moulding wads?

[Hogtamer]

seems like some creative soul could come up with a wad custom designed thusly: a non discarding plastic wad that would snap into the cavity of a lee key drive slug (sort of 2 half-moon convex base in wadcup)that would provide support for the slug, petals of a proper thickness and height, and of course a good OP base appropriate for a straight wall hull. mmmm.....the petals would have to shear off to allow the slug to fly downrange....looks like a challenge some engineering type would love!

[Teddy (punchie)]

I've thought about that before , using some type of plastic cup or patch to use for loading. Plastic cut into strips using a wooden dowel rod and tie the tops. Heat bottom with a extra ( one or two) cut out circle(s) until it just melts and start in form from underneath, use a stick to roll the melted edge. Should make a nice cup. Not sure what plastic can do this, bleach bottle?? Cards out of heavy paper, or card board press flat using a leather punch.

[turbo1889]

The only homemade wadding components I've messed with were cellulose fiber based rather then plastic based. They do work but are a lot of time and effort expended into making them.

Plastic (either petro or ester based) wadding components construction and molding I think is pretty much beyond the tooling and capital expenditure capabilities of most hobbyists. If you had a half mil or more just lying around you didn't need to drop into equipment, then maybe.

[longbow]

I use forms made from CPVC pipe to mould attached wads from hot melt glue with "reasonable" success. These are cast right onto the slugs. I have had some work very well but as usual consistency is the issue. It is hard for the home craftsman to make something that will produce a consistent product that requires tolerances withing a few thousands of an inch... at least within reasonable limits of time and effort.

My goal was to produce a home made AQ slug which sort of worked but attaching a "skirt" to a round ball (AQ's actually have a flat base) was a problem due to the swaging/shearing against the spherical surface. So I made a mould to produce a TC flat based solid slug. This works fairly well but getting the skirts absolutely consistent and slug/wad combo right is a challenge.

I have also made a form to add a hot melt glue skirt to the Lee Drive Key slugs and first time out got roughly 6" groups at 50 yards and recovered slugs had obturated evenly so it all looked pretty good. Second time out things didn't go so well. Also, since I can get pretty dependable 3" to 4" groups using round balls out to 50+ yards, it is a lot of work to add a skirt to the Lee slug to get 6" groups at 50 yards. Maybe the Lee slug + skirt would have given better longer range accuracy than the round ball but at 6" at 50 yards, doubtful.

Now, last time out I had used a lighter load so I didn't pound myself senseless again shooting dozens of slugs from the bench but recovered slugs indicated that obturation was not there so I think the load was too light ~ not a powderpuff load but not enough to cause even obturation.

Short story... I am working on the Lee and other "Brenneke" style slugs. It is slow going lately though. Need more range time.

Longbow

[dverna]

http://www.easyplasticmolding.com/

Here you go. You still need the ability to machine the mold for a "production" setup but you could use an epoxy mold for small test runs. Epoxy molds are relatively easy to make and do not require machining.

There is also some stuff on making your own plastic injection machine if $600 is too much. Just be careful. Plastic is hot and will give you a nasty burn.

I used to manage a plastic injection molding company and thought about doing something like this but it would turn a hobby into a job. My last patent cost over $10,000 and that would require the sales of a lot of parts. Maybe if I get bored with retirement. LOL

Don Verna

[turbo1889]

http://www.easyplasticmolding.com/

Here you go. You still need the ability to machine the mold for a "production" setup but you could use an epoxy mold for small test runs. Epoxy molds are relatively easy to make and do not require machining.

There is also some stuff on making your own plastic injection machine if $600 is too much. Just be careful. Plastic is hot and will give you a nasty burn.

I used to manage a plastic injection molding company and thought about doing something like this but it would turn a hobby into a job. My last patent cost over $10,000 and that would require the sales of a lot of parts. Maybe if I get bored with retirement. LOL

Don Verna

Very interesting, I had no idea you could actually get a plastic injection molding machine for such a low price. Granted single cavity low production rate but still. The one thing I noticed right off though is that it appears to be low temp plastics only 490-degrees max melt temp. I wonder if such low temp is suitable for shotgun wadding use or if it would burn/melt because it couldn't take the temp. I've always wondered what plastic exactly they make different shotgun wads from, there are obviously different plastics used for different wads even a guy like me with hardly any plastic knowledge can figure that one out just messing with different wads.

