Lemonwood stability

[Nezwin]

Has anyone had any experience with instability in Lemonwood/Degame?

I recently purchase a 140mm x 45mm board and ripped a 1.25" length off of one edge. Using the 45mm edge as a back of the bow, I proceeded to mark a centreline, etc, and cut to shape. Coming back a few days later I've found the timber has warped considerably. I've clamped it to the bench now to try & 'force' it straight again but I believe I'm onto a loser with that approach. My mistake, I think (and please, please correct me), was to use the 45mm edge (ie, the depth/thickness of the board) as the back - the back instead should of have been from the 140mm face of the board (ie, the width of the board).

Has anyone had a similar problem occur with lemonwood or any other timbers? I was under the impression this was one of the more stable timbers around, so I'm considerably surprised it has warped so much.

[hunterguy1991]

Cutting thin lams off big boards is always an issue mate, because the larger board still has so much residual stress left in it from when it was a tree there is a lot let go when you cut a smaller lam from it.

I often get a bit of movement from the Lemonwood I use for bows especially from thick boards...

What kind of bow were you looking to get from it?

Colin

[greybeard]

As a matter of practise I cut timber oversize and leave it in the workshop for about one week if needed hoping that it will stabilized in that time.

If after sitting the timber has taken on a bit of a bend I use a straight edge to mark out a rectangular area where the plan of the bow will eventually be plotted.

I then trim off the excess and let the timber sit until there is no evidence of any more movement.

Although this procedure can be inconvenient the timber should be stable when making the bow.

Daryl.

[Nezwin]

Thanks for the quick responses.

What kind of bow were you looking to get from it?

I was looking to replicate the design I use for Red Oak board bows - a comparison between the two timbers in a design I knew would work. The biggest difference being that the 1" depth measurement on the handle was increased to 1.25" to save the need to add any additional timber.

Red Oak Board Bow Plan.jpg (72.84 KiB) Viewed 4401 times

Red Oak Board Bow Profile.jpg (25.04 KiB) Viewed 4401 times

With the bow 1.5" at it's widest point, I felt that 45mm should easily & safely accommodate that. I ended up narrowing the bow to 1.25" at it's widest point after the first warping (new centreline, etc etc), then it bowed again. I've clamped it and will see what happens - at the very worst, I'll still be able to cut the riser off and use it in a trilam or similar. Likewise, the offcuts from the thickness taper can be ground to short lams or spliced into a very short bow, probably a recurve. Shame to see so much Lemonwood go to waste though.

... I use a straight edge to mark out a rectangular area where the plan of the bow will eventually be plotted.

I do the same, using a piece of aluminium flat, 40mm wide, so that both edges can be used for reference measurements. I also tend to put laminate bows through the thickness sander to ensure they're square post-glue up and before cutting the width tapers.

As a matter of practise I cut timber oversize and leave it in the workshop for about one week if needed hoping that it will stabilized in that time.

In retrospect, this would have been the best course of action. From warm & humid SEQ to hot & dry Northern Riverina is quite a climate shock. I've got two more boards here and the rest of the board I've started with, it'll be weeks before I get back to any bow making things, so they should be stabilised by that time.

[Hamish]

Yep, Had the same trouble with lemonwood. I pretty much do what Darryl does.

Any of these dense tropical timbers especially in thick sections, and have been kiln dried can hold a lot of stresses, or have a difference in moisture content from the inside of the board compared with the outside.
I had the same trouble with a thick, perfectly straight grained board of beefwood(Masssaranduba). The section was square and straight, I laid out the centreline, cut out to shape and one tip instantly warped about 3/8"-1/2 off to the side, Grrrr.

On bows with a handle thinner than the limbs, I always leave it wider than the finished bow, at least until full brace height is reached. This way if the string doesn't line up at the arrow pass you can take wood off the side of the handle to improve string alignment.

Darryl must have got some really good lemonwood for his first experiments(he is also an excellent bowyer). From memory his bows had minimal stringfollow. The couple of selfbows of lemonwood I have made took about 2.5" set, despite never being strained over target weight. All my tropical hardwood bows are laminated, have 1-2" of reflex, backed with hickory. Seems to be a pretty good combo for performance. Laminating also seems to help stop the tendency to warp sideways.

I do really like lemonwood, it instils a lot of confidence in me. It just bends, and bends, without breaking if its straightgrained, but it does take set.

Looking forward to see what you do with your lemonwood.

[hunterguy1991]

I think if you are making unbacked bows from boards, particularly shorter ones 68"ntn and less you should expect some set.

For that reason and to better improve performance i always back the lemonwood i use that comes from boards. I think self bows should always come from split staves for best performance since the natural stress in the timber is best aligned for a bow already.

[Dennis La Varenne]

Neil,

In all my old archery books concerning the use of Lemonwood, one of the remarkable things noted about it was its inherent stability when dry, so I think yours may have been pretty wet perhaps as well as those internal stresses referred to above. However when the old bowyers bought boards to use, ANY SIDE could be used as the back and warping seems not to have ever been an issue.

