Tool Plunge

[rickbw]

I have a SB Desktop purchased in late 2011. Haven't been able to use it for awhile but just recently set it back up and ran a couple test projects without any issue. So I figured I would try a bigger project and decided on the "Crazy Heart" from vectric. So I loaded the file into Aspire 4.5 and re calculated all the toolpaths and saved them into .sbp files. I took double sided tape and held down a 7" x 10" piece of sapele. Put a 1/4 spiral cut bit in the SB and zeroed my X & Y and then zeroed the Z to the top of the sapele with the aluminum plate (as it is in the Crazy heart file from Vectric).

I then ran the inlay toolpath and the SB moved to XY zero then to the inlay point and proceeded to raise the spindle up and then plunged into and thru the sapele into my MDF board. I quickly hit the space bar and quit the cut.

I can't figure out why the spindle would have done that. I went back to Aspire and checked everyting I could think of
- Start depth is 0.0
- Cut depth is 0.25
- I re checked the Material setup and Z is set for the top of the board

The only thing that I can possibly think of is the safe Z and home position for Z? So I've attached screenshots along with the actual toolpath.

If anyone could take a look or point me in the right direction, I would appreciate it - I don't want to wreck anymore good wood :(

Thx!

[steve_g]

Rick…
Your .sbp file only cuts .25 deep… Apparently the zeroing to the top of the material didn’t take…
Try again in the air somewhere.
SG

[rickbw]

Thanks Steve,

So I went back to the SB and looked at the SB3 software position window & hit 'k" to pg down - sure enough Z zero was at the MDF level..... strange, I could have sworn I looked after I zeroed with the aluminum plate previously and it was OK.

So I then put the piece of sapele back on the MDF (figured it was already cut thru and no good anyway) & I then ran C2 & zeroed to the sapele. I re checked the SB3 software positions window and Z zero was at the top of the sapele. So I figured I would give it a shot.

Ran the file and ......... SB moved to XY zero and then to the profile position raised the spindle up (note below) and bang, same thing happened, the spindle plunged thru the sapele into the MDF.

However, note that when the SB raised the spindle up (prior to plunging into the wood), it obviously went as high as it could go and I could tell something was wrong because it actually almost seemed like it wanted to go higher (seemed like it shook at the top of the hieght).

I then checked where Z zero was after removing the sapele and it had moved to the top of the MDF. Obviously something is happening when the spindle goes to the profile position and then raises itself up before plunging into the cut. Any ideas?

[adrianm]

How much Z movement have you got from where you're setting the Z zero to the top of your z movement?

You've got the home Z set to 2" which could be too high causing the Z to hit the top stop and lose it's position.

[scottp55]

Rick, Like Adrian said---You topped out when it went to home position, and lost Z position. 0 was at .76", plus 2.0" for home position, PLUS length of bit extended.
Looks like your home position is still the Vectric default. Change Home position to .5-1.0" or your safe Z height. Insert bit into collet what you need for the cut plus .25" or on longer bits-as far as you can(until it tops out and back off a 1/4") on smooth shank.
Unless you have clamps or material that is higher than your workpiece, .5" works good for a safe Z and the Z-2 value can be almost nothing, but .2" should be quite safe(we use 10% of safe Z).
DON'T FORGET!! Check all your files! Most will probably be that if you haven't changed it. Recalculate ALL toolpaths and resave .SBP's.
I did it when I first started and almost hit my extrusions just trying to rabbit my spoilboard.
Doesn't affect most people as they have more Z than us. Be cautious of any file you get from someone else unless it's a .CRV so you can check and adjust Home and safe Z.
2 days ago I was cutting on the fly and my last file I made was zero'd from the spoilboard and safe Z was set at 1.7" as well as safe Z. Thank G for upper Z prox switch as when it tops out it just stops! Of course I had 2 people watching (prepared to be awestruck:)) and it took me 3 times to figure out what I had done. VCP remembers setting for last file you made.
Don't get discouraged! E-mail me if you want to.

[scottp55]

Just reread. That NOISE is a hard stop! ANYTIME you hear that---STOP!
You will have to re-zero whichever Axis hit(probably best to do all).
Horrible Noise- Ain't it?:)

[steve_g]

“Doesn't affect most people as they have more Z than us”
I don’t think I’ve ever hit the top of my Z axis travel and so don’t think about that!
What Scott said!... “That NOISE is a hard stop! ANYTIME you hear that---STOP”
SG.

[scottp55]

Just a note Rick. If you had been watching your #'s you would have seen the #'s increasing even though your spindle had stopped rising. Same thing with X,Y. Pretty funky and you know something's wrong when your X,Y position on a Desktop is 36,24 :)

[rickbw]

Well, thanks everyone for your inputs. The issue was definitely the Z height. I had my bit protruding too long from the collet & then I changed Z positions in Aspire as suggested & everything worked fine. The spindle never rose up and shook! :)

From now on when that happens (hopefully never again), the space bar will be my next quick move!

Thanks again!