# Frankenbow do's, don'ts, and questions



## b0w_bender (Apr 30, 2006)

Don't over think it.
Build one and see what ya get. part of the fun of the frankenbow experience is the learning how things work through experimentation. 
I've put some super whacky stuff together and some of it is idiotic while others are OK. Most of the time I take them back apart and try something else. it really is a great way to learn why things work the way they do. Learn by doing.


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## Onza (Jul 17, 2005)

Just dive in. I've built numerous frankencarnations of my Onzas and each one has been unique. After a few iterations, I've found a combination of limbs and cams that I like. The biggest issue for me is that I don't do strings, therefore I have to figure string lengths by knotting an old set of strings and then have them made, thus delaying the project...but each has been worth it. 

With regard to you question about cam and idler selection, the idler diameter must match up with the single cam to make sure the string is parallel at rest to the bow. If the diameter is too bit or small, it will result in an angled string.


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## B.Hunter (May 4, 2009)

Above 2 responses are correct and are good info. Trial and error. You learn as you go. You will soon figure out what will work and what won't. I have found that keeping some "old" different length strings/cables can be twisted/untwisted to help in determining lengths needed on frankenbows. You can always ask questions if in doubt-there are no "stupid" questions. When using dual cams, make sure the limbs were designed for them-I tried some aggressive dual cams on limbs designed for single cam, it didn't survive the test!


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## dfII (Aug 2, 2012)

Thanks for the responses. I am getting excited about trying this and there are alot of parts and info on here that should help. Once i finally get to it i'll be sure to post some stuff.


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## GrayTech (Jan 29, 2013)

Onza said:


> Just dive in. I've built numerous frankencarnations of my Onzas and each one has been unique. After a few iterations, I've found a combination of limbs and cams that I like. The biggest issue for me is that I don't do strings, therefore I have to figure string lengths by knotting an old set of strings and then have them made, thus delaying the project...but each has been worth it.
> 
> With regard to you question about cam and idler selection, the idler diameter must match up with the single cam to make sure the string is parallel at rest to the bow. If the diameter is too bit or small, it will result in an angled string.


Granted the idler size is quite important, but quite a few bows I've seen have a slightly angled string, my redhead kronik, built by bowtech, is set up like that. Maybe that's one of the reasons it's a tricky sob to tune.


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## b0w_bender (Apr 30, 2006)

GrayTech said:


> Granted the idler size is quite important, but quite a few bows I've seen have a slightly angled string, my redhead kronik, built by bowtech, is set up like that. Maybe that's one of the reasons it's a tricky sob to tune.


Genesis bows are for sure angled.


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## dfII (Aug 2, 2012)

That's interesting. I have a mathews idler and a spare insanity cam. The size is close depending on where you look at it. Still alot to consider. Haven't got all the way into looking into axles and all that. Still working on my string jig so some things are going to have to wait. Any and all info is appreciated guys. I've come a long way thanks to this site, although sometimes the more i learn the more confused i get if that makes any sense.


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## dfII (Aug 2, 2012)

What affects the draw length change when putting a bow together? Is the ata the main part or ata and brace height or is there more to it? Let's say you have a set of cams that made a bow 27 inch draw on a 31" ata bow with a 7" brace height then put those cams on a 33" ata bow with a 7 ish inch brace height. Does anyone have an idea on what the draw lenght would become on something like that? I know there are alot of guys that have done this stuff and there has to be some info on that.


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## apamambax (Dec 23, 2009)

dfII said:


> That's interesting. I have a mathews idler and a spare insanity cam. The size is close depending on where you look at it. Still alot to consider. Haven't got all the way into looking into axles and all that. Still working on my string jig so some things are going to have to wait. Any and all info is appreciated guys. I've come a long way thanks to this site, although sometimes the more i learn the more confused i get if that makes any sense.


except you can't use a dual cam and make a single cam out of it..You will need a second feed out track.....Ive tried making twin tracks out of dual cams that never wanted to stay timed...loses poundage like you wouldnt believe so I scrapped...


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## dfII (Aug 2, 2012)

That makes sense. Like i said i'm just getting into this and want to think some of it through before attempting it. I figure by the time i get one or two of these built i should actually understand the way it all works. As of right now i don't get alot of it unless i keep referring to a nuts and bolts print out or help from you guys.


