Initial workpeice tooling set-up instructions using a pendant controller type machine

[Nthkentman]

Using an eMach EM900 machine with the pendant controller

Can anyone improve the route below ?

I'm trying to remember how to set-up the work and axis before starting cutting, watched a few U Tube clips and have decided on the route I have written...



In VCarve (Or your program for designing etc) set machining datum to TOP of workpeice for eachmaterial at material CENTRE for X & Y for all work designs
Insert pointer rod into tool collet to use as alignment tool for workpieceedges along X axis, mark workpiece centre using lines across from corners with a pencil.
Align workpiece edge along X axis using pointer and handsetrapid along workpiece edge and move work to align with x Axis before clampingetc
Clamp, stick, or whatever the workpiece to wherever requiredon table/platen
Using handset find drawn centre marker, jog to exactly the centreof the X marked on job eyeing up the cross lines.
Remove pointer after zeroing WORKPIECE axis X & Y todatum centre drawn lines in your pendant or software
Fit required cutting tool for the job into collet ready for Z Axissetting
Using handset set tool to “Touch Off” at job top face. Justkissing the top face
Zero Z axis using pendant or your software. Axis setting is now complete.
Ensure workpiece is fixed ready for use.
Reduce feed rate, start machine after loading required G code/Design and watch for issues, increase rate whensatisfied all is Ok.

[EddyCurrent]

That's fine for jobs that work about a centre line e.g. guitars, but I would think most jobs are referenced to the bottom left corner, the X0,Y0 corner
If you are doing repeat work you might want to think about 'fixtures' using G55 - G59 coordinate systems.

[JAZZCNC]

There's not right or wrong way or better or worse it's all down to preference.

My setup is mostly done from lower left corner but in the case of a circle I may use the centre it all depends on the job and material it's coming out of. Often i'm cutting parts out of existing sheets and with a circle working from centre is easier regards waste and fitting into available space etc.

If your mostly using square sheet material then I'd setup reference bump stops or edges along each axis so can work from same X0 Y0 WORK coordinate and cut this process out. Only needing to set the Z ZERO. (if using same thickness material won't even need to do that.!)
You should be able to set the G54 WORK OFFSET in the control. G54 is often the default OFFSET and will be the last place you set the WORK ZERO if the OFFSET was saved before closing down the control. So you can predefine a spot on the table and save as G54 default which will always be the same unless explicitly changed by you or G-code.
On first startup you should always HOME the machine first before doing anything. Then after this the Control nows the OFFSET's and because G54 is the default then it will be set to the spot on the table you designated ZERO for G54. Which is be the corner of the material when against the bump stops.

Even if you change the G54 OFFSET in g-code while working so long as you don't save the WORK OFFSET when finishing cutting session the machine will start backup at the spot you selected after homing.

One thing I will mention with smaller jobs is not to work on the table in one spot all time but to move the smaller stuff around the table to lower wear on the ballscrews in one area.

[Nthkentman]

Thanks Jazz for the advice.

I set a 19mm sacrificial board on the machine today and on top of that I set a small 200 x 120 x 13mm thick piece of ply

After setting the machine to "HOME, I then, using my procedure above, brought the arm axis's to the centre of my workpeice. Positioned the cutter to the correct marked centre and zero'd X & Y.

Then I brought the head down and jogged until the cutter (A 3mm dia single flute end mill) just touched the surface and zero'd Z

In my V Carve software I set the XY to centre of the work, and the height of the material as 13mm. Reference start for Z axis was top of workpiece at centre.

When I started the machine and set it all in motion the X & Y axis travelled to the exact set point in the middle of my piece as expected, but the Z rapid plunged into that point to the collet nut depth ! (Until I hit the E Stop button)

What did I do wrong? I'm missing something here and feel a little dumb.... Newbie cock up I know... Loooong time since I did this and it's a fun learning curve again

[Clive S]

By default V carve sets the material z position to the bottom of the job. Did you change it to the top?
Also did you have the "model in material" set to "gap above model". .. Clive

[Nthkentman]

By default V carve sets the material z position to the bottom of the job. Did you change it to the top? Clive


Hi Clive, yes I did change it to the top. The diagram shows as you say the default at the bottom of the workpiece, (Which I also tried) but irrespective of how I set it the Z axis is wrong... I'm wondering now if I am sending the wrong G code to the machine.
The PP asks for a file with extension .nc
So I use the first available .nc choice as my machine is not listed.
Perhaps I'm doing that wrong ?

[Clive S]

Well if you want to be sure have a look at the gcode it produced you can open the file by renaming it to .txt ..Clive

[Nthkentman]

Thanks Clive, I may try that and post the results here. I'm fairly new to G code, as when I were t'prentice the programming and such was done by the clever office bods :-)

How would I detect if the code is wrong please?

[Clive S]

If you post the top 20 line of code it should be easy to see. you just look for the g1 z!!! parts. Did you re read my edited post lower down for the position of the model in material. ..Clive

[Nthkentman]

I'll got to my machine tomorrow and get the file. I'm not sure what you mean about the position of the model in the material though. Sorry if this seems a bit dumb, but I did think I could remember more ... Maybe not

[Clive S]

On my version its on the right hand side under Toolpath operations (setup material and rapid gaps) set your Z to the top and Gap above model to zero. ..Clive

[Nthkentman]

Ok, Material setup screen on RHS reads as follows....
Material Z Zero, red spot top left corner. Thickness 13mm.
XY Datum centre spot selected. No Use offset" ticked.
Rapid gaps above material
Z1 45mm (Need to clear a clamp) Clearance
Z2 4.8mm (Plunge)

