May 13, 2008 at 9:38 pm #1228955
@ryanLocale: Rocky Mountains
Companion forum thread to:May 13, 2008 at 11:02 pm #1433175
Rick DreherBPL Member
@halfturboLocale: Northernish California
Guys, this is an incredibly impressive project. Kudos all around!May 14, 2008 at 7:53 am #1433201
Firstly well done Steve and everyone a truly impressive project.
I confirm my preorder of 2 axes especially as you can hold the price!
when you field tested the 3rd prototype did you notice improved adze and pick swing and penetration? Do you think it close to optimal for the weight? At this weight the axe will never be good at cutting steps would it do this at all?
The finished head looks suitable for experimentally strapping 2 aluminium or plastic cylinders, one each side of the pick. They would be to be filled with water or ice to increase swing weight when needed. Roger suggested this. Do you think, having used the axe, that the experiment is worth it?
One of my criteria for success was that the axe was at least as strong as the Helix potty trowel. Is it possible either with software or hardwear to give some comparative figures for UIAA test 3 and the spike cantilever test for an axe using similar materials and dimensions to the potty trowel?
As both of these tests of prototype 3 failed on the carbon fibre shaft maybe the potty trowel is stronger?
At some point in the online discussion it was mooted that a carbon fibre insert or lightweight core might be inserted to stiffen the shaft at stress points. As you say you can "now reinforce inside the tube if needed". It occurs to me that maybe the above results could be improved in this way for little extra weight. If I remember correctly the shaft is relatively very light so short carbon fibre inserts ought to be very light.
Looking at your costings the thing that jumps out at me, as maybe saving cost, is the machining of the spike. The spike is not the crux of the design problems, yet machining it out of solid titanium rod costs 22.7% of the total cost. I wonder whether a thin titanium tube is available which would be cut at an angle and glued to the outside of the shaft with very little other machining. It would appear to be cheaper to adjust the diameter of the CF shaft to fit whatever titanium tube is available than to machine the spike to fit the CF. Titanium outside the carbon fibre was stronger at the head and may also be at the spike. If the spike is strong and the shaft breaks in prototype 3 a lighter simpler spike outside and a stiffening core inside the shaft might be lighter, stronger and cheaper. I suppose an increase in diameter at the spike is not ideal, as the spike is more likely to get stuck in ice and rocks, but I would live with that if the other effects were good.
The other thing you can do to reduce costs is increase batch size and with results like these you may be able to! What do you think the marginal cost of the 26th axe is, without design changes?May 14, 2008 at 8:48 am #1433217
.May 14, 2008 at 10:19 am #1433230
@rmkrauseLocale: Pacific Northwest
That is so awesome. Engineers rule.
Local university mechanical engineering department might be a way to access a formal metrology lab for testing. There are commercial labs that will do the testing but no idea what they would charge.May 14, 2008 at 4:29 pm #1433288
Great work Steve! You mention that you had two different types of shafts to test, but I don't see anything about this later in the article. Did one turn out to be stronger than the other?
While I agree that the UIAA specs are not necessary for a walking axe, what do you think it would take to get this axe up to type B? Can it be done reasonably with a carbon fiber shaft? How much weight would this add? It seams like the head is already up to the job with the shaft as the weak link, but are there other tests that you didn't run that you think the head would fail on?
Finally the most important question, when can we get one?
Thanks for the great work. It almost makes me wish I had gone for ME in college instead of that silly computer stuff. You've got much cooler toys.May 14, 2008 at 7:35 pm #1433332
> While I agree that the UIAA specs are not necessary for a walking axe, what do you think it would take to get this axe up to type B? Can it be done reasonably with a carbon fiber shaft? How much weight would this add?
I imagine Steve can give you more detailed answers, but a thicker wall on the CF tube would go a long way. It might double the (very low) weight of the tube.
cheersMay 14, 2008 at 7:57 pm #1433338
Thanks for the positive comments!
Now, to answer a few questions.
Excellent questions – I found the axe to swing better then the old version. You can see this in the profile of the head and the angle of the adze, but I have limited use of each one, so I can't make a solid comparison quite yet. Like the Helix, all the weight is in the head, which will help somewhat with penetrating harder surfaces, but it will have limitations. The titanium is stronger then the steel heads out there, so you can really give it a heavy beating without worrying. As for strapping bottles to the side of the head, it may be possible – but I'll leave that option for you to explore. :)
I haven't used, held, or even seen(except on the net) the Helix, so I can't comment on it's strength. If someone has one they don't want ;), send it to me and I'll test it with the same tests. The problem with just calculating it's strength is that carbon fiber is a finicky material. Everyone makes it differently, with the various wraps and fibers, so it's tough to compare with just geometry.
