Setting the First Layer Width to Match the Other Layers

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Setting the First Layer Width to Match the Other Layers

Postby FoxWhal » Mon Apr 20, 2015 11:03 pm

Beginer question I know, but I'm having trouble with the first layer being wider than the subsequent layers. I'm trying to print a phone case with text punched out of the back, but the wide first layer is covering the text so it can't be seen. Any suggestions?

I'm printing PLA, using Simplify-3D
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Re: Calibrating the Z-Offset

Postby Jules » Tue Apr 21, 2015 12:04 am

Yeah, if you're squishing the first layer, you have the Z-stop set with the bed too close to the nozzle for that filament.

Calibration is the best way to fix it, and it needs to be done at least once for each spool of filament, because I've found that it changes quite a bit, even between rolls by the same manufacturer. The various colorants/additives/water content/etc. in the plastic just make each thread extrude a bit differently.

Since I switch back and forth between colors and manufacturers several times daily, I don't want to mess with re-setting the Z-stop every single time. It would take forever.

So I cheat. ;)

I set the Z-stop height once using a feeler gauge, (.006" or .15 mm), while the bed and nozzle are heated up to filament temperature, then make adjustments in S3D based on the size of the calibration square for each spool of filament. Jin's write-up of Ed's calibration routine can be found here:

http://forum.makergear.com/viewtopic.php?f=3&t=1964

In the G-Code section of the printing parameters in S3D, there is a Z-Offset slot. After I print the first calibration square, I measure the height with calipers, subtract it from 2.0 mm and then enter that number into the Z-Offset slot for that spool. (If the square is not tall enough, you'd enter a positive number, if it's too tall, you'd add a negative adjustment.) A positive number moves the bed farther away from the starting point for the first layer, so that the thread gets laid down evenly instead of getting squished out. A negative Z-Offset adjustment number brings the bed in closer before printing, so that the thread can stick to the plate.

I run a second and maybe third square, just to fine-tune it, until I get a square exactly 2.0 mm tall. (Or within the tolerances of my extremely squidgy calipers.) I've discovered that i usually have to back off the initial adjusment by -.03....don't know why, I just do.

After that, i calibrate for the extrusion width according to the steps outlined in Jin's post using Ed's instructions.

Last step is to change the number of layers and infill to what you usually use, and then Export the S3D settings for that spool, so you can just switch to that profile when you pop on that roll.

It sounds like a lot more work than it is - each spool usually just takes a few minutes to calibrate, and the guys did a fantastic job explaining it. You'll get great prints as a result...(unless you are using a spool with a lot of variation in the filament width. But that's another problem.)

And it really keeps you from over-extruding that first layer. I got lazy the other day switching to a new roll and didn't bother to calibrate it first.....that was a mistake. That print wound up with a sharp little skirt as a first layer, that had to be tediously filed off.

Hope that helps some! :)

calibration.stl.zip
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Last edited by Jules on Thu Sep 24, 2015 6:46 pm, edited 6 times in total.
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Re: Setting the First Layer Width to Match the Other Layers

Postby FoxWhal » Tue Apr 21, 2015 12:59 am

Thanks so much for the thorough reply!
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Re: Setting the First Layer Width to Match the Other Layers

Postby Jules » Tue Apr 21, 2015 2:13 am

My pleasure.....just paying forward the excellent information provided by those who came before me. :D
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Re: Setting the First Layer Width to Match the Other Layers

Postby jsc » Tue Apr 21, 2015 3:04 am

Jules wrote:Or within the tolerances of my extremely squidgy calipers.


That reminds me, I just took delivery of a Mitutoyo 500-196-30 after a year of using a $10 Lowes' plastic caliper. The difference in feel is just night and day. I can get repeatable measurements every time, and it never needs to be re-zeroed. It's not cheap, but I was getting a lot of use out of my plastic one and figured a nicer one would be worth it to me.
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Re: Setting the First Layer Width to Match the Other Layers

Postby Jules » Tue Apr 21, 2015 3:20 am

Holy Guacamole Batman! I'd better put in a request for a set of birthday calipers, 'cause much as i'd love to have them, I'm too cheap to buy them for myself! :D

(Still, you do get what you pay for.....)
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Re: Setting the First Layer Width to Match the Other Layers

Postby jimc » Tue Apr 21, 2015 3:41 am

you know its funny. while i havent had any cheap plastic calipers i do have 2 pairs of cheap stainless import calipers. one digital and one dial. i dont think i paid more than 20 bucks for each one. i have had the dial one for 15 years and its dead nuts on the money every time. maybe i just got lucky with it, i dont know. i measure something with either one then check it with a friend's very expensive set and they both read the same. i am usually the one to buy the most expensive tool available but i really did right with these ones. i have no complaints at all. having a good set of accurate measuring tools is a must if your 3d printing or designing.
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Re: Setting the First Layer Width to Match the Other Layers

Postby Jules » Tue Apr 21, 2015 4:00 am

LOL! You should most assuredly play the lottery jim! :D
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Re: Setting the First Layer Width to Match the Other Layers

Postby FoxWhal » Tue Apr 21, 2015 11:32 am

I have the digital import callipers which seem to be working so far. The irony of avoiding the plastic ones isn't lost on me!

One follow up question on the cal technique. If measuring the thin wall prior to correcting the z offset, I assume I shouldn't measure the fatter part of the wall that resulted from the first layer, but just the upper layers?
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Re: Setting the First Layer Width to Match the Other Layers

Postby PcS » Tue Apr 21, 2015 11:51 am

Yes just the upper layers. Another thing to look at in s3d is the first layer height.setting . Mine is set at 140 percent For improved first layer adhesion And it can be tweaked when changing layer heights regularly to avoid constantly adjusting z height. Also you can check infill extrusion width can effect this as well .
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