Print dimensions off
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Just to clarify yes do 6 or 8 factor (might as well do
but change rod length manually (don't forget config_override.g) to adjust xy dimensions. Only two factors (directly) affect your objects z height, over extrusion or incorrect steps/mm. Use the calculated steps/mm for your titan but fine tune using a printed object (plenty on thingiverse) as the pinch wheel pressure and softness of filament affects the effective gearing.I totally agree that it should be motors, pulleys and belts that determines tower steps/mm but if you're extruding the right amount of filament and objects are always the same % too tall you need to change steps/mm. Incidentally a lot of people swear by 80.5 steps/mm with 1.8 motors, 20t pulleys and gt2 belts. But in your case you might (once extrusion is ruled out) need to lower yours.
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Duet Web Control
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Okay X and Y seem to be consistently +/- .05 and Z is 20.50-20.60 depending on how hard I push my calipers together. E steps /mm are what I'm supposed to change to shorten z?
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Lower E steps per mm will extrude slightly less filament and therefore its a test to see if you're over extruding. Reduce it by 1% and then print it again. You can do so from paneldue/web interface by reducing extrusion /extruder to 99.
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If this doesn't solve the problem or improve it at all try lowering your x y and z steps/mm by the % that the part is too tall, then autocalibrate again and print it.
If you want a more precise method try this object I designed. http://www.thingiverse.com/thing:1619976
Split the model in slic3r and print one cube at 15% infill and the other at 95%. The 15% one shouldn't have stringy infill and the 95% one should have tiny gaps between the infill lines after layer 6-7, theres detailed instructions. -
I would do a 6 or 8 factor Calibration and do a test print with L set to as close as you can measure the centre to centre of your Rod Pivot points.
Then do the Measurements.
Z is affected by Steps/mm and x and y by the rod length.
So as Dj says if after you do this you side are short then reduce the L value and try again.
Bare in mind tho that the Plastic does Shrink when it cools and different plastics do so at different rates so you have to decide what is important to you as you can allow for the Shrinkage rates in the Slicing software. (ie if you know the different shrink rates you can allow for it in the Slicer so you need to get it as close as possible taking shrinkage into account)
I Would not allow the Firmware to adjust the Rod Length for you as that is better done by Careful measurement if possible or by calibration as above.
Hope this makes some sense
Doug
What Slicer do you use that takes shrinkage into account? I use Slic3r and have never seen that setting.
Simplify 3D allows you to adjust the Horizontal Dimensions % for each individual type of filament or even by brand if you set up a process profile for it!
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You can also use the M579 command to scale the axes, see https://duet3d.com/wiki/G-code#M579:_Scale_Cartesian_axes. However, if your diagonal rod length or steps/mm is off, you are likely to find that when you print long straight lines, they come out slightly bent.
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With slicer I often factor around 0.7% dimension change for ABS.
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Hello,
I have a kossel xl with duetwifi board. If I print a square that has a square hole in it the outside dimensions are perfect but the internal square is undersize by .4mm. If I then print a round disc with a hole in it the outside and inside dimensions are undersize by .4mm. Can the M579 command be used to fix this issue?
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If I print a square that has a square hole in it the outside dimensions are perfect but the internal square is undersize by .4mm. If I then print a round disc with a hole in it the outside and inside dimensions are undersize by .4mm.
Maybe this can help you:
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I print everything with an extrusion multiplier of 90% which gives me the best dimensional accuracy and the best surface finish. No idea why it works but for me it does. My ageing Mendel prints everything slightly small compared to my newer CoreXY - same gcode files, same print settings, same filament and hot end end design. Again, no idea why. I recently discovered that with two parts which dovetail together for a sliding fit with negligible play, making them both in black worked well but making the male part in gold coloured PLA gave a loose sloppy fit. Changing the clearances so that printing the male part in gold PLA gave a nice smooth sliding fit, then printing the same male part in black PLA resulted in a too tight interference fit. Both filaments measured spot on at 1.75mm and of course, this was the same gcode file printed on the same machine with exactly the same settings, so yet again no idea why. I think that where dimensional accuracy is critical, it's just a matter of trial and error to get a perfect fit and what works on one machine, may not work on another.
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uvarovkv,
I can see your analogy but the path is surely controlled by the slicer which is not taking into account that this is a hole and the path needs to change.
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deckingman,
I totally agree with what your saying. But I am just trying to get my printer tuned in with one filament to start with and can then adapt from there.
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My twopence worth the issue with external and internal dimensions specially holes is that holes are often too small due to the fact that they are polygons not circles.
