Tillering the Holmegaard Bow

How to make a Bow, a String or a Set of Arrows. Making equipment & tools for use in Traditional Archery and Bowhunting.

Moderator: Moderators

Post Reply
Message
Author
User avatar
erron
Posts: 3299
Joined: Wed Jul 23, 2003 10:33 am

Tillering the Holmegaard Bow

#1 Post by erron » Sun Jul 17, 2005 8:22 pm

Thanks to Dennis La Varenne for this article! :) 8)
Last edited by erron on Tue Aug 16, 2005 9:43 am, edited 3 times in total.

Dennis La Varenne
Posts: 1776
Joined: Sun Sep 07, 2003 10:56 pm
Location: Tocumwal, NSW. Australia

Re: Tillering the Holmegaard Bow

#2 Post by Dennis La Varenne » Wed Oct 20, 2010 12:57 am

To all,

I have now re-edited my original paper on tillering the Holmegaard (Mølegabet) bow which is attached.
2010 10 11 - Tillering the Holmegaard Bow.pdf
(694.73 KiB) Downloaded 878 times
The body of the text has only minor changes, but the article is better laid out with a Contents page and a preface to this, the 2010 edition acknowledging the work of Dave (Yeoman) Clark in his Ozbow series on using mathematics in making bows.

I was also very gratified to discover recently that my article has been used as a reference source on Wikipedia, on such sites as PaleoPlanet and elsewhere if you google the title.

I have deleted the original article at the start of this thread.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

What is the difference between free enterprise capitalism and organised crime?

HOMO LVPVS HOMINIS - Man is his own predator.

User avatar
greybeard
Supporter
Supporter
Posts: 2992
Joined: Tue Feb 07, 2006 9:11 am
Location: Logan City QLD

Re: Tillering the Holmegaard Bow

#3 Post by greybeard » Sun Oct 24, 2010 10:56 pm

Hi Dennis,

Thank you for resurrecting your 2005 document regarding the tillering of the Holmegaard Bow.

I accept the fact that your paper covers the bow on the tiller board.

For all intents and purposes the Holmegaard appears to take on the form of a flat bow that has been mated with a longbow.

It is intriguing that the mystery of such an ancient bow design requires the use of a computer and mathematical formula to replicate the craft of the ancients.

I note that you are quite emphatic that during the tillering process the “two outer straight levers do not bend.”

"1. ANATOMY OF THE HOLMEGAARD BOW
The Holmegaard comprises five distinct sections –
a handle section which does NOT bend.
two inner limbs which DO bend, and
two outer straight levers which do NOTt bend.
The reason my first attempt failed was because it developed serious frets across the middle of the wide inner limb section because of tillering errors. Unlike full-limb bending designs, this short wide inner limb section in the Holmegaard is that which bears all of the bending load, and is the reason it is made wide and parallel.
The outer half of the limbs are much narrower and step down from full width at mid-limb then taper to a point. This gives this design much of its advantage in quick limb recovery because of its arrow-speed conserving low outer tip mass. Wider blunt tips would defeat the inherent advantage of this design.
The narrow outer half of the Holmegaard limb DOES NOT BEND. Consequently, it remains parallel in thickness or even thickens progressively but slightly toward the tip – just enough to give it the rigidity it needs to be a lever – and then reduces to a point in the last couple of inches to keep tip mass low.
"

I have taken the liberty of placing blue lines on the section of limbs that do not bend when the bow is on the tiller board.
Holmegaard On Tiller Board.jpg
Holmegaard On Tiller Board.jpg (65.65 KiB) Viewed 43996 times
Does this profile [for the outer straight levers] remain true when the bow is at full draw?

If not, can you give some indication of how much bend one could expect?

As there are no original bows that are able to be shot I guess that we can only surmise what may have been.

Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

Dennis La Varenne
Posts: 1776
Joined: Sun Sep 07, 2003 10:56 pm
Location: Tocumwal, NSW. Australia

Re: Tillering the Holmegaard Bow

#4 Post by Dennis La Varenne » Mon Oct 25, 2010 4:26 am

Daryl,

Thank you for the interest you have shown in the article.

My insistance of keeping the two outer halves of the limbs as non-bending levers is an assumption on my part derived from my reading and investigation of this bow design which, in fairness I should have kept a record of and inserted as footnotes in the paper for others to follow up on if they desired to see where I drew my conclusions about its design and the cleverness of its design from. I did not and that is a cross against my name.

