Problem with roasted ash

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by Andy C, Feb 4, 2019.

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  1. Andy C

    Andy C Member

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    A couple of months ago (Oct./Nov.) I bought some blanks for guitars and basses.
    I had the idea of maybe trying something different so I decided to get a body blank of two pieces of roasted ash.

    This thing is probably the lightest piece of ash i have ever seen.
    Very nice grain and almost perfectly bookmatched.
    The problems began two weeks ago when I decided to build two P-Basses.
    One with red alder and the other with this roasted ash.
    I started to see the first problems when I hand planed the joints to glue the two pieces together for the body.
    The wood is VERY brittle.
    Small chips are falling off all the time.
    You can't use a thicknesser machine, so I decided to make it thinner only use handtools.
    Luckily I'm very experienced with handplanes so things are a bit better.
    But my concern is for the time when I'll have to route this thing, after that when I'll be making the belly cuts etc...

    I was planning to put a Bosnian maple top on it since I have some very pretty looking pieces and I'd hate it if a maple top gets thrown away as well...
    So I have to find a solution before that.

    Do any of you have any experience and could advice me in to how to continue with this piece of wood?
    I hate to throw it away in case of a failure.
    Also, I should inform you that it's much darker than other roasted pieces I've seen.
    Much darker than what Warmoth has in stock for example.
    I'll try to upload some pics in a couple of hours.
     
  2. B. Howard

    B. Howard Silver Supporting Member

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    Yes, thermally modified wood is brittle. It can also pose problems when gluing. Sharp tools are a must! For routing pickups, etc. consider a down cut bit to minimize chipping.
     
  3. Khromo

    Khromo Supporting Member

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    I recently did some routing for pickup cavities on some roasted ash. I found it a little nerve-wracking to work with at first!

    I had some scrap to experiment on, and it seemed to have a little tear-out baked in there! Not too much, but there were one or two little surprises here and there.

    I decided to use a very sharp blade to scribe the outline of my cavities before routing the final profiles. As Brian suggests, treat yourself to a few new high quality bits and you should be fine.
     
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  4. Terry McInturff

    Terry McInturff 40th Anniversary of guitar building! Gold Supporting Member

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    Yes friend Brian! Down spiral end mill = a must
     
  5. Andy C

    Andy C Member

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    First of all thank you guys for your help.
    I contacted the guy who will make the paint job and also is a very experienced luthier and gave me info on a few shops which sell spiral routing bits here.

    The bits I have now are new and all of them are CMT.
    I haven't used them for more than maybe a couple of bodies and one neck.
    But, I decided to play iit safely and go for the spiral one.
    What should I use for the roundover?
    I mainly use CMT because I can find them in good prices.
    And I also have some Wealden for the tight corners of some neck joints.
    Do you suggest and other brand for a spiral one?

    He also proposed that I might want to leave out of this project the maple top.
    He suggested that if I manage to have only small chips, he could make it look as if it's some kind of a relic body.
    What do you you think about that?
    I had no problem gluing the two pieces, but I have some concerns about adding the maple top.
    I have some beautiful pieces and I 'd hate to waste one of them...
     
  6. Riscchip

    Riscchip Supporting Member

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    Are any of you guys using a top-bearing spiral bit? I've never seen one small enough for pickup cavities--I'd love to find such a thing.
     
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  7. Andy C

    Andy C Member

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  8. Mike9

    Mike9 Supporting Member

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    For the round over try moving your router backwards and not forwards. In other words on the pull and not the push. It'll take lighter passes, but you might pull it off.
     
  9. Tone_Terrific

    Tone_Terrific Supporting Member

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    The grain is nice enough that you might want to emphasize it rather than add maple.
     
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  10. eclecticsynergy

    eclecticsynergy Member

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    If it's turned into ash I think it was roasted too long.
    Sorry, couldn't resist.

    The grain is very pretty; it'd be a shame to lose that. Still, I think a relic look is the simplest answer.
     
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  11. Andy C

    Andy C Member

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    If you liked it, wait till you see the other side where the maple top will be glued (I think...).
    The grain on the top side is much more vivid and much more symmetrical than this.

