Wednesday, November 30, 2016

More Monoprice MP Select mods

I just found this site:

If you have an MP Select printer, you should go check it out.

I updated both my LCD and motion firmware from that site this evening, it has already fixed some bugs (the biggest one was that gcode contained in SD card subdirectories didn't print correctly).

It also adds PID Autotune, which was BADLY needed, especially if you have replaced your hotend with an E3D as I have.  Follow the directions on that link, it's very straightforward.  However, it still doesn't seem to be nearly as good as my old RepRap was. It still varies by as much as 4 degrees.  The RepRap would go to temp and stay there for hours without budging. More experimentation upcoming. I'm probably doing something wrong.

There are also a bunch of great mods and ideas on the site, including a clip to reset the Z endstop height if you want to add a glass printbed. I could have used that, I just mangled the switch to do the same thing. I was thinking about designing a clip like that but it's nice that it's already done.

They have Slic3r, Simplify and Cura profile packs for the printer, 

I've also printed this knob, which is WONDERFUL compared to the junky knob it shipped with.

I just finished installing this lower profile E3D adapter. The original one which is widely touted starting on the Hackaday review is OK but offsets the printhead significantly, losing about a centimeter of print volume in the Y direction.  This still has some offset, but much less.

Also this fan shroud, which uses a 40mm fan and provides part cooling as well.

Here's the hotend and fan shroud as they are now:

Pretty prints

The Monoprice MP Select can produce really nice prints if the slicer is set up well:

Saturday, November 26, 2016

Building the 8x8x8 LED cube from BangGood

I bought this LED cube, I've always wanted to put one together.  This one was a bit frustrating because there were NO instructions to speak of whatsoever.  In the end I made to errors - I had the polarity of the matrix reversed (I originally wired positive to the grid points and negative to the horizontal planes, and it wasn't working well at all.  Reverse of that is correct).

In the end it's a pretty cool toy for < $30.

Here's the link to the product on BangGood's site.

Here's the video I made of how to build it.

I also made this quick dumb little guide for properly spacing the planes before soldering in the wires to fix them in place:

Here's a link to the STL if you want to print one.  Or you can just hacksaw slots in a hunk of wood or plastic or something every 20mm, whichever.

Saturday, November 5, 2016

Updates to Monoprice MP Select Mini printer

A couple of months ago I bought the $200 Monoprice mini 3D printer.  I really like it.  It has some warts but in general it's nice, small, portable, and just does the job.

Things I wouldn't mind seeing improved:

  • Temp control isn't as good as it was in my PID tuned RepRap. They may be using bang-bang not PID.
  • Arm stability is just a little wobbly.
  • The Z axis endstop could really stand to be adjustable, for trying different print surfaces.
  • The hotend is fragile
The Z axis switch is just fixed in place. When I decided I wanted to put glass on top of the print surface, the surface couldn't be cranked down far enough so I had to bend the arm on the switch. I will try to come up with a better solution to this later.

The hotend works well at first, but as soon as I had the first trouble with it, it became very cranky and started causing a lot of trouble,  The 30mm fan failed which led to a bunch of jamming because I was too dense to notice the fan not running. Once the fan was replaced I still had issues, and the little springs like to go flying around the room when you disassemble it.

I had already ordered a new hotend to go with it. I decided to try out one of the $10 E3D all metal clones out of China.  When it came in, I was very impressed with the quality. I actually owned a legit E3D a while back, and I don't think I could really tell the difference.

In any case, I used the hotend adapter that Benchoff posted on Hackaday and Thingiverse.

It works very well, and I got a bag of 0.4 and 0.5mm nozzles to play with.

I have some PETG filament coming which prints at 235 degrees, so the all metal hotend 

Wednesday, August 31, 2016

Mini printer mods - printing on glass

After the first couple of prints, I wanted to get read for regular use, so I cut a piece of glass to use as the regular print surface. I have had little luck with printing on glass in the past but decided to give it another try.

The main problem that I had is that there isn't enough adjustment in the Mini to allow for a sheet of normal window glass on top of the print surface. I may come up with a more elegant solution later but for now I just bent the lever on the microswitch up to get the Z zero within adjustment range.

I hit another problem in that the preheat menu only allows you to go up to 60 degrees. You can adjust higher than that after the print starts, and the GCode can call for higher, but you can't preheat up to the 70 degrees you want for PLA on glass.

