Magyar Bow

[Edmund Dohnert]

Adam and Paku,

Thanks much for the info and advice.

I will certainly heed this advice and not add any curvature to the bending section prior to attaching horn and sinew. I can now see why that would add difficulties.

I see that a number of the design diagrams for the Magyar bow indicate a 30-degree angle between the siyah and the bending section plus the flat bending section making a 10-to-20 degree forward angle with the grip section. As such, the total angle the nock makes with the horizontal plane (with the bow lying flat) would be 40 to 50 degrees.

Because I had not initially planned on angling the bending section at the grip, as appears to be done with some Magyar bows, I thought that I'd make up for it a little by having a 40-degree siyah angle. If I do need a bridge, I can always add one, but as Paku rightly points out, it would no longer strictly be a Magyar bow.

I know that my nock-to-nock distance of 135 cm is around 10 cm longer than what is indicated for a typical Magyar bow, but I deliberately made the core a little longer, as I was being cautious and wanted to increase the radius of curvature a bit. I can always cut the core, take out a section, and then splice it back together. But perhaps I can make up for the reduced stiffness by going a little heavier with the sinew. (?)

Thanks again.

[paku]

For a 28 inch draw length the best is 130cm overall length (90+2x20) Even a 10 cm longer bow will have a considerable hand shock and reduced cast.

[Edmund Dohnert]

Paku,

So, if my core is 110 cm long in its unreflexed and unbraced state, do you think it advisable for me to shorten it up to somewhere within the 90 -105 cm range that you mentioned? If so, what length would you use if it were your bow? Right now the nock-to-nock distance is about 135 cm. Should I bring that down to a little less than 125 cm?

Mind you, I am not going for a really heavy bow, and something at around 60 lbs would be more than enough for someone my age and size. (My comfortable draw is only 26 inches anyway.)

I could just cut the core at the midpoint, remove the required amount, and then reattach the two limbs with a V-splice. (Or maybe just overlap one limb onto the other, as I've seen in some pictures. Though wouldn't a V-splice be better?)

While I have the core in two pieces, do you think that while I'm at it, I should angle each limb outward to about 10 degree before I rejoin them? As I already have the siyahs at 40 degrees, the additional 10 degrees would bring me up to 50 degees. Or would it be better to just leave the limbs at the current straight 180 degrees, i.e., zero outward angle?

I really appreciate this advice, as it will help me get it right the first time.

[paku]

As it is your first bow I would let the core as it is. It would be very difficult to cut it in the middle reflex and rejoin it as you have already attached the ears. The 135 cm ntn is OK.
The main problem will be the 5mm thickness of the core. You will have a bow (if everything goes well) which will bend mostly close to the handle. I just can cite Adam?s formulation ?the core and the horn have to have an exponential decay? (from the middle of the handle) . This may be an elusive definition but it works perfectly. However thid can not be achieved by 5mm overall thickness of the core.

[Edmund Dohnert]

Paku,

It really wouldn't be all that difficult for me to remove 10 cm and splice the core back together if a 125 cm nock-to-nock distance would be an improvement over my original 135 dimension. I want to do this right.

Just to make sure we're talking about the same thing, when I say that my core is 5 mm thick, I am referring only to the bare wood, not the overall thickness of the completed bending section. So, if I have a 5 mm wooden core, a 4 mm layer of horn, and say a 2 or 3 mm layer of sinew, I would have a limb thickness of 11 to 12 mm, which seems to be typical for a moderate weight bow. Or am I missing something here?

Now I am well aware of how sensitive stiffness is to thickness (varies as the cube), but from what I've seen of these composite bows, there usually isn't much taper in width across the bending section, but there is usually some thinning of the horn as one goes from the grip section to the ears. I assume this is where most of the variation in stiffness comes from. In the Magyar bow, is there typically also much thinning of the wooden core itself as one goes from grip to ear? If so, what should that thickness variation be for a moderate weight bow?

[Edmund Dohnert]

Paku, Adam, et al,

I have digested your advice and other's and thus decided to salvage the ears and start over again with a new core for my Magyar style bow (I say 'style' because I am not trying to faithfully reproduce it with historical accuracy).

I am at a stage now where the maple core is nearing completion, and I am a bit hesitant to shape it any further or to remove any more material until the horn is attached (which I have not yet acquired).

Here are some of the particulars:

- Unbraced nock-to-nock distance of the bare core - 122 cm

- Angle that each ear makes with the core - 10 degree slanting forward

- Distance from nock along the ear to the core - 20.3 cm

- Length of active part of bending limb - approx. 30 - 31 cm

- Width of bending limb - tapers from 40 mm down to about 32 mm

- Thickness of bending limb - approx 9 mm near grip and 7 - 8 mm near ear splice.

- The core has a VERY slight convexity on both side.

- Desired final draw weight - no more than 60 lbs at my short 26-inch draw.

So my question right now is: should I do any more shaping and material removal or should this wait till after the horn is in place?

Second question: I know that estimating the final weight of the bow is a very tricky and uncertain thing with composite bows, but if the horn and core thickness should be about the same and the sinew thickness much less, roughly what should the final core thickness be for a bow in the 60 lb range? Any advice of whether I need more or less width and thickness taper in the core?

Thanks in advance

[paku]

Do not touch the core now. For a 60lb bow 4-4-4mm is enough.

[Edmund Dohnert]

Paku,

Thanks.

I won't continue with any wood removal until I get the horn properly attached to the core. I will also try to get close to having the thickness of sinew, wood, and horn to be about the same.

I noticed that you did not mention any thickness tapering of the wood core, so should I assume one should keep the core in the bending section of the limb at uniform thickness from the fade at the grip to the fade at the ears?

(I just want to be sure, because I can't do anything about the core once it's locked between sinew and horn, except for making minor reductions in width.)

[paku]

The taper will be prepared after the horn is on the core. The taper is small after the initial drop on the sides of the grip.