Current Build - Falcate Braced Multiscale OM cutaway

[kiwigeo]

Hey Martin, how thick are those bindings? Maybe that's why the blackwood was so difficult?

These BRW bindings are 2mm thick but the blackwood bindings were alot thinner. The BRW bends easily even at 2mm thick.

[kiwigeo]

Top bindings scraped back and everything trued and trimmed up. Just the butt graft to go on and thats the body done. That cutaway was a f****ng pain to get right...but man with the binding done it sure looks worth the effort!!

[Trevor Gore]

Hey Martin, how thick are those bindings? Maybe that's why the blackwood was so difficult?

These BRW bindings are 2mm thick but the blackwood bindings were alot thinner. The BRW bends easily even at 2mm thick.

Must be a trick of the lens . They look a lot thicker than my 2mm bindings. I was assuming each B and each W was 0.5mm.



I do the blackwood ones at 2.0mm, about 6.5 - 7.0 high and then a B/W on the bottom takes them to ~8.0mm high, all up. Bending around the cutaway tends to go OK, but getting the "crown" bent in bindings that tall for the 3m back dome isn't too easy.

Anyway the BRW is looking pretty good!

[kiwigeo]

Yeah Im happy with the BRW.....the colour actually goes well with the Coobah in the rosette.

[jeffhigh]

Lookin good Martin, I'm keen to see the way this comes together.

[kiwigeo]

Lookin good Martin, I'm keen to see the way this comes together.

Thanks Jeff. It's coming together but progress is slow and the learning curve is steep. Today Im taking a day off from the building...need to review the drawings and have another look at headstock design and a few other things.

[kiwigeo]

Did some tap tests today:

T(1,1)1 - 104Hz
T(1,1)2 - 194.7Hz
T(1,1)3 - 232Hz

Ive only got around 14Hz to play with for the T(1,1)2 so the bridge will have to be as light as I can go...around 25gm max. I think I can get there with a walnut/CF bridge with as much meat shaved off as possible. Hopefully Ill start seeing the back resonance once T(1,1)2 is closer to target of 180Hz.

I double sided taped a series of dummy bridges to the top and the drop in T(1,1)2 pretty much worked out at 0.6Hz/gm

[Jeremy D]

Hi Martin,

Build is looking great. I wanted to ask you about your technique with the stewmac scraper. I might just be an idiot but I bought one and tried it on the binding on my latest build and couldn't get it to work well. I went back to traditional card scraper which was much more effective. Any tips?

[kiwigeo]

Hi Martin,

Build is looking great. I wanted to ask you about your technique with the stewmac scraper. I might just be an idiot but I bought one and tried it on the binding on my latest build and couldn't get it to work well. I went back to traditional card scraper which was much more effective. Any tips?

Hi Jeremy,

I find Im using my Carruth scrapers more than my card scrapers these days. The main trick with the Carruth scrapers is to get a good edge on them on the grind stone. I first lap both sides of the scraper on a Japanese water stone and then dress the edge on the grinder with a fine stone. The important thing is to make sure the face of the wheel is exactly flush with the edge face of the scraper. I run a felt pen over a section of the edge so i can see where the stone is taking metal off the edge. Working on bindings I use the larger Carruth scraper and I make sure that most of the flat edge is registered on the guitar side so the bindings stay square to the top.

Hope this helps

[Jeremy D]

Thanks Martin,

I guess I just assumed they came sharp enough to use. I will have a look at sharpening it.

Cheers.

[kiwigeo]

Thanks Martin,

I guess I just assumed they came sharp enough to use. I will have a look at sharpening it.

Cheers.

Jeremy, those scrapers come with instructions on dressing them. Let me know if you don't have the instruction sheet and I can flick you a scan of mine.

[kiwigeo]

From Stewmac website:

Sharpening the Ultimate Scraper
Keep the scraper sharp with a fine-grit grinding wheel and a sharpening stone (or fine grit sandpaper on a flat surface). The wheel's curvature creates a hollow-ground (concave) edge, and the flat sharpener keeps the sides clean and flat.

Flatten and smooth the sides with a circlular motion on a sharpening stone (or fine sandpaper on a smooth surface as shown here).

Flatten and smooth the sides with a circlular motion on a sharpening stone (or fine sandpaper on a smooth surface as shown here).

Lightly grind on exact center all the way around the scraper.

