SpudFiles

out of curiosity....if i recover some inner tube, what might be the best way to attach it to the body of the slingshot?

I think joerg normally just wraps them with string and ties it. On occasion his slingshots have clamps for bands... The tire tubes I used are so weak it's only really good to barely feel an airsoft bb... I would suggest getting a replacement slingshot band at walmart. If tire tube is your only option, I think lots of thin strips work better than one thick one too...

Here is the video about The Massive:



I use a flex disc grinder, and yes, I have done the welding myself. I am getting pretty good with the welding and grinding.

Regarding inner tube, the stuff you find these days doesn't work very good. They changed the vulcanization process, most of the flexibility is gone.

If you don't have access to good rubber, then you can use office rubber and chain-link them for power.

Attachment: I recommend using thin rubber strips for the fork attachment. Just pull the rubber out as far as possible for a tight wrap. Pouch side, use string, and the constrictor knot (instructions on youtube).

Haha, I must say that after all the sexual innuendo regarding this slingshot, I couldn't help laughing when watching the video

Very well made, functional slingshot though.

My $10 slingshot rifle.

The Aluminum clamp was $8.99 at Harbor Freight.

All the wood was from my scrap pile.

My Chiroprator donated the Theraband.

The little hinge was salvaged from junk.




A very, very simple, trigger mechanism.

Simple to lock the marble in place and very easy to pull.




I tried cocking by using the nylon rope as a stirrup from which to pull at first. Later, I discovered that if I push the mechanism down to the ground it is much easier. I could also use a ledge to step on for the last heavy push.

Cool! How does it shoot?

If you push the mechanism down - aren't you looking right at the bullet, "down the barrel" so to say?

Jörg

JoergS wrote:Cool! How does it shoot?

If you push the mechanism down - aren't you looking right at the bullet, "down the barrel" so to say?

Jörg

It shoots perfect!

I have not dialed in on the pre-stretch length.

For a rifle, I want the trigger about 13" from the shoulder stock.

It is light enough to hold the shoulder stock/handle in one hand and the trigger mechanism in the other.

The "U" channel aluminum barrel is sturdy enough to take a 100+ pound draw without bending.

I will do some 80 grain glass marble chrono shots today.

The mechanism is designed to rise up to a line 1/4" below the pouch and no further with enough clearance as to never be hit.

The surprise to me was how fast and easy it is to cock.

The draw can be made using several steps and/or techniques:

Step on or insert shoe into the rope stirrup and full draw.

I worry about an accidental bounce off a hard surface.

Manually pull to mid draw, place the stock on the ground and press down.

I like this method because any accidentally loose projectile will fly up away from my head.

Manually draw mid way, place the stock on the ground, and step down on the mechanism opposite the trigger area.


Manually draw mid way, place the stock on my shoulder, and pull to full draw using both hands with the barrel aimed at the target.

This is like you do it.


Joerg, we built our rifles like tunnel diggers who start at opposite ends and meet in the middle.

I would like to try tapered Theraband gold on a clamp fork.


It is the best $10 toy I have built so far.

Anyone have a name for it?

The Boyntonsling?

I built a new slingshot today. Y shape, machined/welded stainless steel. Polished. I need to order some bands then I'll post pictures.

How about the "Boynton-Banger"?

or simply; the Boynton-Bow?

Maybe the "Stu-Shot"...

SlingShoT-U

With that capitalisation, of course.

5 Kg draw yields 100 M/s and 27 Joules!

Can you explain this noteworthy efficiency?

I don't get it.

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Using a 48" Aluminum clamp from Harbor Freight as a base a fork and a very simple trigger mechanism was installed.

It will allow a very strong rubber to be pulled with 100 pounds of force and can be locked in one inch increments.



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boyntonstu wrote:5 Kg draw yields 100 M/s and 27 Joules!

Can you explain this noteworthy efficiency?

I don't get it.

The guy shoots in the so-called "butterfly stance". This means he folds out his arms really wide, and the draw length is far (160 cm wingspan).

In this style, you can not use heavy bands as the finger position is awkward.

But the looong accel phase will propel the ball to high speed even though the draw weight is small. The rubber simply has a long enough "runway".

Ain't rubber a fascinating material?

JoergS wrote:

boyntonstu wrote:5 Kg draw yields 100 M/s and 27 Joules!

Can you explain this noteworthy efficiency?

I don't get it.

The guy shoots in the so-called "butterfly stance". This means he folds out his arms really wide, and the draw length is far (160 cm wingspan).

In this style, you can not use heavy bands as the finger position is awkward.

But the looong accel phase will propel the ball to high speed even though the draw weight is small. The rubber simply has a long enough "runway".

Ain't rubber a fascinating material?

This is very interesting.

Theraband specifications indicate that the % elongation determines the force, independent of the beginning length.

Acceleration = Force/mass

Velocity = acceleration x time

You indicate in the video that your bull pup is as powerful as your longer crossbow rifle. Please explain?