Brass Mold Troubles

[Master_Mechanic]

Good morning everyone,
I have been casting for about 3 years now, most of my casting has been done with iron molds. Recently I ventured into the custom brass hp world and have picked up several mp molds. I took the advice in the stickies and cleaned, heat-cycled and lubed the molds. I preheat the molds on a hotplate, but i have trouble with proper fillout. If the mold is too cold the wrinkle or if there too hot the bases smear regardless of how long i wait to cut the sprue. Ive tried different temps from 650 to 700. I'm ladle casting with the lyman ladle. Any thoughts on what I should do?

[44man]

I had the same problem with a huge brass mold I borrowed. They are hard to keep at the right heat. It took me a while to get the hang of.

[dragon813gt]

Those lead temps have been to low for me to get everything to work right. I usually run it at 735. This allows for the mold and pins to stay hot and the sprue to harden in 5-8 seconds.

[Master_Mechanic]

if i run the lead and mold hotter it seems like i smear the base when the sprue cools.

[Jailer]

if i run the lead and mold hotter it seems like i smear the base when the sprue cools.

Pour a smaller sprue puddle.

[trixter]

With mine in 45 cal, I run the lead between 725º and 750º, and cast just as fast as the mold will let me; my cadence is about a 1001 - 1007 for the sprue, then another 1001-1010 to open and it works very well, just a light tap on the pins and they all fall out. I heat the mold on a hot plate while the lead is melting, and checked it with my thermometer one day, it was about 550º off the hot plate. I get perfect boolits from the first cast. My other MP mold in 45 SWC, a H&G 68 clone is another story and works very differently. {another story for another time}

[Master_Mechanic]

With mine in 45 cal, I run the lead between 725º and 750º, and cast just as fast as the mold will let me; my cadence is about a 1001 - 1007 for the sprue, then another 1001-1010 to open and it works very well, just a light tap on the pins and they all fall out. I heat the mold on a hot plate while the lead is melting, and checked it with my thermometer one day, it was about 550º off the hot plate. I get perfect boolits from the first cast. My other MP mold in 45 SWC, a H&G 68 clone is another story and works very differently. {another story for another time}

the 1001-1007 count, is that from pour or from puddle hardening?

[dragon813gt]

the 1001-1007 count, is that from pour or from puddle hardening?

Judging by what he wrote, yes. 7 seconds for sprue to harden, open plate, a 10 count, then open the blocks. If your sprue isn't hardening then you need to cool the sprue plate off. This is easily done by leaving it swung open for a bit or a moist towel. You can regulate the sprue plate temp by pouring a smaller or larger puddle.

[Master_Mechanic]

That might just be my issue, too cold and not waiting long enough after hardening to cut then not waiting that extra time before opening the mold. i have an aluminum noe mold that works very well, but it takes longer to cut the sprue being a 5 cavity. Thanks guys, i will keep trying.

[44man]

Like turning cold rolled into tool steel, maybe some metals are not good for molds. The huge mass of brass molds might not be the right way to go.

[dragon813gt]

Like turning cold rolled into tool steel, maybe some metals are not good for molds. The huge mass of brass molds might not be the right way to go.

Brass is perfectly acceptable it just requires a different technique. I prefer it because it holds heat and I can cast at a relaxed pace. Once they're up to temp they stay there easily. But I've found them to have a narrow operating band. I swore off aluminium because of Lee molds. I now have two aluminium NOE molds, two more on the way, that have restored my faith in that metal. Also have one from Accurate that's a joy to use as well.

[Love Life]

Cast hot and let the sprue harden up. My brass moulds make very nice boolits, but I much prefer iron moulds.

[paul h]

I find brass to me the most sensitive mold material for temperatures, kinda like Goldi Locks who doesn't like her porridge too hot or too cold, brass needs to be at just the right temp to make good boolits.

[Springfield]

Bulplate Sprue Lube will help with the smearing, and may eliminate all your problems. I can send you a small sample bottle if you like, I have a few from molds I have bought. Works wonders, it really does.

[Master_Mechanic]

Bulplate Sprue Lube will help with the smearing, and may eliminate all your problems. I can send you a small sample bottle if you like, I have a few from molds I have bought. Works wonders, it really does.
I have several bottles of the lube, i never had luck using it on the top of the molds/bottom of the plate without contaminateing the cavities.

[dragon813gt]

I have several bottles of the lube, i never had luck using it on the top of the molds/bottom of the plate without contaminateing the cavities.

You used to much if it got into the cavities. The lube that came w/ the mold works just fine. It's best to apply it when the plate is hot. A little bit goes a long way.

[Master_Mechanic]

fill the cavities with lead, put a dab of lube on a qtip and apply to the mold? seems to allways effect my boolits. i will try agian.

[44man]

Brass does have a narrow band, seems to give up heat fast or retain it. Just takes practice.
I hate lee aluminum but have no trouble casting. I made my molds from aircraft aluminum and it is as tough as iron molds. I find no difference at all.
Brass makes a mold like a jewel but the setting can lose the diamond.

[Smoke4320]

Like others have said Brass (for me ) seems to like higher than 725 degrees.. For mine its 735 as the sweet spot ..
for the mold lubing I just put some on a q-tip and make one swipe around the Sprew plate and a very quick light wipe between the holes. a little on the pivot pins and go about every 150-200 bullets I do it again

[quasi]

Brass does have a narrow band, seems to give up heat fast or retain it. Just takes practice.
I hate lee aluminum but have no trouble casting. I made my molds from aircraft aluminum and it is as tough as iron molds. I find no difference at all.
Brass makes a mold like a jewel but the setting can lose the diamond.

Aircraft Aluminum? What is that? Tough as Iron moulds? I think you are shoveling with both hands.

