Author Topic: Casting balls (Bondo) (Read 1990 times)

Blaster · « **on:** June 12, 2012, 06:00:53 AM »

Help!! I had recently cast some 2-inch lead balls for firing in a mortar with a 2.25-inch bore with a 5/8-inch chamber. These balls weigh right at two pounds and maybe even a couple ounces over the 2 pounds. The mortar that will fire these will be a professionally made one from South Bend Replicas, their Coehorn, weighing about 50 pounds with a cast iron sled base as pictured in their catalog. I started to really wonder if these 2 pound LEAD balls may be just a bit too heavy which could possibly test the safety/integrity for this mortar. Have been firing some of the small drink cans filled with concrete and some of the 2-inch electrical conduit projectiles also loaded with concrete.
I have been convinced that balls cast of Bondo would pretty well eliminate the safety concern. I know zink is even better than Bondo but that will require melting and casting which I do NOT want to mess with and that eliminates zink. So - Bondo it is! My question is how do you get the Bondo to flow "EASILY" and consistently through the sprue holes in the mold which is an aluminum mold as pictured below. Am aware that the mold must be coated with perhaps machine oil to avoid having the balls stick in the mold cavity. I have never messed around with Bondo thus the reason for my questions. Many thanks!

Zulu · « **Reply #1 on:** June 12, 2012, 09:24:28 AM »

Quote from: Blaster on June 12, 2012, 06:00:53 AM

Help!! I had recently cast some 2-inch lead balls for firing in a mortar with a 2.25-inch bore with a 5/8-inch chamber. These balls weigh right at two pounds and maybe even a couple ounces over the 2 pounds. The mortar that will fire these will be a professionally made one from South Bend Replicas, their Coehorn, weighing about 50 pounds with a cast iron sled base as pictured in their catalog. I started to really wonder if these 2 pound LEAD balls may be just a bit too heavy which could possibly test the safety/integrity for this mortar. Have been firing some of the small drink cans filled with concrete and some of the 2-inch electrical conduit projectiles also loaded with concrete.
I have been convinced that balls cast of Bondo would pretty well eliminate the safety concern. I know zink is even better than Bondo but that will require melting and casting which I do NOT want to mess with and that eliminates zink. So - Bondo it is! My question is how do you get the Bondo to flow "EASILY" and consistently through the sprue holes in the mold which is an aluminum mold as pictured below. Am aware that the mold must be coated with perhaps machine oil to avoid having the balls stick in the mold cavity. I have never messed around with Bondo thus the reason for my questions. Many thanks!

Blaster,
Why not pour them out of cement? I do it all the time. 1/2 Portland, 1/2 sand and mix enough water so it flows easily. After I pour, I rod it with a piece of wire to help eliminate air bubbles and let it sit for 12 hours.
They turn out pretty nice but I'm only doing it for display. I don't know how they would shoot.
Zulu

Blaster · « **Reply #2 on:** June 12, 2012, 10:58:20 AM »

Those concrete cannon balls are quite attractive but I wonder how they'd hold up when actually being fired without being held together with metal like the cement filled beer/soda can projectiles.

Zulu · « **Reply #3 on:** June 12, 2012, 04:00:05 PM »

Quote from: Blaster on June 12, 2012, 10:58:20 AM

Those concrete cannon balls are quite attractive but I wonder how they'd hold up when actually being fired without being held together with metal like the cement filled beer/soda can projectiles.

I'd bet they do better than bondo.

Zulu

shred · « **Reply #4 on:** June 12, 2012, 04:08:48 PM »

Bondo is pretty strong stuff when mixed and cured properly. We'd mix in a bunch of sand and make fake-rock climbing holds that held up to tremendous use and people dangling from them all day long (actually we ditched the Bondo and went to poly resin and filler-- much cheaper and works as well)

The downside is it doesn't pour rapidly. It will fill every crevice perfectly if allowed to flow and set.

Frank46 · « **Reply #5 on:** June 12, 2012, 05:00:24 PM »

Seems we now have three types of balls. Steel, lead, and BONDO balls. Wonder how they would hold up on firing. Frank

gunsonwheels · « **Reply #6 on:** June 12, 2012, 05:42:23 PM »

Cement sounds like an interesting idea. I know the redi-mix outfits around here run their trucks out with both steel fibers (look kinda like one leg of a bobby pin but wire instead of flat) and also glass fibers. I personally have mixed poly fibers (yellow poly rope cut every 5/8-3/4") and mixed in into non-shrinking filler cement (like Fix-It-All or equivalent).

