New Lee mold oddity

[pcarpenter]

I just finally gave in and decided to cast for 9mm and 40S&W after avoiding it forever due to the usual cautions about it being more difficult than working with lower pressure rounds. I figured since I now cast for several old millitary cartridges in additon to all the revolver cartridges I shoot, plus .45 ACP, I may have passed the point in the learning curve where I should not let this issue slow me down. I read a good bit here and I know about the importance of fit, and proper case mouth expansion etc. so figured I'd give it a go, starting with a couple of Lee 6 cavity molds.

Both arrived with what I thought was pretty amazing fit and finish (look at those nice shiny cavities) for an inexpensive mold but both also had an issue that looks really odd to me. I've only cleaned up the burrs on the cavities and scrubbed the molds but did not yet have a chance to cast with them. The oddity is that there are three passes across the mold faces with a mill and the one in the middle clearly is deeper than the other two. It felt like maybe a thou or two and while it was tough to measure properly due to the position, it mic'd out at about .0015" or so. That adds up to .003" gap or so when the two are put together. I looked into the cavities with the mold halves together, using magnification, and I am afraid I am going to look forward to feathered bullets. Could this be to allow for perhaps greater expansion near the center of the mold (because the mold is thinner there due to the grooves for the handle jaws and will become hotter in that area)? Or....is this an odd method of venting...or just a mistake? In the past, with other molds where I maybe had a lead booger on a mold face, a gap like that could end up accounting for feathering.

I have another Lee 6-cavity somewhere and I need to hunt it up to see what it looks like. I appreciate any wisdom the group can offer!
Paul

http://i108.photobucket.com/albums/n16/pfcarpenter/Handloading/2013-01-29_22-04-42_76.jpg

[Casting_40S&W]

I am familiar with plastic injection molding dies/molds, and that is standard practice for venting plastic injection molds. If the total is .003" I am certain it will not fin, as plastic injection molding operate at pressures as high as 10,000 PSI and do not flash. Our molds cost tens of thousands of dollars, pretty impressive if I must say, for a $53 dollar mold.

[jabilli]

Nice 'N Shiny! I've got a Lee 6 Cavity for 9mm as well...Love it.

I'd say the absolute best way to find out is to plop out some bullets and inspect...But from the fact that you havn't done so already I'm guessing that you might be wanting to return them. IIRC from random posts I've read Lee's customer service dept is pretty awesome. (They probably understand very well that casters pretty much depend on talking to each other and they figure it a bad idea to have folks unhappy with them.)

If this helps at all, here's a picture of a Lee .357 mold I bought some time ago. (Yeah I know I know...I wish I had a girlfriend that dirty :-p)

59900

I'm still unsure of this but I'm I'm reasonably certain the mold was botched- The ridged texture, I'm referring to (Someone please confirm this is not how the mold is supposed to be?). I cast up a batch or two of these guys and they shoot great.

With that- I think you're just fine. :-)

[jabilli]

Also,

Glad ya decided to try cast 9mm- It's the round I shoot most and I'm very happy with my results (guns most fired with my 9mm- Beretta 92 and Beretta CX-4 Carbine). I've never even purchased 9mm bullets :-p

[Moonie]

Nice 'N Shiny! I've got a Lee 6 Cavity for 9mm as well...Love it.

I'd say the absolute best way to find out is to plop out some bullets and inspect...But from the fact that you havn't done so already I'm guessing that you might be wanting to return them. IIRC from random posts I've read Lee's customer service dept is pretty awesome. (They probably understand very well that casters pretty much depend on talking to each other and they figure it a bad idea to have folks unhappy with them.)

If this helps at all, here's a picture of a Lee .357 mold I bought some time ago. (Yeah I know I know...I wish I had a girlfriend that dirty :-p)

59900

I'm still unsure of this but I'm I'm reasonably certain the mold was botched- The ridged texture, I'm referring to (Someone please confirm this is not how the mold is supposed to be?). I cast up a batch or two of these guys and they shoot great.

With that- I think you're just fine. :-)

That is some serious chatter marks, no shouldn't look like that, but if it shoots well who am I to argue. Let professor gun be the final arbitrator.

[pcarpenter]

Yeah...I have a few single cavity Lee molds too and some have a good bit of chatter. One, a .429 310gr bullet had some pretty serious chatter like that too, but it too shot fine. I ended up lapping the cavities a bit, but I don't think it made any difference in how the bullets shot. I was mostly after just a bit more diameter in that case. I sort of came to expect that any mold they claim is lathe bored might look a bit like that. They must use a boring bar of some sort and given the ratio of reach to boring bar diameter needed for a cavity that deep and small (diameter), chatter would seem likely. I guess that's why I was so impressed with the quality of the cavities in these last two molds. The aluminum extrusions they use for the 6 cavity molds seem to be a pretty soft alloy or at least at a fairly soft temper so I am surprised they machine as well as they do.

