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Lifting the Spindle at Beginning

6 REPLIES 6
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Message 1 of 7
Formatize
556 Views, 6 Replies

Lifting the Spindle at Beginning

Hi Guys,

 

I'm using fusion 360 Cam to produce Gcode for my CNC that uses GBRL as a post processor. The provided GBRL post processor in fusion works fine but I only have one problem:

 

The job starts with the spindle moving to the starting point, lifting and then plunging to the correct depth. I would like it to first lift the spindle and then move to the starting point. Otherwise it scrapes along the stock and ruins the surface.

 

I've tried searching for a setting in the Cam and also tried to edit the gcode, with very limited knowledge, after producing the file but without result.

 

Can someone please advice me what to do.

 

 

6 REPLIES 6
Message 2 of 7
ivan.stanojevic
in reply to: Formatize

Hi,

 

I'm not sure if I've understood you, but you might want to try turning off the g28 when postprocessing.

Just try and tell us how it goes.

 

eee.png



Ivan Stanojevic


Message 3 of 7

Hi Ivan.

 

6 years waiting for a response must be super frustrating... I will reply!-

 

I have been having the same issue.

The bit moving direct from Zero, across  the surface to the first cut. Undesirable!

I have been manually editing the code to get lift on Z at the start of a job. The next time I'm at my machine, I will try this and let you know.

I imagine it's a problem for a lot of newcomers. Myself included!

Just a thought-

Why is this the default Setting?

I certainly didn't turn it on!!

Kindest regards,

 

Jon T.

Message 4 of 7

@theaudioasylum Is the code something like this G91 G28 Z0? If you have limit switches or set the machine Z datum it will move to the machine's home position not to the zero on the top of the part.

 

Here's some info on G28.

 

Mark

 

 

Mark Hughes
Owner, Hughes Tooling
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EESignature


Message 5 of 7
engineguy
in reply to: theaudioasylum

@theaudioasylum 

 

In the grbl control there is a clearance setting that you can use to set the height above your stock for such moves, consult your grbl manual for how to use this facility, otherwise use the G28 G91 Z0 (The Z Zero is your machine Z Zero, not your stock Z Zero) as previously suggested.

 

It is not a Fusion problem, that is how grbl is designed to operate 🙂 🙂

Message 6 of 7

try this attached post for size. It will also allow you to set your relative home position as well as spindle dwell 

Please click "Accept Solution" if what I wrote solved your issue!
Message 7 of 7
theaudioasylum
in reply to: Formatize

So.. It seems that I am using a different machine to the one being discussed.

But, the same issue is present.

I logged into Fusion for the first time in a while, on a new computer, installed the recently updated Stepcraft Post processor and put together a contour tool path and was gifted with this-

(1001)

(T1 D=6. CR=0. - ZMIN=-16. - flat end mill)

G90

(-Attention- Property Safe Retracts is set to Clearance Height.)

(Ensure the clearance height will clear the part and or fixtures.)

(Raise the Z-axis to a safe height before starting the program.)

 

(2D Contour1)

T1 M6 (flat end mill D=6. 6mm Flat Endmill)

S10000 M3

G64

G90

G54

G43 H1

G0 X28. Y-69.348

Z14.324

G0 Z5.

G1 Z2.5 F666

Y-102.615 Z2.408

 

As you can see, If you start a job immediately after Zeroing on workpiece, the bit will move straight across the surface. Not desirable.

I note the recent addition of this line, at the beginning of the code-

(Raise the Z-axis to a safe height before starting the program.)

 

Which does solve the problem.

 

It should be incorporated into the post.

For such a precise coordinate system, it seems odd to have to "raise Z a bit" rather than post moving Z to Clearance for instance.

 

I normally edit the first two coordinate lines from-

G0 X28. Y-69.348

Z14.324

To 

Z14.324

G0 X28. Y-69.348

Giving you the lift after Zeroing and preventing any issues at program start.

 

Apologies for veering off the subject machine.

I hope my discoveries help someone who has also ruined loads of stock because of the same oversight! 

 

Thanks for contributing everyone!

 

 

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