Text Size

Odd Z axis movements

Odd Z axis movements

Postby muttstang » Wed Oct 28, 2015 7:32 pm

So I have my machine together and running and have cut some things with it but have run into some issues with the Z-axis

I was cutting a test piece with a 3d profile surface generated in cambam when the cutter plunged around 1/2" into the material and cut some big gouges across it. I heard the change in pitch from in the house and went out to hit the e-stop. It was cutting fine up to that point and then just made the plunge...

After that I lowered my accelerations and tried again and it finished the part fine. I figured that it skipped a bunch of steps on a retract move.

So I flipped the part over to machine the back and about 1/4 way through the finish cut I go out there and find it air cutting about an inch above the piece. Again, it looked fine up to the point where it stopped cutting. It appears that it did it in 1 move instead of slowly over a series of passes. I've had it do this a few times in the past and then lowered my accelerations to fix it.

I think my current was a bit low on the drive so I bumped that up some and I'll have to try some more. I think I'll get a new lead screw as well as I have a 1/2-10 single start on there so I have to spin it a bit fast, though at 50 ipm it is still within the motor's powerband. I'll be swapping in some 12mm bearing rails that I picked up as well so I'll check to see if there is any binding in the screw as it sits now.

any other ideas on what might be causing this?
muttstang
 
Posts: 97
Joined: Sun Jan 20, 2013 3:55 am
CNC Machine: None

Re: Odd Z axis movements

Postby kevinl » Wed Oct 28, 2015 9:41 pm

there's another setting the controls of Mach3 for timing of the step & direction pulses, you may want to try lengthen them.. I think the setting is from 0 - 3 microseconds.. personally, 50ipm to me is on the top end of a 10 TPI, if your adding any microsteps.
kevinl
 
Posts: 886
Joined: Tue Feb 02, 2010 3:47 pm
Location: Birmingham, AL, USA
CNC Machine: Custom

Re: Odd Z axis movements

Postby muttstang » Thu Oct 29, 2015 3:59 am

they are 5 phase motors that I'm half stepping for 1000 steps per rev.

And I actually have the pulse timing up around 5 or more as that's what the manual for the drivers recommended.
muttstang
 
Posts: 97
Joined: Sun Jan 20, 2013 3:55 am
CNC Machine: None

Re: Odd Z axis movements

Postby muttstang » Tue Nov 03, 2015 2:10 pm

I am swapping in some IKO rails for the Z axis and am going to put a 5 start screw in there. The old screw and lead nut had some binding issues that was probably the culprit.
muttstang
 
Posts: 97
Joined: Sun Jan 20, 2013 3:55 am
CNC Machine: None

Re: Odd Z axis movements

Postby muttstang » Mon Nov 16, 2015 2:53 pm

got a 5 start with a delrin nut in there now along with some nice IKO bearings. It jogs nicely, going to have to try and run a part tonight to see how it does :)
muttstang
 
Posts: 97
Joined: Sun Jan 20, 2013 3:55 am
CNC Machine: None


Return to DIY

Who is online

Users browsing this forum: No registered users and 3 guests

Who is online

In total there are 3 users online :: 0 registered, 0 hidden and 3 guests (based on users active over the past 5 minutes)
Most users ever online was 158 on Thu Mar 08, 2012 8:54 pm

Users browsing this forum: No registered users and 3 guests