Laminated Bow info.

[hunterguy1991]

You'd have to contact the manufacturer of the flooring to get that info... but I'd imagine it would be some form of epoxy...

[longbow steve]

The quality Peerless bamboo flooring from Bamboo oz is glued with Urac (urea formaldehyde) which is fine for re heating or heat treating. Steve

[GrahameA]

Hi Steve.

What causes the chrystalisation of the glue? Age or these temperature extremes? Steve

There are a few different types of epoxy and there is uncured epoxy resins and cured epoxy so we need to consider what we are taking about.

My understanding of Epoxy - which is not that good nor that much - is that Epoxy can be considered to be a Super Cooled Liquid, like glass.

The crystal formation is accelerated by a) elevated temperatures, b) temperature cycling. If you want to slow it down then I would suggest that not subjecting the material to heating-cooling cycles and not subjecting the material to elevated temperatures.

Take Note Crystallisation does not occur in five minutes it takes some time - years. I will repeat that, Crystallisation does not occur in five minutes it takes some time - years.

Liquid Resin does suffer from Crystallisation whilst in storage however good production/storage technique/regime would suggest that using 'old' expoxy to glue up bows is not a wise move.

[Stickbow Hunter]

Liquid Resin does suffer from Crystallisation whilst in storage however good production/storage technique/regime would suggest that using 'old' expoxy to glue up bows is not a wise move.

Absolutely correct Grahame. Don't ask how I know.

Jeff

[hunterguy1991]

Jeff, how do you know??

....had to ask/be a smart ****...

[Stickbow Hunter]

Jeff, how do you know??

....had to ask/be a smart ****...

Jeff

[hunterguy1991]

I've stated working on plans for a for but have run into a few issues.

I have settled on a design similar to the one Daryl posted earlier (utilising a series of clamps). Now I know I need to have form the width of the limb but haven't managed to find any timber in Bunnings that thick.

My idea was to screw 2 boards together to make up the 1 and 3/4 inch thickness. What does everyone else do/use to make their forms?

Secondly, in the case of a recurve bow, what are some critical design features. ie, angle of the fades with respect to the longitudinal axis, distance from centre to the shelf etc that I should be looking for.

Id like to use the old Hoyt Pro Hunter I have as a basis for my design (similar to Daryl use of a Black Widow) and was curious as to what I should measure to get a good reference.

Colin

[bigbob]

Regarding form material I use ply glued and screwed together to obtain the desired thickness. Sometimes it may be necessary to utilise different thicknesses to get the desired thickness.

[rodlonq]

I know some don't like it but I have done a fair bit of pattern making for rotomoulding jigs with MDF and that's what I use for my forms. It is fairly stable to temperature application and easy to machine to any desired shape. It seems to be very stable to me. I use the kitchen variety with some moisture resistance and it seem good enough to make the next form from. I wouldn't use solid timber as you are just asking for it to warp with uneven moisture content when the heating is applied and/or rapid changes in humidity. I have read a lot about fellas using laminated vertical beams (structural timbers) for forms, I think that would be preferable to a large slab of natural timber.

Just ramblings, but all the best with your bow building endeavours.

Cheers…. Rod

[hunterguy1991]

Cheers for your thoughts Rod

I think I'll have a crack with ply wood first and see how that goes.

After I get my hands on a bandsaw cutting the form should be relatively straight forward and then I can get on to making a few bows. Have to acquire a heap of clamps also, thinking roughly 20 should get a decent even pressure over the limbs.

Colin

[rodlonq]

Sorry, the question has probably already been asked but where are you located Colin. You are most welcome to use my bandsaw and other gear to get you going if you are anywhere near Townsville (same goes for any of you prospective bow makers out there near Townsville => by appointment only.. ).

As Jeff would say "it would help if you put your location in your profile"

cheers…… Rod

[hunterguy1991]

Would be a bit of a hike up there mate, but cheers for the offer anyways.

Im in Woodford, between the sunshine coast and Brisbane.

I'll be getting a saw after Christmas, so that will give me time to get everything else I need to get started. How long does it usually take to get glass from Binghams? I imagine it would be worth getting glass for a few bows in one hit rather than just one.

[hunterguy1991]

I've been looking through the Binghams site and came across a table of limb thicknesses related to a corresponding draw weights. (called bow draw weight chart). Is this the timber core thickness or the entire thickness including glass??

Colin

[greybeard]

Secondly, in the case of a recurve bow, what are some critical design features. ie, angle of the fades with respect to the longitudinal axis, distance from centre to the shelf etc that I should be looking for.
Id like to use the old Hoyt Pro Hunter I have as a basis for my design (similar to Daryl use of a Black Widow) and was curious as to what I should measure to get a good reference.Colin

I would suggest using the Hoyt as a template because all the angles, limb length etc. is already worked out for you.

When making your form pull the recurve tips in by about 1/2" as a little bit of the curve pulls out when the bow comes off the form.

I think I'll have a crack with ply wood first and see how that goes.
After I get my hands on a bandsaw cutting the form should be relatively straight forward and then I can get on to making a few bows. Have to acquire a heap of clamps also, thinking roughly 20 should get a decent even pressure over the limbs.Colin

The 455mm x 2400 sheets of MDF from Bunning's are reasonably priced and available in 6,12 and 16 mm thickness. I have found it is a lot easier to work with than plywood.

Clamp spacing around 2 1/2" seems ok and you will need pressure strips to eliminate depressions caused by the clamps.

