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I am now cleaning up the CNC'ed plates and laying down the purfling. I removed the hold-down tabs shown earlier. 

The first photo shows that I use only 4 purfling pieces for a back. I don't bother with mitering a join unless I am having a bad day with the knife.

89033376_PurflingStart.JPG.5ce84e6829c16e6b38d2ad1934d0a1e6.JPG

Notice that I use a medical scalpel for cutting the corners and adjusting the bee stings. The blade is only 0.4mm thick which is ideal for detailing wood. Although I do strop the blade, it is disposable. 

1769548176_PurflingDryLaid.JPG.5f6eb711a9c5865cd2bcf1410979210a.JPG

The purfling is dry-laid and now ready for gluing.

I have 2 backs and 3 tops on my bench for purfling.

 

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On 7/30/2018 at 1:12 PM, Peter K-G said:

 

On 12/17/2018 at 10:34 AM, Michael_Molnar said:

Thanks for the compliments.

Another experiment of mine is to transfer a wet lake into linseed oil without drying and mulling. I have had some good results. Most lakes that we make are amenable to direct transfer. Occasionally, I find some that clump (coagulate) which requires post-transfer mulling. Nevertheless, I like the results. I feel that more small particles get into the mix this way.

My setup is a hot plate that has a magnetic stirrer. I use the same oil from making varnish. To this, I add the wet lake precipitate scraped from the filter. I heat this to a little past boiling while stirring. I avoid excessively high temperatures that evaporate the linseed oil. My digital thermometer in the photo reads 7º too high when checked against a lab-calibrated thermometer. I maintain a slow boil until all bubbles and vapor clouds dissipate. It's important to get all the moisture out of this before using in an oil varnish.

I let the mixture settle for several days. Large particles precipitate out leaving a very clear solution. 

290063221_Transfernearcompletion.jpg.59e7d99df672ce6cbbe8ffff1524eb96.jpg

 

 

When I have tried the wet lake approach with spirit, the result was quite opaque.  I probably didn't get enough of the water out since I mixed the "mud" with alcohol and let it sit rather than heating it.  But I wondered at the time whether the particles ended up to small, effectively obscuring the movement of light. 

It would be interesting to know whether it is even possible to mull dried lake to the point where the pigment particles are as small as what you get with a wet lake.

 

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3 minutes ago, Julian Cossmann Cooke said:

When I have tried the wet lake approach with spirit, the result was quite opaque.  I probably didn't get enough of the water out since I mixed the "mud" with alcohol and let it sit rather than heating it.  But I wondered at the time whether the particles ended up to small, effectively obscuring the movement of light. 

It would be interesting to know whether it is even possible to mull dried lake to the point where the pigment particles are as small as what you get with a wet lake.

Alcohol (ethanol) always has water in it. You can never get all the water out of alcohol. (Read up on distilling alcohol.) My process gets all the water out by boiling in oil. (Sounds like an exercise in torture. :)

I do not dump the whole wet mass of pigment lake into the oil. I first preheat the oil to above 100C. I will go higher if I know this will not destroy the organic pigment according to what I learn about its stability given in various chemical databanks. (Google) I then put a dollop of the wet pigment into the hot oil and watch it sizzle like crazy while I stir. It's like sprinkling water onto a hot oiled frying pan. When done, I add another. I watch for water vapor above the oil. I understand that some pigments like to flocculate (form clumps). I would probably give those a quick mulling. So far I did not have to do that. 

 

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I finished scraping the top plate. Notice all the kinds of scrapers I use.

This spruce top is from log 1704 from Kevin Prestwich. I measured the density, ρ=0.364, which is my sweet spot. 

The plate needs wetting to raise the grain and then scraped again while making adjustments to the arching and fluting. Next. I will tackle the inside, edging, and graduation.

517556465_ScrapedPlate.thumb.JPG.d9e448aacaaaf80ed7947219762d0b2f.JPG

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That's a lot of scraper shapes to sharpen. I find one scraper to finish the plates is sufficient. You're very ambitious. The save written on the button is funny since you use CNC to cut out the plates.

Nice stingers.

 

 

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37 minutes ago, lpr5184 said:

That's a lot of scraper shapes to sharpen. I find one scraper to finish the plates is sufficient. You're very ambitious. The save written on the button is funny since you use CNC to cut out the plates.

