Help! Inaccurate 3D print sizes!

Turbojoe

Elite member
I have a high quality machinists straight edge. If I feel better tomorrow I may take the whole damned thing apart and check every rail to ensure they're all straight.

Joe
 

chrisvdv

Active member
Have a look at posts 1567 to 1570 in the 'SPIT' Roasted FB thread. I am feeling for you so this may just be the answer. (To be honest I am not into 3d printing, but follow the threads and posts to try and gain some insight into it.)
Hope you nail it, just keep on trying.
 

Notnewton

Member
Joe,
I have an ender3 as well. I had similar issues that got worse over time due to the filament wearing the hole through the extruder arm. I ended up replacing the plastic extruder with one of the cheap red ones and my problems went away. If this is your issue you will be able to see that the hole where the filament goes into the extruder arm is no longer round. I hope this at least gives you one more item to rule out.
 

Turbojoe

Elite member
Have a look at posts 1567 to 1570 in the 'SPIT' Roasted FB thread. I am feeling for you so this may just be the answer. (To be honest I am not into 3d printing, but follow the threads and posts to try and gain some insight into it.)
Hope you nail it, just keep on trying.

Thanks! I watched the outstanding YouTube build video from Tomb of 3D Printed Horrors yesterday. LINK. He covered things that nobody else has and helped me decide to go ahead and strip mine down to a kit again. I found both vertical extrusions were all cattywampus. Neither end on either extrusion had true 90 degree cuts. Right side was leaning forward and out while left side was leaning in and back! No wonder I couldn't get a straight print! ARGH! I have a nice miter sander and used it to sand the extrusions just until I had a perfect 90 degrees at each end. All extrusions now fit together like a glove. The X axis carriage was funky as well. I straightened it as well as I could but it still doesn't track as good as I'd like. I'll probably try to order a replacement. I did a few test prints last night after just a few stepper corrections and I'm much happier now. Even hole sizes are better. Not perfect but MUCH better. I think with a little more stepper tweaking and a new X axis carriage plate I'll be able to print coins for the U.S. Mint. LOL. ;)

With the holidays I won't be doing much more with this for a few days.

Happy holidays to all!

Joe
 

Turbojoe

Elite member
Now that I have my printer mechanically sound I'd like to now hone in on the stepper motor calibration. There are a bazillion mostly useless YouTube videos out there with mega annoying music tracks that were posted mainly to generate revenue and I've spent hours and hours watching most of them unfortunately. I have an OK idea of the calibration operation but need some truly helpful info to get X, Y and Z to play well together after adjustments. I'm getting ready to delete virtually everything and every link 3D printer setup related I've ever downloaded and start all over again with hopefully some good info now. I'm not high (today) and I fully believe I can at some point get this printer to print exactly the dimensions I expect it to.

I'm sick of useless YouTube videos. Hopefully someone has links to websites with GOOD info on the stepper calibration subject that a non engineer can find helpful.

Joe
 

Turbojoe

Elite member
After hours of time and yards of filament to print close but never close enough prints and many more hours wasted on useless YouTube videos I finally stumbled on the simple answer to my problems in an obscure Reddit post.

Joe
 

kilroy07

Legendary member
Awesome, glad to hear you didn't give up! (I got distracted with my wing and balsa builds..)

I always caution new 3D printer users that it's as much a hobby as anything else (maybe not a true "hobby" but it can take huge chunks of your free time as only a hobby can!) :LOL:

Curious to a few things you said, the fit/finish... was this a true Creality kit?... I got a CR-10 knock-off and it was just about unusable (so I'm converting it to linear rails!) but my true Ender-3 was actually pretty well made...

So what was the issue with the steppers, have you looked into upgrading to 9 degree steppers?... (yea, I know... that's a whole 'nother issue) ;)
 

LitterBug

Troll Spammer
My current beef with 3D printing is retraction that is not happening some times on this Model-V frame. This is causing stringing, which in turn causes a weak print since the strings should be part of the structure rather than in the middle of the print.... >sigh<

It's always something when printing. Every part and/or model has it's unique entertainment value to keep one's sanity in check. LOL

Cheers!
LitterBug
 

Turbojoe

Elite member
Curious to a few things you said, the fit/finish... was this a true Creality kit?... I got a CR-10 knock-off and it was just about unusable (so I'm converting it to linear rails!) but my true Ender-3 was actually pretty well made...

So what was the issue with the steppers, have you looked into upgrading to 9 degree steppers?... (yea, I know... that's a whole 'nother issue) ;)

It's a Sainsmart Ender 3 so yeah, I guess it's a clone. So far the poorly cut uprights have been the only real problem. Once I got them squared up it made a MAJOR improvement.

I still couldn't get vertical print size to change though no matter how I adjusted Z steps. A 3.0 mm request always gave 3.11 to 3.17 mm no matter what I did. It was driving me nuts. I saw on Reddit someone with similar issues. He made changes to the "horizontal expansion" in the shell section of Cura. I figured what the hell I'll give anything a try at this point. My first change was minor at -0.02 mm. Turns out that is just about perfect for me. Now the part thickness is at 3.03 mm and my 2, 3 and 4 mm holes are within .03 mm of where I need them in a 10x10x3 mm test plate that measures 10.01 on both X and Y axis. Just to make sure it wasn't a fluke I printed out a servo plate I designed for the Airtronics Q-Tee at 51x40 mm with 2 12x24.5 mm servo holes and 7 mm fuse side glue supports on the outer edges of the plate. Everything came out great with no more than .2 mm variation at that larger print size.

I've already designed and printed steerable nose gear, main gear mount and servo plate for the Willy Nillies Eaglet 250. As soon as I get the 2 kits I'll feel more confident that I can make whatever adjustments are needed once I have a kit in front of me to actually measure and only need to print the adjusted parts once!

I'm a much happier camper right now.

Joe
 

kilroy07

Legendary member
I've already designed and printed steerable nose gear, main gear mount and servo plate for the Willy Nillies Eaglet 250
I was SOoo close to getting the Eaglet... Can't wait to see how it turns out!

I gave up on Cura awhile ago... I do all ,y slicing with Simplify3D now (not cheap, but I saw a marked improvement in my prints just from shifting over...)
 

Turbojoe

Elite member
I know Cura is the most used slicer out there but I'm not 100% sold on it. One HUGE problem is it steals the com ports so you can't use Pronterface with Cura installed. Simplify3D is just way too expensive for me so that one's out.

Since I got everything straightened out on the printer I've been a printing fool. I reprinted all of the Eaglet 250 parts after re-designing to eliminate all the compensation I had figured into the latest .stl files. They now come out damn near perfect. As a test I pulled out one of my battery chargers to make a stand for it. A cheap HK charger and I designed and printed up an inclined stand for it. Even at the 132 mm width of the main frame and with multiple parts it all came out sized as needed and fits together perfect. I'm quite the happy camper now. I may just try my hand at 3D printing my own 250 size fuselage soon. ;)

Joe