String Jig Design

PLEASE HELP TO FUND ARCHERY INTERCHANGE

Rik

Supporter
Supporter
Very true, if your jig turns into a banana its not going to help because the strings will slide past each other, if your jig isnt up to it just chuck a clamp at both ends to hold it onto a solid work bench.
That only works if you have a solid work bench (and clamps!). There have been times in my life when I've had access to neither, but still needed to make strings... Something like a Spigarelli jig (i.e. built like the proverbial brick out house) is ideal.
 
Ahh now I can see that might be a problem.. I'm very lucky and have easy access to both...

If that is the case, I'd go for white oak dimensional lumber, its a fraction more expensive than some other timbers but its nice and strong, quarter sawn would be the best if you can choose..
 

Bertybobby

New member
I used two lengths of the stuff they use for stud partitions. Spacer inbetween, then screwed and glued together. This makes a slot between the two lengths to slide the post holder up and down and allow it to spin when the bolt is loosened off.

3m lengths are about ?3.50 from the builders merchants.

Sent from my Nexus 7 using Tapatalk 4
 

carl7

New member
Well after taking a GOOD look at the stuff in my basement, (a messy job!) I've decided to make a metal string jig of four pole design. Thanks to my dad who left a lot of stock metal, I found lengths of square tubing. He also had some 3/4" brass rod already cut to length with a shallow 1/4" hole in the center with a set screw for securing a rod. Perfect!

Steel_Square_Tube.jpg

BrassRod.jpg

The lathe works as it did 35 years ago, all the tools are there, carbide cutters, three and four jaw chucks, dead ends, center rests, the works.

All I need is to attach the brass rods to the length of square tubing by bolts. On the brass rods, I'll use the lathe to drill a hole in the bottom and tap threads.

My question:
1. What should the minimum distance be between posts? (depends on how long the end serving is)

I had thought of making the square tubing arm long enough for posts at 8-10-12 inches. Do I need more distances to perhaps 14" - 16" ?

Thank you,
Carl
 
My posts are 18 inches apart, but I make strings for my horsebow, to be honest it doesnt really matter so long as its rigid, but a nice wide set give you more working room and versatility.

A word to the wise, make sure the uprights are high enough so that you can easily swing your serving tool around the string without it hitting the jig.
 

Bertybobby

New member
Mine are 18 inches apart and I do recurve strings. The top loop of 2", needs 4" plus 3/4 of an inch, so just under 5" of the 18".

I put my centre serving on with the string on the bow.

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carl7

New member
Thanks guys! that answers my question, and good thing I asked, I hadn't thought that I may need to go out to 18" but I want the capability.
Yes, Kieran, right now, the area on the posts where you wrap the string loops will be 8 inches above the arm. The length of string I can make will depend on the length of the main beam (the unistrut type possibly) but I do have 8' lengths of super heavy (3x3x1/4") plate angle iron.

The great thing about this jig is I can make / modify arm extensions and posts to any length since everything is bolted together. That's why I did not opt for welding.

Today, I'll Scotch pad the metal to get the light surface rust off then cut / drill. When ready, I'll do a phosphoric acid bath the steel arms to neutralize any rust and then prime and paint before attaching the posts.

Carl
 

Bald Eagle

New member
Carl, my "stretching jig" is made from box section steel, heavy duty stuff, one piece slides into the other piece. I've drilled holes through both pieces at intervals so I can push a rod through to lock it off depending on the string length. I've bolted an angle bracket at each end, one has a fixed hook and the other has a hook with a long thread and a bolt. I transfer the string when made and the ends served, to the stretcher, where the twists are put in and then I tighten the bolt until it hits "middle C" !!!! Then I finish serving the ends and centre. A rough guide I use is if the string moves/twists while it's being served, it is not tight enough on the stretcher!
 

carl7

New member
Thanks for the tip Bald Eagle, I didn't think of a stretching jig, I'm going to have to think of a design. Unfortunately the square tubing I have won't fit inside the other.

I do have lots of various pullers for auto bearings and transmission gears, with lot of hooks and metal loop parts, sort of like metal cable rigger's supplies, perhaps I can find something that will work as a stretcher. There's also a few winches of the hand crank type.

When dad died a decade ago, I was advised to "dump or sell all that rubbish" I'm sure glad I have a bit of a stubborn in me, I said no!

Carl
 
Simple stretching jig,

Solid as a rock string jig with two twin upright sections that can freely rotate.

Put the string on one side of the uprights.

Put a tensioner between the other two, whether its a threaded one or a strong bungee cord.

Tensioner pulls in, which pulls the other side of the bars apart, stretching the string.
 

carl7

New member
Simple stretching jig,

Solid as a rock string jig with two twin upright sections that can freely rotate.

Put the string on one side of the uprights.

Put a tensioner between the other two, whether its a threaded one or a strong bungee cord.

Tensioner pulls in, which pulls the other side of the bars apart, stretching the string.
Thanks Kieran, I remember seeing something very similar, but I forgot about it, thanks for the reminder. Yes and you can also increase the leverage depending where the pivot point is, even variable with couple of pivots.

Carl
 
Gloriously simple equation for that, so long as your two pivots are rigid enough haha..

My jig was made primarily as a string jig, stretching is just as easily done with a hook and a weight so.. Personally I just stick it on the bow and put a few dozen down range using nice heavy arrows (larger inertia) to stretch it in before serving. Or even just string it for a few hours, realistically its always going to stretch after arrows, whatever you do.

Still, stretch with fastflight its well, well below 1% so over a 150mm stretching area its around 1mm.

I've, when rushed, made and shot competitions with strings that I threw together minutes before and honestly it made no difference. People get obsessed about things that make fractional difference compared to their own variation shot to shot, no matter how good you are.
 

julle

New member
Here's a simple one I built. includes a stretcher, don't know how much tension I put on, I just do it so it's tight enough so my strands don't twist while serving.

 
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