Tricking up the Z height

[tlempicke]

I was just perusing the thread about creating inlays and was interested to see that the author discussed varying the Z height just a few thousandths.

I have come across several instances where I would have liked to be able to zero the cutter to the material and then raise or lower it a few thousandths. For instance to run a second cut to clean up fuzzies.

Would it not be nice if we had some simple way to do this? Maybe I am just not smart enough to find it.

I have done this in the past by moving the cutter off of the work piece and setting it to zero, then moving in a negative direction, then using the z zero command.

is there not an easier way that does not involve moving the cutter off of the workpiece?

[Brady Watson]

I have done this in the past by moving the cutter off of the work piece and setting it to zero, then moving in a negative direction, then using the z zero command.


You can do it this way, or use the VA command to assign a location to where the tool is currently sitting. So, if your Z was sitting at 1.00", you could type in VA and enter in 1.01 and the Z will cut .01" deeper on the next pass. It's a little confusing at first, but works well.

-B

[scottp55]

Tom,
Also a tip I got here was to run the same toolpath twice. It works great.
Because you're not actually cutting anything, just "duplicate" the toolpath and then "edit" the bit so that it can do a full depth pass and speed the feed up.
For instance, yesterday I did a new design with a .125"60degree engraving bit. First pass was actually cutting Purpleheart so it was 1,.5,16K. So I duplicated the toolpath and edited the name to 1B Speedpass, and edited feeds to 3,2,17K and it cleaned up all the cuts Fast! It came out almost burnished:)
Darn, with forum change it won't take bigger pics:(
Also, not seeing preview of attachments like I was? Is there a setting I have to change? Only happens since Nancy "improved" forum:(
Hope this helped
Play with it.
scott

[scottp55]

Brady, You didn't mention "Nudging" ? Or was .01" too much?

[srwtlc]

Move Nudge (MN). Adjust +/- up to 0.5" per axis.

[gundog]

You can zero any axis at the current position by entering ZZ for zero Z at the current position or ZX, ZY for those axis, you get the idea. Type Z2 and it zeros X & Y at the current position Z3 does all axis at current position. In your case you could MZ to 1.01 and when it moves there type ZZ and enter. The VA command can do the same like Brady explains works also.

Mike

[David Iannone]

Brady, You didn't mention "Nudging" ? Or was .01" too much?

I have used the nudge feature in certain situations. Although it may not be the best way to do it was the only way I knew other than the move off table and re zero z.

I restart my file then immediately pause. Nudge z down whatever I want it. Then resume.

But beware, this can get you in trouble if for instance you put a new piece of material on table to cut with same bit and forget to re zero z to the original height of material/table base etc.

Dave

[MogulTx]

I have used both the Nudge (actively, during a cut where the material may have varied a little and I wanted the bit deeper by a small amount) and I have modified files like Scott suggested, where I strip out all the layers except the final cut level. And I will sometimes put in different speeds.

One other thing that I do with a lot of my files is to look at the position of my gantry after the cut is finished. If I want to have free access to take my part off the machine, I will modify the file to send the gantry far enough down the machine that I can take off my parts. ( I run a 5 x 10, so some of my parts are pretty good sized, and clearance is a must.

And something I started doing about 6 months after I got my first ShopBot was that I actually program in points to insert screws, if I am going to use them. Previously, I was always trying to envision where something was going to come out of a sheet or dimensional lumber, etc., so I could put in a few screws to hold it. And it finally dawned on me that I have the perfect tool to tell me where to place screws! Aspire is my friend, if I will open up my perception and figure out what it can do for me. ( I don't have enough power in my "barn" to run the Vac table, sadly enough! Some day....)


Monty

[gundog]

You can zero any axis at the current position by entering ZZ for zero Z at the current position or ZX, ZY for those axis, you get the idea. Type Z2 and it zeros X & Y at the current position Z3 does all axis at current position. In your case you could MZ to 1.01 and when it moves there type ZZ and enter. The VA command can do the same like Brady explains works also.

Mike

Disregard this it would make it .010" too high do as Brady says with the VA command. In order for what I told you to do you would have to send the bit into the material by -.010" so unless you have a pocket this is not the way to go use your VA command. Sorry for the misinformation it dawned on me when I went out to my machine and started getting things set up.

Mike

[tlempicke]

You can do it this way, or use the VA command to assign a location to where the tool is currently sitting. So, if your Z was sitting at 1.00", you could type in VA and enter in 1.01 and the Z will cut .01" deeper on the next pass. It's a little confusing at first, but works well.

-B
This looks like exactly what I want, but it is confusing to me. Can you explain the "thinking" that the program is doing?

[BrandanS]

This looks like exactly what I want, but it is confusing to me. Can you explain the "thinking" that the program is doing?

It's not so much "thinking" as you are tricking or forcing the Z-Axis to be whatever you want it to be. If you want to 0.010" deeper on your next run, move your Bot to a value friendly position (such as Brady recommended 1.00"), [VA] and "force" this position to now be 1.010" (ie. that 1.000" position will now read 1.010" on the readout.

Imagine if you were, from this new 1.010", to tell it to go MZ 1.000", how would the Z-Axis react? Well it would move DOWN from 1.010" to 1.000" thus you've now OFFSET 0.010" from your previous toolpath.

--Brandan R Smith

[jerry_stanek]

I use the nudge to do this. If the job is running and I hit space it gives you a option to nudge x y z or I will use the MN command to get to the nudge. I have also used Brady's method. All seem to work

[srwtlc]

This is the manual way of what Move Nudge (MN) does. If your Z is at 1" and you do move nudge and click the down arrow for the Z axis until it reads -0.01 and hit continue, it will move down 0.01 and reset Z to 1". With the VA command, you are leaving the physical position of the Z alone, but telling the software that it is actually at 1.01. With this scenario, if you then commanded the Z to go to 1", it would now be in the same place as it would have been with the previous move nudge scenario. Move nudge takes the thinking out of the VA fill-in sheet. ;) You can use it before you start a file or during with spacebar/insert/nudge.