Help! Getting closer finally but......

[Turbojoe]

I had been using a clear 4mm glass bed from Ace Hardware (that I cut to size) with hair spray, glue sticks, painters tape and none could be truly trusted. I bought the super sticky 4mm Creality Glass bed and my adhesion problems are now finally a thing of the past. You just need to clean the bed with 91% alcohol BEFORE EVERY PRINT. Now I do much longer prints without fear of the print breaking loose. Worth every penny I spent on it!!! I also installed the newest GEETECH silent driver board, silicone bed "springs" etc. I've been getting great standalone prints but things that need to fit together properly are a no-go. I've played a bit with horizontal expansion and hole expansion and just got nowhere. Both expansion settings expand (or contact) in X and Y axis equally. What if you need a different expansion on X from that of the Y axis? Why don't they include this option?

Here is my dilemma: In TinkerCad (hold the laughter) I created a 70x25x2mm test file with 10,15 and 20mm holes. Sliced in Cura 4.13.1 The printed dimensions are "outside" 70.30X axis x 24.99 Y axis x 1.98 Z axis Holes sizes 20mm = 19.77 X axis and 19.68 Y axis. 15mm = 14.75 X axis and 14.60 Y axis 10mm = 9.55 X axis and 9.62 Y axis. WTF? Should I keep wasting filament and time playing with expansion or should I be changing axis settings with M92 codes? Or both? I need numbers to try. Not generalizations guys.

Still learning.

Joe

 

[Mr NCT]

I had been using a clear 4mm glass bed from Ace Hardware (that I cut to size) with hair spray, glue sticks, painters tape and none could be truly trusted. I bought the super sticky 4mm Creality Glass bed and my adhesion problems are now finally a thing of the past. You just need to clean the bed with 91% alcohol BEFORE EVERY PRINT. Now I do much longer prints without fear of the print breaking loose. Worth every penny I spent on it!!! I also installed the newest GEETECH silent driver board, silicone bed "springs" etc. I've been getting great standalone prints but things that need to fit together properly are a no-go. I've played a bit with horizontal expansion and hole expansion and just got nowhere. Both expansion settings expand (or contact) in X and Y axis equally. What if you need a different expansion on X from that of the Y axis? Why don't they include this option?

Here is my dilemma: In TinkerCad (hold the laughter) I created a 70x25x2mm test file with 10,15 and 20mm holes. Sliced in Cura 4.13.1 The printed dimensions are "outside" 70.30X axis x 24.99 Y axis x 1.98 Z axis Holes sizes 20mm = 19.77 X axis and 19.68 Y axis. 15mm = 14.75 X axis and 14.60 Y axis 10mm = 9.55 X axis and 9.62 Y axis. WTF? Should I keep wasting filament and time playing with expansion or should I be changing axis settings with M92 codes? Or both? I need numbers to try. Not generalizations guys.

Still learning.

Joe

I had that same problem but it was the X belt was too loose. No numbers involved, sorry.

 

[Turbojoe]

I had that same problem but it was the X belt was too loose. No numbers involved, sorry.

I've replaced the belts and printed belt tensioners for both axis. The belts are tight enough to play Stairway to Heaven on.

 

[Aslansmonkey]

So first, 3D printers are generally NOT considered precision machines. Not at the cost level that most of us pay anyway. The super expensive (tens of thousands of dollars) ones should have more precision (though I don't have explicit knowledge of this). All things considered, your printer seems pretty close to true.

I have three printers I'm running these days, an Ender 5 Pro, a Monoprice Maker Select V2 and a Delta I built myself loosely based on an FLSun design. None of these machines produce a part that's precise and they don't match each other either. If I'm going to produce parts for the same project on two or more machines I either need to print calibration objects first and note down what I have to scale things at for each printer or I just don't worry about it (because most things don't require that much precision). I sometimes have to sand things to fit. The Maker Select uses 2 steppers for the Z axis and one of them "drifts" over time forcing me to re-level the bed and manually adjust that side a little bit, though I only have to do this every 5-10 prints.

If you absolutely MUST have more precision however, there's a couple things you could do.

First in Cura you could try adjusting the settings for each part in each axis (so .995% for X, 101% for Z). That'd be tedious for each part but if you only need ONE part THAT precise, this is the easier way to go. If you go this way, first print a calibration part then for each axis take the EXPECTED length and divide it by the MEASURED length to get the percentage to use for that axis.

