Using GF to forge brass stamps

Hand pour. Mostly petrobond sand with wood or foam patterns ( i don’t have a kiln).

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Sorry, no. I did everything myself (with the exception of the photo etch). I think hiring that job out though is the best option for your circumstance. You only need a limited number of designs, and casting can get you into a deep hole of equipment/education needed.

This is not a recommendation, just results of a google search.

Have you considered lurking on a leather workers’ forum? I would expect the topic has been discussed there many times. I lurked around one once. Some of those guys get pretty grumpy.

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Well, I was more interested in the possibility of my Glowforge being the catalyst- able to make really intricate carvings that maybe could then be cast in brass.

There’s more people with a GF here than a leather forum, so I figured this was the best place to ask the feasibility of that question.

I’m on a leatherworking reddit too, but nobody answers my questions there…

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I think you might be talking about sand casting. If that is the case then you can use the gf to make models and skip the wax and put the model ( acrylic probably best ) into the sand to make an impression. The sand creates the mold to pour the brass into.

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Like this except use the GF to create the masters
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You may find this post of interest (also, do a forum search for casting to find more):

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To be clear I meant the best company to cast brass stamps made for leather.

I was just going to go find that to post. :slight_smile: I’ve also engrave acrylic for the molds, but of course it leaves a texture behind. To avoid it, I’ll make a master by gluing the pieces together and then make a silicone mold out of that.


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Wait- are you saying you used engraved acrylic as masters for even the wings above?

Cast in sand? What type of metal did you use for those examples?

When you say “glue the two halves together and use silicone” what do you mean exactly? You are glueing two acrylic halves together or… I’m lost.

Your prices turned out really cool

I’ll be digging into this post immediately! Thanks!

Oh sorry, I should have been more clear.

The skeleton dogs were cast with low-temp pewter from a store called RotoMetals and the link is in the post I shared below. (Check the store pricing before ordering from Amazon because it was much cheaper ordering it directly.)

The feathers and base of the wing were cut out of wood, and then I glued them together and made a silicone mold out of that. Pewter is easy to sand, but doing it this way gave me a smoother result than I could get with making a mold of an engraving. Of course, a lot of this won’t work the same for brass since it melts at such a higher temp, but maybe it’ll give you some ideas.

This is the wood wing and wood cross glued into a box so I could make a mold of it. (I put the cross in upside down and had to mold it a second time. :roll_eyes:)

The silicone molds.

The final metal castings.

This was my first attempt at casting.

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Your castings are really incredible! I got discouraged after my one try. I had used Mold Max 60 high temp casting silicone and I think it was too old or something. I could hardly get it mixed before it got too thick for any bubbles to come out. (I don’t have a pressure pot or vacuum pot.) My castings were just a mishmash. What mold making silicone are you using? I’d like to give it another try.

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yes it will work. you are on the right track. I believe someone here made a (sorry the term has escaped me) metal square where you put hot melted metal in to, however, his was made out of acrylic. He first engraved the acrylic then used a low melt temp. metal (mostly nickel) and came out with the finished shape that the acrylic had been engraved into. I hope this makes sense. but this is the same idea you have.

In my experience (limited) the problem is getting the wax back out in one piece. Might be able to do it if you treat the acrylic as sacrificial…

You’re supposed to burn the wax out.

You burn the wax out once you’ve made the final mold around it. My experience is about casting the wax in the acrylic mold/pattern to make the positive in the first place. Maybe needed better finishing or release coat or some other trick.

hi JimSocks and all,

this caught my eye as i’ve been making acrylic blanks on the GF and reproducing them in pewter and bronze. apologies if i repeat what others have said that i may have missed. i use delft clay, which is finer than most casting sand, reproduces detail well, and requires less finishing than coarser media. the picture below shows an acrylic model burned on GF, pewter and bronze castings of it, and a different design created by stamping objects directly into a delft clay mold made from a blank model – these are 1.5" diameter. below are some stamps i’ve made in bronze for marking clay molds. i don’t know whether they’d hold up under the stress of your stamping process for leather. the bulbs at the bottom are the buttons, and the rod is the sprue. to make them stronger for stamping, you could make the sprue thicker and perhaps more conical to prevent bending under pressure.

pewter/white metal is easy to melt, stays molten nicely for pouring, and captures great detail. it’s nice for jewelry, but too soft for stamping leather. but it could be nice for prototyping and sending out for professional casting. the delft clay captures nice sharp detail from the acrylic model (burned at 340 lpi), as reflected in the pewter model in the picture. the pewter model is straight from the clay mold with no finishing; i did polish the acrylic surface before burning the design with the GF. (it’s my understanding you can also pour white metal into silicone molds, though i haven’t tried it.)

the clay mold for the bronze was equally detailed, but the bronze model captures less detail. with only gravity to hold the bronze in the mold (as opposed to vacuum or centrifugal force you might use for investment casting), the metal contracts as it cools, pulling out of the mold a bit and resulting in some loss of detail. if you wanted sharper edges in the design for the leather stamps, you could grind down the surface to take off the rounded edges. i did this on the model in the lower right using a medium silicone abrasive wheel. this piece was made by pressing objects like keys and buttons directly into a delft clay mold made from a blank model. you could correct for the loss of depth from the grinding by burning your acrylic model a little deeper if necessary. in the darker, unpolished areas towards the middle of the fourth model, you can get a sense of the fine grain that a smooth surface produces in the clay.

i agree investment casting is an adventure! i enjoy it and it produces great results. another of its advantages is that it allows undercuts in your designs, which sand casting doesn’t – but i don’t think that would be an issue for your application. if you think it will give you the detail you want, you may find delft clay casting easier, cleaner, safer, faster for one-off pieces, and more economical than investment casting. the biggest technical challenges would be getting your ventilation in place and safely generating the heat needed to melt the bronze.

white metal does not char the clay due to the low temperature, so all the clay from the mold can be reused. bronze will char the clay, but the uncharred clay from the mold can be reused.

here are links to the materials i mentioned:

bronze casting grain (MSDS says 90% copper, 10% tin)
https://www.riogrande.com/product/ancient-bronze-casting-grain/706051

white casting metal
https://www.riogrande.com/product/aqua-clean-casting-metal/750150

delft clay casting kit
https://www.riogrande.com/product/delft-clay-casting-system/705136

silicone abrasive wheel
https://www.riogrande.com/product/EVE-Silicone-Black-Polishing-Wheel-Medium/332731

here is a good and approachable book on DIY casting:
Practical Casting: A Studio Reference, by Tim McCreight

cheers :slight_smile:

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This is an amazing write-up- thanks so much!

you’re welcome, i look forward to seeing your work!