We have been having a little Feb. thaw..temp in low 50's, so I decided to try out a couple of new to me .38 wadcutter moulds. First up was a like new Lyman 358081BV. Using a ww/50-50 solder alloy, bullets dropped perfectly filled out as soon as mould was up to temp. This alloy is probably tin rich as every toolmark in cavity showed up on bullets. Next I tried an old early Ideal non-vented dbl. cav. 358245 112gr. wadcutter. Bullets from r.h. cavity (looking at mould from top in normal casting position) came out perfectly filled out...However, those from l.h. cavity failed to completely fill out the two tiny middle drive bands on one side of bullet. I have had this problem happen before on account of first cavity blocking air release..but even when filling this cavity first..still failed to fillout. Tried upping & lowering temp to no effect. The closest I came to success was by letting alloy fall considerable distance into mould ( I dipper cast) and then bringing 1/2 full dipper into firm contact with sprue hole and letting sit for few seconds before letting contents spill over sprue plate...messy, but bands still were rounded on top & bottom edges. Miking cooled castings revealed bands were .3585" so will probly be OK. The bands on perfect front cavity miked .359 to .3585. Mould was carefully washed in hot water with Dawn before using. Any ideas? Thanks.
Rounded driving bands?
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Ian
Notorious member
Temp of WHAT????
If it wouldn't pressure fill or drizzle fill you are dealing with a mould contamination problem or a mould block temperature problem, not a venting problem.
Will the sprue plate swing freely with a bump of your little finger, or is it tighter than that ?
I'd clean the mould again. I'd sit the mould on the edge of the pot for 15 minutes, let the blocks get HOT, cast at a rapid pace and get the mould blocks hot to the point that the sprue isn't hardening well and the bullets are on the edge of frosting.
Now cool the sprue plate with a damp sponge or wet cloth and start casting at a good pace, hopefully things will improve.
As you can see I'm suspicious of a mold block temp problem. ( Blocks not hot enough )
Not all casters will agree with what I'm about to say, but get a butane cigarette lighter and put a thin film of soot in the mold cavities and then cast with the mould. If it doesn't help, it can be cleaned out with no harm to your mould.
Ben
I'd clean the mould again. I'd sit the mould on the edge of the pot for 15 minutes, let the blocks get HOT, cast at a rapid pace and get the mould blocks hot to the point that the sprue isn't hardening well and the bullets are on the edge of frosting.
Now cool the sprue plate with a damp sponge or wet cloth and start casting at a good pace, hopefully things will improve.
As you can see I'm suspicious of a mold block temp problem. ( Blocks not hot enough )
Not all casters will agree with what I'm about to say, but get a butane cigarette lighter and put a thin film of soot in the mold cavities and then cast with the mould. If it doesn't help, it can be cleaned out with no harm to your mould.
Ben
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fiver
Well-Known Member
since it's just one cavity I would look at the sprue plate tension.
if the plate is too tight it will open up the air flow on the cavity away from the bolt.
if it's too loose it can let the plate tip the other way.
I have also seen the plate tension change on a hot to cold mold.
since this is a non-vented mold the air only has the sprue plate area to escape.
you might also look at cutting the edge of the blocks with a super fine file or a whet stone on the cavity that isn't venting well.
one other thing to look at is the drive bands themselves.
are they a grey mottled color when the rest of the boolit is silver or are they semi-whitish when the rest of the boolit is grey.
if so I think your getting a hot spot from the alloy hitting right there every time causing frosting.
if the plate is too tight it will open up the air flow on the cavity away from the bolt.
if it's too loose it can let the plate tip the other way.
I have also seen the plate tension change on a hot to cold mold.
since this is a non-vented mold the air only has the sprue plate area to escape.
you might also look at cutting the edge of the blocks with a super fine file or a whet stone on the cavity that isn't venting well.
one other thing to look at is the drive bands themselves.
are they a grey mottled color when the rest of the boolit is silver or are they semi-whitish when the rest of the boolit is grey.
if so I think your getting a hot spot from the alloy hitting right there every time causing frosting.
Ian
Notorious member
I'm still unclear if it's the left side block half making the bands of the bullet(s) not sharp on just that one side of if it's the rear cavity not making sharp edges all the way around the bullet.
Sometimes I get one side of one cavity of a multi-cavity mould that starts rounding the bands a little, usually it's a cold spot around a handle pin or near the end, or it's related to one or more bullets sticking consistently in one side of the blocks and requiring a whack to shuck out, thus making uneven heat between one side and the other of one cavity. If you're running the ragged edge of fillout temp to try and make the bullets cast a certain size, it doesn't take a lot to upset the temp around one cavity in one block half or the other to the point that defects occur.
A little smoke like Ben said is good for diagnostics...if it fixes the problem the cavity was contaminated somehow. If the bands don't fill but the base is sharp, it's likely not venting, but if bands and base are rounded I suspect cold mould first and sprue venting second, a file or loosen the sprue plate a titch may also be in order as was mentioned.
Sometimes I get one side of one cavity of a multi-cavity mould that starts rounding the bands a little, usually it's a cold spot around a handle pin or near the end, or it's related to one or more bullets sticking consistently in one side of the blocks and requiring a whack to shuck out, thus making uneven heat between one side and the other of one cavity. If you're running the ragged edge of fillout temp to try and make the bullets cast a certain size, it doesn't take a lot to upset the temp around one cavity in one block half or the other to the point that defects occur.
A little smoke like Ben said is good for diagnostics...if it fixes the problem the cavity was contaminated somehow. If the bands don't fill but the base is sharp, it's likely not venting, but if bands and base are rounded I suspect cold mould first and sprue venting second, a file or loosen the sprue plate a titch may also be in order as was mentioned.
fiver
Well-Known Member
this reminds me of my 375449 mold.
it's a normal sized 2 cavity lyman mold but with what seems like huge cavity's in it.
