THE 1: 0.625 or 5/8 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
greybeard
Supporter
Supporter
Posts: 2992
Joined: Tue Feb 07, 2006 9:11 am
Location: Logan City QLD

THE 1: 0.625 or 5/8 BOW.

#1 Post by greybeard » Tue Apr 14, 2020 2:58 pm

I am not sure of the exact time line of when and why this ratio for limb cross sections came into being. Reference has been made that it was used in target archery during the Victorian era to define what constituted a target longbow. If anyone as more information could you please let me know.

Perhaps this ratio was best suited to target longbows made from northern hemisphere woods.

The ILAA and BLBS use this measure in their definition of a longbow.
4 Limb Cross Section Of Bow.jpg
4 Limb Cross Section Of Bow.jpg (84.62 KiB) Viewed 4378 times
Building a laminated longbow using hardwoods for belly material could create its own problems. Unless we try we will never know.

Pole bamboo was used as a backing, tapered vertically laminated bamboo as core material with Balau and Purple Heart for the belly.
1 Compilation.jpg
1 Compilation.jpg (212.24 KiB) Viewed 4378 times
The bow was glued up with approximately 1 ½ inches of reflex built in.
2 Tip.JPG
2 Tip.JPG (56.4 KiB) Viewed 4378 times
With the belly wood being quite a bit over thickness most of the reflex was lost when the bow blank was taken off the form.

At this stage the belly timber overpowers the backing and core. However the backing and core retain a ‘memory’ of being in reflex. As the belly wood is gradually removed the reflex starts to return.

Once the blank was sanded to the limb plan belly wood was removed to bring up a ‘D’ section. A Spokeshave is an excellent tool for removing excess wood.

3 Scrapings.JPG
3 Scrapings.JPG (133.57 KiB) Viewed 4378 times
My first attempt at the tiller stick indicated that a lot more timber would need to be removed. When finally getting the limbs to bend to brace height I estimated the draw weight at this point was in the vicinity of 40 to 50lbs.

Obviously a lot more belly wood needed to be removed to get the draw weight to around 50# @ 28”. At this stage it may be necessary to reduce the limb width in order to maintain the 1: 0.625 ratio as belly wood is removed. The narrower a limb becomes the more susceptible it is to twisting. During the process of removing belly wood it is important that the ‘D’ cross section remains symmetrical.

The limbs were bending fairly evenly to brace height so now was the time to go to the correct length string.

Tip overlays are fashioned from African Blackwood. This timber is extremely hard [Janka Hardness: 3,670 lb (16,320 N)] and is ideal for tip overlays when low stretch string material is used.

From the Wood Data Base. The actual number listed in the wood profile is the amount of pounds-force (lb) or newtons (N) required to imbed a .444″ (11.28 mm) diameter steel ball into the wood to half the ball’s diameter. This number is given for wood that has been dried to 12% moisture content, unless otherwise noted.
6 Janka Hardness.jpg
6 Janka Hardness.jpg (10.29 KiB) Viewed 4378 times
After bracing the bow, with difficulty and exercising the limbs tiller was just less than half an inch out. First task was to get the limbs into tiller and continue on reducing the draw weight.
5 Flipped Image.jpg
5 Flipped Image.jpg (70.11 KiB) Viewed 4378 times
Presently the bow draws 56# @ 28” DLPP and has zero tiller.

As the draw weight is far too heavy for me the bow can go on the rack and the tiller can be adjusted if I get a buyer.

I will endeavour to get a younger club member who shoots 60# plus traditional bows to shoot the bow in for me and see if the tiller changes.

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

Re: THE 1: 0.625 or 5/8 BOW.

#2 Post by Stickbow Hunter » Tue Apr 14, 2020 9:09 pm

Can't help you with the time line Daryl. I'm sure someone will come along and give the bow a new home.

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

Re: THE 1: 0.625 or 5/8 BOW.

#3 Post by greybeard » Tue Apr 28, 2020 1:23 pm

Pleasing news,

The club member who shot the bow in for me was amazed at the bows performance. With regards to cast he felt that it was not far behind his 60# glass laminated longbow.

Although no actual numbers were produced I will accept his appraisal of the bow.

Another comment worth noting was that the arrows hit on target where the bow was pointed.

After several hundred arrows the bows tiller had not noticeably changed. The bow exhibited a little bump on loosing an arrow which probably indicates that the tiller needs a slight adjustment to suit the archers shooting style.

On close inspection of the belly there was no sign of fretting which was good news as some hardwoods do not like the ‘D’ cross section.

Finally the archer carrying out the testing was so impressed with the overall attributes of the bow that he purchased it.

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

Re: THE 1: 0.625 or 5/8 BOW.

#4 Post by Stickbow Hunter » Wed Apr 29, 2020 9:14 am

Great news all round then. :handgestures-thumbup:

indie
Posts: 101
Joined: Mon Aug 05, 2013 2:44 pm

Re: THE 1: 0.625 or 5/8 BOW.

#5 Post by indie » Wed Apr 29, 2020 7:41 pm

A very interesting bow Daryl, I like it. Removing wood from that and keeping it true to the cross section along the entire length would indeed be a challenge so well done. I'd love to see a photo of it at full draw.

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

Re: THE 1: 0.625 or 5/8 BOW.

#6 Post by greybeard » Fri May 01, 2020 2:17 pm

Jeff, it was good to move the bow along as it was far too heavy in draw weight for me.

Although I did not get quite as much for the bow that I was hoping, I have gained access to billets of red ash and what appears to be Austromyrtus bidwillii.

I believe this was quite a good move as there is a limited market for the style of bow involved and not having laying on the rack hoping for a buyer sometime in the future.

Indi, the concave scrapers and a long sanding stick help to maintain the profile.

I don’t have any pictures of the bow at full draw but I may be able to get some in a couple of weeks.

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!....

Post Reply