Help! 5 cav aluminum mold and cratered bases
- Thread starter Dimner
- Start date
Ian
Notorious member
I mean looking at the inside face of the mould, bullet base up. Go over it with at least 10x magnification, you'll see it. It's an artifact of the tool which bored the cavity in the blocks. One reason people like iron moulds so much (even though many do not realize why) is that iron powders when it's machined and doesn't pack flashing into the vent lines. Aluminum and brass both get clogged up. With deep lube groove designs, venting in the driving band area is especially important.
I use a carbide-tipped scribe but even a utility knife blade will do to plow out the flashing.
I use a carbide-tipped scribe but even a utility knife blade will do to plow out the flashing.
fiver
Well-Known Member
pour every third pour from back to front, instead of from front to back.
take the mold out from under the heat so you don't get it too hot in the front and too cold in the back.
all your doing is getting the entire mold to the same temp.
once you have that then you can adjust the sprue plate temp to get the cuts you like.
think about the mold as a heat sink as the hotter sections cool down faster [relatively] they are pulling the heat from the colder sections.[IE the area that last got the heat]
take the mold out from under the heat so you don't get it too hot in the front and too cold in the back.
all your doing is getting the entire mold to the same temp.
once you have that then you can adjust the sprue plate temp to get the cuts you like.
think about the mold as a heat sink as the hotter sections cool down faster [relatively] they are pulling the heat from the colder sections.[IE the area that last got the heat]
RBHarter
West Central AR
I have a couple of moulds like that .
This applies to a dozen 4&5 c NOE aluminum moulds .
When I start chasing mould temp that way , I only ladle pour , I just rest the mould on top of the pot , usually about the 2nd cav from the hinge . I hinge on the handle end 25,26,27 cal , once pace is set , are about 3 on 2 off , the 35s at 125+ generally don't need it maybe 2 of 6-8 pours .
The 62 gr 22 goes back on the pot every pour and gets the whole 2000 gr poured over it .
That itty bitty 225-37 5c would make maybe 10 pours and have to go back on the hot plate .
The 312-230 5c also went on the pot full span rest like 4/5 pours as it would get the drip wrinkle in the bands .
I could pour the 5c 454424 copy all day as long as the pot could keep up with me .
I guess you should think of it as pouring and balancing heat .......
This applies to a dozen 4&5 c NOE aluminum moulds .
When I start chasing mould temp that way , I only ladle pour , I just rest the mould on top of the pot , usually about the 2nd cav from the hinge . I hinge on the handle end 25,26,27 cal , once pace is set , are about 3 on 2 off , the 35s at 125+ generally don't need it maybe 2 of 6-8 pours .
The 62 gr 22 goes back on the pot every pour and gets the whole 2000 gr poured over it .
That itty bitty 225-37 5c would make maybe 10 pours and have to go back on the hot plate .
The 312-230 5c also went on the pot full span rest like 4/5 pours as it would get the drip wrinkle in the bands .
I could pour the 5c 454424 copy all day as long as the pot could keep up with me .
I guess you should think of it as pouring and balancing heat .......
RBHarter
West Central AR
I will say that the very first NOE I bought fought me to a finish , seriously , fits and kittens .
The second one I actually read the start up cues ..........wash with HOT water , Blue Dawn , and a soft toothbrush . I put a couple of drops on a wet brush and make 5-6 passes in each cavity. Then heat to casting temperature and let cool to room temperature 3 times . The 2nd time I lube the sprue hinge with the wonder lube (synthetic 2 stroke oil) and with just enough to change the color of the face before I do the 3rd heat cycle with the sprue plate down . It makes a huge difference.
Wanna talk about a great mould much bragged about as a divine gift that is was about 10 seconds from chucking off a cliff or dumping in someone else's lap . If you live in a dry environment where rust isn't a thing , do not buy a new brass mould and expect it to work in less than about 10-12 casting sessions and at least that many additional heat cycles over 2+ months . Yeah MP HB/PB brass .......... Talk about a fight . Oh sure , it's a dream now but the patina has really come on in the rust belt .