The preview shows the cut ass I would expect.... about 4mm into the work surface

I'm thnking I've set something wrong here...
Will post the actual file from the machine tomorrow into this thread somewhere... I'll open it in Notepad and see if I can see what's gorn awry too

[Clive S]

Ok you have a different version to me. you could post the .crv3d file if yours is the same then I could check it. But the gcode should also do. ..Clive

[JAZZCNC]

What did I do wrong? I'm missing something here and feel a little dumb.... Newbie cock up I know... Loooong time since I did this and it's a fun learning curve again

Don't feel dumb we have all been here in some form or another.! . . My first attempt with G-code ended thumping a perfect square hole thru 40mm of MDF after sending Z axis wrong way. . .Lol

I don't use V carve but If it's not that you have set the Zero point at bottom of material and you can't find any obvious reason then it could be the Control as a TOOL offset set.
Just like WORK OFFSETs you can have TOOL OFFSET's so your control could have TOOL OFFSET's entered into it.?
So when your G-code calls for first tool it applies the OFFSET set in the control. This could give the trouble your seeing.

If you open the G-code file you look for G43 H# with the number being the tool number probably 1 in this case. It will be some where near the top and probably will be near the tool number IE:
T1
G43 H1

If so then chances are you have TOOL OFFSET applied. Just remove the G43 H1 or put G49 straight after it.

[Boyan Silyavski]

Check this:

13233

The post processor is this inch or mm with or without the ATC/adds tool change command/ and the out put is txt in both cases, not .nc

13234

[Nthkentman]

Hi Clive,
I am actually using version 6 V Carve.
But playing with the Version 7 trial too. I may well just bite the bullet and buy V7 as it's far more explanatory and easier to use.

I'll pop down the lock-up tomorrow and dump the files onto a stick and then have a gander. Will post whatever I find and hope it's me being a plonker and not a duff machine reading the code wrong.
Emach machine...looks like a Chinese version, using a Chinese PP program and spindle head.

We will see.... I've only got a few weeks to get this sorted as my new unit will be ready end Oct, and I *really* need to get cracking on some stock to sell

[Nthkentman]

Thanks Jazz, I actually believe it's me getting it wrong tho... I only have the facility for XY offset in V Carve,
I wonder if plain G Code in txt will work, even though the PP program suggests .nc extension... Not sure why there is a difference....
Looks like I'll be installing Mach3 and getting someone clever in to convert the machine board otherwise

[Nthkentman]

Hi Silyavski,

My PP file extension needs to be .nc according to the instructions. Not sure if it will accept metric .txt, but I may try.
I'm setting the machine toolpath in "Profile Toolpath"...Do you think I should be using the "Pocket toolpath" instead ? The setings in your picture are the same as the ones I my program too,
My intention is to cut 4mm MDF/Ply on a sacrificial backing board to allow the cutouts to be used/pushed out then finished after for sale... Items like hearts, stars, letters and numbers etc

[Boyan Silyavski]

Sorry , i though you use mach3. Though you can just rename the file.

There are places that profile is used, there are places where pocket is better, to avoid triangualr and similar small left overs. Though it could take a bit longer.

[JAZZCNC]

Thanks Jazz, I actually believe it's me getting it wrong tho... I only have the facility for XY offset in V Carve,

It will allow tool offset's I'm sure of it. Not much good if it doesn't as many machines need tool offsets to work correctly, esp with toolchangers.




I wonder if plain G Code in txt will work, even though the PP program suggests .nc extension... Not sure why there is a difference....
Looks like I'll be installing Mach3 and getting someone clever in to convert the machine board otherwise

The file .nc extension will open in notepad. When you click it to open and get the message saying choose software to open with then use notepad and save as default for this file type.

If you create file in note pad then just replace .txt with .nc and it will work. Both are just plain txt files the .nc extension is nothing special it's just the DSP will be looking for .Nc extension. Chances are it will use .txt as well and just defaults to .nc.?

[Nthkentman]

Morning Jazz
I'll go get the actual machine settings and G code file in a short while...
The V Carve program Material Setup window is shown on the BMP pic which might help when I post the one I have from the machine computer with the info I have in it and the code
13235

I'm sure it's me not setting the software correctly.
Fortunately I have tracked down through Linked-In one of the guys that worked at eMach as a technician and he's going to help me over the phone to check out the machine too...

[Clive S]

Mine is different:-

13236
as you can see so the gcode will help. ..Clive

[Nthkentman]

Hi Clive,

Looks like your version is V6, which is what I have on the actual tooling machine PC.


This morning I have made progress, in that after talking to Will Stirling, the man who was install and build tech at eMach I have discovered the G code extension should be G-Code Arcs (mm) .tap

After playing around with axis settings again I have SUCCESSFULLY cut out a letter ! (WOOOT !)

All I neeed to do now is refine the process to give a better finish and fine tune and I *think* I'm up and running... albeit staggering at the mo LOL!

This forum is a goldmine of help, and without you guys I might have been tempted to give up before I start... Now I need to get designing and make some stock

[Clive S]

Glad you got it sorted. Its a big high when you do your first successful cut. :toot:..Clive

[Boyan Silyavski]

Great! I knew it was there the problem. Happy cutting!

[JAZZCNC]

Great stuff and don't be afraid to give stuff ago, if your unsure just set the Z height high at first so it cuts air. Give it Few weeks it will be second nature then in few months you'll be doing stuff that blows your mind.!

Your problem must have been you wasn't loading G-code and running something in memory because the file extension wouldn't change the actual G-code produced by CAM. This is why I don't like these DSP controllers.? You can't easily see what's happening regards the G-code and machine setup.

This would have been obvious on Screen with Mach3 or Linux cnc.
Not saying convert but it's the little things like this that often lead folks to convert.