I think you are right. I should not have rushed it.

It is not easy to photograph bit this is catching a light reflection.

Brian.

Yeah its still soft! I would take the tension out immediately, straighten it out/level it out and then post cure with the ideal curing cycle and ramp temps. Then put the strings back on it and see if it worked.

Nothing to lose now really....

Still a shame tho, because it is a beautiful piece! I would have done exactly the same as you. Learning by doing i suppose!

but now we know.

cheers

It was coming together so well that I was scared of overheating and ruining it.
I am not too concerned about the bend as the wooden harp it is copied from bends in the same way.
I may try to straighten it or just build the improvements in to the next one.
Thank you everyone for your comments.

Brian.

definitely needs a bake off in an oven. 

If you can split the part, you can wetlay in some UD carbon to further stiffen it, or even just bond in some Carbon Fibre Strip  or even some Carbon Fibre Box Section to really stiffen things up.  The ideas of making your own moulded inserts to stiffen are also a good idea especially for future instruments.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

To your original question……..adding uni to the flexing side heavier than the opposite side will indeed help against warping. You should do it. However, this now transfers the load downstream to its base. You'll need to strengthen that area as well to provide the most robust outcome or it too will begin to deteriorate.

I have slackened the strings and it has nearly gone back to where it should be. I will clamp it to get it straighter then post cure it.
Thank you all for your help. I will update you on my progress.

Brian.

Hi Brian
Take heart, you have made a beautiful instrument. Don't worry about overheating it. I have taken raw carbon fiber 3k twill and heated it up with a propane torch until it glowed red hot and would glow in the dark. When it cooled it was in perfect condition. Carbon fiber is an amazing material. Just for the fun of it I used a strand of carbon as a piece of wire in an electrical circuit, it conducts electricity very well. So don't be worried about damaging the carbon fiber. Now with your harp you should be able to take it up to 250 f and hold it for 4 hours and it should then be fully cured. Check with the guys you bought the resin from what exactly you can take it too. When its cured do a tap test with a box wrench, (this is very scientific and I use this technic all the time.) It should sound like your tapping a wine bottle.

Another tip. If your neck is not back to where you started. Put on a thick pair of leather gloves and then heat up the whole neck of your harp to a temperature that would be too hot to handle with your bare hands. You will be amazed how you can bend the neck back like bending taffy. Hold it in position or against a straight edge until it cools. (do be sure to keep the heat gun moving so as not to over heat any specific area)
Hope this helps.
Fred
 

    

Update.

I made an oven out of sheets of Kingspan type insulation. Used a fan heater in the bottom with an electronic thermostat. Heated the harp to 40degC for 6 hours, 50degC for 6 hours and 60degC for 12 hours as recommended for the resin. I changed the temperature up a few degrees at a time. I also cooled it down over about 8 hours in stages. This may be overkill but it can't hurt to treat it carefully. Re strung and tuned the harp. There is only a slight curve to it now. This may be where it had not completely straightened.  Also the snakeskin effect on the side under compression has gone.

Thank you all for your advise.

Brian.

Great to hear everything went well, thanks for the update!

Matthieu Libeert
Founder MAT2 Composites X Sports
website: www.mat2composites.com

Good to hear it worked out ok in the end.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant