sprew plate hole diameter

[stumpjumper]

has any one opened up the sprew plate hole to a bigger diameter on big grain boolits? and if you did, did you open up the hole on the ladle too? ive got a few 4570 moulds and im still strugling to get good fill. ive run the melt tempature all the way up to 875 or a little higher. I cant seem to get the hang of this. i read a article in bpcr news where someone was makeing vented sprew plates. anyone heard of this. thanks Dave

[Bass Ackward]

has any one opened up the sprew plate hole to a bigger diameter on big grain boolits? and if you did, did you open up the hole on the ladle too? ive got a few 4570 moulds and im still strugling to get good fill. ive run the melt tempature all the way up to 875 or a little higher. I cant seem to get the hang of this. i read a article in bpcr news where someone was makeing vented sprew plates. anyone heard of this. thanks Dave


Yes and Yes.

But before you do, try smoking your mold no matter what material it is made out of. See what happens. You can also take a file to and ever so lightly put a bevel on one or both sides of you blocks. Ventilation is ventilation no matter whether it is there or the plate. But I am talking light, like just breaking the sharp edge.

[montana_charlie]

Well, Dave...
Some people enlarge the hole in the sprue plate, some open up the ladle. Some do both.
But, generally speaking, I trust the manufacturers (of both items) to have figured out the right dimensions long before I bought the hardware.

You didn't actually specify what results you are getting...just voiced the fact that things are not the way you want them.
What is it about your bullets that displeases you?

Since you are asking about venting the sprue plate, I guess your bases don't come out with sharp corners. Is that a correct assumption?

If so...
- Are you holding the dipper nose tight to the sprue plate...or leaving a crack for air to escape?
- Are you (at the end of the pour) leaving a generous puddle of molten alloy on the sprue plate before taking the dipper away?
- Does the puddle harden right away...or take four or five seconds to solidify?

How tight is the pivot screw on your sprue plate?
I set mine so the spring washer is providing the downward pressure...not the head of the screw. Things are just tight enough that the plate won't swing open under it's own weight.

If (after checking or adjusting the things above) you still don't get a sharp corner on the base, you can vent the sprue.

Using emery paper on a flat surface (like a file), or a fine whetstone, or a jeweler's file if you have a light touch...break the top corners of the mould halves between the sprue hole and the edge of the blocks.
You only want to remove enough metal to make the corner 'shine' a little...not enough to see an angle on the corner.

You can start out by only doing one mould half. If the groove that creates doesn't seem to be enough of a vent, do the other half.

When finished, you should be able to 'see' a shallow groove when the halves are brought together, but it should not be deep enough to catch your fingernail.

If you still don't get good bases, DO NOT remove more metal. Something else must be causing your trouble.

This is an irreversible action. If you want to talk about it first, that would be wise.
CM

[Buckshot]

...............Bigger fill holes in the sprueplate can make it difficult to cut, and possibly difficult to cut flat. If the blocks are clean and correctly vented, the alloy and mould is up to temp there are 2 remaining variables. How does the cavity want the lead admited, and does the mould drop better boolits sooted or not. HAve the above and finding out the last two should have you producing good boolits.

................Buckshot

[omgb]

Dave, here's a tip that may solve your fill problem. Get your metal up to temp and get the mould just as hot. If you have a bottom pour pot, press the sprue hole up tite to the spout and fill. As the mould reaches full, back off the mould a tad and let a large puddle of melt flow over the plate. This usually does the trick. If you are using a ladle (Lyman or RCBS) hold the mould at 90 degrees to upright. Place the spout of the ladle into the sprue hole. Rotate the entire unit to upright. Allow metal to fill the mould under "head" that is to say, the weight of the metal in the ladle. Just as the mould reaches full, back out a tad and let the over flow go all over the top of the mould.

Either of these tricks will get a good fill provided the mould is hot enough and there are no blocked vent lines etc.

