I was cutting my first project, it was looking great. When it finished a large pocket, the spindle didn’t raise enough and appeared like it was going to move on to the second pocket. The pocket was 1" deep and looking how it tore in, it raised up around 1/4" before moving on to the second pocket.
I guess next time I’ll export these pockets as all different jobs. Can’t have that happen in oak again.
I would suggest you check your g-code in a viewer, to make sure the toolpath itself is not causing this. Then check the value of retract height you used.
I took a look at this. Technically it was moving from the 2nd pocket to the third. It finished the first pocket at Z:-2.54 and the next line of code says Z:1. When I look at the code where it finishes the second pocket it has the same kind of code. My retract height is 10mm. When do I need to change it? I’m assuming it means 10mm above where Z was set to zero so it doesn’t drag across the surface. Since the machine retracted from the first pocket, maybe the z axis belt is slipping?
Timing (toothed) Belts almost NEVER slip. What slips is
(1) the pulley on the shaft IF the set screw it not tight enough.
(2) The motor slips…it only has (about) 18 lbs of down or up force.
Check both
10mm retract is fine and yes it’s above zero anyway. Possibly Z axis slipping but strange that it happens while retracting. Check the pulley set screw maybe ?
Most likely what happened here is mechanical — the machine gradually lost steps as it was cutting the pocket, then was lower than it ought to have been when it moved over (or it lost steps on retract).
Please check the machine mechanically:
If things check out mechanically, let’s look into feeds and speeds.
checking the depth of the completed pocket will help you troubleshoot this, if its deeper than the design called for then the pulley could be slipping on the shaft. this seems the most likely issue.
I need some additional thoughts on what is normal. Is it normal for the spindle to not hold itself at the top? When the spindle is raised to the top by hand and you let go of it, it falls about a quarter inch. You can see its resting place in the first picture. If you lower the spindle more than half way it will only return to about half way up on its own. You can see this in the second picture. I’ve made sure the V wheel nuts are only barely tight enough to keep the whole z axis contraption from rocking side to side. The belt is tight, I almost feel its too tight. When looking at the machine the belt attached to the Z motor comes out at me when the spindle is pressed down and moves backwards when moving up. This causes the belt to rub against the back of the Z motor shaft as it moves backwards more than it moves forward. It causes a bit of friction when moving up but I down hear the belt slip or anything. As for it not returning up its as if the springs aren’t strong enough to return it up by themselves at least. I’m just trying to figure out if this is normal.
When the machine is powered down, yes, that is normal.
I found that by reducing the Z axis acceleration I got less slippage on my Z axis - this was back in the day when I fitted a 5kg water cooled jobby to the stock axis.
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