Sinker mould making for beginners

coolwings

Many beginner anglers ask about making their own fishing sinkers at some time or other.

It involves making a mould like this.


The method is get a box, Grease the bottom and sides with cooking oil or vaseline.

Half fill the box with plaster of paris, grease the sinker and press down until half sunk in the plaster.
Then when it is half set (15 - 30 minutes), push 4 nails into each corner pointy-end down, until halfway into the plaster.
When all is hard, grease the top of the sinker again, and also the surface of the plaster that it sits in. Do not let any grease get onto the nails.
Next fill the box up to the top with plaster of paris. Leave to set.

When hard either disassemble the box or remove the cube of hardened plaster carefully.
use a knife inserted into the "grease-line" to prise the top off the bottom of your mould.

Next remove the sinker carefully, and using a sharp tool scoop out the funnel shape filler sprue-hole. Half of it in the top and the other half in the base of the mould.
Also cut a fine line out to the other side to allow air to bleed out as the hot lead, resin or whatever goes in through the funnel.

This should work for you. But you should know that plaster is a crumbly brittle mould material. I changed over to fibreglass and silicone a long time ago due to moulds cracking after only one or two uses. I get my casting glass and silicone and 6mm chopped fibreglass at Green Hobby & Model . Previously I used to get my plaster at the local pharmacy who were very helpful in getting me started in casting.

A partial "fix" for the flaky quality of the plaster is to add fibres in some form. Wrapping cloth around the insides of the box before pouring the plaster in, will produce a tougher outside to your mould later on. Stirring in some of the 6mm chopped fibreglass strands into the wet plaster adds a lot of strength, far more than you would think. Stirring the 6mm strands in is well worth doing after you have done your first "dummy run" experiments and are working on your first proper mould.

Before pouring lead the two halves of the mould should be firmly clamped together so a pressure of expanding hot air inside will not force them apart and spill hot liquid lead. If you do not have a bench vise "C" clamps are a substitute, and leather straps a poorer substitute.

No moisture can be permittedmto get near the hot lead, as it turns instantly to steam, and can cause hot lead to "splatter" like the hot droplets of water from a kettle boiling. So beware of adding flattened lead pipe to your hot steel saucepan or pot, there could be water trapped in the flattened sections.
It would be ok to perforate with a hammer and nail, then heat such items slowly to hot, but not to add them to already heated lead.
Also, stand back to pour, and never pour with a part of yourself under the pouring area.
The normal safety requirements for extreme heated items are prudent.
Research them before trying the hot pouring. eg Experienced moulders might wear a leather apron to sagfeguard against accidental splashes.

If you are in doubt about using hot lead there is a "cold moulding" technique you can try.
Cold thinned epoxy resin with small lead shot stirred in to get the weight is poured into a mould with an enlarged sprue-pouring hole. This works better than many imagine. I have made downrigger cannonballs with vanes this way.

stevecrow74

one thing when melting lead of any kind to make weights...


Molten lead when heated produces toxic gas that can cause brain damage. It's therefore vital that you work in a well ventilated area when melting this metal.

ButcherOfNog

And don't spill any molten metal on yourself, it's not pleasant.

Degsy

Make sure not to pour the lead into anything thats wet,the water will vapourise the liquid lead,spraying it in all directions.

Degsy

Another way to make lead weights is very easy.Simply get copper pipe,say half inch in diameter and cut into the desired lengths..longer for heavier weights etc..its easy enough to judge.Sit the length of pipe into a bed of sand to seal the bottom.Hang a swivel into the neck of the pipe to attcah your line to and then pour in the lead.If you havnt got a swivel,simply bend a piece of tjick wire into a loop and insert that in the pipe.