53 replies to this topic

[shmmee]

Presenting: Gumdrop dart heads!


A homemade, consistent, metal free, mass producible dart head made from materials readily available at almost any hardware and craft store!
It uses a home made mix called "oogoo" as the main dart head material (silicone caulk + corn starch to shorten cure time). http://www.instructa...gru-Substitute/ Read it, it's great.

With recent advances made, I feel confident enough to present this as a completed and functional product. The bond of the head to the felt backing is nigh inseparable! I pulled with my fingers, and gave up. I pulled with pliers, and the head tore in half before separating from the felt!

Credits: Thanks to Darth Maker for the discovery of oogoo, Taerkitty for thinking up the felt backing, and Just some Bob for coming up with the gumdrop name. Also thanks to those who helped with other ideas, and encouragements while this concept was being developed. This has truly been a group effort, without the nerfing community (special thanks to Nerfrevolution.com, where this was developed), it would never of gotten off the ground.

The format of this write up will be a written format, supported with video of the process. That way everyone can see just how incredibly easy these things are to make.

Materials:
For pointy heads - a polyethylene (white plastic) cutting board of any thickness greater than 1/4".
For flat heads - 3/8 - 1/4" white plastic cutting board (2)

counter sink: "four cutter cutting bit" ((It's a counter sink with an adsustable center bit - sold at any hardware store)#10, or #12- though #12 heads have been known to jam a hopper - but that could of been a pre-felt separation issue. I'll have to re-visit #12's the increased surface area might help decrease pain.)

3M window and door silicone caulk (or any other clear silicone caulk with a ton of warning labels on the back. NOT GE II silicone. It cures by releasing moisture instead of absorbing it.) It should reek of vinegar while curing.
corn starch
Ziploc bags (to mix in) Gallon size for batches larger than 100 heads
square of felt large enough to cover your dart form.
Mineral spirits (optional - softens the final product)

Tools:
A work space you can temporarily stink up.
Drill press or drill with masking tape to mark a depth/ stop drilling ring
Wood paint stir sticks
scrap sacrificial board - opt. (to make a flat head form put it under your cutting board as you drill, any flat drillable material will work)
clamps/screws - opt. (helpful)
scissors
caulk gun
3/4" (or larger) scrap of PVC to use as a roller, longer scrap of cpvc to slide in and use as an axle.
Packing tape (or other) to tape your mixing bag to the table to hold it in place while you mix.
#10 (.375") or #12 (.425") "four cutter counter sink (For pointy head darts)(or a normal 3/8" or 7/16" drill bit - for less pointy heads) to drill your form with.
Uni-bit to pilot drill your form holes (for flat holes) (optional) They stay centered better, so you can space your holes closer together.

Materials Video: (click to open in new window and view. Not sure how to embed video. Feel free to PM me with pointers. Also, wow I hope I really don't sound like that. I sound like frekin' Kermit the frog.)


Form making basics

The majority of time spent on this project will be invested in making your form, but it's infinitely re-usable, so no big loss! Spend the necessary time to lay it out well, and do it up right.
Space your holes as close as you dare to drill if you plan on separating the heads with scissors, about 1/8" apart if you plan to separate them using a punch. Use the width of your counter sink as a guide. I laid the flat tip of mine on the edge of my board and traced around it with a permanent marker, then drew lines coming off of the point with a framing square. Try to line your holes up in straight lines so you have the option to cut them apart with scissors if needed. Off centering every other line will fit more dart heads on the mold, but it will add time to cutting them out. Leave at least a 1/2" border unrolled around the outside of your form.

To make a pointy head form: (Easiest, but not by much)

Set the depth of the internal shiny drill bit in the counter sink so it's barely poking above the black part of the bit (adjustable via hex screw). Chuck it up in your drill press / drill. Set your depth to 1/4" below the surface of the cutting board. (Less if you want shorter heads, more if you want taller heads). Drill out your heads. This plastic drills very easily and cleanly, but it did leave some scraps clinging around the center hole, so go back through and check to make sure their aren't any small pieces left behind.

