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How to make a barebow weight with a potato

14909 Views 25 Replies 21 Participants Last post by  ArtV
Now, I know even the non barebow archers amongst us clicked on this thread just to see what I did. :shade:
Ever wanted to mold something, but didn't have any plaster of paris, or the time or inclination to make a model, mold it in the plaster, then wait a while for the mold to dry out?
In short, I made a single use mold out of a potato, then poured molten lead into the cavity and made a weight. Did this with a good friend and teammate, (Funditor here on AT), who shoots FITA barebow in addition to olympic.

First, take a large potato. Slice off a section, and hollow out the shape of the final product (We made a U shaped kinda thing that fits the bow quite close).
Proceed slowly! Don't make a sprue (pour) hole yet. When everything is as you want it, look at see- did you screw up anywhere and make the sides too thin? Hopefully, if you did, it is in a location where everything will flow freely if you make the sprue hole there. (whew!)
Good. Now put all the parts back! Notice, I made mine closed on all sides, but you could also leave one side fully open and forget about pouring into a sprue. I used nails, but you could wire it shut or something like that. I'd avoid the Handyman's Secret Weapon (duct tape), as that has the potential to melt if hot lead gets on it.

Unfortunately, we decided to photograph the effort after the mold had been assembled, so here it is after the finished product was removed. You could probably make 2 or three weights this way, but then the mold would start to degrade (errrr....overcook....) and quality would go down.

And here it is, nailed together.


Now, assemble the following-
-Propane (or other similar) torch, and something to light it with.
-A big hunk of lead (I used a 2 pound SCUBA belt weight), or many small hunks of lead (fishing sinkers or the like).
-Something to hold the lead with while you torch it (pliars)
-Something to hold the something to hold the lead with while you torch it (hot pad)
-Someone to hold the something to hold the something to hold the lead with while you torch it (your co-conspirator)
-A crucible of some sort. (True story- my co-conspirator was forced to eat tuna fish salad as we were assembling the materials). Crimp a corner to make pouring easier in the future.
-Water. Lots of water.
-Long sleeves and gloves (in retrospect, we should have done this)
-Cardboard or a similar work surface to pour onto.
-A sense of daring and adventure


Torch that thing! Make sure to drip some lead down so that it coats the bottom of the can (err... crucible), which will allow for much better heat conduction in a minute.


Once there is a layer of molten lead on the bottom of the can (to transfer up the heat from the steel crucible), you can place the rest of the lead inside the crucible, and heat from the bottom. Trust me, this step is necessary (well, unless you like burning excess fuel...), unless perhaps you used small shot (shotgun pellets) or the like, that already has a high surface area to conduct heat from the bottom.
Try to explain what you're doing to the neighbors when they come outside and start their little hibachi grill next to you. Assure them that yes, you know what you're doing.
While holding the apparatus with one hand, remove your phone from your back pocket and answer it. Wonder why your mother isn't surprised when you tell her that you're playing with molten lead, a torch, and a potato.


I'm melllllttttiiiiinnnnnggggggggg! Do this outside, away from stuff that can burn. Keep water on hand (we had it, just didn't take pictures of it.) Take a stick and scoop off all that nasty slag on top- it detracts from a high quality pour.


Remember that piece of cardboard up in that top picture that you're supposed to pour on? Yeah, to get out of the wind we moved down onto the steps into the lee of the wind, and didn't move the cardboard with us. Whoops. Removing the big chunks of lead from the sidewalk wasn't the problem (they come right up), the issue is picking up all the little tiny splatters the size of a pinhead.
Anyways! Pour that good hot molten lead into your potato mold! Watch out for splatters and steam- this is after all pouring molten metal into a moist environment. This is why I'm now recommending long sleeves and gloves.


Pour some water over it after a couple minutes, just to make sure it's cool. Lead inside the potato actually cools pretty quick, due to the high heat capacity and high heat of vaporization of water. Lead not touching anything wet (like, on the sidewalk...) takes *significantly* longer, so give it all a thorough dousing with water.
Then, open it up and pull out your product in the rough! I think initially my lead may have been too hot, giving the poor finish quality directly beneath the sprue.


Cut off the sprue, file it down a touch, make it pretty. But not too pretty, or people won't believe you made it with a potato!


Drill out a hole to bolt it on to your riser. AHHHHHHHHHH MY HAND! (Editor's note: staged photo- no hands were harmed in the making of this photo essay)


Semi-finished product- Good enough to go to practice with and try out, considering by now we were two hours late.


Bolt it on! It fits well, nice and close (especially considering I free cut the mold!), and he shot quite well with it tonight. He'll clean it up later with a finer file, and perhaps some paint.
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· Registered
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Me Three! (About the potato being bolted to the riser) That's a really smart idea.
 

