Red Oak and Bamboo recurve

[hunterguy1991]

Evening all ,

After finally getting all the gear together for a crack at a Recurve similar to Greybeards awesome ones I got to start working on it this arvo.

Newzin showed a fair bit of interest in how this bow goes so here we go... I may have got a little carried away at the start and forgot to take a few photos of shaping the Red oak blank before bending. The bow is 66 inches between the nocks, 36mm wide in the limbs, 30mm wide in the handle, 16mm wide at the string nocks. The tips are 7mm thick and this thickness continues 12 inches into the limb from the tips where the width changes. At this change it then goes from 7mm to 10mm in a straight line to the fades where it then goes to full board thickness (19mm).

First shot is of the second tip in my steam box before bending. The tips on this were 7mm thick so I gave them 20 mins steaming. General rule of thumb I've read is one hour steaming for every 25mm thickness of timber. (yes I steam my bows in the kitchen haha )

Bamboo Recurve steaming (640x480).jpg (157.67 KiB) Viewed 3655 times

Second photo is of the second tip in my bending jig... There are many different ways of making jigs for bending but this one is simple and seems to work well.

Bamboo recurve bending (640x480).jpg (167.64 KiB) Viewed 3655 times

Next photo is of the results of steam bending on the red oak blank. The tips came out of the jig within a 16th of an inch of each other so I'm pretty happy with how the bending went.

Bamboo Recurve bent blank (640x480).jpg (152.97 KiB) Viewed 3655 times

Last photo is of the bow all glued up in the jig. Originally I wanted to use some clamps on the tips and strap in the handle and mid limb but I couldn't seem to get enough clamps on to hold the bamboo onto the oak so I continued the strap all the way from the handle to the tips. On inspection I have good glue squeeze out on both sides of the stave all the way to the tip of each limb.

The bow was then put into reflex as Daryl suggested to me and also in his threads. Its about an inch and a half reflex at 12inches in from the tips.

Bamboo Recurve glued in form (640x480).jpg (182.67 KiB) Viewed 3655 times

Not bad for 3 hours work I reckon!! I just hope that it survives now.

Bow will be left to glue until tomorrow lunchtime when it will come out and the edges get cleaned up to show a neat glue line (hopefully!!) Then I will begin tillering very slowly and steadily.

More photos tomorrow.

Colin

[bigbob]

looking good! Be watching with interest

[hunterguy1991]

Cheers Bob!!

[hunterguy1991]

Ok guys, have hit a small snag...

Got the bow out of the form this morning and cleaned up all the excess glue, slightly rounded all the edges to lessen crack/split propagation and have started evening the tiller out with a long string.

Unfortunately I have a little bit of propeller twist happening in both limb tips. Was hoping for some advice on fixing this issue. I know that to remove the twist I need to lose a little timber on the opposite side of the limb to the direction of twist but have also hear that you can fix it by slightly deepening a string nock on one side.

Photo below shows how the limb (ive called this one top for tiller orientation purposes) twists off to the left a bit. Bottom limb also twists off to the left when viewed the same as the top as pictured.

Bamboo recurve limb twist (480x640).jpg (96.13 KiB) Viewed 3624 times

Was wondering which nock to deepen slightly, direction of twist side or opposite side? My engineering mind says to deepen the same side as the twist so it has less eccentricity to the centreline of the bow.( which should mean less twist I think) but I wanted to confirm with someone that has actually done it before as I have not.

As for the tiller itself, its not looking too bad after a little work here and there, but as you can see from the photo, the twist is pretty bad...

Bamboo recurve initial tiller evening (640x480).jpg (161.84 KiB) Viewed 3624 times

String still comes all the way back to touching the handle after drawing so there is no set in the limbs so far.

I would like to remedy the twist issue before I go much further with the limbs... advice is much appreciated.

Colin

[bigbob]

that's correct deepen nock groove on same side as twist or as a last resort remove little from edge mid limb and out toward tip on the other side.

[hunterguy1991]

Cheers Bob!!

I will give it a crack and hopefully get a bit of the twist out of it.

[mikaluger]

i'm watching as I have an unfinished bow on the rack with a similiar problem.............

[greybeard]

Colin, it is a pity about the limb twist but it may be something you can live with.

A couple of things to check;

Was the red oak core true after steaming and was the cross section symmetrical i.e. equal thickness at edges?

Similarly was the bamboo true and have a symmetrical crown?

If both components were true the problem is most likely in your gluing up / rubber strap method.

Daryl.

[Nezwin]

Propeller twist aside, it's looking good! My experience is very limited in that area so I'm afraid I can't weigh in on the advice.

It would seem steam bending is the way to go with Red Oak - my efforts with dry heat (w/ peanut oil) have been unsuccessful but it looks like you've had good results. I'd always thought of Red Oak as unable to withstand the stiffness of a bamboo backing (as opposed to Osage, Spotted Gum, Ironbark, etc) so it's interesting to see someone is having some success in that regard. It's this experimenting in new combinations & ideas that keep me enthusiastic about bow making, I look forward to the finished product!

