# Compression Spring for string jig



## Raymond 1 (Feb 23, 2010)

Hey Folks,
I have a Munch String jig and stretcher unit. I would like to put a compression spring in the unit. People suggests a spring with a minimum amount of 300 lbs of tension from a compression spring. I have found a 3 1/2" red compression spring for sale with these specifications and was wondering if there is a formula that can be used to figure out if this compression spring will give me the 300 lbs of tension that I need for my Munch string jig and stretcher unit? 

The specifications are as follows:
Compression Die Spring
.606" Outside Diameter
.353" Inside Diameter
length - 3 1/2" 
Color - Red
Gage - .093"

Thank you,
Raymond


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## Rageking (Jan 15, 2012)

I bought a munch stretcher 6 months ago and started to use xs2 sting material and found that his stretcher is not strong enough. The posts just bent together after i tried to putting tension on the string.


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## nuts&bolts (Mar 25, 2005)

Raymond 1 said:


> Hey Folks,
> I have a Munch String jig and stretcher unit. I would like to put a compression spring in the unit. People suggests a spring with a minimum amount of 300 lbs of tension from a compression spring. I have found a 3 1/2" red compression spring for sale with these specifications and was wondering if there is a formula that can be used to figure out if this compression spring will give me the 300 lbs of tension that I need for my Munch string jig and stretcher unit?
> 
> The specifications are as follows:
> ...


Hello Raymond:

http://www.mcmaster.com/#cadinlnord/9584k67/=j8jagc

Use McMaster Carr Part No. 9584K67.

Outside diameter = 1.25-inches
Inside diameter = 0.625-inches

2-inches long

RED spring color code
Max deflection = 20% of unloaded length.

MAX load = 346 lbs when you hit the 20% reduction in original length...
so basically,
a 2-inch long spring,
do NOT squeeze down more than 0.4-inches.

You should hit 300 lbs of load BEFORE squeezing down 0.4-inches...
so somewhere around 5/16ths - 3/8th inches of SQUEEZE or less, you should hit 300 lbs of load.


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## dwagoner (Sep 27, 2007)

actually i would get a shorter and stronger spring, 2" long spring that you have to compress 20% will leave you with ALOT of twisting the ends of your stretcher jig, remember not only does the spring need to compress 20% but that equates to over 3/8" and also the string stretches, with a long single cam string your gonna have to tighten down a few inches on your eyebolts or however you stretch. i use a 1.25 HD spring thats 15% and it moves alot for me, ive tried 2" and 3" and there just alot of work to get up to strength. i use these springs and have found them the best of several ive used from mcmaster carr, plus a few bucks cheaper than the longer one posted above

PN# 9588K73
http://www.mcmaster.com/#cadinlnord/9588k73/=j8l80g


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## BC Bowstrings (Feb 29, 2012)

Rageking said:


> I bought a munch stretcher 6 months ago and started to use xs2 sting material and found that his stretcher is not strong enough. The posts just bent together after i tried to putting tension on the string.


I have 2 of his stretchers and have them over 300 lbs regularly, they don't move. Are you stretching with the layout posts?


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## bulkness (Jun 3, 2011)

I recently purchased one of Munch's string jigs. How do I use the springs if I purchase the ones listed in post #4? Do I purchase one or two? Thanks again Sasquatch


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## dwagoner (Sep 27, 2007)

your gonna have to ask MUNCH that, i build my own stretchers and i have a special way i build them to fit the springs, there not like his so cant say how you should use them....


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## Hoytalpha35 (Apr 5, 2011)

BC Bowstrings said:


> I have 2 of his stretchers and have them over 300 lbs regularly, they don't move. Are you stretching with the layout posts?


I was wondering the same. My stretchers mostly see a little over 300 and have had them close to 400lbs


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## Hoytalpha35 (Apr 5, 2011)

bulkness said:


> I recently purchased one of Munch's string jigs. How do I use the springs if I purchase the ones listed in post #4? Do I purchase one or two? Thanks again Sasquatch


You only need one per stretcher set.


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## Raymond 1 (Feb 23, 2010)

BC Bowstrings said:


> I have 2 of his stretchers and have them over 300 lbs regularly, they don't move. Are you stretching with the layout posts?