Ian that extrusion multiplier..I know we talked about it before regarding titan extruder steps/mm. But if you set your steps/mm 10% higher and used 100% extrusion multiplier you'd get the exact same result. All those numbers are all just a measure of how many revs of the drive gear are performed for x mm (or mm3) of filament requested.
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…...................Ian that extrusion multiplier..I know we talked about it before regarding titan extruder steps/mm. But if you set your steps/mm 10% higher and used 100% extrusion multiplier you'd get the exact same result. All those numbers are all just a measure of how many revs of the drive gear are performed for x mm (or mm3) of filament requested.
Yeh, I know. Two different ways to achieve the same result. I have the extrusion multiplier set in Slic3r under "Filament settings" so everything gets sliced using 0.9 extrusion multiplier and I don't have to think about it. It's just my personal preference to have config set to the "correct" value and then tweak it in the slicer. It's kind of like the Z offset that we've spoken about - I prefer to use a (negative) number in my G31 but you prefer to use an offset in your slicer. It's just personal preference and there is no right or wrong way to do it as long as it works. Cheers. Ian
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Fair enough, I have reverted to using the probe offset in firmware.
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Instead of starting a new thread with the almost the same subject, I hope it's OK to fill in this thread!?
I'm printing this delta calibration model: http://www.thingiverse.com/thing:745523
I have adjusted the diagonal rods so that I´m getting 50.99mm in Z (It should be 60mm), but both X&Y are off about 0,2-0,5mm.
Is there any way to adjust Y & X size separately?
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My understanding of delta kinematics is that there is not, since x and y movements are intrinsically linked to one another, unless its being caused by something mechanically off on one tower, that is okay on the other two, play in a joint, a slight twist etc…
How does adjusting the rods change the Z? Since Z is generated by moving all three tower carriages by x steps then as long as your steps/mm is correct, moving the nozzle to 60mm it should have exactly 60mm below it (+/- thickness of a piece of paper if you use that test to set nozzle gap).
X and Y scale is determined by your rod length setting in firmware. Longer rod setting means smaller objects and vice versa.
You can scale the object when you slice it but that's a pain in the a**.
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DjDemonD is correct. The Z height is determined by your steps/mm, and diagonal rod length affects the XY scaling. However, if you change diagonal rod length in an attempt to compensate for geometrical errors in your printer, then you will find that printed lines that should be straight will come out bent.
I suggest instead that you:
1. Correct geometrical errors as far as possible. See https://duet3d.com/wiki/Calibrating_a_delta_printer#Make_sure_your_build_is_accurate.
2. Print pairs of parallel straight lines from one edge of the bed to the other at different angles, each line half a bed diameter away from the centre at its closest point of approach. Then check that the lines are parallel. If they bow inwards or outwards, adjust the diagonal rod length and recalibrate the printer. Repeat until the lines are straight.
3. Use the M579 command https://duet3d.com/wiki/G-code#M579:_Scale_Cartesian_axes to correct any scaling errors.
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DjDemonD is correct. The Z height is determined by your steps/mm, and diagonal rod length affects the XY scaling. However, if you change diagonal rod length in an attempt to compensate for geometrical errors in your printer, then you will find that printed lines that should be straight will come out bent.
I suggest instead that you:
1. Correct geometrical errors as far as possible. See https://duet3d.com/wiki/Calibrating_a_delta_printer#Make_sure_your_build_is_accurate.
2. Print pairs of parallel straight lines from one edge of the bed to the other at different angles, each line half a bed diameter away from the centre at its closest point of approach. Then check that the lines are parallel. If they bow inwards or outwards, adjust the diagonal rod length and recalibrate the printer. Repeat until the lines are straight.
3. Use the M579 command https://duet3d.com/wiki/G-code#M579:_Scale_Cartesian_axes to correct any scaling errors.
While reading your section on building an assembling a precise Delta/Kossel/Rostock I was researching how to ensure everything is accurate.
I found replacements for my injection molded corners without me having to CNC mill my own (which I know everyone may not be able to do).
http://www.robotdigg.com/product/395/Metal-Corner-for-Kossel-of-2020-Profile(They also have corners for 2040 and 3030 as well as for nema 17 or nema 23)
I have MGN12 linear guide rail coming so there is less slop on each movement and already have the aluminum effector from robotdigg (rails are from robotdigg)
Do you have anywhere to get delta rods that are assembled so I do not mess them up? I hesitate using magnetic rod ends.