Any one ever tried to fiber reinforce cement and then shoot it??

GOW/George

Artilleryman · « **Reply #7 on:** June 13, 2012, 01:24:11 AM »

You might want to consider Hydro-Stone. It was being used to make six pounder balls that were being fired in demonstrations at Greenfield Village. It seemed to hold up well, was accurate at 50 yards, and blew up water filled containers nicely. It is a type of plaster. Google it for more information.

Cannoneer · « **Reply #8 on:** June 13, 2012, 06:58:26 AM »

Quote from: shred on June 12, 2012, 04:08:48 PM

Bondo is pretty strong stuff when mixed and cured properly. We'd mix in a bunch of sand and make fake-rock climbing holds that held up to tremendous use and people dangling from them all day long (actually we ditched the Bondo and went to poly resin and filler-- much cheaper and works as well)

The downside is it doesn't pour rapidly. It will fill every crevice perfectly if allowed to flow and set.

I've used bondo more than a few times in the past (though not as a projo), and I agree with shred that it's tough stuff (it's like a 2 part epoxy); but even if there is something that could be added to make it less viscous, I think that a reduction in its strength would inevitably occur. Wouldn't bondo also be too light in weight to make an accurate projectile?

KABAR2 · « **Reply #9 on:** June 13, 2012, 09:39:25 AM »

The problem with light projos is they tend to go further than expected......... I have lost several pool balls that way...... make sure you have plenty of room out there on the range......

Capt Rick Hiott · « **Reply #10 on:** June 13, 2012, 11:53:34 AM »

I have worked with bondo for many years in the body shops .
You can mix regular fiberglass resin in it before you add the hardener to change the viscosity.........

Artilleryman · « **Reply #11 on:** June 13, 2012, 01:42:50 PM »

You can pour Hydro-Stone it sets up very hard. I recommend that you use something to vibrate the mold to remove air bubbles.

bartomark · « **Reply #12 on:** June 13, 2012, 11:52:56 PM »

I made a mold to cast 4.5'' concrete balls to shoot out of my coehorn mortar. They weigh about 3.5 lbs and have not had any problems with them holding together. I have tried concrete mix as well as straight mortar mix and both held up well.Mortar mix will give a smoother finish . I have used charges up to 500 gr. bp. Usually in the back yard i use 200 gr. and they go approx 125yds.I also make smaller ones to shoot out of a soda can mortar.The trick to using any cement product is to let it fully cure before shooting it. Usually 3-4 weeks. Also do not let them dry out too soon, I keep mine in sealed plastic bags for at least 2 weeks tokeep them from drying out before the cement has a chance to cure.Cheap ammo. This is a link to see them in action.I shoot with my dog,he loves to chase them. http://www.youtube.com/watch?v=5-2RiYPdE4E&feature=youtube_gdata_player

cwlongshot · « **Reply #13 on:** June 14, 2012, 02:36:46 AM »

Quote from: bartomark on June 13, 2012, 11:52:56 PM

I made a mold to cast 4.5'' concrete balls to shoot out of my coehorn mortar. They weigh about 3.5 lbs and have not had any problems with them holding together. I have tried concrete mix as well as straight mortar mix and both held up well.Mortar mix will give a smoother finish . I have used charges up to 500 gr. bp. Usually in the back yard i use 200 gr. and they go approx 125yds.I also make smaller ones to shoot out of a soda can mortar.The trick to using any cement product is to let it fully cure before shooting it. Usually 3-4 weeks. Also do not let them dry out too soon, I keep mine in sealed plastic bags for at least 2 weeks tokeep them from drying out before the cement has a chance to cure.Cheap ammo. This is a link to see them in action.I shoot with my dog,he loves to chase them. http://www.youtube.com/watch?v=5-2RiYPdE4E&feature=youtube_gdata_player

TOO FUNNY!!!

LOL thanks for the show!