The other thing you could do, if you require more precision all the time, is adjust the steps per mm for each stepper motor on your printer. You'll have to look that one up but it involves similar math to the above, just used for adjusting the steps. For example, most 3D printers move at 200 steps/mm, so if you adjust your X to 199 steps and Z to 202 steps (assuming your currently at 200mm each), you should get more precision. This assumes your printers firmware even allows you to set these values. If your printer is running Marlin, the command would be M92 X199 Z202 followed with an M500 command to save the changes. They're likely is a way to set these values in the printers interface.

I left Y out of these examples because your Y axis is off by .04 percent and it's unlikely you will be able to do anything at such a small scale.

You still won't get EXACT precision, just closer.

 

[WillL84]

I just use a smooth magnetic PEI coated sheet. No needing to alcohol clean. It just works as long as your Z offset it set properly.

Once a month or something I'll take the green scotchbrite part of a sponge to it with some dish soap to get the fingerprint oils off as those will cause adhesion problems.

 

[luvmy40]

I recently watched a youtube vid about a slicer, I think it's the newest version of Cura, that alows you to adust hole diameters without effecting anything else. I.e, your drawn 15mm hole prints at 14.8 mm, you can make a percentage correction for all hole diameters and not change anything else in the X or Y aixis.

I think the vid was from Filament Friday.

Found it.

 

[Turbojoe]

I recently watched a youtube vid about a slicer, I think it's the newest version of Cura, that alows you to adust hole diameters without effecting anything else. I.e, your drawn 15mm hole prints at 14.8 mm, you can make a percentage correction for all hole diameters and not change anything else in the X or Y aixis.

I think the vid was from Filament Friday.

Found it.

Yep. I watch Chuck too. I'm using Cura 4.13.1 and now have my outer dimensions dialed in with steps/mm and am now almost there with hole expansion On a 30x30x2 with 20mm hole. (prints so much faster). I've seen Chuck with perfect print sizes on the same Ender3 as mine. I know it's possible and I'm not happy with "close enough". I've printed tons of standalones where precision wasn't important. There are things I want to print that MUST fit together properly.

 

[luvmy40]

I'm glad I haven't run into this with my Ender 3 Pro's. My wors't problem is cleaning up the stringing with PETG. The prints are great, near perfect, but I can't seem to get rid of the stringing. PLA runs perfectly, but I need the PETG Strength.

Have you tried PLA+ for anything?

 

[Turbojoe]

After about 3 hours printing, adjusting and 4 miles of filament I finally have everything dialed in to my satisfaction. Within .01mm on only X axis. Y axis is dead nuts zero. Now THAT'S close enough to make me happy. I couldn't live with the .06 and greater outside that I had before and WAY,way OFF for holes. Now I feel confident to print the 70mm EDF nacelle files that will take well over 15 hours.

luvmy40: I do have a roll of red PLA+ but haven't opened it yet. I still have 3/4 roll of red PLA that I need to use up before I open it. I do have a vacuum sealer but I just hate to open rolls until needed.

Joe

 

[Turbojoe]

While I don't have a bloody clue what I'm doing I'm learning a lot only at the expense of some time and filament. I just installed Cura 5.0 BETA. Loving it! Now my holes in the 32x90x2 test piece w/20,15,10mm holes are too small by .28mm but the holes are 100% concentric! I can easily dial that out with hole expansion. Also the outside dimensions are slightly smaller. Again, I can dial that out with steps/mm adjustments. Will likely have to go back to factory settings that I had to change for Cura 4.13.1. I'm getting excited now.

Joe

 

[quorneng]

Turbojoe
Remember as far as the printer is concerned any dimension you set is to the centre line of the bead being laid down. This means a hole with a 10 mm radius will actually have a radius reduced by half the thickness of bead, most of the time!
Setting up printed parts to be an accurate fit can involve a bit of trial and error. Once you have the numbers required fit the printer should be able to reproduce it every time to within the repeatable accuracy of the machine, likely 0.05 mm.

 

[WillL84]

Turbojoe
Remember as far as the printer is concerned any dimension you set is to the centre line of the bead being laid down. This means a hole with a 10 mm radius will actually have a radius reduced by half the thickness of bead, most of the time!
Setting up printed parts to be an accurate fit can involve a bit of trial and error. Once you have the numbers required fit the printer should be able to reproduce it every time to within the repeatable accuracy of the machine, likely 0.05 mm.

The Slicer sets the toolpath to the demsions are replicated the best. This means that it won't set the tool path to the centerline of the bead, rather it'll offset it to the right or left as needed. Same thing with CNC machining. It will offset the toolpath by the tool radius to get the desired part shape.

 

[quorneng]

WillL84
I am sure a CNC cutting machine takes into account the cutting tool dimensions but my printer certainly does not do so accurately, if at all, with the print bead.
In my experience to create a specific type of 'fit' between two printed components requires a degree of dimensional trial and error.

