David PetersenMemberJanuary 30, 2010 at 9:04 pmPost count: 2749
Having recently built a dozen footed-shaft woodies that provide only a woeful 12+ percent FoC with 190-grain heads, I turned next to considering the use of tungsten rod for internal footing. If you too are considering going this route, I hope my findings may help you to reach your own wise decision. This discussion focuses on cost vs. FoC gains.
At my local welding supply shop, a 7″ length of 1/8″ diameter pure tungsten rod is $4.50 with tax and weighs 408 grains. To determine how much FoC I would gain with various lengths of rod, I cut rods into thirds and halves, then used a tiny bit of cellophane tape to attach the rod section to the outside of the arrow in the same location it would be if inserted in a drilled hole. The third-length rod raised FoC 6%, to 18+. The half-length rod bumped it up to almost 20%. For now I’m holding it to a half rod, or 3.5″, as anything longer will cause increased problems with keeping the drilled hole dead center and straight in the shaft, and because the added length moves toward the shaft’s center it will have less effect on balance as it gets longer. Certainly, the column of wood that is removed from the core of the shaft via drilling will have some weight, but negligible for these calculations I’m sure, certain well less than 1% FoC difference, so for now I’m ignoring that.
So, the cost of the tungsten alone, when bought retail at this price, is $2.25 per arrow, in exchange for 8% increase in FoC.
A drilling/footing jig from 3Rivers is about $38 with standard shipping ($29.95 plus shipping). You may want to amortize that investment across the number of wire-footed arrows you think you might ultimately build. For an easy starting point for this discussion, 3 dozen arrows would amortize to a bit over a buck each. So let’s say a total of $3.30 each for rod and jig for the first three dozen arrows.
Is it worth it? That’s up to you. An advantage of tungsten aside from its amazing weight is that it’s quite hard and should provide a net gain in shaft strength behind the head, the weakest point on a woody, assuming you get a nice tight fit in the drilled hole. If in fact this saves even a couple of arrows per dozen from breaking, that’s a fairly good decrease in overall cost.
Anyhow, I’m having fun with this so I went ahead and ordered a drilling jig, though the clever among you should be able to figure a way to make one for little or nothing. Now, if only some of the two-blade broadhead makers who are promising heavier glue-ons, in the 220+ category, ever come through, an honest and admirable EFoC of 25% or so should be attainable by woody shooters. And if you can find a more economical source of tungsten rod, that could make a huge difference … and please share with me!
Hope that helps you decide, dave
David PetersenMemberMemberJanuary 31, 2010 at 4:02 pmPost count: 2749
Clay, I’ll let you know about spine change when I get that far with the project. It seems logical that 3.5″ of hard metal rod up front would in itself add some to the spine … or possibly transfer the flexibility back toward mid-shaft and amplify it. I’d be surprised if Dr. Ed doesn’t have a take on this. Also, I am using laminated hex-shafts of pine and footings, which may make my spine results different from a standard PO cedar. We’ll see as soon as my drilling jig arrives. dave
desertdude49February 1, 2010 at 4:17 amPost count: 48
First off, thank you for taking the time and effort on this project. I pm’ed Kye at Great Basin Footed shaft with a few questions.
1. What is the lightest wood shaft material he can get in my spine (85-90).
2. What is the heaviest footing wood he has.
My thought is if he can find or has some lighter cedar than I’m using (mine are around 450gr).Maybe I can get a few more points of FOC by taking it from the shaft and moving to the point area.
I know that every little thing we do helps. I have my first ever Elk hunt this year and I have this deep down burn to use wood arrows. My goal is to get my FOC ove 20%. This is going to be fun, please let me know how you come out with the metal rod….
David PetersenMemberMemberFebruary 1, 2010 at 4:06 pmPost count: 2749
Mark said: “This is going to be fun.”
Bingo!!! It IS fun, which always leaves me shaking my head when folks comment “If you’ve got a system that works, why add stress and trouble your pretty little head with all this EFoC and Ashby stuff?” Of course, because “works” is a sloppy term that generally implies “all else being equal and luck on our side,” which in hunting it rarely is. If we enjoy building arrows, tuning and maybe building bows, practicing … why wouldn’t we enjoy this expanded opportunity to tinker with our gear toward better efficiency when we can’t be out hunting? Man, I haven’t had so much fun with archery in years, experimenting with all sorts of shaft materials, broadheads, purposely taking angled shots at hard targets (usually a big tree) … everything I can think of to test Doc Ed’s findings and demonstrate their worth to myself. It’s the ethical thing to do (decreases wound loss). It’s the self-serving thing to do (increases game recovered and thus success). It’s the FUN thing to do! 8) dave
tom-wisconsinFebruary 6, 2010 at 5:28 amPost count: 239
Dave I heartily agree with you that it is good to be as ethical as we can be. I really enjoy how we can use physics and the scientific method in archery and bowhunting. Hopefully teachers can use these ideas to teach young hunters that science is worth studying.
