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:

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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

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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.

Quote:

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Originally Posted by cropwell

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..

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The collet I'm using is a 3-4mm collet, so I would have thought that it would easily hold a 3.175mm bit. I haven't tried measuring the bit, but I will have a another test tomorrow and see.

Quote:

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Originally Posted by Kitwn

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

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Hi Kitwin, I'm using the same method I use for all bits I lower the bit onto a thin piece of paper and set it when I can just move the paper, but it's not pinched. Not the best method I know, but it seems to work well enough. I would love to by a zero setter at some point.

There are 4 categories of possible issues - electrical, mechanical, software, and 'user'.

I think with your experience that rules out user. As it is OK with other router bits that rules out electrical.

As it occurs with this specific bit then mechanical as other have suggested is possible, the obvious one being slipping up inside the collet. This can be checked by touching off before and after the cycle (paper is fine by the way). If it is this then get a 1/4" collet. Just personal preference but I always match the collet diameter exactly to the tool diameter.

The other one is software which should be considered further. I like Boyan's suggestion of copying a good tool in the library and editing the data to suit the faulty tool.

If that is no good then you can try cutting out a simple square in some scrap, one with tabs, and one without (screw the stock down through the square to avoid damaging the cutter when it breaks free). Ask for the usual 15.6 mm depth in a 15 mm part or whatever and see if the software is getting hung up on the tab part creating a bit of odd code.

I used a sister product called Vectric Cut2D many years ago but have long since migrated to F360, even so I don't remember anything like this.

Zip up the G-code file and post it. The G-code should tell you everything.? If it says 15.6mm in the code and you have touched the tool off correctly then the length of the tool makes no difference provided it's longer than 15.6mm and you have Z travel enough it should go through the material.! If not then it can only really be slipping in the collet because the other tools are cutting correctly so it's not a mechanical or controller issue.

I find Camotics useful for checking gcode https://camotics.org/

Thanks for all the suggestions guys, it's really appreciated as I've been stumped on this one, I will try some tests today and see if I can post the code here. I will try and set it up as another tool too and cut with and without tabs as when I did a test cut to half the depth of my material it was perfect!

Quote:

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Originally Posted by beemsquar2

Hi Kitwin, I'm using the same method I use for all bits I lower the bit onto a thin piece of paper and set it when I can just move the paper, but it's not pinched. Not the best method I know, but it seems to work well enough. I would love to by a zero setter at some point.

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My zero setter is a piece of brass bonded to acrylic. The brass/acrylic was turned on the lathe to make the faces parallel and a 4mm hole drilled in the brass for a wire to connect it to the BoB.

I have a macro for Mach3 which lowers the bit (earthed, in my case through the spindle) onto the brass and when it touches it retracts the tool 10mm and sets the tool to Gauge thickness + 10mm, so zero is top of material, bottom of gauge.

If everything weren't packed away whilst I am refurbing my workspace during lockdown, I could send you a copy of the macro and instructions, assuming you use Mach3.

Cheers, Rob

Cheers Rob, if you ever get it out again, feel free to send the macro, that would be very useful!

I ran a few tests today, but I'm still confused. I measured the bit before and after a cut, with and without tabs, it's definitely not the bit slipping. I had 19.06mm before and after. Out of the two cuts, the one without the tabs was better with only 1mm remaining, the tabed cut had 1.6mm remaining. I copied my whiteside compression bit, which I know works, changed the pass over and bit setup to match the 3.175mm bit and ran it again. Still no difference. I even tried making a pocket 11mm deep and it was perfect.
I am at a loss as to what is causing it!
I will try and post the G code tomorrow to see if someone can see any issues with it, but as far as I can tell its correct. I might try just for sanity sake to run the g code for the 3.175mm bit with my whiteside bit in a piece of scrap to see if that cuts through the material to the 15.6mm depth, which might rule our the code.
The only way I can get it to cut all the way through is to set the Z height at 1.6mm below the actual z height of the material, so I know it can cut through.

I was tired last night so I blaming that for not thinking of this before.!! . . Check the tool table to make sure you haven't got an height offset entered for that tool number. It's about the only other thing it could be if it's not slipping and the code is correct.

This is strange. If you want to post the Aspire file as well I can look into it. What post processor do you use? The Mach2/3 Arcs? I can generate another g-code with a custom mach3 post processor to check if it makes any difference.

Check if after finishing the job the Z0 is at the same correct height to rule out missing steps on the Z axis.

http://www.mycncuk.com/threads/8494-Touching-on

Here's the macro and how to install it and use it

I have the 2010 screenset and I'm very happy with it. I never switched back to the ugly Mach3 default design again :)

I find convenient the Tool Change tab. For each job I set the Material Offset to the material thickness and use the touchprobe on the table. This way I never cut through my spoilboard and the Z0 is automatically set to the upper face of my material. And the XY probing wizard is great as well.

Quote:

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Originally Posted by paulus.v

I have the 2010 screenset and I'm very happy with it. I never switched back to the ugly Mach3 default design again :)

I find convenient the Tool Change tab. For each job I set the Material Offset to the material thickness and use the touchprobe on the table. This way I never cut through my spoilboard and the Z0 is automatically set to the upper face of my material. And the XY probing wizard is great as well.

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I bought it as well (a while ago), I have not yet installed it. I have too much going on at the moment to take on any more change, but you are making me feel guilty:cower:

Quote:

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Originally Posted by cropwell

http://www.mycncuk.com/threads/8494-Touching-on

Here's the macro and how to install it and use it

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Thanks Cropwell! I'll look into this as as soon as I get more time.

Quote:

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Originally Posted by paulus.v

I have the 2010 screenset and I'm very happy with it. I never switched back to the ugly Mach3 default design again :)

I find convenient the Tool Change tab. For each job I set the Material Offset to the material thickness and use the touchprobe on the table. This way I never cut through my spoilboard and the Z0 is automatically set to the upper face of my material. And the XY probing wizard is great as well.

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I'll have to look into this, I've been the same as cropwell, kind of got resistant to change at the moment with so much going on. Looking forward to a quite period where I can try out some new things without forgetting something else!
I didn't get any time to look into my depth issue today as I had a ton of panels I had to get cut ready for glue up and hopefully oiling tomorrow.
I'll update soon.