I am still working on the startup gcode for this printer, so I wasn't getting the glass quite hot enough. For now I used a bit of hair spray on the glass and it's printing fine.

I will probably put kapton on the back of the glass and flip it for ABS.

As you can see below, the glass is just held down with a couple of small bulldog clips. You can also see that I need to do some tuning - I thought I had the retraction set at 4 or 5 mm but it's only at 2, therefore the stringing. You need a lot of retraction with a bowden tube system.

Tuesday, August 30, 2016

New printer: Monoprice MP Select Mini

I recently decided to look at tiny printers for travel and to clear up some space in my workshop (I will keep the big printer but 95% of the time a much smaller printer will do the job).

I wound up ordering a Monoprice MP Select Mini. It is truly amazing what you can get for $200 these days.

Hackaday did a good review and teardown, here is a link to it. They did a spot on excellent review. I agree across the board. The 32 bit processor and display are great. The control dial is a bit fiddly, I may print some glue-on aids to rotation. The PID on the temp control is horrible. I'm going to see if it's possible to tune the PID manually if it still doesn't have auto-tune.

My printer came with two problems out of the box which were trivial for me but which would probably have greatly frustrated a newbie.  First, when I hit auto-home, it spiked the hotend into the bed. I hit the power switch, then used manual motion controls to retract the Z back up again.  I discovered that the connector for the Z axis endstop switch had fallen out.  This is actually visible without any disassembly. I was able to just push it back in place with a butter knife.

Second, the Z axis was level but far too low. I suspect that an impact during shipping, or perhaps final assembly, might have knocked the Z switch and the wire downwards. I screwed all four adjustment screws down 1.75 turns to reach a good zero height.

For me, this was a 5 minute trivial inconvenience. For a newbie, it would have been at the very least a call to tech support, and possibly a very frustrating reason to return the printer.

The minor issue is that the square spool holder on the side will not allow you to put on some of my spools that have a solid core. I had to bend down the retaining tab on the side a bit to allow them to go on.

Those things aside, I love this printer. I do not hesitate to recommend it, I will be using it as my primary printer instead of the CTC which will go on the shelf unless I need dual extrusion or a big print area.  If I were buying a big printer again at this point I would also definitely take a hard look at the larger Monoprice units, which Hackaday also gave great reviews of.

Friday, August 19, 2016

Laptop mainboard - ALMOST right

My last post was about a laptop mainboard that I dropped in, and that it only had one thing different - a different connector for the feature buttons.

Well, then I noticed that the touchpad buttons didn't work.  And it didn't think there was a battery plugged in.  And the LEDs up front (power, battery, wifi) weren't lighting.

I opened it up again, and found that there were no switches installed on the mainboard for the mouse. I surmise that it was for a slightly different model that had buttons in the touchpad (there is also a populated connector on this mainboard in the right place, which is probably for that purpose).  So I got the hot air out and removed the switches, and moved them. I also desoldered the LEDs from the old board and moved them (no mean feat - they are 0603 LEDs).  I plugged in enough to power up, and no luck. The LEDs didn't light, and the mouse buttons still didn't work.

I compared the boards and determined that the mouse button switch leads go through a couple of 0603 100 ohm resistors. One was still on the board, so I moved that one. The other one was probably lost when I swept the switch off with the hot air, so I put in a 330 ohm resistor which I have on hand. This worked.

The LEDs, probably a similar story because I noticed that it had LEDs already in place elsewhere on the board and those were working. I just drilled three holes in the top of the laptop to let the LEDs shine through and covered it with tape.

The battery - that was another story. Turns out the battery connector was about 3mm shorter on this board than the other one. I did manage to remove the connector from the old one and get it on the new one. This took over an hour. Lead-free solder is a pain in the ass when desoldering large connectors with through hole physical stakes.  On the old board, I ripped the via rivets out while desoldering, so I was super careful on the new board. I tried hot air on the old board first but it was just not working and I decided if I was going to have to use other means on the new board, best to practice on the old one first.

Anyway, that's all working now, the LEDs are shining through the lovely bodged holes drilled in the case, the battery is charging, and the mouse buttons work.

I would NOT have been successful at this stuff without the microscope that I bought last week. The parts are just too small for my eyes.  I think they're probably too small for anyone's eyes when you consider you need to examine the solder after your work is done. Maybe you could do it with a 10X loupe but I'm happy to have the microscope.