[gwpercle]

Hold the mould in front of a small fan to speed the sprue hardening. Another trick is cast with two moulds, fill one, set down to cool while filling the second, set second one down and open the first, it will have cooled by then. Good excuse to buy two moulds....right!
Gary

[Smoke4320]

2024-T4 & 6061-T6 are Aircraft aluminum grade and there are several others

[44man]

Aircraft Aluminum? What is that? Tough as Iron moulds? I think you are shoveling with both hands.
Good stuff, very hard and tough. I worked for an airline and got a huge chunk. Even the sprue plate does not mark it. I believe I have the 7000 series metal. It seems harder then 6061 but might be the higher 6000 series. 7068 aluminium alloy is the strongest commercially available aluminium alloy (http://en.wikipedia.org/wiki/Aluminium_alloy), and comparable to that of some steels (http://en.wikipedia.org/wiki/Steel).[1] (http://en.wikipedia.org/wiki/7068_aluminium_alloy#cite_note-1) 7068-T6511 has typical ultimate tensile strength of 103 ksi (710 MPa) versus a similar product produced from 7075-T6511 that would have a typical ultimate tensile strength of 93 ksi (640 MPa). Typical yield strength for alloy 7068-T6511 is 99 ksi (680 MPa) versus 86 ksi (590 MPa) for a similar product produced from 7075-T6511.[citation needed (http://en.wikipedia.org/wiki/Wikipedia:Citation_needed)] Strength allowables for this alloy are provided in Metallic Materials Properties Development.
Sure different then the soft junk lee uses.

[44man]

6061 would make a great mold. The custom mold makers use a good grade of aluminum.

[quasi]

I was not aware 7000 series Aluminum was used in Aircraft. As far as casting with brass moulds or other metals, I find the Bruce B. speed casting method works well. Using a wet cloth or sponge to cool the sprue and or the bottom of the mould works well for me.

[Doc Highwall]

Where I worked in the aircraft we used a lot of 6061-T6 and we also used 7075 along with a lot of other metals.

After I fill the mould cavities I look at the sprue puddle and watch for it to change color showing that it just froze, I then give it a three to four second count before I cut the sprue and squeeze down in the sprue plate while cutting.

[ofreen]

Hold the mould in front of a small fan to speed the sprue hardening. Another trick is cast with two moulds, fill one, set down to cool while filling the second, set second one down and open the first, it will have cooled by then. Good excuse to buy two moulds....right!
Gary

This is an answer. I rarely cast with only one mold. You can move right along without as much problem with overheating.

[GabbyM]

Having machined 7000 series aluminum. I can tell you it is tough to cut to put it mildly.

I like the few brass molds I own. Do end up with frosted bullets some times but so what? I have a fantastic MiHec 30-180-SP-HP.
Pointy bullet hollow points aren't easy to cast. This mold does great. Once the pins get hot enough to allow lead to flow and form up nice. Only takes a couple cast after pre heating on top of my pot.

You do have to be careful with brass a you can get things to hot and solder them together.

A two cavity brass mold is all the weight I care for in a hand cast mold. 4 and 6 cavities I like aluminum to save my wrist.
I use a fan for cooling. Two molds at a time is to much like work.

[Forgetful]

Buy yourself a digital mold thermometer and a pot thermometer and get rid of all the guesswork. I've been having issues with the last aluminum mold I bought, it was dropping fine for the first two sessions. Started up a third session and can't get good fillout with the same alloy and what I thought was the same temperature. Cleaned, re-lubed, tried again, no go. NOE's thermometers are in the mail. Tired of guessing. I haven't had a problem in the past, because I was happy with 90% or 95% efficiency when things are working right.

[Dale53]

I have been casting bullets since 1950. I've even done commercial casting. However, an old dog CAN learn new tricks. Just a few years ago, I read an article by Mike Venturino where he mentioned using a manicurists fan to cool his sprues. I found one at Target (not in the ladies cosmetics but in the fan department) for about $7.00. I later saw one in Walmart. These may be in stores on a seasonal basis but can be had online. Here is one similar to what I have:

http://www.walmart.com/ip/QV-Tools-Table-Fan/39889207?action=product_interest&action_type=image&placement_id=irs_top&strategy=PWVUB&visitor_id=68741663276&category=0%3A1072864%3A133032%3A133118&client_guid=359e4778-b325-457d-8734-e231bee16622&config_id=2&parent_item_id=25209563&guid=fe918414-56a0-4e3b-91ee-0f719bde9d9f&bucket_id=irsbucketdefault&findingMethod=p13n

At any rate, I mounted it about 18" above my casting table. When I pull the mould (bottom cast with an RCBS Promelt) from the furnace the fan blows on the top of the mould. In two to three seconds, the sprue is set - YMMV. I got it to speed up casting. Normally, when the mould is hot enough to properly cast it takes too long for the sprue to set. This allows the best of both worlds. An additional benefit that I discovered is, after you establish a cadence, it maintains proper mould temperature. No overheating, etc.

I have NO problems casting with brass (I have several Mihec brass moulds and LOVE them), aluminum (Mihec and NOE as well as Lee and NEI), or iron (H&G, Lyman, RCBS, and Saeco).

I pre-heat ALL moulds on a hotplate (I bring my moulds up to a predetermined temperature just under casting level - then one or two casts and I am ready to go). My suggestion will keep you from overheating and warping a mould.

The few dollars you spend on a "personal fan" will go a long way to solving time for sprue to set and overheating of moulds from a good casting cadence.

Here's a picture of my set up:

http://i269.photobucket.com/albums/jj80/Dale53/Castingfan-3723.jpg (http://s269.photobucket.com/user/Dale53/media/Castingfan-3723.jpg.html)

Just a thought or two...

Dale53