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Thread: bullet appearance after lapping lee mold

  1. #1
    Boolit Buddy
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    bullet appearance after lapping lee mold

    I have cast a few times with my Lee 6 cavity 200 grain H&G clone. It seemed like a couple cavities stuck pretty bad. I tried to lap the mold tonight. I wanted to post before banging my head against the wall too much.

    With my initial casts, I was able to produce some good bullets, after culling them. I had a few issues but I won't get into them. To prepare the mold, I cleaned it with alcohol to remove the grease from manufacture. I lubricated the sprue plate, the bolts, and the alignment pins using anti seize. Like I said, I was able to cast decent bullets after this but some would stick a fair amount. I wanted to avoid having to whack my mold (at the bolt between the handles) 3-4 times to drop the bullets. Even using a mallet it seemed I had to hit the mold harder and more times than I should need to.

    I lapped my mold using bolts rather than screws. I poured the lead through the bolts into the cavities rather than through the sprue plate. I then made a paste with Comet and water. I applied this paste to the bullets using a q-tip. I turned the bullets in the mold about 20 times for the problem cavities. I gave the good cavities a couple turns as well. I am wondering if I did something wrong here. I thought Comet wouldn't be so abrasive but now that I'm done I have some circular marks on my bullets. I am wondering if the paste was too thick.

    I rinsed the comet out of the mold using tap water, and cleaned the cavities as best I could using a fresh q-tip. I did not smoke the mold again after I cleaned the cavities. I feel like this is a dumb question, but should I smoke it again? I tried to search for this but came up short.

    Should I clean the mold again using alcohol? I thought that comet being a cleaner, it would rinse off well enough.

    Could the issue be temperature related? My alloy wasn't pouring particularly fast. I was casting with my pot turned down a bit in comparison to my previous attempts.


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  2. #2
    Boolit Master 44Blam's Avatar
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    Looking at the boolits, it looks like you do not have good fill out. The bases are not sharp...
    Maybe you need a little tin in your alloy and a little warmer cast temp?

  3. #3
    Boolit Buddy
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    does the mold need to be smoked again after it's lapped? could it also be related to the mold not being clean enough?

    I did just inspect a sample from that batch. It does look like some of the bullets had similar signs as before when my alloy wasn't hot enough.

    I am using range lead so I don't really know what's in it. I have had success but I think I had to cast with my alloy at a fairly hot temperature. I decided to start with what I have and see what I would get rather than add tin right away.

  4. #4
    Boolit Buddy
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    For comparison purposes, here is a pic of some good ones from a previous batch. I believe these have a beveled base. This was before I lapped the mold.

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    Last edited by weeple2000; 12-06-2018 at 01:57 AM.

  5. #5
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    Those grooves look pretty big for Comet. Maybe a grain of sand or a metal impurity got in.

    Did you do all the cavities? See if you can see any pattern. I’ve heard of people using toothpaste, but don’t know if it still has the same stuff in it as before. Automotive polishing compound works and you are sure of what you are getting. I think most of those can be polished out. Make sure you do exactly the same thing to each cavity so all your boolits will be the same.

    Just the way I do things. I only use a tiny bit of beeswax for my sprue plate when I think I need it. Any oils or greese in a cavity will drive you crazy. I clean my molds with automotive break cleaner. You can normally find it pretty cheap and with force it comes out, I think I use less. When I’m done. I spray with Ballistol. Last, I never smoke my molds. I just keep casting and until things come together.

    I’m sure a lot of people do things differently. Good luck

  6. #6
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    Those ones with the lines looks like a cold mold. All the edges look rounded aswell. Even the lube grooves dont look filled out. Up the alloy temp and run the mold hotter or preheat the mold. Adding tin hasnt fixed things for me. Uping the alloy temp a couple hundred degrees has fixed a lot of issues when i cast.

    Those comparison bullets in the second picture look good. Let the sprue cool bit longer so you dont crater the base.

    I have had to smoke molds for a couple cast. Eventually the molds break in or season and dont need to do it anymore. I like antiseize on my sprue plate and 2 cycle oil or beeswax on the hinges.
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  7. #7
    Boolit Master
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    The only reason to smoke a mold is to help it drop the casts easier. The pictures you posted indicate a mold and pot not up to temperature. If your not pouring with a good flow of lead, that is not good. A six cavity mold from Lee is the hardest for me to get up to temperature. What I do now is cast only the far two cavities until I get decent casts. Then I add the third cavity until all three throw good casts then the fourth and so on and so on until all six cavities are throwing good casts. You can also place the mold on a hot plate to get it warmed up before starting to cast. What was your lead temperature? You do use a thermometer right? If not then you are casting blind in my opinion.

