Precise (!) Z adjustments

[FredJuergens]

I just acquired a Shark Pro +, and I'm a newbie to CNC woodworking. I have to engrave 140 individual walnut plaques with names of donors to a building campaign. The plaques will be on display in the completed building for the next 50 years or more. I want the engravings to all look as nearly the same, so far as the font goes, as possible. The workpieces will all be planed to as close to the same thickness as possible. The font will be Times New Roman, 0.400" high, and I expect to use a 60 degree included angle V-bit.

In preparation for this project, I've discovered that small variations in positioning the tip of the bit at the top surface of the wood (the Z direction) leads to noticeable differences in the width of the strokes (especially the thinner sections) making up the individual letters. It appears the the gentlest "jog" by tapping the Z- or Z+ button on the NewWave softtware moves the bit up or down by some 0.020" to 0.030", much more than I would like to tolerate in starting position. I've read on this forum that slowing down the FRO speed while jogging can reduce the minimum jog. (I've not had a chance to actually try this method yet, but it seems like sort of a kludge.)

So,... is there another way to lower the V-bit in increments of 0.003" or less until it just kisses, say, a thin metal feeler gauge placed on the wood surface? (Metal has to be a better gauge, I think, than the paper suggested in the Shark set-up pamphlet.) If there is another way, I think this would allow more uniformity in the letters I intend to engrave. (And if so, the technique should be described in future editions of the pamphlet!)

All input is welcome. Thanks!

[RhB_HJ]

Hi Fred,

How about moving it really close to your reference face (feeler gauge) "zero"the Z-axis, then use the feeler gauge to measure how far you're from the surface of the workpiece. Off set to get to within exactly .050" and measure again to double check. Of course that's strictly my theory as I'm not that far yet. Should be able to off set exact amounts rather than just jogging.

[zac]

Hi Fred.
Leave the bit loose in the router collet, lower the "Z" to very close to the surface of the timber, loosen the collet until the bit touches the timber,tighten the collet and zero "Z"
Wayne

[CountryWoodCrafts]

Here is what I do . . . .

I get the X and Y positioned . . . .
Turn off the controller with the red button. . . .hand twist the Z screw down . . .(unlimited control over the distance)
When where you want it turn the controller back on . . .
When the controller comes back up it zeros out to 0,0,0
It even keeps the file uploaded in the basic panel. . . I have been doing this for a while now. . . .
I got tired of putting dents in my freshly milled and sanded wood

Wayne . . .the only problem I have found in doing it like you do is when you tighten the collet the side play while tightening will push the bit up and if you take another measurement after it sometimes (not always) goes off by .001 or .002 . I thought it was a great way too but when changing from vbit to straight (for a clearing path) cutting on the same plane there can be height difference of a thou or two and it shows big time . . . the way I handle it the difference is much smaller.

[FredJuergens]

Thanks for the suggestions, guys! I'll be trying them out this weekend to see which works best for me. And I'm still open to other ideas as well. Once I settle on a method, I'll try to describe it in a post.

---Fred

[RhB_HJ]

Yesterday I finally got to play around with "things", the smallest increment in jog mode is .040". It actually repeats very accurately until it throws in a .039 step and then goes back to .040"' steps. Hmmm could that be a Metric leadscrew? something else to check.
Measuring with the feeler gauge or gauge blocks (aka joe blocks) should work just dandy. Off set the corresponding "0" accordingly (+ or -) , this will also work for the "Y" axis which is not as readily accessible to turn manually.

[REG]

Here is what I do . . . .

I get the X and Y positioned . . . .
Turn off the controller with the red button. . . .hand twist the Z screw down . . .(unlimited control over the distance)
When where you want it turn the controller back on . . .
When the controller comes back up it zeros out to 0,0,0
It even keeps the file uploaded in the basic panel. . . I have been doing this for a while now. . . .
I got tired of putting dents in my freshly milled and sanded wood

Wayne . . .the only problem I have found in doing it like you do is when you tighten the collet the side play while tightening will push the bit up and if you take another measurement after it sometimes (not always) goes off by .001 or .002 . I thought it was a great way too but when changing from vbit to straight (for a clearing path) cutting on the same plane there can be height difference of a thou or two and it shows big time . . . the way I handle it the difference is much smaller.

I will confess I tried this yesterday and it works wonderfully! I am making some small, tight engravings with a 1/4", 45 degree bit on 1/4" cabinet grade maple and the thickness will vary a little from one end of the sheet to the other. So, zeroing my Z axis would come off a 32nd and there is no way I am going to get that in the jog even with FRO at minimum. Turning the screw really helped make this project a lot easier!!

Thanks for the tip!!

[Dwayne125]

Happy Hollidays

Can this method be used on a Shark, or Shark Pro? I know the Pro+ has the red emergancy stop button, but the other sharks do not. If this can be done on the others, can someone please explain how?

Thanks
Dwayne

[CountryWoodCrafts]

That I do not know. . . I have the Pro Plus Modified. Do you have an on/off switch on your controller? If you do you could experiment like I did with the red button and load a file . . .move to your x and y then turn off your controller and hand screw down the z and turn the controller back on . . .by right it should fire up connect the usb link and show in your basic panel as x,y,z 0,0,0 . . . . and the file since the basic panel is still open on the computer should still hold your file as well . . .

[Buc]

Here is a link for an idea on an on/off/E-stop switch. http://www.woodshred.com/asharkpowercenter.html
I have a Shark Pro and it works for me.
Buc