No, I am not using the string layout posts, I am using the stretcher posts. I have heard many may good things about Munch's string and stretcher jig.
Thanks for the information, much appreciated.
Raymond


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## Raymond 1 (Feb 23, 2010)

BC Bowstrings said:


> I have 2 of his stretchers and have them over 300 lbs regularly, they don't move. Are you stretching with the layout posts?


No, I am not using the string layout posts, I am using the stretcher posts. I have heard many may good things about Munch's string and stretcher jig. I have tightened the tension as tight as I can with the string stretchers and have had no problem with the setup bending. I would have to say that I am more than happy with my Munch String Jig. Thanks for the information, much appreciated.
Raymond


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## Rageking (Jan 15, 2012)

no i am stretching with the stretcher not the layout post. I first used 452x material worked find but when I used xs2 material it doesn't give, a little extra stretch I ended up bending the posts. They can be made a little stronger.


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## FS560 (May 22, 2002)

Rageking said:


> no i am stretching with the stretcher not the layout post. I first used 452x material worked find but when I used xs2 material it doesn't give, a little extra stretch I ended up bending the posts. They can be made a little stronger.


Are you absolutely sure that you did not bottom your spring? That will absolutely bend jig components within the capacity of the string and then and apply excessive stress to the fibers of the string itself. Once the spring bottoms, you have no idea of what you have.


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## bulkness (Jun 3, 2011)

If I use the spring, how do I tell when I have the spring compressed to the proper height?


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## dwagoner (Sep 27, 2007)

its a percentage of compression to get to its load, ie the spring i posted makes 321lb at 15% compression, SO 15% of 1.25" it gets to 321lb at 1.075"


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## bulkness (Jun 3, 2011)

Thank you very much dwagoner. I have a t-shirt that has your signature statement printed on the back. A very true statement.


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## dwagoner (Sep 27, 2007)

yep, after 12yrs in Army i live it to the max, i kinda wish i woulda still been in, always raised my hand when they asked for people to deploy, sorry i was a medal junkie and i would go anywhere and love it!!!!!


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## rhythmz (Jan 10, 2010)

Thanks Nuts & Bolts. 

I placed my order for this spring today. As always, you deliver the goods right on time. Thanks Brother!!! God Bless!!!


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## dwagoner (Sep 27, 2007)

RHY hope your happy with that longer spring, i found the longer ones to be a hinderance vs anything helpfull when stretching, when you use on a long single cam string youll see what i mean, if you dont like the amount you have to turn the ends to get up to poundage then try the shorter ones and heavier duty than the 20% ones


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## munch (Mar 27, 2005)

Rageking said:


> no i am stretching with the stretcher not the layout post. I first used 452x material worked find but when I used xs2 material it doesn't give, a little extra stretch I ended up bending the posts. They can be made a little stronger.


is there any way you can post the pics of the posts .ive had a 32 strand crossbow string doubled in the stretcher so tight i could stand on it and not bend it .would like to ship you some new posts if they are faulty .would also like to get the old ones back to figure out what happened.ive heard nothing back from anyone saying the post bent i'm cureouse if the aluminum supplier shipped the wrong material thanks and sorry i did not see this post ive been away moose hunting terry


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## rhythmz (Jan 10, 2010)

dwagoner, are you saying that perhaps the spring I ordered may not be best suited for string building applications? I'm new at this so real-world experience and knowledge is greatly appreciated!!!


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## Nitroboy (Jan 15, 2006)

I have a 3.5" spring rated at 300# at full compression and it SUCKS!!! I just ordered 3 of the ones dwagoner posted to use cause after you get to building a few sets it sucks to have to compress that much length, I built 4 sets today and am wore out from it, I get the new shorter ones in and it should be awesome!!!