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You can do amazing things with plastidip. I used to dilute it with laquer thinner to use in applications where it was too thick. It went on like paint but stayed on like rubber. But now they sell it in a spray can version as well as the original thicker dip cans. Good stuff.
 

· Wanderer
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haha I admit I am not a barebow archer who clicked on the link. I thought like everyone else you were some how mounting a potato to a bow.

Originally I thought you were going to grow a huge enough potato to be heavy enough to be worth some weight.
 

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Ingenious

I've just been looking at weights, so might give this a try! They are re-roofing the building I live in so there is about a ton (litterally) of lead in the garage outside. I could make use of their offcuts.

If you can't find a potato big enough I guess you could use a swede or turnip!
 

· Genesis 21:20
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Now that's real shade-tree if I ever saw it ;) Nice work!

Reminds me a lot of the old Hoyt Radian that I had. Filled all the holes in the lower part of the riser with lead, then used body filler to flush them up, and painted the whole thing. You couldn't even tell it was there. Made for a REAL nice shooting bow.

John.
 

· Civil but Disobedient
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Sax_man_al,

Spigarelli now makes barebow weights in 350g, 250g and 190g sizes. I own four of them. Alternative carries them (see Recurve Accessories). They are a special order item. You can also get them from Arco Sport Spigarelli, Arco e Frecce and Lancaster. Of course, they are not as cool as using a potato weight but at least you won't get lead poisoning from them.
 

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A couple cautionary notes:

Lead vaporizes pretty easily when the temperature rises too high, this is why bullet casters use an electric furnace with controlled temperature. Breathing lead vapor is really really bad its a sure way to wind up with some degree of lead poisoning.

Molten lead really hates water, a drop or two falling into the melt pot can cause a violent explosion of molten metal, had your potato been wetter the results of pouring could have been very unpleasant.
 

· Genesis 21:20
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Ahh, this is why I miss shooting barebow... Barebow archers ain't quite right, and they never take themselves too seriously (well, except for that one chap a few years ago, but it finally did him in...) which is why you always see barebow shooters having so darn much fun. It's kinda neat at most tournaments because every other archer there is jealous of how relaxed and happy the barebow shooters are, meanwhile everyone else is stressing out. ha, ha. :D Good stuff...

John
 

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Discussion Starter · #20 ·
Annnnnddddd I'm back. A friend told me I'd been attacked by a thread necromancer, so I figured I should come by and say Hi! I've been straying from archery to more high velocity lead slinging. Some of the personalities down here in SoCal take themselves too seriously... John, I hear ya.
I've been really improving my manufacturing capabilities too :wink: . Instead of casting stuff with potatoes, I broke down and bought my own desktop mill for home; just last week I finished machining an AR pattern lower (semi-auto M16).

Just spend more quality time practicing and You can cure Tartget Panic !!!!! If you need weights there is a machine shop in your that could use the buisness
That's probably why many of the top barebow shooters use weights on their bow; they just don't want to practice enough. :rolleyes:

And I'm writing this reply from my office- in a machine shop. Expect more fun stuff in the future. :wink: (of course, I wasn't in the field then, but why pay someone else when you can make it yourself?)

A couple cautionary notes:

Lead vaporizes pretty easily when the temperature rises too high, this is why bullet casters use an electric furnace with controlled temperature. Breathing lead vapor is really really bad its a sure way to wind up with some degree of lead poisoning.

Molten lead really hates water, a drop or two falling into the melt pot can cause a violent explosion of molten metal, had your potato been wetter the results of pouring could have been very unpleasant.
Outside, upwind.
Just like lab- Remember "Always Add Acid"? Similar concept.
The idea of using a potato for molding lead wasn't mine, I picked it out of a book on how to make your own fishing equipment. Although looking back, safety glasses or a face shield should have been required equipment. Burns and scars are cool. Eye injuries aren't...
So, a potato is probably not the /safest/ method, but sitting on your couch and paying someone else to do it is even safer than making a real mold. Field expediency =P. After all, I play with sharp sticks (You'll poke someone's eye out!) and blades and guns and deal with Californians.

When lead is molten, it releases minute amounts of vapors at a progressive rate as temperatures are increased. Harmful levels of lead vaporization are believed to occur at elevated temperatures above 1800 degrees (F). Only lower temperatures between 700-800 degrees are normally needed to cast lead hobby parts.
From http://www.kansasangler.com/makeit.html

1800*F will turn steel (like the tuna tin) well past a full cherry red (of about 1500*F), says http://www.muggyweld.com/color.html. I'm pretty sure it didn't get anywhere near 1800*
Other reasons to keep your lead on the cool side (aside from offgassing) would be energy use and to keep a consistent amount of shrinkage in the product. Hotter lead heats up the mold more, so you need more time to cool between pours. Remember, the difference between .451" and .452" is important for firearms, as is the grain weight of the ballistic. Yes, you use a sizing die to bring it down to final diameter, I know. But garbage-in-garbage-out...

-James
 
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