To make a semi-flat head form:

Use some fine bolts (or even spare nerf gun screws) to join your cutting board to your sacrificial board. The sacrificial board will keep the edges on your exit holes clean and level.
Adjust the depth of the drill bit to to drill partially through your cutting board and into your sacrificial board. The size of the exit hole in the cutting board will be the diameter of the flat spot on your head. Your heads will be as tall as your cutting board is thick, so be picky when you buy your board.
Use a "four cutting" counter sink to drill your holes partially through your cutting board, and into your sacrificial board.

Credit for the backer board goes to Taerkitty and originally K9 for suggesting drilling through and using a backer board to take off the point.

To make a flat head board (cylinder):

Drill through your cutting board (1/4" to 3/8" thick board - board thickness defines head height) using a 3/8", or 7/16" bit (depending on how tight you want your tolerances, and how heavy you want them to be). Bolt another cutting board behind it.

To tip the cylinder heads in felt - prep felt discs by using a hollow punch and a hammer to pound through stacked layers of felt (I've gone through 6 at a time) separate the discs, and place one in the bottom of each hole. Gently separate the board from the backer (nothing holding the discs in place but friction), coat the back of the form in backing tape, re join the form and backer, then press the discs into the tape to hold them in place. (You'll have packing tape sandwiched between your form board, and backing board.)

(Currently developing similar method to tip them in dryer lint. - hopper feeding with out felt discs on the tips)

Mixing oogoo

Squeeze silicone caulk into a Ziploc bag (use a name brand bag with the double strips of seals. It's a wasteful mess if the bag opens while mixing.) 6 complete squeezes from the caulk gun makes 175 3/8" tall heads. If you want to add mineral spirits, to soften the final product, or oil based paints to change the color, add it and mix it in now. I don't have an exact ratio of mineral spirits figured out here. I just added and mixed till it didn't feel quite so thick. Tape your baggie down to a table, and mix it back and forth with the roller.

We haven't added the corn starch yet, so no rush. Make sure you have every thing you need for the rest of the process close at hand, and your form is secured some how to the table. If you're making flat head darts, screw or bolt your drilled head form onto an undrilled piece of cutting board. (That will keep oogoo from shooting out the back) Once you add the corn starch, the clock starts ticking!

Add 1/2 spoon full of corn starch for every 1 squeeze of silicone into your bag. Squeeze out the air, and tape your bag down to your table, make sure it is sealed, and mix it together with a roller. The corn starch shortens the cure time of the silicone from 24-48 hours down to 2-4 hours!

I thought I took video of the mixing, but it didn't take. It's pretty self explanatory, I'm sure you can figure out how to mix two or 3 ingredients in a plastic bag.

Filling the head form

Video (again, click to open in new window and view):


Written instructions:
Once mixed, roll every thing away from a corner, and lop off a large corner from the bag. Roll it back towards the corner, and squeeze the glob out onto the form.


Glob of Oogoo waiting to be pressed into the head forms. You can see the backer board clamped to the head form board in this pic it was just a small, trial sized board though. I would recommend bolting them together. (It should reek of vinegar. Open windows and such.)


Smear it into the divots with a paint stir stick, scrape off the excess.


Lay your felt over the board, and go over the top of it with a roller. Rub your thumb swiftly over the top of the felt. This will help work the uncured mixture into the fibers of the felt.
Allow to cure (should feel semi firm if poked). I have waited as little as 4 hours to remove them from the mold.
[I'll add a video of the dart heads coming out of the mold as soon as I can take it.]
Once cured Pull the felt off of the mold, and the heads will come with it! Separate the heads by either cutting them apart with a pair of scissors, or use a punch and hammer (harbor freight - $8)

Pointy (before we discovered felt backing):

And after we discovered felt backing:

Flat (before we discovered felt backing):

Cylindrical felt tipped heads:
[pic goes here once they're out of the mold]

Note: save your unused tube of caulk for later by cutting a corner off of a plastic bag, fill it with silicone, and hold it on with a rubber band.


Now glue the felt side to your fbr using your favorite glue and be done with them! [I'll update with a pic of some finished darts later]

Ranges: depend largely on the size of the dart produced. Previous (heavier versions) flat heads have out ranged my slugs by 25'. It's raining all week here in Utah, can't do range tests.

Pain: Hurts about as much as getting shot with a hot glue dome. Comparative pain tests say less than getting shot with a hot glue dome.

Hopper feeding: sucks.

