MYOG Titanium/Carbon Fiber Ice Axe

[Paul Tree]

Added lightening holes.

Including at the end (a) to allow extra flex.

Also eased corner edges at b, just enough to help prevent pop through, and allow a little extra glue to seep in and help to pad.

[Paul Tree]

detail view of end features

[Steven Evans]

The CF Inserts arrived, and I'm picking them up tomorrow. Testing later this week.

Waterjet work is complete and shafts are here (see pic)…it's sarting to come together.

[Denis Hazlewood]

Be still my heart. This is just like Christmas, when I was 6.

Red Leader (#18)

[Steven Evans]

I just finished testing one of the shafts with an insert bonded inside it. The insert was cut to a length of 3 inches. The OD is ground perfectly and just barely slides into the shaft. I put a small amount of epoxy into the shaft and pushed the insert in until it was flush with the shaft rim. It dried overnight and I set it up in my fixture.
I placed the original 40 lbs on the shaft and I continued to load the shaft according to the UIAA specification until I used all my weights to achieve a load of 57lbs. Having no more weights, I went and filled a bottle with 4 liters of water (8.8 lbs) and placed it on the weights – I was sure my axe would now snap…but my fixture broke!…and the shaft is still in one piece. :)
So, now my shaft testing fixture is broken. I still have a fixture for testing a completed axe in the same manner (it won't work without the welded head section), and being so close to finishing the run of axes, I'm going to wait to test a completed one.
The axe having held roughly 60 lbs is quite substantial – have you lifted 60lbs lately?…it's freakin' heavy. I had to keep taking it off the shaft to load it with more weights (1 -2 pounds at a time) and then back on the shaft…I was sweatin' up a storm!

[Denis Hazlewood]

Hot Da-m!

[Derek Goffin]

Great news, shame about the testing fixture.
It looks like you might have one (or 2), just in case, axe(s) ready,just in time, for my Pyrenean trip. To smooth the way how do I send payment? I expect other people will need to know that too. Of course its not the end of the world if its just not in time?

[Derek Goffin]

If I understand you correctly Steve you put in an insert just over twice ferrule length, flush to the end. I was hypothesizing a 1.5 ferrule length insert pushed in 1/3rd ferrule length extra. The inner end of your insert is 3" from the shaft end. In my scenario it would have been about 2.6" so my 55% increase prediction is being tested or slightly greater say 56%. Again as I understand it the shaft has just acheived 50% unbroken.
I guess the 3" insert weighs about 11 gram. I claim the difference between: a shorter insert pushed in further than flush, as compared with a flush 3"/2.6" insert will be no strength loss and 2 grams lighter

[Roger Caffin]

You know, I am not really fussed about the extra 2 grams :-)
I reckon the flush top end is a good idea, but I am hard-pressed to explain why.

Cheers
Roger

[Derek Goffin]

I totally agree, it is a game only, it matters not.

[Derek Goffin]

I think Steve now has a really good shaft.
I thought of an argument why it is even better. Steve had 2 options a wider diameter stronger stiffer shaft or an insert to stiffen and strengthen only round the point of maximum stress.
If he had egineered both and tested them so they both failed at the same load with his static load test. I would still have chosen the stiffening insert.
The real life test is something like self arrest. It has a high dynamic "snatch" factor. The insert will allow more bending in the shaft before failure, than the larger diameter CF tube would. We are in a position like climbing with a dynamic stretchy rope. The stretch absorbs the energy of the fall and reduces the maximum load that the rope has to take. In this case more bend in the shaft before failure reduces the maximum static load and reduces the chances of failure.
This axe is going to be good

[Derek Goffin]

I think engineers would agree with what I said in my last post, give and spring without weakening is a good thing in a dynamic situation.
Apart from the 2 gram irrelevant gain, pushing the insert in a little bit like I suggested, allows flex at both ends of the shaft. If it is good at the long end surely it is good up inside the ferrule too. I am not so sure about that but you will agree the point is more important than 2 grams.

By the way prediction game 2. If Steve puts the shaft as tested into a head and tests to destruction will failure be:
1) somewhere in the head, Steve's analysis showed the weak spot
2) in the shaft transversely at the end of the insert,
3) as prototype 3 in the shaft transversely at the end of the ferrule,
4) longitudinal failure of the CF shaft
5) somewhere else?

My guess is 3

[Steven Evans]

Derek, while I would love to have these ready for you in time for your trip…delivery of the ferrule and spike is actually July 9th. I'd still have to weld, media blast, and assemble. I called the guys today to see if they could speed it up but haven't heard back. What is your exact date of departure?

Payment will be via paypal with most likely $10 shipping to continental US and Canada, but we'll get into that when these puppies are ready to go – I don't want this to turn into a Big Sky fiasco!

[Steven Evans]

Funny you guessed that it would be 2 grams lighter…The 3" Carbon insert weighs 2 grams (actually 1.95) in total. Reason for it being flush to the top of the shaft is that…ummm…it seemed that was the right thing to do?
I could push it down a little further, but it's tough to get in there, perhaps I will on the production run – 1/2" or so.

