Hex bolt head in resin mold questions

[ChuckT]

I want to cast some tiny hexagonal bolt heads in resin to then use for various projects. I want to make the mold out of silicone and I am able to do vacuum degassing for the silicone mold material and pressure casting for the resin. I hope this will give me the good results I desire.

 

My question is, what is the best way to make the mold?

 

My hex bot head is attached to a stem, so I can drill some holes in plastic to then mount my stems into, thereby raising the bolt head off of the plastic backing sheet. This would give me a molded bolt head that will have an undercut.

 

Will having a mold with a slight undercut be ok?

 

Will the pressure casting cause the resin to fill the mold completely or do I need to add a vent at its deepest point to let the resin flow in and through the mold cavity?

 

Any other ideas on how to do this successfully?

 

Thanks as always, Chuck

[Vandy 1 VX 4]

Hi Chuck try these links for help in what you need. The first one is a supply Co. link. The second is a

tutorial on molding items.

 

 

http://www.smooth-on.com/

 

http://www.youtube.c...ser/SmoothOnInc

[ChuckT]

Thanks!

[dodgem37]

I make hex nuts with a bolt shaft extending thru its face and plain hex nuts from tank roadwheels/drive sprockets by using the following method:

1. Blank off the axle hole.

2. Cover hex nuts with molding agent. This way you know there are no air pockets trapped on the hex nut.

3. Pour molding agent into the roadwheel 'cup' level with the roadwheel lip.

4. Let set.

5. Remove mold.

 

You can use as many of the roadwheels/drive sprockets as necessary to make hex nuts. If you want a hex nut without a bolt shaft extending thru its face then trim off the extension either on the casted part or on the kit roadwheel. Different tank kits have different size hex nuts. The variations are endless.

 

I use a toothpick to insert the resin. If you have a shaft extending thru the nut face you will need to work the air bubble out of the shaft. Regular nuts do not have this air trap. Once you cast the nut sand off any over pour on a flat surface. I use a tweezer to squarely hold the nut while sanding. There may be times when you don't sand the overpour so perfectly, but it's easy to adjust the sanding angle. If you mess up, you've got many other bolts to work with.

 

Sincerely,

Mark

Edited January 14, 2013 by dodgem37

[ChuckT]

I like this method! Thanks for sharing it, Chuck.