3D printing

[Darth Geek]

I added vibration dampers to the stepper motors, flexible feet that the machine sits on, and tightened the belts a little. I'm making a bunch of the XYZ test blocks to see how jerk settings and acceleration effects things.
I'm also thinking about putting in TL Smoothers.

[MartyS (Gromit)]

I was always doing that kind of thing, making adjustments and doing mods, the darn Prusa has been so good it hasn't needed anything except a better part cooling fan shroud...

[Darth Geek]

Aaaaand that didn't do anything. 500 mm/s/s to 1500 mm/s/s acceleration and 5 mm/s to 10 mm/s jerk. Literally no noticeable difference in the 20 X 20 XYZ block.
The flat surface seems to be okay, no blobs or anything. It's still the edges being bulged. And the layers being not quite lined up at each point of change in the design features.

[MartyS (Gromit)]

I've never found acceleration to make much difference, but jerk settings usually do.

Since you made the numbers higher did you notice more vibration that can lead to more ghosting?  I thought you were trying to get rid of ghosting?  Lower numbers let the printer settle after an abrupt change in direction and reduce ghosting.  The value for jerk is how fast it accelerates out of sharp corners.

Could be that the stepper motor was sized for bowden and is under powered for driving the mass of a direct drive head, if that's the case the only option is to print slower (or get a stronger motor).

What do you mean by edges being bulged?  Is it over extruding?  Did you calibrate the new direct drive head?  Mark the filament with a piece of tape something like 100mm from the head, tell it to extrude 50 mm, then measure to see if it did move 50.

[Darth Geek]

This is the edge bulging issue:



The Print Speed is 80 mm/s, but I slowed the Wall speed to 25mm/s to help the outer skin look better.

[MartyS (Gromit)]

You'll have to experiment with the jerk and acceleration settings to stop the head from overshooting or over extruding on the corner.  Some printers combine the settings so you have to mess with both, some treat them independently.

If you set them higher and higher and the bulge gets worse, then it's overshooting the corner.  If you set them lower and lower and the bulge gets worse the head is pausing too long at the corner and over extruding.

Over extruding will make a bulge all around the corner, overshooting will make a P shape with the bulge only on one side of the corner.

No need to print a full cube for testing, a few millimeters high is all you need to see the results of each change.  Make a change, do a print, tape that square to a sheet of paper with the jerk and acceleration settings written on it and repeat with different settings, you should be able to zero in on the best setting after 4 or 5 tests. 

If nothing helps then it's a limitation of the hardware, belts might be cheap and stretching more than they should, motor is too weak and doesn't have the start/stop power needed, slight flex in the frame when the head does a fast 180, etc... 

Thinking about the motor reminds me that you should also check the tightness of the set screws on the pulleys, they are probably OK but even a tiny bit of play can cause issues like this.

[MartyS (Gromit)]

Been 3D printing lots of stuff for my mini-lathe.

Found files on Thingiverse for all the plastic gears plus larger versions.  Tried out the 100 tooth gear tonight and it works great, only problem is I can't put the cover back on with it on there.

I'll try the 90 tooth version and if the cover fits with one I'll try 2, that should give the same reduction as one 100.



The stock setup is: 20:80:20:80 for a reduction of 1:16
With that 100 tooth gear it was 20:80:20:100 giving 1:20
If 2 90s will fit that would be 20:90:20:90 giving 1:20.25

These are the same gears used for cutting threads, the lathe comes with a bunch of different sizes, so it's nice to know I can print new ones if one breaks, a set of metal gears costs over $100.  The reason I want to try larger gears is to slow down the feed rate to get nicer surface finish.

Also made a dial indicator holder for the tool post, this is the 3rd one I printed, downloaded one that was just a little too big for my post to grab it, then designed my own that didn't quite work, so redesigned it and this one works:



And this one also took a few attempts.  The way this compound feed works is a terrible design, the metal dial is what does the work of pushing the slide when you are moving in, way too much surface area and it binds up.  I made a brass bushing that does the work much better but didn't want to modify the original dial in case I switch to using ball bearings.  So I 3D printed a new dial.  First one I used sharpie in the grooves and that wasn't great.  So I made the groves a little deeper and filled them with epoxy, then used the lathe cut the dial down until the black groves had good edges.

[MartyS (Gromit)]

I printed two 90 tooth gears and one fits but not 2, one of the bolts that holds the slider for adjusting to different size gears rubs against the larger 90 tooth gear.  The cover fits on with the one 90 tooth gear so that's nice.

If I ever need a really slow feed rate I did find that a 100 and 90 will fit, just can't put the cover on.