Also, I wonder if those machines can handle the bio-degradable soy-bean-oil based plastics or not? Would be a nice plus since I for one would prefer not to spread non-degrading colored plastic litter around my hunting grounds every time I pull the trigger. Granted if a regular plastic wadding component is what is needed then I'll use it but where possible to substitute for a bio-degradable solution without compromise of performance I certainly prefer to do so especially if they aren't range loads but out in the wilds loads. Not that worried about lead actually since it comes out of the ground and goes back into the ground where it came from in nearly the same form as it was originally mined (you will find natural nearly pure lead placer deposits as well as lead bearing ores) but most plastics on the other hand doesn't go back into the ground where it came from quite so easily and many of them its thousands of years or some such crazy thing before that stuff goes back where hence it came. I kind of like to go out into the woods and not see a bunch of litter junk all over and I've seen some popular bird hunting areas where its not just a carpet of grass your walking on but a bunch of plastic wads and hulls as well litter junk like a trash dump and it sort of wrecks the whole experience when your hunting area starts to look like a trash dump instead of the wild outdoors.

[longbow]

I wouldn't worry about temperature so much as self lube capability. Even paper patching doesn't burn in smokeless rifle loads. The time the plastic is exposed to the heat is such a short time it should not melt... unless there is blow by. I have seen wads melt due to gas blowing by the seal or in the case of using shotcups with no plastic gas seal over card wads. I think that is more like gas cutting though as normally there is no melting plastic of the seal.

I should probably have added the fact that I use my hot melt glue wads mostly for wad slugs (inside shotcups) so the glue never contacts the bore.

I have also made paper tubes for the glue wad or paper patched full bore slugs with glue skirts to prevent glue form contacting the bore.

Ideally the attached wad would be a material that would both seal and slide down the bore easily without distorting badly.

While those little injection moulding systems are pretty slick I would be hard pressed to make any quantity of wads using one. It would be fine to prove an idea then make up a few for sighting in and hunting but picture going to the range or gravel pit with 50 to 100 rounds and burning them up in an afternoon. Too much work for me!

I think it would be quicker and easier for me to buy some 3/4" plastic rod (nylon, Delrin, or whatever), drill as deep as I can with about 3/6" bit, turn the OD to 0.729" then part off discs the length I want for wads than it would be to injection mould wads with one of those little units. However, I am too lazy to machine all my wads too!

Longbow

[Cap'n Morgan]

I have been thinking about making a mold for polyethylene wads for my slugs, but it seems as overkill at the moment. Making a mold for a non-compression, smooth sided wad is not a problem. Having ribs or belts on the inside of the wad is also possible, but any outside profile other than smooth - or perhaps straight ribs - will need a more complicated slider mold to produce. The easiest solution would probably be to contact a plastic injection molding company and buy a discarded, obsolete mold, modify the mold and have the company run a couple of thousands wads for you.

The temperature of the hobby molding units are more than enough for melting polyethylene (high-density polyethylene has a melting point of 250 to 350 °F), but I am not sure a drill press will create enough pressure for filling a thin walled shape like a shot wad. Most plastics has a high viscosity even when melted and need high pressure to fill thin walled cavities.

For now I will concentrate on epoxy resin wads as the molds are quite easy to make and modify.

[turbo1889]

I skipped right over their $600 drill press machine and went straight to their $1,500 full unit that is built sort of like an upside down reloading press and would probably have the leverage needed and is capable of 3-casting cycles per minute or up to 180 casts an hour (call it a 100 an hour is a good realistic estimate) which isn't that bad of a production rate if your just making them for yourself, not to mention you can cram as many cavities inside the largest size mold block as possible to maximize your production per casting cycle.

The first thing that came to my mind was a simple mold that would cast simple 0.410" diameter plastic cylinders (as many as will fit in one mold block together arranged in rows on the sides and bottom with a center feed sprue) an inch long with a hollow in one end that was 0.355" diameter and about the same amount deep and you would just put a drop of glue into that hollow and then press in any 9mm-357-caliber pistol boolit of your choice to form the head and you instantly have a 410-bore Brenneke slug with attached tail.

Oh, yah, as to "burning paper" vs. "melting plastic" you have to have free oxygen available for paper to burn not much of that available inside of a gun barrel during the firing sequence. Powder has its own oxidizer built in and probably isn't going to give much if any of it up to to paper. Plastic on the other hand just has to have heat to melt. I have experienced melted plastic inside of a gun barrel when I tested some rapid prototyping machine made tails for 410 slugs a few years back, it was some black plastic stuff that coated the inside of my barrel with goop and the next batch the guy made them out of a different white plastic and the second batch didn't have the same problem. So if you get the wrong kind of plastic it can cause melted plastic barrel deposits.