The carbon insert is a good idea and would most likely work, but it would be smarter to just go up on the outer diameter of the shaft. Increasing wall thickness (which is really what we would be doing), while keeping the outer diameter the same, is bad bang for the buck. Of course, then we add weight…at some point we will be darn close to the 8 oz mark – and Camp has an 8oz B-rated axe. :(
Regarding cost savings, no one was more surprised then I! Not only did the majority of shops come back with 'no quotes', the ones that did come back were astronomically high. Titanium is very hard to machine, especially in a high production enviroment. The chips can actually catch fire (I have first hand experience with this) so lots of places won't go near the stuff. To get the proper bonding between the Ti and Carbon fiber, there are some high tolerances which have to be met. Buying a stock tube wouldn't cut it, and the bonding is something I want to be very careful with. But, you are correct, there should be a cheaper way to do this.
Increasing batch size is the only way I can even offer these. The 26th axe won't be much cheaper, but the 500th will be! ;)
HTHMay 14, 2008 at 8:10 pm #1433339
Kevin sent me 2 shaft types for testing. They were wrapped at different angles to give different properties. I ran some quick tests and found the stronger one. That is the one that I used on the axe. I didn't bother including the tests as they are basically simple load tests to see which broke first.
I don't think the B-rating would be hard to achieve with a carbon shaft and Ti head. As you stated, the head and spike are up to the task, it's just the shaft that fails. There are 2 ways to solve this problem…one is to increase wall thickness, and the other is to increase the outer diameter. Both will work, and in reality, I'd have to try them out to see. The insert idea discussed above is another route.
I have the material on order, and hopefully it will be just a few weeks…depending of course on if the people still want them – let's see the reaction to the article. :)May 14, 2008 at 11:50 pm #1433370
like Nia I am torn between I want them now and cant we make it a bit better. I would have thought that as the CF tube is relatively light and the titanium relatively heavy upping the OD of the tube would cause upping the size and weight of the ferrule and spike. It would also cause redesign of more titanium which would take more time. Inserts inside the CF would leave everthing else the same and would not take so long.
You have all the data about bonding and I dont but there is so much safety margin on the tension (to pull off the spike) test, that I hoped that a small increase in area would make up for irregular surfaces. Anyway is it not easier to ream a fraction out a tube to a perfect diameter than to start from a solid rod?
I assume the Helix has an aluminium alloy spike. Kevin you sent a picture of the wear to the head of your Helix axe. Was there significant wear to the spike? You can see where I am going with this question. A reduction in production costs would not only allow your beer money it would also increase the chances of bigger sales by avoiding a price increase.May 15, 2008 at 1:03 am #1433373
Oh, I'm firmly in the "I want it now!" camp. My questions where just a matter of curiosity.
I have next to no experience in this type of thing so it's probably best to ignore what I say. In any case, the cantilever test is interesting in that the requirement to pass requires significant force almost but not quite body weight. Speaking as a rank amateur, if I'm using the pick to pull me up a near vertical face required to get to this level of force I would like a safety margin above my body weight, which is what the type t specification does.
For me this calls into question the need for a type b axe, as over built for a walking axe and not strong enough to be used as an ice tool. An axe which barely passes type b, like the 8 oz camp may be a middle ground with out much application. Anyone have any opposing views and examples of where a Steve's axe might not have the required strength but a technical ice tool would be overkill?
With that in mind, Derek's suggestion to use aluminum in the spike is interesting as we may have room to trade durability and strength for cost and weight. Aaron Sorenson complained earlier that Steve was making the axe too strong and therefore heavier and given the results of the tests he might be right.
That being said, I'd prefer sticking with the much stronger titanium for the spike though. This is the part of the axe that will get the most use during walking as a cane and for self-belay and aluminum will be dented and dulled fairly quickly as reported by others. On the other hand, an aluminum pick and adze might make sense and reduce costs considerably. The pick will mostly be used for self arrest, a hopefully infrequent event, so long term durability is less of a factor. The adze probably won't hit too many rocks while cutting steps so ok there too. I'm discounting the use as a potty trowel. The key is making sure the bonding point between shaft and head is as strong as the current model.
All speculation aside, Steve with the help of the community has made the coolest walking axe I can imagine, with capabilities in excess of what I need, verified in published test results, with a weight lower than anything else that can make that claim. So I'm very happy with the current version. Did I mention I want it now. :)May 15, 2008 at 2:58 am #1433375
> I assume the Helix has an aluminium alloy spike. Kevin you sent a picture of the wear to the head of your Helix axe. Was there significant wear to the spike?
