New mold material...check it out!

Thank you very much!   I was unaware of this product, but through the wonder of Amazon's one-click shopping a pack will be here Tuesday for me to experiment with.  This looks to be exactly what I need for some of my scratchbuilding work. 

Thank you!

Lee...

Just extricated some reefer door latches from the mold...incredible!

Still a bit on the learning curve.  Some of the parts have evidence of a small air bubble or two having been trapped as the JB Weld set up.  This time I have spent more time prodding the just-mixed weld material into the mold cavity.  We'll see if that helps keep bubble spots from occuring. 

It's not a biggie, anyway.  I added a dot of fresh JB to the bubble cavity.  When it's fully cured hard, a couple of swipes of the jewelers file or slices with a fresh #11 blade should take care of that and salvage the part.

This is fun!  I love trying new tools, techniques, and materials like this, too!!

You know what that reusable mold material reminds me of...low temp hot glue gun sticks, but rectangled shaped.

I've used the alumilite mold putty that's 2 parts...kneed it together and press, but this stuff I've used is not reusable.

Matter of fact, I really kneed to copy a 1/50 mack AC nose off of a diecast truck for an On30 switcher project that's coming up...

Looks like the stuff used to make mouth guards.

Cool idea!

Dave

Thank you for the link. The mold making material looks like it could be very useful but I've found two part liquid resin better than epoxies like JB Weld or the compound used in the video. The sword shown in the video could have been made by pouring the resin into the same mold with little trimming required afterward.

This post war car door was cast into a mold with only the side edge open. Only the side edge had to be trimmed off.

Pete

It will never replace rubber molds and resin for the typical O scale building and structure applications. But looks like it is fast and easy for some  small projects.

Exactly!  It's not in the same application league as rubber molds, for sure.  But when I came up short on those reefer door latches...having a flat side, shallow detail, and small size...bingo! 

I just de-molded my second set from the same molds.  And, just as I suspected, the prodding of the JB Weld into the cavity with a rounded toothpick eliminated the tiny bubble-cavities.   The feature quality of the parts from the first and second 'pours' are identical under my Optivisor.  So, it looks like I can make several more before...and only perhaps...I have to remake the mold to renew its integrity.

BTW, I'd take some pictures of the original and clones and molds if I could figure out what I'm doing wrong in taking/posting pics.  My wife, the geek in the family, thinks she's found our problem.  (Me, probably)  It has nothing to do with not being able to follow the simple OGR steps per the Tech Forum.  We apparently have a local networked home computers problem in sharing files.   I'll post later if possible.

Also, re the Instantmold video on making the sword mold...I'm sure we all could improve upon the demonstrated technique.  We (LHS) sell a full line of the Alumilite products.  In fact, the helpful Alumilite folks have come to our store several times to hold a 'how-to' demonstration for interested customers.  Their products are very popular among several hobby avenues.  But, this Instantmold is so simple, so fast, so re-usable, it's going to be a favorite at my workbench, for sure.

KD

KD, I just checked out the Alumilite web site and was amazed at the variety of product they offer. Which of their casting resins would you recommend for making model RR parts?

Pete

I've been a big fan and user of Alumilite for the last 7 years.  It produces exceptional castings that are very durable.  Its quick too!  20 seconds to mix, you have about 60 seconds to pour before it starts curing, and the casting is fully cured and ready to de-mold in about 5 minutes.

A neat trick that is not well known is that you can paint your RTV mold with acrylic paint; let the paint dry; and then cast your piece.  This causes the acrylic paint to chemically bond with the Alumilite to produce a piece that has your painted detail actually "embedded" into the plastic.

The only downside that I have found with Alumilite is its shelf life after opening the casting resin and catalyst.  Despite what they say, I have found that the resin tends to cast softer or produces a slightly tacky part when you are using resin and catalyst that is more than a couple of months old after opening.  Some parts just don't seem to fully and quickly cure as fast as fresh resin and catalyst.  I can't tell you why, only that I have had this issue with old resin.  I would recommend that, unless you are going to be casting enough pieces or large enough items to fully use the large bottle of the resin and catalyst within a month or so, you purchase the mini casting kits to get the smaller size bottles.  The per ounce cost is higher, but you waste less resin.

Costs... I buy my Alumilite from Hobby Lobby.  If you use their 40% off coupon, the Mini Casting kit will cost you less than $19.00.  The Mini Casting kit includes everything you need... enough RTV silicon to make a 4" x 4" x 3/4" mold, modeling clay to seal up your mold box, Popsicle sticks for stirring, (3) measuring cups, and enough resin and catalyst that you can easily make dozens, if not more, castings.

This past Saturday evening, I made a mold for the end doors on some intermodal containers that I'm scratch-building.  In about an hour and a half on Sunday afternoon, I cast a dozen of these parts to use.  All together I used about 60 ml of resin and catalyst... barely 25% of the small bottles from a mini casting kit.

Interesting. NOW do these molded pieces come out a bit flexible? the reason why I ask is I am looking to make some MTH corrugated pannels that are found on their autoracks. the backs of those pannels have tabs that snap in...thus plastic material need to be a bit flexible and tough as well.

can you do building kits by casting your own pieces with this kit or would you need to buy a bunch and a giant tubes of rtv for molds  i know i would love to do this and make a bunch of half size ones for backdrop

Cured Alumilite would be about as flexible as a similar sized piece of styrene at the same thickness.  It *is* possible to slightly alter the 1:1 base to catalyst ratio to get a more flexible cast part.  I found this out by accident by occasionally not getting all of catalyst out of the measuring cup when mixing.  When this happens, the cast part tends to take on a slightly greenish hue... and takes longer to fully cure out.  You would have to experiment a bit to figure out how much to reduce the catalyst ratio.  But, be aware, we are only talking about a matter of few drops difference.  Also, if you don't get enough catalyst mixed in, the part will not fully cure and will be tacky.  At that point, it is a junk piece.

You can cast whatever size of item that you need.  It is just a matter of having enough RTV to fully surround your master and to make sure that the RTV is about 1/4" to 1/2" thicker than your part.  When I make my mold boxes around the master I'm going to cast, I allow about 1/2" all around the outside of master.

You can buy RTV silicon typically in 1 lb. containers.  The Alumilite comes in small and large bottles.

Having messed with 1/25 scale semis...ok, still do...I've got some silicon tires that are nice and flexible. You really can't get hard resin to act soft without ruining it{lack of catylist}...you can take heat and twek it to a new shape but it'll harden like that.

I can tell you if you want a noodle like resin piece, soak it in brake fluid for a week....btw- "don't do this!!!!" I had an old semi truck cab that had piant on it, I was out of my usual stripper so I tried brake fluid like I used to use on the painted styrene cars in order to remove they're paint...all I got was a useless, wobbley cab from that and it never hardened up again.I could nearly push the front of the cab into the back of it and it tore in a spot. You can do it, but I highly advise against it...waste of a good FWD cabover for me but a valuable lesson learned{would rather of learned the lesson and kept a good cab too!}