# Homebuilt bows



## UniGram (Dec 11, 2010)

I have seen a couple of really nice threads on homebuilt bows and just wanted to share my homebuilt bows. The only thing i cannot take credit for is the limbs that are from Barnsdale archery, thanks Dave. The bows have hybrid risers with lightweight material in the core. I will post updates shortly.


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## mike-E (Nov 12, 2009)

niiicccceee!!!! do you have machines at your house?


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## UniGram (Dec 11, 2010)

Rotated Picture.
And yes, I have a small cnc machine. I cannot take a full riser because it is 31,5". That is the reason for the bolted solution and because it would take huge inital aluminium Blocks.


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## Holo (Feb 12, 2004)

Looks great!
What is the ATA and brace of the longest bow you have designed?


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## turkeysroost (Nov 14, 2009)

UniGram said:


> I have seen a couple of really nice threads on homebuilt bows and just wanted to share my homebuilt bows. The only thing i cannot take credit for is the limbs that are from Barnsdale archery, thanks Dave. The bows have hybrid risers with lightweight material in the core. I will post updates shortly.
> View attachment 2134382


That's real slick!


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## Mickeyj74 (Dec 16, 2014)

That is truly awesome. How do they shot?


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## brad canton (Feb 4, 2010)

do you have a website looks sweet


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## UniGram (Dec 11, 2010)

Specs for the bows as they are today
ATA 36"
BH 6,5" regular cams
Weight 4,85# (31,5" riser shoot thru)
Right now the bows are disassembled for transport but I will reassemble one of them for myself shortly for test shooting.


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## Luke M (Aug 24, 2012)

Looks awesome! I have been wanting to build a riser and build from there but like you its a large block and I cant do something that large. I like the bolt together method you came up with! Was it cost effective with buying the other parts and aluminium block?


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## UniGram (Dec 11, 2010)

Yes compared to one full block, compared to what you can buy an top brand bow for, NO!


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## aread (Dec 25, 2009)

Thanks for posting. Those look great.

Please post more photos when you get them re-assembled.


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## UniGram (Dec 11, 2010)

I will do a revised DFC shortly, but for now here are some more Pictures of the reassembled bow, first a Picture of generation 3, which was approx. 30" ATA and 6,5" BH.


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## UniGram (Dec 11, 2010)

*Pictures*

Next Pictures are gen4. 
36,5" ata
6,5" bh
52#
Customized with my name on sideplates.
Pay attention the riser, the core material is replaced with lighter weight nylon.


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## YBSLO (Nov 3, 2005)

If you were to swing the dollars for the price of the full block could you machine half this on a pinned fixture and re-position & then machine the other half?
Providing your machine is open. 
1/2" pins could be your locators? After roughing one may install 3/8" or 1/4" pins for semi finishing & finishing? 
This might reduce some weight and keep a slimmer profile?

Your fixturing does not need to be full size...Lay plates down and mount to the mill bed and mill them parallel to the machine head then fixture from there.
Providing this does not create to much vibration?

But then again you probably know all this...Looks like your very skilled already!

This looks really awesome!!!! Nice Job!!!! I like the nylon...Good idea!!!

Again Way Kool!!!!


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## Luke M (Aug 24, 2012)

What are you getting for speed, let off, and vibration with that 52# draw? Do you think that would hold up to something around 70-80#?


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## snapcrackpop (Nov 15, 2010)

So is this for "fun" or what advantages does it have over current brands?
Looks like great work so far.


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## UniGram (Dec 11, 2010)

View attachment Trækprøve ug4.xlsx.pdf
The bows have 3 distinct different Technologies/ideas. 
1. The hybrid risers which potentially will lower the weight of the risers by a good amount but I will need more Work on them before it can be harvested. Right now the bows are 4,85# which is actually comparable to other shoot thru bows. 
2. in Denmark special order bows are 8-12 weeks, so my idea was to add customization in specific sections which do not compromise the risers strength. For instance the shown bow has my name on it. 
3. One of the bows is built with reverse cams, an idea on achieving higher speeds than seen today (that one will need a lot of Work to finalize).

The bows are built to show craftmanship, ideas and commitment. 
I am not a machinist and had never operated a cnc prior to Building the gen4 bows 6 month ago. I am however and RD engineer and hope someday to combine my job and passion:wink:

Attached is DFC for present bow, I can actually get the front and back end of the cycle more inline, just did not get around to mapping it. I can adjust let off with the size of the stop pegs, believe its around 80% right now. And I need to verify the design with strain gauge testing before going to higher Draw weights, but it should not be a problem to reach 70#.


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## aread (Dec 25, 2009)

Those are really great! Good work!

Those are excellent quality for home built bows, even approaching that of the factories.

