Luthier tips du jour - Inlay tool tip

[Robbie O'Brien]

Here is the latest Luthier Tips du Jour video - In this video I offer a viewer a tip about how not to break bits when doing inlay work. This video as well as all my other videos are available via my website, http://www.obrienguitars.com/videos , LMI's website or on youtube.

youtu.be/

[blackalex1952]

Damn! Does this mean I need more tools???
Seriously though, is there ever an issue with a bit overheating at this speed, particularly with hi silica content woods? -Ross

[Mike Thomas]

I don't think there would be an overheating problem for these small diameter bits. At 60,000 rpm the cutting edge of a 1/32" bit travels at the same speed as a 1/16" bit at 30,000 rpm, i.e. Dremel speed. I don't think carbide bits of that size or larger (e.g. 1/8") overheat when using a Dremel, so 1/32" at 60,000 should be fine. I imagine that the material being cut is more likely to be the issue.

[kiwigeo]

Is it overheating that leads to broken cutters or is it excessive lateral stress the bit is subjected to when you hog out too much in one pass?

[simso]

Like button for Robbie’s post.

Not to take away from said post, it’s feeds and speeds. 60,000 rpm is some serious speed, I did in my younger years, fitting and machining as part of my mechanical apprenticeship.

I machine shell and ebony with.3mm cutters at 10,000 rpm on my small machine, I machine ebony and rosewood on my big machine at 24000 rpm. Both run at different feed speeds.

I know of people out there, running machines at 100,000 rpm.

The only time the cutters break is when I have my feed going to fast for my cutting edge to clear the job.

When I do it by hand, I go slow.

Steve

[demonx]

Basically what Steve said.

That and, when I watched the video I'm thinking the bit he's demoing with is ~0.8mm, at that thickness in the CNC I can run at virtually any feed speed and spindle rpm and it'll not break unless you try doing something dumb.

It's when you go down to 0.5mm or less that they snap just by looking at them, I've snapped 0.5mm accidentally by pulling the airgun a bit too hard when clearing dust. Damn that pissed me off, I invested in a air nozzle which I fitted on the spindle after that so it didn't happen again.

[Dave M]

I notice that the actual tool he's using is pretty cheap. However I have no feel for what the compressor required would cost and the tooling.

Are air tools worth thinking about in more general terms...?