Violin Forum/Message Board

[bulerias1981]

I haven't got anywhere with the maple jointing yet. I tried a little bit again with no sucess. I have concluded that maybe its related to sharpness. The blade FEELS sharp, but the finest grit stone I'm using is 650 or so. So I am buying some finer stones. I have concluded this for a couple of reasons. One is, obviously I'm not joining correctly yet. Not getting the edges to meet perfectly. And two, I have to use a lot of downward and foward pressure to make a cut, even on the finest setting. So this is why I believe I need to sharpen with a finer grit, and even hit it with a strop.
_________________
"I only write the notes as written, it is god that creates the music." J.S. Bach

[jessupe goldastini]

if this is the only real problem our having, you may wish to take several tops and backs to a cabinet maker and have them run on the jointer....you could do several in about a half hour, a nice guy would charge you 20 bucks..it will make for perfect seems....or just do what i do.....cheat.....either use one peice or purfling up the center seem....now even if i get a good joint i like the purfeld center seem, i like the look, but i'm sure its not considerd kosher

[Jack H.]

Forget about the strop.
If you use an 8000 grit ceramic stone the strop will just ruin it.

[jethro]

I have been hacking away at the joining problem......
have been doing tops-they plane easily. I had a back to do so I tried
that. Here is what I did...
hand planned the back faces dead flat.
ran through elecctric jointer -- just to help establish 90 degree at joint.
Adjusted hand plane to cut the see through shaving. Made about 5 cuts
like this from ene to end trying to keep pressure on plane even the whole
way. Then reised blade to give lighter cut- about 2 swipes each plate.
Put them up to floodlight. allmost perfect- manualy touched up with plane
untill FLAT and no light across whole length. (about 1 hour work so far..)
Heated joints to about 150 F. Quickly slopped on glue and rubbed about
4 strokes about 1 inch long each and centered surfaces and backed off.
I watched the joint....... after about 20-30 secconds -as I watched--
the ends started to open up- I could see light through them about 2 inches
inboard with flashlight !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

My joint was PERFECT !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I grabbed plate and removed it and wiped it clean on both surfaces.
I a few minuites when dryed out I took the plane and took a SMALLLLLLL
cut off each in about the center 80 percent and tried to make the crack
uniformly fattest in center. Not much - just enough to see some light in
the center. Re heated- reglued.....
THIS TIME..... it felt different !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
I put them together and rubbed..... as I rubbed I could feel the sticking
getting harder every few secconds. I could SEE it had stuck initialy
at the ends-the high spots..... after the rubbinnnng stopped the ends
fused... holding pressure on the joint... while over the next 30 secconds
the central "crack" area swelled out to mee each other while the edges
Clamped them inward. And like magic the joint was zippered up all the
way across !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The spruce did not seem to demand the "spring" in the middle but the
hard maple REALLY needed it to work !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I think the end cracks must be due to end effects and the water adsorption and resulting uneven swelling !

How about that !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Tim !!!!!!!!!!!!!!!!!!!

Hope this helps !!!!!!!!!!!!!!!!!

[Dave Chandler]

I seem to be having some success with my 14" "Hercules" jointing the back pieces, especially since paying a lot more attention to the squareness of the cutting edge and resurfacing the sole. But...

Well, I thought I had a really nice joint this week. After cutting out the rough back outline, I began shaping the back, and as I was nearing my 5mm mark around the edges heard a small "pop" and discovered the joint had seperated at the button, about an inch overall, and just enough to see daylight. Didn't realize that it had any spring in it, don't recall any when I put this together, although I did use clamps. So, I took a very sharp pallet knive and tried to take it apart, and was unable to make any headway. Finally I gave it a sharp knock on the bench, and the two halfs seperated very cleanly. Unfortunately, by the time I got the halves planed and ready to glue again, I lost too much wood for this project, so I went ahead glued it back together and saved it for a future, undersized violin. I was surprised how cleanly it seperated. I couldn't force the two halves apart, not with wedges, bending, brute force, etc, but just a good sharp tap on the bench did the trick. Glad I was not using expensive wood this time out.

My problem seems to be that last inch or two on each end of the wood stock. I can get a nice seam except at the ends where I get a small gap about 1 to 1.5 inches from the ends of the lumber. Usually, its outside the pattern, so no problem, it gets cut off anyway. Maybe I should be adding some sort of splint down the middle between the two halfs extending my working surface area by several inches off the end of the blanks.
_________________
Dave in the Blue Ridge
Southern Violin Association

"Success is the ability to go from one failure to the next with no loss of enthusiasm" Winston Churchill

"I took the road less travelled, and now I don't know where I am." Marco Polo

[violinarius]

Try this next time you do a joint, heat it first, then joint it, and then see how much movement you get.

We were taught in wood working class that 'wood always moves', and it would seem to me that your wood may not have been at equilibrium with the surrounding environment.

When you do one of these joints, you glue them up pretty fast to avoid this movement.

