Stringy bottom

[Jules]

All my measurements are in millimeters.....yours too?

Results are what counts - if you are getting good prints, you don't need to reset the Z-stop. Just set that first layer height at 100%. (might be enough to clear up the underextrusion in the print)

[scampa123]

Yes I'm using mm...

I had it still set to 100%, but it was something I was meaning to ask you about the layer height..

I did another calibration square with the added -4 and got a bit of a glassy surface on the bottom..I keep re-testing with my caliper, so I'll play with that...

[Jules]

Good! Add yet another negative -0.04 mm to the Z-offset number and try again.

If you look at 0.04 mm on your calipers, you'll see it's almost too small to see, but that tiny bit of tuning makes a tremendous difference in the whole print. It's amazing really. I get a huge kick out of it every time i see it.

[scampa123]

Yes but if I do my print becomes too short. I'm zeroing in on 1.92mm for the height of the cube. So based on your calibration post I should add 8 to my Z offset...which at this point brings me back to -20

[Jules]

Okay, if your cube is getting shorter, that's correct, don't add any more negatives to your Z-Offset. If your current Z-Offset is -0.28 mm, the new value should be -0.20 mm in the Z-Offset slot, if your cube height is 1.92 mm.

Sticking with the formula is the quickest way to zero in on the correct number for your machine. (I was sending confusing signals earlier....my bad.)

[jimc]

many ways to skin a cat. ill toss mine out there. I have always left all my offsets at zero and first layer height at 100%. I never change my first layer gap in the software. for me it was just too easy to get screwed up from one profile to the next. to make things easy I set my z adjustment bolt up a little different. I removed it from the printer, put the jam nut on the bolt about 3/4 of the way up to the head. then I screw the bolt in from the bottom up. take a 4mm nylock nut and screw it onto the tip of the bolt so the threads are 1/2 way seated into the nylon. this way the nylock nut contacts the z switch. now I set my gap with a feeler gauge as usual and tighten the jam nut on the bottom side of the platform. this will get things really close. now you will never have to touch the bolt again. all you do when you want to tweak the gap is take a small 7mm wrench and turn the nut a little. 1/2 a flat on the nut equals about .05mm in bed gap. its very easy to make quick changes and you never have to get under the spider to loosen the jam nut or mess with the bolt. the adjustment is right there on top. if you start a print and instantly see that things need to be a little tighter then cancel the print, tweak the nut real quick and restart the print. no need to reslice.

if you really want to tune things in then you can add this to the mix.

http://www.thingiverse.com/thing:180970

[scampa123]

many ways to skin a cat. ill toss mine out there. I have always left all my offsets at zero and first layer height at 100%. I never change my first layer gap in the software. for me it was just too easy to get screwed up from one profile to the next. to make things easy I set my z adjustment bolt up a little different. I removed it from the printer, put the jam nut on the bolt about 3/4 of the way up to the head. then I screw the bolt in from the bottom up. take a 4mm nylock nut and screw it onto the tip of the bolt so the threads are 1/2 way seated into the nylon. this way the nylock nut contacts the z switch. now I set my gap with a feeler gauge as usual and tighten the jam nut on the bottom side of the platform. this will get things really close. now you will never have to touch the bolt again. all you do when you want to tweak the gap is take a small 7mm wrench and turn the nut a little. 1/2 a flat on the nut equals about .05mm in bed gap. its very easy to make quick changes and you never have to get under the spider to loosen the jam nut or mess with the bolt. the adjustment is right there on top. if you start a print and instantly see that things need to be a little tighter then cancel the print, tweak the nut real quick and restart the print. no need to reslice.

if you really want to tune things in then you can add this to the mix.

http://www.thingiverse.com/thing:180970

So you are saying you tweak the gap by turnign the nylock nut on top of the bolt and leave the bolt stationary once you've locked it in with the feeler gauge? I just want to make sure I got that right...thx

[scampa123]

Okay, if your cube is getting shorter, that's correct, don't add any more negatives to your Z-Offset. If your current Z-Offset is -0.28 mm, the new value should be -0.20 mm in the Z-Offset slot, if your cube height is 1.92 mm.

Sticking with the formula is the quickest way to zero in on the correct number for your machine. (I was sending confusing signals earlier....my bad.)

Yes, I'm going back to -20...I just cleaned my glass and am printing another Z calibration square to check it...We'll see if I'm back to 2mm on the print height...Thanks again, I appreciate all the info!

[jimc]

yes.

nothing wrong with doing it in software the way jules does it as long as that work for you. i just could never remember what was the correct offset when switching between profiles.

[Jules]

yes.

nothing wrong with doing it in software the way jules does it as long as that work for you. i just could never remember what was the correct offset when switching between profiles.

I had to set up and save separate profiles for each filament, otherwise I'd have forgotten by the next day. (On the other hand, I could never do it your way, by turning the nut, 'cause I seem to have some kind of dyslexia about which way to turn the darned thing to tighten it! )