Need advice about casting technique

[EDG]

I have a had a lot of frustration with getting molds to work right.
My current beef is with a very high quality mold for a 510 grain government style 45-70 bullet.
I am not mentioning the brand of mold because I don't think my issues have anything to do with the mold other than the blocks are large and are hard to heat up.

My alloy is double melted and cleaned wheel weights with 1% tin added. The tin was added using a program that calculates the proper percentage of the 60/40 solder that I have.
The hardness is about 12 Brinnell as checked with my LBT tester. My LBT tester is pretty close to the hardness values given for 60/40 solder. I have heated the alloy to 775°F and to 800°F with the same results. The bullets are poured with an RCBS dipper using the pressure method. That is I turn the mold sideways, apply the dipper and turn both up right using the weight of the alloy in the dipper to force the metal into the mold.

The results are:
1. The mold is very slow to heat up and I get poor fill even after 40 or 50 bullets. Even then I get a smiley face wrinkle on the nose most of the time. If I cast 100 to 125 bullets I might get 25 that are free of major defects. The rest are wrinkled and poorly filled out.
2. Even the filled out bullets may have a 1/4" long patch of frosting that extends half way around the bullets.
3. I can't say that I have ever cast one single perfect looking bullet from this mold.

The mold just wears me out to use it. I do all that work for so few bullets yet the few semi-decent culls that I use are very accurate in several different rifles. I have no beef with the performance of the bullets and feel like this mold would produce astounding accuracy with well cast bullets. The problem is I cannot get it to cast anything that is not ugly.

[IcerUSA]

I would pre heat the mould , get a cheapie hot plate form your locale Super Mart and pre heat that big sucker and cast away , if it gets cooled down , back on the hot plate .

Works for me with any mould I have so far , even too warm sometimes . LOL

Keith

PS I start my casting session by turning on the hot plate and pouring pot at the same time , when the lead is to temp so is the mould , I get good results from the get go .

[Vly]

I would think your problem could be one of two things. First, is the mould clean? Have you done the boiling water/soap cleaning technique?

If you are convinced the mould is clean, then I would look at air venting. If you are using the pressure technique the air may not be able to escape quickly enough. Make sure all the vent lines are open. Maybe try the bevel on the top edge trick to let the air out faster.

Those are my thoughts.

[imashooter2]

Lots of things to try.... You can pour the lead without dipper contact. Pour it straight into the sprue plate hole. Swirl it in off the edge of the sprue plate countersink. Heat the melt even higher. Preheat the mold on a hot plate or the edge of the melt pot. Vary your technique until you find what works.

[docone31]

It sounds like it is a cold mold when casting.
If it is aluminum, it needs heat. You can tell when it is too hot, the sprues drag. You just slow down the casting. If it is aluminum, You can also cast through a nut, removeing the entire casting when cold. I add lapping compound and spin it slowly in the mold, polishing the cavity.
I do not know much about iron, as I do not use them.
It does sound like the mold is too cool.

[Southern Man]

The mold should be plenty hot no matter how big it is , after casting that many , with alloy that hot.
The frosting is saying it's to hot.
The problem almost has to be poor venting.
The mold not clean ,or both.
If your using a mold prep , that can cause poor venting.

[EDG]

Guys,
Thanks for the comments.
This is a mold that would cost nearly $200 to duplicate.The mold is steel and it is new less the couple hundred attempts I have made. I cleaned it with brake cleaner and compressed air. The venting looks good but not really overly generous. Your comments reminded me of one other ugly thing about it. The bullet always sticks in the same side of the mold until it gets to the point of almost producing good bullets. Then it starts sticking in the other side!!! The 3rd ugly thing is the sprue plate has some ugly rings in the sprue hole countersink typical of a countersink that has been ran too fast dry and had steel stuck to the cutting edges.
These rings sometimes cause the sprue to stick in the countersink. Other than this it is a beautifully made mold and I can really find no fault with it even with a magnifying glass. The maker is a well known BPCR shooter and I can't imagine that there is really anything significantly wrong with the mold.
For sure it will not cost anything to run the metal even hotter and preheat the mold.

