DM542A, Nema23, DB25-1205, Longsmotor

Hello @ all,

I'm new in this forum and have build my first cnc wood (mdf) router - and it's working

I'm 42 years old, working in a mechanical engineering company and living in Germany. My last english lessons at school are a lot of years ago, so sorry for my mistakes and simple english

The last weeks I read a lot of threads and posts in this forum and found a lot of answers from the experience of other users. I don't understand all but I worked like "try and error"

1.) My cnc router ist not working like I want. Today I milled a rabbet 720 mm long, but the rabbet is only 717 mm long, so the machine lost 3 mm. Maybe this is a mistake in my setup.
2.) The stepper motors are hot after a few minutes. I can touch them only quickly, so i think they have around 140°F / 60°C.

hardware and settings:

DM542A from longsmotor
SW 1-3 OFF (3.00 A/RMS; 4.20 A/Peak)
SW 4 OFF
SW 5 ON; SW 6 OFF; SW 6 ON; SW 7 ON (800 Pulse/rev Table)

DB25-1205 BreakoutBoard (BoB)

Nema 23 Longs Stepper Motor 23HS9430 (1.8 deg/step)

I have 2 setups at stepconf, 1 I called Leadshine, the other WanTai - following the settings:

Base Information:

Machine Name:	Leadshine	WanTai
Axis configuration:	XYZ
Reset Default machine units:	MM
Step Time:	2500 ns	5000 ns
Step Space:	2500 ns	5000 ns
Direction Hold:	10000 ns	2500 ns
Direction Setup:	10000 ns	2500 ns
One Parport
Base Period Maximum Jitter:	30.000 ns

Axis X:

Motor steps per revolution:	200.0
Driver Microstepping:	4.0
Pulley teeth (Motor:Leadscrew):	1.0 : 1.0
Leadscrew Pitch:	4.0 mm / turn / Umdrehung
Maximum Velocity:	20.0 mm / s (1200 mm / min.)
Maximum Acceleration:	100.0 mm / s
Home location:	0.0
Table travel:	-1.0 to 720.0
Home Switch location:	-6.5
Home Search velocitiy:	1.5
Home Latch direction:	Opposite

Some words are in german, sorry for that, but I think you'll know what there ist standing

Thank you very much for your help and I hope this is only a problem of settings.

greetings Thomas

I milled a rabbet 720 mm long, but the rabbet is only 717 mm long, so the machine lost 3 mm. Maybe this is a mistake in my setup.

Have you tried making the same move without the bit touching the work "air cut" to see if it moves the correct distance when not under load?

Rick G

Hi Rick,

thank you for your help. I tested it now with "air cut", the machine moves exact the way. Perhaps I did a mistake in the .ngc file, I wrote the gcode by myself.
The distance between 2 points is always the center of the bit, right? Maybe i forgot to add the bit diameter or I made a mistake between work zero and machine zero.

Anyway, I started a new project today, my machine is to loud and I live in a apartment. I build today a box around the machine and next projekt is the exaust because I cant use the vacuum cleaner in the box

greetings Thomas

The distance between 2 points is always the center of the bit, right?

May be not, if you are using too offsets.
linuxcnc.org/docs/2.6/html/gcode/tool_compensation.html
If you make the same move with both a "air cut" and a regular cut and there is a difference that may indicate missed steps flexing, etc.
A good test is to home the machine, make some cuts and then command a return to home position and using a indicator see if the machine returns to the correct location.
If you are going to use a shop vac and are concerned about noise look at the noise specs. we use a Fein and it is much quieter than others we have used.

Rick G

I'll read the tool compensation the next days and also I'll do different tests with the machine.
I've to finish the box first
Kress company documentation says sound pressure level 78 dB(A) and noise power level 89 dB(A). My phone app decibel meter says the same, 77 dB(A) without cutting and box open, 62 dB(A) without cutting and box closed. The most noise is coming from milling, not the milling motor itself, I think. Remember, my box doesn't have insulating materials at the moment, but its a good base to reduce the noise.
Tomorrow I'm at work again and when I've finished the work, I'll take a professional decibel meter with home to measure the noise.

What do you think about the stepconf file? Are the settings ok? What do you prefer, the Leadshine or the WanTai settings?

I do not have any experience with those drivers, but there is documentation for theDM542...
www.americanmotiontech.com/upload/Manuals/DM542m.pdf
On page 3, I would say that is a good starting point.

pulse longer than 2.5μ...
and direction 5μs at least

Rick G.

@Rick G: thank you, I changed the settings of "Step Time / Space" to 5000 ns and "Direction Hold / Setup" to 10000 ns. Also I changed the DIP switches of the DM542A to 1 ON and 2-3 OFF (2.69 A/RMS; 3.76 A/Peak).

@andypugh: thank you too, then I'm reassured.

The weekend is coming, the cnc router works with a acceptable noise and the dust extraction is ready. Time to use the cnc router and work with it

Also look at Dip SW4 which controls "Stand still current setting"
Which allows for automatically reducing the current and as a result the heat while the motor is not moving.

Rick G