To those who have made their own silicone molds...

Signed-In Members Don't See This Ad
jbswearingen

jbswearingen

Member
Joined
Dec 10, 2008
Messages
752
Location
Bowie, MD
I made a mold from acid cure silicone yesterday, using Lego pieces to make the form. I just learned that silicone sticks to Lego pieces pretty well...I'm hoping all isn't lost!

My question pertains to cure time. It's been about 27 hours since I filled the form; the walls are about an inch thick; the bottom is about 3/4" thick. The bottom has skinned over thickly, but it is still squishy.

Any clues on how long I'll need to let it sit? I'm not in a *real* rush; my Silmar won't arrive until later this week, maybe next week. I'm just worried that it won't cure all the way through!

2013-01-08193016.jpg
 
Signed-In Members Don't See This Ad
I started making molds. I had no luck with the making a mold from store bought silicone. All I can suggest is using alumilite high strength mold rubber. I have had really good success with it.

I would leave for a couple more days, and see if it hardens up more. It is gonna smell like vinegar for a long time after until it fully cures.
 
at that thickness, it is likely to stay soft for several weeks, perhaps
a couple of months. If you can smell it, it isn't ready. When you can
no longer smell it, it still might not be ready.
That silicone is fine for repairs, but it isn't meant to be used at
that sort of thickness. Think of a bead of caulking.. it will skin over
rather quickly, but it stays soft for weeks. As you increase the
thickness, you increase the cure time, as it is an evaporative cure.
 
Brad: All I can say, Buddy, DON"T get in a hurry. I've had it take a LONG time, I'm guessing now on a couple or three weeks, maybe even a month or two on thick casts. I have quit using the caulking and gone to the RTV silicone from Alumilite. 24 hours or so and makes a MUCH smoother cast. It's a little more expensive but well worth it!
 
Last edited:
joefyffe said:
Brad: All I can say, Buddy, DON"T get in a hurry. I've had it take a LONG time, I'm guessing now on a couple or three weeks, maybe even a month or two on thick casts. I have quit using the caulking and gone to the RTV silicone from Alumilite. 24 hours or so and makes a MUCH smoother cast. It's a little more expensive but well worth it!
Click to expand...


Dangit!

Got a source link? Is that a 2-part mix? I'll gladly try that.

(edit)

Will baking at 150* help this thing cure faster?
 
Last edited:
jbswearingen said:
joefyffe said:
Brad: All I can say, Buddy, DON"T get in a hurry. I've had it take a LONG time, I'm guessing now on a couple or three weeks, maybe even a month or two on thick casts. I have quit using the caulking and gone to the RTV silicone from Alumilite. 24 hours or so and makes a MUCH smoother cast. It's a little more expensive but well worth it!
Click to expand...


Dangit!

Got a source link? Is that a 2-part mix? I'll gladly try that.

(edit)

Will baking at 150* help this thing cure faster?
Click to expand...

I haven't tried the baking. I would be afraid that if it had ANY air trapped (and it most likely will) that it would expand and ruin the mold. I've even had some of the commercial vendor molds puff up with me.:mad:
The Alumilite is an easy two part mix and pours very nicely. Read Alumilites information because they have a couple different "weights" flex ratings. I have used the #2 but haven't gotten my #3 mixed yet to do a comparison.
 
Well, I brought my toaster oven into work with me (I work in a large lab, by myself, so the stench of vinegar won't bother anybody but me). This way I can let it bake all day and be able to keep an eye on it. If it bubbles, so be it. As it is, it'll take weeks to cure, if ever, by itself. If this works, I'll call it a passing grade.

I think I'll try a mixing silicone next, though. This is just too much a PITA.
 
Try the Smooth-On. You can get small kits to try it out. That way
you don't have to spend a lot before you find out if it'll work for you.
You should be able to get a trial size (1 qt?) for around $25.
I'd try the MoldMax 30
 
So, it appears this mold will work after all. I've had it in my toaster oven at work the past two days. I'm lucky I'm the only one in the lab...it REEKS of vinegar...and it can be smelled in the hall.

It's firming up well, though I should have wrapped all the Lego blocks in plastic wrap. I'm glad I wrapped the "hollowing" piece in it, else it never would have come out.

Next time, though, I'll either buy molds or make them with 2-part silicone mix. This is just a PITA.

2013-01-11160022.jpg


2013-01-11160040.jpg
 
Last edited:
My first mold was made that way but not with legos. it took almost a week for mine to demold and even then it left some behind on two of the three sections. i have ben using tin sil 70-25 for making all of my other molds.
 
I was lazy...I didn't feel like firing up the table saw, jointer, and planer to cut wood pieces to size. That and it was fun to play with Emma's Lego set!
 
It's almost done...after four days of baking (and two days at room temp over the weekend), it still needs a few (several?) more days of baking to cure. Yes, it'll work. No, I won't be doing it this way again. It stinks!

