How can I set the machines tool start position

[oly]

Currently when I create a job the tool is always in the centre, is there a way I can position it, I am aware of tool start position but this does not change the start position its more the cutting start.

So currently the tool starts in the center then moves to one corner where it starts the cut the tool is already at that corner so it moves to the center and back again.

The main reason how ever is for positioning my stock I tend to waste less if I start in the corner else I have to try and calculate where the stock needs to be positioned so that I don't waste much this risks me getting it wrong and hitting the limit of the machines cutting area.

Hope I have explained that clearly, also there does not seem to be any machine specific settings am I missing these or do they not exist.

[sliptonic]

There are two related but different things going on here. One is the rendering of the first segment on the screen, the second is the start point for an operation.

With gcode, a move is always relative to the previous position. Since the first move in a job is relative to wherever the cutter is currently positioned and Path doesn't know that, it uses the part placement in order to render the first red rapids. This does NOT mean the cutter will first go to that position and then go to the actual start point. If it really bothers you, you can set the render start index to 4 in the view properties.

If you want to specify the location where the first feed move should begin, you can set the start point property (data tab) to any vector you wish. There's a related property to either use the set start point or not. This needs to be set true.

Unfortunately there's no GUI tool to pick the start point, so you have to enter the coordinates manually on the data tab.

[oly]

Thanks for the explanation sliptronoic I was going to try that out but instead I am back more confused than ever.

Not sure if This is a bug but in my generated gcode all Z moves seem to be upwards there are no negatives, files attached.

So basically I have positioned my cutter on the stock ready to cut downwards, it first move is upwards away from the stock then it follows the path but moving further and further away from the stock which seems very wierd.

I can get around the initial tool position issue by deleting the gcode so it does not move up initially, but it seems all the other codes are wrong as well ?

Am i still not getting this or is there something else going on ?

gnome-shell-screenshot-5Y3LMZ.png (120.78 KiB) Viewed 4338 times

[herbk]

Hi oly,

if you take a look at the g-code, you can see at line 37 that there is a Z move from 0.0000 to Z 5.0000, - the tool moves up.

But in your .fcstd file i see somethings i don't understand:

The Settings for the heights, "Save Height" and " Cleareve Height" is set to "StartDepth" only. By defautl it should be set to "StartDepth + SetupSheet.SafeHeightOffset".

Did you change that by yourself?

If you set Save- and Clearence Height to Startdepht, your tool dosn't move heighter as the height of your workpeace is. This contends some risk, if your workpeace is o bit heighter as it should be, the tool runs with "G0 speed" into the material.

[oly]

Yes I changed it the tool is already above the stock and I don't really need the clearance.

Basically the tool is above the stock the movement should be from its position to the first hole cut down then move upp and move to the next position.

I could add back in the clearance if you think it would help ?

Also I am not seeing that negative, and if I search for Z- I dont find anything in the file, this line seems to be on line 37 it has negative X and Y but not Z

Code: Select all

37 G0 X-59.9236 Y-76.5036 Z5.0000

[oly]

Its twigged I believe its using absolute positions not relative perhaps and looking at the gcode that's the case this makes more sense.

So I have moved the tool head and set its zero above the wood, so then freecad is moving up to 5mm above the wood because it does not know that the zero position is actuaully 5mm above the wood.

I tend to do this because I attach the stock before I turn on the machine and then position it is there a way I can work around this ?

I am wondering about issuing this command to work around this issue.

Code: Select all

G92 X0 Y0 Z5

[oly]

Well issuing that gcode seems to have fixed things for me anyway I can make freecad do that so I don't have to manually ?

[chrisb]

Well issuing that gcode seems to have fixed things for me anyway I can make freecad do that so I don't have to manually ?

I see three possibilities:

• You can add this to your header. Depending on the postprocessor this can be done with a commandline argument
• You can add a custom command whith arbitrary gcode
• You can move either the base object before creating the job or the clone in the job after creating it.

[oly]

Thanks chrisb for the suggestions think I will stick to typing them manually as any of those options I need to remember todo that.

Be nice if you could configure your machine in preferences and then move the tool head in relation to that in the gui, maybe in the future

[chrisb]

Thanks chrisb for the suggestions think I will stick to typing them manually as any of those options I need to remember todo that.

Be nice if you could configure your machine in preferences and then move the tool head in relation to that in the gui, maybe in the future

Instead you can configure it by modifying the postprocessor. If a commandline argument can be used, you could use an appropriate job template.