[bulerias1981]

I read in a woodworker magazine that if the joint breaks cleanly even, the fault can be appointed to the glue failing. Perhaps it was too light or too thin of a mixture. If the halves break apart and the wood fractures, then the glue should be ruled out for the weakest link.
_________________
"I only write the notes as written, it is god that creates the music." J.S. Bach

[Jeffrey Holmes]

[Michael Darnton]

I did a demo for the Guild of American Luthiers convention one year where I brought a small case of tops, and joined them all in 30 minutes. The only tricks I know are to have a perfectly tuned and adjusted plane, to stand so that your forearm moves like a piston perfectly in line over the wood directly behind the handle of the plane, and to use the leading, left hand, fingers under the plane (thumb on top pressing down--don't use the ball handle) as a fence to make sure the center of the blade is centered precisely and constantly on the wood for the full length of the stroke.

If you do this, and you set the blade for the absolute minimum cut, about 20 strokes of the plane will result in a perfectly flat, non-twisted surface, with a slight about of spring. You don't have to think at all--just let the plane do what planes do WHEN THEY'RE PROPERLY SET UP AND GUIDED!

I subsequently tried this with a 14-year old nephew with no manual skills or experience, and he took about 15 minutes for his first joint.

The place I see people failing the most when I watch is that they don't get a good stable, machine-like stroke going with the plane, in a straight line, on the same part of the blade. They sort of wobble the plane from end to end, and then are surprised when it doesn't work.

[KenN]

I just had the same problem Dave had the other day. I was fitting the pegs and carving the pegbox a little deeper, and for some dumb reason I tapped the fingerboard on my knee to get the chips out! I heard a funny noise and the body didn't ring anymore. The back came loose on one side from the button to the middle of the c bout. It almost seems like the glue didn't sink into the wood at all. What's the best method to be sure the glue bonds to the wood and not just lays between it? I heated the wood with a heat gun, glued about 2-3 inches at a time, held it together and then clamped it (not too tight, I've been there before!), and moved on down the break. I need a semester long class: glueing 101. In the woodworking errors can be hidden, errors in glueing can't. Is the glue too thick? I had my best luck with glue that seemed thin. I use a small amount of glue at a time and I think it may get too thick as I go along. Maybe I need to splurge more on the glue and just throw it away when (not if) it gets mold on it.

[jethro]

Take heart Dave... If I can do it .. anyone can !
I have to say..... Jeffrey's advice was RIGHT ON TARGET about a little
spring in the middle of the plate. My last experiment where I WATCHED
the edges move appart prooves it. They mooved appart because the
center was absorbing more water (or faster) than the edges and the
caused a swelled "hump" in the center - which causes the plates to move appart- but the last inch or 2 aern't swelling quite as fast or as much so
a crack forms there. By taking extra material off the center- just a
little- you are accounting for that uneven swelling before it happens.
The first part of the joint to "stick" are those very same 1-2 inches at
the ends. They stick in about 5 secconds, and then over the next 30 sec.
the center portion swells MORE and those faces slowly swell out to meet
each other and then THEY also "stick". You don't have to clamp it because those end portions stick hard enough that they apply force
once the center part comes under tension from it's swelling !

When I did it the first time and SAW the thing swelling and the end gaps
form--- I understood what to do instantly. !!!!!!!!!!!
Perhaps I didn't explain what I saw clearly enough the first time.

Please don't take me wronge...... I just threw the "sawn joint" thing
out there to see if anyone had heard of it. (Strobel mentions it but
doesn't talk about it)

I have to say I allways agreed with Michael's and Jeffrey's thinking that
a 10000% PERFECT rubbed joint that is completely invisible in the
finnished product is an absolute must have if you want a top quality
product. ( that's why I didn't give up !!!!!!!!) My Daddy allways told
me to learn from other's mistakes AND their wisdom as well !

Dave-Hope this helps----
PS again make sure your plane sole is FLAT and your blade is VVVERRRYYY sharp !

If you have to -- take your plane body to an engine machine shop
and have tham take a finnish cut off the bottom - just like it was a
an engine head ...... It works great !

Tim

[violinarius]

[Michael Darnton]

Yes--things like that, which are short lessons and good for everyone, I will teach whenever anyone asks, even if it's not on the list of things to do.

[Dave Chandler]

Thanks for all your insights. I'm finally getting to understand the necessity for the spring gap in the middle, and it makes perfect sense. I also appreciate the information on techniques for holding the plane through the stroke, something I had not considered. I did take my "hercules" plane apart, attached the cutting parts to a 30" long shooting board made of aspen, and tried that as well, and I think I did better just with the plane itself.

Now I'm looking forward to getting some fresh wood to join. Thanks again.
_________________
Dave in the Blue Ridge
Southern Violin Association

"Success is the ability to go from one failure to the next with no loss of enthusiasm" Winston Churchill

"I took the road less travelled, and now I don't know where I am." Marco Polo

[byacey]

Purists may strongly disagree with me, but I use G2 epoxy on the back and belly center join. This is one of the things that you never need or want to come apart. I have had 100% success with a dead flat joint, epoxying and clamping. This joint won't even come apart after submerging the joined pieces underwater for months, and provides a neat, tight, invisible glue joint.