[454PB]

Big cavity moulds like that usually want to run too hot, so it sounds like either a venting problem or contamination. My first efforts would be to clean up the tooling marks on the sprue plate, then when it is reinstalled, leave it slightly loose. If you get some "flashing" or fins on the boolit base, then tighten it slightly. If it takes more than light pressure to close the sprue plate, it's too tight.

[grouch]

It sound to me like it's the first run with a new mold - in any case oil in the cavities. If that's the problem, it'll get better next session. Also, you can try smoking the inside of the cavities with a match or butane lighter, especially the sticky side. That may speed up the break - in.
Good luck. Grouch

[e15cap]

Try rubbing a lead pencil over the sprue plate top and bottom, and in the sprue holes, the graphite will help the sprue release.I pre-heat molds on a gas stove for two min 15 sec on each side before casting. Try rubbing your finger along the mold cavities and feel for burrs and look at the edges of the cavity with magnification. Cherries used to cut the cavities will leave burrs and bullets will hang on them. Lay a small Swiss file flat on the mold block and push it flat along the side of the cavity with your finger tip. You can feel the burrs, just do this till it smooths up. Check the pin alignment holes as the will get burrs too.
Your mold needs to be hot enough that the puddle on top is liquid to feed the bullet as it cools and it will wink at you as it hardens. Wait a touch to harden the sprue and then cut it off. I also clean before pre heating each cavity with acetone or laquer thinner.
Hope this helps, Roger

[Doc Highwall]

Another thing to check is the size of the hole in the dipper, if it is to small it will not let the alloy flow fast enough into the mould.

[montana_charlie]

Once you get that beefy mould well-heated, it should stay hot. You may even need to cast rather slowly, so it doesn't run too hot.

You say you have been using the 'pressure method' and getting disappointing results.
It's time to try a different method.

Mate the dipper to the sprue plate to prevent spillage as you turn the mould upright, but maintain only light contact. Hold that for a short moment, then tilt the dipper to finish filling the cavity...using dipper angle (instead of sprue plate contact) to prevent spillage until the cavity is full. As the sprue starts to build up, let most of the rest of the dipper contents flow off the side of the mould, and back into the pot.

By not keeping the dipper and sprue plate 'welded together', you allow things to move as needed to vent air as the cavity fills...and the main advantage of that is - the sprue plate is not 'glued' to the top of the mould by pressure from your dipper.

If your mould/alloy temperature combination is high enough so the sprue takes more than three seconds to solidify, your metal should be staying liquid long enough to fill the cavity well.

If you still get wrinkles, see if they always appear in the same part of the bullet. If so, clean the mould...then clean it again...and maybe even once more. The only mould that really tried to make me insane just needed 'another cleaning'.

Here is a video of a guy dipper casting big bullets...and doing a fine job. Notice how much 'foolin' around time' he has in his rythmn...
http://s17.photobucket.com/albums/b67/Sharps110/BPCR%20SHOOTING%20RELOADING/?action=view&current=CastingGoodBullets.flv

CM

[e15cap]

What Charlie said and do NOT press the dipper hard onto the sprue plate. That thing needs to move and allow air to vent when the metal goes in. Roll the dipper just a touch to fill the cavity and let excess flow off into the pot.
Best Roger

[EDG]

Thanks again guys
Sounds like my technique need a lot of work. I have really been mashing the dipper hard against the sprue plate. So I will clean it again and try it again. My sprue plate is loose - maybe .002 clearance at the screw. When I lift on the sprue plate the edge of the mold block most distant from the sprue plate retaining screw has about .010 clearance. My dipper may need to be drilled out but the sprue plate looks like the limiting diameter at .125. BTW the wrinkle on the nose is a smiley face about 45° off of the tip and is always located on the side of the bullet that comes from the mold block that is up before I tilt the mold up when pouring. I am right handed and hold the mould handles in my left hand so the smiley face is coming out of the left block.

