Official Luthiers Forum!

Hi there,

My first post here. I am building my fourth guitar, Nick lucas style in euro spruce and cuban mahogany. The cuban is reclaimed from 1800's furniture and both sides broke in a fox style bender. I am being helped by a more experienced luthier but we cant understand why it cracked, it was thinned to around 2mm and bent at a little over 100 degrees C after a slight spray with water. The supplier I got it from wondered if it was anything to do with the age of the wood? Wondering if anyone has any advice before i try to bend another set.

thanks all.

I'm sure you will get better advice from the more experienced here, but..... 100c sounds mighty low to me. I set my temp setup at 150c and start bending at 120c.

But you say you were working with an experienced fellow so I just don't have a clue.

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Joe Beaver
Maker of Sawdust

Seems way too low to me as well. I start bending the lower bout around 110C, upper bout at 121C, and waist between 140 and 160C. I'll be bending some Cuban this afternoon, so I'll let you know how it goes.


Ken Jones
Mountain Song Guitars

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Mountain Song Guitars www.mountainsongguitars.com

Sorry, yes, it was 110deg C, i couldnt remember fully. Only have one temperature probe, mabe I'll try several at different points. How much moisture do you guys use. Thanks for the responses.

I agree that your bending temp was too low. But I have found that very, very old wood can be more brittle than that of the same species that was recently cut. Your old mahogany sounds very nice, quite possibly S. mahogani (Cuban or Santo Domingo mahogany). It may be worth getting some Super Soft 2 to bend the next batch. It would be a shame to crack more of your special wood.

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Stay with the happy people.
--Reynolds Large

Thanks all, it was certainly cuban, pink and slightly ribbonny and much denser than Hond.

Just to clarify as my friend and teacher was watching the temp whilst I did the bend, we bent at 110 when we bent the lower bout, upper bout at 115 and waist about 125. We then cooked it for five minutes but i expect the damage was done when bending. I cant find any supplier for super soft in the UK.

I have some old reclaimed Honduran Mahogany from old church pews. I have found that some of it will simply not bend without cracking, even with super soft. Then other pieces bend with no problem. All of theses pieces are well quartered. So, to me it seems that it all depends on the grain structure. Not visible to the naked eye.

Chuck

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Your temp does seem low to me as well. I generally start bending around 120 and by the time I've finished with the waist the temp is generally around 150. I do place a piece of wet kraft paper on either side of the piece I'm bending, and wait for it to start steaming off (around 120) before I begin bending the lower bout. I haven't bent Cuban, but have done a couple of other species of Hog with no problem, although the wood I've used was not old.

PM sent about SSII if you want it.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

I didn't catch this the first time I read it but it appears you bent the waist last? That puts the wood in fairly major tension and depending on how tight your waist is (the guitar, that is!) it could certainly be enough to tear the wood apart. I bend the waist first, then lower bout, then upper. Bending the waist first is standard operating procedure so far as I know.

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Stay with the happy people.
--Reynolds Large

+1 almost.
I part bend the waist first, (leaving it maybe 1/4" from fully bent), then lower bout, top bout, and then gently the last part of the waist.
Leave 5 minute on max temp, cool for 1 hour, then up to full bending temp again for 5 minutes, leave overnight.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Sorry, should have been MUCH more specific, waist down partway first, cook for five mins and then leave to cool then into mould. Thanks for all the experienced replies, this is great. Got some super soft on the way now too!

Have you found a source in the UK for SSII?