skidmarks on my arrows

[bowberry]

I built some new cedar arrows this week.

they are flying nicely. I'm very happy with them.

the arrows are white. my strike plate is brown leather.

All my arrows have a brown skid mark starting about 3-4" from the nock to about 7-8" from the nock.

I'm shooting a 50# selfwood long bow (not very center shot at all)

My question: If the tail end of the arrow is rubbing the plate on the way by, is that too stiff or too weak or what ?

Thanks,

Scott

[Tejasmick]

Scott,

Since the shafts are initially striking 7-8 inches from the back, I am going to go with too stiff.  No way they are too weak and going through a cycle before clearing the shelf.  

The less center cut the bow the lower the spine is needed to clear the shelf.  What deflection of arrow are you using?

[bowberry]

.515 deflection. I left my arrows kinda long. around 31". I could go with a heavier tip.

would brace height affect rubbing?

[Tejasmick]

What weight point are you using?

[Nativestranger]

Contact near the nock end usually means too weak. Try raise the brace height and cut down the arrow. One thing I must add is Stu Miller spine calculator is not accurate at all when dealing with self bows and other bows with no cut in shelf. Tends to over compensate for the center cut measurement and suggest too weak a spine. I have bareshafted arrows perfectly straight that the spine calculator says is twice the dynamic spine that the bow needs.

[wingnut]

With selfbows I have found that 15 pounds under the posted weight is a good measure. So if you know the actual weight at your draw you should be able to figure it out.

.515 sounds about right but it's easy to experiment with heavier points to make sure.

Mike

[bowberry]

thanks to all. you've given me much to think about and experiment with.

Scott

[PEARL DRUMS]

I shoot the same spine in all my self bows as I would a glass long bow. For example. My personal hunting bows this year are 48 & 50#. They both shoot a 29" 50-55 with 125 gr up front like a bullet, drawn to 28". Not arguing with your findings wingnut, but I could never get an arrow 15# under my draw weight to fly, not even close. I do read that same advice often, but never witnessed it work amongst myself and friends. We shoot the same spine we build the bow to.

[two4hooking]

I like white shafts.  Mark near the fletch is usually an indication of too stiff.  Mark near the point end is usually weak.

[bowberry]

pearl drums: I have found the same thing, but than, this is only my second shaft purchase.

some of my numbers might be skewed and misleading.

the last time I measured the draw weight, I hooked the scale on and drew back to my anchor. 50#

when I cut my arrows I drew one back to anchor and had my wife mark it. Never did measure it, just cut them all the same.

That may sound silly to some, it just didn't matter at the time.

I guess if I'm gonna ask tech questions I should have good data.

The arrows I bought were 50-55. All tested in that range. the nine that I made up were on the lighter side of the bunch.

Like I said, I'm very happy with thier flight, just curiouse about the skid mark. seeing if I can make good even better.

It had occured to me that maybe they only do it on a bad release, but they all have the same skid mark. Could be that my release is that consistantly bad. LOL

[bowberry]

two for hooking: thats the kind of advice I was hoping to hear.

 thanks again to all,

Scott

[wingnut]

The spine requirement is directly linked to how much you cut the riser for the arrow pass.  We always built them in the Torges hourglass shape with a leather glued on rest.  This made for the need for paradox to get around it.  I've seen selfbows cut to almost center in recent years that would shoot a stiffer arrow.

The 15 pounds is for the wide handle.

Mike

[Slimpikins]

Better than skidmarks in your underwear....              

[PEARL DRUMS]

The sign of a real man! My arrows and my undies have skid marks!  

[two4hooking]

Marks on either one would indicate "something is not quite right".    

[PEARL DRUMS]

If the marks are on the outside of BOTH of those, things really aren't right!

[elk nailer]

you need to wipe em before you shoot em

[bowberry]

elk nailer; I assume your talking about arrows and not underwear. How would wiping them help?

[bowberry]

wing nut; I may be closer to that 15 under than I first thought. My arrows are quite long which gives me less spine than the 50# they are rated.(iv'e never looked at a spine calculator)

Plus If hitting the tail end means "too stiff" than I could go weaker.

So I bet if I shot a 28" arrow I would need to be in the 35#-40# range. just like you said.

By the way, my self bow is old school in design. No shelf, no cut-a-way, 1" wide at the handle. string centered on the handle.

Thanks for the help,

Scott

[Nativestranger]

Bare shafting will reveal what is really going on with those arrows. Fletchings may mask any flight problems. All my non center cut bows prefer at least 15# higher dynamic arrow spine than bow weight. This high speed video show what happens when you shoot an arrow 10# lower spine from a non center cut self bow:
   

and here's the same bow with 50# spine arrow:
   

Another close up look at what happens when you shoot a weak spine arrow. Now think about those skid marks on your arrows.