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Old Jan 21, 2013, 07:17 AM
EDF rules... :)
AirX's Avatar
Joined Nov 1999
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IIRC DFF wants to cut into the blank from the top not the side. There is a 3D cutting preview in the program and it should show you how it goes about cutting.

Eric B.
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Old Jan 21, 2013, 07:42 AM
The wheels touch down FIRST??
BJ64's Avatar
Australia, VIC, Melbourne
Joined Jun 2009
25,373 Posts
...played with the rig a bit more tonight, and nup... can't get it to make sense.

DevFus Foam shows everything the correct way around, even during the simulation run i.e. the wire comes up to the 'safe height above'... moves across the foam to the origin of the cut, then down into the foam and completes the cut.

When I generate and run the G-Code on the cutter, the &$#!! wire goes up above the foam, and does the cutting path in fresh air above the block

I've tried reversing the Y & B axes, but then it goes all weird on the Y axis.

Do I have to set up the Homing/Limits in Mach3 or something?

BJ
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Old Jan 21, 2013, 07:51 AM
The wheels touch down FIRST??
BJ64's Avatar
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Joined Jun 2009
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Quote:
Originally Posted by AirX View Post
IIRC DFF wants to cut into the blank from the top not the side. There is a 3D cutting preview in the program and it should show you how it goes about cutting.

Eric B.
That part all makes sense, Eric. And it looks correct in the DFF simulation.

I have my rig set up with the X & Y axes on the left, and the A & B axes on the right.

When I use the Mach3 Foam Cutting screenset, X and A move away from me when I push the 'Fwd' jog buttons and towards me with the 'Bk' buttons. Y and B move up with the 'Up' buttons, and down with the 'Dn' buttons.

That all looks to be working correctly.

So then I plonk my test piece of foam on the table, move the wire until it's over the block and just above it - then reset the X/Y and A/B axes so they are all reading 0.0.

Then I load the G-Code and start the run. For some reason, it raises the Y axis quite high while leaving the B axis where it is, then comes over the block and proceeds to try to do the cut - up above the foam instead of down into it.

What am I doing wrong?

BJ

PS - added a couple of pics to refresh the memory. It's a simple tapered conical shape 100mm long...
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Old Jan 21, 2013, 09:09 AM
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Joined Jul 2006
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Have you not hit the mach3 reload g code button?..maybe you've not shifted the axes properly..read the Mach3 manual on the offset axes feature if in doubt
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Old Jan 21, 2013, 11:04 AM
EDF rules... :)
AirX's Avatar
Joined Nov 1999
13,648 Posts
From past experience GMFC drove the wire Frome a set home position. The cnc routers do the same thing, they start at a set home position. So DFF is starting from a set position and driving itup over the block and down to cut then returning home.

Eric B.
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Old Jan 21, 2013, 07:40 PM
The wheels touch down FIRST??
BJ64's Avatar
Australia, VIC, Melbourne
Joined Jun 2009
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Yah - I'm starting to think I haven't set/calibrated something properly in Mach3 yet.

As mentioned, everything looks fine in the 3D simulation in DFF. - wire jumps up to 'safe height', traverses the block, descends down into it, performs the cut, and returns back to the start position via the safe height.

So it must be something I haven't done correctly in Mach3. I watched a vid on YouTube last night which tried to explained the different 'co-ordinate systems' used in Mach3. It was a little confusing, but I kinda got the gist.

I get the feeling that I first have to tell Mach3 what my rig looks like i.e. limits, home etc. so that it knows where the "start" and "end" of a cut are...

More reading and fiddling required LoL

BJ
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Old Jan 21, 2013, 08:11 PM
EDF rules... :)
AirX's Avatar
Joined Nov 1999
13,648 Posts
BJ,

GMFC was ignorant of where it started as long as you started and stopped from the same place. I had to move the wire to the correct position to start a cut, If I had moved the carriages down a bit the program was oblivious to that fact.
What you probably need to do is set your wire at a place where if you skipped enough steps to lose an inch you wont crash on the hard table ie wood base.and far enough back so the carriages wont crash on an end.
When I set the table up for GMFC the software had to be aware of the table size so it would at least keep the machine from causing a crash and breaking things. I have not read thru Mach 3 enough to know where that kind of table setup is located but I am sure it is there.