We may want to work out some sort of padding/coating on the tip. The oogoo site says fresh oogoo will stick well to cured oogoo. We may want to make completely flat heads by drilling straight through, and use oogoo to glue on felt pads post curing. I can't think of a way do do it during the initial form up. If we sandwiched the form top and bottom with sheets of felt, we would be unable to remove the heads. Maybe dropping discs into the heads pre fill? See above edit entry: Flat heads (cylindrical)
- feel free to throw out some suggestions!


(see slugs domes and other dart heads thread for development http://www.nerfrevol...t=2443&start=60, as well as the original counter sink dart heads thread: http://www.nerfrevol...&p=30679#p30679

[edit: added form description - cylindrical heads]

Edited by shmmee, 31 May 2011 - 10:58 PM.

[SonReeceSonJensen]

Mother F RIGHT! Nice work Mr. Schmii.

Now, on to the questions: Do these heads cause friction or ‘sticking’ in a hopper clip or a wye like the head of a streamline will? Or will they slide smooth like the felt head of a slug dart?

[shmmee]

Mother F RIGHT! Nice work Mr. Schmii.

Now, on to the questions: Do these heads cause friction or ‘sticking’ in a hopper clip or a Wye like the head of a streamline will? Or will they slide smooth like the felt head of a slug dart?

Previous versions (without the felt binding) had serious adhesion issues, and have come off while rounding the bend - jamming up mid barrel. These with the felt backing are much stronger! I'll hopper test them tonight. My hopper is a homemade one - a coupler welded to the back of a 45, and a pair of air holes through the 45. I left a center post in the middle of the wye to help guide darts around the bend (like a britt hopper), so it may not be an accurate performance baseline of a standard Wye. They don't have the stems that impair streamlines, so I expect they'll work well.

Edited by shmmee, 18 May 2011 - 01:04 PM.

[Draconis]

I've done this before, but I have to say... The felt backing is a stroke of genius. I still don't see them working well in hoppers ever, but for anything else, they should be great. One thing I really liked about the batch I made was the rebound. I could stand fifty feet from a concrete wall and fire one of these with a 2K... and it would nearly make it back to me on the rebound.

EDIT: Missed this before...

Pain: Hurts about as much as getting shot with a hot glue dome. We may want to work out some sort of padding on the tip.

You are using too much cornstarch, if that is the case. Mine were substantially heavier than yours, fired from a plugged 2K at pointblank range, and were definitely not as painful as hotglue domes. Use less cornstarch and they will be softer. The cure time may increase a little, but to be honest, why wouldn't you just leave them over night?

Edited by Draconis, 18 May 2011 - 02:35 PM.

[VACC]

It seems like they are a lot more time consuming to make, and you say the impact force is similar to that of a hot glue dome. I guess my question is, what is the major benefit of these dart heads over other contemporary dart smithing methods? I'm not being sarcastic or snide here. People seem genuinely excited about this, and I'm just wondering what this new method offers in terms of improvements.

[shmmee]

It seems like they are a lot more time consuming to make, and you say the impact force is similar to that of a hot glue dome. I guess my question is, what is the major benefit of these dart heads over other contemporary dart smithing methods? I'm not being sarcastic or snide here. People seem genuinely excited about this, and I'm just wondering what this new method offers in terms of improvements.

That's a fair enough question. I really would be shocked if any new unproven technology is greeted arms wide open without scrutiny.

Pros:
-No Mcmaster order (or shipping costs). All materials are waiting for purchase at your local hardware store, and craft store (felt)
-No metal weight of any kind. when a slug head separates mid flight, you have a projectile that's half felt pad, half metal washer with the potential to cut someone.
-Consistency - as long as your form is consistent, and your fill is complete, each head is identical in size, shape, and weight.
-Durability - Felt is a more porous bonding surface than metal, and is more likely to withstand abuse.
-Range - I've seen a 25' increase in previous batches compared to slugs. (I do realize there slugs are often required because of their limited range to improve game play)
- Accuracy - this has yet to be verified, but it seems logical that a heavier dart head would fly in a straighter line.
-Repeatability - Even a new dart maker with a form can produce consistent results equal to a seasoned dart smith.(which increases the overall safety and quality of darts on the field.)
-Customization- Add oil based dyes during mixture, couple with the dozens of different colors of felt, and make darts that are recognizably your own.

