Dennis Brown: My printer tune up and alignment process and needed upgrades - psmay/mpmd-notes GitHub Wiki

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The original version of this came from https://www.facebook.com/groups/mpminideltaowners/permalink/2058169440865198/, written by Dennis Brown, as it was 2021-03-30. Refer to that post for updated information and comments. Some reformatting has been applied (its correctness is not guaranteed).

My [Dennis Brown's] printer tune up and alignment process and needed upgrades.

This post includes the following:

  1. A list of essential upgrades for the MPMD printer with links.

  2. Steps to align the printer for the best operation with links to more detailed instructions or information.

The post is primarily an index to my other posts. However, it will also contain pointers to related good posts by others or the Wiki.

This post will get edited often.

I know there is a lot of stuff here, but I had to do something in all these areas to get my printer up to snuff. I am still doing a few tweaks. It is running pretty awesome right now after doing something in each of these areas.

NOTE: All of these instructions are specific to the Motion Controller FW versions 45 & $44 and below, which is the version running on my machine.

  • V43 & V44: The latest shipping machines have a 16 micro-step stepper motor driver hardware upgrade. I will note differences in the instructions as they become known to me.
  • V45: Some new machines ship with version 45. These have 8 micro-steps and should use the same instructions as V41 unless noted otherwise.

A) Essential new printer hardware/Settings improvements (any order):

1

Update the step/mm for the 3 axis. The steps/mm for the 3 axis are currently set wrong in the factory defaults. Once you fix this, your optimal Z layer heights will be in multiples of 0.0175mm with 0.28, 0.21, 0.14, 0.07mm being the best.

<=V41, V45 with 8 micro-step controller, do this:

M92 X57.14 Y57.14 Z57.14
M500

***V43 & V44 with 16 micro-step controller:

M92 X114.28 Y114.28 Z114.28
M500

The X,Y axis movements are not accurate with factory settings. The Flatness of the X,Y motions are also not accurate with the factory settings.

To fix this, update the Diagonal Rod Length and Delta Radius to get it closer. It will be fine tuned later:

M665 L123.00 R63.50
M500

***V41 to V45: Because some of these settings do not survive a power cycle, you can make up a special .gcode file that you can "print" after every power cycle of your printer, or you can put them into the startup gcode script in your slicer:

M92 X57.14 Y57.14 Z57.14 ; correct Z accuracy -- different if not 14T pulley
M665 L123.00 R63.50 ; correct X,Y accuracy and Z flatness

Special note: The M665 L and R values interact as far a flatness and X,Y calibration accuracy. The values above are what works on my machine, but will need to be calibrated for each machine in a later step. Here is a recent post where I discuss the issues that affect bed leveling:

2

Replace 3 bottom feet with taller, noise dampening ones. Can be done out of order, if you need to order them online. The point is to get better airflow to the electronics so they do not overheat.

3

Replace the print surface with a more durable PEI surface (some prefer other surface treatments). Best to do this now before the final alignments, since the factory bed gets destroyed pretty quickly. I recommend a 0.5mm PEI sheet because it is tough and hard to destroy, but the surface is soft enough not to beat up the nozzle tip if you crash into it (like every time it self levels). It also sticks well at moderate temps, but releases well when cold with many filament types. I have placed it directly on the aluminum plate and I have also placed it on a round borosilicate glass plate that is placed onto the bare aluminum bed (with a silicone thermal sheet between them). If you proceed with alignments first, then recheck them after you replace the bed surface.

4

Attach printer power supply to a power switch of some sort. Do not plug and unplug the 12VDC power directly at the printer with the power on except in an emergency. Otherwise the connector will degrade over time and may become intermittent.

5

Get a second (or third) microSD card. The one included has not been reliable for many users (though mine has been fine). You will need a good card for printing from card or upgrading the FW. Most higher speed and capacity cards do not work in this printer. The card that has worked perfectly for me and others is the one recommended on the Wiki.

6

Tune up the PID values for the hot end. The factory settings did not work on my machine.

Caution: The PID auto tune on my machine gave very poor results and others reported the same.

The numbers that work on my machine and seem to work on a number of machines:

M301 P45.00 I0.07 D1000 ; Hot end settings

***M304 P100 I0 D0 ; Bed heater settings lag only This is only partially tested on my machine and may require some other considerations for preheat (especially with a glass bed) that I am still exploring.

[FIXME: Part of the above looks like a typo; it's not clear where the line break was intended to go]

This is only partially tested on my machine and may require some other considerations for preheat (especially with a glass bed) that I am still exploring.

This would have to be checked or retuned after replacing parts on the hot end.

B) Printer settings for your slicer (do before printing anything other than the cat)

1

Set up printer hardware settings in slicer.