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## Steve Jo (Feb 7, 2008)

A couple parameters I used for figuring mine. Now mine was simple, I wanted to go from a Mathews Q2XL cam system and put Spiral Cams on it. Pretty simple on a difficulty scale. 
I found a hoyt bow with a similar ATA - both the hoyt Pro Elite and the Mathews Q2XL are roughly 38" ata. So that means the sting, bus and control cable can essentially stay the same length making the process a bit easier.
The first measurement is the axle to string distance on the new cam system you are putting on your Frankenbow. In this case, a spiral cam. You need that ebcause that will determine your new brace height
One you have the bh, in my case 6.5" you need to deduct that from your target draw length (29.5") to get get your power stroke. My target was a 23" power stroke in a spiral cam.
take that 23" power stroke and add it to the BH of the donor bow. In this case, 8"
8+23=31"
My target was a number 6 spiral cam. I made the strings before the cams arrived and it all fit very well



dfII said:


> What affects the draw length change when putting a bow together? Is the ata the main part or ata and brace height or is there more to it? Let's say you have a set of cams that made a bow 27 inch draw on a 31" ata bow with a 7" brace height then put those cams on a 33" ata bow with a 7 ish inch brace height. Does anyone have an idea on what the draw lenght would become on something like that? I know there are alot of guys that have done this stuff and there has to be some info on that.


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## redyak3 (Nov 5, 2011)

Steve Jo said:


> A couple parameters I used for figuring mine. Now mine was simple, I wanted to go from a Mathews Q2XL cam system and put Spiral Cams on it. Pretty simple on a difficulty scale.
> I found a hoyt bow with a similar ATA - both the hoyt Pro Elite and the Mathews Q2XL are roughly 38" ata. So that means the sting, bus and control cable can essentially stay the same length making the process a bit easier.
> The first measurement is the axle to string distance on the new cam system you are putting on your Frankenbow. In this case, a spiral cam. You need that ebcause that will determine your new brace height
> One you have the bh, in my case 6.5" you need to deduct that from your target draw length (29.5") to get get your power stroke. My target was a 23" power stroke in a spiral cam.
> ...


Saw this earlier and really got me interested. I'd like to make a franken dual cam z7... is that even possible...


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## Steve Jo (Feb 7, 2008)

What cam system do you want to use?
I went with the Spirals because I have shot them and really like the draw cycle, the solid wall and the ease of tuning.


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## Tunaboy (Oct 3, 2004)

Steve could you explain how you came up with the # 6 spiral can? Very interesting responce. I am looking at putting spirals on an Alpha-Max 35. The right spiral cam would be the big question. Another plus would be to get the new strings close to the correct length. Yours is the first post I have seen about how to make these decisions on cam swaps. Thanks


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## Steve Jo (Feb 7, 2008)

Tunaboy said:


> Steve could you explain how you came up with the # 6 spiral can? Very interesting responce. I am looking at putting spirals on an Alpha-Max 35. The right spiral cam would be the big question. Another plus would be to get the new strings close to the correct length. Yours is the first post I have seen about how to make these decisions on cam swaps. Thanks


I have no idea if this is right, or even helpful. This is the first time I have attempted a build or even really thought about it. I didnt read anything as far as a how to, I had it in my head how I wanted it to go from the beginning. This is how I did it. I hope it helps

Like I said, I kind of cheated or at least took a huge shortcut by finding a hoyt that had a similar ATA. there are a lot of hoyt configurations and so doing this should be the first step if you are planning on using hoyt cams as it greatly simplifies the build by taking out much of the guesswork on string and cable lengths and all that those variations can do to influence draw length.

I dont have the bows sitting here in front of me to reference the exact measurements so this will be examples only.

AXEL TO STRING - The foundation of the frankenbow was a Q2XL, I believe it has a starting BH of 8" or something like that with its ATA at 38". 
Measure the Axle to string and record it. we will say it is 2"








That 2" axle to string measurement is directly contributing to the 8" brace height of the Current cam system

Now measure the Axle to string of donor cam set, in this case a SpiralX - for the sake of easy math, we will say that this measurement is .5"








When you put the new cam system on the brace height will be shortened by an inch and a half (Old Axel to string minus new axel to string 2-.5=1.5)

Now deduct the 1.5 from your current brace height of 8 (8 - 1.5 +6.5") 6.5" is your new brace height.

Now we need to determine the length of power stroke (not sure if that is the right terminology, but it is the amount of draw from brace height to full draw to achieve the desired overall draw length) In my case, I have a 29.5 in draw. So take 29.5dl - 6.5bh = 23" powerstroke.

Now go back to the Hoyt donor bow and add 23" to that bow's brace height (8") - 23 + 8 = 31. You need a Spiral cam that will give you a 31" draw on an alpha elite. 

Looking at the hoyt tune charts, that cam is a Sprial x 6.0

Hope that helps, please feel free to ask more questions, I will help where I can.


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## redyak3 (Nov 5, 2011)

^^^ 
Very informative, thanks...got to do more research.


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## Tunaboy (Oct 3, 2004)

Hey thanks Steve,
This last post with the pics helps a lot.

Tuna


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## dfII (Aug 2, 2012)

Thank you. This thread has truly just become a useful tool thanks to you guys.


