Cutter size compensation

[asimpson]

Waiting for our new machine to arrive to test all of the great information I have read in the forums.
Now the question.
In Vector after having programed a sheet full of parts with a .25 tool path offset, how do I deal with a bit that has been sharpened and is now less than .5 diameter?

[bruce_clark]

Mr. Simpson,

You reoffset all your original geometry to the new diameter of your cutter.

Bruce Clark

[rgbrown@itexas.net]

Alan,

You have several options:

Buy a new bit.

Figure new offsets and redeaux the parts.

There is a point in VECTOR where you will learn to save the file in Vector's native format. I seldom make more than a few of a part so I can't tell you where that point is.

Ron Brown - rgbrown@itexas.net (mailto:rgbrown@itexas.net)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[asimpson]

From what I understand about Vector you select your part profile and do a offset line that is the distance of the radius of your cutter. That new series of lines is used to define your tool path. Does that process have to be repeated for every different size cutter or can you adust the values on the offset lines after they have been created? Redrawing the offsets would be a pain on a job with many parts laid out on a sheet.

[gerald_d]

"Does that process have to be repeated for every different size cutter" Yes, the process must be repeated manually. (From my current knowledge of Vector and other affordable CAM programs).

However, Vector makes the selection of a shape, and generation of the offset line very easy and fast. For us this is the main power in CAM programs - don't let somebody tell you that they do it quicker in TurboCad (just because they have discarded Vector as "too difficult")

The cutter diameter is only one of the factors that determines the offset distance. Another very big factor is the flexibility of the machine and the material being cut. The cutter is deflected away from the theoretical position depending on the cutting load. Typically we would use an offset of 2.75mm for a 6.0mm cutter. Re-sharpening is less than 0.1mm at a time. Therefore in reality, we don't worry about new offsets for re-sharpened cutters.

Most of our work (like boat parts, signs, ornaments, decorations)is perfectly fine if we keep a 0.25mm tolerance. When a very fine job does come along, then we cut a small test sample, measure the result, and change the tool offset accordingly.

[alano]

Possibly I am viewing this as being too simplistic. My approach would be to mic the 0.25 bit to determine the amount that it is now undersized (post sharpening) and then change the cutter tool size within the ShopBot program itself - rather than recalculating a new offset in Vector.
Regards,
Alan Overby

[asimpson]

Alan tell me more. I had not realized yet that what you suggest is possible. Simplicity is a most worthy goal.

I appreciate all of the posts thus far. Keep them coming.

[sheldon@dingwallguitars.com]

Alan O., I may be wrong, but I believe that only affects the canned Shopbot routines.

Alan S., if your parts need to fit together tightly, you will need to make test cuts and then re-do your part files. With the new Vector 9.3 you could create a new drawing for each offset and include the cutter diameter in the name. That will make it easier to go back. A pain yes, but I think we're out of options.

[gerald_d]

For the Alans, have a look at this thread (http://www.talkshopbot.com/forum/messages/22/137.html?1016749780#POST5674) from a few days ago.

Some bits are impossible to mic. Single and triple flutes for example. Rather cut a test piece and mic. that to see by how much it is too big or too small. Soon you realise that most jobs require only "tape measure" accuracy and that using a micrometer is a waste of time.

[asimpson]

Sheldon you may be correct. S.B. software is just following a path when the program is created in Vector. (I think) Therefore it does not care what cutter you are using. I was also thinking that the S.B. program would need to keep track of which side of the cut is the waste side and which is the part side to compensate correctly.

[asimpson]

Gerald I followed your thread and had pretty much guessed it spot on. I.e. my previous post.

I have read and read through the posts my head is spinning. I do not even have my machine yet. This pretty much answers this question unless someone else has more to add.

Be prepared for more of this type of probing questions from me.