Cura 4.0 is now available for free. Might as well get the latest versions rather than the old version that is included on the original SD.

Brian Kurtz created some good Cura settups and beginner instructions. It will save you a lot of headaches to take advantage of his guide: bit.ly/MPMD101

Other less popular free slicers are also available.

Some prefer to pay for a Simplify 3D license.

2

Make custom startup gcode sequence for the slicer.

Use G29 P2 C0 Z0.5 temporarily for the G29 auto bed level line. The Z parameter may have to be adjusted by a small amount to get a good first layer to stick.

NOTE: After making the upgraded bed hold down clips in the next section you will be using G29 P6 or G29 P5 for the best first layer results.

C) Essential first time tune up process (MUST be done in order):

1

Set the belt tensions.

Belt tensions should all be the same and not too tight or loose. I describe a method to tune them to 110Hz by ear or phone tuner app in the following post:

2

Print out replacement bed hold down clips. These completely replace the factory ones. The rest of the bed alignments will not be stable without these improved clips. These parts don't actually touch the hot bed, so they can be made from any stable filament material. They could even be fabricated. The hardware bits will cost about $6 from the suppliers in the post:

Instruction video for removing and replacing the factory bed hold down clips:

Note: The binder clip adjustments for height should be made with the bed heated to your normal printing temperature, because the bed switches shift a little with bed temperature. Here is the post that discuses the need for this:

3

For the ultimate in bed alignment and dimensional accuracy, take the next step and replace the lower bed switches with floating top side bed switches that also allow screw adjustments to square the bed to the vertical rods. Here is the post that tells you how to do this:

4

Find a delta R and L values that will calibrate the X,Y axis. You can try the values that worked for my machine as a starting point:

M665 L123 R63.5

Tape a piece of paper to the bed (I used a 4.5x4.5 inch square). Place a piece of carbon paper loosely over the paper and send this to the printer (or print a file):

M665 L123
M665 R63.5 ; or whatever new value you are trying
G28
G29 P5
G28

Measure the X, Y axis for 100mm length. Adjust the R parameter (It will increase about 1mm per 1mm increase). Test and repeat until you have 100mm. You should be able to get it within about 0.1mm over both axis.

IMPORTANT: Write down the numbers you get for L and R parameters. They will be needed as the starting point for future calibrations.

The following post explains what is happening and has pictures:

5

Find delta R and L values that flatten the bed without messing with the X,Y calibration from step 4, and correct the home switches. It consists of the following two steps that are done together using a spreadsheet:

A) Flatten the bed using G29 P5 and update it with M665 Lxxx.xx Rxx.xx, where new R = R + change and new L = L + change*1.5

B) Equalize the home sensors using G29 P5 and update it with M666.

The home sensors can be adjusted by physically moving them, but it is very hard to get them really close. It is a good idea to have them physically adjusted to within about 0.5mm if you are able though.

Both of these steps are done at the same time using a spreadsheet.

This step alignment process is now in a separate post:

***V41 to V45 CAUTION: The delta radius value is not being restored after a power cycle. The value is saved in EEPROM, but is being ignored by the FW unless the M665 Rxx.xx command is input again after the power up. Here is the detailed writeup:

https://www.facebook.com/groups/mpminideltaowners/permalink/2058169440865198/?comment_id=2071582009523941 Dennis Brown: Bug in stock firmware causes saved M665 R not to be used

6

Print out 3 lower side shields to keep trash out of belts. There are several now on Thingiverse. Here is one:

D) First time and periodic tune up (any order).

1

Adjust the extruder steps/mm. You may need to adjust this number for each new roll of filament. If you change filaments back and forth, label each roll with the steps/mm number so it can be reset each time you use it.

2

Oil all rails and universal ball joints. I use Super Lube Multi Purpose Synthetic Oil with PTFE. I have the pen oiler version that I refill with the 4 oz size.

I put a drop on each rail above each linear bearing when the hot end is near the build plate. I also put a drop on each of the 12 ball joints on the ends of the 6 arms.

E) Optional things that require opening up the printer:

1

Add cardboard to block fan cooling the heat bed.

Or possibly print this which can be installed from the top:

EDIT: I no longer recommend putting anything in from the top side, as the lip to hold it in place may interfere with the bed heater when all the bed switches are pressed down. This will adversely affect the bed leveling.

2

Slow down lower cooling fan speed to reduce noise.

3

Move the connectors to make the Y axis face the front. If you do this, you need to redo the calibrations, because the firmware settings and hardware configuration no longer match. Do it first if you want it (highly recommended). However, if a future MP firmware upgrade fixes this, it will have to be undone in the hardware.

F) Make sure to refer to the Wiki for additional advice: