Recommended Posts

Here are a pair of photos I snapped off before the Sun got too low. This is the violin that I took to Robson's Varnish Workshop in Concord last month. Since returning I have added another two very thin coats of varnish, not uniformly, but trying to highlight certain aspects. This is a mixture of Greek Pitch Brown and Rose on top of Joe's Balsam Ground.

 

post-6615-0-56087700-1367618183_thumb.jpgpost-6615-0-61421400-1367618210_thumb.jpg

 

And here is a photo Kory Klein took of yours truly at that workshop.

 

post-6615-0-47821600-1367618662_thumb.jpg

 

As you can see I just started to varnish that violin.

 

 

Stay Tuned.

Share this post


Link to post
Share on other sites

As you can see I just started to varnish that violin.

 

 

Yes, that's obvious by the clean, white apron with no varnish stains on it.

 

Betts model?  Bisected pin plugs for show, or do you actually use them for location?

Share this post


Link to post
Share on other sites

Yes, that's obvious by the clean, white apron with no varnish stains on it.

 

Betts model?  Bisected pin plugs for show, or do you actually use them for location?

I believe the white apron was Marilyn's idea. We printed our name on it instead of wearing a name tag. However, my apron collected lint  like cat hair does to a dark suit. So, I ditched it after 4 days and used my own apron.

 

Good call, Don! Yes, the Betts strongly influences my design. The pins are dark stained toothpicks and just decorative. At one time, I did use pins for alignment, but they just slowed me down and added little to the process.

 

Thanks, Ernie and Chris, too.

 

 

Share this post


Link to post
Share on other sites

Dark stained toothpicks?  roll.gif

 

Actually, I did that exact same thing on a VSO rebuild.  Looks pretty good.  

 

Love the varnish... and the Betts is one of my favorites.  :wub:

Share this post


Link to post
Share on other sites

Thanks, Carlo & Jessupe. Yes, this is CNC'ed. However, that means all the grunt work was done by machine. There is still a helluva lot of finessing to get things right. :blink:

 

And yes Addie, my dark secret is that I use  toothpicks. I soak them for a few hours in walnut shell stain. We have something in common, indeed.

 

Mike

Share this post


Link to post
Share on other sites

Mike,

 

I seem to recall you use CNC to do the purfling groove, and I presume you also cut the plate outline on the CNC too. 

 

If that's so, how do you get the garland precise enough to match up with the plate?  Any trouble with overhang variation?

 

And how come your avatar turned into a ghost?

Share this post


Link to post
Share on other sites

Hi Tim,

 

Yes Joe's technique for "flaming" works.

 

Don,

 

Yes, I cut the purfling groove with the CNC, but bee-stings are done by hand using a scalpel. The plate outline is also CNC'ed which makes alignment easier. This is not as easy as it sounds. Garlands are like rubber, and there can still be overhang problems. There are a few tricks. Next time we get together I'll be glad to explain the details.

 

As for my avatar, I tried to update the photo only to find that the photo editor does not work. The sick software even clobbered my old avatar, so don't touch yours.

 

I have complained to Jeffrey and ghunt about it. Jeffrey says he can't do anything. ghunt says he's only part time and passed the buck to someone else. I even contacted the makers of this site's software, and they hid behind customer confidentiality. All this was WEEKS ago. I started a thread on it in another forum.

 

I noticed that quite a few other people's avatars are ghosts.

 

Mike

 

 

Share this post


Link to post
Share on other sites

Thanks, Carlo & Jessupe. Yes, this is CNC'ed. However, that means all the grunt work was done by machine. There is still a helluva lot of finessing to get things right. :blink:

 

And yes Addie, my dark secret is that I use  toothpicks. I soak them for a few hours in walnut shell stain. We have something in common, indeed.

 

Mike

Oh by no means am I against machines, heck I use a lancelot rig. We all can't be like Burgess and have strapping thighs. :lol:  I agree the last "layers" are where its at. Rough work I'll use anything that is safe and easy on my body.

Share this post


Link to post
Share on other sites

Oh by no means am I against machines, heck I use a lancelot rig. We all can't be like Burgess and have strapping thighs. :lol:  I agree the last "layers" are where its at. Rough work I'll use anything that is safe and easy on my body.

Lancelot? I toyed with one and decided to keep my fingers attached to my hands. Using one of those safely is a real skill.

 

And yes, a machine is largely for making grunt work easier. It is no shortcut to craftsmanship. In fact, it can easily get in the way of craftsmanship. ;)

 

However, some of us use that grunt work to develop our bodies into massive hulks. :rolleyes:

 

Mike

 

 

 

Share this post


Link to post
Share on other sites

 

And yes Addie, my dark secret is that I use  toothpicks. I soak them for a few hours in walnut shell stain. We have something in common, indeed.