Cons: (yes, for the benefit and perpetuation of this discussion I'm also listing problems that I've seen. That way we might get more suggestions in, and either accept the limitations, or fix them.)
-A form is required Sure, you can make one yourself, but that's time that could be spent doing something else.
-More time and effort compared to slugs. 'Nuff said there.
-Currently lacking padding on the tips.
-Their isn't a glue on the planet that bonds extremely well with the silicone. (Trust me, I've tried close to a dozen!)Adding the felt backing was a last ditch effort to give us some way to glue finished heads onto dart blanks. Any glue bonds to felt! (The oogoo instructables website claims that fresh oogoo will bond to cured oogoo. Since oogoo bonds to felt and porous fabrics, we may be able to use oogoo to glue felt padded discs on after they've cured.
- Hurts like a hot glue dome. This needs further development, but isn't integral to the basic performance of the darts.
Increased range - this is included in both lists, because not everyone will view bigger ranges as a good thing.
- Poor hopper performance - Roughly 1 shot of 6 failed to fire on the first shot. That's a big issue. We'll need to pad the tips some how, even if only to reduce friction.

Sorry Just some Bob, Had my wife shoot me from 10' away with my pas (with added ls spring, 12" straight barrel, no hopper.) and one of the lighter pointy tipped darts. I definitely knew when I got hit. Though that was close range and a high powered blaster. I'm sure a slug would of also hurt under those circumstances. At the very least it was nothing like getting hit with a stock dart shot from a near stock blaster. The outcome might be different with a lower powered blaster, or normal ranges.

Anyone who shoots someone else from that close with any homemade dart and mid/high powered blster is going to leave the victim with a welt, and probably be labeled a douch. I just have high standards for these things, and think the pain factor can be reduced by the addition of padding. The increased surface area of the flat head darts may also help substantially. I just haven't made any of those in the felt backed edition.

Edited by shmmee, 19 May 2011 - 08:18 AM.

[taerKitty]

Some places either are forbidden to shoot anything metal, no matter how sealed/encased/entombed, or self-regulate and refuse to shoot metal-containing darts for fear of having Nerf itself be banned. I'm not sure which it is, but Sg and Oz Nerf sites both seem free of BBs, ball bearings, washers, etc. in their darts. Also, as Bob said, 'office wars' will likely object to any bit of metal flying, no matter how it is packaged. I know I don't shoot at my coworkers, or into offices with anything besides stock ammo.

I have some of inf0rm3r's cast-silicone tips and tubular foam in transit, but I recall someone else reporting that they sting like a glue dome as well.

I suspect pain is a factor of surface area, so having a larger striking surface (i.e. slugs) will lower pain more than a spongier material. Perhaps we can just make a cylindrical 'head' that has no tapering at all, and see if that helps with the pain.

===

Edit: inf0rm3r's silicone tips just arrived. They're much harder than oogoo. They have more give than hot glue, which doesn't say a whole lot, but they do flex a little. They're also quite heavy (1.8g if memory serves).

Edited by taerKitty, 18 May 2011 - 05:07 PM.

[Ozymandias]

I'm not sure which it is, but Sg and Oz Nerf sites both seem free of BBs, ball bearings, washers, etc. in their darts.

I suspect pain is a factor of surface area, so having a larger striking surface (i.e. slugs) will lower pain more than a spongier material. Perhaps we can just make a cylindrical 'head' that has no tapering at all, and see if that helps with the pain.

Custom Calibrated Foam Darts - Conversion Guide!
Custom Weighted Foam Darts - Tip Seal Guide!
Example of them being used: SGN R-Series Blaster - PAR55M Demo

Airsoft and similar toys are banned in Singapore and Australia. The less airsoft-y they can make darts, the better. Thus, no metal.

Moving the eraser bit back would provide more padding on the front; however, that would move the center of gravity back which would make the dart less accurate (I think).

Edited by Ozymandias, 18 May 2011 - 07:43 PM.

[Langley]

-Repeatability - Even a new dart maker with a form can produce consistent results equal to a seasoned dart smith.(which increases the overall safety and quality of darts on the field.)