The second one I actually read the start up cues ..........wash with HOT water , Blue Dawn , and a soft toothbrush . I put a couple of drops on a wet brush and make 5-6 passes in each cavity. Then heat to casting temperature and let cool to room temperature 3 times . The 2nd time I lube the sprue hinge with the wonder lube (synthetic 2 stroke oil) and with just enough to change the color of the face before I do the 3rd heat cycle with the sprue plate down . It makes a huge difference.
Wanna talk about a great mould much bragged about as a divine gift that is was about 10 seconds from chucking off a cliff or dumping in someone else's lap . If you live in a dry environment where rust isn't a thing , do not buy a new brass mould and expect it to work in less than about 10-12 casting sessions and at least that many additional heat cycles over 2+ months . Yeah MP HB/PB brass .......... Talk about a fight . Oh sure , it's a dream now but the patina has really come on in the rust belt .
L Ross
Well-Known Member
I remember sniveling about this mould after I tried to use it, and am recalling now that I followed Ian's advice about the venting. Also, part of the problem was it also clung to a couple of bullets so tenaciously that by the time I tap tap tap tap tapped to get hem to drop the mould was cooling excessively. Using magnification to look for tiny burrs and removing them with care and a dental pick helped. As did several casting cycles.
I have not cast with it in at least two years because I had tubs of 312-155-2R and the XCB's cast up. Then Covid hit and one shoot had poor attendance. Then last June Sue and I got sick right before the shoot and we had to cancel it. Thus the supply of bullets cast ahead has allowed those moulds to sit idle.
Since deburring, vent clearing, and I swear a certain level of seasoning takes place from casting cycles, the mould was better and I found other things to swear at and about.
I have not cast with it in at least two years because I had tubs of 312-155-2R and the XCB's cast up. Then Covid hit and one shoot had poor attendance. Then last June Sue and I got sick right before the shoot and we had to cancel it. Thus the supply of bullets cast ahead has allowed those moulds to sit idle.
Since deburring, vent clearing, and I swear a certain level of seasoning takes place from casting cycles, the mould was better and I found other things to swear at and about.
Bret4207
At the casting bench in the sky. RIP Bret.
Works that way with most aluminum moulds for me.
Bret4207
At the casting bench in the sky. RIP Bret.
It's not something you do, it's something that happens and corrects itself through repeated heating and cooling cycles. Maybe 2-3 sessions, maybe 7 or 8! Sometimes it even takes lapping/polishing to get whatever is in the cavities out, not often for me at least, but a couple times. And more with Lees than any other brand I've ever used.
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Bret4207
At the casting bench in the sky. RIP Bret.
Well the first question is- Is it cratering (alloy not fully filling the cavity) or is it ripping some material out as you open the sprue plate? Cratering at the mould/sprue plate interface is one thing. Ripping mechanically is another. Cratering would be a venting/heat issue most likely. Ripping is going to likely be the result of a sprue plate that's not as sharp as it could be, IMO at least. I'd look at both my bullet bases and the cut off sprues, especially the sprues now that I think on it. That should tell you more than the bullet base. I've cleaned up and "sharpened" a lot of sprue plates, 'specially on Lees. Beyond that and into "whats acceptable?", if it is cratering, then how do you know you don't have similar inclusions/cratering in the bullet body that are hidden by the surrounding metal? You don't. You could weigh bullets after visual culling. For me, since I'm not Joe Benchrest, I visually cull, prefer nice smooth bases and will toss the ones that are ugly enough. What makes one base "too ugly"? Heck! I dunno, the ones that look a lot worse than the majority. A more or less centered crater of average for the session size that amounts to a few tenths of a grain, or less!, with or without a GC over it...how good is my gun shooting with me behind the trigger in the first place? We all want perfection, but none of us get it. Pope and those boys used to use pound swages on castings because of the idea of interior cavities throwing a bullet out. How far do you want to go? I'm a whole lot more concerned with a near perfect outside of the base fill out than I am with a dinky divot in the center of the base. Let the bullet get cockeyed in the neck by a couple thou and I bet you see more variation on the target than from a pretty centered divot in the base.
