what is creating this cut?

[charlieuk]

still working on this project and doing test cuts as I still have a lot to learn! I'm a bit baffled as to what is creating this little cut that is right on the edge of the small channel?  any suggestions would be great!

[LibertyMachine]

It appears to me that your Z axis WCS is off or your tool touch off needs to be re-examined. Your toolpath is going right to the top:

If both your WCS and your tool offset prove to be correct, you can go into the operation and go over to the Heights tab. For your Top Height, give it a negative offset of the radius of the ball endmill (-3mm) and it will only go up to the apex of the tool:

[LibertyMachine]

And you have it on both sides, no?

[charlieuk]

hi sorry I'm a bit new to this what do you mean by wcs? yes it is on booth sides of the outer channel however looks ok on the main cut.

I'm manually setting the Z 0 using the paper method and then going down .005 after leaving it literally a hair clear.

[LibertyMachine]

Your WCS, how you tell the machine (not Fusion) where the part is located. Is there any additional value in the Z column?

Is your stock sitting flat?

Did your tool pull out? If you go back and touch it off again, is it the same value?

[charlieuk]

are ok yes it zeros back to the same position each time all ok. I machined the bed so that should be level and it has done this a number of times when I have been doing test cuts of the same part and it has done this before, I'm sure the tool has not moved. the first time I had this problem was when I didn't have the outer channel programed in and it then did it on the inner part. since then I have change the machining procedure and now it has appeared on the outer bit.  the part was extra well screwed down this time so think I can rule that out. I'm pretty sure its some setting I have wrong in the cam but will happily be told differently and try anything.

[ivan.stanojevic]

Did you use "avoid surfaces" setting to avoid your tool to touch the top faces?

Edit: I see that you have used this setting for Scallop1 operation but you've not used it for Scallop2.

Why didn't you rough out the small channel before using scallop as a finishing strategy?

[charlieuk]

not sure I will cheque to see if I did, the first scallop file was done by some one else who was helping out  so may have missed some things.

I guess I thought the channel was to small to worry about roughing out, I'm assuming by what you say that I should have roughed it out first as well. 

[LibertyMachine]

Avoid Surfaces is not checked, and the Simulation is not good good. Yes, the tool goes to the top of the part, but it should do nothing more than a faint line, assuming everything is set properly.

The depth of that shallow channel should be 4mm. Can you confirm this?

EDIT:

I think I may have found the issue. Simulation is off, due to some stock definitions. More to come...

This intrigues me.

The original simulation reflects what the OP was obtaining, but it should not have been like that, based on his setup and and stock definition. Changing a couple things changes the result dramatically. 

I realize this is somewhat outside of the scope of your original question, I just wanted to mention the discrepancy.

Backplotting the toolpath didn't yield any discernable difference, which is odd

[charlieuk]

I just adjusted a few things and did the avoid surface for that function and added the channel to the roughing path. yes the small channel should be 4mm radius and 4mm deep.

[LibertyMachine]

And is it 4mm deep in actuality?

[charlieuk]

I will measure it tomorrow I didn't cheque before I left this eve.many thanks

[charlieuk]

so I measured it and the ends seam to have cut .5mm lower than it should were as in the middle it is spot on 4mm, not sure yet if this is in the cutting or in the machine at the moment.

[charlieuk]

ok quite possibly found part of the problem in the material being not quite uniform thickness and also the bed needed re levelling as for some reason it was out. Then tonight we ran into allsorts of problems due to the way the crap china cnc was made with. (This is just a machine i am borrowing) I will re cut tomorrow and see if it solves the problem.

While we are here the adaptive clearing I have set up to do the roughing out doesn't seam to be all that efficient in that a lot of the material is removed doing very short width way passes and not running down the length. Is there any way to change that sort of thing?

[LibertyMachine]

I don't have much time at the moment (in the middle of a setup), but considering you are doing wood (MDF), I'd just duplicate your scallop toolpath (CTRL+D) and have the first one leave stock on and increase the stepover. That will be your roughing pass

[charlieuk]

many thanks no worries I just had a play with pocket clearing and that seams to run length ways instead so maybe that's the one. guess its just a big learning process as to what works well for what.

[charlieuk]

so I have continued to play around with this to try and learn the cam side of things and have managed to get it a bit better. I have changed to 3d pocket clearing to get the roughing out passes running down the length to speed things up however one problem I do have is that when it starts roughing out the first pass of the first and second layer the router raps its self down but then does a full depth and at the full width of the cutter down the centre which its doesn't sound to happy about doing before then going in to its 3mm step over. Is there any way to change this?

[LibertyMachine]

Are you certain that is what it's doing? Running through the Simulation and watching the Z numbers, it takes it's first trip around the part at -1mm deep. You can definitely change this by changing your Max Roughing Stepdown to the value that you would prefer

[ivan.stanojevic]

You might want to try with a different ramping settings, maybe zig-zag?

edit: My apologies Seth, you were quicker.

[charlieuk]

sorry it may have just been on the second layer of roughing and not on the first but yes we cut it in real life and was a bit of a push for it on that initial pass.