The most current thinking among the bowyering community internationally rightly or wrongly, has accepted as orthodoxy that this stiff outer lever principle is the basis of the design, and I have followed that orthodoxy because the reasoning behind it makes good sense to me and has two practical benefits in allowing a reasonably short/medium length bow to have a moderately more shallow string angle coupled with low outer limb mass which is beneficial toward higher limb speed and hence arrow speed.

Of course, you are quite correct in considering that there is not the slightest reason that this bow cannot also be made with bending outer limbs like any other flatbow design. The lower outer limb mass would still be maintained, but at the expense of a slightly greater string angle at full draw, which, depending on the n-n length of the bow, may or may not be significant. But, if one wants to build this design of bow as short as possible for simple handiness, the non-bending outer lever principle will have a positive value in terms of minimization of finger pinch and stacking.

You are also right in your inference that it is not necessary to build these bows to mathematical model to be successful in making one. Clearly our European neolithic ancestors did not and nor do we. However, using the mathematical methods explained by Dave Clarke in his series on Using Maths to Build Bows, does allow bows to be built to a blueprint within the elastic limits specific to the particular piece of wood we have in our hands, and, also not to be dismissed, to be able to make analytical models of various bow designs and make predictions with considerable accuracy on how they will bend and where to distribute the bending loads to best effect.

Maths is a valuable tool we now have to apply to our ancient craft both retrospectively to analyse the mechanical advantage of any particular design compared to any other design. Applied mathematics is the reason we can understand the cleverness of the Holmegaard design because it allows us to understand how the distribution of bending loads inherent to this design can allow maximum performance from an all wood bow compared to other bow designs extant in that same period, principle of which, in my view, is low outer limb mass to allow maximum arrow speed coupled with shallow string angle in a moderately short bow. Maths explains the WHY of this design in detail.

I have insisted in the body of the text that the inner bending section of the limbs of this design should be both parallel in width and thickness. In my introduction to the revised 2010 edition, I describe how this in not necessary, and how, using mathematical modelling based on distribution of bending load within the elastic limits of any piece of wood where the modulus of rupture is known, that there actually should be either tapering of width or thickness or a combination of both. Before I got my head around what Dave Clarke was explaining, together with some of the maths explained in Robert Elmer's 'Target Archery' and some other publications on using applied maths in bowmaking, I found that keeping the inner limb parallel in both width and thickness the most expedient way in which to tiller this design successfully, and I recommended this technique on that basis.

This recommendation on my part does not preclude any other tillering method and the success of any technique is that you end up with a functioning durable bow. Applied maths can be thought of as a finessing of the design for optimum performance for the most economical use of materials. I would be the last person to decry the work of any bowyer who produces an obvious Holmegaard design bow which functions. That would be just plain arrogance on my part, because we all know that cats can be skun in a number of ways.

I have recently come on a web discussion (again I did not note down the URL) that the characteristic Holmegaard design with which we have become familiar is most probably a deviant non-typical variant of a more common design from the same area which does NOT have the characteristic mid-limb steps and another discussion on paleoplanet which purports pretty convincingly to me that the only genuinely typical design of this bow is from another archaeological site called Mollegabet. The well known artefact from the Holmegaard site does NOT have the characteristic mid-limb steps with 'define' this design. So, the worms are now crawling from the opened can.

Nevertheless, among trad bowyery, we have been presented with a design of bow with or without mid-limb steps depending on the extent of one's archaeological PC perspective which has clear mechanical benefits and which design seemed to get lost over time until it was resurrected in the 1920s by the likes of Clarence Hickman, Paul Klopsteg and Forest Nagler who decided to investigate just what made a bow do what it does and why using applied maths. They ended up re-discovering that the most mechanically efficient designs were flatbows of firstly isosceles pyramidal shape followed by a more practical shape which had nearly parallel sided limbs for around half their length with sharply tapering outer limbs - very reminiscent of the various Holmegaard artefacts.

Our Holmegaard ancestors were pretty bright people and they managed to hit upon a design which, according to Tim Baker and Paul Comstock and others endured for something like 4,000 years then seemed to drop out of the archaeological record thereafter for whatever reason. Clearly intuition based on experience allowed some cleaver neolithic bowyer to come up with the bow based on empirical evidende, but is is largely due to applied maths that we are now able to understand the benefits of the design as well as we do today. We don't need maths to build these bows quite obviously, but it allows us to understand WHY the design is so good.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

What is the difference between free enterprise capitalism and organised crime?

