Giant 20' x 3' x 2' router build

**charlieuk** · 22-12-2014

I have changed to a 2:1 gear ratio and made sure it is all running smooth however I still seam to be getting the problem. I am just trying the job at 50% feed rate to see if that stops it. We are wondering if it happening when there is a fast change in direction and feed rate because of the heavy z axis. We think it is sways happening during a similar movement but not at the same point in time through out the job. Wondering if possibly we need to put a gas strut on the z or go up further on the gearing at the moment I have a 20t and a 40t

**EddyCurrent** · 22-12-2014

Originally Posted by charlieuk

then second is there a way to hock up a signal to go to e stop if this happens for any other reason. ( I have yet to look into this)

This is how I did it for the similar (I think) AM882; http://www.mycncuk.com/threads/6565-...7622#post57622

Contacts of the K2 relay would go in series with your emergency stop buttons

**charlieuk** · 22-12-2014

just to add to thins the weight of the z axis is aprox 14kg and its on a 1605 screw and a 3nm nema 23. I ran it at 50% and it actually cut out sooner. I have got another set of pulleys coming which will give a 3.8:1 ratio so hoping that may help and in the mean time Im going to try taking of the spindle to reduce the weight and see what that does.

**JAZZCNC** · 22-12-2014

Originally Posted by charlieuk

just to add to thins the weight of the z axis is aprox 14kg and its on a 1605 screw and a 3nm nema 23. I ran it at 50% and it actually cut out sooner. I have got another set of pulleys coming which will give a 3.8:1 ratio so hoping that may help and in the mean time Im going to try taking of the spindle to reduce the weight and see what that does.

Charlie from what you told me regards velocity and Acc settings being so low and with 2:1 ratio then it should handle the weight without stalling or missing steps.
When my machine was vertical the gantry was much heavier than 14Kg and a single 6Nm nema34 which turned twin 5mm pitch screws via belts that where geared 1:2 to give speed so actually lowering torque by aprox half easily moved gantry. This means you actually have more torque than I do.!

If your absolutly sure there's no sticktion on the linear motion side then Things to check First is if the motor is wired correctly and performing properly.? Have you wired it in parallel or series.?

With 3.8:1 ratio you will be quite low on speed and Acc you'll reach which for 3D work you may want.? So I would try to find the cause.
Counter balance/Strut arrangement can't hurt if you have room to fit so I'd do this any way just to help take the the strain.

**charlieuk** · 22-12-2014

I'm prity sure all is sliding ok. The z axis would fall nearly the hole way under its own weight with the belt removed from the stepper and with the spindle removed it was still triggering. I have since got the screw a hair better by shiming it .10. We did adjust the speeds this morning with the gearing but we have backed the acceleration back again and running another test now

**charlieuk** · 22-12-2014

I forgot to say the steppers are in parallel

**charlieuk** · 22-12-2014

Ok so the final test we did this eve was to swap the drivers over for the y and z which are the same and also slowed the acceleration down further to 150 and this managed to run through the hole cut without stoping so tomorrow we will switch the drives back and keep the acceleration the same and see if that is still ok. What we did notice though is that the steppersare getting quite hot (45-50 deg) Im not sure if it is directly linked to the problem as it happened on the first test of the day but it spears that they need to be set to run cooler? Is it because they are set in parallel and not running very fast? Although I have a lot of travel the y and z only travel very small amounts at a time when cutting a board.

**JAZZCNC** · 22-12-2014

That's not hot for steppers so don't worry too much about it. Esp if they are moving slow rather than stood still as they will be using full torque to hold position
and not going into current saving mode.

Are you sure the drives are set correctly regards Amps and motor setting.?
What number or letter is the dial set to on the drives.?
Have you tuned the drives using protune or just using the dip switches.? If not try to use protune and make sure the amps are set correct for the motors. Wrong amps setting would cause this problem and the drives default to a low setting if I remember correctly. If you have the wheel set wrong on the drive it will think it's using differant motors and can default to low amps setting and wrong PID tuning in the drive.
Do the motors make any whistling or loud buzzing sounds.?

150 on acc is far too slow for any z axis and you should be able to go much higher without any trouble. So this must be either your set wrong in the drives or there's binding at some point.!

**charlieuk** · 22-12-2014

Ok that's good to know regarding temp, I will look at the settings tomorrow but we have them just set on the closest setting on the switches at the moment as I didn't really understand the pro tune. I will try and down load it again in to the new computer and see if it makes any more sense now I know a little more. The motors are quiet and don't seam un happy. I will be back with more info in the morning many thanks for the help

**charlieuk** · 23-12-2014

These are the settings I have for the z. I am struggling to load a driver for the USB to 232 cable for windows 8 that I got from zapp. The cd it came with says windows 8 but it's all in Chinese. We have just swapped the drivers back and re running the file to see if the problem comes back