What type of mold would i need to cast fenders and hood of M35A1 or 2
truck. Two part mold Im not sure. Thanks

Keenan

G'day Keenan,
Give this a go.
Squash Mold

Cheers Jason

It really depends on how many you need. you can make a 1 part mold.. f you only need a few.... if you want a bunch... go 2 (or more) part.....

There's another far less expensive and simpler way to do fenders and hoods, provided they don't have much detail, or at least detail you can add afterward. Have you thought of heat forming the parts? I did some fenders to convert Tamiya's halftracks to M5's several years ago. They had the flatter contoured fender associated with the halftracks produced by International.
All you need is a canning jar-the kind with the screw on lid with the removable center-and a basswood form.
Carve the fender/hood out of the wood and sand it smooth. It has to be just slightly smaller than the part you want.
Take the canning jar and replace the center of the lid with a disc of .010 styrene. Place it in a warm oven until the plastic starts to sag. Now plunge the wooden form into the plastic. Let it cool, and pull the wooden form out. You'll have to trim it, and chances are only one out three tries will work, but it will work.
If you don't have a canning jar you can still accomplish this a number of ways. You can make a wooden frame for the plastic, or modify a wide mouthed jar by simply cutting the entire center out of the top.

How about this feature

Vacuu forming

Thanks guys, im wanting to make some molds for the 5-ton conv. I scratch built the conversion using Daves (animal) feature. Just want to make some copys to speed up the process. I looked at some photos in the gallery of some of his molds wish I knew what process he used does he still visit the site im sure he would be glad to help. Do you think the vacuu forming would work for this.

If you can post a few pictures of the parts, I might be able to help point you in the right direction.

Also, if you just need general casting and mold making info, there's a bunch of stuff on it in my self-published book: https://aeroscale.kitmaker.net/forums/114741&page=1

Here is one picture dont no if it help you help me. Im sure its possible to copy the whole front end which it might be easier than the seperate parts.


Thanks Keenan

You would do better to seperate the parts, and make molds for each part. But since they're together like that and the photo is really small, I cannot give you a good answer as to how the mold halves should be split or laid out.

You could take a look here and maybe get some ideas. I've made a few molds. Easier to mold individual parts than whole assembles.





Joe

I have a quetion about the one part mold. When the parts are attached on a tree like structure for molding, how do you get them out. Does the mold strech or doy you have to cut it? The example are on this pictures:
http://news.webshots.com/photo/2471019520034293688cvoTpg
http://news.webshots.com/photo/2462629790034293688LfYbxV
http://news.webshots.com/photo/2530545280034293688BmFTcV

I mean, how do you get the castings out?

In the first pic you can see a slight need to cut just a little bit of the mold. I've done this quite a few times and t works.

Joe was the one I learned alot of my casting from thru chatting with him online.

Would a seam be visible on the castings afterwards?

Generally all parts will have a mold seam. Mine have more of a thin flash of resin where the molds part. Easily removable with a knife or file. The only tools needed for my castings.

How do I get the parts out?

I use the 10-1 high strength rubber from Micro-Mark. It's very strong and stretchy. For most parts I do what I call a closed mold method. That is when the mold closes over the part with only the thinest opening for air to escape. I mount tires on pins. Other parts are mounted on thin strips of plastic only thick enough to support the weight of the master. Parts that are small or thin I mount on very thin packing tape. All these are mounted on a resin reservoir block. After molding the master the reservoir will break off from the master. Then I cut the mold down to the master until I can stretch the mold enough to get it out.
Big or odd shaped parts like fenders and cabs require 2 or sometimes 3 piece molds.

I do highly recommend the investment in a pressure tank if you plan on making lots of molds and parts. It's been key to what I can do.



Joe

Yep. Joe's methods do work........ and the pressure tank is a damn nice investment. A used paint tank on Ebay or a new one like: Paint Tank Can be converted to work easily. no more than 25-30 psi is usually required.