David PetersenMemberMemberFebruary 9, 2010 at 9:26 pmPost count: 2749
Ed, yes it can be cut with a hacksaw, easily. It’s so hard, it’s brittle. Put a stick in a vice marked where to cut, take a few strokes on it with a sharp hacksaw until it’s clearly notched, then grab the protruding end with pliers and it will snap right off.
For a brief update: I’ve now completed two arrows with tungsten inserts, both having started at about 460 grains, lodgepole pine hexshafts with hardwood footings. With 190 grain points these arrows had something like 13% FOC. With 3.5″ tungsten FOC went to just over 20% and total arrow weight a whopping 835 grains. Spine was unaffected and it still gives perfect arrow flight, though it does have the excessive trajectory you’d expect at that weight from a 55# bow.
The second shaft I used just 1″ of tungsten and got 18.65% FOC with a total weight of 748. Perfect arrow flight again and trajectory was acceptable at 20 yards but still more than I need (looking for 650-700).
To date, thus, I consider this a failed experiment given the cost of the drilling jig, $30, which has yet to provid a perfectly centered hole, the cost of the tungsten, and all the work. It also complicates tapering the shaft for a head.
If a guy still wanted to go this route — which should provide a far stronger shaft end than Woody Weights — he will need to start with a really light shaft. Since I have some tunsten left and bought the jig, I’ll next try it with po cedar.
Yes, you can buy it in different diameters, and in blends such as t-moly, t-copper that may be cheaper but not so heavy. dave
Ed ZacharyFebruary 10, 2010 at 1:35 amPost count: 58
Dave, a failed experiment? 😮
I thinks you’re being hard on yourself.
Maybe a cost-prohibitive arrow building foray?
I’ve used steel rod @ $1.89/3 feet, not near the density
but it still adds front weight. I have some high spined Sitka spruce I’ll experiment with; the more I use Sitka, the better I like it.
Hey thanks for sharing your discoveries, trials and tribulations. Arrow building leads to a pleasant madness and that’s fine by me 😀
Ed AshbyMemberFebruary 10, 2010 at 4:50 amPost count: 816
Dave, there’s no such thing as a failed experiment. ➡ From each we learn something; each expands our knowledge base. 💡 I’m following your weighted wood shaft experiments with great interest! 😮 You’ve already shown that you can get into the EFOC range :shock:; perhaps with a bit too much overall arrow weight for your needs, but it’s useful information for folks shooting higher draw weight bows! 😀
Mark TurtonFebruary 10, 2010 at 5:02 pmPost count: 759
You may find this useful, horseshoe studs have a tungsten carbide core the 4 mm. diameter ones weigh either 25 or 28 grains, they are also really cheap. Ive got about 50 here free to a good home if anyone wants them, alternatively lead shot BB size would probably do.
PS. Steve Snr used tungsten putty and had some good results.
David PetersenMemberMemberFebruary 10, 2010 at 11:57 pmPost count: 2749
Mark — here I expose my cowbow ignorance: I know what a horseshoe nail is, and I’ve heard about the Tennessee Stud. But what’s a horseshoe stud? If it’s a nail, do you cut the head off before inserting? Anyhow, please see my PM.
Indeed, no experiment is a failure … unless it involves your life or someone else’s, of course, but we won’t go there. Again, the trick with tungsten internal footings, aside from the cost, is to start with a light shaft so that the FoC will be higher and overall weight lower (but no less than 650 of course). I’ll get to the po cedar trail soon. I haven’t yet tried the angled tree shots with the tungsten inserts — my standard head-strength test — but will soon — my own snow depth is 5′ but I try to keep at least a short lane to the target tree shoveled clean. Anyone want to buy a Colorado cabin cheap? Gotta be strong and young and single or a couple only, with strong snowshoe legs and snowshovel arms. :wink::) I agree with the “logically self-evident” idea that a strong metal internal insert far enough into the front end of a shaft should strengthen it. Doc — I don’t recall you addressing this. Your thoughts? dave
Clay HayesMemberFebruary 11, 2010 at 12:40 amPost count: 418
Dave, I’m supprised adding that much weight up frond didn’t cause a noticable difference in point of impact due to a decrease in dynamic spine. I’ll have to revisit my tinkering.
A thought for the next round: you may want to taper the end of your insert so that it’s not an abrupt transition from insert/wood to all wood. I think that would slightly strengthen what I think is going to be the weak link (where the insert ends).
Are you glueing the inserts in?
Ed AshbyMemberFebruary 11, 2010 at 4:19 amPost count: 816
Dave, I didn’t address it because I haven’t tried it! I’m trying to learn what happens from your experiments! Wood doesn’t behave like the synthetics, because of it’s cellular structure. The rod should definitely strengthen the section of shaft it’s in, and that could be a big plus. The most common fracture on wood shafts (on hard, real tissue impacts) is just where the taper starts fading into the head’s ferrule. Will the rod create a new weak spot just back of where it ends? Don’t know, but the wood will have a better chance at NOT showing this weakness (where an Internal Footing ABRUPTLY ends) than the synthetics do.
