Author Topic: In progress elm Holmegaard  (Read 30344 times)

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Offline Dane

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Re: In progress elm Holmegaard
« Reply #15 on: February 02, 2009, 11:06:54 am »
All the work is being shouldered by a relatively short section of each limb. If the wood can handle it I guess that's fine (though I think it will eventually fail in this case), but I personally would make the non-working part of the limbs shorter to spread the load out a little more.

I have been thinking about this, and wonder about the value of shortening the outer limbs. Since they act as levers, wouldn't longer be better than shorter? A longer lever lets you lift a heavier load, right? And wouldn't a shorter outer limb also put more stress on the working portion of each inner limb?

Any ideas there?
Greenfield, Western Massachusetts

John B.

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Re: In progress elm Holmegaard
« Reply #16 on: February 02, 2009, 11:30:37 am »
I'd suggest you need longer inner limbs AND shorter non-working tips.

Anybody got a wood stretcher handy?  ;)

Offline Barrage

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Re: In progress elm Holmegaard
« Reply #17 on: February 02, 2009, 11:42:33 am »
All the work is being shouldered by a relatively short section of each limb. If the wood can handle it I guess that's fine (though I think it will eventually fail in this case), but I personally would make the non-working part of the limbs shorter to spread the load out a little more.

I have been thinking about this, and wonder about the value of shortening the outer limbs. Since they act as levers, wouldn't longer be better than shorter? A longer lever lets you lift a heavier load, right? And wouldn't a shorter outer limb also put more stress on the working portion of each inner limb?

Any ideas there?

My opinion is that there is a balance required between the long non-bending tips and the working section.  If you're happy with the set and performance and it holds together, I guess that's a good balance for you.  Plus you can always tweak on the next bow and see if you like a different ratio better.  My two cents...
Travis

Offline Badger

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Re: In progress elm Holmegaard
« Reply #18 on: February 02, 2009, 11:59:18 am »
    I believe the logic in a holmgarde or any bow for that matter is the same, where the limb gets wider is should bend more, if limbs are paralell in width they should get thinner and bend more until they start to narrow and at that point stiffen up again. The front view of the holmie is telling you how to tiller it. I hate to say anything critical because all the work we do here is worth sharing but I also hate to see a new person think that is correct tiller. What would be the reason for leaving those mid outer limbs wide if they are not bending? There is no good reason. You just can't put that much bend in such a small area without destroying the wood in that area, it may not look bad but the wood has gotten weaker. Steve

Offline Dane

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Re: In progress elm Holmegaard
« Reply #19 on: February 02, 2009, 01:07:48 pm »
Badger, is there really only one correct tiller for this kind of bow? If so, all Holmgaards have to look pretty much identical, or they would be considered a failure if they don't conform to that standard. Suppose a bow of any given style breaks some rule, and yet still functions for many thousands of arrows and years. Is it then a success, or an abberation?

All this is about learning. My first instinct is to keep it the way it is, and see how long the relatively sharp bend lasts; it is only wood, after all. But, I will re-tiller the inner limbs with a cabinet scraper, and then go ahead and put a finish on it and call it done. I will loose some weight by removing more wood, but that is okay in this case, since I am not hunting any critters. The speed from this design I think mitigates that a bit for decent cast.

I won’t touch the outer limb length, though. Since they are levers, longer seems intuitive to me, and as adb well points out, a Holmgaard-looking bow is not a Holmgaard. My next bow of this design, I’ll try different ideas. I have some maple and some hickory in stave form and some lemonwood and osage in board form, any of which I may use.

I wonder if there is an optimal ratio between inner and outer limbs, handle length, and fade lengths? Wood species of course has to play some role.

Wood stretcher, John? :) I think the Spanish Inquisition used those, but they are highly barbaric, and banned by most countries and The Hague.

Dane


Greenfield, Western Massachusetts

Offline Gordon

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Re: In progress elm Holmegaard
« Reply #20 on: February 02, 2009, 01:30:49 pm »
Dane, I understand what you are saying about the use of stiff tips as levers. The problem with your implementation, however, is that the springs that propell the levers, i.e. the working limbs, are not up to the task. The high degree of set in your photos show that they are already breaking down. The other problem is that the advantages of longer and longer levers must be balanced with the performance cost of increased mass. It looks to me that there is a lot of unnecessary mass in the mid and outer limbs which will rob your bow of cast. There is nothing fundamentally wrong with a Holmgaard design if all aspects of the design are kept in proper balance in the implementation.
Gordon

Offline Badger

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Re: In progress elm Holmegaard
« Reply #21 on: February 02, 2009, 01:47:23 pm »
Dane, I am not trying to discourage you in anyway, it is a learning process, I probably screw up more tillers than anybody here. You asked is there is just one correct tiller for a particular design. I think the answer to that is yes, there is only one correct tiller that will match the front view of any bow. There are many tillers that will work without failing! I don't think any of us have built a perfect bow unless we just lucked out. But there is logic that goes into all designs. You have a wide outer limb right before it narrows that is stiff!! If it were very narrow I would say it was ok, but then your bending area would need to be much wider than it is now. I would just shoot the bow and enjoy it as I imagine it shoots pretty well, but we would be doing a disservice to any one new watching these threads to say that is correct, it is not correct. When you are tillering out a bow at the first sign of getting set you need to start getting more limb working, you had plenty of wood closer to the handle that could bend and you had plenty of wood near the spot where it narrows that could be bending, the width is there, if I were going to rework that bow I would simply shorten it a couple of inches and narrow that wide potion of the inner limb until it starts to flex a bit, i would then get the inner limb working a bit more, but the damage has allready been done. Steve

Offline rkeltner

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Re: In progress elm Holmegaard
« Reply #22 on: February 02, 2009, 02:23:49 pm »
i'm impressed with this holmgaard! in some ways it reminds me of the radical build that tim baker did in tbb 4, except he did some wild things with horn and sinew. while i your working limbs look short, they look like they are bending smoothly through their bend. iwould be suprised if this bow isn't a sweet shooter!