A coworker gave me a large sheet of 1/2" UHMW board today; I'll make a few molds out of it...should be faster and easier!

2013-01-14135002Custom_zps1020d288.jpg
 
jbswearingen said:
A coworker gave me a large sheet of 1/2" UHMW board today; I'll make a few molds out of it...should be faster and easier!
Click to expand...

The UHMW will work just fine. Pre-drill your holes, though. Makes it
easier. Add a little soap or wax to the screws when you put it together
and that'll make it easier to take apart and put back together. a bit of
hot melt glue for the seams (just in case!) and smooth it out and
you're good to go. Mix up a little Vaseline in mineral spirits to brush
on as a release. It isn't strictly necessary, but it makes life easier..
 
:bananen_smilies035: Brad; Go to the library on this site and read my artical on Fast And Easy Mold Making. I tried the silicone once, what a mess !!!! I think my method will make the mold making a lot easier, less expensive, and more versital. No plugs, no weights, nothing needed to center your blanks, and the round bottoms and no connectiog bars saves resin. Jim S
 
plantman said:
:bananen_smilies035: Brad; Go to the library on this site and read my artical on Fast And Easy Mold Making. I tried the silicone once, what a mess !!!! I think my method will make the mold making a lot easier, less expensive, and more versital. No plugs, no weights, nothing needed to center your blanks, and the round bottoms and no connectiog bars saves resin. Jim S
Click to expand...

So.. what would you call that? a resin saver?
 
jbswearingen said:
It's almost done...after four days of baking (and two days at room temp over the weekend), it still needs a few (several?) more days of baking to cure. Yes, it'll work. No, I won't be doing it this way again. It stinks!

A coworker gave me a large sheet of 1/2" UHMW board today; I'll make a few molds out of it...should be faster and easier!

2013-01-14135002Custom_zps1020d288.jpg
Click to expand...

Honestly, the $30-40 you spend on a good mold is worth it. Rather than wasting time making a mold and money(and perfectly good legos).Then you can get straight down to casting. If you are planning on making tons and tons of blanks. Then making your own molds makes sense.
 
Last edited:
plantman said:
:bananen_smilies035: Brad; Go to the library on this site and read my artical on Fast And Easy Mold Making. I tried the silicone once, what a mess !!!! I think my method will make the mold making a lot easier, less expensive, and more versital. No plugs, no weights, nothing needed to center your blanks, and the round bottoms and no connectiog bars saves resin. Jim S
Click to expand...

I saw that and do plan on making some in that form. The problem is finding the time to clear room in the garage/shop to get to my ww'ing tools to make the form.

crabcreekind said:
Honestly, the $30-40 you spend on a good mold is worth it. Rather than wasting time making a mold and money(and perfectly good legos).Then you can get straight down to casting. If you are planning on making tons and tons of blanks. Then making your own molds makes sense.
Click to expand...

I (foolishly) hoped the silicone wouldn't stick to the Lego blocks. At least I wrapped the center piece in plastic wrap, so it didn't stick. I do hope to start making lots of blanks, both for pens I make and for selling. I already have commissions for three different color schemes; I'm hoping to make them this weekend.

I'll make more, but will first try the cutting board method. If I don't like that, I'll build more of the Lego forms and buy the two-part silicone mix. There are many ways to skin a cat; you have to find the method that doesn't make the biggest mess!
 
NewLondon88 said:
plantman said:
:bananen_smilies035: Brad; Go to the library on this site and read my artical on Fast And Easy Mold Making. I tried the silicone once, what a mess !!!! I think my method will make the mold making a lot easier, less expensive, and more versital. No plugs, no weights, nothing needed to center your blanks, and the round bottoms and no connectiog bars saves resin. Jim S
Click to expand...

So.. what would you call that? a resin saver?
Click to expand...

Do I sence a little intrapment here !!!! I show a method of how to make a mold box that can be easily changed to fit any size or number of pens you want to make. I am not selling the mold box or the molds I make with them, although I have had many offers to do so. Since this improves on your design and saves even more resin, and I don't sell anything, I am not any danger to you. I do have your molds and they work just fine. The only reason I made my own was because every time I tried to order your's, they were out of stock. I gave up after 3 months, and made my own. For anyone who doesn't want to go through the hassel of making their own molds, I highly recommend yours. Jim S
 
Last edited:
Molds

Brad - nothing has ever been accomplished by not trying. I have been following your posts and learned quite a bit.

If you learned along the way and wound up with a workable mold - then kudos to you. If all you gained is knowledge - that is priceless, too.

Thank you for sharing the process and your learnings.
 
You're quite welcome! I enjoy sharing what I've learned as much as I enjoy learning. I learned this last night--putting together two molds from a sheet of UHMW is much faster than curing silicone putty. I'll need to go back and seal the seams, as it doesn't cut very cleanly, but I think this will be my method for molds. I made this pair deep so that I could double the number of pen blanks in one pour and so that I can make ice cream scoop blanks and such that require larger blanks.

