How do I increase accuracy with prusa i3v help requested..

I have a makerfarm prusa i3v that I love. I would like to improve the accuracy of the prints. What I mean is, I have tried to print some bolts and nuts from items I have gotten on Thingyverse. I can't get a threaded bolt and nut to screw together as it should (this is just ONE example of what I mean) . I have the hexagon 3mm hot end. I have the bed dead level and have slowed the feed rate to as low as 20%. I am using PLA.

Are there any procedures of ways to increase the accuracy of these fun machines. Do I need to change the hot end? if so, to what? Maybe the printer is already doing the best it can???
I don't know but I am hoping you can lead me to documentation where I can learn how to get better prints.

I have googled trying to find info on it but have not had much luck.

Thank you

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Thank you
Bill

You may have to be a little more specific as to what you are getting to get a reasonable response to this question. Including pictures of the prints may help. At the very least a link to the model you are having an issue with (some of the models may be at fault, if the tolerances are not reasonable)

Quality is a result of
Printer build quality - minimal backlash, smooth movement...
Calibration of axis - easy
Bed levelling
Calibration of extruder - harder as when you change filament you should redo this calibration.
Settings in slicing software
Speed of print
Polymer quality - consistent diameter
Temperature
Environment
...

Most of all observation and analysis of what has happened.

Its a long and iterative process.

Look at other peoples printers see how theyve done it.
Read through old posts on this forum and see how other people have improved there prints.
Ive learnt a lot from other peoples problem prints just by reading through old posts.

Look at each area of the printer seperately and do some research.
Electronics, x-axis, y-axis, z-axis, frame, extruder and so on.
Make small changes one at a time and test them with some of the numerous calibration and torture test prints.
You will also be fighting wear and tear so keep up with the maintenance. Checking and greasing bearings and making sure everything stays tight is part of the process. Its no good making improvements that are going to be canceled out by poor maintenance.

One of my improvements was to fit a hexagon all metal. So dont ditch yours its a very capable hot end.
So i could print more materials but also so i could swap out the nozzles for different sizes.
Some prints work better with a 0.5mm nozzle some better with a 0.3mm nozzle.

Another was to make the print bed more ridged. I replaced the old wooden bed with a sheet of aluminium and got rid of the springs holding the heated bed.
It made a small improvement to the printer. I also discovered i had a bearing on the way out.

I printed a better extruder and mounted the hot end more securely. Another small improvement to print quality.

I fitted better quality bearings.

And on and on, little by little till my prusa i2 as as good if not better than some commercially built printers.

You wont find something that immediately improves your printer but you can make small changes here and there that add up to an overall improvement.
You will also have a very good knowledge of your printer and be able to tune the slicer settings to work best with your printer.
So lots of research ahead for you.

Edited 1 time(s). Last edit at 05/02/2015 06:04AM by gordonendersby.

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Gordon
Currently have a tweaked mendel prusa i2
About to build a P3Steel.
[scratchpad.thisandthose.org]

Printer for hire.
[www.3dhubs.com]

Member of South London Makerspace:
[southlondonmakerspace.org]

Can I ask if Slicing software also make a difference. I am using Slic3r and are getting good results. Can not print fine thingies at this stage but are happy.
Would just like to know about slicing software.

Riaan

Im getting good results with cura with my small fine prints.
It seems to be a bit easier to use than some other slicers from what ive read on here.
To be honest ive been a bit lazy after trying cura as my first slicer i havnt botheted to try much else as so far its sliced everything ive thrown at it.
But i feel i should try others at some point.

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Gordon
Currently have a tweaked mendel prusa i2
About to build a P3Steel.
[scratchpad.thisandthose.org]

Printer for hire.
[www.3dhubs.com]

Member of South London Makerspace:
[southlondonmakerspace.org]

Gordon....um....WOW!
Are any of us going to live long enough?
Ahh...what the hell, it's the journey ..right?

A tweaking we will go!!

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Thank you
Bill

Accuracy on a 0.3 head is +/- 0.15 mm, unless you are able to extrude reliably at a value less than that.

Most standard I3's are at 80/80/4000 with X/Y stepping at .0125 mm/step and Z stepping at 0.00025 mm/step.

Unless you can reliably have an extrusion process that results in a less than 0.3 mm print out, that is the limit - 0.3mm.

Machine accuracy is not to worry about since the machine can step 24 times more precise than the printhead. Machine accuracy can be improved by making sure the bearings are all properly lubricated and not running dry, belts are tignt unless you have three axes of leadscrews and anti-backlash parts. If the steppers are underpowered or the belts sloppy, this can lead to slop. Plus, the more mass on the printhead leads to its own form of accuracy errors - the more mass, the more mistakes.

As mentioned before, every RepRap has its own personality and coaxing the max out it is the trip worth taking but with the realization that the machine is not zero flawed in any form at all. The idea of using the printed screw would be a good test of your machine and to get the best out of it.

I have discovered that I have a LOT to learn!!!
So...how do you eat an elephant?? One bite at a time!

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Thank you
Bill