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Files and TPCm

I was giving my skis some pre-season love this morning, and I noticed that while the file's box says "17 TPCm" -- which I always assumed meant "threads per centimeter", the file itself doesn't measure anything close to that:

Am I missing something?  I trust my caliper which is reading 10mm = 1cm, and that's seven, not seventeen, threads on the file.

It stand for Teeth Per Centimeter.

Now I am trying to find how you measure that

So here is what I found, apparantly is not howw mnay teeth per lineal Centimeter.

It is a measurement of pitch of the teeth.

Pitch of toothing is the distance between one point on a tooth and the same point on the following tooth. In general "Pitch"  is expressed  in Teeth per centimeter.

Don't know if I am straight on this or more confused. Good news the higher the # the finer the and shallower the teeth!

Quote:
Originally Posted by Atomicman

So here is what I found, apparantly is not howw mnay teeth per lineal Centimeter.

It is a measurement of pitch of the teeth.

Pitch of toothing is the distance between one point on a tooth and the same point on the following tooth. In general "Pitch"  is expressed  in Teeth per centimeter.

Don't know if I am straight on this or more confused. Good news the higher the # the finer the and shallower the teeth!

I'm not sure I follow that...  "the distance between one point on a tooth and the same point on the following tooth" to me sounds like the linear gap between two teeth?  Which, as my picture above shows, there's no way you get to 17.

But then you say "the higher the # the finer the and shallower the teeth" sounds like the TPcm number has to do with the height of the teeth, not the gap between them?

Quote:
Originally Posted by KevinF

I'm not sure I follow that...  "the distance between one point on a tooth and the same point on the following tooth" to me sounds like the linear gap between two teeth?  Which, as my picture above shows, there's no way you get to 17.

But then you say "the higher the # the finer the and shallower the teeth" sounds like the TPcm number has to do with the height of the teeth, not the gap between them?

It has to do with the pitch of the teeth so maybe you need to measure from the top of one tooth to the same point on the teeth on the opposing side one CM away so your tool is angled (the measurement is at an angle) as I said it is not tooth depth and it is not linear measurement

Quote:
Originally Posted by KevinF
" sounds like the TPcm number has to do with the height of the teeth, not the gap between them?

Think of it this way - a 200 dpi printer that only prints 6 dots in an inch is still printing at 200dpi.

Now let's say the teeth are sized so that you can fit 17 of them, including gaps, in a centimeter.

If you leave 10 of those teeth out it's still a fine-cut file.   Tpcm then becomes a measure of tooth size, not tooth density.

BTW, you can somewhat confirm by doing an overlay/photoshop of the file pic back onto itself, offset by a half tooth.

From that pic, it looks like it's not a 17. Do ya have another file to compare with?

Just snapped these two pics. Micrometer is at 1 cm. one file is 12tpcm and the other is a 20tpcm.[IMG]
Quote:
Originally Posted by Chenzo

From that pic, it looks like it's not a 17. Do ya have another file to compare with?

It's my one-and-only file.  I usually maintain my edges through diamond stones, so my file sees little use.  It works, I was just wondering how they get to 17 tpcm.

Your pictures show what I would suspect.

Following up on what tuna said,

It looks like Chenzo's files have tooth-tooth-tooth....

while Kevin's have tooth-flat spacer-tooth.

So I guess it's the equivalent teeth per centimeter you would have if the spacer was filled with more teeth.

Yep, size of one tooth seems to match pretty well,

the original image does not look like any of my fine files!
Quote:
Originally Posted by Chenzo

From that pic, it looks like it's not a 17. Do ya have another file to compare with?

Just snapped these two pics. Micrometer is at 1 cm. one file is 12tpcm and the other is a 20tpcm.[IMG]

I count 17 ridges in that Cm in the top picture. Don't you ?

Quote:
Originally Posted by Max Capacity

Quote:
Originally Posted by Chenzo

From that pic, it looks like it's not a 17. Do ya have another file to compare with?

Just snapped these two pics. Micrometer is at 1 cm. one file is 12tpcm and the other is a 20tpcm.[IMG]

I count 17 ridges in that Cm in the top picture. Don't you ?

The caliper is not well-aligned with the teeth - I get 19 on the left side of the file and 17 on the right.

So here we are counting teeth on a file. How sad is that...LOL

Quote:
Originally Posted by Max Capacity

So here we are counting teeth on a file. How sad is that...LOL

It COULD be worse!   Imagine if we were also  going on about the relative inaccuracy of calipers and pooh-poohing the generic chinese plastic ones....

Quote:
Originally Posted by Max Capacity

I count 17 ridges in that Cm in the top picture. Don't you ?
I was wondering when someone would notice. I counted 18 almost 19. It's a brand new T104x and it says 20 on the sleeve. I Was a bit surprised, and I counted a few times to make sure. I guess swix just rounded up. Haha

I was wondering if you count in the cutting direction or perpendicular to the teeth.

Quote:
Originally Posted by Chenzo

Quote:
Originally Posted by Max Capacity

I count 17 ridges in that Cm in the top picture. Don't you ?
I was wondering when someone would notice. I counted 18 almost 19. It's a brand new T104x and it says 20 on the sleeve. I Was a bit surprised, and I counted a few times to make sure. I guess swix just rounded up. Haha

Do you have a second caliper?

Actually, it does seem to be perpendicular to the teeth.

The green line, along the cutting direction, tooth 1 to 18.5 = 17 teeth.

The blue line, perpendicular to the teeth, tooth 1 to 21 = 20 teeth.

Is it snowing yet?

So I went out and bought another file for comparison purposes:

The top one is the new one.  16 Tpcm (and counting it seems to bear that out).

The middle one is the one that started this whole thread.  Supposedly 17Tpcm...

And the bottom one is a panser file.

Seems like the middle one has more in common with the panser file that it does the other one...  Just saying...

And yes, it needs to start snowing.

Quote:
Originally Posted by KevinF

So I went out and bought another file for comparison purposes:

The top one is the new one.  16 Tpcm (and counting it seems to bear that out).

The middle one is the one that started this whole thread.  Supposedly 17Tpcm...

And the bottom one is a panser file.

Seems like the middle one has more in common with the panser file that it does the other one...  Just saying...

And yes, it needs to start snowing.

You are saying correctly.  Maybe the file was packaged incorrectly.  Just use it and finish with stones.  You can't have too many files.  Stones will wear out too, so be prepared to but more.  You can't use too much fluid with stones!
See here : https://youtu.be/aUZQ0isiPIQ?t=2m40s

Quote:
Originally Posted by mdf

Actually, it does seem to be perpendicular to the teeth.

The green line, along the cutting direction, tooth 1 to 18.5 = 17 teeth.

The blue line, perpendicular to the teeth, tooth 1 to 21 = 20 teeth.

Is it snowing yet?

This is basically what I was getting at in the explanation, many posts ago Here:

It has to do with the pitch of the teeth so maybe you need to measure from the top of one tooth to the same point on the teeth on the opposing side one CM away so your tool is angled (the measurement is at an angle) as I said it is not tooth depth and it is not linear measuremen!