HOMO LVPVS HOMINIS - Man is his own predator.

User avatar
greybeard
Supporter
Supporter
Posts: 2992
Joined: Tue Feb 07, 2006 9:11 am
Location: Logan City QLD

Re: Tillering the Holmegaard Bow

#5 Post by greybeard » Tue Oct 26, 2010 4:45 pm

Dennis,

I agree with you regarding keeping the outer limbs straight.

With the bow I have in progress I will significantly reduce the thickness of the inner limbs which in turn should stiffen the outer limbs. Although I will have to sacrifice poundage, a lighter weight bow that works is better than having a heavy one that does not.

It is a little bit of a juggling act keeping the outer limbs stiff without having too much mass.

Hopefully I will be able to post photos of a working Holmegaard.

Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

User avatar
twisted limb
Posts: 42
Joined: Mon Oct 18, 2010 12:24 pm
Location: Bowral NSW

Re: Tillering the Holmegaard Bow

#6 Post by twisted limb » Sun Aug 21, 2011 10:35 am

Black locust holmegaard inspired by Dennis' article.65"NTN, 44#@26", 1 1/2" wide.
It took about 2" of just unstrung set but shoots very sweetly, probably should have made the limbs wider to prevent set.
Attachments
2010_1020Image0009.JPG
2010_1020Image0009.JPG (107.96 KiB) Viewed 43791 times
2010_1020Image0015.JPG
2010_1020Image0015.JPG (112.93 KiB) Viewed 43791 times
2010_1020Image0008.JPG
2010_1020Image0008.JPG (112.42 KiB) Viewed 43791 times
2010_1020Image0011.JPG
2010_1020Image0011.JPG (105.71 KiB) Viewed 43791 times
2010_1020Image0014.JPG
2010_1020Image0014.JPG (113.69 KiB) Viewed 43791 times
2010_1020Image0013.JPG
2010_1020Image0013.JPG (112.95 KiB) Viewed 43791 times

longbow steve
Posts: 3116
Joined: Tue Jan 30, 2007 3:29 pm
Location: BLUE MOUNTAINS

Re: Tillering the Holmegaard Bow

#7 Post by longbow steve » Sun Aug 21, 2011 10:39 am

Nice :D , I look forward to checking it out at Wisemans. I will try to get mine done if the stave is dry. Steve

Dennis La Varenne
Posts: 1776
Joined: Sun Sep 07, 2003 10:56 pm
Location: Tocumwal, NSW. Australia

Re: Tillering the Holmegaard Bow

#8 Post by Dennis La Varenne » Sun Aug 21, 2011 5:42 pm

Mr Deer,

Well done, indeed. I love the shape at full draw. You have achieved a really nice Holmegaard-MØllegabet shape and are to be congratulated indeed. Not many can do this very well, and you certainly have. Also, the quite shallow string angle inherent to this design is quite apparent in your bow at full draw with a string angle of 130 degrees in a bow of only 65 inches n-n. It has the string angle of a very long bow on a relatively short one. This is the sort of string angle you see on ELBs and EWBs.

May I make a few observatiions . . .

Firstly, you have put steps at the start of the outer limb which are not really necessary to keep the outer limb stiff. In my paper on page 7 you will see some diagrams where I show that the outer limb can be built to maintain stiffness simply by slowly increasing its thickness out toward the tip.

Your technique will probably have simply increased the outer limb mass which will slow them down unnecessarily. Progressively thickening the outer limb still achieves the required stiffness and rigidity but keeps outer limb mass to a minimum necessary to maintain rigidity.

If you would like to try this technique on your next bow, you will see what I mean. If you did it on this one, you would lose surprisingly little draw weight if you are careful. To NOT lose draw weight, you will need to ensure that the outer limb is always gaining thickness right from where it leaves the inner limb until it reaches the string nocks.

The outer limb must NEVER decrease in thickness anywhere along its length over that portion behind it or you will lost both rigidity (and perhaps some draw weight) because the outer limb will want to bend at that point.

Secondly, on your diagram of your bow at brace, I note that you have correctly tillered the bow to have a slightly weaker upper limb. This can be seen by the amount of bend in the inner limb as shown by the area between the limb and the red lines I have drawn.

