Using the start depth option

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Using the start depth option

Postby cusoak » Tue Jul 02, 2019 1:02 pm

I make some plaques that I use a 90 degree vbit at a plunge depth of .3 of an inch to create a bevel on the outer edge after it is cut out.
Right not I use a .25 end mil to cut the finished piece out.
The bit cuts some air first.
I want to change the bit to an .125 end mil
After I simulate the vbit cut how could I tell how far down I could set the start depth so that the bit won't cut air.
I use a ramp in for the cut out path.
Could I stick my cursor into the V and read the depth.
and use that as the start depth.
Thanks Jeff
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Re: Using the start depth option

Postby TReischl » Tue Jul 02, 2019 1:26 pm

Draw a side view of it to scale, that will show you what is going on. Like this:

Capture.JPG


Or, if you are cutting right on the point of the V groove you could subtract the bit diameter from the depth of the cut made with the V tool. That only works with a 90 degree bit.
Last edited by TReischl on Tue Jul 02, 2019 1:28 pm, edited 1 time in total.
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Re: Using the start depth option

Postby Adrian » Tue Jul 02, 2019 1:28 pm

As you've said the best way would be to hover your mouse over the area where the endmill cut the profile and set the start depth to that. Remember to allow for the diameter of the bit so you get the highest part of the v-bit cut.
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Re: Using the start depth option

Postby litzluth » Tue Jul 02, 2019 3:50 pm

OK Ted, I know you had a great geometry and trig teacher in high school. You can check my work. This excel equation is intended to give the elevation you would set, based on the bit diameter entered and 1/2 the v bit angle.
I can't seem to upload an .xlsx file. To get the file to work in excel, you will need to rename it with an .xlsx extension. You then plug in the appropriate numbers in cells B3 and C3, and it gives you the answer in cell F3.
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elevation based on profile bit diameter and v bit angle.pdf
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Re: Using the start depth option

Postby TReischl » Tue Jul 02, 2019 10:33 pm

litzluth wrote:OK Ted, I know you had a great geometry and trig teacher in high school. You can check my work. This excel equation is intended to give the elevation you would set, based on the bit diameter entered and 1/2 the v bit angle.
I can't seem to upload an .xlsx file. To get the file to work in excel, you will need to rename it with an .xlsx extension. You then plug in the appropriate numbers in cells B3 and C3, and it gives you the answer in cell F3.


Missing one important piece of info: how deep did the v bit actually cut?

You wouldn't want to tell it to start cutting .25 when the V bit only went .125 deep total, right? Yea, I know, things like this should be used with at least a half ounce of common sense.

Other than that, the formula works correctly.
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Re: Using the start depth option

Postby litzluth » Wed Jul 03, 2019 6:03 pm

To Ted's point, if the elevation computed using the Excel formula exceeds the height of the v groove, you have to plug in a smaller diameter bit in cell b3 until the elevation result is less than the depth of the v groove.
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Re: Using the start depth option

Postby cusoak » Sat Jul 06, 2019 12:48 pm

Thanks I got it. and more . I would not of allowed for the dia of the bit.
Thanks Jeff
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