Forum Replies Created
- Ed AshbyMemberFebruary 16, 2018 at 7:01 pmPost count: 816
First, let me apologize for not being able to reply sooner but I’ve been away getting huperbaric chamber treatments for the last seven weeks and just occasionally get to come home for a Friday night and Saturday, then it’s back for more treatemnts. I’ve got several more weeks of treatments to go. There’s no internet connection available where I have to stay for the treatments so can’t really keep up with things. Now, on to your question.
The TPI was developed in the mid 1990’s and was derived for the study’s data to that date. That testing was centered around arrows on ‘normal’ to ‘heavy’ weights and having normal to high of FOC. For these arrow setups the TPI works very well for predicting the average outcome penetration in tissues. As later testing progressed into both light/fast arrow setups and into the effects of higher amounts of FOC I found that the TPI did not accurately predict the average outcome penetration. Applying the TPI formula to light, fast arrow setups greatly overestimates the resultant tissue penetration. When applied to Extreme and Ultra-Extreme FOC arrows the TPI greatly underestimates the average outcome penetration in tissues.
Hope that helps answer your question. Hopefully, some day, it will be possible to expand the TPI formula to cover these factors that were overlooked the first time, but much more data, especially with EFOC and UEFOC, needs to be accumulated.
- Ed AshbyMemberAugust 25, 2017 at 4:12 pmPost count: 816
Absolutely, Smiley, and not just broadheads. I’m particularly excited about many of the new, light and stiff, small diameter shafts and some of the inserts/outserts that folks are experimented with. It’s relatively easy to hit 30+ percent FOC with some of these newer components. I’m also looking forward to working with a university with access to an ultra high speed camera.
- Ed AshbyMemberAugust 22, 2017 at 7:23 pmPost count: 816
Scout, I don’t know yet whether new reports from hunters will be accepted into the new data or not. Per my request, they WILL NOT be using my data and building on it but, rather, they will generate new data to see if they get the same results as I. They will also pick up testing from the point where I had to stop and carry it forward. They will be using the same 118 data points from each shot as I used, so data comparison can be direct. Also, just as with the original studies, there will be numerous ‘focal test’ into specific things; such as I did with types of edge finish, broadhead skip angle, etcetera. The collective group is still formulating other test plans but nothing I can pass on at this time.
- Ed AshbyMemberMay 6, 2017 at 8:53 amPost count: 816
Not being among those ‘sharpening challenged’ I’ve never had any trouble getting either single or double bevel edges truly sharp. That said, as far as final cutting efficiency is concerned, when equally sharp, a single bevel head cuts with greater efficiency than a double bevel head sharpened at the same angle. That occurs because the single bevel head’s edge is thinner; 1/2 the thickness of the double bevel’s edge. This gives a higher mechanical advantage to the single-bevel’s edge, allowing it to do ‘more work’ with any applied force. That means it requires less pressure between the vessel and the edge for the vessel to be cut; ergo there is greater cut efficiency, more vessels are cut and the cuts are deeper, thus bleeding is of a greater volume. Additionally, the thinner edge leaves a cleaner cut, with fewer of the cells lining the vessels being disturbed. This inhibits the production of prothrombin, slowing the blood’s clotting time, contributing to a greater total loss of blood.
The thinner edge of the single bevel head does require that one use a head with a high quality of steel with a hardness of R52 or greater. The simplest test of whether the head has steel appropriate for a single bevel broadhead is that it should still be shaving sharp after exiting the animal, regardless of the tissue(s) hit.
Col Mike has the best advice for anyone having difficulty sharpening a single bevel broadhead – call Joe or Ron and they will talk you through the learning process. The final result is worth the effort.
- Ed AshbyMemberDecember 15, 2016 at 1:25 amPost count: 816
The initial testing of EFOC/UEFOC effect on the Heavy Bone Threshold showed no effect on the bone-breaching rate. However, when compared to matched-set arrows of normal/high FOC they DID show a very marked increase it the total outcome penetration in all instances where the arrow did breach the bone (with arrow sets both above and below 650 grains total mass). They DID NOT show any increase in the bone-breaching rate in all matched-set testing of the Heavy Bone Threshold with arrows having below-threshold mass (below 650 grains total weight). Above threshold weight all sets tested showed a 100% bone-breaching rate, regardless of the degree of FOC.
I must note that this testing was done during the last year I was able to do testing. Though the data is limited the frequency and magnitude of the increase in post-breaching penetration demonstrated was easily sufficient to say that having EFOC/UEFOC is a great benefit once the bone is breached.
There are a number of folks who are hunting with arrows in the range of 31% to 32% FOC, and a few using slightly higher FOC. That, of course, does not take into account those natives in Papua New Guinea who are using arrows all the way up to well over 40% FOC.
- Ed AshbyMemberJuly 16, 2016 at 3:52 pmPost count: 816
Ausjim has the right idea. More game will be alerted by reflection off the watch’s crystal than by sound the watch makes. That’s especially true for the stalking hunter but can happen any time your hand moves. When we use to hunt the open mountains and tundra and split up to hunt opposite sides of the valley one of the easiest ways to locate the other others across the valley was to watch for that flash of light off their watch’s face (or any other reflective surface that wasn’t covered). I always used either a watch band with a cover or used a pocket watch.
- Ed AshbyMemberJuly 7, 2016 at 11:29 amPost count: 816
If the dynamic spine is truly ‘stiff’ then, yes, building the side plate out will make it worse. If, however, you are getting a false ‘stiff spine’ because of the shaft impacting with the side plate building the side plate out will improve the dynamic spine. Temporarily building the side plate out with tape is a fast way to fine out what’s really going on.
- Ed AshbyMemberJune 22, 2017 at 8:35 pmPost count: 816
Col Mike wrote: “This will take any north American game.”
Don’t sell your arrow setup short Col Mike. While I believe one should always use all the bow one can handle, if 52# draw and that arrow setup was what I had to use I’d feel comfortable up through Cape and Asian buffalo. Elephant, hippo and giraffe? Think I’d want a bit more bow and a bit more arrow.
- Ed AshbyMemberFebruary 18, 2017 at 5:16 pmPost count: 816
R2, no disrespect intended but it’s clear you did not read any of the articles, all of which were produced by the recognized scientific community; that community folks always tell me is the only ‘scientific’ research that they will recognize. The questions you asked are all answered there. There you will also find explained that what appear to be a ‘double bevel’ stone points really are not, and why. The technique is found on stone points world-wide, and substantially pre-dates the American Indians.
Truly, there is nothing new about single-bevel points. We ‘moderns’ just forgot what our ‘primative’ ansestors knew long. long ago.
- Ed AshbyMemberFebruary 18, 2017 at 1:11 pmPost count: 816
What we think we see and what is actually there are often different. You should find the following research papers of interest.
http://www.academia.edu/14516831/How_atlatl_darts_behave_beveled_points_and_the_relevance_of_controlled_experiments (once you go to this link you’ll have to request permission to access the document but it’s well worth the trouble)