Bridgeport conversion video.

[nate]

The X axis is just mocked up. Mounted, but just so. not even close to what it will look like when done. everything was mounted just well enough to see if I had enough power/reduction to really move this heavy table around.

Seems to be working!

YouTube - BridgeportCNCXTest1

YouTube - BridgeportCNCXTest1

[JHCHOPPERS]

Looks like your off to a good start !

[nate]

Ok, I have found something interesting while doing more X axis testing.

It seems that the only time I am losing position is when the axis abruptly stops (E stop for example)

My best guess is that the monster Browning 44 tooth pulley has a significant flywheel effect. I have thinned down the pulley on my lathe significantly, but I am still having it (through inertia) carry a few steps (mabie more) past its intended stop. I must stress that this never happens when the Gcode tells it to stop (due to the ramping down of the speed in preparation for the stop.

I am going to switch the motor pulley out tomorrow for a 14 tooth, replacing the 20tooth thats currently on the motor. I theorize that the flywheel effect of the 44 tooth pulley will be less likley to overpower a smaller (14tooth) motor pulley.

Another thing worth noting is that I am having these Estop position losses when I am doing this testing at 140 IPM, much faster than I am likley to be machining at. I suppose that the lower the IPM, the less the rotational inertia thus it should be much less likley to overpower the stepper motor and lose its position.

Anyone have any thoughts?

[HimyKabibble]

Originally Posted by nate Ok, I have found something interesting while doing more X axis testing. It seems that the only time I am losing position is when the axis abruptly stops (E stop for example) My best guess is that the monster Browning 44 tooth pulley has a significant flywheel effect. I have thinned down the pulley on my lathe significantly, but I am still having it (through inertia) carry a few steps (mabie more) past its intended stop. I must stress that this never happens when the Gcode tells it to stop (due to the ramping down of the speed in preparation for the stop. I am going to switch the motor pulley out tomorrow for a 14 tooth, replacing the 20tooth thats currently on the motor. I theorize that the flywheel effect of the 44 tooth pulley will be less likley to overpower a smaller (14tooth) motor pulley. Another thing worth noting is that I am having these Estop position losses when I am doing this testing at 140 IPM, much faster than I am likley to be machining at. I suppose that the lower the IPM, the less the rotational inertia thus it should be much less likley to overpower the stepper motor and lose its position. Anyone have any thoughts?

You *are* going to have that problem when you hit E-stop, unless it's moving very slowly. The intertia of the table will see to that. E-Stop is to be used only for emergencies, as it simply stops issuing step pulses, without doing *any* deceleration ramp. With steppers, that means lost steps. Lighten the pulley all you like, it won't fix that problem as long as you're using steppers.

Regards,
Ray L.

[nate]

YouTube - MVI 3409

YouTube - MVI 3409

Video part 2.

[nate]

http://i572.photobucket.com/albums/s...nroom101/1.jpg
http://i572.photobucket.com/albums/s...nroom101/2.jpg
http://i572.photobucket.com/albums/s...nroom101/3.jpg

[Hayworthmilling]

Hm, that is a big screw.

[BrooksMachining]

Originally Posted by Hayworthmilling Hm, that is a big screw.

Reminds me of last night

[nate]

YouTube- MVI 3423

YouTube- MVI 3423

[Goldhunter_2]

cool now if you just lived near me to walk me though making my mill cnc ..lol

no seriously though it looks like your making great progress