Why are the depths so different?

[weaponx71]

Hello there, today I was making a sign for a Christmas present. Very simple, just some words. Fonts used were Times New Roman and Black Jack. Using VCarve Pro 8.5. Since the sign is prepainted, I used a scrap of the same wood and tested a few letters just to see if the fonts came out OK. The test piece came out wonderful. I set the depth to 0.125. I also have never used the 60 degree bit and was curious how it would do with the letters and a set depth. Anyway, the test piece came out just how I wanted. The bit setting is a 60 degree bit with 0.5625 width and a pass depth of 0.2 inches.
After the test went so well, I load up my sign board. Zero it out as I did the test piece and BAM... twice the depth on the letters than the test run. Why? Nothing changed. I even stopped after the first word, as it was the Times New Roman one and had larger letters, so wasn't so bad. But I knew that second set of letters in the Black Jack font would be very bad as they were smaller and thinner. Re did the smaller font just to double check everything was set, made a new tool path for it and the same result. Instead of the 1/8 depth, I got 1/4 inch depth on both sets of letters.

Only thing I could think of is when I made the test run, the board was smaller, but the lettering area was bigger, so the letters are about 1/2 an inch taller. But I was baffled by this as even if the letters are smaller the depth shouldn't have been affected, and the preview in the program looked the same for both jobs.

Any ideas? I have two more chances to get it right and a few days before the gift is being given.

Thank you

[Adrian]

The size of the letter does affect the depth of a VCarve as does the angle of the bit you use. The close the inner and outer vectors are (smaller letter) less of the bit can fit between between the vectors so the shallower it cuts. The wider apart they are (larger letters) more of the bit can fit between them so the deeper it cuts.

If you want an exact depth on a VCarve then you have to specify a flat depth otherwise the depth is always a function of the inner/outer distance and the angle of the bit. To see how deep a VCarve toolpath cuts you can hover the mouse over the toolpath in the toolpath list and a pop-up will appear showing the max depth.

[weaponx71]

I did specify a flat depth, both were set at 0.125.

[Rcnewcomb]

The preview looks correct on both files and both show a max Z depth of 0.125". If the preview is correct then you are dealing with something else outside of the Vectric software.

Did you Z-zero to the top of the material as specified in your files?
When you move Z back to zero was it at the correct position or did your Z axis lose steps?
Is the bit slipping in the collet?
Is you material flat?
Is your hold-down working properly?

[adze_cnc]

If you look at the file you sent to your machine is the Z-depth for the cuts -0.125 or some other value?

[weaponx71]

Rcnewcomb - I checked all that you listed when I made the cuts. I actually did move back to zero on both cuts as for some reason when I loaded the tap file, can chose Run, the Z didn't move to it's normal starting Z height. Usually it defaults to 0.530. So I shut down the Shark program and reloaded the file, and in doing so I double checked that the Z - 0 spot didn't move.

Adze_cnc - I just now checked the tap files and both are listed as -0.125.

It just seems to me that when I moved to the sign, it forgot that I had a depth set. So maybe it is the Shark program to run the G-Code.

[Adrian]

I did specify a flat depth, both were set at 0.125.

Sorry, I was on my phone so couldn't download the files and from your description it was the most likely explanation. If the depths are correct in the toolpaths within VCarve then, as Randall says, you're dealing with something outside VCarve.

[tonydude919]

Why is your cutting parameters of the 60 v bit different between the 2 files? Take a look at it.

Tony

[weaponx71]

Adrian, yes, thank you, I am thinking it must be in the shark program as well. When I get a chance again I will make sure.

Tonydude, not really sure. The first one might be the original that I had on my laptop, and the second one is probably from the cutting machine laptop, as I had to put in a new cutting tool for the size of bit I had so I just copied the 60 degree one that was already there. I never made any changes to those numbers for this job.

I normally use the center point for the zero point, but this job I did it in the lower left corner. My next attempt I am going back to the center. And I will be making the sign over again from scratch directly on the cutting laptop. I had made the sign on my own laptop then just transferred the file over. I guess I am out of ways to test this besides also watching the cutting program when it zeros out this time very closely.

Thank you all for your help, was just wondering if I had missed something between the two jobs.

[tonydude919]

If you hit the upper limit of your z, than that will throw off your depth too.

Tony