CW

Blaster · « **Reply #14 on:** June 14, 2012, 03:46:49 AM »

Guess I'll have to try concrete or mortar mix. Thanks to all for the suggestions.
Also enjoyed the movie clip and happy to see that hound dog get the cannonball dug out.

Cannoneer · « **Reply #15 on:** June 14, 2012, 04:40:37 AM »

Bartomark,
Thanks for posting the vid, that's a fine mortar you've got there. The mortar looks familiar, was it made by one of our sponsors?

Double D · « **Reply #16 on:** June 14, 2012, 04:53:02 AM »

Bring that dog up here to Montana, we can use him... oh yeah bring your cannon also.

bartomark · « **Reply #17 on:** June 14, 2012, 10:21:51 AM »

The mortar was made by Dom Carpenter.Thanks for the comments about my dog Brutis ,he really does enjoy the noise and the smoke. When i get time i will post some other vids that i have shooting with him in a seperate post...........mark

A.Roads · « **Reply #18 on:** June 14, 2012, 09:08:28 PM »

May I suggest that for cheap balls you try plaster of paris (any "add water" plaster product seems to work). I use these in my slightly scaled down coehorn mortar, about 3 inch calibre. Unless they land on a rock they are reuseable - perhaps not so efficient in a cannon, unlikely to fly true - it depends upon what you are wanting performance wise.
It is also possible to cast in place a small bursting charge with a fuze sticking out the sprue hole, depending on how you do this they would not usually be reuseable - cut fuze to different length for air burst or ground burst - I'll leave that to your imagination - please note this this may not be permissable in some places.
Adrian

bartomark · « **Reply #19 on:** June 15, 2012, 10:56:22 AM »

I am going to try to cast some balls out of refractory cement. This has no limestone in it but uses aluminum as a binder. It has to be cured at increasing increments starting at 200F up to 1000f +. I am going to try to use a fresnel lens to do this. they are supposed to be just about indestructible when cured properly. i will let you know how they turn out. It may take a few weeks . Maybe this is an overkill as i have not had a failure with regular mortar mix , but these are supposed to be more dense and weigh almost twice what regular cement balls do.............

Zulu · « **Reply #20 on:** June 15, 2012, 11:02:16 AM »

Quote from: bartomark on June 15, 2012, 10:56:22 AM

I am going to try to cast some balls out of refractory cement. This has no limestone in it but uses aluminum as a binder. It has to be cured at increasing increments starting at 200F up to 1000f +. I am going to try to use a fresnel lens to do this. they are supposed to be just about indestructible when cured properly. i will let you know how they turn out. It may take a few weeks . Maybe this is an overkill as i have not had a failure with regular mortar mix , but these are supposed to be more dense and weigh almost twice what regular cement balls do.............

bartomark,
What size are you casting? What are you shooting them out of?
Show us some pictures.
Zulu

bartomark · « **Reply #21 on:** June 15, 2012, 01:14:31 PM »

I am going to cast 4.5''balls with refractory cement to shoot out of my coehorn mortar shown in a previous post with my dog.I am mostly curious to see what they weigh fully cured, someone who works with refractory cement told me it weighs double what regular mortar does.We shall see if that is accurate.as stated earlier i have never experienced a failure with regular mortar balls if they are allowed to cure properly.I plan to shoot a video showing how i made the mold and how i cast the balls as soon as i have time . i made the mold with a candlepin ball and bondo and use vaseline as a release agent............mark

bartomark · « **Reply #22 on:** June 17, 2012, 11:32:40 AM »

Quote from: bartomark on June 15, 2012, 01:14:31 PM

I am going to cast 4.5''balls with refractory cement to shoot out of my coehorn mortar shown in a previous post with my dog.I am mostly curious to see what they weigh fully cured, someone who works with refractory cement told me it weighs double what regular mortar does.We shall see if that is accurate.as stated earlier i have never experienced a failure with regular mortar balls if they are allowed to cure properly.I plan to shoot a video showing how i made the mold and how i cast the balls as soon as i have time . i made the mold with a candlepin ball and bondo and use vaseline as a release agent............mark

Well I casted some balls out of refraftory cement and they weigh the same [3.5lbs]as the balls i casted out of mortar mix.They do appear to be much stronger and harder than the regular mortar balls.when I get time I will shoot a video how i made the mold and how i cast the balls...........mark