Urban Luthier

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Posts posted by Urban Luthier


  1. One of the biggest challenges of jointing is getting both edges to mate perfectly. If you do them one at a time, edge up in a vice, there is a tendency to twist to the right on the start of the stroke and twist to the left on the end of the stroke (if you are right handed that is).

    If you are having trouble with the centre joint, one trick is to plane both edges together. That way any irregularity or twist will be canceled out when you place the two edges together for gluing. Joiners have used this workflow for for centuries! 

    other thing to note is to ensure you plane is sharp and the blade is straight (i.e. no camber).

    Once you get it perfect, glue it right away! With a bit of practice it is possible to get a perfect joint. I routinely have to use a 5 x loupe on spruce tops to see where my centre join is.

     


  2. I know this is an old thread but i was wondering if anyone has made a cello off of Sacconi's reconstruction of the cello b-form as posted above. Based on Joe's comments, it appears to differ slightly from Roger's  Davidov drawing (lower part of the centre bouts are lower in the Davidov)


  3. 6 hours ago, jezzupe said:

    boy I'm sure glad I'm not all caught up in this here "measuring stuff" I have a 1-6 with "high" above the 6, so, I turn it onto "high" for about 2 min, then turn it down to 6 then down to 5, and then turn it down between 4 and 5 and whatever that is, it just right! geez next thing you know you guys will be asking questions about rulers and measuring cup's :lol:...

    for those of us who measured the temp i don't thing it is about laser precision here -- most of us did what you did - test a bunch of different  temperatures  based on personal workflow to find out how hot you can bend without burning. Then mark the position on the iron and be done with it. in my case I was simply curious to know if the surface temp of my iron matched what's printed on the dial. And in my case it is pretty close.


  4. 1 hour ago, JohnCockburn said:

    The "free" surface temperature of the iron is only part of the story. What's important is the maximum temperature of the wood during the bending process, which will also depend on technique (eg time taken, amount of water used) and the power of the heating element. 

    Yes exactly -- just because the bending iron is 170 C doesn't mean that is what the wood sees. Factors like Steam and insulations from the bending strap likely increases the temperature the wood sees


  5. I have the Luthier's Bench Iron and I set it to 170 C -- it is fairly accurate +/- 5 C degrees I measured it with one of these.  Bends perfectly at this temp as long as the rib is fully supported by the strap - no stains, burns or discolouration, no kinks or breaks

    I did a bunch of experiments recently and took notes. Keep in mind this is with my wood - medium figured euro maple and my workflow (which I admit is a little slower than ideal)

    • 200-225 degrees -- WAY too hot -- melts the winter growth and creates caramel stains in the forms of dots and streaks. Wood discolours and burns 
    • 180 - works but some slight discolouration of the wood, chance of caramel streaks if you don't work quickly. perhaps useful for highly figured wood
    • 170 - works the best as noted above - slightly moistened rib, light steamed for 10 seconds, establish the curve by pulling slowly around the iron and bend dry for everything else - no burns, discolouration, cracks
    • 150 - Works but need to steam for longer - makes the wood too wet - need to work more slowly - easier to get kinks or breaks even with the rib is fully supported

  6. 7 hours ago, David Beard said:

    How else are you going to twist the neck on the plate pins and end up with assymetric sides and corner locations?

    Somebody already said read Hargrave's acticles. Ditto!

    I'm quite familiar with Roger's articles ;). I Don't see any reason why a modern maker couldn't follow a variation of the  workflow employed by the ancients - in this case the neck is dovetailed to the rib garland rather than nailed to it. Then go about the workflow outlined by Roger in the Guarneri book to scribe the outline. The neck would need a notch of course to accept the top plate


  7. 4 minutes ago, David Burgess said:

    Valid question. My making was sourced largely upon a restoration background, so with a little experience, it was a piece of cake to set a neck into an already completed body assembly. There might be easier and better ways.

    Of course this makes perfect sense David. I should have clarified above -- my curiosity is more around why many schools teach this 'restoration informed' method in new construction, when there may be other workflows for jointing a neck that are easier for students to learn and execute. 

    I just looked at an old trade secret article by Howard Needham that illustrates the method for jointing a neck before the back is attached. I have never done it this way but I think I will give it ago in the future as a learning exercise


  8. 17 minutes ago, Jerry Pasewicz said:

    I believe that is correct.  The definition of a dovetail is pretty general, that is an easy call, but the more specific “tapered sliding dovetail” varies a little bit, but I would not have an objection to that term.

    Thank you as an amateur I've only this a few times but looking back, that is exactly it, a sliding dovetail (albeit one with very oblique side angles)

    Next question is a little harder... for the life of me i cant figure out why modern makers continue to perform the dovetail neck set with the back installed - obviously this workflow makes sense for converting a baroque to modern setup (which is where the the method comes from if I understand correctly) 

    But from a pure woodworking perspective, it is much easier to execute an accurate sliding dovetail joint with the back off as one can see the joint from both ends and verify accuracy as as you go. The added bonus is the neck waste  can be cut flush to the back side of the block.