1959 Les Paul Build

[preeb]

Disaster stroke...
ALWAYS READ WHAT IS SAYS ON THE PACK DOWN TO THE SMALLEST LETTERS... DARN!!!
I have specifically asked the stupid guy at the store for an RTV silicone releasing agent and he gave me the opposite... a silicone based releasing agent which is like glue to the RTV... so... the two parts are now one...

I had to carefully cut the ring out of the mold. What I did noticed is that there are zero air bubbles and the detail is phenomenal so I'll give it another chance... not before kicking this guy's a)s over the phone... I could really strangle his little neck (-;

Here's the mold after I cut it...



I made a proper size ABS box this time and did phase 1 all over again...



I'm going to replace the agent but I'd give WD40 and Petroleum Jelly a chance first.
I used each on each side of a dry TRV and see if they separate when curing...



I should stick to woodworking... (-;

[mgdesigns]

Gil - very clean looking mold. I cannot wait to see you the top half turns out. I made an RTV mold for a custom starfish wax pattern I had made that was going to be cast in 18KY gold, and I used about $40 worth of 2 part RTV. It never did cure. I separated the mold, and it oozed out all over the place. I used it because I did not want to destroy my original wax. Then when I got the casting back from the company in NY they sent their mold. Thanks for the great info, and thanks Ed Hawley for that lead to the company here in the states for mold materials. Occasionally I may have a need for this stuff.

OMG - I just posted this and noticed you had disaster strike with the top half. I was wondering what release agent you had used. Apparently not the right one. I did see a compound in jewelry trade magazine once, called citrucel, that was a quick RTV. It was an organically based compound, that you could smear a dab on glass, press your object in, let sit about a minute, then smear the top half on, and this citrucel wouldn't even stick to itself. I have looked for this stuff for many years and jewelery company that sold it in Memphis, TN was sold out and no longer can I find it anywhere.

[preeb]

OK... this RTV silicone is one persistent stubborn material... it loves itself so much that nothing will stand in its way... it passed through the wd40 and the petroleum Jelly like there weren't even there... No luck... but I'm stubborn too.. so tomorrow I'll get the right stuff for a clean separation.... and I'm so sorry this is taking so long... bear with me... The target is a fresh new set of 100% correct home made M-69's (I hope) (-;

[PlutoLex]

I think it gives the rest of us hope to see that not everything works perfectly for you the first time ;) Good luck... though I don't think you need it. Thanks for sharing the build, it's very interesting and informative!

[Mister B]

Gil, a technique I've seen used to create a good split line in a silicone mould is to use adhesive tape. You stick tape where you want the split to be then cast the mould in one go, using a couple of thin wires to suspend your part. When the silicone has set you cut to the tape with a sharp knife releasing your part and creating the two halves. The tape gives a perfect split.

[preeb]

Originally Posted by Mister B

Gil, a technique I've seen used to create a good split line in a silicone mould is to use adhesive tape. You stick tape where you want the split to be then cast the mould in one go, using a couple of thin wires to suspend your part. When the silicone has set you cut to the tape with a sharp knife releasing your part and creating the two halves. The tape gives a perfect split.

It's a good way for some shapes but I couldn't figure out how to use it for a pu ring. If you can think of a way to do this please let me know where to place the tape.

[ChancesR]

You could try furniture or auto body wax. I've used both as release agents for silicone molds with good success, might not have been the same type of silicone though.

[preeb]

I think I'll do the right thing and get the professional correct material tomorrow.
This is definitely one of those times where you can say: "The right tool for the right job" (-;

[Mister B]

It's a good way for some shapes but I couldn't figure out how to use it for a pu ring. If you can think of a way to do this please let me know where to place the tape.

The general rule as far as I could see (I've never done it myself) was to put the tape where the real split would be on an injection mould tool. I'm not as familiar with the exact geometry of a pick-up ring as you are, but from the photos I'd guess the split would be along the bottom edges. The tape would need to stick to the thin edge radiating out. It may be simpler to use a single, wide piece of adhesive film to split the opening.

[pinefd]

You're right, Gil. I've worked with that stuff a fair amount, and have also found that having the right release agent is very important.

[mgdesigns]

Talc powder? I've used baby powder in the past to create a separation plane in vulcanized rubber molds. Good luck, and I am sure the manufacturer has the secret ingredient.

[preeb]

I forgot to mention earlier... regarding magnet charging, I used a big 4" X 1" X 1" N50 magnet which was dangerously strong and fully charged the bars in a split of a second.
I couldn't use it for discharging either because of the insanely strong field.
so I decided to use a weaker 3" X 1/2" X 1/2" N40 magnet from here:
http://www.amazingmagnets.com/p-463-p500dx.aspx
and it's the perfect tool for getting the 5L and 4 bars partially charged.
I get the full charge in about 10 seconds and a slight discharge from about 1" away.

[preeb]

Originally Posted by Mister B

The general rule as far as I could see (I've never done it myself) was to put the tape where the real split would be on an injection mould tool. I'm not as familiar with the exact geometry of a pick-up ring as you are, but from the photos I'd guess the split would be along the bottom edges. The tape would need to stick to the thin edge radiating out. It may be simpler to use a single, wide piece of adhesive film to split the opening.

No can do... what about all the little tool marks at the bottom edge of the ring? The top isn't good either because of the holes and round over edge..
Unfortunately, that's the way it is with guitar building.... there's always an issue... (-;

[preeb]

Originally Posted by mgdesigns

Talc powder? I've used baby powder in the past to create a separation plane in vulcanized rubber molds. Good luck, and I am sure the manufacturer has the secret ingredient.

How? did you just spread it over the whole thing?
What about the smooth part area?

[preeb]

Check this out.... LOL
http://cgi.ebay.com/ws/eBayISAPI.dll...E:B:SS:US:1123



I was wondering... How does it feel to strip an $850 screw...

[Mister B]

No can do... what about all the little tool marks at the bottom edge of the ring? The top isn't good either because of the holes and round over edge..
Unfortunately, that's the way it is with guitar building.... there's always an issue... (-;

I was forgetting you fanatical attention to detail (again). You're right, the tape would obscure tooling makes, it also leaves a tiny witness line that has to be removed. Good luck with your original method, I'm sure it'll work out fine.

[preeb]

Thanks Mister B, your input is appreciated!

[mgdesigns]

Originally Posted by preeb

How? did you just spread it over the whole thing?
What about the smooth part area?

After your bottom half has cured, powder the top surface liberally, then tip over and remove most of the excess. Then, with mixed 2nd batch carefully pour in. If you have enough baby powder on it the 2nd batch should not stick to the 1st. Try a small sample and see if it'll work first. This is what I did for the rubber sheet material from Castaldo. It may work for the liquid, too.

[preeb]

Originally Posted by mgdesigns

After your bottom half has cured, powder the top surface liberally, then tip over and remove most of the excess. Then, with mixed 2nd batch carefully pour in. If you have enough baby powder on it the 2nd batch should not stick to the 1st. Try a small sample and see if it'll work first. This is what I did for the rubber sheet material from Castaldo. It may work for the liquid, too.

How do you keep it off of the part itself? Do you wipe it off leaving powder on the RTV section only?

[mgdesigns]

The thin layer of dust on the part should not affect the translation very much. You may have a slight matte finish from the dust, but very sligt because the baby powder is so fine. Try it on something else first, and let me know. Maybe a plastic guitar pick, in a small 2" square container? Oh, and if this works like I think it will, you won't have to cut a mold apart, it'll just separate.