Neil

Edit: Having just had a think about the propeller twist, I've (almost) always had an issue with flattening bamboo wherein a small lump in the centre of the backing can cause one edge to lift, essentially deepening/thickening the limb at that point. There's a few examples of that on my Blackbutt experiment thread. How did your glue lines come out? Just a thought, though, and I'm sure you've considered this already. As always, best listen to Greybeard

[hunterguy1991]

Hi guys,

Have put this one on hold for the moment, will be away from home until mid next week and been busy with other things all today so no work on it.

Daryl, eventually I will make up a new string for it and continue the process to get it shooting, I want to see if the Oak can handle full draw without failing.
As for the true-ness of components, the red oak was very straight after steaming even though I wasn't as accurate in cutting it out as I should have been (few little minor thin spots.) The bamboo on the other hand most likely was not as good as it should have been. Being the first time ive done the preparation of it for a bow back it probably was not up to a good enough standard (which I will improve upon with the next one.)

And I do think the glue up method may also have had some part in putting a twist in it, will look into it on the next one I try if I should do it the same method. otherwise I will be investing in a ton of clamps.

Neil, glad to see you are enjoying the thread so far. Yes red oak seems a bit of a dark sheep in terms of a timber for bows, but its proving successful for me so far so I will continue using it in projects. Would like to do a straight flat bow with a bamboo backing and see how that turns out at some stage soon as well.

The glue lines were surprisingly even albeit a tiny bit thicker than with milled timber but I think I will need more practice with getting the bamboo nice and flat before gluing. This was my very first go at using it as a backing so I was expecting some pretty dodgy glue lines anyway, but, the backing has not pulled off yet so I must have done alright.

I may try to make a string and get a brace shot this arvo but will see.

Colin

[hunterguy1991]

Ok so I lied, after I wrote my last post I decided to make a string and see what the bow would do... WHAT A SURPRISE THAT WAS!!

Made the string and fitted it, brace came up to 4 inches (bit short but the bows twisted so who cares?), tiller looks ok tho...

Bamboo recurve 4 inch brace (640x480).jpg (172.12 KiB) Viewed 3549 times

Set it on my tiller jig and then pulled a bit... no snaps crackles or pops... pull a bit more... few more and i got it to 26 inches as pictured and I will let you all guess at the draw weight for a bit.

Bamboo recurve at 26 inches (640x480).jpg (118.06 KiB) Viewed 3549 times

Limbs are a tad un even still but at this stage I don't mind too much... I may play around with it and try to get them both the same but with the twist I don't see the point. Left limb is bottom limb in the shot and they may even out with my grip being very slightly low of exactly even both sides of centre but I would need a photo of me shooting it to tell.

Spits an arrow out pretty well tho!!

Last photo is of the bow immediately after shooting it for a dozen or so arrows. There is a little bit of set and the weight did sink while shooting it but it settled into a really good spot for me.

Bamboo recurve after initail shots (640x480).jpg (114.41 KiB) Viewed 3549 times

With it being my first go at a bamboo backed bow and third go at a recurve I'm pretty happy that I just got to shoot it and it didn't break yet.

Colin

[greybeard]

Colin, if the bow does not throw the string at full draw or loose I would not worry about the minor limb twist. Put heaps of arrows through it to see what happens.

.....Second photo is of the second tip in my bending jig...

Is that photo for illustrative purposes only and that the oak blank was full width at the tips before steaming?

Red Oak (Quercus rubra)

Workability: Produces good results with hand and machine tools. Has a moderately high shrinkage value, resulting in mediocre dimensional stability, especially in flat sawn boards. Can react with iron (particularly when wet) and cause staining and discoloration. Responds well to steam bending. Glues, stains, and finishes well.

And to confuse the issue did you actually get Red Oak (Quercus rubra)

Oak Group.jpg (48.72 KiB) Viewed 3542 times

Daryl.

[hunterguy1991]

Daryl, I have just spent the last half hour putting arrows through it with no issue, so I cant really complain..

No the blank was cut to width and then steamed and bent... next time I will leave it full width and steam bend it. its very possible that that's where the twist came in but I inspected it after bending and it did not look at all twisted.

As for the timber, who knows what it actually is! it was purchased at Masters as Red Oak and that's all the info I can give you... it bends will and held up to being used in this bow so I will use it again without question.

The bow settled in at around 60lbs at 28 inches so the Oak(??) can hold up to a fair bit of punishment.

Colin

[greybeard]

Colin, as you have probably realised by now some limb twist need not necessarily be a major issue.

The reason for having the tips full width is that it allows you to create a new centre line if the tips go out of alignment with the handle during the bending process.

It also gives you a safety margin if splinters lift on the edges.

One other point to remember is that when you take the core off the recurving block and there is an alignment / twist issue put the offending limb back into the steamer and it will straighten out, you can then re bend the tip.

When gluing the bamboo to the core I use an adjustable form. By using several posts I can make minor changes to the limb profile.

To keep the components in line I drive 1 ½ “nails into the top of the posts either side of the core, this prevents sideways movement when clamping up.

Determining Reflex.JPG (71.41 KiB) Viewed 3518 times

To help maintain alignment in the tips be sure to have posts about 1” from the tips. ‘F’ clamps are used to pull the bamboo and core down to the intermediate posts.

Small clamps are used between the posts.

Look on the bright side, you have created a bow that shoots, it did not cost much and hopefully you learnt from the experience.

Daryl.