: a pack of 5 Cats plus the cradles as a flat car load.

Ha! And you are a mind reader! Actually i was looking at the profile in the diagram and thought about lasering the chocks, or more properly named cradles I see, but wasn't going to jump out there unless asked. Like David my schedule is pretty tight but those are pretty small and easy enough to do.....

[daniel_leavitt2000]

Are there more vehicles planned? I would love to see a backhoe.

[DKS]

We are planning to do more vehicles. Nothing yet has been planned as to what they may be, however.

[peteski]

Ha! And you are a mind reader! Actually i was looking at the profile in the diagram and thought about lasering the chocks, or more properly named cradles I see, but wasn't going to jump out there unless asked. Like David my schedule is pretty tight but those are pretty small and easy enough to do.....

Nice!  It sounds like you just made Bryan's (and probably several other's)  modeling much easier! I'm glad that I expressed my thoughts.

[bbussey]

Ha! And you are a mind reader! Actually i was looking at the profile in the diagram and thought about lasering the chocks, or more properly named cradles I see, but wasn't going to jump out there unless asked. Like David my schedule is pretty tight but those are pretty small and easy enough to do.....

Nice!  It sounds like you just made Bryan's (and probably several other's)  modeling much easier! I'm glad that I expressed my thoughts.

Karin, since you offered ...

Works for me!  I'll buy a set whenever they are done.  Then I can load up my flat that already has a wood deck.  I can weather it appropriately now that I know what's going on it.

[seusscaboose]

We are planning to do more vehicles. Nothing yet has been planned as to what they may be, however.

regardinfg the Caterpillar line... i would suggest adding at least one of the "mini" excavator products...   this would open you up to Modern modelers.

EP

p.s. of course, the vintage products can still be seen today in various forms and functions, as noted in the beginning of this thread.

[Philip H]

I plan to get a coupel of these Cats and rig as pipe draggers for oil field work.  Still fairly common.

[pnolan48]

David,

Could you give us some idea of your production cycle? I see you've got five pots. How many castings in each pot, and for how long under pressure? Or is that being too nosey? I'm casting these huge parts--like 20 oz. a pour--so I don't have any idea of what might be entailed with such tiny stuff. I'm doing my masters out of digitally-cut styrene of .020 or .030 thickness, and also, incidentally, leaving holes for .010 wire (for rigging).

[chicken45]

Works for me!  I'll buy a set whenever they are done.  Then I can load up my flat that already has a wood deck.  I can weather it appropriately now that I know what's going on it.

F41? Who makes that?

[bbussey]

Athearn makes the casting.  This one has been modified with body-mounts, end sills and grab irons.  The deco is custom and the deck is a laser-cut addition.

[DKS]

David,

Could you give us some idea of your production cycle? I see you've got five pots. How many castings in each pot, and for how long under pressure? Or is that being too nosey? I'm casting these huge parts--like 20 oz. a pour--so I don't have any idea of what might be entailed with such tiny stuff. I'm doing my masters out of digitally-cut styrene of .020 or .030 thickness, and also, incidentally, leaving holes for .010 wire (for rigging).

Production cycle, castings per pot, time under pressure, etc. are all extremely variable. Castings per pot can be anywhere from 1 to 100 or more, and is more dependent on the work time of the resin than pot capacity; work time dictates how many molds can be filled, and by what means. Time under pressure depends on the resin used, from 30 minutes to 2.5 hours or more. Test molds take 5 hours, production molds 12-24 hours. Pots are 12" diameter by 10" deep, so you can figure from that what they can hold.

I make no secret about how I work. The main difference for me from most others doing casting is I use very high pressure, 75-85 psi. Many casting veterans will claim that's not necessary, but the proof is in the results. I've tried lower pressures, and they do not yield the same results. I do not do any mold material or resin vacuum prep (this makes some people's head explode). I also use no mold release on anything but the mold parts of two-part molds (another one that flies in the face of convention--mostly because you can often see mold release, or its effect, on finished product). Aside from careful cleaning, the only master prep I do is to seal those made from certain porous materials such as wood and RP.

Mold yield is also variable depending on the size, shape, details, undercuts, etc. A typical one-part mold for me may yield 100 castings (I have some very simple molds that have well exceeded this), while some will die after a dozen. Success also varies, although I have very few molds that deliver less than 99% success; the crawler molds so far have delivered 100% success after pulling 60-80 pieces.

The goal of some shops often is to reduce cycle time; mine, by contrast, is to increase quality.

[pnolan48]

Thanks, David!

As always, I appreciate your work, and willingness to share your methods.

I've been using vacuum prep for molds only to remove moisture, as air bubbles haven't been much of a problem in my huge molds. The vacuum prep also extends the life of the mold raw materials, much like a blast of nitrogen. I've found the gallon buckets are pretty hard to fill with nitrogen and get the lid down before it all escapes.

I can't cast under pressure as I would need too large a pressure pot and one huge compressor to achieve any pressure before the resin sets. In large volumes, ten-minute resin sets in less than three minutes.