X vs Y accuracy adjustments

I'm (trying to) make camera lens adapters - for this application accuracy is pretty important.

Aside from material shrinkage, I see my M200 parts are slightly smaller in the X dimension than in the Y dimension - roughly by 0.4%. (I haven't measured Z accuracy.)

I suppose this ultimately mechanical, but it seems like an easy thing to adjust for either in firmware or in Z-Suite (just use a constant to increase/decrease X movement by the given correction factor).

Is there a way to do this? Can it be made available in the future?

Ideal, I suppose, would be separate correction factors for X, Y, and Z for each material separately - that would allow correction for both mechanical error in the printer and shrinkage for each material.

See images - the part is supposed to be perfectly round.

In Z-Suite you can do a scale operation (http://support.zortrax.com/z-suite-manual/ - see step 8), but note the scaling operation applies to the local coordinate system of the part, not the machine coordinate system; if you reorient a part in z-suite, you must also then translate the x-y-z scale factors for the rotation of the part. For the specific part you show, you can alternatively use the contour offset.

That's a start. 

If a standard set of X, Y, Z correction factors could be stored in Z-Suite (one set for each material, since each shrinks a different amount), then Z-Suite could apply those automatically when slicing, according to the material chosen.

That would correct for both material shrink and any tiny differences in X, Y, Z motion all at once.

Of course you'd have to print out a calibration piece and then measure it carefully to get the correction factors (since I assume each machine might be slightly different).

Right now I'm looking into doing it myself in SolidPython (a Python pre-processor for OpenSCAD; highly recommended!).

Still, it would be nice if Z-Suite did it - then you could be sure that all parts would be printed as accurately as your machine physically can.

Did you sand down the seam before you took the measurement? Just want to make sure since the seam usually protrudes a bit...and on your pic with the larger diameter the caliper sits right on the seam...

You have a lot of ghosting in your object. My prints do not have the ripple effect around the numbers that I see in your image.

FYI scaling I dont think is working correctly in 1.8.1 as it's rounding to nearest integer. From what I can see of your part, offset option in advanced menu should work, or use older version of z-suite, or scale stl before importing. I filed issue in bug tracker.

You have a lot of ghosting in your object. My prints do not have the ripple effect around the numbers that I see in your image.

Maybe set in normal mode? Another possibility maybe belt tension too low.

@Andre: Yes, I accounted for the seam. However I've since noted that the X vs Y scaling issue seems to vary a bit from print to print - it's not as bad on subsequent prints as it was on that one.

@Brett90, @ChunkyPastaSauce: Not sure what you mean by "normal" mode. Normal vs Random start? I tried that - Random didn't get rid of the seam, it just moved it to a different (random) place on each print.

Any suggestions re dealing with the ghosting would be really welcome. (Altho the effect was exaggerated by the lighting in the photos.)

Re the overall scaling issue, I'm making good progress calculating correction factors and applying them in SolidPython. At this point I can reliably get prints to come out within 100 microns of the intended size (Z-ULTRAT); I think I can get it to 50 or less with a bit more work.

There seem to be 2 factors involved - a multiplicative (scaling) one, and an additive one (bleed).

At edges and thin walls, the material seems to "bleed" a bit, making thin walls thicker than intended - by roughly 0.05 +/- 0.01 mm (50 microns) per side. So I'm simply subtracting that amount from critical end dimensions. (Again, that's with Z-ULTRAT; I haven't yet tried calibrating with other materials, but I have some Z-ABS and Z-PETG to try...)

Overall there seems to be shrinkage of the the entire part by about 0.5% +/- 0.1% (Z-ULTRAT); a little more in X than in Y (which tells me it's not all material shrinkage; some is inaccuracy in the printer mechanics). Again, I'm calibrating to get the exact numbers so I can correct for them.

Once I've got it all worked out, I'll post something here and on my blog (nerdfever.com) about how to do it. With all the corrections in, the M200 can produce remarkably accurate dimensions.

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If anybody here uses SolidPython, see this related thread: https://github.com/SolidCode/SolidPython/issues/68

@Andre: Yes, I accounted for the seam. However I've since noted that the X vs Y scaling issue seems to vary a bit from print to print - it's not as bad on subsequent prints as it was on that one.

@Brett90, @ChunkyPastaSauce: Not sure what you mean by "normal" mode. Normal vs Random start? I tried that - Random didn't get rid of the seam, it just moved it to a different (random) place on each print.

Any suggestions re dealing with the ghosting would be really welcome. (Altho the effect was exaggerated by the lighting in the photos.)

....

At edges and thin walls, the material seems to "bleed" a bit, making thin walls thicker than intended - by roughly 0.05 +/- 10 mm (50 microns) per side. So I'm simply subtracting that amount from critical end dimensions.

Normal was referring to the quality setting.  Normal (instead of High) quality setting increases ringing you'll see on the part, as well as possibly the bleeding you describe.

Make sure the table is set as low as possible during calibration, if it's near the ends of the adjustment screws the table will be sitting on stilts

Setting low infill can improve accuracy (particularly models with thick sections), side covers (larger parts).

