How about doing an air cut.

[ElderlyGent]

HI all,

I recently had a very narrow escape from a disaster. I had set the work piece up with screw hold downs that looked to be well away from any toolpath. So using a 1/8th end mill I started cutting the outer toolpath to release the workpiece, Now I, for now. being a bit of both a newbie to this CNC stuff and a bit nervous, I had set the feeds and speeds to as slow as seemed ok .
The cutter strted of fine, but as it neared one of the hold downs I thhought, OH CRap. its going to hit..I hit the pause button and nudged it forward. OK in tyhe end it missed the holddown by a fraction, so all was well.

But it was a fraught moment for all that, So my question is,,,,,, HOW TO DO AN AIR CUT,

I see no tutorails about this, so perhaps one of you nice techies can point me in the right direction.

Best to all out there

EG.

[WNC_Ed]

Easy way would be to set your Z-Zero to whatever height above the actual surface you would like to run it.
Bear in mind that if you are doing the whole tool path in the air then make sure your higher than your material thickness so the deepest point of your air cut is still above your surface.

[dealguy11]

Maybe I'm not understanding what you want to do, but wouldn't the easiest way to do it be to just run the program without any material in place?

[jimwill2]

When I'm using screws to hold my project I always create a toolpath to put the screws where I know they will be safe. I put a couple of clamps on the piece while I cut the screw-holes... then screw it down and get started. If I'm cutting inside profiles I also put screws on the inside off-fall so I don't need tabs.

[scottp55]

+1 on Jim's method.
Shown here in more detail by Shopbot's TJ at minute 24:40;
https://www.youtube.com/watch?time_cont ... jdfg4e1IE8

Back when I used screws, and barely knew anything and did a lot of Air Cuts....I kept 4 .25" sandstone coasters next to machine....I'd hover over the toolpath that had me worried, and note the Max Depth...then select a combo of coasters that was THICKER than my toolpath's Maximum Depth, stick my Z-Zero plate on top of those..and Z-Zero as normal.

NOT familiar with your machines software, so can't tell you the easy way to do it in Shopbot's software....BUT there usually IS a way to avoid using spacers and keep the bit in for good visualization using your machines software.

Use Jim and TJ's method if you're just trying to not make custom screw heads
scott

[ElderlyGent]

Many thanks guys. I appreciate, as I am sure many others do, all the help we get on this Forum. Now to sort out which one to use.

[martin54]

I see no tutorails about this, so perhaps one of you nice techies can point me in the right direction.

It would probably be quite difficult for Vectric to produce tutorials for something like this as it is done through your machine control software. People on the forum will be using Different Control software & they all do things differently The tutorials concentrate on the Vectric software as that is what Vectric know best

Different ways this can be done, some mentioned above. Setting your z hight at a level above the material surface is generally how this is done, if you are just wanting to check the perimeter then it is easy to set up another toolpath with a very shallow cut depth to do that.

Some people don't worry about it, they use plastic nails for hold down & if they get hit it doesn't matter, think this is probably a more expensive option though as cost of equipment would need to be taken into account. I use wooden clamps quite a bit rather than screws but my machine bd has T tracks that allow me to use clamps