Chrono results

[upstatenybowyer]

Ty, that's an awesome general description of exactly the information I was hoping to gain. Many thanks brother.

Jim, I figured it isn't the best scale for this. The arrow is from set of 12 I got on the auction site. They came from China. I'm pretty sure they are around 500 grains.

rps3, I didn't realize you could find them for that cheap. I'll be looking for sure. The great thing about this chrony I got is that it has built in LED lights that make it really accurate. I get very consistent readings with slight variations that are probably the result of different draw lengths.

Since I make mostly 50-60# bows, sounds like I should have a set of 500 grain arrows and a set of 600.

Thanks as always for dropping the knowledge on me boys! 

[DC]

 what's a good speed for a 50#bow shooting a 500 grain arrow?

Just a little bit faster than the last 50# bow you made

[Stick Bender]

The problem with chronos is with out a shooting machine or very consistent draw you get errors and no test standards when I post a final  speed I only do it after I leave the bow strung for at least 1 hour and have a total of 300 arrows on the bow and shoot 12 arrows prior to test  that way in my heart of hearts I know the numbers are real also you get faster readings in the winter months if you live where it gets drier in the winter, right now my RH gauge is reading 27 % in my storage room , I have seen as much as a 8 fps drop in speed after breaking in a bow ! But it's the best tool for knowing what your bow will do in field conditions !

[loefflerchuck]

I bought a little digital scale for pretty cheap on ebay a few years ago. It measures in to the 10th of a gram and is still accurate. Then just x 15.43 on my phones calculator
 Once you start to tune arrows to a bow you will probably see the numbers go up. I do consider 10gpp the standard arrow speed test.

[upstatenybowyer]

Cool. Thanks Chuck. 

I bought a grain scale off the auction site today for $4 with free shipping. Hopefully it's not a total POS, but things are tight after Christmas and with both my kids bdays coming up within the next 2 months! 

[loefflerchuck]

That's a better deal than I got. It's easy to check the weight. If you don't have a test weight just use a nickel. They should be pretty much exactly 5g

[joachimM]

There seems to be a confusion between shooting 10 grains of arrow weight per pound of draw weight  (gpp) and shooting a 500 gr arrow.
In TTB4, there's a chapter on bow testing ("turtle bow"). There, all bows are shot with the same 500 gr arrow, no matter the draw weight, no matter the draw length. There the expectation is that a bow is, on average, expected to shoot 100 fps plus its draw weight (pounds) in fps. So a 50# bow should shoot 150 fps to be average, a 60# bow should shoot 160 fps. The former is shooting 10 gpp, the latter 8.3 gpp. Performance is compared by looking at how many fps above the expected average draw weight each bow shoots. A 70# bow shooting the 500 gr arrow 175 fps (5 fps above expected) is doing worse than a 40# bow shooting 150 fps (10 fps above).

However, since the TBB series, we have learned a great deal about bow design, and I have the feeling we have increased the average bow speed. A 50# bow shooting a 500 gr arrow 150 fps is currently less than mediocre.

The other standard is shooting at 10 gpp and 28" draw length. There, every bow is expected to have the same initial arrow speed no matter the draw weight. A 30# bow shooting 300 gr arrows at 165 fps is performing equally well as a 60# bow shooting a 600 gr arrow the same speed.

It's pretty darn difficult to shoot faster than 175 fps at 28" and 10 gpp, even with a composite horn bow. Few are those that have achieved more than 180 fps at 10 gpp and 28" DL.  I haven't.

[upstatenybowyer]

Interesting points joachimM. I do love having this new toy cause it gives me an idea of which bows are most successful. Then I can ponder what it is that worked and try to build off that. 

[Mesophilic]

Something that sometimes helps get you closer to the ballpark with digital kitchen scales is to put a weight on it an then zero it.  So if your scale maxes out at 10 pounds,  put a 5 pound weight on it and then zero it out.  A canned food item can fit the bill. 

On my kitchen scale if I do this I end up getting an additional 2 to 4 grams added on to the weight of heavier objects and 1/2 to 1 grams additional on lighter objects.  Which is more accurate according to my digital reloading scale.

[Selfbowman]

I get about 160-170 fps out of a 50 # bow with a 500gr arrow. But I know there are bowyers out there getting faster readings. On occasion close to 175. That's when I do my job with a good stave. Arvin

[AndrewS]

I have measured most of my bows. The fastest Bow in my collection is a bow from Marc. It is a 62" deflex reflex static recurve (HHB  with ash backing) 48# @ 27". With a 475grains arrow and 27" draw I reached several times 180+ fps. With some other bows I reached  170+ and  175+ with the same  gpp arrowweight and the same draw length. The bows are from Hickory,Osage,Osage backed  with sinew.

But I dont shoot better the faster the  bow is! I think velocity isn`t the key for better shooting.

[Morgan]

When you guys talk of arrow weights in terms of 10 gpp is that for a finished arrow with point or shaft weight? I assume it is for a finished arrow, but wanted to be sure.

[upstatenybowyer]

Good question Morgan. I assumed it's for a finished arrow too. I'm sure someone will set us straight...

[DC]

Finished arrow.

[AndrewS]

Finished arrow.