Leveling rolled tone holes

[mirwa]

In abrasives, you have macro an microgrits, 600grit diamond file is a super fine grit, used for very fine sanding, the ability of something to cut through a surface is dependant upon the applied force and the sectional surface area of the material being cut, also the speed of the cutter play an important role.

The mathematics (Skip if you dont want to read)

Assuming its a new 600 grit diamond file, and you are using a battery operated drill at low speed (300rpm) , cutting a 1mm rolled edge with an outer diameter of 15.5mm, this gives a total circumference of 48.67mm (outer diameter) which leads to a distance of 14601mm of cutting travel per minute per particle grit or for our american counterparts (574.84 inches of travel per minute). With moderate applied pressure approx 200 grams of force ( which is about 3 times harder than you push closed a flute key whilst playing but you have the weight of the drill being applied) and a 600 grit particle has a size of 16 micrometers and there are upteen thousands of particles per disc, you have a rolled edge of about 8 thousands of an inch (0.2032mm). A single grit particle, should have cut through the tone hole edge in 12,700 passes (approx) (make it 25,400 so it has a 50 percent cut ration), add into this the thousands of particles per disc maybe even millions of particles per disc, and in reality you should have cut through in under a minute in my opinion

[mirwa]

Ducked up to workshop because I managed to do a deal on one of our hand made snare shells

If your not to sure what I am talking about I have attached pictures (pretty happy with these) solid tree trunks turned into drums, I have just cut and pasted some examples of our work

[mirwa]

Whilst I was there however, I quickly grabbed a flute from my junk draw and put the theory into practice,

At one minute mark I took a photo, wasnt through the tone hole, at a minute and a half I had cut through, so I started to peel the rim away

Now no one runs a battery drill on low speed for a minute against a tone hole, IMO that is just stupid, but this is what I find happens

[mirwa]

could only upload 3 at a time, disc is a jl smith 600 grit diamond disc brand new

[HMannfan]

Steve,

Many thanks for taking the time to demonstrate how NOT to level tone holes. That was a tremendous amount of grinding on a single tone hole to cause failure.

I think you made the point for all of those techs who are in favor of judicious hand sanding/grinding with a fine hone. Taking 1 thou. to 2 thou. off a tone hole to level it seems like a perfectly legitimate and safe method. Without damage being done to the tone holes in the future, this should only have to be done once.

Mark

[mirwa]

Please don't mis-understand me,

I'm not advocating against filing, just to use real caution if one chooses to do it, I advocate against filing to anyone just starting out,

With experience comes understanding of ones capabilities and of the materials one works with, and then all methods can be utilised, my earlier point was some people just go blindly into something and just do it, serious consequences can arise in a fast period of time when this approach is taken

[fluteguy18]

Ah. This is where you and I have a difference of approach. I was using the exact same file and was working on a low C tonehole on an old Selmer. I only ever file by hand and only do 4-5 rotations at a time. I use a sharpie to tell me when I have reached 'level.' Once I see that it is just barely level, I reapply the sharpie, do a single rotation to see if it is 'true' and stop there. Now... as to why the grit stripped off so quickly I am not sure. I plan on making a call to JL Smith to see if they have anything to say. It was a brand new file.

I also want to explain something for the OP that hadn't been explained. Joe mentioned that the majority of the distortion that he sees is from the washer/screw tool that lowers the rim by rolling. He has a very valid point there. As metal gets worked it hardens. There is a point at which you work harden the rim to a point where it is harder than the chimney beneath it. At that point the walls tend to crumple and distort. You just have to know where that point is so that you don't cross it.

[HMannfan]

Steve,

I understand and agree completely. I'm still looking forward to the next experiment. I'm sure that it will support the alternate method too.

Your dead flute drawer is amazing! I had not conceived of anyone amassing so many. I imagine most of these are simply a case of a cheap student flute not worth repairing because the repair costs would exceed the flute's value. I wish I had a few to practice on!

By the way, I don't know anything about drums, but your's look great. You are rightly proud.

Mark

[fluteguy18]

Yes. Beautiful work indeed.

[mirwa]

Mark, that is one of a couple of flute draws, cheapies like yamahas / armstrongs / gemeinhardts, (the mechanical work and repad work makes them uneconomical to repair), on really worn out chinese units I wont even keep the carcass, they go straight into the bin or turned into a light

[JButky]

could only upload 3 at a time, disc is a jl smith 600 grit diamond disc brand new

That's a really aggresive way to file a tone hole! Power tools! How much downward pressure applied?

As you know, there is no "feel" when a power tool is used like that.

To put this in perspective, you can try and flatten a car by hand with a sledge hammer or you can use a car crusher. This is definitely the car crusher approach!

[mirwa]

Joe - When you recut a sax tone hole / clarinet tone hole / oboe / bassoon etc tone hole, how do you approach it, I always use a battery drill, but yes I do it by hand when doing a flute, as I am aware of just how thin the material is.

Yes I agree re this flute, definetly was the aggressive approach, my point was with moderate pressure how long would it take to cut through it, not "this is how you should do it", as I am sure by now you are aware, I am not a fan of any filing at all, but there are times even when that is still warranted.

[mirwa]

Flutes are a bit too reflective for laser scanning and trying to get intricate measurements from, may try to see if I can dull the reflective surface down for a successful trial

[JButky]

Joe - When you recut a sax tone hole / clarinet tone hole / oboe / bassoon etc tone hole, how do you approach it, I always use a battery drill, but yes I do it by hand when doing a flute, as I am aware of just how thin the material is.

Never have used power tools for these operations. Have always done leveling and finishing by hand.