Configuration setting for a Practical cnc table

[Patrick Waite]

Let me just start off with Hello Every one. Ok. The problem. One day my table had a mind of it own and the x motor went left really fast and broke of the table hitting the floor. I have senses fixed that. I had to buy a new encoder From APE. My circle are not circles they are egg shaped this problem has been going on for awile. I have been though this table more then once. Ive had the motors sent out to be checked I had a new computer built. I dont no what the problem is. Im thinking the setting for the wincnc are wroug. When I cut a circle the start point is ok. But when its done cutting the circle it always a egg shape 1/8 inch down from the start point. What give. I have been in contacked with APE Automated Precision Equipment to check my configuration setting . But had no luck with them getting back with me. Need some help Please.

Ive been reading about other problem on this Plasma Cut Quality Forum and My table is level. I have even 0 out my machine by entering G28. I entered X10 which the x moves 10 inches from 0 and its 10 inches. I have even entered Y10 which the Y will move 10 inches and its also 10 inches.

[muzza]

G'day Patrick,
Have you done this 10 inch check in both directions, ie -10 as well as +10 as the drive fear may be slipping on the motor shaft in one direction only.
It could also be losing steps if the motor is running at or near it's limits, assuming it's running stepper motors, sorry not familiar with APE.
Murray

[Patrick Waite]

Im Running servo motors. I have noticed one thing as I been doing the check with the X and Y. When I 0 out the machine. I mesured from the end on the Y axis and it 2 7/8 from end to the bridge and I also do the same to the X axis which is 1 5/8 from end to the bridge. I then enter y 10 which the bridge will move 10 inches and when I mesure it it should be 12 7/8 because you have to add the 2 7/8 from the start. But I type in y20 or even y30 I have noticed im losing about an 1/8 inchon both sides of the gantry from the end of the table. I will try to post some picture of what is happing

pic 1

pic 1

[muzza]

If it is consistently losing the same amount each time it is most likely a calibration issue. If it's not exactly the same each time it's generally a slippage issue.
If it is losing 1/8" in a direction regardless of amount ie 10", 20" or 30" it would indicate slippage as the loss is only once in that movement, if it loses 1/8" for every 10" it a calibration issue, not sure what you are running but if it is Mach it an easy adjustment in motor tuning to sort out callibration. If it's slippage remove the drive gears, check that the lock screws are aligned to the flats or divots on the motor and loctite the screws in, when you think you have the screws tight give them a tweak again. If it's belt reduction check your belts too, look for worn or rounded teeth as well as stretch.
Murray

[Patrick Waite]

My system is wincnc sero motors. I use both bobcad cam and Corel draw X3 software. Like I was saying with the y10 its fine. Its when i get out to the other end of the table is when im losing the 1/8 inch on both sides of the gantry. I guess its time to upgrade my table. Not getting any help from APE. But thanks for your help. Time to spend more money to keep my hobbie alive.

[Patrick Waite]

Look at the start point you can't miss it. It started just where I want it to and look what happened it stoped 3/16th from the start point. That is enough to piss someone right off.

[Patrick Waite]

Im not sure this is slippage. Nothing in this picture is even centered. Been dealing with this problem for awhile now. Im getting ready to call it quits