[chunkum]

Adding tin to any alloy up to 3.0 - 3.5 % helps with fill out of large diameter heavy bullets. (for practical purposes this can be 1oz of tin to 2# or 32 oz of alloy). A pair of large bolt cutters works well on long strip-type tin ingots along with a pair of grocery scales to find that correlation of length to weight This along with the additional heat you've already tried will often get those pesky sharp corners filled out as they should be. One thing I've found recently that makes a big difference when using a bottom pour pot is keeping the pot full of alloy and avoiding trying to continue casting down to "the last drop". In retrospect, this seems an obvious thing to do, giving higher fluid pressure in a "direct pour" and a faster flow rate with either a direct (contact with spigot) pour or a "drop pour" (a slight distance from the spigot to the mould). Some pots are adjustable for flow rate and, of course, the spigot has to be kept clean and free flowing to maintain the maximum optimal flow rate.

If you are using a Lyman single cavity mould, there are two sizes and since the smaller size cools off faster, then a little faster casting pace helps to keep it up to a higher temperature more conducive to a full "fill out" of the mould. I use a hot plate to get the mould up to temperature when I start out and sometimes use it again if there is some outside interference with keeping the cadence of casting at the best rate. I hope these small nuances and modifications will help you resolve the difficulty of full fill out of large diameter, large cacity moulds.
Best Regards,
chunkum

[stumpjumper]

goodmorning. i guess i should have given a little more info. my base is filling out it is around the lube grooves in the middle of the bullet im not getting good fill.it is not always in the same spot either. ive tried holding the mould in line with the ladle and turning the hole mess upright then i tried ladleing to the mould with mould upright. i do leave a lot on the sprew plate when i pour. i cleaned my moulds and smoked them with stick matches. i used carborator cleaner to clean the mould is that ok. what does everyone else use. im use 20 pounds of pure lead with 1 pound of tin. dave

[montana_charlie]

it is around the lube grooves in the middle of the bullet im not getting good fill.it is not always in the same spot either.
If the mould is clean (and that can be deceiving) your problem sounds like the mould is too cool. Your alloy has plenty of tin to get total fillout.

You should not need your alloy above 800° with 20:1, but we don't know if you are using a thermomometer, or just the markings on the control.

Your dipper technique (one of them) sounds about right.
Mate the nose to the sprue plate and rotate the whole thing upright.

I don't hold them together very tightly, so as not to press the sprue plate against the mould top any more than necessary. That allows air to escape (under heat pressure) between them.
Rotate the assembly in a smooth motion that uses (perhaps) two seconds to complete. It does not need to be done suddenly.

Immediately on reaching the upright position, tilt the dipper to one side just a tiny bit. When the cavity is full, lead will start to leak out of the 'crack'.
Slowly open the 'crack' to adjust the puddle. At that point, you can take the dipper away...or just let it empty over the sprue plate and run off.
Do not hold them together so long that the lead in the dipper nose freezes.

I hold the mould straight up and stationary until the sprue freezes, while laying the dipper back on the alloy to stay hot.

As for your mould being clean...
I had a mould that would not cast without 'wrinkles' in the bands. Tried absolutely everything, including smoking the cavity. When nothing helped, I started over by cleaning the mould...again. This time I used an ultrasonic cleaner (which got it truly clean), and the mould worked perfectly after reassembly.

So, you can believe it is perfectly clean, but looks can be deceiving.
If you use lube on the mould be stingy with it, and absolutely certain none gets in the cavity. I don't even allow any to get on the mould faces.

People talk about smoking a cavity as though it is a necessity. I say that a good mould doesn't ever need it.
Those that do benefit from smoking need it to help get the bullet out (IMO)...not to make it fill the cavity.