You would think that, but then you would also think that anyone could manage to put a felt pad and a washer on a dart without fucking it up. Until other people start making these, you have no way of knowing whether others will find a way to mess up one of the many additional steps that this process adds to dart making, including variation in the depths of the countersunk holes, extra pointy dart tips, and of course the potential for tip separation.

I'll grant you that these are probably much more consistent than domed stefans when you make them with your mold. They may be safer than shoddy, incorrectly made slugs as well. I have to admit the idea of mass producing a standard plastic nub for your darts sounds pretty cool. But I can't say for certain whether I would allow them at what would otherwise be a slugs-only event.

[taerKitty]

Slugs is slugs. If the war organizer says, "No" but allows double-slingshot stefans, that's his call. (I may chose not to risk my safety in that war, but that's me.) If, as some have said, the goal of requiring slugs is to 'even out' all the blasters, these certainly shouldn't be used. Just state that as the goal, and don't pussy-foot around by making handwaving FUD about 'safety' or 'untried' or whatnot. You want to equalize ranges, say it up front and I'm all for it. Otherwise, I may be egalitarian in many ways, but I do believe in a meritocracy, within reason: if you can make a blaster push a dart safely to 120' or 130', or even 150', go for it.

Just be prepared to take a shot at 10' with your god-cannon. If you won't allow anyone to tag you at that range, I would object to you pointing it at anyone else.

===

I think the question of molds can be addressed by selling them. I'm a strong believer in teaching a man to fish, but that still requires he somehow acquire the rod, tackle and bait. Here, I can easily see someone with high craftsmanship making molds and selling them so those of us lacking a drill press (or a drill, or just the steadiness of hand to free-drill 100+ holes to such exact depth and angle). It still means more people can be dartmakers, and we not rely just on dartsmiths.

===

As I see it, in the event of a catastrophic failure, we don't have a disc of metal with some fuzz stuck to it flying through the air. We do have a blob of airborne rubber, which may pack just as much force, but it both has some squishiness and lacks the chance of hitting on the edge or along the cut corner. As I've said on IRC, I've seen overpowered blasters manage to somehow launch the head and foam of a slug as two separate simultaneous projectiles. The foam blank goes a few feet, but the head can exceed the distance the blaster normally can push a slug. Specifically, I've seen solo heads go flying over 150' out of an un-up-powered 4B (i.e. stock OPRV, no tank expansion).

===

I figure all experiments are worth considering. Those that are not safety hazards or otherwise can be rejected out of hand because of trouble, expense or NIC-acceptance, should be tried, first in small batches, then shared with the rest of the NIC for general evaluation. I did the same with my nuthead darts, and have since stopped development on them because I couldn't center them well enough.

I don't foresee anyone mandating them for future wars. I don't see 'slug-only' wars being forced to allow them either. I hope to see more and more people making their own ammo and less "WTB: Stefans" posts. I like seeing us all become individually independent so we can all grow our skills free of reliance on each other for key components. By having many members going their own way, I hope they can make many individual discoveries and contribute back to the NIC

[shmmee]

You are using too much cornstarch, if that is the case. Mine were substantially heavier than yours, fired from a plugged 2K at pointblank range, and were definitely not as painful as hotglue domes. Use less cornstarch and they will be softer. The cure time may increase a little, but to be honest, why wouldn't you just leave them over night?

Very nice! Do you know what ratio of corn starch to silicone you were using? Adding mineral spirits does soften them substantially, but reduces the inseparable bond to a mere great bond. They still took quite a bit of pulling to separate the head from the felt, but they were able to separate none the less. The bond is still far stronger than gluing oogoo directly to fbr, so it should still be adequate for a war, but it could be easier to skip the mineral spirits and reduce the corn starch. Reducing the amount of corn starch might decrease firmness without compromising bond strength.

I did some hopper testing yesterday. Roughly 1 shot out of 6 failed to fire on the first shot. I would definitely count that as unacceptable. For them to work reliably with hoppers we'll need to investigate a way to add felt to the tip to reduce friction. I'll add that to my pro/con list. I received a 1/4" thick cutting board yesterday. I'm going to just drill straight through and bolt a backer board then try some cylindrical heads. I need to get a punch set first though, so I can punch some felt discs, and drop them in the bottom of the forms.