In Photoshop, I have rotated the image so that the string is at exactly 90 degrees perpendicular in the picture (see pic 2010_1020Image0013_b.jpg below).

However, in the next pic (2010_1020Image0014_b.jpg) the bow seems to have reversed its tiller judging by the red lines drawn in the same places. At full draw, as shown by the perpendicular green line, your lower limb tip is well ahead of the upper, suggesting strongly that you are pushing the lower limb forward of the upper limb.

This can mean either of two things -

1. that you 'heel' your bow very badly at full draw forcing the lower limb to belly out further in front of the upper limb which will cause it to take a significant set in the lower limb, or

2. that the bow is canted with the upper tip toward the camera which causes a degree of distortion in the shape of the limbs from this angle.

But, your grip does not look like a heel down grip at all . . . more like an adaption from a high wrist grip with the bow pivoting on the web of your bowhand which is good.

Heeling your bow will also put the limb synchrony out and both limbs will move at different speeds because they have different bending loads on them. You may feel this as a bit of a kick at the end of the arrow stroke - usually termed handshock.

At full draw, both limbtips should be on the same vertical plane - not one ahead of the other - for the limbs to have the same bending load on each. That is why we tiller bows - limb synchrony - not nice shape. Symmetry of shape indicates synchrony.

Equal bending load = equal limb speed where all else is equal.

However, if you do 'heel' your bow (even though your grip does not suggest it), please be careful and observe it closely over time to check that it does not develop a set in the lower limb. If you are a heel shooter, you will need to stiffen your lower limb even more by shortening it so it is stiffer and more resistant to being pushed ahead of the upper limb.


Good work otherwise.
Attachments
2010_1020Image0013_b.jpg
2010_1020Image0013_b.jpg (446.26 KiB) Viewed 43775 times
2010_1020Image0014_b.jpg
2010_1020Image0014_b.jpg (393.25 KiB) Viewed 43775 times
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

What is the difference between free enterprise capitalism and organised crime?

HOMO LVPVS HOMINIS - Man is his own predator.

User avatar
twisted limb
Posts: 42
Joined: Mon Oct 18, 2010 12:24 pm
Location: Bowral NSW

Re: Tillering the Holmegaard Bow

#9 Post by twisted limb » Sun Aug 21, 2011 6:54 pm

Thanks Steve, and I look forward to catching up with you at Wisemans.
Dennis thankyou for your detailed critique of my bow.Sorry about the poor quality photos.
It's my third sucessfull selfbow and I really enjoyed making it.Must admit I am tillering my bows by eye and should start to approach the process a little more clinically.It does shoot quite sweetly though and very quietly.
I think I will reduce the outer limb mass for a bit more speed and have another look at the even limbtips at full draw.
Got another one on the go in Hickory Wattle with a bit wider limbs and a longer handle.
Thanks again really appeciate your comments.

John Deer

Dennis La Varenne
Posts: 1776
Joined: Sun Sep 07, 2003 10:56 pm
Location: Tocumwal, NSW. Australia

Re: Tillering the Holmegaard Bow

#10 Post by Dennis La Varenne » Sun Aug 21, 2011 7:21 pm

John,

When you have your bow on the tiller and draw out, are the tips on a plane 90 degrees to the tiller? If so, where the string sits on the tiller is where you should have your drawing fingers.

The only way to get around this is to have an offset tiller which allows for the fact of the drawing hand being a bit higher than the bowhand. This drawing force applied somewhat across the vertical axis of the bow if you like, puts an uneven drawing load on each limb. This is why so often when we take a bow from a straight stick tiller and start drawing it, the limbs behave very differently to when they are on the tiller.

If you see my article on Ozbow http://www.ozbow.net/phpBB3/viewtopic.p ... set+tiller, you can build yourself an adjustable offset tiller which can be exactly adapted to your particular drawing style while you are tillering your bow. It will result in a bow which when it comes off the tiller and is drawn, draws exactly the same as when it was on the tiller.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

What is the difference between free enterprise capitalism and organised crime?

HOMO LVPVS HOMINIS - Man is his own predator.

User avatar
twisted limb
Posts: 42
Joined: Mon Oct 18, 2010 12:24 pm
Location: Bowral NSW

Re: Tillering the Holmegaard Bow

#11 Post by twisted limb » Sun Aug 21, 2011 9:51 pm

Dennis
had a look at the string and the nocking point is almost a full inch higher than it needs to be and adjusting it down will bring it within 1 1/2" of the dead center of the string, this should have a positive effect on the tips.It's not the bow hand as I am shooting out of the web.
Thanks for your thoughts.
John.

