Author Topic: Compressing Shafts. (Read 20004 times)

agd68 · « **on:** February 25, 2010, 10:01:59 am »

I seen a tool while cruising 3Rivers . It was a arrow shaft compresser. Apparently you run an 11/32 shaft in one end and it comes out a 5/16 on the other. What does this do for a shaft besides making it thinner ?

ken75 · « **Reply #1 on:** February 25, 2010, 10:10:56 am »

it stiffens the arrow increasing spine. if i remember correctly

Cacatch · « **Reply #2 on:** February 25, 2010, 10:13:33 am »

Yes, what Ken said. I would think it might be a reasonable investment. In my opinion, smaller diameter, shafts are better if you can maintain the same weight. This is why carbon shafts are so thin. To let the arrowhead be wide if you want, but to keep the shafts thin and still have some weight to them.

artcher1 · « **Reply #3 on:** February 25, 2010, 03:58:20 pm »

Reducing diameter reduces spine. ART

El Destructo · « **Reply #4 on:** February 26, 2010, 01:56:46 am »

Quote from: artcher1 on February 25, 2010, 03:58:20 pm

Reducing diameter reduces spine. ART

I may be wrong...but I disagree...if you are taking the larger Diameter Shaft...and compressing the Fibers down to a smaller Diameter...hense tightening the Grain...this should increase the Arrows Spine,,,,not decrease it.... like sanding or trimming it to reduce Diameter....JMO

CraigMBeckett · « **Reply #5 on:** February 26, 2010, 07:32:59 am »

El Destructo ,

The bending or buckling of a column is described mathematically as shown in

http://en.wikipedia.org/wiki/Buckling

Dy compressing the column you would make the moment of inertia smaller, see

http://en.wikipedia.org/wiki/Area_moment_of_inertia

Therefore you would reduce the spine.

Craig.

El Destructo · « **Reply #6 on:** February 26, 2010, 08:19:13 am »

I know that when you compress a Copper Wire for a Flaking Tool....It makes the Wire Stiffer...so I would figure that it would have the same effect on Wood....But If Science and Mathematics are against Me.... I stand Corrected.........

Pappy · « **Reply #7 on:** February 26, 2010, 08:54:02 am »

WOW,I should have listened more in school, ,I would compress one and see for my self.
I would have thought it would have stiffened it. Not by reducing it,we all know that would make it lighter but compressing it I would think it would make it stiffer.

i will have to do my own
scientific study on that.

Pappy

George Tsoukalas · « **Reply #8 on:** February 26, 2010, 09:58:49 am »

I do it all the time with a screw driver. I haven't noticed much difference in spine. I do believe it strengthens the shaft. Jawge

jamie · « **Reply #9 on:** February 26, 2010, 10:08:26 am »

you'll lose 5lbs of spine. if you use 45-50's , compress a 50-55 and you'll have what you need. buddy used one a while back. not worth the effort in my opinion. if you are doing this for better penetration use a tapered shaft. they are easy to make . same rule applies to tapered shafts. go 5lbs heavier and after a 12" taper you'll get back down to your desired spine.

CraigMBeckett · « **Reply #10 on:** February 26, 2010, 10:28:51 am »

El Destructo

Quote

I know that when you compress a Copper Wire for a Flaking Tool....It makes the Wire Stiffer...

Absolutely correct but you are nor so much compressing the copper, that is changing its sectional area, as you are work hardening it. It is this work hardening that gives you a stiffer piece of metal. You are increasing the modulus of elasticity E in the equation when you work harden the wire.

Craig.

Greatgoogamooga · « **Reply #11 on:** February 26, 2010, 11:57:32 am »

Here's a though experiment. Take a pice of 30" copper pipe, 1/2" diameter, like those used in plumbing and bend it in your hands. Now keep the same length, but increase the diamter to 6". The larger diameter would be thinner, but would be harder to deflect. It would also be more prone to breakage.

I learned this lesson back in the 80's when I worked at a bicycle shop. That's back when the manufacturers started experimenting with over-sized tubing. Today, all bikes use the larger diameter for greater stiffness at the same, or less weight.

Goog

half eye · « **Reply #12 on:** February 26, 2010, 12:23:19 pm »

Hey triple G,
I'm kinda like Pappy, but I shoot hardwood arrow shafts and usually like the big ole fat kind....but I can make small diameter stiff spined as well.....just change the wood. I really like black ash for my personal arrows (these weigh about the same as spruce but they are a lot tougher)....if I want to go small, but still want spine and weight I use maple or white oak.
Know that isn't really what you asked but like pappy, I should've paid more attention in school too. Changing wood was my solution, and I seem to do everything the hard way

half eye

ken75 · « **Reply #13 on:** February 26, 2010, 04:11:11 pm »

i guess common sense isnt all that common, i was wrong

JW_Halverson · « **Reply #14 on:** February 26, 2010, 05:04:42 pm »

Quote from: Greatgoogamooga on February 26, 2010, 11:57:32 am

I learned this lesson back in the 80's when I worked at a bicycle shop. That's back when the manufacturers started experimenting with over-sized tubing.
Goog

I remember those beer can bikes!

I was just looking at that shaft compressor in their catalog yesterday. I bought two dozen 23/64th tapered cedar shafts last summer for $5 and I cannot get them to shoot straight. I left them full length (32"), put 160 grain field points on them and they still come off the bow hardnock right. The bow is pulling 50# at my normal 26" draw, but I can adjust my stance and pull 27 just as easy for a little more draw weight. I just kinda hoped with 4 inches over the standard 28, heavy points, tapered shafts, and overdrawing slightly I could make use of them. I suppose I will have to buy the tool and post my "product review".

Primitive Archer