I think a lot of extrusions are made from like 6061-t3 and that tends to machine like bubble gum. I'm no machinist by trade-- I just play one at home. Don't know what Lee uses for sure, but these look good given how soft the material seems to be. Just need to exercise some care to keep them that way. I deburred the through holes they pressed the locator "bullets" into, so that the gobby burrs in the groove where the handle mounts don't hit the jaws of the handles. The stuff seemed soft as I cleaned them up with a burr in the Dremel tool.

Thanks for the information on the construction of injection molding dies. That's quite reassuring. I hope to have some time tonight to put the molds back together and see what I can make. I've got my fingers crossed that the 9mm mold will go clear to .358 as that's about where I intend to size them.

Paul

[truckjohn]

Personally - I would cast with them before doing anything else...

Remember that the mold has to be vented to allow air to escape during the cast.... and little fins are a whole lot better than voids in your castings.....

The only issue you could potentially run into is if you decide to "Pressure pour" - where you stuff the spout of your bottom pour pot into the sprue and open it wide.....

Thanks

[Pete P]

I would definitely use the mold see how it casts. It's hard for me to tell from the picture. But as one who has spent time on a milling machine, I would say, since three separate passes were made on the surface of the mold it's possible that the milling machines head was not square or the workpiece was not square on the first or second pass where the cavities are. There are a lot of molds out there with cross venting from cavity to cavity. So that could be what you're looking at. Try it.

[captaint]

pcarpenter - If it were me, I would heat up the pot and see what happends. Might throw some great boolits. Just my take. Mike

[brotherdarrell]

I got one of the new 6-cav. molds a couple of weeks ago, the 452-200-rnfp. It is an absolute dream to cast with, no fins and the boolits drop out just fine after I de-burred the mold. Definitely a thumbs up.

brotherdarrell

[Bardo]

Just got one from Midway today and its the same way. It is also marked what mold it is on the top. I sold all my Lee's but really liked this boolit so decided to get it. I hope it cast nice.

Bardo

59944

[pcarpenter]

I had a small amount of time to try out the mold last night. The good news is that I got no feathers or fins so clearly that amount of gap is adequate for venting and not a problem from a leakage standpoint. I found my older 358-158 RNFP mold and it does not have this method of venting. As you point out (Bardo), they have started marking the top of the molds with the bullet size, too, so maybe there have been several changes in recent times. They do look very well machined for something you can buy for under $40.

The bad news is that I could not get the dimensions, that I wanted--at least not on my first try last night. I may not have been running the mold hot enough. Most of the aluminum molds I have used sink away a lot of heat. I pre-heated it to about 400 and had my lead first at 750 and then 775 trying to get good fill out. I can't remember where (thermometer) my other Lee 6 cavity runs best. This is also complicated by the fact that I first used my newly-constructed temp controller last night. When you get all that feedback (big glowing numbers staring you in the face), it's hard to make yourself run the heat up to some seemingly crazy temp well above the melt point, in order to get the job done.

I think having a big glowing 800* number up there would seem just wrong. On the other hand, the bullets were out of round and about .356 one direction and .357something the other way. I'm willing to size them to make them round but really wanted to get *at least* .357 out of them. I have several different guns in which I want to use them and I need to do some chamber/throat casting to see what I need size wise to fill the throat and also how much latitude I have in the chamber for a loaded round with a fat bullet. Seems that way too many guns are built nowdays without cast bullets in mind.

[Bardo]

I cleaned mine and drilled and tapped 2 set screws to hold the bolts in place. I had no fins and it didnt seem to get lead on the face. Mine all dropped around .360. I have never had a problem with Lees casting to small. I cast usually between 625-675 with 2/3 WW 1/3 pure and 1% tin. My problem is they always seem to get a little fin on the base like the sprue plate wasnt on tight. There is no lead on the top of the mold or sprue plate. I do use bull plate and have messed around with how tight the sprue plate is and the flow rate of the lead. Anyone else have this problem. I like to size nose first with a star sizer so its a bigger problem. But sometimes I size base first and that helps. Also I dont get this with other molds.

Here is a picture of a few boolits. Maybe 1 in 10 is like this.

