# Machsupport Forum

## Mach Discussion => General Mach Discussion => Topic started by: Paul4865 on July 23, 2012, 07:06:39 AM

Post by: Paul4865 on July 23, 2012, 07:06:39 AM
Dear all,
Just completed the construction of my 4Th axis. I am looking for best practices for set up in Mach 3, I have built this because I saw a candle stick that was hollow and twisted and wanted to try and make one but I do not have any idea how to set it up. I could do with the infant version on how to set up the steps for a rotative axis and what tick boxes I need to fill in, I am aware that the radius of the work will determine how the axis moves but I do not know what drives this. I use solidworks to create all of the dwg data that I import into a hobby version of Bobcad to post out to the machine, had allot of fun making my own gears and chassis for the axis but now I am stuck and need to lean on your greater knowledge, I have read some posts on 4Th axis and it seems to be a problem for everyone.
any guidance or advice would be appreciated.
Thanks, Paul
Post by: BR549 on July 23, 2012, 09:42:29 AM
The 4th axis sets up in Degrees per minute.

(;-) TP
Post by: Paul4865 on July 30, 2012, 03:44:01 PM
Got it going and set up with a little help from reading the manual, cocked the gearing up completely so it has been rebuilt geared down by factor of three, I have drawn a compass with .5 degree increments and I am using the set steps wizard on the settings screen, the Axis is still not moving consistently, I have run the wiz about 10 times and told it to move 90 degrees, each time it returns a different amount.
what am I doing wrong?

any help out there?
Post by: BR549 on July 30, 2012, 08:59:43 PM
what is the gear ratio? are you micro stepping the driver ?

200 X Micro steps X Gear ratio /360

I would set the micro steps to 6 if possible abd then you have an even division into 360 and a resolution of .1 deg.

200 x 6 = 1200 X3 = 3600  /360 = 10 steps per deg or .1 per step

Just a thought, (;-) TP
Post by: Paul4865 on July 31, 2012, 02:38:00 AM
I have the breakout board dips set at 25%, this gives me 75% power and seems to be the smoothest setting, this drives the micro step to 1/2. I must admit I did not consider the gearing as a factor for accuracy, Thanks for that.
I will cut some new gears to harmonise the gear ratios to my 200 step motors and try again.
Regards Paul.
Post by: BR549 on July 31, 2012, 10:34:07 AM
YOU need to read up on your drives to SEE what options you have for microstepping.

(;-) TP

Post by: Paul4865 on July 31, 2012, 10:42:59 AM
The board has 4 settings via dip switches
100%, Decay Mode Fast, micro stepping 1
75%, Decay Mode 25%, micro stepping 1/2
50%, Decay Mode 50%, micro stepping 1/8
25%, Decay Mode Slow, micro stepping 1/16
the drive will not move on 25%
Post by: BR549 on July 31, 2012, 10:50:39 AM
what make and model board? I have no idea what decay mode is.

(;-) TP
Post by: Paul4865 on July 31, 2012, 10:55:08 AM
No make on it, the only distinguishing feature is the chip Toshiba TB6560AHQ E Bay special probably from the East.
your not alone with decay mode.
Post by: Tweakie.CNC on July 31, 2012, 11:28:48 AM
There is some information on stepper motor decay mode here ;  http://www.stepperworld.com/Tutorials/pgMicrostepping.htm

Tweakie.