You're going to have to look, think, research and try some different ideas to get to a point that's acceptable to you. What I or anyone else thinks doesn't mean squat. You decide where you want to go and how far you're willing to pursue your idea of "good enough vs perfection".
Dimner
Named Man
Well, last night I went back to the bottom pour pot. For the single reason that I can sit while casting using a bottom pour.
My dog booby trapped me last night. She loves her antlers for chewing. Like a dummy I walked in-between the couch and the coffee table in a dark room. Took a direct stab from an expertly gnawed and sharpened antler tine. Right at the base of the big toe pad. At least a quarter inch deep. So I'm going to have to be casting while sitting down for a few days. She's a lovely pup. Very concerned at what all the yelling and cussing was about when it happened.
Anyway, the venting mods did help run cooler without band defects. Unfortunately it brought back an issue that I thought I had gotten through a few castings ago. I guess the burr is now on the cavity side and the bullets take a fair bit of persuasion to drop from the mold. This leaves some markings on the driving bands. Not a huge deal, I just need to work that burr free rather than have it in the cavity or in the vent line.
I don't have my cadence down 100% yet, but I found the best success with going back to the method of setting the sprue on a damp cloth... aka a version of BruceB's speed casting method. Found some success in a sequence of 1st pour damp cloth sprue quench, 2nd pour damp cloth sprue quench, 3rd pour wait 3 seconds after sprue color change & open... then repeat sequence. Just need to work on the timing. I can tell when everything is getting too cold based on how hard it is for me to open the sprue plate. I always do this by hand, so I can get a feel for the mold temp.
As for the base defects, these are craters caused by the sprue ripping the lead out, so yes, sprue ripping is a much better term. I was hoping someone had the experience with this kind of defect to take a look at the pic and let me know which to avoid. I can always do a test to see which defects matter, but you know... it's all about saving as many primers as possible. Also, since I do not have a quality load yet, I have to find that first with good bases before I can see what defects impact accuracy. (it annoys me we, as a community, don't use the word precision)
Anyway, the bottom line is, Thank you everyone for your help. I'm not there yet, but there is hope now that I will find the sweet spot and be able to get 100% of the body defect issues sorted out and base reject rate down to about 15-20%. With a 5 cavity mold, I'm more than okay with those results. In all honesty, it takes like 45 minutes to fill an entire quart yogurt container up with these bullets. So with just a few sessions, when everything is firing on all cylinders, I'll have more bullets than I want to use my primer supply on.
Lessons learned: Stick with 2 cav, 3 cav, or steel molds. Those are idiot proof. 4 cavs get tricky, but the sweet spot is found pretty easy. 5 cav molds, the sweet spot is smaller than I care to ever deal with again.
My dog booby trapped me last night. She loves her antlers for chewing. Like a dummy I walked in-between the couch and the coffee table in a dark room. Took a direct stab from an expertly gnawed and sharpened antler tine. Right at the base of the big toe pad. At least a quarter inch deep. So I'm going to have to be casting while sitting down for a few days. She's a lovely pup. Very concerned at what all the yelling and cussing was about when it happened.
Anyway, the venting mods did help run cooler without band defects. Unfortunately it brought back an issue that I thought I had gotten through a few castings ago. I guess the burr is now on the cavity side and the bullets take a fair bit of persuasion to drop from the mold. This leaves some markings on the driving bands. Not a huge deal, I just need to work that burr free rather than have it in the cavity or in the vent line.