[MartyS (Gromit)]

Well I thought I was done 3D printing stuff for the lathe but the size of the hand wheel was bugging me, way too big for this tiny lathe, so I designed a smaller one and it has a much better feel to it when moving the carriage:

[Darth Geek]

Just the last few weeks I have suddenly started having the worst trouble with really bad rippling (also called "ghosting" or "ringing"). I have made sure might my belts are at a good tightness, I even added belt tensioners to adjust them. I just replaced my X axis stepper motor and no change. I have the Y axis on order (for some reason the 42-40 dual shaft that the Ender 5 uses on the Y is almost impossible to find). I have checked my rollers and they are smooth and at a good tightness on the crossbars. I have vibration isolator feet on it. And this is an Ender 5, so the frame is nice and rigid.
The thing is, I am getting the rippling now with the SAME GCODE files that I was using before and did not get rippling, so I know that it is NOT in my slicer settings! But most of the suggestions I find when I search for it are all about those settings (which I'm already doing in my slicer settings anyway).
One other thing that started happening at the same time that I hadn't seen before was on long runs I get layer shift near the end. Again, my belts aren't the problem. But that layer shifting could be caused by the stepper motor controllers overheating and stalling for a little to cause the shift. Could the motherboard be going bad and that is causing my rippling too?

[MartyS (Gromit)]

Check for build up on the pulleys, if the groves on the stepper motor pulleys get filled with gunk they don't grip the belts as well as they should.

Double check the tightness of all fasteners, screws can come loose after many hours of printing, especially the screws on the stepper motor pulleys, but also check the frame screws to see if any of them may have come a little lose.

If you have been printing a lot belts do wear out, if you have checked everything else the ringing could be caused by worn out belts, a meter of belt isn't that expensive, I keep extra on hand.

As for the layer shift near the end of a long run, is this happening when the room is warmer due to the heat wave?  Most likely it is a temperature issue, you can put heat sinks on the stepper motors, or put a cheap PC fan blowing on the controller board.  I would not think the ringing would be related to temperature but if it started at the same time perhaps it could be.

[Darth Geek]

Check for build up on the pulleys, if the groves on the stepper motor pulleys get filled with gunk they don't grip the belts as well as they should.

Double check the tightness of all fasteners, screws can come loose after many hours of printing, especially the screws on the stepper motor pulleys, but also check the frame screws to see if any of them may have come a little lose.

If you have been printing a lot belts do wear out, if you have checked everything else the ringing could be caused by worn out belts, a meter of belt isn't that expensive, I keep extra on hand.

As for the layer shift near the end of a long run, is this happening when the room is warmer due to the heat wave?  Most likely it is a temperature issue, you can put heat sinks on the stepper motors, or put a cheap PC fan blowing on the controller board.  I would not think the ringing would be related to temperature but if it started at the same time perhaps it could be.

Thanks. There is a little build up in the grooves of the pulleys, so I will clean that off. I also got new Gates belts which are supposed to be better.

I want to replace the tiny motherboard cooling fan with a bigger one. I got a nice 92mm Noctua fan and modified my bottom plate to fit it. But now I'm having the issue that I don't seem to be getting power out of the wires for the fan. I cut the existing ones to remove the original fan. And I stripped away the ends so I could attach it to the new fan (with a Buck Converter to reduce the voltage from the printer's 24V to the 12V the Noctua Fan uses). Unfortunately I had the wires exposed while the machine was on and they must have touched because they made a spark at one point. Now when I turn the machine on and hook the wires to a voltmeter I don't get any reading. Is it possible I burned out that part of the motherboard?

[MartyS (Gromit)]

Unfortunately I had the wires exposed while the machine was on and they must have touched because they made a spark at one point. Now when I turn the machine on and hook the wires to a voltmeter I don't get any reading. Is it possible I burned out that part of the motherboard?

On my Prusa board there are fuses, they use the little plastic automotive type, if your board has them look for them, hopefully they put a fuse in for that fan.

If there is no fuse for the fan circuit you probably blew out a component on the board.  That's the hard way to learn not to leave stripped wires flopping around with the power on.

If the board still works for everything else you can get 24V directly off the power supply to run the fan.

[Darth Geek]

How long is it supposed to take to flash the firmware? I put the firmware.bin file on the SD card (removed other files) and turned the machine on with it in. It has been a blank screen for over ten minutes. I don't dare turn it off. Is it still trying to process? Will it hurt it if I turn it off?
I know the new board works because I turned it on and it was fine, it just thought the machine was an Ender 3 by default. And I made sure to switch all the connections one at a time to the new board so I got all the wires correct.

[MartyS (Gromit)]

I don't know about your board but just about all the electronics I've ever flashed the longest I've seen it take is probably about 3 minutes.

If it's been over 15 minutes it's either bricked or hopefully just stuck in a reboot cycle.  Pull the SD card and cycle the power, hope it comes back.  Did it ever give a message that it was doing an update, usually they put some kind of message on the display. 

Both of my printers don't allow flashing from SD, you have to connect a computer via USB to do it.