[chrisx1]

With the wrinkles always being in the same spot points to a dirty mold. I am with Charlie, the mold that caused me more problems than any other just needed cleaned one more time.

I use brake cleaner too. Use a Q-tip or something to get in there in every crevice. An old toothbrush works good too. I have even heard of guys boiling them. Smoking the cavities will help with condensation also.

Chris

[imashooter2]

There is no cleaner mold than one that has been boiled in soapy water, period.

[Wayne Smith]

You have described everything except your alloy. A slightly zinc contaminated alloy will do many of the things you are describing.

[Tom Herman]

Folks here have a lot of accumulated knowledge!
Although I mostly cast for large bore revolver, here is my take:

-I would use 2%Tin for better mold fillout.
-Smoke the mold. I use Frankford Arsenal dropout on my revolver molds.
-Re-clean the mold. I've had new molds with less than 200 pours sometimes give me fits as oils continue to come to the surface.

And yes, I now preheat my molds on an electric stove set to 2 or 3... It makes a BIG difference in initial casting! I can sometimes go straight into making bullets, or only needing a couple of pours before I get good results.
Good Luck!

Happy Shootin'! -Tom

[Tom Herman]

And that's the guy dropping pieces of lead back into the pot without refluxing. That would be a no-no for me... Otherwise, an excellent job...
Thanks for sharing!

Happy Shootin'! -Tom




Here is a video of a guy dipper casting big bullets...and doing a fine job. Notice how 'foolin' around time' he has in his rythmn...
http://s17.photobucket.com/albums/b67/Sharps110/BPCR%20SHOOTING%20RELOADING/?action=view&current=CastingGoodBullets.flv

CM

[sundog]

If the sprue hole is too small, open it one drill size at a time, that is only one size larger than the largest that will fit. No more than that. Hand chamfer the hole and stone the under side to remove any burrs. Cast again. Improper sprue hole size can produce some frustrating casting sessions.

Also, if the mold is clean, try the pencil trick. Color the cavities completely, and the block top and under side of sprue plate.

[Cap'n Morgan]

Try clamping a bit of paper between the mold halves when casting. This will guarantee adequate venting and indicate if this is your problem.

[montana_charlie]

There is no cleaner mold than one that has been boiled in soapy water, period.
If a mould is cleaned 'all the way', there is no cleaner mould. From that point on, it doesn't matter much how you got it there.
But the mould (I mentioned) that tried to put me in the funny farm got cleaned in an ultrasonic cleaner with a 2% solution of Micro 90. THAT made a surface so bare of contaminates I had to work quickly to prevent 'flash rust'.

I was dinking around on the Midway site and came across a link to Lyman's mould instructions.
http://www.midwayusa.com/midwayusa/StaticPages/pdf/instructions/Bullet_Making_Guide_All_Molds.pdf

It mentions (early in the document) about how you need to clean a mould BEFORE you ever heat it up.
It says that 'vaporised' oil will leave a 'baked on' residue.
That is the kind which can drive you nuts.

So, if you tried casting with a mould that you thought was clean...but it wasn't...you can end up with that 'residue' which is a devil to find and remove.

CM

[EDG]

Montana Charlie,
I was not the first owner of this mould. It looked like it might have been used to test cast 2 or 3 bullets because the bottom of the sprue plate was still new and the tops of the blocks were still heat blued. However it did appear to have some cooked on oil or grease stains that brake cleaner did not remove. Sounds like I need to scrub it with acetone. That's going to be fun.

[imashooter2]

If a mould is cleaned 'all the way', there is no cleaner mould. From that point on, it doesn't matter much how you got it there.
But the mould (I mentioned) that tried to put me in the funny farm got cleaned in an ultrasonic cleaner with a 2% solution of Micro 90. THAT made a surface so bare of contaminates I had to work quickly to prevent 'flash rust'.


If you had boiled it in soapy water, you would have removed contaminants from below the surface that leach out when you heat the mold to cast. It's not just the soapy water, it's the heat from the boil.

Newer isn't always better.:-D