 

[WillL84]

WillL84
I am sure a CNC cutting machine takes into account the cutting tool dimensions but my printer certainly does not do so accurately, if at all, with the print bead.
In my experience to create a specific type of 'fit' between two printed components requires a degree of dimensional trial and error.

That's the slicer's job though. You'll always have real world variations though of course. But the slicer's job is to take the 3D model and use the selected nozzle size, extrusion width, etc. to best replicate that model. If it didn't take extrusion width into account then everything would be incorrectly sized - exterior dimensions would be 0.4mm too wide (assuming a 0.4mm layer width - 0.2mm for each side). However if you design a 50mm cube and then print it it'll most likely be 50mm and not 50.4mm.

 

[quorneng]

Just out of curiosity what would expect the dimensions to be of a 'vase' printed (single wall) tube of a say 50 mm diameter. 50mm ID or OD?

 

[WillL84]

Just out of curiosity what would expect the dimensions to be of a 'vase' printed (single wall) tube of a say 50 mm diameter. 50mm ID or OD?

You know, that's a good question. I reckon I'll try that. My guess is the OD would be 50mm as vase mode parts are typically hollow

 

[Turbojoe]

I'm finding after re-slicing STL's with Cura 5.0 Beta that all my previous settings/adjustments in 4.13.1 sliced files are a bit off now in 5.0. I've reset all of my steps/mm to factory X=80 Y=80 Z=400mm and will need only very minor adjustments from there. Once I have that down to gnat's ass perfect, I'll work on getting the holes just as perfect. I know it's a long shot but I'm obviously a glutton for punishment and plan to keep at this. I'm sick and tired of multiple items for a single assembly design just not fitting together properly. So far Cura 5 looks like the best chance of my achieving usable fit every time.

I'm looking forward to the final release of Cura 5.0!

Joe

 

[Turbojoe]

For me CURA 5.0 BETA is the BOMB! To get accurate prints from 4.13.1 settings I had to set all steps/mm pretty much back to factory settings with maybe a .01mm change for what is perfect for me. No other changes made in Cura other than some slight hole expansion tweaks. Even printing at .028mm my prints are smooth and really pretty. Ironing the top layer would make it look even better. I created a desktop smartphone holder "kit" in TinkerCad and am doing the last few small parts prints. So far everything sizes and fits perfect.

I now have so much more confidence in my very early production Ender 3 (bought it the day it first showed on Amazon) printing usable parts. Now if I only knew what the 867 other settings in Cura did I'd be in great shape. Still LOT'S of learning in store for me.

Joe

 

[Turbojoe]

OK, so I was getting great prints after upgrading to Cura 5.0 beta but didn't truly understand why. I was using CURA 5.0 with a 4.13.1 config with some very minor adjustments. I decided to start with a clean 5.0 file and adjust from there as I'll be using 5.0 from now on. For the sake of fast printing I'm using a self created 30x30x2mm w/20mm hole. With a clean Cura 5.0 file my print is X=29.88 Y=29.88 Z=2.08 The hole is 19.83 concentric. I had noticed some very slight stringing before starting off "clean" again. Now the stringing is gone. I do have "bumps" at each corner that are .38mm larger than the area between those "bumps". I can cut or sand them off but I'd prefer to learn what to change to eliminate them. I want to eliminate those bumps first and then go on to making adjustments to the printer and Cura to get all my printed dimensions back to where I want them again. Based on my "bumps" what would you change? After I get that done then I'll again make the steps/mm and expansion adjustments as needed. Learning by doing always works best for me.

Joe

 

[Mr NCT]

OK, so I was getting great prints after upgrading to Cura 5.0 beta but didn't truly understand why. I was using CURA 5.0 with a 4.13.1 config with some very minor adjustments. I decided to start with a clean 5.0 file and adjust from there as I'll be using 5.0 from now on. For the sake of fast printing I'm using a self created 30x30x2mm w/20mm hole. With a clean Cura 5.0 file my print is X=29.88 Y=29.88 Z=2.08 The hole is 19.83 concentric. I had noticed some very slight stringing before starting off "clean" again. Now the stringing is gone. I do have "bumps" at each corner that are .38mm larger than the area between those "bumps". I can cut or sand them off but I'd prefer to learn what to change to eliminate them. I want to eliminate those bumps first and then go on to making adjustments to the printer and Cura to get all my printed dimensions back to where I want them again. Based on my "bumps" what would you change? After I get that done then I'll again make the steps/mm and expansion adjustments as needed. Learning by doing always works best for me.

Joe

Thanks for sharing your setups. You started this thread to get help but your process has helped me get better prints.