 

Mike

 

 

Right, you’re an innovative, cutting edge VM, and I tinker with VSO’s.  That puts us on a par, right?  

 

What?  umno.gif Oh, OK. 

 

 

 

 

:)

Share this post


Link to post
Share on other sites

Mike,

The varnish is looking great.  Next time we will wash the aprons with some fabric softener to cut the lint factor.

Live and learn.

Joe

Share this post


Link to post
Share on other sites

Hi Mike!

I'm interested in the CNC machine. So I have a couple questions regarding the exactness of the machinework. How close can you get to the finished surface? It would be helpful if you could post a close up of the machined surface, perhaps in skewed light?

Share this post


Link to post
Share on other sites

Evan,

 

I took off my baseball catcher's mask before the photo was taken.  :D

 

Torbjörn,

 

I do not finish the work surface with a CNC. I use the CNC to rough out my contours. Some machined areas with low slopes can look finished, but other areas can have a 0.2 mm step that gets smoothed with a scraper. I prefer working this way after several years of R&D.

 

I know some makers use their CNC to make a final finish with dazzling results. Some use 4-axis machines that produce incredibly smooth finishes. 

 

If you want more CNC info, send me a PM.

 

Mike

Share this post


Link to post
Share on other sites

 how do you get the garland precise enough to match up with the plate?  Any trouble with overhang variation?

 

 

Don,

 

Now I found time to take a couple of photos to show what I do.

 

The first photo shows the standard Strad PG one piece form. Nothing special about it. I used F. Denis' methods to make it. Denis, Kevin Kelly, and others gave me a lot of good advice in constructing the PG form especially the issue with the c-bout construction. I will comment more on this issue later.

 

IMG_0557.JPG

 

The second photo shows my collapsible form.

 

IMG_0556.JPG

 

I remove the garland from the standard one-piece form and insert this form into the garland (after reducing block sizes and shaping the linings). I turn the black wheels to open and close the form, and adjust the separation to get the correct form shape. I use clamps (removed to take this photo) to make sure the garland conforms to the collapsible form. Then I clamp this unit on my plate for gluing. When done I turn down the wheel screws to reduce the form and remove it. If you look closely you can see the three sliding dowels that ensure perfect alignment of the two sides. I used 1/4" steel dowels that slide in bronze sleeves. I made the thumb screws from the parts of a small parallel clamp to which I added the blackened oak wheels. The wheels are pinned to the screw shaft.

 

I have no alignment problems with this jig.

 

Mike

post-6615-0-10378600-1370868796_thumb.jpg

post-6615-0-69004200-1370868848_thumb.jpg

Share this post


Link to post
Share on other sites

Mike,

I know you said you clamp the garland to the collapsable form, but I saw this:

Detail.png

and it appears that the bend of the garland is not a great match to the curve of the form. Perhaps it's just the angle of the photo, or lighting... but it looks like it would take quite a bit of clamping force to mate it up.

I do like the idea, and the mold is cool.

How precise and even can you get your overhang? On my last one (first out of my new mold system), the best I could do was 2.1 - 2.7mm overhang in the upper and lower bouts (C bouts I don't care as much). That's after pushing and tweaking as much as possible. Perhaps I'm at a disadvantage, having to make all my templates and molds by non-CNC methods. But even with CNC, avoiding a .1mm or so deviation at each operation seems difficult, and can add up to visible variations between the garland and precut plate.

I suppose on option is to leave the plate .2 - .3mm oversize, and do the final overhang ajustments after the body is assembled, which would then result in more variation of the purfling/edge distance. Maybe that wouldn't be as obvious? I do intend to do a little more overhang adjustment just prior to varnishing my latest one, reducing the 2.7mm overhang areas.

post-25192-0-51720300-1370871502_thumb.png

Share this post


Link to post
Share on other sites

I said I removed the external clamps for taking the photo. I place two clamps squeezing the garland at the corners. No, the clamping force is not great; finger pressure can do the trick. The garland always wants to spring like a rubber band. With the corner clamps, the garland takes on the form shape perfectly. There is no gap. Nadda! I remove the corner clamps once the garland is fixed to the plate using the Herdim rib clamps. (I love them.) The Herdim clamps also ensure perfect contact all around the form. Remember, you always need to push inward with an inside form, or outwards on an external form.

 

This jig gives me easily 0.1 mm accuracy. Any deviations from this form are from my hand finishing of the rib thicknesses and edging. I never leave a machined surface untouched. Plate edging is also by hand.  I guess there is a misconception that CNC's do everything. Not in my shop. I use it for consistency and avoiding grunt work. Workmanship is still by hand. However, there is also another kind of workmanship involved with CAD drafting and running a CNC. Few people can appreciate that.  :)

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.