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## Steve Jo (Feb 7, 2008)

Glad I could help.
As I said, looking for a donor bow with similar ATA is decidedly less complicated. The real franken people would have to help you with a build like that.


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## dfII (Aug 2, 2012)

Got started on the build last night. Made a half decent first time string. Got to make cables tonight. Any suggestions on where to find spacers and such for the cams? I'm thinking ace may just be the place. What materials work best for that? Hard plastics or teflon seem like they would wear easier but also wear less on the more major components. Getting string and cable measurements is alot harder that i first thought it was going to be. I'm not dead set on the bow where it is now but it's looking like it'll be about a 8" brace, 33 ata, and with the cams i have most likely going to be way too long for me. I'll shoot it before changing it anyway and get some pics on here. I'm enjoying the challenge.


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## Tunaboy (Oct 3, 2004)

OK I start with 2 bows that are pretty close on A to A's and brace. If I understand this correctly I can take the known length strings and put them on the frankin bow. At that point I check the A to A and brace and compare that to where the bow should be and calculate how long the final string set needs to be. Making several sets of strings before I get them right is not my idea of fun. Being able to get lenghts right would be big. Does this sound reasonable?


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## apamambax (Dec 23, 2009)

if the cam size is between string and axle in a resting position it will change the brace height and also the draw length....


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## apamambax (Dec 23, 2009)

did anyone ever take a mathews bow and put a left hand cam at the top to form a dual yoke true duel cam...some of them you can remove the second string track so you wouldnt have that xtra weight....also you could do the same thing with bottom hybrid cams


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## dfII (Aug 2, 2012)

Ok. I have made some progress now. I have a maitland kinetic six riser. PSE supra max 70 lb limbs. Hoyt vxt #3 cams. Not sure which mod. 34-1/4" ata, 7/5/8 brace height. But the cams aren't in the starting position i need them to be yet so that'll need to change. Made strings and cables. Will be reworking alot of it. I have shot the bow once which i thought was cool even though i shouldn't have yet since i had more cam lean than i like on the bottom cam. There are yokes on top but not the bottom so i've found that by moving the cam on the axle side to side will affect the cam lean. The maitland riser is set for the limbs to be 1" apart and there is alot of room on the axle for the cam to be moved. I'm not sure if this is the correct thing to do. So now i know you can change cam lean without yokes although it affects enter shot but it seems those two will come together when i get it right. So far i think i've learned alot in some areas or at least have more of an idea what to look into and study on this stuff.


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## dfII (Aug 2, 2012)

apamambax said:


> did anyone ever take a mathews bow and put a left hand cam at the top to form a dual yoke true duel cam...some of them you can remove the second string track so you wouldnt have that xtra weight....also you could do the same thing with bottom hybrid cams


I'm not sure i understand what you are saying really. I need to look into definitions of hybrid cams. Are hoyt xtr's hybrid. So are you saying i should be able to make a yoke on the bottom and top by doing this? Would it have to be a left hand cam if so or does that only apply to single cam applications. I'll look at it all when i get home and try to figure it out. This could be great.


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## apamambax (Dec 23, 2009)

top would be left hand.....for single cam or hybrid cam


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## dfII (Aug 2, 2012)

Now i am at a standstill. I have no idea where to position the cam to start. I've tried using pictures of the maxxis as a reference but my limb angle is quite alot different in relation to cam and string. So, back to tying knots and connecting strings and such to try to find the right length. It's all fun though. For some reason i like a struggle or challenge like this.


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## apamambax (Dec 23, 2009)

this is an advantage for you...part of frankenbow fun....you can rotate cam forward or backward to get the force curve you want...it works best to have a draw board with a scales on it


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## b0w_bender (Apr 30, 2006)

dfII said:


> Now i am at a standstill. I have no idea where to position the cam to start. I've tried using pictures of the maxxis as a reference but my limb angle is quite alot different in relation to cam and string. So, back to tying knots and connecting strings and such to try to find the right length. It's all fun though. For some reason i like a struggle or challenge like this.


And when you are done with all the fooling around you'll have a greater satisfaction for learning something new and you'll be much more likely to tweak your next project because you understand the process sooo much better. Thisd is what makes the DIY and Frankenbow process enjoyable. You get a product customized to your specific preferences and specifications. Well done.


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## dfII (Aug 2, 2012)

Thank alot guys. Here are some pics real quick. I been shooting it with the string i built on the jig i built and put together with the press i built all from help on this awesome site.


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## redyak3 (Nov 5, 2011)

Nice job dfII!!! The DIY site here is priceless!


