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501  General CNC Chat / Show"N"Tell ( Your Machines) / Re: AL54b (lathe) project from New Zealand on: June 14, 2011, 07:28:47 AM
Not quite so. Lead screws can be very accurate. Not sure what are the numbers you measured. It is common to speak of a ball screw in terms of accuracy over a given length. Thus, for instance, a C5 accuracy grade would mean about 0.03mm acceptable error in travel over 300mm. Accuracy grade definition varies from one manufacturer to another, so the above example is not dictated by a standard.

Lead screws can easily hold those accuracies. So, when using ball screws it's not really an accuracy demand. Ball screws allow you to have minimal backlash (practical zero), which is often desired in a CNC application. Also, ball screws run quieter and higher speeds can be achieved without the risk of heating the nut and wearing it. Of course they wear slower. Theoretically you can have a lead screw set up to have zero backlash, but it will hardly last.

Dan

EDIT:

Forgot your lathe was Chinese, so the original screws may have been poor quality and not as accurate Wink
502  General CNC Chat / Show"N"Tell ( Your Machines) / Re: AL54b (lathe) project from New Zealand on: June 10, 2011, 12:58:41 AM
Isn't it so much rewarding to finally see it in action Smiley

I like the G251 - it almost makes steppers sound like servos. Still not on all speeds though.

Dan
503  Mach Discussion / Machscreen Screen Designer / Re: MachScreen releases on: May 25, 2011, 10:44:50 AM
Thank you, Klaus!

Dan
504  Mach Discussion / Machscreen Screen Designer / Re: MachScreen releases on: May 21, 2011, 02:26:05 AM
Great!!

Dan
505  Mach Discussion / Machscreen Screen Designer / Re: MachScreen releases on: May 21, 2011, 02:09:38 AM
Hi Klaus,

We have just found with Hood that there is something that can be very useful which can be done in Screen4 but not in MachScreen. In Screen4 one can force leading zeros by using a formatting string something like this %04.0f. MachScreen on the other hand, doesn't output leading zeros with the same formatting string.

Also, using a formatting string like T%04.0f is allowed in Screen4 and and will output the T in front of the number. This is useful in some cases, like the one demonstrated by Hood, here:

http://www.machsupport.com/forum/index.php/topic,17093.msg127574.html#msg127574

Please consider adding these capabilities to MachScreen.

Thank you for your efforts and a great software!

Dan
506  Tangent Corner / Bargain Basement / Re: Back Covers For Stepper Motors on: May 18, 2011, 08:22:39 AM
Hi Peter,

That looks neat! Thanks for posting it.

Dan
507  General CNC Chat / Show"N"Tell ( Your Machines) / Re: The Laser Project. on: May 15, 2011, 02:37:11 AM
Amazing!

Dan
508  Mach Discussion / General Mach Discussion / Re: Mach3 is not talking to Breakout board on: April 21, 2011, 04:30:36 AM
If you're measuring at the PP output it would be around 0V in its low state and around 5V (or 3.3V depending on your PP card) in its high state.

Dan
509  Mach Discussion / General Mach Discussion / Re: Mach3 is not talking to Breakout board on: April 21, 2011, 12:31:57 AM
Since the step line is a square wave, and not a constant DC (nor a 50Hz AC), the voltmeter will show just "something" based on its interpolation technique. It is not a value to judge by the output correctness. But since the value does change, you can tell that signals do go out of the breakout board.

Dan
510  Mach Discussion / General Mach Discussion / Re: Mach3 is not talking to Breakout board on: April 16, 2011, 10:48:07 AM
Hmm.... I remember someone was having a problem with lost steps here and he was reporting that his direction pins' state was not changing, but rather he was seeing pulses on the direction lines. It's an abnormal condition (don't remember if he reported/found the cause), but may be it's what you're having. Can you try measuring the spindle relay output? Try to toggle the spindle ON and OFF and see if it changes state.

Otherwise, looks to me like you're printer port is not functioning properly. May be reinstalling it or something could help...

Dan
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