    The thing is that it's darker than it appears on the photos, so after the finish I'm not shure how much of that will be very visible.
    I said "I think" because I must say though that after you guys suggesting to leave it as is, I'm leaning more and more towards not putting a top on it.
    Of course I also trust the opinion of the guy who will do the paintjob. He's much more experienced than me and has a very good aesthetic taste.

    If I decide to leave it as is, then I think I should start routing it because right now it's just at 38.1/38.2mm thick.

    This photo is from the other P-bass I'm working on right now.
    The maple top is much prettier in reality.
    So, I was looking forward to put one on the roasted ash as well.



    [​IMG]
     
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  12. Laurent Brondel

    Laurent Brondel Supporting Member

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    The extremely dark colour suggests to me that it was "over" torrefied, so yes the wood becomes extremely brittle and any end grain in the router bit path will result in tear out, if not chunks flying out of the work.

    If it was me I would discard that piece.

    Second best option is to flood the whole piece with thin CA prior to finish sanding so that every little stress crack that you can't see gets sealed.
    I would also be very wary of glue and finish adhesion with that level of roasting, epoxy is probably best.

    Be very careful when tightening screws for pickguard, PUP rings etc., it's better to countersink all of them and drill the biggest possible size, otherwise cracks may appears with compression stress from the screws.

    I do speak from experience, if I use torrefied stock at all now, it will be the very lightly roasted kind.

    What roasting at that level does is destroy the integrity of the lignin, which really is the glue holding wood fibres together.
     
  13. Andy C

    Andy C Member

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    I've been thinking the exact same thing today as the parts for the basses arrived.
    Bridge, machine heads, etc... and I started having the same questions.
    How the screws are going to hold, especially if the wood around the neck screws will be strong enough, etc...

    Keep in mind that in person, it's a bit darker.
    The photos are just right after I had sanded one side and hadn't wipped off the dust.
    If you see the other side which I decided to flatten it with a handplane, you'd see that it's darker than the photos I posted here.
    If I could take a closer photo, you'd see that the wood texture from the chips looks almost like coal, but lighter coloured.
    You can barely see any wood fibers in the pieces that have fall off.

    So I decided to play it safe and contacted my supplier in Germany.
    He emailed back telling me that he can send an other piece, free of charge, but a lot lighter roasted this time.

    So for now I'm afraid I'm going to put it aside and wait for the new piece to arrive.
    I don't like to quit, so I guess I will pick it up later sometime when I'll have more free time and give it another try...
    I'll be very sorry if this goes to waste, because it is a beautiful piece of ash.

    I really thank you guys for all your help and suggestions.
     
    Last edited: Feb 6, 2019
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  14. KGWagner

    KGWagner Member

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    Do a little research on "climb cuts". Has to do with the direction of cut, which gets critical on brittle woods. You will undoubtedly end up cutting from more than one direction as you cut the perimeter.
     
  15. walterw

    walterw Gold Supporting Member

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    talk about that a little, please; heavily roasted wood doesn't take glue as well?
     
  16. Laurent Brondel

    Laurent Brondel Supporting Member

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    That is correct, on the over torrefied dark stuff adhesion is weaker with either finish or glue. I had to take off a bridge on a roasted top, and it came off way too easy to make me comfortable, HHG. It held through string tension without issue though.
     
  17. KGWagner

    KGWagner Member

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    I haven't had problem with it simply being torrified, but I wouldn't try to apply a finish after I've burnished it. It's very hard and and ends up sorta "glossy", so it would be kinda like trying to paint glass. Not much for anything to "bite" into. Not that you'd want a finish on it after that, anyway. Feels fantastic. Not like a gloss finish at all.
     
  18. Laurent Brondel

    Laurent Brondel Supporting Member

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    Any finish needs mechanical adhesion on the substrate, so that’s kind of besides the point. Burnish any non torrefied wood and any finish will have a chance to delaminate from the substrate.

    With the dark torrefied stuff I saw a tendency for lacquer, poly or varnish to delaminate when there is a stress riser (in the finish): next to frets on 1-piece necks, corners etc.
     
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