One of the principle factors from reading the material by contemporary commercial bowyers from the wood-bow period when Lemonwood was used, was selection, and there were clearly TWO types. Highland sourced and lowland sourced. Always preferable was the much denser and harder highland sourced boards or sometimes referred to as 'spars' which may have been large poles of Lemonwood.

Highland sourced wood was obvious from the blue-grey streaking throughout which the lowland stuff did not show. The best Lemonwood bows I have in my collection of old York, Ben Pearson, Outdoor Sports Mfg, Stemmler and Indian Archery bows shows this discolouration and these bows rarely have more than 1.5 inches of set after all these years. The very best of these makers without doubt was York in terms of bow performance and wood quality when I shoot any of them.

Another maker - American Archery Co made very fancy looking bows which have arguably the best fit and finish of all the commercial bows from this period, but almost all have 2 inches of set and more and are a light buttery colour without any of the blue-grey streaking. Their bows do not seem to have the springiness of those of the above 5 makers.

The previous 5 commercial makers seem to have been able or willing or both to obtain the better quality stuff and had the experience to be able to select the stuff when the latter did not.

What we are able to get over here may not be of the same quality as that which was available in the US prior to the Castro regime and the prohibition against Cuban imports where the best quality Lemonwood came from.

Our timber merchants may in fact be obtaining the most easily obtainable from the lowlands perhaps, and hence your problems.

So far as your stave is concerned, it has taken a cast or sideways bend to your intended layout. What about using the original board face side of your stave (if it is still squared and not shaped) as a reflexed back perhaps if I understand your problem correctly.

[Nezwin]

Thanks everyone for the feedback.

Lemonwood wobble.jpg (63.44 KiB) Viewed 4337 times

You can see the original centreline veer off to the left and the second centreline not far right of it. Fair bit of wobble there, I may just give it a bit more time clamped and see if it's easily straightened, perhaps even with a little heat.

Dennis, I think you are right re:Highland/Lowland Degame, and this could well be the lowland species. It's also worth bearing in mind that this is also Peruvian Degame, so perhaps no more a relative to Cuban Degame than Argentinian Osage Orange is to the North American species. I'd be interested to know.

The initial pieces Greybeard was able to obtain were pallets left in the sun for months, or years. This could have given them ample time to season properly, while the dressed boards for sale could be still somewhat green, or given their larger size, contain internal stresses from the kiln. I've got a couple of lengths of the pallet timber, so I might finally tidy that up, ready for working, at some point.

While I was up in Brisbane, I popped into see a fella in Woodford and he showed me a new way to prepare bamboo backings. Gave it a go this afternoon and it's come up well, so I might just have to make a boo-backed version sometime soon... The dressed boards will have plenty of time on the shelf to acclimatise before being used.

[Dennis La Varenne]

Neil,

I see what you mean about the warping. It is a very shallow 'S' shape.

However, if this was a split stave, I would not even give that amount of bend a second thought so long as a string line from tip to tip passed through the handle pretty close to the centre of the stave's width and length. The S-bend looks to be pretty even above and below the handle area, so the limbs would track true to the string thrust.

I have made most of my early split stave ELBs with the same kind of lateral bending in them and so long as the string line lays close to the middle of the stave, they shoot fine with not the least tendency to want to twist in the hand or recoil.

However, when your draw your width template onto the stave's back, you have to mark the widths of your template at say, 3 or 4 inch intervals along the stave and at 90 degrees across your drawn centreline, then join the dots on each side. That way, this bow will have the same template shape as your drawing above albeit with a bit of an S-(character) bend to its back-belly profile. The problem is easily got around that way.

As you say, leave it a bit longer because our Riverina summer is almost upon us and a few of our 45 degree day will suck the moisture out of that bit of wood.

If is doesn't straighten as you want, what about applying a backing wide enough to allow for the lateral snaking, trim the excess off the sides and continue as usual?

Below, I have drawn a red string-line through your stave from tip to tip. That amount of snaking won't be a shooting problem at all and where the line passes through the middle of your stave looks to me to be pretty close to the width centre of the handle area.

Neil's Lemonwood stave.jpg (154 KiB) Viewed 4334 times

The next pic is a visual explanation of what I do myself. I hope it makes sense.

Marked out snakey stave.jpg (167.66 KiB) Viewed 4329 times

[yeoman]

I would be happy to make/shoot a bow hat has that much lateral deviation. In fact, you're in the unique position of being able to extract a character stave from a board! Much worse than bending is twisting...and you con't seem to have any of that.

When I was talking to this vendor, he told me he sourced the timber himself from Peru. The scientific name he quoted me is the same as the Cuban: Calycophyllum candidissimum. So the variation in properties probably has far more to do with growing condition that genetic deviation (in this instance). Similar to differences discussed with respect to Spotted Gum on here previously.

Keep it up, Nezin, looking forward to seeing it done!

[hunterguy1991]

Bit of a snake in it there but as long as the tips and handle are in a straight line she should be right

Glad I spurred you on with the boo backings mate! Looking forward to seeing your first crack at a boo backed ELB with that template we spoke about

Colin

[Nezwin]

I was looking at an Osage stave earlier with the same 'wobble' and figured I'd end up doing just what's described, building bows from boards can get you so used to straight lines & clinical precision.

Onto the tillering tree next, might just narrow handle for a more traditional style.