Any idea how I bent my sprue plate so I dont do it again?
I can't think how it would have happened. It's a 4 cavity brass mp mold in h&g 68 200gn swc. Only a week's old. Used in maybe 5 sessions.
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Any idea how I bent my sprue plate so I dont do it again?
I can't think how it would have happened. It's a 4 cavity brass mp mold in h&g 68 200gn swc. Only a week's old. Used in maybe 5 sessions.
What do you use to strike off your sprue plate? A good whack at the wrong angle, or a session of such, could bend the thing, especially if the mould isn't up to full heat and all four cavities have solidified and hardened.
I generally tap on the sprue plate such that it takes maybe two or three taps at first to get the sprue cut; this on a single cavity mould. When it is up and running, one tap at the same force is enough to cut the sprue. My only four cavity moulds are Lees, and I warm them for a while by only pouring two cavities, then three, until the cutoff "feels" right. Then I go to four, and have no trouble.
You can straighten a sprue plate, but it's kind of tricky sometimes. I would recommend getting a new on from mp, practicing straightening on the old one, and keeping it in reserve.
dansedgli, welcome to the forum,Quote:
Originally Posted by dansedgli
Once I learned to pre-heat a mold and use a gloved hand to open a sprue plate, I never ever again have 'hit' the sprue plate with any tool or stick.
With that said, I am thinking, that once a Sprue plate is bend...I think the average fella with a hammer (I include myself in this group) will have ZERO success straightening it out...Time to buy a replacement.
NOW, if the sprue plate is warped from over-heating, instead of bent from WHACKING it, then maybe you will have some luck using sandpaper and a flat surface (like plate glass) to sand-out the warp.
Good luck,
Jon
A sprue plate can be straightened but as said its a tricky job. Check it carefully to find the bend and be sure which direction its running. If you have a small arhbor press It can be gotten close pushing it flat between 2 heavy flat plates of steel. You can also do this step in a heavy vise clamping the sprue plate between the heavy plates. This sometiomes works better since the plate can be left clamped for a period of time to help overcome spring or memory. Heres where it gets tricky at times is the over bed needed to take out the last little bit from spring or memory in the steel. I normally stat with .010 shim stock under each end and a piece on top of the bend between the heavy plates and over bend it that much and see what it takes out. I then keep adding to it till its as flat as possible then with a very flat stone or sand paper opn a flat surface resurface it to dead flat. If the straighting is done right only a very few thousandths will need to be removed. If your using a mallte to cut sprues use a light straight thru tap to do it, more of a push thru type swing. I perfer a small dead blow hammer or cap hammer in the 5 oz to 10oz weight range ofer the traditional dowels and hammer handles. The plastic no mar dead blows and cap hammers dont ding or distort and with a stright thru swing do a good job.
The sprue cutter probably isn't bent, it's probably the block at the hold down screw that's damaged.
If you loosen the hold down screw and look at it with a light behind it, you'll more than likely find it sets flat.
Jeff
Bingo!Quote:
Originally Posted by JonB_in_Glencoe
I buy more than a few used molds and BOY!! - The stick, the hammer, the mallet or what have you sure takes its toll on well made molds! Some are ruined for ever. Wacking molds maybe the #1 reason for misaligned mold halves. If I can determine if the former owner is a mold wacker I just pass on the used mold.
Correct metal temp., hot mold and a good pair of gantlet welders gloves get the job done on every mold I own regardless if a one or 6-Cavity mold. Learn how by doing it and save your molds accuracy.
BTW- In addition to good gloves, a metal thermometer and a full face shield complete the deal.
Thanks everyone. My first session I used the mallet but purchased a stove top and have used a glove since.
Mass caster is on the money. There is damage to the brass under the sprue plate at the hold down bolt. I mustnt have been lubing correctly.
I must admit in the last 2 sessions I didn't put lube near the bolt as it kept seeping into the cavities.
What is the correct method to lubing that area? Do I need to remove the bolt each time? Does the lube need to be reapplied often? I might have done 250 sprue openings between lubes when i noticed the bullet bums were protruding above the mould at the opposite end.
Is aluminium less likely to have these issues?
You have the top plate on too tight. It should swing free - just barely. Galling even with the best molds happen with the top plate (sprue plate) on too tight. Lube becomes much less of an issue.
"Is aluminum less likely to have these issues?"
More.
Thankyou Chill Wills. Maybe I should have cut my teeth on a cheaper lee mould.
I will order another one.
Don't give up on your mold so fast , it's probably not so bad that it can't be fixed . Go to the mold maintenance and repair section and do a little research you will probably be able to fix it up it a few minutes . If you figure out how you broke it you can figure out how you can fix it ,
A picture is worth a thousand words. If we could see the mold, we could offer up some advice.
I bought a 40 cal Lee 6 cav mold that had the issue you have.
Luckily Lee puts the bolt holes on each end of the mold (for sprue pivit and sprue stop) in the same location, but opposite. So I was able to remove the bolts and clean up the galling, then reverse the Sprue plate...and solved the problem. I'm not sure if that'll work on a MP mold or not? Maybe there is another simple solution?
The mould is not a loss. Simply flip the sprue cutter & hold down screw to where the stop screw is, you have good metal there.
Great idea, thanks guys.
There is a split pin in the opposite hole but I should be able to tap it out to suit the bolt and reinsert the split pin in the original bolt hole.
I'll post up some photos tonight when I get home. I did a fair amount of reading last night and learned some new things so hopefully this won't happen again.
I think you will do well as a caster. You have the right "can do" outlook.
I learn the fastest when I wreck expensive equipment. :???:
I tapped an M6 thread into the roll pin hole at lunchtime and tapped the roll pin into the original pivot bolt hole. The problem appears to be fixed.
I have no set screw hole on the pivot bolt anymore but that is ok. I'll drill and tap another hole for the grub screw if that becomes an issue.
Here are some photos of the damage (now around the roll pin) and the fixed result. The mold is covered in heaps of oil in these photos.
http://i140.photobucket.com/albums/r...psobx37ul2.jpg
http://i140.photobucket.com/albums/r...pshotdk10h.jpg
http://i140.photobucket.com/albums/r...ps8lcvavkx.jpg
My next task is to get rid of the smear marks and tinning inside the mold (that I learned about last night) and smooth out the sprue plate at the fill holes. I can feel them catch on top of the mold in some spots.
Nice job! You have some skills so you are doing well.
Just a thought.
If the old galling gives you trouble, you can remove the roll pin and remove the top plate and give the two mating surfaces a light workout on 320 wet/dry (but as I think you know) use a flat surface. I use a my old layout table. Surface ground cast iron from the 1940 - not my Granite.
Don't go with a finer grit. The marks help let the air out when casting. Up to 320 is plenty smooth and even 240 is great!