x,y and z axis problems on 3040T

Hello all.
I have a Cncest 3040T, using Autocad to DXF, SheetCam for GCode and Mach3 for Machining.
There is a thread on here where kev2960 has a similar problem, but it's not solved.
when cutting a circle within a circle in 9mm MDF, at 1mm plunges, the first pass is perfect, then with each plunge it shaves a bit extra off the south side of the piece and steps the north side of the piece, by approx 0.3mm, giving an eliptical shape when finished, and when returning to the home position, its not where it started, it's north east of its original point by some 6mm or so. The DRO reads 0,000 on all axis.
the settings ive tried in mach3 motor tuning are:
steps per velocity acceleration notes
400 2000 300 all as per set up manual, awful results
410 2000 300 same rusults
405 2000 300 a tiny bit better
405 1500 200 same as before
405 1000 100 awful and really really slow
410 1000 200 same as the rest but landed no where near its home position

any advice or settings much appreciated

Hi there, Yes your quite right it has been a mission to get my machine running as it should, but now i can't fault it. mine is a 6040 but try the settings i've figured out.
Port 1 35000 Hz
Motor Tuning;
X Axis 320 1500 400
Y Axis 320 1500 400
Z Axis 400 1500 400
Set The step Pulse & Dir Pulse both to 5

Motor Outputs
screen shot won't upload at the moment but these are the settings i've got

X En (green Tick) 2 3 dir Low Active
y En 4 5 dir Low Active
Z En 6 7 dir Low Active

(Your pins may be different from mine)

When you start Mach3 change the feed rate from 6 to 100, this will give you 1500 mm/m rapid

Hope this helps
Kev

Much appreciated, Kev.
I'll try those settings when I get back from holiday.
Was it the settings that were causing your issues?
Was it trial and error to get to those figures?

Yeah kind of methodical trial and error, that doesn’t really make sense but by changing one thing at a time I got there took about a month. In a recent post of mine I made some pointers to check that each stepper was returning back to zero. Just put a felt pen mark on the wheel of the stepper and a piece of cardboard as a pointer you’ll probably find the steppers don’t return to zero.

Can you send me a photo of your machine or a link so I know what it looks like?

Awesome idea Key.
This is the exact machine I have Look at this on eBay http://www.ebay.co.uk/itm/282545167242
I bought it from a guy who didn't manage to use it so was brand new.
It seems weird with mine as when the first plunge is cut, it's perfect but the more plunges it does, the further it creeps north East.
I'm going to try your settings for it though and see what it does.
Edit:
I've ordered the Kress 1050 which should be at home when I get back

One slightly odd thing I see in your settings. You appear to have "active low" selected for step and direction on all axes. That's fine for direction - change this and the machine reverses direction on that axis. However, "active low" for the step signal is unusual for the usual breakout boards/stepper drivers. The effect is that everything seems to work fine, but each time the machine changes direction on that axis you lose one step. Enough direction changes and the axis gradually seems to drift in one direction, fairly repeatably. Your test pieces don't seem to have that many direction changes compared with the overall error but as it's such an easy thing to change (and change back if it makes no difference) you might like to try it. I had this problem on the Z axis on my own machine; didn't notice a problem for simple profiling constant-depth cuts but when I started some complex 3D cutting, the cut depth gradually increased.

(Misread post - Kev's post says "dir active low", not "step". But worth checking that step is active high anyway.)

You’ve ordered a Kress 1050 ?
Didn’t your machine have a spindle when you got it

Here are the screen shots of my set-up, i'm not saying they will work for your's but it's worth a go

Photo 1 Motor Outputs
Photo 2 Input Signals (for home and limit switches, I have only home switches)
Photo 3 Output Signals
Photo 4 Encoder/Mpg's (handwheel, if you have one)
Photo 5 Spindle Set-up

The "motor" is a Dremel type of thing and is utterly useless for my needs.

I received my Kress 1050w today and put Kev 's setting into mach3 as he suggested and did an air cut first followed by my first aluminium piece. All is perfect!
I'd like to say a massive thank you to you Kev for helping me. I don't know how or why it's working but it is.
I'm very happy :)

Hi,
I found this on a hunt for answers, my cncest 3040T was ramping rapidly, I checked the settings and z was way off. So I reset all to 400 1500 400.
But Z is still ramping slightly from 0.000 start at stock point, after 180° return to zero it reads 0.0025 but its actually 1.0025mm.
It's the 800w machine with the water cooled spindle motor.

Is it the first block or third block of numbers I need to change in motor tuning to try and keep it level?

If it's a straight radial cut it's fine. But there are rises and dips in the model so it's after repeated direction changes it runs off.

I also have axis problems on my 3040t cnc. The x-axis doesn't move. There is a grinding noise? The knob turns with Mach3 back n' forth and moves x. I'm not familiar with cnc's? Is there some type of Ball Nut on the rod. Is there a plastic nut. Can it strip? If so where can you buy one?
Whatever is hooked to the t-rod to move the motor rt and lft. has a problem! I'm a super newbie to a 3040t. Please help!
Thanks,
Tom Megna

Today seems to be a day of thread revival :)

Tom, help us to help you a little. Photos always help immensely trying to understand a machine from across the pond. The term "3040t" describes a generic form factor of typically Chinese machines without any clear indication of the actual machine build.

You mention a noise, a turning knob? (is this attached to the motor?) - I'm going to assume that the motor has two shafts - one driving the drive screw and the other with a rotary knob affixed. And trying to move the X-Axis the knob rotates?, but the bed does not move? If so you might be right with your thought process, but I'd hazard a guess that there's two devices to investigate:

1) Motor coupler - connects the motor shaft to the lead screw. That is normally fixed by two grub screws, 90 degrees opposed on the lead screw; and a second pair of grub screws tightening the coupler to the motor shaft. If these are loose then the motor won't drive the drive screw.

2) Ball nut. Or trapezoidal nut, or delrin nut, all depends on the machine build. But, yes, a nut assembly that fixes to the bed that traverses the drive screw. If that's stripped (possible with a delrin nut) then it could explain your observation.

You're going to have to get your hands dirty and a screwdriver out to look at the mechanical behaviour of the machine.