Ebay 3040 issue with mach3 - incorrect scale when machining?

[Wayne Kinney]

Hi Guys, first post here

I recently bought an Ebay 3040 CNC mill, Mach3 and Vcarve Pro for an upcoming project (producing model railway track bases).

I've done setting up mach3 with the recommended mach3 settings of the manufacture here:
http://www.jinlantrade.com/ebay/3020t/CNCusermanual.doc

My problem is that when mach3 says the axis has moved say 20mm, it has actually moved more like 30-35mm.

Does anyone know why this might be?

The recommending settings for both x & y axis are 400 'steps per' in mach3 motor tuning, but I could only get it working correctly if I lowered this to around the 320 mark.

Also, it recommends velocity as 2000 for x & y, when I enter this and click 'save axis settings', it changes to 1999.98 or something.

I work in MM's in all cad and have mach3 set to MM's.

If anyone has any ideas, I would appreciate the help.

Thanks,
Wayne.

[riche543]

Wayne

In Mach3 , think its on settings tab , there is a auto calibration for axis, you input how far you want it too move then it asks you how far it did move & it will then set steps per ...... For you, haven't done this for a while just trying to recall off the top of my head but it's there in Mach3. I've used a caliper in the past to measure travel distance, hope this helps
Cheers
Riche


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[Wayne Kinney]

Thanks, I'll give it a go, didn't know about that.

I wonder why the recommended settings would be so off?

[g4ugm]

I was considering one of these. Is it working now?

[riche543]

Yep let us know how you went wayne


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[Wayne Kinney]

Hi Guys,

I did the process for one axis which seems to work. I then broke my milling bit because I am a numpty..

Anywho, here is a video showing the machine in operation, milling a model railway turnout/sleeper base:

[Bob La Londe]

Nice video. Loved the fast forward. I just did a quick look on ebay for 3040, and you have a lot nicer spindle than is shown on the first listing I looked at.

[Wayne Kinney]

Hi,

This is the one I bought:
eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices

Yeah, the spindle or the mount is different in the picture.

[jakuba]

Hello !

This is my first post here ...
I just bought a 3040Z cnc from ebay and I have the same issue with it. The steps per .. parameter in the "manual" is 400 steps / mm but I had to set about 320 steps/mm to get a 1:1 scale... Could You tell what settings are you using now ? It is interesting becuse the ball screw has a 5mm pitch, the steppers are typicall 1,8deg which gives 200 steps per rotation ...


Well I sorted out some problems with my CNC 3040Z. Firstly the scaling issue:
My CNC has got ball screws 1605 with 5mm pitch (before this CNC had trapezoidal screws xx04) steppers are 1,8deg and the controller boards (TBA...) are set for 1/8 which gives:

1,8deg steppers -> 200 steps per rotation AND screws give 5mm per rotation -> 200 steps - 5mm -> 40 steps - 1mm BUT controllers are 1/8 -> 40 * 8 = 320 steps per mm .

Moreover I had strange problems with my computer. After turning on the water pump there were numerous keyboard and mouse hangs sometimes everything worked fine sometimes not. I hooked up the pump to my lab power supply and one of my oscilloscopes. It turned out that this pump injects a lot of noise peak to peak was even 12V !. After opening it I found that there was no filtering at all which is a must in brushed motors. So I soldered a classic two choke and three capacitor filter on the motor and it worked - noise came down to 0,4Vpp.

I thought that my noise problems are over - it turned out to be different after I turned on the spindle. Computer went to sleep ... This time the cure was simple - grounding the whole machine did the job.

After all these noise issues I will change the original cables to shielded this week.

[kronick]

Hi Wayne,
Are you using the stock stepper controller? My attention was drawn to the scale issue when I moved to a Gecko G540 (which I did the first day I had the machine)-- it seems to get the scale correct with the exact same settings as recommended in the setup manual. The stock electronics are crap and might be the problem...

Sam

[mockendon]

Hi all, hoped that this might save someone a couple of hours / few grey hairs.

I bought an ebay CNC 3040 (stock YooCNC controller), arrived quickly, all good, bit of heartache getting it to play with a old pc (had to update BIOS) but then had lots of lost steps which where not consistent (Mach3 calibration usually wanted to make between 415 and 430 steps per), no loose connections (others have had), running smoothish. I tried a 3rd party (sweex) pci parallel card - same as onboard LPT. Turned out increasing the step pulse (motor tuning Mach3) to 15us (recommended 10us in the manual) fixed it completely. It now does 400 steps per and no lost steps also runs super smooth.

[BAMCNC.COM]

I recommend clicking the sherline 1/2 mode on, in general config, also turn your 15 back down to 5. Have you cut any aluminum with the 3040 yet?