[Steven Evans]

Derek, this is a good game, and I have no idea what the answer is. Even after loading it up yesterday, it shows no signs of splitting/cracking/ breaking.
The flex is unbelievable on the shaft. With the 57 lbs placed 50 cm fom the end of the ferrule, the shaft was deflecting about 6-8 inches. The shaft was held rigid and horizontal – the shaft was flexing so much that I had to put a piece of duct tape around the shaft to keep the weight from sliding off!
The downfall…I have a limited number of inserts. Enough to fill the orders for the axes I have promised, but then I'm afraid that's it. There may be a few left over, but we'll have to wait and see if anyone backs out. Purchasing window is officialy closed. :(

[Steven Evans]

OK, my apolgies…the carbon insert weighs 4.5 grams. I reversed the numbers while dividing. :o

32 grams = 21 inch shaft

32/21 = 1.52*3 = 4.57 grams CORRECT

21/32 = 0.656*3 = 1.96 grams OOPS!

[Derek Goffin]

Thanks for that Steve no chance of it happening before we go then. no problem. I live in UK so more postage. We thought a delivery of 3 to me, for us and Rog Tallbloke

[Derek Goffin]

Steve "I could push it down a little further, but it's tough to get in there, perhaps I will on the production run – 1/2" or so."

Yes that is what I think

[Roger Caffin]

> I could push it down a little further, but it's tough to get in there,
At 3" length in a 1.5" ferrule I don't think making it protrude further will add any benefit. Me, I would prefer it flush at the top. My 2c.

Cheers

[Derek Goffin]

At 3" length in a 1.5" ferrule I don't think making it protrude further will add any benefit.

I agree the main improvement is already done, this is minor.

[Paul Tree]

"I think engineers would agree with what I said in my last post, give and spring without weakening is a good thing in a dynamic situation." – Derek

If breaking at the ferrule bottom edge, it is in effect acting like a sharp edged and inflexible anvil. Is there a way to give the ferrule end some flexibility by thinning? Or would the titanium not be springy enough and just deform? Titanium has a low modulus of elasticity according to this link:
http://www.engineeringtoolbox.com/young-modulus-d_773.html
:(

In any case, easing the sharp edge on the inside of the ferrule would make it less penetrating of the shaft. Maybe even go to a small diameter round-over. Then use an epoxy formulation that is, at the hardest, intermediate in hardness between that of the shaft and that of the ferrule, in order to extend the moment of impact and effectively lessen impact.

Weight considerations might rule it out in real life, but for a thought experiment visualize a shaft that is fixed into a thick coat of resilient glue (let's exaggerate thickness and resilience: 1/8" of ShoeGoo) and how that would perform. The glue would absorb some of the pressure and be denser in areas that were compressed, with that pressure tapering off quickly away from the ferrule end. The thinner the glue layer, the less chance it has to spread load, so a thin smear of glue would not make much of a difference.

Let's tweak the experiment: glue to be 1/16" of the gray epoxy used to adhere highway reflectors, and put a 5 degree bevel inside the ferrule that extends about 1/2" inside. Now there is a consistent 1/16" between ferrule and shaft, and at ferrule end, an additional space for glue that provides extra padding and dampening where most needed.

The strain is still focused on the inner ferrule contact edge, now located 1/2" inside the ferrule because of the bevel. Now extend the bevel to just past the half way point of the ferrule, and heavily ease the inside bevel edge with 60-grit sandpaper. The strain can now spread from a single line on the shaft to a wider surface, with the glue moderating.

This is only useful on the front and back of the ferrule, so a slightly oval ferrule with a round shaft would allow the benefits above with 1. less glue weight around the sides and 2. not needing as great of a fixture to set the shaft centrally in the glue.

Ok can't resist Paint::

[Nia Schmald]

Hi Steve,

Any update on completing testing and building these beauties?

[Roger Caffin]

> easing the sharp edge on the inside of the ferrule would make it less penetrating of the shaft. Maybe even go to a small diameter round-over.
I think this has already been included in the design.

[Steven Evans]

Nia,
Just waiting for parts at this point. I sent purchase orders last week and had an original delivery date for July 9th…I have now been told that it is not possible to meet that deadline as material delivery has been delayed – I'm waiting or an updated date. The process is becoming painfully slow, but I'm sure it will all be worth it :)
I was originally hoping that I could start sending them out by mid july…unfortunatley it looks as though it will be closer to begininng of August.

Paul,
Those are legitimate ideas, and I do agree that there are better ways to improve the strength then what was done – (A tapered I.D. shaft would solve all problems). Unfortunatley, I have to be realistic with what I can do and still offer this at a reasonable price. At this point, I think we have reached a very stable product that will meet the users expectations. I personally think it is overdesigned for what I will use it for…might not be that for others though.

[Paul Tree]

just thinking for next version you know.. seriously they sound great, and the snow flies in 3 months!

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