Silicone Molds for Lead Jigs

Started by jcool3, October 17, 2015, 02:48:28 PM

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jurelometer

Quote from: gstours on November 04, 2018, 01:44:11 AM
   Thanks for the recent reply.   I,m trying ti do a easy mold to cast a 'Pattern" that I can use as an origional,  and possibly share to others as they can make thier own mold their way.   I,m learning.  the sand cast might be gppd for something simple like what i,m planning on.   Just saying.   I hope others can learn from my mistakes. 
   Currently i,m making several octipus heads Masters, different sizes,  when finished i will post stuff.  everybody likes a laugh! :o

If you are wearing pants when you pour the metal,  you will already be ahead of the youtube "experts ".  ;D

Looking forward to see what you come up with.

-J

Cor

Quote from: Leerie18 on November 03, 2018, 06:54:48 AM
Hi all, excuse the basic question, but I was wondering if there are any special considerations for the through-wiring?
Currently my loops are cropped close to the ends and bent-in... no failures yet, but then there is a dearth of large fish in my life!


It looks like 1.6 mm SS welding rod you're using which is pretty strong.   Even 1.2 mm should be adequate and its very unlikely to tear out on a fish.
However, I would make the "loop" in the wire about double your size.   Sometimes the wire does not get covered with metal properly, or you have a problem where your wire is not hot enough and the metal does not flow nicely around the wire to fill the ends of the mould.
Cornelis

Leerie18


[/quote]
 Sometimes the wire does not get covered with metal properly, or you have a problem where your wire is not hot enough and the metal does not flow nicely around the wire to fill the ends of the mould.
[/quote]

Your advice is spot-on thank you! Repeated pour failures earlier this morning exactly as described.
Will revisit throughwire set-up and start again. Silicone mould still in good shape, been using a fine pre-cast mould coating of talcum powder each time.
LBG addict!

jcool3

Quote from: Leerie18 on November 03, 2018, 06:54:48 AM
Hi all, excuse the basic question, but I was wondering if there are any special considerations for the through-wiring?
Currently my loops are cropped close to the ends and bent-in... no failures yet, but then there is a dearth of large fish in my life!


i changed all my silicone molds to pouring thru the end instead of middle.  Avoids a lot of those problems.

gstours

  Thanks for the info,   Im making some molds very soon.  simple designs,  butt everything that helps,   helps.   right?? :-\

Gadget

Have read everyones ideas I thought I'd post up what I do here in Western Australia. I've been making my own leadheads since the late 70's and in the last 10 years got into deep drop jigs,flat fall and flutter jigs all made at home from hand carved balsa masters. Originally I was able to get hold of Dow Corning RTV 5160 i think was its number. High temp resistant and  long lived .(those moulds are as good today as when I made them in the 70's) The silicone gurus over here tell me that the formulae have changed for silicones and the long lasting stuff doesnt exist any more. I now use a Product called Wacker 4670 made by Barnes Corp. Its a fawn colour(shore 60) and works well so far but apparently wont have the longevity of the Dow Corning stuff. If I'm making vertical jigs I make the mould casing out of 40mm,50mm or 60mm  white poly pipe.Seal off the bottom with Gaffer tape,suspend your master inside the pipe and then pour the silicon to the top. let it set and then using a hack saw cut a slot lengthwise down the pipe to release the mould with the master inside.Once the mould is out, cut right around with a stanley trimmer and extract your master blank.Then carefully carve a pour entry hole into the silicone mould (essentially you now have a round two part mould)Also cut a hole in the poly pipe in the same position plus a small vent hole at one end of the mould.
The you rig your wire put the two halve back together and slide back into the poly pipe.I then use a clamp to keep things together and pour the lead.
Getting the finished jig out requires gloves and I use a piece of large dowel to push the mould back out of the poly pipe.
I've made dozens so far and have not had a jig mould disintegrate yet and i'm using pure lead so they are wearing a fair bit of heat 700degrees plus .
Getting the lead real hot gives the best results and the mould itself needs to get hot to produce good results.(you cant preheat silicon) so I use the first pour to just sit and heat up the mould then remelt the usually crappy first pour.
I will take a few photos tonight and post up tomorrow
A bad days fishing is better than a good day in the office

jurelometer

Quote from: Leerie18 on November 04, 2018, 11:58:20 AM

Sometimes the wire does not get covered with metal properly, or you have a problem where your wire is not hot enough and the metal does not flow nicely around the wire to fill the ends of the mould.
[/quote]

Your advice is spot-on thank you! Repeated pour failures earlier this morning exactly as described.
Will revisit throughwire set-up and start again. Silicone mould still in good shape, been using a fine pre-cast mould coating of talcum powder each time.

[/quote]

As others have noted, horizontal pours are tough on longer/thinner jigs.     Air pockets form at the ends, slowing the travel of the molten metal.   The wire also cools the molten metal before it can force the air out.  Vertical pours  work much better for me- no problems with cold wires.     I  also like to make a vent as well as a sprue,  so that the size of the opening where the sprue joins the mold can be smaller. Makes for less  trimming before painting. But a vent is not necessary if the opening is large enough to let all the air evacuate.




Quote from: Gadget on January 31, 2019, 05:30:40 AM
Have read everyones ideas I thought I'd post up what I do here in Western Australia. I've been making my own leadheads since the late 70's and in the last 10 years got into deep drop jigs,flat fall and flutter jigs all made at home from hand carved balsa masters. Originally I was able to get hold of Dow Corning RTV 5160 i think was its number. High temp resistant and  long lived .(those moulds are as good today as when I made them in the 70's) The silicone gurus over here tell me that the formulae have changed for silicones and the long lasting stuff doesnt exist any more. I now use a Product called Wacker 4670 made by Barnes Corp. Its a fawn colour(shore 60) and works well so far but apparently wont have the longevity of the Dow Corning stuff. If I'm making vertical jigs I make the mould casing out of 40mm,50mm or 60mm  white poly pipe.Seal off the bottom with Gaffer tape,suspend your master inside the pipe and then pour the silicon to the top. let it set and then using a hack saw cut a slot lengthwise down the pipe to release the mould with the master inside.Once the mould is out, cut right around with a stanley trimmer and extract your master blank.Then carefully carve a pour entry hole into the silicone mould (essentially you now have a round two part mould)Also cut a hole in the poly pipe in the same position plus a small vent hole at one end of the mould.
The you rig your wire put the two halve back together and slide back into the poly pipe.I then use a clamp to keep things together and pour the lead.
Getting the finished jig out requires gloves and I use a piece of large dowel to push the mould back out of the poly pipe.
I've made dozens so far and have not had a jig mould disintegrate yet and i'm using pure lead so they are wearing a fair bit of heat 700degrees plus .
Getting the lead real hot gives the best results and the mould itself needs to get hot to produce good results.(you cant preheat silicon) so I use the first pour to just sit and heat up the mould then remelt the usually crappy first pour.
I will take a few photos tonight and post up tomorrow
Post some photos!

I find that the size and depth of the cavity makes a big difference in how long the mold will last.   

Wacker makes a high temp RTV (300c degrees)  -  product number 4470.   I don't think that 4670 is rated for casting low-melt metals.  It might be worth giving 4470 a try if you can get your hands on the stuff.

-J


Gadget

I've used two .A salmon coloured one which will tolerate the heat but is a more flexible type of silicon and the beige one which I/m sure is 4670
you can see it in the attached photo plus the original Dow Corning stuff in red
A bad days fishing is better than a good day in the office