I'd be really interested in seeing where you go with the composite riser. That has some real possibilities.

Thank you for posting!

Allen


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## Luke M (Aug 24, 2012)

I really like that 36.5" ATA bow, put a string stop on it and it would be sweet! Would you mind me asking about the dual cables? If you were going to "sell" them what would they go for?

I cant get over the white and silver combo, I like it!


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## UniGram (Dec 11, 2010)

I got around to firing the bow for the first time ever. One thing is theory but another is actually shooting the bow. But it was not without some nerves. Just to be a bit safe the bow was shot with a 650 grain arrow for now. 
http://youtu.be/tHLFlsbJ82M


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## RatherBArchery (Oct 31, 2006)

I would think these could be cut using a waterjet instead of mill?? Think that would save $$$?? Load a 4 x 8 plate of aluminum and cut a bunch of parts at a time. Would cut the plastic too.


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## UniGram (Dec 11, 2010)

You are right. As I ran out of time I decided to have the top, bottom and grip laser cut. But for the sight window it does not make a Whole lot of sense.


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## RatherBArchery (Oct 31, 2006)

That bow caught my eye at the ATA for sure!!


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## UniGram (Dec 11, 2010)

When we returned from the ATA, I promised my wife to take a break from bow Building. 
14 days have passed where I have only made som napkin sketches and now its time to look forward.
The Gen5 (name suggestions are welcome), will be a complete new bow (what is the opposite of a shoot thru riser?)
I would like input on what the bow should be, my own idea is.
Hunting bow
30-32" ATA
25-27" riser
BH 6 or 7
IBO 330
Weight extremely low, but with the option of adding weight at the bottom of the riser.


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## RatherBArchery (Oct 31, 2006)

Maybe this is your plan but I would stick with the same 'mid frame' design and just make the upper and lower different to change up ATA and brace. That way if you get into production there would be less machinery changeover for different bows. Why not a shoot thru hunting bow with only the standard cable set-up, this way your not feeding broadheads thru cables  Save the shoot thru cables for the target bows. Just my $.02


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## BigBuckDown! (Jun 22, 2012)

This is awesome work! I am so excited to see what you do with the gen 5!


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## smokin x's (Apr 30, 2007)

Those bows are pretty cool! 

Another good reason to keep the same mid section would be options of selling a quality 2 in 1 bow. Make bows of different ATA, brace height, etc.

You could get a short ATA higher brace bow for hunting and buy longer upper and lower sections, and possibly limbs (same cams maybe?) and have a longer ATA, shorter brace height and faster target bow.


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## Jleblanc603 (Jan 28, 2015)

Wow, seems to shoot great too. Def gonna keep my eyes on this thread as you continue these amazing bows. Congrats on a unique setup of your own...


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## MikeR (Apr 2, 2004)

Nice work, I'll be interested to see how this evolves.


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## UniGram (Dec 11, 2010)

First concept drawing for the riser that makes up gen5 has been sketched.
Gen5 will be about pushing the Hybrid riser technology as far as I can.
The riser is made up from 2 skins both made from 3 mm (approx 1/8") in 7075-T6 aluminum
The core is made up from EPP 60 g/l.
The total weight of the riser will be around 1#, where current alu risers close to 2# I weighed the riser of my 2013 PSE Vendetta DC and the riser was 2,07#
The sketch is just loaded with 2.500 N = 560# showing that is should hold up quite well.
I know the Picture is quite small, the Von Mises loads in the riser are well under 100 mpa, which should be no issue for 7075,


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## BluMeanie (May 5, 2014)

I am absolutely certain the "big names" are truly grateful you are doing all this materials-engineering and research. It will save them _MILLIONS_ in the long run...

:devil:


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## UniGram (Dec 11, 2010)

The hybrid solution is protected, and there is a lot of know how that is different from Common practice. But maybe you are Right, but as the hybrid riser was presented at the ATA it is no longer to be considered a secret.


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## silasvirus82 (Jan 5, 2012)

pretty cool. good luck with your project. I think the ability to customize the riser will be attractive to certain buyers, mainly the target crowd. Find yourself a good finishing shop to team up with and provide some really custom looks.


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## HeadKnock (Feb 22, 2015)

This bow has a unique symmetry that would allow it to be both left and right hand (assuming no custom handle add on). 

I'm curious, with this symmetrical approach, what might be done with a centered sight sitting in the center of the "shoot thru riser". Peep could be the same (of course). Even if all the contributing factors (release, rest, torque) are equal, or negated, there would have to be some sort of allowance for wind.

This could open new possibilities for sight design. If the riser is the right width, traditional sights could still be used, but I wonder what someone might be able to do to take advantage of the symmetry?


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