Nice stingers.

 

 

I need the small scrapers for fluting and channels. They are a must for the scroll. 

As for the "Save" on the back button, I use the same pattern shape top and bottom. The button and rear tab (opposite to the button) give stiffness to the plate while machining outside and inside. I write "Save" only on the back plate before I cut off the mounting tabs pictured earlier. I cut off the back button only once when removing the tabs and swore never again. :(

Thanks.

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21 minutes ago, Urban Luthier said:

I like your long scraper  the centre -- I use one like that also. Does the CNC just score the f-hole outlines for you to cut through?

The f-holes are cut down to a depth of ~3.5 mm. When I graduate the roughed out plate, those f-hole plugs drop out leaving a clean shape. Sometimes I have to insert a thin scalpel to cut them out. 

I will give the specs and a photo of the f-hole end mill later.

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Here is the photo of the end mill I use for cutting out f-holes. The flute diameter is 0.030" (0.76 mm). The flute length is 8x the diameter. The shank is 1/8".  I purchased this from HarveyTool.com. That tip is very delicate.

1925118359_f-holeendmill.thumb.jpg.93e85c0f56966208cec15005cd351409.jpg

I run the router at 30,000 RPM and do three passes increasing in depth.

Now, here is where my expertise as a programmer comes in: I wrote the G-code so I can adjust the position and angle of the f-holes at the control station. I imagine that there are some CADCAM systems that can facilitate that, but I did it by hand. B)

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19 hours ago, Michael_Molnar said:

I need the small scrapers for fluting and channels. They are a must for the scroll. 

OK. I misunderstood. I thought you meant all those scrapers were for the top only. Making more scraper shapes for scroll work is something I need to do.

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  • 2 weeks later...

Here is my latest rendition of the ground I saw on Bruce Carlson' bench. The color is pretty good. This is the same ground I showed Bruce, but now "taken off steroids" as it were and toned down by incorporating casein. (See above photos.) This is under a 6400K fluorescent lamp (white light). 

Notice the glossy reflections from the wood on the left sample.

I have some other ideas for more experiments. Stay tuned.

IMG_1213.JPG.10d54b977965544d944299dccb34e395.JPG

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Next, experiment.

Here are photos of the samples made with casein mixed with a natural organic dye available to Cremonese makers. There are no modern components in the mix. This is quite lightfast. Same materials as in the previous photos.

As you can see the ground color is controllable and can be selected to fit one's taste. 

I would settle on something between the above photos and these. However, I do like the red dots in this ground.

588384878_P1040119(2)s.thumb.jpg.16e025397a7e3a3188bd6f4669d3f5e1.jpgP1040123s.thumb.jpg.646c8e7fdaa1dc654afda2068c8cd6a0.jpg

 

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On 12/17/2018 at 5:34 PM, Michael_Molnar said:

Thanks for the compliments.

Another experiment of mine is to transfer a wet lake into linseed oil without drying and mulling. I have had some good results. Most lakes that we make are amenable to direct transfer. Occasionally, I find some that clump (coagulate) which requires post-transfer mulling. Nevertheless, I like the results. I feel that more small particles get into the mix this way.

My setup is a hot plate that has a magnetic stirrer. I use the same oil from making varnish. To this, I add the wet lake precipitate scraped from the filter. I heat this to a little past boiling while stirring. I avoid excessively high temperatures that evaporate the linseed oil. My digital thermometer in the photo reads 7º too high when checked against a lab-calibrated thermometer. I maintain a slow boil until all bubbles and vapor clouds dissipate. It's important to get all the moisture out of this before using in an oil varnish.

I let the mixture settle for several days. Large particles precipitate out leaving a very clear solution. 

290063221_Transfernearcompletion.jpg.59e7d99df672ce6cbbe8ffff1524eb96.jpg

 

 

Very nice color Mike! Do you have the impression that this method improves transparency compared to the usual "cold mulling into the oil"?

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7 hours ago, Michael Szyper said:

Very nice color Mike! Do you have the impression that this method improves transparency compared to the usual "cold mulling into the oil"?

Thanks, but the jury is still out.