    Smoking your mold has nothing to do with your problem.
    Last edited by Gohon; 12-06-2018 at 02:19 AM.

  8. #8
    Boolit Buddy
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    I went through the sample I had and it seemed like there was at least one example bullet that didn't have the grooves. I am wondering if the issue is fill. I am going to try to clean the mold with alcohol again and smoke it again.

  9. #9
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    Actually I think you're right that my mold temperature is probably the issue. The alloy probably has to be hotter too. I have been using a hotplate to preheat my mold. I cast my bolt bullets for lapping, then I let my mold cool. So after I was done lapping it and rinsing it, I put it on my hotplate. I think the alloy didn't have to warm up as much when I turned it back on to start casting, so my mold wasn't on the hotplate as long.

  10. #10
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    Based upon the pics, I would have to say a cold mould, low melt temp. and possibly a slower pour caused the poor fillout.

    The ones in the second pic are looking good, so try to repeat what you did with those.
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  11. #11
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    Hotter both mould and alloy

  12. #12
    Boolit Master
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    If I have need to polish an aluminium mould I use toothpaste as the abrasive as this gives a fine polish, I do find that it takes a little casting to get the mould operating properly after lapping. I also thing more heat will fix your problems. Regards Stephen.

  13. #13
    Boolit Master daloper's Avatar
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    As others said. Mold and melt temp needs to be raised. Also increase the pour rate. You may be pouring to slow and that will cause those lines just like a cold mold.

  14. #14
    Boolit Master 243winxb's Avatar
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    The before and after photos show a screwed up mold from using Comet.

    The orginal problem could have been solved with more heat in mold and alloy. Hotter causes more shrinkage of the bullet as it cools. The shrinkage lets the bullet fall free.

    And yes, most moulds need to be hit with something.

    Lee-
    Mold lapping
    Posted by on 11 April 2012 01:17 PM
    Remove the core pin assembly and sprue plate, and block off the sprue hole in the top of the mold. Lightly clamp the mold in a vise, base up. Suspend a 1/4" or 5/16" tap into the center of the mold, and fill with molten lead. When the lead solidifies, you should have a polishing mandrel that fits the inner diameter of the mold fairly closely. Don't worry if there are wrinkles, the mandrel doesn't have to be perfect. Coat the mandrel with valve lapping compound or Clover compound, or something similar, and using the embedded tap, give it a couple turns.
    More from LEE-
    this is the casting procedure that I recommend: 1) Pour 2) Turn the mold past vertical and knock the sprue into the pot 3) Turn the mold upside down, open and knock the handles to release the bullets.... never into the pot though. With the sprue plate straight out to the right, you can knock the handle just above the sprue plate. 4) Close the mold 5) Turn the mold right side up and only then, close the sprue plate.
    http://leeprecision.net/support/inde...roduct-support

  15. #15
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    Your lapping was so gentle I very much doubt you messed up the mold.

    I agree with Rcmaverick and others that the post lap pic shows cold mold casts.

    While bringing up the temps will fix the appearance issue, it may not help the sticking issue. Besides lapping, examine the cavities under magnification for burrs, and use a qtip and see if it snags any cotton.

    New Lee Aluminum molds do require a little break-in, until the aluminum is oxidized. That's what the smoke is for, to get past that stage. When lapped they require break-in again. One casting session usually does it for me.
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  16. #16
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    I run a dozen Lee aluminum molds and have never smoked them. Get you pot and mold temp up and an aluminum mold will cast just fine right out of the box. Well after you clean the oil off the new mold first. Haven't found a mold yet that didn't need a rap on the handle bolt to get a bullet to fall free now and then, if you hammering the heck out of the mold to get the bullets out its another indication that your not up to temp.

    When I started casting 10 years ago the wives tale about smoking molds was going strong and most guys on this board we against it but I see smoking molds just won't die out.

  17. #17
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    It seems you need to preheat your mold more + raise your alloy temperature as well to get good fill out . I seriously doubt you damaged your mold with the comet / water paste . I would give it another good scrubbing with a old toothbrush + warm water + dish liquid . After you start getting good fill out you can then try to find the sweet spot where the boollits drop out of the mold .

  18. #18
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    JonB_in_Glencoe's Avatar
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    yep, you need more heat. Do you have a thermometer in your alloy?
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  19. #19
    Boolit Buddy
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    I don't have a thermometer. I am thinking I might just build a PID.

  20. #20
    Boolit Master
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    The before and after photos show a screwed up mold from using Comet.
    No...the photos show no such thing. I've used Comet to polish two maybe three different Lee molds and I was a lot more aggressive than the OP. If the Comet had of cut those rings into the mold cavity the finished product (Cast) would not have depressed rings around the cast but would have ridges circling the cast. The OP's problem in my opinion is lack of heat.

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