Eric B.

Just found this, have not read thru it completely but at least it is on topic for your problem.
http://www.machsupport.com/forum/ind...c=10508.0;wap2

I just got finished reading the pages connected with the link above and it should answer your questions in the last post.
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Last edited by AirX; Jan 21, 2013 at 08:28 PM. Reason: Add link, added last sentence.
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Old Jan 21, 2013, 09:42 PM
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South - Africa
Joined Nov 2007
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I am no expert on cnc machine but I have build 2 foamcutters a router and am now bussy with a plasma cutter. Well it has been more thanm a year now since I've used my foam cutter so I'm rusty with all the details but here's a few point I remember and do on first startup off any machine.

1) The machine does what you tell it to - don't tel it to go to a limit stop if there is none, it will run off the table.

Set up your table and mach or emc and make notes ( lots of it) and its some times easier to start afresh than to fix.
Now setup your CAM according to your notes
Now double check - if front is front in cad and machine and left is left, note that my mind in the beginning told me that the wire have to go forward, not come to the front.

Now testing, I usually do something like a 4 inch square (my cutter is 6 x 6 feet) and i do this drawing and CAM work in a normal position and at a slow cutting speed.
Then I move the cutter(wire) to a common center on the machine, mid X and mid Y and start the cut.

If the machine is set up properly and you get things like wire rise before a cut it usually means a setting in CAM is activated or not and it should be.

But this gives sequence give me a way of using a known shat that I can estimate with the eye and show me exactly where to start faultfinding without wasting a lot of foam.
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Old Jan 22, 2013, 04:02 PM
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dpot's Avatar
France, Auvergne, Lapalisse
Joined Dec 2005
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setup your Y B 0.00 on the bed of your machen then it should cut from there.


Quote:
Originally Posted by BJ64 View Post
Thanks DSpot - that's exactly the same screen set I'm using

I think I still haven't set something up correctly - and it's probably in DevFus Foam rather than Mach3. I've played around with the offsets etc. in DFF, but it still doesn't behave like I want it to.

I set everything up, bring the wire down until it's just above the foam block, and when I start the run, the wire goes up and a away from the foam instead of down into it.

I suspect it's something simple again - but no matter what I've tried so far, the darn hotwire wants to cut the pattern in fresh air above the foam instead of down into it. It's almost if up is down and down is up - but everything goes the right way when I use the jog arrows on the Mach3 screen.

C'est non tres amusant...

BJ
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Old Jan 22, 2013, 10:21 PM
The wheels touch down FIRST??
BJ64's Avatar
Australia, VIC, Melbourne
Joined Jun 2009
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I've been trying to figure out how to set 0.0 for my axes in Mach3, but still haven't worked it out yet.

Can you help, DSpot?

BJ
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Old Jan 22, 2013, 11:04 PM
EDF rules... :)
AirX's Avatar
Joined Nov 1999
13,648 Posts
BJ,

I set mine by moving both the towers to a spot that gave a few inches of movable table area. Made sure the wire was at its lowest and made a mark on the table that I could reset the towers to, this was home or 0,0. The verticle axis is set to the lowest point and this is its 0,0.
Then I ran the program. I am sure that DFF will write into the Gcode the path to the part. Hit start and watch it work. With GMFC you needed to set home high enough so that the vertical axis wont crash into a stop at the lowest point. I hope this makes sence.

Eric B.
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Old Jan 23, 2013, 01:30 AM
The wheels touch down FIRST??
BJ64's Avatar
Australia, VIC, Melbourne
Joined Jun 2009
25,373 Posts
I think I may have sussed something out - and it may not have anything to do with zeroing the machine.