These are 3/8" sheet with 6x3/4 wood screws. The holes were pilot drilled and counter sunk.

2013-01-15224900.jpg
 
Last edited:
I've made this type of mold in the beginning out of delrin.

I've found the screws to be a PIA and I don't use them anymore.

I take the delrin sides and bottom (and my sides sit on top of the bottom) I use silicone AMAZING GOOP put a small bead on all joints then simply tape the mold together with duct tape.

The finished cast pops rite out and I can usually get 2 or 3 cast before I have to reseal the mold. The GOOP holds plenty tight and seals but comes apart easily when I need it too. I have gotten hundreds of cast from these molds. Were as the one with the screws stripped out on me in short order.
I will post a few photos later when I have time if wanted.

Some times simpler is better.

.
 
Last edited:
Bruce--

Thanks! I'd appreciate pics, and will keep this in mind when/if these screws strip out and fail.

When I turned my first pen a decade ago, I thought it was a simple process. Boy, was I wrong!
 
Mold looks good..
As I mentioned, a bit of soap or wax on the screws (pre-drill!) will
make them easier to remove. And you DO want to seal the seams,
otherwise the stuff gets in and sticks. I have plenty of 'oops' to prove it.

ps .. if you try a silicone mold, ditch the Legos and make yourself a
block out of wood. Sand it will, even polish it. Give it a good coat of
butcher's wax to seal it. Much better as a master, as you don't have
to turn off those bumps!
 
Last edited:
Yup, I spent an hour last night sealing (with hot glue) and testing (with water) the seams. They appear to be whole. If all works out as I hope, they'll have curing PR in them tomorrow.
 
plantman said:
Do I sence a little intrapment here !!!! I show a method of how to make a mold box that can be easily changed to fit any size or number of pens you want to make. I am not selling the mold box or the molds I make with them, although I have had many offers to do so. Since this improves on your design and saves even more resin, and I don't sell anything, I am not any danger to you. I do have your molds and they work just fine. The only reason I made my own was because every time I tried to order your's, they were out of stock. I gave up after 3 months, and made my own. For anyone who doesn't want to go through the hassel of making their own molds, I highly recommend yours. Jim S
Click to expand...

What entrapment? :confused:
Anyone who has a ResinSaver can easily see how to make one. They're
not hard to reverse engineer! In fact several people have asked me
about problems they've encountered while making their own. I've
answered every question they asked. That doesn't mean I'm excited to
see a tutorial on how to put my little fledgeling operation out of business..

For the record though, I no longer make the molds. Wolftat took over
the operation last year and he makes them now. I'm not sure why you
couldn't get one, I know Timberbits and CSUSA keep them in stock. And
when I was making them people often ordered them direct from me.
I'm sure Neil also sells them direct. I don't recall you contacting me
about them. I wouldn't have been out of stock. :tongue:
 
Big thanks to Jon (GoodTurns) for helping me out today. We mixed up a batch of red and black swirl...ended up being red and gray...too much pearl. He re-poured another red/black batch later today. My buddy, who is new to turning, was also there. His mother painted a couple of tubes and Jon showed us how to cast them in clear resin, with plugs.

With his help, I now have a pretty good idea of how to do it on my own. Time to start making a mess!
 
NewLondon88 said:
plantman said:
Do I sence a little intrapment here !!!! I show a method of how to make a mold box that can be easily changed to fit any size or number of pens you want to make. I am not selling the mold box or the molds I make with them, although I have had many offers to do so. Since this improves on your design and saves even more resin, and I don't sell anything, I am not any danger to you. I do have your molds and they work just fine. The only reason I made my own was because every time I tried to order your's, they were out of stock. I gave up after 3 months, and made my own. For anyone who doesn't want to go through the hassel of making their own molds, I highly recommend yours. Jim S
Click to expand...


What entrapment? :confused:
Anyone who has a ResinSaver can easily see how to make one. They're
not hard to reverse engineer! In fact several people have asked me
about problems they've encountered while making their own. I've
answered every question they asked. That doesn't mean I'm excited to
see a tutorial on how to put my little fledgeling operation out of business..

For the record though, I no longer make the molds. Wolftat took over
the operation last year and he makes them now. I'm not sure why you
couldn't get one, I know Timberbits and CSUSA keep them in stock. And
when I was making them people often ordered them direct from me.
I'm sure Neil also sells them direct. I don't recall you contacting me
about them. I wouldn't have been out of stock. :tongue:
Click to expand...

I wish you the best in any health, wealth, or ventures that you have going on!!! I don't feel it is the best interest of this site to continue this conversation any farther. I made my statements, you made yours, let's leave it at that. I would suggest however that you change your bottom line so it doesn't lead someone to a web site that has no ResinSaver connections. Peace !! Jim S
 
You must log in or register to reply here.
Back
Top Bottom