Inswinger crossbow (Rubber powered)

Here is my one version of the "in-swinging,springs (rubbers) propelled crossbow". It came from various inspirations like: oss William tell, French ww1 grenade launcher,manubalista etc...
The mock-up.



The test bench



The draw length: 18"



Next step is to put the rubbers and the winding-drum under the side
frame and the levers in the upper side of the frame. I actually use only
two packs of 15 rubbers but i can put lot more i will see that letter
on. I will probably use this trigger assembly:

Wow them German's are very clever and they make gorgeouse hunting crossbow's.It goe's to show that a crossbow can be made in many different way's and hey i just adore them all.Your design look's very interesting and so different from most other design's and i think myself that it could develop into something pretty awesome and the trigger assembly look's like a very nice machanism.I hope you keep on with this project and take it all the way as i would love to see what it can do when all done to absolute perfection and i think it will really be a good thing,hey we are all doing our bit to make it all that bit more fun and excitement and i think it keep's us all young too he he i never want to grow up ever i want to stay a kid as it is way more fun,let's play crossbows forever,man we rock we love it.

Prototype progressing well. Of course new problems emerging ,i am short of alloy then i use plywood but not strong enough,i will have to rebuild the swinging arms whith steel (kind of heavy) the trigger assembly work well,the new design lot better and very promising .

Hey Jeep. I see your work is coming along very nicely and nice to see another inswinging fan.

You asked if there was any disadvantage to moving your cams apart. What it does do is change the ratio of "arm" length to axle to axle distance. You are as close to a two to one ratio as is, but I think you will find a few advantages for a three to one ratio which can be accomplished by either widening the "riser or putting more distance between the axles OR, you can simply shorten the length of your arms.

The only "disadvantage" is that you will lose draw length on both top and bottom, but is offset by the perks. Happily the loss in draw can also be offset by adding some additional rotation (5-10 degrees?) to the machine and moving the "riser" forward a corresponding amount to length taken from the lever.

Shortening the levers or arms means you can get both more power and speed from the same basic setup, but also changes the stress on the machine.

Nick at wattsunique.com is about ready to test the new build (extra 15 degrees rotation from standard "hatra" arm rest position, and should get about 425 although I have calculated 450 to 460fps should be possible.

Keep up the great work.

I spend some time to improve the model changing the wooden arms for steel then reshaping them ,building a spanning winch. Like warhammer suggest a shorten the arms and the draw length to get more speed,and at last painting and varnishing a bit.

A red dot is more appropriate then a scope. The winch is in position, it can stay there ore to be removed

,The winch handle .

The winch url=https://servimg.com/view/16369594/69][/url]

The latest version:,

Jeep DUDE!!

Nice work. Coming to the arbalist guild is always so encouraging. I often get so discouraged I dont post much, but have made some real headway to actually get an "alternative powered weapon" to market. If everything goes right over the next few months, I get a real chance of having my designs showcased at the upcoming ATA in January with not one but possibly two leading crossbow manufacturers!

You are a work beast! Your design is so very close in many aspects to what I have planned. I cannot share too much information for now as I have attracted investment, but once the IP part is done and I am protected I would be pleased to share what I can.

I sent Ivo a vid of the latest build video and showing performance levels shooting arrows ranging from 270 grains through 1280 grains!!

On a return basis my designs are returning better than 3.5 fps per lbs of pull. Thats better than Scorpyd or any other bow out there for that matter.

What is exciting that I have attracted both licencing interest AND investment interest in my proposed "alternative powered" recreational and hunting weaponry.

What this means is that eventually I might be able to come out with some of my more advanced designs with higher fps potential.

Phil, if you read this we should advance our communcations to work together in promoting and establishing a"alternative powered" weaponry market. Its a wide open market.

PS - technology developers should get to know about Obama's patenting reform laws, and how it effects them..

W.

Thank Warhammer This model is only a bench test .Since I try it and finally one side exploded under pressure .The reason is not the concept but the quality of the materiel i used ,all the component (except rubber ring) are scrap material pic-up here and there!!!.I need to use welder to bent ant weld . I will also change the design to be less cumbersome. This model is very promising!! Now i know exactly what to do and where are the problems.The top way would be using composite material but i am not equipped for this, but fruit wood will be also very nice and warmer!!!