Here are the top few lines of G-Code that DevFus Foam generated:

; Begin Header section
G21
G17
G90
; End Header section
F600.0000
; Switch On Hot wire
M3
; Go Home
G0X0.0000Y0.0000A0.0000B0.0000
; Start Cutting Blocks
G0X0.0000Y0.0000A0.0000B0.0000
G0X0.0000Y63.0000A0.0000B63.0000
G0X23.0081Y63.0000A23.0081B63.0000
G0X23.0081Y53.0000A23.0081B53.0000
G1X23.0081Y39.9677A23.0081B39.4531F600.0000
G1X22.8582Y39.9671A22.5724B39.4547
G1X22.7083Y39.9668A22.1368B39.4558
G1X22.5584Y39.9656A21.7011B39.4588

From this, I can see that the first movement away from 0/0 0/0 is 63mm on both the Y and B axes - and thats what it looks like when the machine moves too. 63mm UP from where the wire is set.

That makes is sound like DFF starts the cut from the bottom of block of foam - not the top. i.e. I have to set the cutter up so that the hotwire sits at the bottom of my block of foam before I commence the cut.

I would have thought that you would take the Y and B axes higher than the foam you want to cut, plonk your block of foam on the cutting table, bring the wire down to touch the foam, and commence the cutting program (where it would immediately raise the wire to the amount you've told DFF to use for the 'safe height above the block', traverse to the entry point, and commence the cut from there).

Now that I think I have figured out how DFF and Mach3 work together, I'll try setting things up with the assumption that the wire will start its travel from the bottom of the Y & B axes, and move away from me on the X & A axes...

BJ
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Old Jan 23, 2013, 12:30 PM
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France, Auvergne, Lapalisse
Joined Dec 2005
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in mach screen set just jog to were you wont 0.0.0 xyab and click on X Hors zero the same for Y A B then ever thing will start from there

Quote:
Originally Posted by BJ64 View Post
I've been trying to figure out how to set 0.0 for my axes in Mach3, but still haven't worked it out yet.

Can you help, DSpot?

BJ
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Old Jan 28, 2013, 04:29 AM
The wheels touch down FIRST??
BJ64's Avatar
Australia, VIC, Melbourne
Joined Jun 2009
25,373 Posts
Is there any way I can tell the cutter/Mach3 where the limits are without using dedicated switches?

i.e. can I somehow calibrate the 'soft limits' so that it sets boundaries in software that it can find independent of hard switch points?

I've set my 'travels' up so that they match the distances of the axes, but when I say 'go home' after a reset of x/y & a/b, it moves away from those reset points and seems to go searching for a different 'home'.

I read somewhere that you're supposed to be able to define 'machine home' somwhere - unrelated to current axes offsets... (??)

BJ
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Old Jan 29, 2013, 08:54 PM
Sao Paulo - SP - Brasil
Joined Dec 1996
31 Posts
Hi BJ

It seems your MACH3 is not correctly setup. Try to follow the steps bellow (for Nema23 motors)

1) set MACH3 Units to mm
2) goto Motor Tunning
3) setup each axis (X, Y, Z,A) to the following initial parameters STEP=2000, SPEED=140 , ACCELARATION=80
4) Save each axis after setup
5) Manually, using HotKey (dont forget to configure that...I use arrow keys for X and Y and W S for Z axis and E D fo A axis) place X axis close to start point (it really does not mather)
6) Get a ruler , put it over the X axis and somehow, attach a bended wire pointing to the ruler zero..so that when the X axis moves, the bended wire will point the movement on the ruler
7) go to Settings Screen and right above the RESET, the is a button called Set Steps per unit
8) click and select X axis
9) enter (you have to click the field) the value in mm that you want X axis to move (ie 200mm)
10) if everything is with your machine, X axis will start moving
11) Probably, it will stop near 200mm (measured with the bended wire on the ruller)
12) read the ruler and inform Mach3 how much X axis has moved (ie 191 mm)
13) Mach3 will AUTO ADJUST Steps per and you are done...save the setting.

Repeat for Y,Z and A axis

My CNC, works only with Velocity values under 130...thats because my motors are old. Setup another CNC yesterday and it works well with 200 ....

If, for some reason, the setup does not work, go back to motor tunning and reduce Velocity (100 should be a good starting point)

Hope it helps !

Roger

My CNC...note the bended wire..
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