¿ªÔÆÌåÓý

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. MachCNC
  2. Topics

Backlash

 

Hi All:

Before I start this I should say that my "Manual" is not the latest update--printer is too tired to print that out often.

My MDF Router has Backlash (surprise). 006" on "X", 009" on "Y" and 006" on "Z"

Not too bad for cutting Balsa, but can I do better? I tried entering these figures in the "Configure Backlash" page, but my measurements, via MDI haven't changed. I still have the same Backlash. I'm satisfied that I'm measuring it correctly and it's consistent.

My Manual gives very little info on "Backlash" compensation. I have absolutely no idea what "Backlash Speed % of Max" means nor what it does.

Should I just leave "Well enough Alone" or play some more?

Thanks again

John Bell
Art
 

Hi John:

YOu must trun on backlash on the state config. Unless its on you'll have no
change. The backlash is adjusted in the background and the correction takes
place when an axis reverses movment. This means constant Velocity should not
be used. Play with it a bit and see how well it works for you.

Good luck,
Art
www.artofcnc.ca
 

-----Original Message-----
Hi John:

YOu must trun on backlash on the state config. Unless its on
you'll have no change. The backlash is adjusted in the
background and the correction takes place when an axis
reverses movment. This means constant Velocity should not be
used. Play with it a bit and see how well it works for you.

Good luck,
Art
www.artofcnc.ca

Art,

You always mention that backlash should not be used with constant
velocity.Not sure I understand why? I know I have run EMC with constant
velocity and backlash and it works perfectly. So why is it you talk
about the 2 features as being mutually incompatible?

Tim
[Denver, CO]
Order Sherline now before the Oct 1 price increase.
Sherline & Taig products at Deep Discount
Mach1 & DeskCNC with credit card ordering
www.KTMarketing.com/Sherline
e-mail me at Timg @ KTMarketing.com for items not yet listed
Art
 

Tim:

In theory, they are not mutually incompatible. But in practice, it depends
highly on the hardware used. Picture a two axis interpolated circle, when
the X axis hits its 90 boundry, it must correct before the Y axis can
continue. This means the X axis must move a particular distance prior to the
Y axis taking the next step. Now if you have only a pulse or two of
backlash, you copuld probably apply it quickly, and the Y axis would not
notice the pause. But if the correction is too large, or the time of
correction too long due to slow corrections, then the Y can lose steps
because it has not slowed down enough to allow for the pause in pulseing on
its axis while the X does its correction.

I have seen system that show no effect from backlash, and I have also seen
the reverse. CV is affected in this because of its assumption that its OK
for Y to be going at speed when the X reverses fopr backlash correction. I
think even in EMC, if you up the pulse count of the backlash, you'll find
you lose steps. This is something that differs from user to user, so I
always advise that they are incompatible, though they are not always.

Art
www.artofcnc.ca

1 - 4 of 4