Lightly grind on exact center all the way around the scraper.

For a good cutting edge, the scraper's sides must be smooth and flat; if they're uneven, the edge will be uneven, too. Smooth the sides of the scraper by laying it on your flat sharpening surface and sliding it in a circular motion.

Set your grinder's tool rest so the wheel touches at the exact center of the 1/8"-thick scraper. If you lightly touch the scraper to the turning wheel, the mark created shows whether you're centered, or whether the tool rest needs adjustment. Coloring the edge with a felt-tip marker will make these marks easier to see.

With the wheel lightly touching the exact center of the scraper edge, grind around the entire edge of the scraper.

Between grindings, you can keep the sharp edge by whetting on the flat sharpening stone (or sandpaper). Lightly dress each side, then turn the scraper and dress the straight edge.

[Jeremy D]

Thanks heaps Martin

[Mark McLean]

When I got my Carruth scraper I tried it straight out of the box and it did nothing. But after you set them up they are great, and I now prefer it to a traditional card scraper.
Martin has covered it above, but if you prefer pictures, Al's video on the Stew-Mac website walks you through the sharpening process pretty well.

http://www.stewmac.com/How-To/Tool_Demo ... -0631.html

[Jeremy D]

When I got my Carruth scraper I tried it straight out of the box and it did nothing. But after you set them up they are great, and I now prefer it to a traditional card scraper.
Martin has covered it above, but if you prefer pictures, Al's video on the Stew-Mac website walks you through the sharpening process pretty well.

http://www.stewmac.com/Luthier_Tools/Ty ... raper.html

Makes sense thanks Mark. Don't know why I thought it should be setup and ready to go. I would never buy a hand plane or chisel and expect it to be setup and sharp. Cheers.

[blackalex1952]

In the interest of my McBudget,as an ex picture framer I have lots of old glass offcuts lying around and an oil cutter. I use bits of freshly cut glass as scrapers a lot of the time (must use an oil cutter with kero in it). They lose their edge quickly so as soon as the glass fails to pull shavings I quickly cut myself a new one-most curves are easy. Faster than sharpening scrapers for small jobs like bindings. Blackwood and spruce tend to blunt them quickly, so would use metal scrapers for archtop soundboards and blackwood sides. But bindings are no problem. I rub the corners of the glass on carborundum paper to make sure the corners don't damage the soundboard or whatever I'm scraping as one cant bend glass like one can bend a thin scraper. The other way is to cut the glass straight with a curve at the end. Can also use masking tape either side of the cutting surface. Dan Erlewhine does this with razor blades when finish repairing and scraping CA fill flush.

[kiwigeo]

Not much work in the shop today. Ran some Coobah burl through the drum sander for the butt strip but cracked the wood in half while prizing it off the carrier board. Gave up and went to the pub for the rest of the day.

[kiwigeo]

Coobah burl butt strip to match the rosette.

[johnparchem]

The burl looks great! Nice choice.

[kiwigeo]

The burl looks great! Nice choice.

Thanks John. The coobah is brittle stuff to work with but I managed to pull it off in the end.

[Crafty Fox]

The coobah is brittle stuff to work with but I managed to pull it off in the end.

Why did you pull it off? I thought it looked great.

[kiwigeo]

A bit more progress in between heat waves here in Adelaide. Got the neck mortise cut and the neck bolt holes drilled after rough fitting the neck. Still about 0.5mm low at the saddle but will fine tune that to the requisite 2.5mm.

[Mark McLean]

So - a piece of masking tape up the middle of the top so you can draw a line to get the neck aligned with. That is very simple and smart. Am I the only one who hasn't ever thought to do that?

And just how many neck blanks do you have stashed away there?

[kiwigeo]

So - a piece of masking tape up the middle of the top so you can draw a line to get the neck aligned with. That is very simple and smart. Am I the only one who hasn't ever thought to do that?

And just how many neck blanks do you have stashed away there?

The masking tape...it's there because the centre line doesn't always coincide exactly with the top join.

The pile of neck blanks in the background....left side of the pile is Fijian Mahogany but it's flat sawn. I slice it up and make laminated necks with the grain going in a more favourable direction. Also in the pile is a fair bit of Spanish Cedar...alot of it bought before it got CITES listed.

[kiwigeo]

Neck thicknessed with the Safe-T-Planer and the heel block shaped.