I have smoked moulds in the past...when I thought it was a standard requirement for bullet casting...but I don't have any moulds (now) that need it.
If your bullets (wrinkled or not) fall out easily, try going without the smoke...and concentrate on clean cavity, mould temperature, and technique.
CM

[chevyiron420]

dave, i had been having alot of trouble with this, and the kind people here helped me out alot. if the folks here could see the bullets it will help. i cant post pics myself and it made things harder because band fill out can be caused by many things, some the oposite of each other. anyway, are your bullets frosty looking in the areas that are not filled out? if so, you may be doing the same thing as me, running the melt and or the mold too hot! i dont have a thermometer so i had to do alot of experimenting with the pot temp control, and the casting speed to fix the problem. i have more trouble with aluminum molds with this, and its harder to keep an eye on you bullets if your water droping like i do. i started droping a couple on a towel about every ten so i can look em over. as soon as i see some frosty spots i have to turn the pot down a little, and hold the mold open a few seconds and blow on them. anyway, without a thermometer you have to read the bullets to see what you need to do. normaly a bullet not filled out due to to low of a temp will be shiney and may have wrinkles and too hot will be frosty. each mold will have a sweet spot, so make notes on what works with each one. try making some boolits with out being concirned about them being shootable. drop them on a towel so you can look at them easeyer and dont throw any back in the pot, so your temp will not be affected by the cool sprus or bullets, and experiment till you get it.--phil[smilie=2:

[Bullshop]

An unfilled spot or area in the middle could be a couple different things. Most common would be some sort of contamination and or in conjunction with poor venting at that point.
A common practice that can cause this problem is to apply preservative for storage to the mold while the mold is still hot or even warm. It causes the preservative to penetrate below the surface and so is much harder to clean off completely. In this case boiling in dish water will work far better than carb cleaner.
Another contributor to this problem is a plugged or inadequate vent line. In this case smoke only makes it worse. Complete and adequate venting around the entire cavity will I believe eliminate such problems. When I encounter a persistently problematic spot in any new to me mold I will take steps to improve venting at that point. At times venting that problem spot will cause the spot to shift to a different point that has the least free venting. At that point the process is continued until the entire cavity has free venting and the problem is gone, for good. Pouring faster cant help but actually causes the problem. When the cavity is filled instantly air has to be pushed out the vents. If it can not be vented out while the alloy is fluid you get voids. Having a small amount of contaminant as lube or preservative in the cavity compounds an inadequate venting problem because the super heated contaminant is burning and producing expanding gases just as burning powder does in a barrel.
To eliminate any venting problems there are a couple things I do. First I NEVER smoke a cavity as I think it just helps to plug vent lines. As for working the cavity, a small jewelers 3 corner file is used to put a very light bevel on top of the blocks at the parting line. The same thing can be done to the sprue plate at a 90 degree angle to the parting line. That will get a well filled base. For the internal cavity vents I use an exacto kit with several different changeable cutters to open all vent lines completely from the cavity to the outer edge of the blocks. Yes this is slow and tedious but remember it is a one time fix and solves the problems for good. After opening any vent lines I use a type writer eraser pencil to polish off any burrs that may have been raised to the edges of the cavity, and to the length of the vent line.
Now once you have that cavity clean and breathing freely pour as fast as you want. You should never have that problem with that mold again. You may even find that you can cast at a lower temp than you were ever able to before. Granted these are my thoughts and observations derived from my own experience and not documented fact proven in the lab. Consider this though that I have had to battle these same problems in trying to make my living. I think I have had far more incentive to eliminate such problems and to speed up high quality production than 99% of those here. Thats the way I do it and it works for me. Usually there is a right way, a wrong way and then there is always my way to do anything.
BIC/BS

[Bass Ackward]

To eliminate any venting problems there are a couple things I do. First I NEVER smoke a cavity as I think it just helps to plug vent lines.
BIC/BS


Dan,

I smoke right off when someone is having a problem. It's an easy to clean up, down and dirty way to check if it's your mix or the temp. What made me suspect is that fact he said a "few 45 cal Molds". Very unlikely they are all a problem.

He quoted his temp as if he was measuring it. When I got my thermometer, it was off by almost 150 degrees. If it ain't his mix or temp, then it's most likely casting rate or he adjusts his sprue plates too tight. My guess.

