Router bit not milling full depth

Hi all, Im new to the forum and have been CNCing at a hobby level for a few years or so now using a semi professional setup purchased from Marchant Dice (Unfortunately).
I use Vcarve pro, Sketchup and Mach 3 for all my designing and CAD/CAM software.

I have a problem at the moment with a router bit I have that just will not mill the full depth I set it too. I am mainly cutting Baltic Birch ply at the moment and have been cutting out some inset doors using a 3.175mm compression spiral bit, this will not cut through the material no matter how many times I've changed the cut depth in Vcarve on the toolpath even when cutting deeper than my material thickness, It only seems to cut to the top of my tabs which are set to 1.8 mm. when I switch to my Whiteside 0.25" compression bt for cutting my external cuts I have no problems, nor do I have any problem with any other bit I use.
I can't see if I have set the bt up wrong in Vcarve, so was wondering if someone could possibly offer some guidance in what might be the cause of this?

Any help would be much appreciated!

Cheers

Andy

How it would not cut? If something does not cut then the machine pushes it down and it will burn through material and break. So obviously its the CAM. Or the bit slips up in the collet. Or you have a backslash of 3mm, but still...

In V carve there is a Start depth and Cut depth. Set this right. Check then the tool itself from the toolpath window as there you can edit passes and so. If all is right there check your Material setup from the tool[ath window, where you set the safe Z and so.

I am looking from Aspire, but in V carve should be the same or similar

Quote:

---

Originally Posted by Boyan Silyavski

How it would not cut? If something does not cut then the machine pushes it down and it will burn through material and break. So obviously its the CAM. Or the bit slips up in the collet. Or you have a backslash of 3mm, but still...

In V carve there is a Start depth and Cut depth. Set this right. Check then the tool itself from the toolpath window as there you can edit passes and so. If all is right there check your Material setup from the tool[ath window, where you set the safe Z and so.

I am looking from Aspire, but in V carve should be the same or similar

---

Thank you for your quick reply.
The cutter cuts perfectly, just not to the required depth set in v carve, start depth is set identically to all my other bits at 0.0mm cut depth is set the same as my other bits at 15.6mm to cut through 15mm ply. ( I don't know why, but this depth seems to give me the best finish on the underside and still retains my tabs.
As I say, even if I increase the cut depth to 17mm, it still cuts to just above the tab depth. It is only this router bit I have this issue with, which is odd.
The diameter of the bit is set correctly in v carve at 3.175mm, as an end mill, there is no option to input cutter length. Pass depth is set to 2.8mm, step over at 0.952mm at 30%

Passes in the tool path are set at 5 passes comprising of 3.333 for the first cut and then 6.24, 9.36,12.48 and 15.6mm. As far as I can tell this is all set correctly?

Safe Z is set at 6mm above the workpiece.

Any help with this extra info would be appreciated.

Many thanks

Andy

Why dont you save a new bit with all the data from this one and try to see what happens? Copy one of bits who works and then edit the data.

How are you setting the tool height?
Have you tried to manually jog to that 15.6 mm depth? Is it possible that the tool is shorter than the other ones and you reach the end of Z axis travel?

You can scroll the g-code to the end part where it cuts at full depth to see if it has the Z-15.6 or Z0 or Z-0.6 command, depending on where you have set the the Z0, on top surface of your workpiece or on the surface of the table..

Hi Paul,

I have tried to jog the machine and I can manually jog the machine with the bit and z set to top of material to beyond th 15.6mm depth by another 27mm You might be onto something though, as it is the shortest bit I own and have tried to cut all the way through my material.

The gcode has the lines to suggest it is cutting to 15.6mm and 13.8mm, which I guess is the tabs and the final cut depth?

I just tried setting the z a little bellow the top surface to see if it would cut deeper and I did along some of the part and then went back to being above bottom of the panel surface. I wonder if there may be some slippage with the collet, so I may look at this now. It's a 3.175mm mm bit in a 3mm collet, but maybe as the bit is shorter it is only holding at the end of the collet? I don't have this issue when using my 3mm engraving bit, but then I'm only milling a few mm into the top surface. The next collet down is a 1.5-2mm collet, so it may not fit.

Thanks for your help guys, unfortunately the plot thickens.

From what I know, it is not allowed to put a bigger tool diameter in the collet. You can put the 3.175 tool in the 4-3 mm collet (even if it is not recommended) but not in the 3-2 mm one.

I never tried it myself as I have a set of metric collets with 1 mm increment plus the 1/2, 1/4, 1/8 inch ones.

Most of my tooling is 1/8th, so I have a 1/8th collet - Simples!

Have you measured the tool stick-out before and after cutting? a 1/8th tool in a 3mm collet may just not be gripping properly, especially if it is not fully inserted in the first place..

What method are you using to zero the Z height before each cut?

This is bonkers. Can't wait to see what's causing it... Full disclosure, please...

Wal.