[Draconis]

Very nice! Do you know what ratio of corn starch to silicone you were using? Adding mineral spirits does soften them substantially, but reduces the inseparable bond to a mere great bond. They still took quite a bit of pulling to separate the head from the felt, but they were able to separate none the less. The bond is still far stronger than gluing oogoo directly to fbr, so it should still be adequate for a war, but it could be easier to skip the mineral spirits and reduce the corn starch. Reducing the amount of corn starch might decrease firmness without compromising bond strength.

I did some hopper testing yesterday. Roughly 1 shot out of 6 failed to fire on the first shot. I would definitely count that as unacceptable. For them to work reliably with hoppers we'll need to investigate a way to add felt to the tip to reduce friction. I'll add that to my pro/con list. I received a 1/4" thick cutting board yesterday. I'm going to just drill straight through and bolt a backer board then try some cylindrical heads. I need to get a punch set first though, so I can punch some felt discs, and drop them in the bottom of the forms.

It was about 10:1 silicone to cornstarch. I have yet to actually test the density of caulking silicone, but all of the web resources say that most silicone rubbers have a density between 0.9 and 1.2g/cm^3. With an estimated density of 1.0g/cm^3 and an estimated tip diameter of 1.0cm, you should be using molds that are about 10~11mm deep to meet the current specifications for slugs and APOC standards. So how deep are your molds? I expect something like 1/2" or so, correct? If you drop a felt disc at the bottom and use another on top, they should be perfect. Except for, you know, being 1/2 an inch longer than your other darts.

[shmmee]

It was about 10:1 silicone to cornstarch. I have yet to actually test the density of caulking silicone, but all of the web resources say that most silicone rubbers have a density between 0.9 and 1.2g/cm^3. With an estimated density of 1.0g/cm^3 and an estimated tip diameter of 1.0cm, you should be using molds that are about 10~11mm deep to meet the current specifications for slugs and APOC standards. So how deep are your molds? I expect something like 1/2" or so, correct? If you drop a felt disc at the bottom and use another on top, they should be perfect. Except for, you know, being 1/2 an inch longer than your other darts.

Actually my most recent darts are about 3/8" deep + felt. My next generation (clylinders) will be 1/4" deep, but hopefully a little wider (a full 3/8" wide) to increase surface area. I don't think I've done any that come close to a full 1/2" deep. How have they worked for you? I don't know if you've had a chance to try the felt backing yet, but have you had any trouble keeping them glued on?

I'll try your 10:1 ratio of corn starch with a felt tip on my next batch. (As soon as I get the next form set up.)

[Draconis]

I have not made any in a while, but I was molding the silicone right on to the foam, and it worked pretty well. I was just showing you what kind of dimensions you would need to have to meet the mass standards provided by the APOC thread and most Slug darts. What I am saying is that if you don't make the heads weigh enough, you'll get poor stability and distance. But the material has it's own limitations.

[shardbearer]

Based off a 10.1 oz tube of GE II weighing 0.8417 lb, a 3/8" diameter, 1/4" deep head would be 1.544g.

Edited by shardbearer, 19 May 2011 - 01:41 PM.

[shmmee]

Based off a 10.1 oz tube of GE II weighing 0.8417 lb, a 3/8" diameter, 1/4" deep head would be 1.544g.

Just to avoid frustrations, Ge II silicone is listed on the oogoo instructables thread as one of the silicons that won't cure faster with the addition of corn starch. It's one of the caulks that cures by releasing moisture instead of absorbing it.

The weight calculation should be pretty close by volume between brands. Thanks for figuring that out.

To those well versed in steffan weights - would 1.544g be too heavy, too light, or just about right? I haven't started drilling on the next form yet, so it would probably be good to know if I should carry on as planned.

[shardbearer]

I messed up pretty bad on that calculation. 1.54g is really heavy for a dart, more than a slingshot, but it should be quite a bit less once I redo them.

Can someone check my math?

pi*.125^2*.375=0.0184 cubic inches per head

.8417/10.1=0.0833 lb/oz=20.9367 g/cubic inch

.184*20.9367=0.3852 g/head

In comparison, the heaviest airsoft bb was .43g and copper plated steel bbs are .38g.
Doesn't seem to be right for the ranges achieved.

Alternative calculations:

0.0184 cubic inches = .3015 cubic centimeters

1 g of caulk=1 cc, so weight would be .3g.

