Author Topic: Initial playing-around with timber arrow EFOC jig... (Read 1044 times)

Benny Nganabbarru · « **on:** August 03, 2009, 04:34:00 AM »

Tim at Braveheart Archery kindly replaced the first jig that I bought with the new and improved version (slightly larger; the first one had tolerances too tight to fit my 23/64 finished Douglas fir shafts). With this second one, I also bought the six inch drill bit. So, I began playing around with the system yesterday.

Benny Nganabbarru · « **Reply #1 on:** August 03, 2009, 04:43:00 AM »

Yesterday, I started by using a pair of 2.5" x 2.8mm nails. I began work on the living room floor, and survived by doing jobs around the house for the rest of the day.

The two nails weighed 96 grains; the weight of the shavings removed in drilling was about 16 grains; so I effectively added 80 grains, plus the epoxy (unknown weight) in five inches. The arrow is a 30" BOP Douglas fir, spined 105/110#, and made by TradGanger Joe Lorenzen (I use these for my Silvertip, but with this front-loading, knowing that my Silvertip is already pushing these arrows to their limits with just the 160 grain point, I was making the front-loaded ones for the Hill Wesley Special). When I finished, the arrow's total weight was 864 grains (up from the usual 775 grains).

Benny Nganabbarru · « **Reply #2 on:** August 03, 2009, 04:48:00 AM »

I went to school for a shoot, and was pretty happy with how the arrow flew. My standard arrow for my Wesley Special weighs 700 grains, so this bigger one was slower. The poor old pet pig is pretty flogged-out, but the honour of the first pass-through went to the big arrow; however, it's no penetration test, as the normal arrow did a few pass-throughs as well, and when I shot them into the target's rump (because it is quite intact), they stuck-in about the same; so, I don't think that 3D targets are suitable for penetration tests - but I bet real animals are.

Benny Nganabbarru · « **Reply #3 on:** August 03, 2009, 04:52:00 AM »

Today, I moved the workshop to the back veranda, which was a smarter choice (I am in the process of negotiations to replace our current old timber kitchen table with a nice new one, and relocating it to the back veranda and setting it up for archery craft and re-loading [actually, it's already set-up for re-loading, but that's another story]). Gabby occasionally got in the way, but eventually got bored and went to sleep.

Benny Nganabbarru · « **Reply #4 on:** August 03, 2009, 04:57:00 AM »

My next-door neighbour gave me a few 3.2mm welding rods to play around with. I banged the flux off with the hammer (note the dust-pan and brush; I do try to behave somewhat). Still aiming to make some EFOC arrows for the Wesley Special out of some arrows made by Joe, I drilled a couple of shafts to take five inches of welding rod.

Benny Nganabbarru · « **Reply #5 on:** August 03, 2009, 04:59:00 AM »

I made an Ace Hex blunt-tipped arrow, and a field point-tipped arrow.

They weighed pretty close to each other.

Benny Nganabbarru · « **Reply #6 on:** August 03, 2009, 05:02:00 AM »

The welding rod was 3.2mm, so five inches of it weighed more than the two 2.8mm nails from yesterday, and fitted the 9/64th drillbit hole better.

Benny Nganabbarru · « **Reply #7 on:** August 03, 2009, 05:07:00 AM »

Then I decided to fetch one of the 105/110# shafts that I'd finished (I've recently taken my first baby steps in making my own arrows) for the Silvertip. Knowing that it most-likely cannot cope with any more than the 160 grains of normal point weight, I decided to drill the rear in order to add some weight back there, to dynamically stiffen the arrow (just like the Goldtip system for their carbons). For this rear-loading, I used 2.5" of welding rod.

Benny Nganabbarru · « **Reply #8 on:** August 03, 2009, 05:10:00 AM »

Previously, I'd make the initial drill using the jig and the standard length bit. Then, I'd remove the jig, put the six inch bit in, and carefully drill away. I did this again, and...

Uh-oh!

I snapped the shaft to have a better look at the wayward hole.

Benny Nganabbarru · « **Reply #9 on:** August 03, 2009, 05:12:00 AM »

After this, I decided to use the jig for as far as I could go with the six inch bit, and only remove it to get the last bit of depth. I did this on another shaft, and added the front and rear weight. I haven't yet fletched it up, so I can't say how it went. Later, for that one...

Benny Nganabbarru · « **Reply #10 on:** August 03, 2009, 05:18:00 AM »

Towards evening, I wandered down to the school, and took a standard blunt and the new blunt (for the Wesley Special). The target was a plastic milk bottle - my all-time favourite target (other than the feral animals).

