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Binding channel cutter

Posted: Mon Apr 06, 2015 1:15 am
by charangohabsburg
There are actually two tools needed: a cutting gage and a scraping gage. Well, make it five tools if you count in a chisel, plus a knife and needle file for clean-up). Time required to cut all channels: about one hour after having gotten familiar with the process.

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The chisel-shaped scraping blade can be ground from a cheap square needle file. It needs sharpening and honing, a bevel angle of about 45° works fine for me (different scraping action depending on scraping direction).

First, using the cutting gage the borders of the channel must be cut to a depth of about 0.7 to 1.0 mm. Then the scraping gage cuts the rest of the depth in the sides, respectively 1 mm deep into the top and back, right adjacent to the cuts made with the cutting gage.

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Then, again using the cutting gage the rest of the remaining material in the channel gets cut away:

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The narrower the scraping-chisel is, the faster the channel will be cut to its whole depth. My blade is about 2 mm wide, which is on the wide side. 1 - 1.5 mm would be better, but the blade's shaft where it gets clamped should be thicker, unless a more sophisticated clamping mechanism is made (this square blade sits in a round hole in the wood, thus gets bent when clamped, so over-clamping could be fatal for the blade).

Here's another view of the scraping tool, showing more of the blade clamping mechanism:

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Re: Binding channel cutter

Posted: Mon Apr 06, 2015 7:28 am
by Localele
Nice job Markus.You could grind your blades out of round High Speed Steel to fit the hole.
Here are some photos of my version.
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Finished cutters
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Like this to cut the top
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Like this for around the sides.Note the cutter needs rolling over in this photo to get the bevel on the right side.This was just for photos.

Re: Binding channel cutter

Posted: Mon Apr 06, 2015 10:14 pm
by charangohabsburg
Localele wrote:Nice job Markus.You could grind your blades out of round High Speed Steel to fit the hole.
Thank you Micheal. It is actually not a real issue with the square blade in the round hole, I only mentioned the possibility of over-tightening to prevent someone could put the blame on me if he breaks the blade for behaving like an elephant. In fact, a square blade (shaft) in a round hole has the advantage to require a minimum of clamping force to hold it firmly in position.
Localele wrote:Here are some photos of my version.
Beautiful tools. Too bad I am not equipped to do proper metalworking - which may be the main reason why I'm not so fond of it. I prefer to grind a needle file to shape than an 8mm thick HSS rod. :)

Re: Binding channel cutter

Posted: Tue Apr 07, 2015 5:07 am
by Localele
The tolerance and fit of "real metalworking" are addictive.Using a milling machine with a DRO for measurements making fret scales really makes it easy and fun.Same for drilling bridges for string spacings.You soon realise the need then for a small precision lathe to make the other parts to the same standard.
All this can take you away from woodwork a bit though as you move over to making your own metal parts.I like to think it is a logical positive step and enjoy it immensely.
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Turning knobs for my Rosette Cutters

Re: Binding channel cutter

Posted: Tue Apr 07, 2015 5:16 am
by charangohabsburg
I am more on the handmade lane. For me, tolerances serve a purpose, not an addiction.