Or you could take 100 of them to your nearest post office where they have really accurate scales.

Edited by shardbearer, 19 May 2011 - 04:12 PM.

[Draconis]

What the fuck, man... Why would you even start with Imperial measurements EVER...

You can't measure the whole tube and expect to have an accurate measurement of the silicone inside.I happened to have an old 10.1oz tube of Vulkem here, so I stripped off the tube from the dried out material inside, and it measures about 2.0oz, or 0.125lbs. So using your measurements... 0.8417 - 0.125 = 0.7217lbs = 327.35g. 10.1floz = 300ml or 300cc. 327.35g/300cc = 1.09g/cc.

3/8" wide x 1/4" deep head ~/= 1.0cm x 0.6cm = (Pi x ((1.0cm/2)^2)) x 0.6cm = Pi x 0.25sqcm x 0.6cm = Pi x 0.15cc = 0.47cc

0.47cc x 1.09g/cc = 0.51g per cylindrical dart head, not including the mass of the felts or adhesive to the foam.

[Darksircam]

I used a cheap Wal-mart cutting board that cost around $3 - about 3/8" thick, and 8x11 inches. I think it's easier to drill through than the cutting board material you used, and it's translucent.
Instead of a counter-sink bit, I used a 3/8" drill bit. Tried a countersink, but my hand drill drilled through incredibly slowly. The one issue that might come up is the oogoo squeezing between the backer board and the mold, thus making the tip slightly wider.

Trial run to get the method down - used about a 1:4 ratio of cornstarch:silicone, just barely got everything out after mixing for a good three minutes. It started forming a film and refusing to stick as well after that. Was putty-like for about two minutes, not as readily sticking to things. Recommend using a very small amount of cornstarch, 1:10 sounds about right, in order to keep it liquid in large batches.

I wonder if sticking some hotgluable substance into the molds beforehand would allow the dart heads to be glued on that way... then you can get the felt ends as the head, and eliminate the pain factor from high-powered blasters.

Hurts less than foam-tipped slugs in a SNAPistol that gets 50 feet. It also feels slightly lighter than the slugs, though both are too light to tell reliably by hand.

Edit: Wut. My felt tore, leaving a thin layer of fibers on the dart base. I stuck it back on. If I put felt on both sides and rip it off one, I can then glue it on the torn side. The intact side acts as the tip padding, as there's no leverage to make it tear.

Edited by Darksircam, 21 May 2011 - 07:38 PM.

[shmmee]

Edit: Wut. My felt tore, leaving a thin layer of fibers on the dart base. I stuck it back on. If I put felt on both sides and rip it off one, I can then glue it on the torn side. The intact side acts as the tip padding, as there's no leverage to make it tear.

That's awesome! It's great to see more people experimenting with this concept! Could you post a pic of your padded tips?

Of a curiosity, do you have any idea how thick your felt is? It seems to me that the higher ration of corn starch, the stronger the felt bond, the more resistant to tearing off, but the harder the head is. The felt I've used is propapbly the thinnest cheapest felt available. (craft store) It's just pure speculation, but because there is less material between the two bonds (head/felt bond and FBR/felt bond) they may bond to more common fibers, and result in less propensity to separate. Heads separating from the felt is new news to and I'm certainly not saying it isn't possible, but if it was filming up before you could finish getting the felt on, that might explain the failed bond.

While I still haven't been able to do any measured range testing, I did have a chance to do some serious war testing. Of all the darts I was able to find after the war, not a single one showed even beginning signs of failure. Some were glued to the fbr with hot glue, some with goop. The hot glue ones were much faster to build, but that's just because of the quick set time of hot glue.

They did hurt less than hot glue domes, and it was agreed that gumdrop heads would be an acceptable dart head material for future wars. (We eventually agreed to get away from domes, due to the ouch factor.) Hopper tests (with out any felt on the tip) was a substantial failure. It would only fire every other shot- the first shot serving to prime the dart into position. That's a problem that will need to be corrected if these are going to receive any widespread acceptance. My barrel fit/length may of been a little off as well. I forgot to shorten it due to volume loss added by the hopper.

