Casting AC&Y 3900 Series 50' SS Box Car

[wazzou]

We have already been through this with Bryan, no another thread. 

I don't know if that is "in" or "on"?  I'm sure it's not supposed to be no.

Most people can recognize trolling Peteski.  You don't need the aid of the       

[SAH]

Hmmmm.  I guess there really is no such thing as an innocent question when it comes to resin casting. 

I figured you guys would recommend a one piece casting.  All reasons given are sound of course.  I'll need to get some practice in before I tackle that approach I think. 

The longer working time resins may be what I need to investigate.  I don't plan to become a production caster.  I'm just looking for a way to produce a few copies for personal use without scratching/bashing every one.  Sinking cash into equipment I'm not sure I'll use again doesn't make sense to me.  If I get hooked by the casting bug, then I'll certainly consider it.

One more question  - In the Resin Casting thread it was noted that harvesting 1st generation castings for future masters was important.  The implication was that the original master is destroyed in the mold making process - except when the master is metal.  Is this true for all masters made from non-metallic material?

Chris - These were leased cars circa 1959 to 1970 on the AC&Y.  The DD were ex -MP leased from Purdy.  The 10' SD were ex- SLSF leased from AA Morrison.

Thanks for all the tips, recommendations and sources.  You guys have a wealth of knowledge and I appreciate your sharing it.

Steve

[DKS]

One more question  - In the Resin Casting thread it was noted that harvesting 1st generation castings for future masters was important.  The implication was that the original master is destroyed in the mold making process - except when the master is metal.  Is this true for all masters made from non-metallic material?

No. The material used for the master has little or no bearing on whether or not it survives. For instance, my crawler is made of acrylic pieces glued together, plus some wire details. I've made a couple dozen molds from the master, and it's still in perfect shape. I also have other masters made of wood, plastic and combinations of several materials that are still fine even after making numerous molds. It's difficult to know in advance if a master will survive, although you'll start to get a sense of a master's survival potential after you've made a number of molds. What dictates survival is a combination of how delicate it is and whether or not it has a lot of undercuts, although that's an oversimplification. In some cases you'll know for a fact that a master has no chance of surviving, in which case you'd stockpile a bunch of first-gen castings.

[Chris333]

BTW I'm still waiting for my RI boxcar from Rocket Express. I asked him if he got my check after a while and he said he did and had to re-mold the boxcar before he could make me one. Guess his old mold wore out.

[SAH]

Thanks for the clarification David and for sharing your knowledge.

I wonder how many N scale RI boxcars he sold Chris.  Better yet, how many of those were built.

[Sokramiketes]

I caught him at RPM-Naperville and bought a kit.  It's built and painted, waiting for decals.  I should snap a photo as it's a nice casting.

[SAH]

Throwing caution to the wind, I've been experimenting with one piece casting.  I decided to use the old Con-Cor 1-1/2 door 50' single sheathed box car as a test bed.  It's similar to my target AC&Y model and the casting isn't as fine as the Walthers source model I'll be using, which is probably an advantage in that if I can cast the CC model I should be able to do the other.

Here are the first "successful" (using the term loosely) castings and the master.  These pieces are from the second try at a mold.



Here is the mold and master.



I've learned a LOT so far.  Thanks to all you guys for the helpful hints.  The learning curve would have been much steeper without your advice.


Steve

[OldEastRR]

Any threads here before that explain this whole process? Like what pressure pots are for, etc?

[SAH]

This is the thread that got me to start thinking seriously about resin casting.

https://www.therailwire.net/forum/index.php?topic=28614.msg311704#msg311704

Great information but I've noticed that resin casting threads often break down into something akin to a holy war (of words).  Sift through though and there are nuggets of gold to be found. 

Also search "pressure pots for resin casting" on the web.  YouTube videos and other helpful topics.  I've not purchased one yet. 

As for step-by-step instructions, some one with more experience might point you in the right direction.  I just jumped in with what I've learned here. 

Steve

[wazzou]

This is the thread that got me to start thinking seriously about resin casting.

https://www.therailwire.net/forum/index.php?topic=28614.msg311704#msg311704

Great information but I've noticed that resin casting threads often break down into something akin to a holy war (of words). 

Steve

Generally, only when someone may ask a similar question or explain their own experiences, perhaps, in more than one thread on the topic.   

[peteski]

Generally, only when someone may ask a similar question or explain their own experiences, perhaps, in more than one thread on the topic.   

[daniel_leavitt2000]

I think Dave, James Will and I are all on the same page. We use similar Smooth-On products and we have all experienced success with pressure casting both mold and resin.

I have had no real problems with my Harbor Freight paint pot. I know what Dave was referring to on the clamps: they do take a while to tighten and loosen which can cause problems if you are working with multiple pots. Since I only use one for personal casting this is no real issue. To prepare the pot for pressure casting, I simply removed the siphon pipe on the lid (it obstructs the interior and is easily unscrewed from the lid). I also added a blade valve to the paint-out line to bleed air after casting. Lastly, I removed the gage and bypass valve from the air-in line.

A Home Depot cheapie 3 gallon air compressor will work, but not ideal. It takes about 3 minutes to pressure the pot up to 65PSI, my preferred casting pressure.

On deterioration of the master: it takes a lot of planning to make sure the master survives the casting process. I recently built a FGE boxcar for casting, though I have not yet made molds (still waiting on the basement for that). I decided to remove all interior bracing for several reasons: 1. flat sides are easier to build up. 2. An interior without supports allows you to mount the completed shell to a solid block. This will allow you to avoid filling the shell with clay. Removing clay has been a MAJOR problem with masters for me.


Top: Mater
Middle: Casting platform (will be filled with clay when casting)
Bottom: Interior of master


Master mounted on casting platform.


Master interior slides right into master after the outside of the mold has been cast.

[Sokramiketes]

Are you worried about the pressure pot collapsing the hollow shell?  If so, just add a couple bleed holes to the bottom of your mold box, within the outline of the shell, to allow pressure to equalize on both sides.  This requires a good seal around the perimeter of the shell to the mold box floor, but you'd do that anyway I presume.

[peteski]

Are you worried about the pressure pot collapsing the hollow shell?  If so, just add a couple bleed holes to the bottom of your mold box, within the outline of the shell, to allow pressure to equalize on both sides.  This requires a good seal around the perimeter of the shell to the mold box floor, but you'd do that anyway I presume.

That sounds like deja-vou all over again.  I seem to recall Daniel, in an earlier thread casting ,showing a similar photo and DKS making a similar statement.

[wazzou]

That sounds like deja-vou all over again.  I seem to recall Daniel, in an earlier thread casting ,showing a similar photo and DKS making a similar statement.