Jump to content
Maestronet Forums

Jay Higgs' Bench


Jluthier
 Share

Recommended Posts

Nice! Castrating bands have also been recommended. I followed Don Noon's lead and trimmed the wooden pins jaws down such that when they engage the lining-rib interface, the bars of the springs sit over the middle of the lining. This makes them act like a parallel jaw clamp and roughly doubles the pressure. Have had no issues. I love seeing new ways to do the work, so thanks for sharing!

Link to comment
Share on other sites

  • 2 weeks later...

Another method of work:  This is a post mostly for those of us who have not had the advantage of a mentor.  Jointing the top and the back of a violin has always been a frustrating crap shoot for me, requiring several tries before I have a joint I am happy with.  My goal is always to have a joint line with no irregularities or glue visible.  I think I have tried everything imaginable, and ironically what I have "discovered"  is probably what the experienced and well-taught have been doing for years.  So, for my fellow autodidacts struggling as I have, here is what works for me:  

  1.  You need a plane finely tuned with a very sharp blade set as level with the plane surface as possible.  Guard the blade against even minor trauma which will result in tiny nicks in your wood.  I use a #6 plane.  
  2. clamp the wood in only part of the vice for both planing and rub joint.  Support the other end of the wood as shown in the attached pic, which demonstrates a completed rub joint curing.  This avoids distorting the planing surface by clamping a slightly warped board in a lengthwise vice.  
  3. Plane each piece consistently in the same direction.  Mark each piece so you put it in the vice the same way each time.  If you don't, you may feel a bit of lengthwise rocking of your joint as you try to match the pair; you have created a minimal but important lengthwise dome in one or both of the pieces.  
  4. Visualize the joint line from front, back and through light to test if it is ready for jointing.  Use minimal hand pressure to mate the pieces when you do this.  The line should look nearly invisible from all angles.  
  5. Spot plane for minor high or low spots, especially the common convexity of the center.  Take finer and finer shavings as you do this.  Paul Sellers has a good video on joint planing on the internet.  
  6. When you have a good joint, paint on thin hide glue for sizing.  let it dry, then plane a very fine shaving JUST before you do the actual gluing.  When doing this, I retracted the plane blade fully, then slowly advanced it until the fine shaving was achieved, then 1-3 passes of the plane over the joint.  I use tangential lighting to examine the joint for any last minute defects or debris on the surfaces to be joined.  
  7. For the final joint, the hide glue should should be of the consistency to drip off the brush fairly easily.  Too thin, of course the joint will fail.  Too thick, you will not get a "grab" when you rub the joint.  That is as precise as I can be.  I error on the slightly thick side, and if I don't get a grab, I can thin the glue just a few drops more before re-trying the joint.  
  8. Clamp one piece of the wood the same as before.  Paint hot glue on rapidly.  I have done this with and without heating the wood, and my last satisfactory joint did not use heat.  Rub top piece firmly back and forth until you feel a good "grab."  Once it grabs, carefully make sure the two halves are reasonably aligned; you can force minor shifts if you do this right away after the grab.  If the rub stays slippery and will not grab, this attempt must be aborted.  Take the time to stop, wipe the excess glue off, let it dry, and fine plane it all again.  Use a slightly more dilute glue the next try.  
  9. Once you have a good rub and grab, leave it alone for at least 12, preferably 24 hours before manipulating it.  THEN you can check it out.  The close up of wood is part of spruce I just joined using this method.  I am happy with that.  

What did NOT work for me: 

-fine sanding or scraping the joint to remove burs; joint line actually looked worse.  

- doing a rub joint without sizing the wood

-clamping the joint after rubbing; I know some very good luthiers do this, but try as I may with multiple combinations of clamps, pressures, alignment boards, etc, it was always a gamble whether my joint would be acceptable. 

-trying to immediately  redo a joint after failure; you have to leet it dry and replane it

-accepting a rub joint that does not "grab". 

-sampling a freshly grabbed joint with a chisel to see if it looks good; this just disturbs the joint

-using a table top electric jointer; it got close but not perfect no matter how fine I adjusted it.  It might be OK to use this as a start in very rough wood.  

-doing final planing one day and gluing the next.  This allows the wood to change shape overnight.  I you need a break, take it after sizing and before final planing.  

 

 

Picture1.jpg

153C89D9-C04A-4ADC-9D50-A2525D57BDFD_1_105_c.jpeg

Link to comment
Share on other sites

  • 3 months later...

For those interested in the Mag-ic Probe,  attached is a scatter plot of my own correlations with a mechanical thickness gage using the small cylinder magnet.  This roughly corresponds to what David Burgess reported some time ago.  The line is what a perfect correlation would be.  image.thumb.png.02a969a018ccab14e099ac14e5726d42.png

Link to comment
Share on other sites

  • 3 weeks later...

Another method of work.  Those of you who can cut a purfling groove in your sleep don't need this crutch, but it helped me.   As above, I struggle with purfling.  Especially on the top cutting through spring wood without splintering it is a challenge, even after sizing with hide glue.  I usually end up with some gaps that I know won't fill in during the gluing process.  I like Roger Hargrave's method and use that, though it hasn't yet saved me from some rough looking corner joints.  As a modification of this method, I made a "purfling clamp" to force the groove to swell inward when flooding the purfling with boiling water.  This appears to have worked, though I am sure major gaps would not fill in and of course bad points and B stings are not improved.  Attached is the clamp and the top I glued with it. The C clamp keeps the top from riding up.  Rubber bands apply the clamping force.  This top turned out better than my first one.   My points and bee stings still need work:  I cut the C-Bout purfling slightly short and the outside groove at the corners was too wide.  Caveats:  the cleats can dent soft top wood; this happened in two spots but puffed back out with a dash of water.  Will the purfling split after the clamp is removed?  Not yet, but I don't know about the long term.  The jig is fairly easy to use; just use the C clamp to center the top, set in the cleats, then apply rubber bands in any direction that seems to fill the gaps.  Once clamped, I apply hot water as described by Roger.  Note the cleats can go flying, so don't shoot your eye out or that of your bench partner.  The pics are unmodified iPhone pics, except to decrease memory size.  

Purfling2 copy.jpg

Purfling1 copy.jpg

Purfling3.jpg

Edited by Jluthier
added close up pic
Link to comment
Share on other sites

1 hour ago, Jluthier said:

Jackson:  You make a very good point (sic). Yours is what I am aiming for.  I hope to get there eventually.   I like the darker center wood.  Is it commercial or did you make it?  Do you glue in like Hargrave or traditionally?  Thanks, --J

Thanks! This is actually commercial, from Rauch Tonewood. It's maple blacks and pear center. Nice stuff, good price. I use this for when I want to be sure the purfling is very crisp and uniform. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.


×
×
  • Create New...