If you have a 3.5" thick piece of wood, I think you are about at the limit switch setting by just skimming the bit across the top edge. The problem is not with .25" depth you're cutting, but the fact that when the bit rises to its initial start point it's already hitting the limit switch.
If you're saying you have a 3.5 x 3.5 x .25 piece of wood, and that your starting point is at the .25" top face, and then the bit retracts too far up and trips the limit switch, then it's obviously something in your settings in ArtCam or ipicture. I don't know Artcam so I can't help there, but check the dimensions you have for Z in ipicture before converting to a gee file. I know sometimes I've gone in and made a change and it didn't clear the default setting, just added my numbers to the default.
I'd be interested in hearing how the problem gets solved, but I'm guessing it's in the setting and not necessarily in the machine.
I believe the limit for thickness of material is 3 inches. This accounts for the length of the bit and the total amount of up and down Z axis travel, so I think that is why you are hitting the limit switch.
On the 1015 you can go max 4.13". The issue was the bit I was using was 3" long which was kicking the limit. I put in a 2" long bit and it worked (just barely) so I'm thinking the 4.13" clearance on 1015 is more like 3.75"
On to the next issue...I just started using Cut2D and I was wanting to set up my R1/50 and R1/32 Conical bits in the tools database. I thought I saw that one of you guys used it. How do I determine the values for the tool bit in the setup?
I am not using any program other than I-Picture as I have the 1013 model. But some info on bits geometry are as follows: 1/32" bit 2.36" long 1" cutting area 5.5 degree cutting angle
1/50 " bit 2.36" long 1" cutting area 4.82 degree cutting angle
Thanks Bob! That will help a lot. I actually have not used I Picture much but will have to mess around with it. I've been using Artcam that came as a package deal with the the 1015, but can't register it now because Oliver sold the rights to another company. Just started using Cut2D which is pretty cool and easy to use. I use my CNC mostly to build parts. I've seen a lot of your work...Excellent job!