[stumpjumper]

hello, i thought i would give you all some more info. i was using a thermometer. and my lead was from a plumbing supply place, pure lead. and used solder for my tin. and far as tempature after just a little bit my bullets were frosty looking so i would assume the mould and lead was up to speed on tempature (maybe to much). anyway im going to back up and try a few things on here i read. start by cleaning my moulds again and the vent lines. also i just picked up my first bucket and a half of wheel weights, i ordered a lee 358-158- swc 6 banger a while back. and i cant wait to try it out. i will report back with my results some time next week. thanks to all who replied. have a great weekend. dave

[omgb]

When you clean your mould, try this. If this is an iron mould, take a bore brush, (bronze of plastic bristle) coat it with tooth paste of Bon Ami, chuck it in a drill and close the mould on it while the drill is turning. Do this a few times and then clean with brake cleaner. Now if it's an aluminium mould, the only brush you dare use is a bristle brush. Nothing more abrasive than tooth paste either. just sping by hand and be gentle. Clean as before. Get it to the point of making the bullets frosty and have at it.

[AZ-Stew]

stumpjumper,

I didn't see this thread when it started, but please allow me to throw in my $0.02.

I have opened up sprue plate holes, specifically to cure the problem I believe you're describing. I don't use a dipper, though. I use a bottom pour pot, and I have opened up the spout on the ones I've owned to allow a faster pour. I use the "drop pour" method, allowing some space between the spout and the sprue plate when casting.

I, too, had issues with voiding in the bullet bases when I first bagan casting many years ago. This was caused by alloy shrinkage during cooling of the cast bullet. Unlike Montana Charlie, I believe the high-volume commercial mould makers (Lyman, RCBS, Lee, etc.) lean toward a philosophy that favors the bottom line, rather than optimizing each feature of the mould to the bullet diameter being cast. Simply, it's cheaper to make and manage the inventory of sprue plates with one or two opening diameters than it is to optimze the openings specifically for each particular bullet diameter and weight, then manage the inventory of a dozen or more different sprue plates. Additionally, for hard alloys, such as Linotype, smaller sprue openings make sprue cutting easier, so the casual user enjoys easy mould operation. This equates to "quality" for many users. Generally, I find the factory sprue openings too small for most handgun bullets, especially those over .40.

Alloy shrinkage as the freshly cast bullet cools requires a reservoir of still-molten alloy to draw from to prevent bullet base voiding. As the bullet in the cavity cools prior to sprue cutting, the last part to solidify is at the center of the bullet base. Shrinkage will cause a draw-down of whatever is in the sprue plate opening. This is why you need to leave a generous puddle of molten alloy on the sprue plate after filling the mould cavity. If there's plenty of alloy there, the shrinking material inside the cavity will pull from it and ensure a void-free bullet base. If you leave a puddle of alloy on the sprue plate after filling the mould cavity, you'll see the surface of the material sink at the location of the sprue opening just before the puddle solidifies. This is the draw-down I've mentioned. That material is being pulled into the mould cavity as the bullet inside cools. If the sprue plate opening is empty, as it would be if you hold your dipper on the plate and pull it just as the alloy starts to harden or if you don't leave a good puddle of metal on the sprue plate when using the drop pour method, the shrinkage of the metal in the cavity will still draw-down, but now it will be drawing air and result in a voided bullet base and a light and possibly out of balance bullet.

I enlarge the sprue holes in moulds that exhibit base voiding to ensure that they will have a large cross section of molten alloy above the opening (from the puddle of metal I overflow onto the sprue plate at the end of the cast) to draw from during cooling. Smaller bullets usually work with the factory size small sprue openings, but larger bullets may require larger openings. I've never had this technique fail to resolve the voiding problem.

Cutting the larger opening requires a machinist's countersink, a drill bit larger than the original sprue opening (start slightly larger and increase the size until the voiding ceases), a drill press and a vise mounted to the drill press table. After completing the cuts with the drill and countersink, use a large stone or some 400 - 600 grit wet/dry paper over a flat, rigid surface to de-burr the bottom side of the sprue plate.

Regards,

Stew

[piwo]

Can you leave your moulds soak in "carburetor cleaner" overnight, or is this solvent too aggressive on the steel?