I spent most of the wars shooting them out of my barrel replaced (just a basic insert done - for now! hee, hee, hee.) big salvo. Wow, I love that gun. My last batch could stand to be a little heavier - based on flight characteristics displayed, and as previously discussed - could use a larger surface area to absorb impact. The salvo and I (with gumdrop head darts) did well over all, getting more than our share of hits during the war. The slc nerf scene is definitely picking up!


Keep up the experimenting. I really do like to see pics of this concept, as well as successes and especially failures being documented.

[Darksircam]

Scrap the idea of ripping the entire felt sheet off - too much surface area, too hard to pull off.
However, after cutting, I can set up the molds beforehand by sticking a circle of felt inside. The felt I have is 2mm thick, so I peel the excess thickness off and stick it back in the hole. It's not that the bond failed, but the felt just fell apart. The felt was from Michael's. Super fuzzy. Don't remember the price, it was a while back. It was also cheap felt though.

I plan to test putting felt scraps or shredded fabric into the holes for the next test. If the silicone bonds with some of the fibers, it will stick. And the original felted side can be used as the tip.

Edited by Darksircam, 22 May 2011 - 02:00 AM.

[aj1234119]

Shmmee, have you tried a brithop-type configuration with cpvc to see if that will make the darts feed through hoppers? I would think that that possibly coupled with Taerkitty's SlantHopper could get these to feed reliably in a hopper. My hopper is currently set up like this and it has almost never misfeeds, even with 2'' slugs.

[taerKitty]

Actually, reading about shmmee's misfeeds was what inspired me to come up with the Slant Hopper. But, reading more would show that his darts sometime get jammed up in the barrel as well. I think there's a quick fix to that.

Shmmee and I have spoken on IRC about his barrel 'recipe'. I recommended using a shorter run of CPVC, say 4", and 'telescoping' that with PVC to his , original length of 10". He's using a springer, so it's a 'slower' energy release than an airgun. My 4Bs use about an inch of CPVC, which, after being reamed out, has the narrowest section (1/2" ID) barely a quarter inch long to hold the dart from falling out of the wye.

[shmmee]

Shmmee, have you tried a brithop-type configuration with cpvc to see if that will make the darts feed through hoppers? I would think that that possibly coupled with Taerkitty's SlantHopper could get these to feed reliably in a hopper. My hopper is currently set up like this and it has almost never mis feeds, even with 2'' slugs.

My wye is actually a homemade. I took a coupler, miter cut one end at a 45, and plastic welded it to the back of a 45 elbow. I then dremmeled out two holes for air to pass through - leaving a guide post in the center. Instead of reaming out the cpvc and pvc it's nested into - I extended the cpvc beyond the pvc, reamed it to a knife edge, then heated and flared it out till it was touching the walls of the wye. In doing so - it does sit farther in than had I simply reamed the pvc, and cpvc. Perhaps the dart is impinging upon the flared cpvc before the tail has passed the bend.

It's performed well with slugs, and pom-pom tipped darts. I recently realized that my valve at the top of the feeder tube is not air tight. That could explain why the occasional dart would stop mid barrel. However the leaky valve wouldn't explain why the first shot is needed to prime the dart, and the second shot fires it (sometimes).

At the next available opportunity, I'll ream the cpvc and pvc to a more standard set up, and replace the feeder tube valve with a simple cap and see if those changes affect performance.

[Darksircam]

Did some testing with hoppers.
Homemade hopper as well, but there's nothing that the dart may catch on. CPVC+PVC slant, glued on the outside only.

I believe it might be the friction from the silicone tip preventing it from feeding fully. It takes two shots to fire from a BritHopp - when shook, it fired in one. But with a normal hopper barrel, I either fired it in one shot or it didn't fire at all. The dart took some persuading to fit into the reamed out barrel.

Tried to test by covering the tip with some material, but the chemical/adhesive resistance of the silicone tips works against us again. Modge Podge (craft glue/sealant, basically school glue) failed - did not adhere to the silicone at all. If that worked, you could just dip the tips and problem solved.

So I made a duct tape cap to cover the silicone. It fired in one shot, same case with three trials. The duct tape cap flew off afterward though - again not sticking to the silicone. This is evidence that the tip friction is the problem.

I also shot a 1/2" slug of silicone from a PETG barrel on a SNAP. It popped out, about six feet of range.