Text Size

Missing Steps on the X Axis

Missing Steps on the X Axis

Postby bigred8080 » Mon Dec 05, 2016 4:53 pm

I know replies on here have been scarce lately, but i figured it was worth a shot...

I have been playing with the velocity setting (motor tuning) in Mach and have reached a point where i seem to be missing steps.

My set up is as follows:

NEMA23 425 oz. stepper offered here as a kit.

i am using the BoB, drivers and PS that are included in the kit.

currently using 13 TPI all thread.

Mach set up:

Steps per - 10400

Velocity - 20

Acc. 5

I have checked to see if my coupler is slipping and it is not.

I have read that some people here are getting 30ish IPM out of their book builds. What gives?

I posted this question on CNCZONE that can be found here http://www.cnczone.com/forums/diy-cnc-router-table-machines/323684-missing-steps-x-axis.html

They seem to think i am being limited by the PS/drivers. Any ideas?

Thanks
BR
bigred8080
 
Posts: 52
Joined: Sat Dec 10, 2011 10:42 pm
CNC Machine: "Book" Machine

Re: Missing Steps on the X Axis

Postby kevinl » Thu Dec 08, 2016 3:57 pm

I ran a modified book machine and could run about 38 IPM with the same 1/2" threaded rod.. don't remember my Vel. or Acc. setting.. one of my main problems was causing missed steps was large washers or collars rubbing the shield or seal on the roller bearing. I order small 1/2" slim .010 or .005 thick which helped.. I always thought that 38IPM was a good number, since 500 stepper motor RPM divide by 13 TPI would be 38.4615 IPM..

I just was not crazy about the chip load when running 35 to 40 IPM, it results in fine powder/dust when cutting..

think my driver are the CW280 or 380 ones, anyway, the typical for the NEMA23 425 oz. in. motor off a 36v 8amp power supply.. also I ran with dual x motors (one slaved).
kevinl
 
Posts: 886
Joined: Tue Feb 02, 2010 3:47 pm
Location: Birmingham, AL, USA
CNC Machine: Custom

Re: Missing Steps on the X Axis

Postby Awesomeness » Thu Dec 08, 2016 11:33 pm

You should be able to get into the 30-50ipm range. It really is true that about 90% of the problems turn out to be mechanical (something slipping, rubbing, etc.), despite the first several posts swearing it isn't. Everyone just wants to start off blaming the electronics, because they are an invisible "unknown".

How much is it getting off by?
If you don’t have time to do it right, when will you have time to do it over?
Image
User avatar
Awesomeness
 
Posts: 2881
Joined: Wed Feb 24, 2010 7:46 am
Location: Firestone, CO
CNC Machine: BlackFoot v4 4x8

Re: Missing Steps on the X Axis

Postby bigred8080 » Sat Dec 10, 2016 2:10 am

Awesomeness wrote:You should be able to get into the 30-50ipm range. It really is true that about 90% of the problems turn out to be mechanical (something slipping, rubbing, etc.), despite the first several posts swearing it isn't. Everyone just wants to start off blaming the electronics, because they are an invisible "unknown".

How much is it getting off by?


Ha, yeah, i MADE sure that all the mechanical parts were working they way they should...the best i could at least. I even ended up remaking the Z motor mount blocks.

When i first discovered it it was off by about 1/2" after running for 15 minutes or so. How i got this number is i would run a 3d roughing program for some time (air cutting) then hit the e stop and return to zero. i would be off 1/2" in the negative direction (center start).

After taking some advice from someone at work and from CNCzone i unplugged the y and z and ran the program. my problem went away. i plugged everything back in and just did some rapids in the x direction, just back and forth 10 times or so. everything seemed fine. i tried my 3d roughing again (cutting air) and everything seemed fine.

I decided to give it a go and hope for the best. I just finished the roughing and everything seemed fine. I'm about to start the finishing pass.

Maybe it was a connection and by me plugging and unplugging everythign it worked itself out? even though i didnt unplug the axis i was having problems with.
bigred8080
 
Posts: 52
Joined: Sat Dec 10, 2011 10:42 pm
CNC Machine: "Book" Machine

Re: Missing Steps on the X Axis

Postby bigred8080 » Sat Dec 10, 2016 4:46 am

Here are the results from the finishing pass. Its supposed to be a Celtic weave design created using Vectric's Celtic Weave Gadget. The steps seemed to keep up, so that was a good sign. This was cut into Oak plywood (im thinking that was the wrong choice lol) using a 1/8" Ballnose bit. I know this is a bit off topic, but what can i do to help with the rip out of the tops? The bottom portion came out great, just the centers is whats killing me. I have a single speed router...27K RPM. so i really cant do much on that end.

Image

Image

Image

Image
bigred8080
 
Posts: 52
Joined: Sat Dec 10, 2011 10:42 pm
CNC Machine: "Book" Machine

Re: Missing Steps on the X Axis

Postby bigred8080 » Fri Dec 16, 2016 1:36 am

Update:

Resurfaced my spoil board (wasn't nessacerily parallel to my gantry). This turned out better I think.

Image
bigred8080
 
Posts: 52
Joined: Sat Dec 10, 2011 10:42 pm
CNC Machine: "Book" Machine

Re: Missing Steps on the X Axis

Postby kevinl » Wed Dec 21, 2016 6:07 pm

two things you might try, one would be to try it on a solid wood piece even if you glue them together.. and second, configure the software to generate a two pass gcode, one using a rough cut (bigger bit) then finish pass with a smaller bit and slower feed rate..
kevinl
 
Posts: 886
Joined: Tue Feb 02, 2010 3:47 pm
Location: Birmingham, AL, USA
CNC Machine: Custom


Return to DIY

Who is online

Users browsing this forum: No registered users and 3 guests

cron

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