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## B.Hunter (May 4, 2009)

Very cool dfII


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## dfII (Aug 2, 2012)

Thanks again. I'll be trying a two color string this week for the first time i think. Can't wait for that. Got to paint the string jig and clean up the garage and i hope to get some more pictures up on here of the progress. I wouldn't be doing much of any of this without the help of A.T. members. I have learned more in the last two weeks than the rest of my life on this stuff and i love it.


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## 13bonatter69 (Dec 23, 2007)

Franken Bows are very cool


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## dfII (Aug 2, 2012)

Got a little more tuning in on it today and improved the time/sync alot as far as eyeballing goes. I'll have the draw board built soon so i can take it all a step further and do a better job on all this. I nicked one of my cables somehow and have a couple strands broken, the same cable that was a hair short anyway unless you take all twists out, so i am going to make a new one and try a two color cable for my first attempt at that. I'll have an oddball cable but that kind of suits a frankenbow anyway i guess.


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## dfII (Aug 2, 2012)

Any tips on where to get spacers for axles or other axle parts.


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## b0w_bender (Apr 30, 2006)

dfII said:


> Any tips on where to get spacers for axles or other axle parts.


McMaster Carr they have a pretty good selection of plastic spacers


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## dfII (Aug 2, 2012)

I got some white and some black nylon spacers at ace but i am wondering if there is a better suited material or if nylon is good.


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## dfII (Aug 2, 2012)

Got a stabilizer mount chrono from a guy on here and i think it's really close to being accurate and it shows 299-301 repleatedly with a 28", 376 grain arrow (weighed with tip, vanes, and everything) with the bow i built. The one in the pictures above I think it's close since it shows my insanity at 337-340 repeatedly as it did at a shop with the same setup as now. I'm pretty excited about the speed i'm getting with a 34.5" ata, 7-5/8 bh, 31" draw. The draw is too long for me and i'll be changing cams soon so i know i'll lose some speed but it's still awesome. This thing shoots so nice and is very very quiet.


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## dfII (Aug 2, 2012)

Got a second one done. Pics soon. This one is alot cooler.


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## CarbonWarrior (Apr 12, 2014)

Sounds like youre getting good at it. I am also in the process of a Frank with a Maitland riser as a base. PRIME Pct will be my cams of choice. Still a little unsure on the limbs... we'll see. Cant wait to see your pix.


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## deerhuntin24 (Mar 4, 2014)

Very Cool! excited to see your next one!


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## JBaker1 (Aug 4, 2014)

I am curious has any of you FRANKENBOW builders taken a solo cam like a Z7 and turned it into a dual cam? If so what kind of performance 
did you get? I have 2 of them and was thinking about tinkering with 1 but I am not that bow savey.


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## CarbonWarrior (Apr 12, 2014)

JBaker1 said:


> I am curious has any of you FRANKENBOW builders taken a solo cam like a Z7 and turned it into a dual cam? If so what kind of performance
> did you get? I have 2 of them and was thinking about tinkering with 1 but I am not that bow savey.


I was thinking of doing the same with my Halo 31... taking 2 Creed cams and making a dual out of it. Jim (MxTuner) warned me though... it may be nearly un-shootable because 2 solo-cam's together tend to end up with over a 90% letoff... even worse than an Overextended Elite without Draw Stops. LOL... I may still give it a try... but, you've been warned, as have I.


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## dfII (Aug 2, 2012)

Awesome. This Is a fun thread. I'll post pics tomorrow if I remember after my frankenbowfishing shoot. My maitland-pse-prime is wicked. Should probably use it for something other than bowfishing but the girlfriend has claimed my other rig so that's what I've done with it


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## dfII (Aug 2, 2012)

Can't s seem to upload pictures from my phone so it'll be a day or two.


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## dfII (Aug 2, 2012)

Not the best pictures but there it is. Bloody arrow and all from the carp shoot.


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## dfII (Aug 2, 2012)

CarbonWarrior said:


> Sounds like youre getting good at it. I am also in the process of a Frank with a Maitland riser as a base. PRIME Pct will be my cams of choice. Still a little unsure on the limbs... we'll see. Cant wait to see your pix.


Not sure what other limbs can be used for them but this has gone well so far. Only shot a bare shaft off that bowfishing rest outside of bowfishing but it was oddly quiet and smooth on the release. Like i said before the girlfriend claimed my other bowfishing rig so this had to be done. Pretty sweet rig for bowfishing for sure.


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## JBaker1 (Aug 4, 2014)

Thanks for the infomation, thought it would be a cool project. I may give it a try, even at 90% I can still shoot it.



CarbonWarrior said:


> I was thinking of doing the same with my Halo 31... taking 2 Creed cams and making a dual out of it. Jim (MxTuner) warned me though... it may be nearly un-shootable because 2 solo-cam's together tend to end up with over a 90% letoff... even worse than an Overextended Elite without Draw Stops. LOL... I may still give it a try... but, you've been warned, as have I.


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