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[Stickman]

Odd. I just tried to post a reply and it looks like it disappeared ...?

Anyway, HELP! I'm having a problem setting up to carve in .25. PVC just won't accept an engraving bit as the depth exceeds the cutting parameters of the tool (max dept is .104). I tried using a tiny ball-end but the preview was absolutely useless, then I set up the 30° engraver as a v-bit, and the lack of detail visible in the preview was terrible compared to what I could see in my previous efforts.

[calgrdnr]

I tell PVC that the material thickness is .25" . I set a max cut depth at .21 . setup with a cut angle of 315 deg and 10% line spacing using a .031 dia ball nose, but actually chuck up a .25" 30 deg v-bit and cut it all in 1 pass and have had excellent results.

Read what mike says ...


the reason for 315 degree is so the bit doesn't have to cut a lot of material at start. i.e it basically makes a hole then works it way out from there at 10 % of bit size you chose. if you run at 12.5 degrees it it will cut a line at 12.5 degrees to the other side of your carving this will put a lot
more stress on the bit then starting with the hole ....
as stated before if you follow my direction you will not see any machine marks .... is no need to try
hide machine lines with the suns rays

[Stickman]

I actually have a .0313" ball-nose bit from Precisionbits.com, but I'm still learning how to set up the bit profiles. For instance, my 1/8" 30° engraver is showing far fewer lines than the ball-nose, though it has a finer tip, and of course it won't calculate it at .2 depth, obviously the reason for the deception of using the ballnose. I'm not sure if I'm setting up the flat surface correctly on the engraver. Vectric's help isn't too explanatory; the picture looks like it's the width at plunge depth.

As for the 315° angle, I imagine it could as easily be 45°, 135° or 225° to get the same cutting action. Am I missing something? Regardless, even when I cut at 12.5°, the program always starts in a corner and the first cuts are very short, creating that "hole". Of course I'll have to see how much difference there is cutting deeper material. I didn't cut that angle to hide machine marks, since I was getting excellent results with the 30° bit. It just seemed in the preview to bring out the play of light and shadow better that way, though I don't discount my imagination playing a part in that perception.

Does it make any difference to the bit, though? Or is this to more evenly distribute load on the stepper motors? Since the Y-axis is moving much more mass than X, there's more vibration on the table. Now that my machine is working as expected, perhaps that isn't an issue. I was having controller software problems for quite awhile, and didn't know if vibration was causing the machine to lose steps (though the controller and power supply are not on the same table as the machine).

Hopefully I'm not sounding argumentative, just trying to decipher what is significant out of all the parameters I'm learning.

[MikeUSNRet]

Here's a screen shot of my setups for a visual. We cut at at 315 deg. After the initial hole it puts in the lower left corner, you will be only shaving .003 at a time off. Sure, you can cut at 45 deg also, but although it doesn't seem like it, it will put more stress on your bit and if you cut at a higher feed rate, you have a greater chance of breaking the tool. don't know about you, but I don't have a lot of $21.00 bills (or more depending on where you purchase) laying around to keep replacing bits.

Oh yea..and on the material setup page where you set in X and Y, I set Z0 at the top of the material and enter in .21 for the thickness.

And also notice on the Tool Database screen where you enter tool paramaters, Notice that I set the pass depth as .21 also.

[calgrdnr]

As for the 315° angle, I imagine it could as easily be 45°, 135° or 225° to get the same cutting action. Am I missing something?

You are correct same cutting action except 315 will start cutting at x0 , y0 this way if it should screw up you have less material lost. if you cut at 45 and your carve size is x4 inch y4 it will start at x4y0 if it screws up
you lose the area from x4-x0 does that make sense

as far as mechanical stresses you will need to talk to an engineer .. I am just a hobbyist who has figured out a way to make decent lithophanes I have yet to break more then the tip . and I can understand that as it is like a needle at the very end.

[Stickman]

That looks a lot like the setting I put together for my .0313 bit earlier today. At first I thought from the diagram that the diameter was the shaft of the bit, but that wouldn't make much sense, would it? Meanwhile the speeds and feeds are a bit arbitrary for me, since my Bosch Colt just hums along at whatever speed I think sounds right. I'm waiting (and waiting ...) for my new machine that has a spindle which fully utilizes that part of the program.

[Stickman]

>You are correct same cutting action except 315 will start cutting at x0 , y0 this way if it should screw >up you have less material lost. if you cut at 45 and your carve size is x4 inch y4 it will start at x4y0 if >it screws upyou lose the area from x4-x0 does that make sense


OK, you've got me scratching my head on this one. It might just take me more time on the machine to realize what is really going on. In my mind, regardless of which corner you start from, if the project messes up at some point, say 10% of the way through, the same amount of material would have been cut. The only difference I can see is if the machine has to jog to a start point or not, which shouldn't affect the cutting once the z-axis goes down.

[Stickman]

After sleeping on it this makes sense if one is carving out of a large piece of material. I've been cutting mine to size before carving, so if I ruin the piece, it's the whole thing.

[fretsman68]

That Centurion bit looks like the 10 I'm getting for the same price from China. If they last 1/10th as long, it'll be a wash. So far I've cut 3 pieces with one half-round bit (cut flat on one side, round taper on the other side) and it's still very sharp.

Agreed, and Centurion wants $8.79 just to ship to PA (USA) for 1 1/2 90 deg. cutter.

Dave