I don't have my cadence down 100% yet, but I found the best success with going back to the method of setting the sprue on a damp cloth... aka a version of BruceB's speed casting method. Found some success in a sequence of 1st pour damp cloth sprue quench, 2nd pour damp cloth sprue quench, 3rd pour wait 3 seconds after sprue color change & open... then repeat sequence. Just need to work on the timing. I can tell when everything is getting too cold based on how hard it is for me to open the sprue plate. I always do this by hand, so I can get a feel for the mold temp.
As for the base defects, these are craters caused by the sprue ripping the lead out, so yes, sprue ripping is a much better term. I was hoping someone had the experience with this kind of defect to take a look at the pic and let me know which to avoid. I can always do a test to see which defects matter, but you know... it's all about saving as many primers as possible. Also, since I do not have a quality load yet, I have to find that first with good bases before I can see what defects impact accuracy. (it annoys me we, as a community, don't use the word precision)
Anyway, the bottom line is, Thank you everyone for your help. I'm not there yet, but there is hope now that I will find the sweet spot and be able to get 100% of the body defect issues sorted out and base reject rate down to about 15-20%. With a 5 cavity mold, I'm more than okay with those results. In all honesty, it takes like 45 minutes to fill an entire quart yogurt container up with these bullets. So with just a few sessions, when everything is firing on all cylinders, I'll have more bullets than I want to use my primer supply on.
Lessons learned: Stick with 2 cav, 3 cav, or steel molds. Those are idiot proof. 4 cavs get tricky, but the sweet spot is found pretty easy. 5 cav molds, the sweet spot is smaller than I care to ever deal with again.
Even with 4 x pistol moulds I pour from one end for awhile, then switch ends. I also drop the mould on a hard surface after the pour to force alloy into the sprue hole while liquid. Don't bang it, just so it gets a good thump. On the 6x I cast starting from the end where the sprue pivot is, as that end gets cold faster and harder to cut sprue - that was a Lee mould and the cutting handle could break - cheap pot metal.
Dimner
Named Man
Winner!
Last night I had tried this without any luck. I was using the face of my rawhide mallet to tap, about 1 1/2" diameter. Well this morning I tried using the handle of my mallet right before the head, so basically a 5/8" ish dowel. Tapping the 3rd and 4th cavities works wonders! I don't get what black magic it does, but it means I either get all good sprue cuts, or just 1 or two with very acceptable minor cratering. Now I can keep my tempo consistent and not do any fan or damp cloth trickery that affects the mold temp. Thank you Jim!
And Popper, this process sounds very similar to what you are talking about with thumping the base of the mold on the bench.
Bret4207
At the casting bench in the sky. RIP Bret.
It's not the number of cavities, it's the mould. I have a 10 cav H+G that is hands down about the easiest mould I own to cast with.
Winelover
North Central Arkansas
I don't heat cycle any new moulds. I've always only used brake cleaner to clean new moulds. Only time I use a rawhide mallet to open a mold is for the first couple of pours. If I can't open any multi cavity mold, with a glove hand, its not at the right temp. I don't even look at the castings till then. The #2 Rowell is your friend for multi cavity moulds. For small calibers, you may get away with a #1 Rowell.
Ian
Notorious member
If H&G had used aluminum it WOULD have been a problem.
Heat cycling was a process invented by a certain mould manufacturer who was having chronic problems with alignment pins getting loose and falling out on the first heat. After several heats without casting, the pins oxidize and sort of "oxide jack" themselves permanently in place. Heat cycling may or may not build a helpful oxide layer on the surface of the cavities. If you want that non-stick aluminum coating, boil in Dawn and distilled water for five minutes....the blocks will look terrible but will be much less apt to collect little bits of flashing.
Heat cycling was a process invented by a certain mould manufacturer who was having chronic problems with alignment pins getting loose and falling out on the first heat. After several heats without casting, the pins oxidize and sort of "oxide jack" themselves permanently in place. Heat cycling may or may not build a helpful oxide layer on the surface of the cavities. If you want that non-stick aluminum coating, boil in Dawn and distilled water for five minutes....the blocks will look terrible but will be much less apt to collect little bits of flashing.