Finally, forward progress on steam part casting

[daniel_leavitt2000]

A few members lent me parts to cast last year, and boy has it been a challenge.

After nearly a half-dozen failed attempts, I have a set of molds that are giving acceptable results.

I'm not sure why this project had such a high failure rate, but I suspect that the volume of parts being cast and my relative inexperience with multi-part casting may have been the culprit.

Unlike my previous casting project, the FGE 5145, I chose to dye the resins in the containers for more consistent results. I used two squirts of black urethane dye in the part B of Smooth-On 321.

Because steam is run in much smaller and infrequent batches, these parts will be kept on hand to modify whatever comes our way to be more prototypical of B&M engines.

Photos taken at work on my cell phone and bad, bad lighting. Forgive me.


Domes fresh off the sprue. I still need to work on that smoke box front.


More domes and parts for medium sized engines.


This was the big challenge. There is just no good way to cast steam cabs. Too many undercuts and openings. The photo shows them a little more rough than they actually are; the filed black plastic turns to light gray. Also brightness was boosted to comical levels to shoot this. Minor imperfection on the roof, but manageable.


MDC tender shell casting.


Bachmann ALCO 2-6-0 tender shell. There are a few minor imperfections in this that I'll need to address. These are a direct replacement for the slope-back tender chassis. Great for switchers!


MP Mogul/American tender shell. Need to work on these a bit.


An experiment. This was a Riv skinny tender shortened and the bunker heavily modified.

[peteski]

Those castings look pretty damn good!  Will they be available for sale?
Are you still residing in New England or have you moved to the faraway Asian lands?

[u18b]

I agree with Pete.... those castings look great.

For the rivet detail to show up so well..... did you use a pressure pot?

[daniel_leavitt2000]

Pete, I still need to get the MP tender shell back to you. Let me know what you would like and throw them in the box.

Pressure pot set to 65 PSI.

If anyone needs anything specific, let me know.

Still living in the US, but I won't be able to send anything out till I get back from vacation in early October. Joy and I are going on a bit of a road trip though the Netherlands, Belgium, Luxembourg and if we have time, into Germany for a pint or two.

[peteski]

Pete, I still need to get the MP tender shell back to you. Let me know what you would like and throw them in the box.

Pressure pot set to 65 PSI.

If anyone needs anything specific, let me know.

Still living in the US, but I won't be able to send anything out till I get back from vacation in early October. Joy and I are going on a bit of a road trip though the Netherlands, Belgium, Luxembourg and if we have time, into Germany for a pint or two.

That sounds like it will be a really nice vacation.  No rush on returning the shell - we can deal with that when you return.

Actually I'm hoping that now you will take the MP tender casting, shave off the nasty ladder and then use that as the new master pattern for more "fixed" shells. 

Another needed shell for B&M locos would be the Walthers 0-8-0 tender.

[mmagliaro]

I think those are GREAT, and particularly those smokebox fronts are quite excellent indeed.
Nice job!

[JMaurer1]

I've been doing castings on and off for 20 years and I would NEVER attempt to cast a loco cab. It would need at least a three piece mold and the failure rate would be too high (and frustrating). I've cast boxcars and other rolling stock, but a cab! Easier to just buy one or 3D print it. Why are you worrying about the color, just paint them when done (I always cast in white and paint). Also why cast things that are available like the tender shells? You have more patience than I have. Nice job!

[peteski]

I've been doing castings on and off for 20 years and I would NEVER attempt to cast a loco cab. It would need at least a three piece mold and the failure rate would be too high (and frustrating).

Why a 3-piece mold?  I have been also casting my own resin parts (simple 1-piece molds) and that works even with serious undercuts in the mold. RTV molds are quite flexible and stretchable so parts  can be demolded even with serious undercuts.  As I see it, the cab only needs a 2-part mold.

[daniel_leavitt2000]

I think he was referring to open cavity molds like I am doing. I was close to making a 3 party mold for the cab, but figured out how to do it using a two piece mold. It was really difficult, but the results are starting to look good.

As far as the 0-8-0 tender, it's on my list, but I'm using lowered Rivarossi narrow bunker tenders for now. Problem with Walthers parts is that are not replaceable if something goes wrong.

[peteski]

I think he was referring to open cavity molds like I am doing. I was close to making a 3 party mold for the cab, but figured out how to do it using a two piece mold. It was really difficult, but the results are starting to look good.

As far as the 0-8-0 tender, it's on my list, but I'm using lowered Rivarossi narrow bunker tenders for now. Problem with Walthers parts is that are not replaceable if something goes wrong.

I still don't see how a 3-piece mold would be needed, even if you wanted to make a closed mold with a hole to inject resin and a vent hole elsewhere.

I'm glad to know you are working on a tender like the one used on that 0-8-0.

[daniel_leavitt2000]

The third mold part would have been an insert behind the cab to remove the undercut from the rear roof overhang. The issue I was running into was that the undercut was just to large to remove the resin parts successfully, and a split plug mold (where the interior of the cab plus a plug behind the cab to remove the undercut) was not giving my consistent results - I.E. the rear cab wall was not aligning correctly with the side walls. The last mold I tried seemed to fix this issue as I keyed it a bit differently, and used the rubber for only a single part.

There are still many issues with the narrow bunker tender that I have to work out. I may just scratch build one using various details lifted from the Riv tender.

[peteski]

The third mold part would have been an insert behind the cab to remove the undercut from the rear roof overhang. The issue I was running into was that the undercut was just to large to remove the resin parts successfully, and a split plug mold (where the interior of the cab plus a plug behind the cab to remove the undercut) was not giving my consistent results - I.E. the rear cab wall was not aligning correctly with the side walls. The last mold I tried seemed to fix this issue as I keyed it a bit differently, and used the rubber for only a single part.

There are still many issues with the narrow bunker tender that I have to work out. I may just scratch build one using various details lifted from the Riv tender.

I see that now - thanks for the explanation.

[daniel_leavitt2000]

I am in vacation so linking Flickr can be a bit difficult so I uploaded these to the Railwire.
You can see why I was thinking a 3 part mold might be necessary here.




Here, you can see a "glob" or rubber that did not separate correctly. This was on my previous mold. The new one has only one cab part. Tenders are a bit easier and I was able to cast three per mold.



Cab master with partitions and injector port.

[Ed Kapuscinski]

You know where these would be wonderful?

In the 2018 NTRAK Steam Annual: http://ntrak.org/Steam2016/index.html

[peteski]

Thanks for the photos Daniel, that makes things perfectly clear. I also like the interesting way you handled making that mold.