Alan in Vermont
02-16-2012, 04:12 PM
OK guys, here's the tip of the month.
Getting holes drilled as close to center as possible, in the base of boolits, so you can put a screw in them to lap a mold can be touchy.
I pulled out one of my woodworking tools for the job.
In woodworking, when mounting door hardware, if you don't get the pilot hole for the screw in the center of the countersink in the hardware the screw goes in crooked, stand proud on one side of the countersink, looks like butcher work etc.
The same problem arises in our trying to center drill a boolit. The closer to center we can get the hole the better it is to twirl the boolit in the mold to lap the cavity.
Bring on the Vix-Bit (http://vixbitsonline.com/)! The drill bit is centered in a spring loaded retracting locator. The point of the locator fits in the countersunk hole in a hinge or in our sprue plate. If you've got a drill press it gets dead easy, just set the depth you want to drill into the boolit and go at it. Using a hand drill you do need to try to keep the drill perpendicular to the mold and be VERY careful not to go too deep.
Only small hassle is that you can't drill very far into the lead before the bit plugs up. The cure for that is to drill a little, then work the lead out of the drill flutes. Lead is so soft that it doesn't come out in chips but "extrudes" into a lead wire that fills the flute and jams the bit in the tool body. Luckily mine only spun the bit on the retaining screw. It could have easily broken the bit.
They are a bit pricey to use for one mold, I already have three of them from back in my woodworking years.
Getting holes drilled as close to center as possible, in the base of boolits, so you can put a screw in them to lap a mold can be touchy.
I pulled out one of my woodworking tools for the job.
In woodworking, when mounting door hardware, if you don't get the pilot hole for the screw in the center of the countersink in the hardware the screw goes in crooked, stand proud on one side of the countersink, looks like butcher work etc.
The same problem arises in our trying to center drill a boolit. The closer to center we can get the hole the better it is to twirl the boolit in the mold to lap the cavity.
Bring on the Vix-Bit (http://vixbitsonline.com/)! The drill bit is centered in a spring loaded retracting locator. The point of the locator fits in the countersunk hole in a hinge or in our sprue plate. If you've got a drill press it gets dead easy, just set the depth you want to drill into the boolit and go at it. Using a hand drill you do need to try to keep the drill perpendicular to the mold and be VERY careful not to go too deep.
Only small hassle is that you can't drill very far into the lead before the bit plugs up. The cure for that is to drill a little, then work the lead out of the drill flutes. Lead is so soft that it doesn't come out in chips but "extrudes" into a lead wire that fills the flute and jams the bit in the tool body. Luckily mine only spun the bit on the retaining screw. It could have easily broken the bit.
They are a bit pricey to use for one mold, I already have three of them from back in my woodworking years.