Z-PETG has lower shrink, but have only printed a few times with it so can't comment on it.

Got it. I've been printing on "high" quality, minimum layer height, and "high" infill all the time (so far).

I'll try recalibrating at the bottom of the screws - maybe that'll help a bit. (Tho the ringing is only a cosmetic bother; it doesn't affect functionality for what I'm doing.)

I bought the Z-PETG (and tried printing a few things with it) for the low shrinkage, but then decided stiffness was more important for what I'm doing than shrinkage - I can calibrate the shrinkage away. (Working on it, anyway.)

So I switched to Z-ABS (indeed stiffer), and now Z-ULTRAT. I note Z-ULTRAT parts come off the raft much easier than the other materials. Not sure if it's any stiffer than Z-ABS - I may go back to Z-ABS.

If you're looking for maximum stiffness, z-glass is like 1.5x-2x everything else.

Make sure to set the maximum top and bottom layers, use latest z-suite and set bottom layers to max (usually 6); outer most material from axis of bend usually has greatest effect on bending stiffness.

Also I know strength is influenced by layer height (usually medium-large layering stronger than small), would not be surprised if stiffness is as well and in same direction

Unfortunately, transparency is not a good thing in lens adapters. (They need to be opaque.)

I was under the (mistaken?) impression that Z-GLASS and Z-PETG were the same material, except for color. At least, the properties table on the Zortrax website (https://zortrax.com/materials/zortrax-m-series/) makes them look identical, right down to identical resistance to "salts acids alkalis".

So I bought black Z-PETG. But that table shows both Z-PETG and Z-GLASS have less hardness than Z-ULTRAT, so I'm guessing Z-ULTRAT is stiffer.

Playing with the parts in my hands, Z-ABS seems stiffer than either one. But I haven't measured deformation under load.

Yeah I was thinking a semi-transparent lens cap might look too weird (but probably functionally?).

Z-Glass and Z-PETG are related but very different as Z-Glass is glass fiber filled (~10%) PETG; the glass fibers substantially increases material stiffness.

https://zortrax.com/wp-content/uploads/2016/10/Z-PETG_Material_Safety_Data_Sheet.pdf- see composition

https://zortrax.com/wp-content/uploads/2016/10/Z-GLASS_Material_Safety_Data_Sheet.pdf

https://zortrax.com/wp-content/uploads/2016/10/Z-GLASS_Material_Data_Sheet_eng.pdf-see "flexural modulus" which is the stiffness under bending

https://zortrax.com/wp-content/uploads/2015/10/Z-PETG_Material_Data_Sheet_eng-3.pdf

Hardness has multiple meanings. I think on the website material table, in that case the hardness is referring to the tactile feel thing/scratch resistance. However, if you look at the measured rockwell hardness of PCABS (marked high hardness on site) and HIPS (marked low hardness on site), the rockwell hardness is basically the same (but the scratch resistance of HIPS is much lower).

https://zortrax.com/wp-content/uploads/2015/12/Z-PCABS_Material_Data_Sheet_eng-2.pdf

https://zortrax.com/wp-content/uploads/2016/10/Z-HIPS_Material_Data_Sheet_eng.pdf

I'd probably print a LOT of z-glass because of the mechanical properties, but unfortunately z-glass is the least reliable material to print due to nozzle clogging.

The lens caps are just practice/calibration. The real goal is lens adapters. While lens caps only need to keep the dust off, lens adapters need to be totally light-tight.

Ideally, also flat black, so reflections don't bounce around internally.

Which is too bad, if Z-GLASS is really stiff.

Maybe two parts? Z-glass structural part (adapter) and an internal or external black sleeve.

I too made a lens adapter (for a canon 5D mark III)

Model I made:

8p1kQ8a.png?2

Attached to camera, with metal front plate:

6R7Qz15.jpg?1

Major issue I found with z-abs is it's too soft, it wears when mounting/dismounting (because the lens mount has a pressure spring to keep the mounting flange preloaded with the lens). The result is black material ending up inside the camera housing (and I think the locking pin will wear out at some point). So you might want to try with one of the harder materials to prevent that. One option is to find an old lens, and remove the mounting plate (or buy a plate) and screw to the printed adapter (I ended up doing this on the lens side, see pic).

That's an excellent idea about stealing the metal mount flange from an old lens. I can do that easily for Canon EOS (easy to find old cheap lenses), but not so easy for Pentax Q mount (which is what I want to mount things on, mostly - because it has a very short flange focal distance; only 9.2 mm).

But maybe I can buy a Q adapter on eBay and use that...great idea!

The black sleeve idea is good too, but perhaps it would be a bit tricky to get the exact correct length. If it's too short light could get around the ends (too big doesn't fit). Maybe with a black gasket or O-ring...

Can you share that EOS mount model? It looks like a handy thing to have!

BTW, off-topic - I see a lot of people online using 2 fans with their M200. Is that a good idea? Would it improve print quality with standard Z-materials? (I'm not really interested in fiddling with non-standard materials if I can avoid needing to.)