Jeep,it is looking good and i know how frustrating it can be when thing's go wrong or break but keep with it and maybe thicker stronger component's like hardened bolt's or other could work well.And as it develop's then new way's emerge to enable higher power and performance.But you now have a good platform to work from so go for it as i want to see this thing in action and i think it could be awesome when you get it all dead right.Joel yes we need to communicate more just email me anytime on either talismancrossbows@hotmail.com or info@talismancrossbows.co.uk and we can talk, or i can email you. Congratulation's on your success with your development work and on the investment side of thing's as it take's a lot of endless testing time and patience to get there and also i am very pleased with my project too as it is really coming together better than i had hoped and i am constantly looking at different way's to make improvement's on this thing and i also want to get a video or two onto here to show how it all perform's but have not had the time due to getting thing's all done but i will very soon,hopefully in the next day or two.

Nice vid but wheres the chrony????Argggghh.

Derrick was over today and I showed him. I think he liked it. There are still a few T's to cross and I's to dot, but looks like Im making solid progress. All going as planned so far despite minor glitches and changes I have made to accomadate for financing.
One more hurdle before final approval for funding. Im working hard at it tho.

I'll email you from my regular hotmail account tomorrow for a full update.

Almost forgot Jeep, was expecting that failure sooner or later. Mostly comes when ya wanna put an arrow on the deck and test fire it LOL.

Keep in mind the cam/pulley radius to overall lever length. Your cam may be a little too big but its hard to tell from the pics without dimensions.

Yes i know i will video it being chronographed when i am certain this chrono is reading true as i am pretty certain it is in need of calibrating and i will get this done asap.Right now i am getting all the cast part's to fit perfect and it is a lot of tediouse time consuming work but it is all coming together very well.I want to do another video with broadhead's soon and i will arrange to go to Quick's archery in Honiton Devon and take my chrony and see if it is spot on.Hoping to do this in the next couple of week's,anyway it is all good,wish i had a magic wand at time's as it is taking longer than expected but it is all good fun,Phil.

Hi Phil,hi Warhammer,
I am still experimenting: one after the others most of the components fails!!! But the basic idea and concepts are very valuable (rubber,inswinger...) I am already to second and half versions, improving shape and parts. The one now is all different but but all the same....Pictures soon if it don't blowingup again!!!
Plainly interesting post about spring propulsion.A lot to learn!!!

Knowing the strength or stress limits of the material you work with is key to progress. Then you can start working within the materials operating range - design optimization.
If you dont do that, you can perhaps have a never ending build cycle...

For what its worth, design tweaking never ends anyhow, and the main thing to never to lose sight of is that it should always be fun. A challenge perhaps but not a chore.

I look forward t seeing your next build.

Here is my second model, following the same bases: In swinger and rubber propelled.. I choose the bull-pup design, it is an obvious choice for a so long draw-lenght .It's compact and very well balanced : 25 " long for 16" draw.

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I put stronger rod for the came axes and change there angle. Test tomorrow ,at least you can see some pictures before new eventual failures. That is part of the game !!!! But each time is a new step to succes....I will try a video and try to post it .

Very nice Jeep!
Yes, the bullpup design is very nice and feels good bringing it to shoulder. I have been using a Jennings Devastor (just trashed the riser and limbs) and its a hard design to beat for compactness. Only thing is the weight.

One thing I'd like to try is the same devastor dimensions but with a Middleton custom rail and trigger with linkage. I think running the rail well past the trigger like the Darton models do will allow a nice shoulder butt piece, as well as provide a nice surface to put a cheekpiece on if needed. If one used a laser mounted underneath or onto the front foregrip, you would only need to point and shoot without bringing it to shoulder.

The other nice thing is its perfect for a tree stand. The high scope allows you to rest your elbow right on the knee and not have one of those knee rests to tote around.

The Devastor bullpup design is hard to beat for the long draw inswinger. I have a second Devastor coming as the first fell victim to a need for parts on another build. Our builds will look very similar when all done, much like the Middleton and Excalibur, Maximus recurves. More or less a natural progression I imagine.

This build is ever so much nicer than the first, and looking oforward to testing results.

W.