59964

Bardo

[pcarpenter]

I cleaned mine and drilled and tapped 2 set screws to hold the bolts in place. I had no fins and it didnt seem to get lead on the face. Mine all dropped around .360. I have never had a problem with Lees casting to small. I cast usually between 625-675 with 2/3 WW 1/3 pure and 1% tin. My problem is they always seem to get a little fin on the base like the sprue plate wasnt on tight. There is no lead on the top of the mold or sprue plate. I do use bull plate and have messed around with how tight the sprue plate is and the flow rate of the lead. Anyone else have this problem. I like to size nose first with a star sizer so its a bigger problem. But sometimes I size base first and that helps. Also I dont get this with other molds.

Here is a picture of a few boolits. Maybe 1 in 10 is like this.

Bardo

I have had that a few times after a mold has gotten too hot...in effect it's warpage. It's probably more apt to happen with a nice long sprue plate...and probably moreso with the aluminum sprue plate that Lee uses on the 6c molds since aluminum has a much higher coefficient of expansion than steel (or brass). We all talk about how aluminum molds need to be warmer since they conduct heat away so well, but in my experience they also suffer from the opposite problem since they get heated up pretty quickly when we maintain the sort of pace that's needed to keep them in the right range. I also have observed another problem....likely related.....one side (I think the side closest to the adjacent bullet cavity) of each bullet will often be hotter and start frosting sooner than say the outside edge of the same cavity.

Don't get me wrong, I think aluminum works adequately well for bullet molds, and it machines nicely, but it may not be the ideal material for the job. I do think that a steel sprue plate would improve this sort of issue with these molds. I know someone was making them for a while. It's hard to think about spending too much on a replacement sprue plate for a mold that cost me $35 or so. In your case, using a Star sizer, though, it may make more sense.

Edit-- by the way, my mold is casting to at least it's nominal size. The trouble stems from the fact that the perceived "standard" for 9mm barrels (.355 groove diameter) isn't always correct so folks here have had better luck if they can cast/size to .357 or even .358. I may have to give up and buy maybe one of the 357-125 RF molds instead. I read a lot here and some have had good luck with that in their 9's.
Paul

[MT Chambers]

I wouldn't be satisfied with any of that flashing on my bullets, I'd fix it, one way or another.

[Bardo]

Thats right yours was a 9mm boolit so it isnt casting undersized. As for the base of my boolit having "flashing" I can only figure it must be me and how im doing things. The 6 cavities are the longest molds I have, and all my other molds have steel sprue plates. But most my other molds are 4 cavities and Iron, Aluminum or Brass. I dont think I'm getting the mold to hot because my boolits arent frosted. I sure wish I could figure it out because I like several Lee boolits and there 6 cavities are priced right.

Bardo

[pcarpenter]

You mentioned messing around with how tight the sprue plate is-- since there's no lock screw, the bolt/thimble/spring assembly should be tightened all the way down. If you removed the assembly, then the right assembly order is bolt, spring washer, thimble such that the spring washer always applies some downward force on that thimble. The thimble in turn pushes down on the latching notch in the sprue plate. I chucked my thimbles up on an arbor in the lathe and polished them so that the sprue plate slides under with ease. It's an alumnium sprue plate after all and the thimble came with a moderately rough finish which will eventually chew on the sprue plate.

What I was trying to describe before is something I noticed with longer molds I have even from NOE-- as they warm up, the sprue plate becomes "looser" and no longer fits as tight to the top of the mold as it did when the mold was cold. I had one of my NOE molds (a 5 cavity 316299) get too warm and started getting the fins on the tail of the bullet. I think I was also opening the sprue a bit prematurely which could be an issue for you too? It would be worth looking at the fins to see if there are "wipe marks" in the lead. With the multi-cavity molds, obviously waiting too long after the sprue flashes off is a bad thing.....it makes it very hard to cut say 5-6 sprues simultaneously. But, it's easy to be a bit over-zealous and open it a bit too soon and get a "wiping" effect on the base of the bullet I suppose.

[jabilli]

I'm sure you've already tried but I'll ask anyhow- Have ya tried giving the bolt a tightening after the mold is heated up?

Something I find that makes my using the 6 cavity a bit easier: I Alternate the order in which I fill- Far end toward me, my end out, far end toward me, my end out... This seems to help keep the ends of the mold closer in temp.

One thing about the mold that I don't like quite so much- The fact the sprue-handle isn't solid- It rocks on a pivot, I see it's function and actually makes life easier, it's just, the fact it wiggles around tends me make me think I'm going to break it. :-p