What I see so far is that some lakes/pigments flocculate in water and form large particles in the oil. However, there are lots of ultra-small particles that almost make the oil look dyed. An issue is that low viscosity (cold-pressed) linseed oils do not hold a lot of pigment which I want. Excess pigment precipitates out.  A high viscosity stand oil or a sun-bleached oil holds more pigment. I do not want to add a lot of oil to my lean varnish, so I need to get a lot of pigment into a small amount of oil.

The bottom line is that mulling is needed still to blend any pigment-laden oil into the varnish. I will give results over time. So, stay tuned.

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3 hours ago, Urban Luthier said:

Really nice Mike, your results look very transparent and the colour is nice to my eye. Have you done any tests where you've varnished over these? Looks like a nice base to start with

Thanks. I will be showing photos over time. A problem is that photos do not reproduce what we see. 

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3 hours ago, Michael_Molnar said:

Thanks, but the jury is still out.

What I see so far is that some lakes/pigments flocculate in water and form large particles in the oil. However, there are lots of ultra-small particles that almost make the oil look dyed. An issue is that low viscosity (cold-pressed) linseed oils do not hold a lot of pigment which I want. Excess pigment precipitates out.  A high viscosity stand oil or a sun-bleached oil holds more pigment. I do not want to add a lot of oil to my lean varnish, so I need to get a lot of pigment into a small amount of oil.

The bottom line is that mulling is needed still to blend any pigment-laden oil into the varnish. I will give results over time. So, stay tuned.

Sounds very interesting, i will stay tuned ;)

You are right, in a short oil varnish it seems to be pretty tricky to keep the color. I like oxidized varnishes a la Hargrave a lot and sometimes i think that it would be nice to get only a minimum amount of pigments in it, like a good spice. In this case your method could work pretty well. 

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Before I start on the next set of violins, I need to make some garlands. I have 4 PG forms and here is one modified with fence clamps. The corners need trimming and then I will add linings.

It's important to get the ribs fitting tight on the form. The c-bout ribs are glued after the ribs are thoroughly dry. If damp, they will shrink and leave a gap. Conversely, the upper and lower bouts are fitted with very damp ribs that will shrink as the glue dries. This produces a tight fit.

The lower bout rib is one piece ≥430 mm. 

675278866_FenceClamps.JPG.bded108b6778368a98e7a1e3b6eafadf.JPG

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3 hours ago, Michael_Molnar said:

Before I start on the next set of violins, I need to make some garlands. I have 4 PG forms and here is one modified with fence clamps. The corners need trimming and then I will add linings.

It's important to get the ribs fitting tight on the form. The c-bout ribs are glued after the ribs are thoroughly dry. If damp, they will shrink and leave a gap. Conversely, the upper and lower bouts are fitted with very damp ribs that will shrink as the glue dries. This produces a tight fit.

The lower bout rib is one piece ≥430 mm. 

675278866_FenceClamps.JPG.bded108b6778368a98e7a1e3b6eafadf.JPG

If the C-bouts will shrink and leave a gap would it be a good idea to fit the upper and lower ribs while wet?   Or will this cause a rib bulge (curvature) following the curvature of the 1/2 mold? 

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  • 2 weeks later...

I finished 4 garlands: blocks, ribs, and linings. The ribs are clean (glue ghosts exorcized :rolleyes:) and tapered,  and the scroll block is mitered (initial shape). I keep these glued on the form until I need one. This preserves the shape as shop humidity may change. Then I crack out the garland, clean up the linings, and shape the blocks. 

IMG_1250.JPG.715be6ad3ee06662bdac28829b1bd6a0.JPG

 

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  • 4 months later...

Time for me to give an update.

I will eventually explain some important findings about a plausible Stradivari varnish system. This agrees with B& G's, Echard's, and other findings, particularly the chemical trace elements. I should be done soon and have my fingers crossed that I can share my findings at the 2020 Orange, CA  meeting.

The last issue that is hanging me up is the top layer, colored varnish. I need to make a few violins with this system and get your feedback. The problem is, I believe, that Stradivari had several variations of his basic system. Examine photos of his work to see what I mean. Below is a photo of my varnish cookie no setup.

IMG_0454.thumb.JPG.30a769d90f1c61f9468f8d8cff32e2cd.JPG

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