DCM

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Re: In progress elm Holmegaard
« Reply #23 on: February 02, 2009, 05:09:51 pm »
Bearing in mind the sensitivity inherent in any budding bowyer, I think the holm may be one of the hardest designs to really optimiize, in terms of crafting, and this one left a lot on the table.  Generally any bow project where your wood sets more than 2" start to finish, assuming good crafting, materials and moisture control, you probably should have started with more wood, or finished with less bow.  Plus, you can just look at this one and see 2/3 of the limb slingin' around not toting any work at all.

The mass in the width transition has to be dead nuts on, or you negate the relative advantage of the design.  And, obviously, one must design in enough wood on the inner limb to take the load.  I've yet to see one I thought perfectly executed.  I think folks would be better served building simple flatbows at first.  In fact, I think simple flatbows demonstrate the holm design better in practice than the abrupt width transition, pronounced tiller of the arctypical projects.

But then I also think a fella should do whatever he's a mind to, and not pay too much attention to what's said about it.  It takes longer that way, but you do come away with a sense of certainty, and fulfillment, by having "touched all the bases" all by yourself.


Offline Little John

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Re: In progress elm Holmegaard
« Reply #24 on: February 02, 2009, 09:48:58 pm »
In this design I think the inner working limbs need to be wide enough, long enough, and each inch doing its share of the work, as you are doing a lot of bending in a relitively short distance. The non working levers need to be very low mass and bend only ever so slightly to let you know you have reduced the mass as much as possible. Actually my inner non working limbs do work a little, and you need to get the inner limbs working very quickly out of the handle but not so much to take set. I love holmies but have only made a couple and not perfect ones, but have one or two in the works.    Kenneth
May all of your moments afield with bow in hand please and satisfy you.            G. Fred Asbell

Offline Badger

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Re: In progress elm Holmegaard
« Reply #25 on: February 03, 2009, 12:05:39 am »
I finished up one last week I will try and post tomorrow. 60" nock to nock 65#@27". They make a nice bow especially when they are a little on the short side.

a finnish native

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Re: In progress elm Holmegaard
« Reply #26 on: February 03, 2009, 05:40:49 am »
nice bow, dane! good to see some of your work again.

Offline George Tsoukalas

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Re: In progress elm Holmegaard
« Reply #27 on: February 03, 2009, 09:39:37 am »
Badger:
" I probably screw up more tillers than anybody here. You asked is there is just one correct tiller for a particular design. "
I bet I have you beat per capita. LOL.
Dane, I don't think anyone has seen the tiller of the original Holmgarde but I don't know about that. LOL. I also have never made one of that design. Looks like you have plenty of limb for a 26 -27 inch draw. I'd say you did a great job on that. Well done. :) Jawge

Set Happens!
If you ain't breakin' you ain't makin!

Offline adb

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Re: In progress elm Holmegaard
« Reply #28 on: February 03, 2009, 06:54:51 pm »

I have recieved a PM from Dane, and he states he is very discouraged with some of the responses to his postings on this bow. Discouraged, in fact, to the extent that he may give up making bows, and certainly not posting anymore efforts here. I think as experienced bowyers, we have an obligation to encourage the efforts of new bowyers. I try to leave feedback in a first person context, stating: "If this was my bow, I might do this..." That way, the person recieving the feedback can either use it if it works for them, or disregard it if it doesn't, without feeling resentful or offended. I think, instead of saying something is not correct, we can say how we might make something better. Personally, I think Dane has done a pretty decent job of tillering this bow. The Holmegaard is a rather difficult tiller, and certainly not a beginners bow. Much contention swirls around this design, as to what is "right.''

As far as set goes, poor tiller is not the only factor. It is an important factor, but far from the only thing that will cause set. I recently finished a yew selfbow, 72" ntn, 50#@28". Nothing radical or demanding, but after finishing, the bow has 4" of set. The tiller is perfectly circular, with a bending handle and all portions of the limbs working. The problem was low density wood, and too much moisture. The stave was not as dry as I thought. Also, on a proper Holmegaard, I measure set at the end of the working limb portion only... not at the nock like is normally done. So, to me, Dane's bow does not appear to have more than the conventional 1" - 2" of set.

I also believe there are many ways to tiller a bow. Elliptical tiller, circular tiller, +/- tiller, symmetric limbs, asymmetric limbs... many options exist, but none are wrong. Some hard and fast rules do exist, but the fun thing about all this is, there are many interpretations.

I think we should applaud new members and their efforts, and offer feedback which is helpful, rather than offensive.
« Last Edit: February 03, 2009, 07:17:56 pm by adb »

Offline sailordad

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Re: In progress elm Holmegaard
« Reply #29 on: February 03, 2009, 07:15:46 pm »
i guess i dont see how any post were offensive or discouraging.
he asked in his post what people thought.i gave my opinion as did others.
i dont believe in sugar coating as this will cause one to develop bad bow building habits.
when i post a bow and want feed back, i dont want it to be false info. i want to know the truth and assume thats what others want
when they post and ask questions about the bow they are building.
i figure creative people can deal with constructive criticism
i always wanted a harley,untill it became the "thing to ride"
i ride because i love to,not to be part of the crowd