I used my Helix during the 3 months in France, a bit for walking and a bit more for general grubbing around – clearing stuff for campsites and digging cat holes. It was the adze which did most of that work, and yes, the aluminium certainly showed some wear. The anodizing, while hard, was not able to prevent noticeable dings and dents.
The idea of trying to weld a titanium adze to an aluminium ferrule and spike … no thanks. Technically, the mismatch in the coefficients of thermal expansion makes the idea very suspect.
cheersMay 15, 2008 at 4:49 am #1433383
no you misunderstand me. Steve's nomenclature is the ferrule and pick are parts of the head and that is all important and therefore to be made of titanium. I was suggesting that the spike by which Steve means the reinforcement at the other end of the handle, the bit that touches the ice when you use it for stability, that that bit was something that was maybe overengineered. I suggested a bit of titanium tube with a slanted end glued over the CF and then asked if Kevin (who posted a picture of the head of his potty trowel blunted by short use) had an opinion as to whether the spike on his potty trowel showed significant wear in the same time.
You have used the potty trowel, do you have a view on an axe with a fully titanium head,(pick,adze and ferrule), but a simple aluminium alloy spike. From Steve's costing this could save significant production cost.
I would still prefer a titanium spike but was suggesting several ways to save money.May 15, 2008 at 9:39 am #1433408
Jeremy CleavelandBPL Member
@jeremy11Locale: Exploring San Juan talus
amazing job on the axe project! Just curious, how light could an unofficial B rated axe be, using the same Ti parts, but beefing up the handle from either aluminum, Ti, or beefier Carbon Fiber? any ideas? Most ultralight B rated axes are all aluminum, so wear becomes an issue, and a Ti head would be sweet.May 15, 2008 at 11:23 am #1433423
I buried my question in my previous post so I am putting it here separately.
The one place that the axe fails type b badly is the cantilever test with the pick fixed and force applied perpendicular to the shaft. Steve, only got to ~40 lbs while type b is 132.
My question is: is there a situation where you would not be comfortable with this lower breaking point, but satisfied with the less than body weight breaking point of type b? I'm thinking if I'm hanging from the axe I want this to hold my entire bodyweight (i.e. type t) but what are your thoughts?May 15, 2008 at 2:52 pm #1433453
> My question is: is there a situation where you would not be comfortable with this lower breaking point, but satisfied with the less than body weight breaking point of type b? I'm thinking if I'm hanging from the axe I want this to hold my entire bodyweight (i.e. type t) but what are your thoughts?
This is a WALKING axe, not a climbing axe. If you are going to be in a situation where you want to hang you bodyweight off it, use a certified axe.
CheersMay 15, 2008 at 3:19 pm #1433456
I think you might of misunderstood the point of my question. I understand what this axe is intended for. What I'm asking is that given that a walking axe, like Steve's or the ULA, exists is there any place for a a type b axe? Wouldn't the best set of gear be walking axe for trips where it provides extra security, but not the difference between life and a serious fall, and a type t for when things get rough? What is a scenario where the walking axe won't cut it, but type b provides the necessary safety margin? Would any of you be comfortable hanging off a type b certified axe?
niaMay 15, 2008 at 6:37 pm #1433487
Jeremy CleavelandBPL Member
@jeremy11Locale: Exploring San Juan talus
Nia, as I understand it, type T is generally designed specifically for ice climbing, so beyond the extra strength, it also has the recurved pick, a grip, sometimes a hammer instead of an adze, usually there is either a leash or a leashless style handle. I don't know of any traditional style axes that are type T although they are probably out there. Type B is used for general mountaineering, where self arrest is a potential need, such as roped glacier travel, steep snow, roped snow travel using techniques such as the boot-axe belay, etc.
the SUL non type B axes would in no way be suitable for self arresting a roped team of 2 or more on a glacier, using as a snow anchor in a crevasse rescue, or using with a boot – axe belay, but the short type T tools would be sub-optimal for these purposes as well. Type B and T tools also have differing angles at the point of the pick – type B is optimized for self-arrest, type T is pointier and holds better for ice climbing, but gives a more harsh self arrest in hard snow.May 16, 2008 at 3:14 pm #1433618
You could very well be correct about the CF insert being the key to better performance. I really should try it out before knocking it. Looking at it from the another view, if we increased the diameter of the shaft, we could shorten the ferrule because of the increased surface area the larger diameter would give – I wonder if it would eliminate a weight increase.
I'm not sure if I understand your comment about the safety factor for pulling the spike off.
"You have all the data about bonding and I dont but there is so much safety margin on the tension (to pull off the spike) test, that I hoped that a small increase in area would make up for irregular surfaces."
If you look back at the article, even with a 50% bonding error during assembly, it is still many times above the requirements.