I have to run that thing like it's an rcbs 2 cavity 22 cal mold.
if I make about 5 pours a minute and keep it that speed the boolits come out shiny and soft but the drive bands are sharp and well filled out.
I think that one side of the small lyman mold might be cooling off like Ian is talking about [handles act like a heat sink]
I know the 435gr 2 cavity aluminum LEE 45-70 mold I have needs that speed because it does cool off quickly.
the one benefit is that they both produce a huge pile of boolits quickly.
it's a normal sized 2 cavity lyman mold but with what seems like huge cavity's in it.
I have to run that thing like it's an rcbs 2 cavity 22 cal mold.
if I make about 5 pours a minute and keep it that speed the boolits come out shiny and soft but the drive bands are sharp and well filled out.
I think that one side of the small lyman mold might be cooling off like Ian is talking about [handles act like a heat sink]
I know the 435gr 2 cavity aluminum LEE 45-70 mold I have needs that speed because it does cool off quickly.
the one benefit is that they both produce a huge pile of boolits quickly.
KHornet
Well-Known Member
Like Fiver, I have some Iron molds including 449 that wants to be cast fast and hot. Have also a single banger 449 HP that Buckshot did for me years back. Once it is very hot, and kept hot produces a ding-How(Chinese for very good) bullet. Once I get my timing right with the HP, I can get between 2 & 3 a minute, and maintain that pace for maybe a half hour. That produces a sufficient quantity to hold me for quite awhile. Killed my last two deer with it.
The sprue cutter can swing free if bumped with finger. I have smoked mould with wood match. fiver..yes the unfilled bands are greyish in color and grainy looking. I did very lightly break top edge of blocks for under sprue cutter air release. The base is perfectly filled out with razor sharp edge..as well as nose. I had cleaned blocks in very hot water with Dawn..might have to clean carefully again. Temp. was from 680-750 deg...having to wait quite a bit for sprue to harden..tried casting faster at this temp by resting cutter on copper block for heat sink..all helped some but still rounded at edges. Thanks all for advice.
Ian
Notorious member
Bingo! You have a mould temperature problem. What's going on is you're running your mould in the "awkward stage" of temperature, too cold for a light satin frost all over and too hot in certain spots (where you see the whitish crystalliney rounded parts) for shiny bullets. For some reason I always notice that type of defect beginning on the edges of the lube groove/driving band intersection. I'd recommend first trying that mould again with no modifications and just cast fast (at least four complete cycles per minute for five minutes straight after it's up to the temperature/pace you normally make and see if you can't get those bullets frosty all over. Once they get frosty all over (takes a couple minutes of them cooling on a towel to notice it) the bands will start to fill out fully again. If you can hit the sweet spot on the low side of frosted band edges and still get good fillout and no wrinkles (difficult to do with many alloys) then try that too.
Here's a picture from the web that shows exactly what I'm talking about, bullet on the left. Do yours look like that one?
fiver
Well-Known Member
that's what I was picturing too.
my HM-2 9mm mold does that and if I just cool the mold down or power through it and cast just a little quicker things settle down.
with that mold it's easier to increase the pace for a few pours then start the cruise from that point onwards.
the boolits come from the mold shiny and perfectly filed out then turn grey as they cool.
my HM-2 9mm mold does that and if I just cool the mold down or power through it and cast just a little quicker things settle down.
with that mold it's easier to increase the pace for a few pours then start the cruise from that point onwards.
the boolits come from the mold shiny and perfectly filed out then turn grey as they cool.
James W. Miner
Active Member
I can not find a picture of that boolit. If it has small grooves and bands like a Lee, you have a HOT spot where the bands do not fill. Any frost will tell you but if bands are shiny, it is a lack of heat. Either direction is a problem.
Bret4207
At the casting bench in the sky. RIP Bret.
Always remember pot temp and mould temp are 2 different critters. Pot temp you control with the pot thermostat and has relatively little to do with mould temp as long as it pours smoothly. Mould temp is controlled by casting tempo. The more often you put hot lead in the mould, the hotter the mould gets. The more time the mould spends empty the cooler it runs. Stop looking at the castings and get it in gear and get that mould up to proper temp. See if you can get some frosting starting, then you know it's HOT. Hot moulds almost always give better castings. If this doesn't work, then look at venting and more cleaning, etc. IME if you have to let the alloy run over the sprue to get good fill out, the mould is too cool. I'd rather have to wait a few seconds for the mould to cool or "BruceB-it" with a damp cloth than have incomplete fill out.
A wise man once said . . . 
This is solid advice to follow. If you run your pot at 700 degrees your alloy is at a minimum 100 degrees over full liquidus temp and a good place to be, easy on the tin in your alloy and pours quite well. It is also at least 300 degrees hotter than your mold needs to be. If your not keeping your mold hot enough with an extra 300 degrees you need to stop taking lunch breaks while casting. Or as a wise man once said, stop inspecting your new creations with the empty mold hanging open cooling quicker than you might believe especially if it's aluminum.
.
This is solid advice to follow. If you run your pot at 700 degrees your alloy is at a minimum 100 degrees over full liquidus temp and a good place to be, easy on the tin in your alloy and pours quite well. It is also at least 300 degrees hotter than your mold needs to be. If your not keeping your mold hot enough with an extra 300 degrees you need to stop taking lunch breaks while casting. Or as a wise man once said, stop inspecting your new creations with the empty mold hanging open cooling quicker than you might believe especially if it's aluminum.
.
Ian
Notorious member
So true.