Dennis La Varenne
Posts: 1776
Joined: Sun Sep 07, 2003 10:56 pm
Location: Tocumwal, NSW. Australia

Re: Tillering the Holmegaard Bow

#12 Post by Dennis La Varenne » Mon Aug 22, 2011 12:54 am

John,
had a look at the string and the nocking point is almost a full inch higher than it needs to be
That will do it.

I did think of a too-high nocking point, but thought, no . . . people usually get that pretty right. So I didn't bother mentioning it and I should have. Slap my wrists.

Few people understand the effect too-high a nocking point will have on the balance and synchrony of the limbs.

Because you have essentially a pivot grip on the web of your bowhand, the high nocking point will tend to pull the upper limb toward you and pivot the lower limb away with the effect on the shape of the bent limbs illustrated above. This has exactly the same effect as heeling the bow. and can obviously come about other than from incorrect tillering.

I think you will get this little beast shooting very well indeed. Just be careful with the thinning and tapering of the outer limbs. With care, you may not lose any draw weight at all. Do please keep us posted.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

What is the difference between free enterprise capitalism and organised crime?

HOMO LVPVS HOMINIS - Man is his own predator.

Dennis La Varenne
Posts: 1776
Joined: Sun Sep 07, 2003 10:56 pm
Location: Tocumwal, NSW. Australia

Re: Tillering the Holmegaard Bow

#13 Post by Dennis La Varenne » Fri Jun 22, 2012 7:17 pm

It was with some considerable surprise that I found on doing a recent websearch on my name for another purpose, that my article above on 'Tillering the Holmegaard (Mølegabet) Bow' has become something of an international reference on the subject - even on the Society of Archer Antiquaries website of all places. I don't know what to make of it.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

What is the difference between free enterprise capitalism and organised crime?

HOMO LVPVS HOMINIS - Man is his own predator.

User avatar
bigbob
Posts: 4098
Joined: Sat Jul 10, 2010 8:55 pm
Location: sunshine coast

Re: Tillering the Holmegaard Bow

#14 Post by bigbob » Fri Jun 22, 2012 7:33 pm

Great to see your expertise being acknowledged by your peers.
nil illigitimo in desperandum carborundum
razorbows.com

Dennis La Varenne
Posts: 1776
Joined: Sun Sep 07, 2003 10:56 pm
Location: Tocumwal, NSW. Australia

Re: Tillering the Holmegaard Bow

#15 Post by Dennis La Varenne » Fri Jun 22, 2012 7:37 pm

Very kind of you bigbob.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

What is the difference between free enterprise capitalism and organised crime?

HOMO LVPVS HOMINIS - Man is his own predator.

longbow steve
Posts: 3116
Joined: Tue Jan 30, 2007 3:29 pm
Location: BLUE MOUNTAINS

Re: Tillering the Holmegaard Bow

#16 Post by longbow steve » Tue Jan 01, 2013 7:11 pm

http://www.academia.edu/1919841/Hjarno_ ... ns_Fjord_D
Thought I would add this link to this thread for a visual of the bow artifact.

User avatar
Stickbow Hunter
Supporter
Supporter
Posts: 11637
Joined: Sat Jul 26, 2003 8:33 pm
Location: Maryborough Queensland

Re: Tillering the Holmegaard Bow

#17 Post by Stickbow Hunter » Tue Jan 01, 2013 7:44 pm

Great link. Thanks Steve.

Jeff

User avatar
bigbob
Posts: 4098
Joined: Sat Jul 10, 2010 8:55 pm
Location: sunshine coast

Re: Tillering the Holmegaard Bow

#18 Post by bigbob » Wed Jan 02, 2013 9:29 am

Very interesting! Unusual to have no cut in nocks, so may have been under construction.
nil illigitimo in desperandum carborundum
razorbows.com

longbow steve
Posts: 3116
Joined: Tue Jan 30, 2007 3:29 pm
Location: BLUE MOUNTAINS

Re: Tillering the Holmegaard Bow

#19 Post by longbow steve » Wed Jan 02, 2013 10:10 am

Hi Bob, they may have been tie on nocks of sinew or the like? I don't recall if the first artifact had nocks or whether the tips were intact. This is the second bow of this design found now. Steve

Post Reply