I did lots of shooting, and was happy with the flight. Of course, the heavier one is slower. Toward the end, I missed the bottle (only just!) and heard a little snapping noise. Upon inspection, I discovered I'd glanced it off a little rock hidden below the lawn, and splintered a large section off along the hole made for the welding rod.

Benny Nganabbarru · « **Reply #11 on:** August 03, 2009, 05:29:00 AM »

So, that's where I'm up to with this EFOC endeavour.

A few thoughts that I have:

1. Five inches is a lot of hole, and a lot of error can take place. Less drilling may produce a stronger arrow, because of a straighter hole. Plus, I feel a little nervous about such a large hole of possibly unknown accuracy.

2. Use the jig for as much guidance as possible.

3. I wish tungsten was more readily available - I've got some coming from Tim, but he says that it might well be the last, as it's really hard to get and to work with. Tungsten seems ideal, as it would pack in the weight in a very small hole. I tried to contact a US rare metals company, but in the inquiry form, I didn't list a company (I don't have one) or a fax number (I don't have one of those, either), and the response I got (which was not an automatically generated one) was that unless I supplied those two, they were unable to deal with me for security reasons - I swear, I'm a good bloke!

4. I noticed that a crown dip seems to add a fair bit of weight to an arrow. How much, anybody? 50 grains? 40 grains? Anyway, it could be an idea to add a little front dip in addition to the welding rod / nail / tungsten.

5. I am really looking forward to Todd Martin being able to put the heavier STOS broadheads on the market.

Cheers,

Ben

SlowBowinMO · « **Reply #12 on:** August 03, 2009, 11:41:00 AM »

Good stuff there Ben!

For those interested, we're looking into some other materials that may be more friendly. The tungsten is the bomb (and bomb proof) but expensive and very hard to work with.

Here's another idea I've not tried yet...I'm going to give the point end of my shafts a little soak in Minwax Wood Hardener after I've drilled them and before I epoxy in the insert. It should add even more strength up front.

Tim

Orion · « **Reply #13 on:** August 03, 2009, 12:34:00 PM »

Good stuff, Ben. Crown dips really don't add that much to the weight, not more than 10 grains or so per dip if memory serves.

Another thing you recognized right off is that there is an upward limit to front loading that's reached farily quickly with high poundage bows. That is, spine high enough to handle the HFOC or EFOC just isn't readily available in standard diameter size softwood (cedar, fir, spruce) shafts.

Don Stokes · « **Reply #14 on:** August 03, 2009, 06:28:00 PM »

Ben, I admire your industriousness, but the prospect of one of those splinters coming off at the shot... that really scares me. I'm a wood man all the way, but I believe I'd stay with the tubular materials for loading up the end of the shaft.

Benny Nganabbarru · « **Reply #15 on:** August 03, 2009, 08:51:00 PM »

Thanks, fellows. Yep, it scared me, too. That's why I think I'll steer away from too much length. It'll be much safer to have just a couple of inches up there, rather than five.

Bill Skinner · « **Reply #16 on:** August 03, 2009, 09:48:00 PM »

If you used a hypodermic needle, like the ones you use for cattle, and squirted it all the way to the bottom, and then put the welding rod in? If you put in enough that excess squirts out, shouldn't it act like a splint and be stronger than the shaft? I am just guessing. Bill

martin guy · « **Reply #17 on:** August 04, 2009, 11:18:00 AM »

Ben,
I roll the rod in epoxy and make sure it squirts out of the arrow, it seems to strengthen the arrow by bonding everything together.
Of course I have only went about 3" deep.

Andy
(Still waiting on tungsten)

Benny Nganabbarru · « **Reply #18 on:** August 04, 2009, 05:16:00 PM »

Yep, I rolled the rod in the epoxy, and made sure it squirted out.

Andy, I looked at tungsten welding electrodes at an online shop (an Aussie one), and from memory they sell 10 3.2mm rods for AU$60. But, when I asked my Dad about it (he's a farmer) he was cautious about thinking that these would be pure tungsten, his reasoning being that they might be rods that are capable of welding tungsten, rather than made of tungsten. He said to check with a welder. What do you reckon? Would these rods be the real deal? Here's the link, if it helps:

http://www.weldsmart.com.au/welding-australia/tungsten-electrodes

Cheers,

Ben

martin guy · « **Reply #19 on:** August 05, 2009, 01:19:00 AM »

Ben,
I sent you a PM.


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Author Topic: Initial playing-around with timber arrow EFOC jig... (Read 1044 times)

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