Z fine-adjustment without tools

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Re: Z fine-adjustment without tools

Postby canadianavenger » Thu Jan 24, 2013 3:10 pm

orcinus wrote:I'm amazed with the lengths to which people are willing to go to make their bottom Z endstop adjustable without tools.
Instead of just using a top endstop and adjusting the bottom one in software ;)


And if software becomes out of sync with reality because of lost steps, you can crash your head, whereas the endstop will help prevent this by "advertising" the lower limit.
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Re: Z fine-adjustment without tools

Postby SystemsGuy » Thu Jan 24, 2013 3:17 pm

The theory of "top" endstops is sound, and I use it on my delta bot. I also have my z travel at 1000mm/s on the Z, so getting from top to bottom takes seconds.

Takes just a *bit* longer to screw and unscrew the same distance on the OrdBot.

orcinus wrote:I'm amazed with the lengths to which people are willing to go to make their bottom Z endstop adjustable without tools.
Instead of just using a top endstop and adjusting the bottom one in software ;)
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Re: Z fine-adjustment without tools

Postby flurin » Thu Jan 24, 2013 5:17 pm

SystemsGuy wrote: I also have my z travel at 1000mm/s on the Z, so getting from top to bottom takes seconds.


1000 mm/s? that means 0.15s for 150mm

probably 1000 mm/min, also 9s for 150mm
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Re: Z fine-adjustment without tools

Postby SystemsGuy » Thu Jan 24, 2013 5:46 pm

Z's 760mm. I'll don't have a video of mine handy, so one of Johann's will have to do. Homing is at 1.03 - moving mass on my printhead is about 50 grams.
EDITED : Oops, wrong video! ;-) Here's the right one.







flurin wrote:
SystemsGuy wrote: I also have my z travel at 1000mm/s on the Z, so getting from top to bottom takes seconds.


1000 mm/s? that means 0.15s for 150mm

probably 1000 mm/min, also 9s for 150mm
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Re: Z fine-adjustment without tools

Postby orcinus » Thu Jan 24, 2013 7:31 pm

canadianavenger wrote:And if software becomes out of sync with reality because of lost steps, you can crash your head, whereas the endstop will help prevent this by "advertising" the lower limit.


That's the canned answer i always hear when i mention top endstops.
Unfortunately, it has very little basis in reality.

If you're skipping steps, you've got more problems than a "crashed head". Also, a lost step or two (or three or four or five) can hardly be called a "head crash". Think about it. After touching the bed with the head, you can go a further 0.3-0.4mm even with a completely fixed bed, without any trouble. 0.3-0.4mm equals about 760-1000 steps.

But even ignoring that (as hard as 760-1000 steps are hard to ignore), the Z current on my setup is set so it cannot do any damage even if it continued pressing against the bed until i hit the kill switch. And that's with an Arcol.hu head, one of the least sturdy heads available.

And even ignoring THAT, i have it set up so it lowers the head about 1-2mm above the bead after a home. And then i hit the -Z button a few times and issue G92 Z0. Which is 4-5 mouse clicks that ALWAYS guarantee that the Z is adjusted right, compared to spending days designing mechanical Z adjustment setups and then fiddling with thumbscrews.
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Re: Z fine-adjustment without tools

Postby flurin » Thu Jan 24, 2013 7:35 pm

@SystemsGuy

Ok, it's a delta bot :!: , I didn't read all your comment.
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Re: Z fine-adjustment without tools

Postby flurin » Thu Jan 24, 2013 7:46 pm

@Orcinus
What's your problem? If you prefer to use the mouse instead of using an adjusting screws it's ok.
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