Mark TurtonFebruary 11, 2010 at 10:11 amPost count: 759
Horse shoe studs screw into the base of the horseshoe to allow them to dig in on very soft ground, many of these have tungsten carbide cores that increase their life. I’ll do my best to post a picture latter.
My wife says I’m not to talk to people about tungsten carbide, she says grey metal is not interesting, what do girls know.
David PetersenMemberMemberFebruary 11, 2010 at 3:38 pmPost count: 2749
Clay — sharpening is a good idea! But I don’t have a grinder and that stuff is hard. I’ll give it a try, though, thanks. Yes, I use Duco. And hey pm me somtime about your spring research experiments. Maybe I can make it up this year. dave
HiramFebruary 12, 2010 at 9:07 amPost count: 484
A cold rolled steel rod mandrel turned to the taper and outside diameter of the appropriate thin wall Brass tubing. Quick brazed to the back of the head taper. Course once the Mandrel was turned on the Lathe, the Mandrel would need to be stabilized in the Oven. A short length of Brass (inch or so) would strengthen the shaft (footing) and the brass would braze without loosening up the braze in the Head construction. Good hand with the torch, and properly fluxed rod along with a prepped and cleaned rear taper skirt of the head. Brass would also add some weight and blend with the shaft. The rear of the tubing shank could be beveled to blend. I think also that I just gave away the idea for the heavy head construction. The taper just does not provide much strength by nature of the length. The main function of the Taper is primarily to achieve alignment. As far as the alignment versus the rearward tubing area alignment to the variables of achieving the spin test. Simple gentle spinning of the shaft in a Drill motor coupled with a little sandpaper would relieve the forward to back area of the shaft for proper fit of the hood. Ideally, the entire head constructed in such a way would meet the standards a little better. Just an Idea Dave!:)
One thing I have thought about which I forgot to mention. I think the angle of arrow strike has much to do with the current taper system (WEAKNESS) more so than the the arrow strength at the breaking point. Linear hits are much less likely to break the head or point off when the arrow hits solidly frontal. The impact energy runs the length of the arrow grain popping off the nock sometimes. Since the grain runs one way the integrity of the wood strength is directional. That is why the tapers breaks off of woodies with more frequency than Carbons. Course we all know what happens to Aluminum LOL.
David PetersenMemberMemberFebruary 12, 2010 at 4:59 pmPost count: 2749
Thanks, Hiram. Regarding your first idea/paragraph … brother you are WAY over my head with that. It would take carefully labeled drawings to soak into my low-tech skull. 😕 But I’ll bet it’s a great idea even if I can’t grok it!
Regarding point taper and shaft weakness: Due to the necessity for a streamlined ferrule, I don’t see how we can escape point taper for broadheads. But for target points it should be easy to test. Just slip a blunt or untapered shaft into one of the long-bodied heavier target points and do some angles shots into a hard surface to compare the blunt shafts with tapered shafts? 💡 dave
HiramFebruary 13, 2010 at 6:04 amPost count: 484
Sorry David. I was typeing and having to listen to my oldest daughter during one of her no-stop “Lonely Rants” LOL. I think what I was trying to say was that a Longer, less angle taper on the front of the shaft, coupled with a new Broadhead design to accomplish this is what is needed. The longer taper would allow for the strengthening of the shaft in the forward area say, the first two inchs or so. The longer adhesion area coupled with a lesser degree would also accomplish strength and provide the taper for alignment. So, a Broadhead with a long taper length, along with lesser angle also provides the extra material to add weight for the FOC increase with-out any add ons. Can you see it in your minds eye Dave? Bet all the way to 300 grains easily obtainable. So now all we have to do is prompt someone to make it! LOL. Another benefit would be the longer cutting surface tapered to a 1 inch rear width. Man! Like throwing a Gerber Bootknife on a wood shaft.
Mark TurtonFebruary 13, 2010 at 11:32 amPost count: 759
I can see the reasoning in both arguments and experiments but can’t help thinking that heavier broadheads may be a simpler answer if you could persuade a manufacturer to keep a proven design and just use thicker material and include a longer socket on the broadhead to accommodate some ballast this would allow for tuning.
Just my observations, Mark.
David PetersenMemberMemberFebruary 13, 2010 at 3:55 pmPost count: 2749
Hiram, yep I see it now, thanks. And Mark’s idea sounds solid too. Toward that end, that is what STOS is supposedly doing with it forever-forthcoming new heads, in part: in order to get the weight up and still keep a long/then streamlined (high MA) design, they’re going to a thicker head, which of course increases head strength as well. Other manufacturers are also talking about this. It would seem logical that adding, say, an inch or two of extended ferule that slips over the shaft like a tube — aka the old English bodkin design — would strengthen the shaft at it’s weakest point.But I’m no engineer and it might just transfer the breakage to the back of the sock. Certainly another fun experiment worth playing with … but first the head. dave
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