How long does it usually take to get glass from Binghams? I imagine it would be worth getting glass for a few bows in one hit rather than just one.

Generally five to seven days. Purchasing all your glass requirements in one order will save you on postage and handling.

I've been looking through the Binghams site and came across a table of limb thicknesses related to a corresponding draw weights. (called bow draw weight chart). Is this the timber core thickness or the entire thickness including glass??Colin

I am not sure but I believe the chart refers to total limb thickness, however remember these figures are based on the Bingham designs. You could email Bingham's for clarification.

Daryl.

[Goatchaser]

Yes they do refer to the whole limb stack including the glass.

[hunterguy1991]

Thanks for the info Daryl.

The Hoyt has a parallel laminated riser so I could also measure the angle of the fades to the long axis of the bow based off one of the glue lines. The bottom limb has a failure at the fade, but I imagine the limb fade angle is the same top an bottom as is the limb curve profile so I should be able to replicate the top and use as the bottom if I cant trace the entire back profile in one go. Or perhaps just clamp the weak spot and use the bottom curve as is. It seems to go back to the original shape when squeeze between fingers anyway.

I will check the dimensions of the Hoyt as far as width goes shortly and base my form width on that.

I remember you saying you used some high density rubber as a pressure strip (may be mistaken...) where can that be purchased or are there alternatives? maybe a thicker timber veneer the whole length?

That's very quick!! I thought maybe a few weeks as its coming from the states. very good news!!

If I was to use 0.040 glass as a first trial and the bow came in under desired weight by a small amount (5lbs or so), would it be better to increase the timber core thickness or the glass thickness to get the right weight?

If I was to try for a 50lb bow would 0.040 or 0.043 glass be a better choice?

sorry about all the questions in this one..

Colin

[Goatchaser]

Different wait times for different times of the year also, with my latest order I have been waiting for 2 weeks so far.

[greybeard]

Colin, I obtained the high density rubber from Clark Rubber. It is available in various widths and thicknesses and it is sold by the metre.

You could use your form to laminate some thin strips of timber to the profile of the limbs and then use them between the rubber and the clamps.

Stay with the .040” glass and adjust the core.

Daryl.

[hunterguy1991]

cheers Daryl,

I'm pretty sure there is a Clarke rubber close to home so will have a look and try to pick some up.

I thought it would be better to increase the core thickness but wanted to double check.

As far as an initial thickness for my first go at this bow, would it be best to measure the core thickness in the Hoyt and make my core the same and then adjust in the second attempt should it be over or under weight? The core laminations are parallel in the Hoyt so I think I'll do the same with my attempt and see where it goes. I imagine that the properties of the material in the core (probably action-boo) will change the weight if they are different to the material used in the Hoyt?

If I use parallel lams it will allow me to have a crack at making it as soon as I get my bandsaw as I wont need to have master tapers etc.

Colin

[greybeard]

I imagine that the properties of the material in the core (probably action-boo) will change the weight if they are different to the material used in the Hoyt? Colin

I think you will find it has more to do with performance properties than draw weight, different core materials can have different recovery rates.

If I use parallel lams it will allow me to have a crack at making it as soon as I get my bandsaw as I wont need to have master tapers etc. Colin

Maybe, but you will still need an accurate method to sand out the teeth marks left by the saw blade, the laminations will not come out of the saw 'dead true'.

Daryl.

[greybeard]

Hi Colin,

There are some interesting photos in the following link, in particular the bad and good fadeouts.

Daryl.


http://tradgang.com/noncgi/ultimatebb.p ... 0;t=000107

[hunterguy1991]

Thanks for that link Daryl,

I immediately picked up the "bad" fade going through the photos. Definitely some helpful picks as far as building a for goes tho.

Will be sure to feather my fades properly on the first attempt.

Colin

[hunterguy1991]

Gday guys,

Im getting closer to obtaining a bandsaw that I need for making bows. I have settled on one that Daryl recommended and will be purchasing it early in the new year. this will aid in cutting rough laminations and risers etc.

As far as grinding laminations goes, which would be the better option, A grinder mounted as Daryl has suggested in previous posts in this thread (see the pictures) or a thicknesser? Or potentially even a spindle sander?

There is little price difference in the 2 so I'm wondering which would be the better option. I'm aware that the grinder will leave the lams pretty much ready to glue where as the thicknesser would require a rough sand on the surface to help the glue adhere. I feel that the thicknesser would be the more accurate option but wanted some of your thoughts.

Straight Shooting,

Colin

[longbow steve]

Hi Colin, A thicknesser wont really be suitable as you require a key for the glue to adhere to and for doing fine work the thicknesser will just destroy the lamination when it gets to thin (not to mention it may be impossible to do a taper.
A spindle sander can work on a small scale but the abrasive tube will over heat and dull pretty quickly. The setup Daryl has is probably the cheapest option in the long run. Steve

[greybeard]

Colin, I am with Steve on this one.

I believe the basic planner/thicknesser is far too aggressive for this particular type of work. I would even have doubts about the expensive spiral cutter head models.

Controlling the feed rate and lateral movement could be an issue as well as the practical application of tapering laminations. I have seen videos of overhead drum sanders being used successfully.

The thicknesser lacks in flexibility to do other tasks such as preparing fade outs and shaping risers.

Daryl.

[bigbob]

The overhead drum sander as Daryl suggests is used quite a bit and usually in conjunction with a 'sled' that the taper is placed on as the cheaper models won't work under 6mm in thickness so the sled is used to increase the thickness of the lam to allow the work.