Starting a mold

[wtfooptimax200]

What steps do you take to prep your new mold for its first casting session? Are there any material specific steps that must be taken for the various mold materials?

[deltaenterprizes]

A good cleaning is a good first step.

[onondaga]

A good cleaning is a good place to start. You may notice debate here on what to clean with.

I recommend not using solvents with any type of petroleum or petroleum distillates. The oils will gas out with heat and cause craters and wrinkles casting.

Clean with a good detergent like Dawn dish-washing liquid and very hot or boiling water. Hot rinse and dry.This will remove machining oil from the manufacturer.

Next I use a Silicone Grease or silicone oil ( dielectric grease from a car parts store is good) Then I disassemble the sprue plate and lube the threads of the pivot pin lightly. Use a Q-tip and only apply a very light rubbed out shine to the mold block locating pins and the block tops and plate bottom. Just a shine, this is very easily overdone and any lube over-applied will cause casting problems. Just a rubbed out shine! Not wet.


Gary

[JIMinPHX]

First I clean it. Then I check for burrs. Then I check the sprue plate tension. Then I lube the mold. Then I try casting with it & see how it does.

My first lube is a mixture of hi-temp grease & never seize. I use that as a cold start up lube on the first cast only. I'm especially careful to get some under the sprue plate & around the sprue plate pivot. Once the mold is hot enough to properly apply Bullplate for the first time, I switch over to that & stick with it for the life of the mold.

On some molds, I wipe the cavities with kroil while the mold is cold & then wipe it dry before casting. On some molds, that helps the boolits drop out better.

I recently read how some people use alcohol as a carrier for powdered graphite & lube the cold mold cavities with that. I haven't tried that yet myself, but I may. It sounds like it might be a good idea.

[wtfooptimax200]

What is done if burrs are found in the mold? How are they removed?

[onondaga]

I remove aluminum mold cavity edge burrs with a Popsicle stick. use it like a knife or scraper. Metal tools on an aluminum mold will quickly damage the mold unless you have hand skills like a great eye surgeon.

Very small burrs on an aluminum mold cavity edge can also be removed by scrubbing with Comet cleanser and a tooth brush.

Burrs on a steel or iron mold are something I work on with a rubber abrasive point in a dremel tool. I don't use stones or diamond or metal points as it is too easy to damage a mold and the rubber points work fine and do the job gently and leave a shine.

Your sprue plate has the funnel gate holes bent and protruding on the plate bottom. I fix that with an extra fine Arkansas Oil stone and hone with oil by hand to flatten out the protruding edge.

Gary