You are right that it would be easier to ream a tube and cut on an angle. Then I could bond it on the outside of the shaft. I considered bonding it to the outside originally but thought that the ridge it would create would not let it slide nicely into the snow, and then be difficult to pull out at times. I'll look into it though.
I don't want to go the route of an aluminum spike as that really is one of the areas that see alot of use, especially while "walking".May 16, 2008 at 3:25 pm #1433620
Regarding your question about the cantilevered test. If you look the the way the axe is being loaded, you really wouldn't come into this configuration of loading while hanging on it. I agree that there would be some loads in that direction once you broke down the forces, and it would depend on how far you had the pick into the ice and such, but you would be hard pressed to end up using your this axe in the "bottle opening" position. Even the Type T axe only requires 0.9 kN which works out to be about 200lbs.
That being said, I am sure if you really wanted to get the Type B rating, you could design it for that – with the larger diameter shaft and testing for fatigue in certain areas.
I look at this project from different view. Since there is such a large strength difference between the shaft and the head, why can't we shave down the Ti to achieve a lower strength in return for more weight savings?May 16, 2008 at 3:40 pm #1433621
Thanks for the response. A question though. My initial thought, is that self arrest, anchor and belay don't put a huge amount of stress on the shaft, at least no more than test #5. If that's the case than this axe which we assume passes test #5 should be sufficient. Of course my assumption easily could be wrong. But, how much more confident would you be with the all aluminum camp corsa in these scenarios?May 16, 2008 at 4:07 pm #1433629
Steve, Jeremey, Roger,
I think I've done a poor job explaining myself. Here are a few scenarios I can see myself in where I'd need an ice axe.
1) early spring sierra hiking over several feet of snow and ice. Axe used for cane and cross body as well as possible self arrest.
2) Glacier travel. Same as above with the addition of a snow anchor and boot axe belay.
3) Short periods of ice climbing such as a waterfall, mixed with (2).
4) Serious ice climbing scaling 100s or 1000s of feet.
Which axe would you use in these scenarios? I seriously doubt I will ever attempt (4). I'm sure I can use Steve's axe for (1). So what sort of gear would I need for (2) and (3)?
If a lightweight B rated axe (camp corsa) is sufficient in these scenarios than I could have one axe to cover everything I would do and adding an oz or two would be a reasonable trade off for less gear in my toolbox. In this case I'd like to see Steve sacrifice a little weight for strength. Even if this was the same weight as the corsa it would be my preference for Ti over Al.
If I would need a heavier axe for (2) or (3) (lightest T I've seen is about 16 oz), than saving 12 oz for (1) would definitely be worth owning a seperate tool. In this case I'd like to see Steve shave an oz or so off his axe at the expense of some strength.
Finally I'll add that this is Steve's axe and he can build it however he wants to.May 16, 2008 at 4:39 pm #1433638
A few questions:
(1) What is the weight of the carbon fiber shaft?
(2) You mentioned that the shaft has a maximum stress capacity of 122,000 psi. What is the corresponding capacity for a 1" shaft?
(3) What is the weight of a 1" shaft?May 17, 2008 at 1:36 am #1433672
> You are right that it would be easier to ream a tube and cut on an angle.
However, this could be counter-productive, for reasons of the available alloys.
I think the spike is made of 6Al4V alloy at present, like the head (correct me if I am wrong Steve). This alloy is HARD! A lot of Ti tubing is made of CP titanium (commercially pure) and this stuff is a LOT softer. I know: I am machining the stuff myself. Frankly, I would far prefer to know that the spike is HARD.
CheersMay 17, 2008 at 1:36 am #1433673
I personally am happy with the head end, come to that the whole axe.
About the spike end, your response to my suggestion to just use stock tube to save machining on the spike was that the epoxy needed close tolerances. What I was trying to get across was that you seemed to have allowed for less than perfect tolerances by assuming 50% reduction of bonding and then showing the spike was still 7 times more well glued. It is so simple and cheap to just glue titanium tube over the CF I thought it was worth a trial, come to think of it not even a whole axe just a bit of cf tube and a bit of titanium tube. I think if you tried the original bonding area and it just failed it would still be best to just lengthen the spike tube overlap a bit to get more area. If the cantilever load on the spike end is important a CF insert in that end too should help but I think the spike end is not under the strain of the head end.
I come from a family of cycle frame builders, everything strong was double butted when I was young, so I instantly go for the insert over the bigger tube out of prejudice/experience.
The ridge produced is not ideal but perhaps wrap some protection round the CF to loose it?
I also think and Al spike would not be as good as Ti that was throwing out ideas to your response that machining Ti was expensive, and feeling the spike could be cheaper.
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