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## dwagoner (Sep 27, 2007)

rhythmz said:


> dwagoner, are you saying that perhaps the spring I ordered may not be best suited for string building applications? I'm new at this so real-world experience and knowledge is greatly appreciated!!!


its just a PITA with longer springs, dont think your only gonna take that 2" you got and have to turn your eyebolts down only .4 inches. you have the string to stretch also, its just a pain to have to sit there and turn your end bolts like 2+ inches to get up to poundage. The one you got will work, IE i just built a 65" string and checked how much my spring had to have the ends turned to get it up to 350lb and it was like 1.5" of travel, when i build a long single string like 85+ inches i have to use all of the 2.5" of travel on my eye bolts to get it up to where i stretch it, next time you order just try a shorter one also and see how you like it, i think its way easier and ive used up to medium range 3" springs and now all i use is those HD 1.25" springs


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## rhythmz (Jan 10, 2010)

dwagoner, so you are suggesting that I set aside the spring I bought at the first part of this thread (part# 9584K67) for the spring you suggested (part# 9588K73)? THe suggestions initially I percieved was that I would only have to compress the longer spring approximately .4 inches to achive 300lbs. so I wouldn't have to tighten down too much. Did I misunderstand that measure?

Would your part suggestion provide a better compression (less work to get to 300lbs.)? I have no issues with ordering the spring you suggested...like most people, I would rather work smarter than harder!!!


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## diamondback21 (Oct 20, 2008)

Would this spring be ok? http://www.fastenal.com/web/search/product/die-springs/_/Navigation?searchterm=Die+spring&sortby=webrank&sortdir=descending&searchmode=&refine=~|categoryl3:%22601113%20Die%20Springs%22|~%20~|sattr02:^%22Heavy%20Duty%22$|~%20~|attrlength:1490|~%20~|sattr07:^1-1/4%22$|~%20~|sattr08:^%22154.0%20lb%20per%201/10%22%22$|~


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## Nitroboy (Jan 15, 2006)

Got my new springs in today the ones dwagoner recommended and all I can say is THANKS D!! I don't have to do hear the tightening to get over 300# out these springs!! ALOT better than my 3.5" springs


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## dwagoner (Sep 27, 2007)

get a set of calipers, the 15% load the spring will compress to 1.075 to get right bout 325lb I use a big flat washer on end of mine on my jigs, pretty thick or a few thin ones, and i measure from inside of washer to jig as my springs sit on the jig itself, works fine for me but after you do it enough you can get a feel when tightening the opposite end down and know when your close by just how tight the nut is getting, i can get it real close by feel, then measure.


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## dwagoner (Sep 27, 2007)

rhythmz said:


> dwagoner, so you are suggesting that I set aside the spring I bought at the first part of this thread (part# 9584K67) for the spring you suggested (part# 9588K73)? THe suggestions initially I percieved was that I would only have to compress the longer spring approximately .4 inches to achive 300lbs. so I wouldn't have to tighten down too much. Did I misunderstand that measure?!!!


YES the spring only gets compressed .4 BUT to get to that your eyebolt on end of your jig will need to tighten down the nut an easy 2" and more to get just a 65" string up to poundage, SO when you get to long 90" strings your gonna have to tighten nut down like 3" to get it up to poundage. THis accomodates the stretch in the string material.


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## twistedfreak (Sep 9, 2007)

Can I get any picks to see how you guts are doing this to do it to mine I'm using poor turn style clamps to get mine and I know it's not enough or where I can buy one of these stretchers at 


Sent from my iPhone


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## lc12 (Jul 30, 2009)

Per Automan26's suggestion I bought a valve spring for a 350 Chevy short block.
I put a scale on it and 1/4" compression got me 100 lbs of tension.
I am assuming that 3/4" will get me close to 300 lbs.


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## Nitroboy (Jan 15, 2006)

lc12 said:


> Per Automan26's suggestion I bought a valve spring for a 350 Chevy short block.
> I put a scale on it and 1/4" compression got me 100 lbs of tension.
> I am assuming that 3/4" will get me close to 300 lbs.


No not necessarily, 100#@.25" might end up at 300#@.5" compression just depends on the rate of the spring


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## Dewboy (Apr 19, 2005)

Jig-spring-ttt


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## munch (Mar 27, 2005)

I make and sell string jigs and use a die spring that gives 300lbs at a 30 present deflection. Now when I sell a jig it comes with a spring and spacer as well as a thrust washer to add twist in the string


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