Post by Bullshop on Mar 28, 2021 8:17:15 GMT -7
I want to share something that I guess I re-learned this week. Several decades ago when the diagram of my learning curve of casting bullets would have been little more than a scratch on the paper I was reading and digesting everything I could find on the subject of bullet casting. Somewhere I found that by coating the mold block top and sprue plate bottom with a simple graphite pencil that lead smearing and soldering to these parts could be prevented. In testing the information I found that it did indeed work but had limits.
This was of course before the advent of our Bullplate sprue plate lube which came about by progressive improvements over the simple graphite pencil. Our Bullplate is still the best I have found for keeping molds running smoothly while running hot and fast. Though it is a great product for lubing alignment pins and surfaces and sprue plate and mold block top it causes problems when used directly in the cavity.
It can help with bullets sticking in the cavity but with each application in the cavity there is quite a long burn off time where castings are poor due to voids created by burn off gases being produced faster than they can be vented out. Also when casting fast and hot as I do or even not so fast and hot but using tin rich alloy there can be a soldering effect on a micro level taking place at the near right angles of the junctures between lube grooves and drive bands in the cavity. This can create an annoying situation where the bullets must be coaxed from the mold not falling out of their own weight.
The problem is visible with a good magnifier and can be seen as just the faintest particles of alloy adhering to the very corners of these junctures. In effect when this is happening each casting in a cavity so effected is bonding to this small amount of alloy that has been soldered to the cavity and each casting will not release from the cavity without that small section being torn off. Each casting in this case will have a visible void at the sticking location at the very edge corner of the drive band. This can be small and nearly imperceptible unless viewed with a magnifier but its effect can be hugely annoying.
Now the good part. I asked Tina to get me some extra hard pencils and she did by supplying me with a box of I believe #4 hard. These sharpened to a sharp point can get into those potential trouble spots in the cavity to not only remove anything stuck there while the mold is hot but also as a preventative coating to prevent the issue from re occurring.
Here I will give a good example of the effectiveness of a preventative coating. I have a vintage Cramer mold for a copy of the 45 Colt arsenal mold for the 255gn hollow base bullet. I am normally able to run at between 3 to 4 cast per minute with this mold without any mold prep other than bullplate on the sprue plate bottom and mold block top. Three to four per minute is good enough to keep the block hot enough to cast well but just barely. The normal rhythm is like this, pour, cut sprue, open blocks, press base pin through mold block with gloved thump, and finally a couple light taps on the hinge of the inverted mold and the bullet drops out. Thats not bad and produces about 30 to 40 bullets in every ten minutes.
Now buy coating everything with the #4 hard pencil everything including the internals of the cavity, the base pin and it alignment as well as its connecting pin going through the block the pace picks up to six casts per minute producing 60 bullets for every ten minute time investment. This big difference is possible because all I now need do is to open the blocks and invert the mold and the bullet drops out of its own weight. The thumb push on the base pin and the time required to pick op the mold mallet and tap the hinge is eliminated thus allowing a higher cyclic rate.
Not only does this simple #4 hard pencil trick allow production of a greater number of quality castings in the same amount of time but the pleasure level is increased many times over. Trust me when I say that working with any mold that drops its castings so effortlessly is a joy to use.
So it looks like along with our Bullplate sprue plate lube #4 hard pencils with a good sharpener that easily produces a very sharp point will all be regular items in my casting routine from now on.
This was of course before the advent of our Bullplate sprue plate lube which came about by progressive improvements over the simple graphite pencil. Our Bullplate is still the best I have found for keeping molds running smoothly while running hot and fast. Though it is a great product for lubing alignment pins and surfaces and sprue plate and mold block top it causes problems when used directly in the cavity.
It can help with bullets sticking in the cavity but with each application in the cavity there is quite a long burn off time where castings are poor due to voids created by burn off gases being produced faster than they can be vented out. Also when casting fast and hot as I do or even not so fast and hot but using tin rich alloy there can be a soldering effect on a micro level taking place at the near right angles of the junctures between lube grooves and drive bands in the cavity. This can create an annoying situation where the bullets must be coaxed from the mold not falling out of their own weight.
The problem is visible with a good magnifier and can be seen as just the faintest particles of alloy adhering to the very corners of these junctures. In effect when this is happening each casting in a cavity so effected is bonding to this small amount of alloy that has been soldered to the cavity and each casting will not release from the cavity without that small section being torn off. Each casting in this case will have a visible void at the sticking location at the very edge corner of the drive band. This can be small and nearly imperceptible unless viewed with a magnifier but its effect can be hugely annoying.
Now the good part. I asked Tina to get me some extra hard pencils and she did by supplying me with a box of I believe #4 hard. These sharpened to a sharp point can get into those potential trouble spots in the cavity to not only remove anything stuck there while the mold is hot but also as a preventative coating to prevent the issue from re occurring.
Here I will give a good example of the effectiveness of a preventative coating. I have a vintage Cramer mold for a copy of the 45 Colt arsenal mold for the 255gn hollow base bullet. I am normally able to run at between 3 to 4 cast per minute with this mold without any mold prep other than bullplate on the sprue plate bottom and mold block top. Three to four per minute is good enough to keep the block hot enough to cast well but just barely. The normal rhythm is like this, pour, cut sprue, open blocks, press base pin through mold block with gloved thump, and finally a couple light taps on the hinge of the inverted mold and the bullet drops out. Thats not bad and produces about 30 to 40 bullets in every ten minutes.
Now buy coating everything with the #4 hard pencil everything including the internals of the cavity, the base pin and it alignment as well as its connecting pin going through the block the pace picks up to six casts per minute producing 60 bullets for every ten minute time investment. This big difference is possible because all I now need do is to open the blocks and invert the mold and the bullet drops out of its own weight. The thumb push on the base pin and the time required to pick op the mold mallet and tap the hinge is eliminated thus allowing a higher cyclic rate.
Not only does this simple #4 hard pencil trick allow production of a greater number of quality castings in the same amount of time but the pleasure level is increased many times over. Trust me when I say that working with any mold that drops its castings so effortlessly is a joy to use.
So it looks like along with our Bullplate sprue plate lube #4 hard pencils with a good sharpener that easily produces a very sharp point will all be regular items in my casting routine from now on.
