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December 7, 2016

Printer Vibration Iso – Part 2 et al

Before I get into the meat of the topic, I’ve noticed something rather interesting with the Arduino IDE and the Marlin firmware, at least on a delta printer.

During my tests with the firmware I’ve found the RepRap Smart Controller (an LCD2004) is very unresponsive when I was using the button on the controller. The whole printer “worked” fine, but, it was obvious that something had changed.

I initially thought that one of my “mods” in the firmware had affected it. However after going over my notes I couldn’t find anything that should affect the response of the rotary knob.

Purely by accident I was making yet another change to the firmware, when, much to my surprise, the rotary knob was back to fully responsiveness again. Say what?

I had inadvertently run the 1.6.5 version of the IDE and compiled and uploaded the firmware. Ah ha! I quickly ran the 1.16.13 version, re-flashed the firmware, ah yes, dodgy again.

Couple more tests and I found any Arduino IDE after version 1.6.8 caused the rotary to be flaky. I have no idea why, if it’s something in the IDE that has changed, if one of my libraries isn’t happy, or what, but it warranted a post-it note on the printer to remind me…

Printer Vibration – correction…

After my initial tests with my db meter a few days back, there’s been something gnawing at the back of my brain. Trying disparately to get out. Apparently. See, the 82db just didn’t ruddy sound, skip the pun, right. In my recording studio I’m well versed with sound check levels and something was wrong.

Tonight the penny dropped. I was metering the printer again with some new feet I made and I was sitting at 54db. What? How the? And then, as I said, the penny dropped. So for you audio geeks, here’s the scoop.

When I measured the original sound level previously, I was standing 1 meter in front of the printer. Cause sound measurement levels are supposed to be 1 metre away from the source. Tonight I was standing about 45 degrees off the front, but still one metre away. After scratching my head for a second or two…bingo. It hit me.

Or rather it didn’t “hit” me. What didn’t? The air stream from the fan. On my printers the fan blows directly towards the front of the printer. All db meters have very sensitive microphones and what I was measuring was the air pressure from the fan that blows 8CFM. If I put my hand in front to block the air flow, of course the sound level dropped.

But from the side, yeah, no air stream. Room was 50db without the printer doing any print job, and 54db with printing.

Live and learn. Again.

Feet Version 1

Here’s a recap of the original concept feet. I threaded the center of the vertical 2020 beam with a 5mm tap, screwed the mount to the corners, added the cute dollar store balls.

IMG 1987

Within a couple of days I found a couple reasons why this wasn’t a terribly bright idea. The first is, the damn balls roll. When I whack the stuck off the print bed, the whole printer wants to move because the print is stuck there. I also found the when printing with any speed, there’s a lot of movement going on. No, not so much it’s going to roll off, but enough that I didn’t get any warm fuzzies.

Lastly, there was the quality of the balls themselves. We’re talking dollar store stuff. I had visions of one of the balls splitting in half and the printer looking like the leaning tower of Pisa. Or worse, on my floor. In pieces.

This, of course, lead to a rethink.

Feet Version 2

It sort of started with, gee, I wonder what the balls are made of. Out came the box knife and I halved one. High density foam rubber. And not a lot of air holes in it either.

As I stared at the half, there was a spark of, ingenuity? Okay, so I didn’t want to throw out the pieces..I designed a holder for them.

IMG 2010

I used the same 5mm screw location from the last test set, added some double sided tape in the holder and mounted one on the corner.

Feet Mount

True it does stick out somewhat but the center is directly under the corner and the print is using a 50% infill.

Foot In Action

Now if the ball splits or whatever, the most the printer will lean is about 15 degrees. Plus with the design the printer doesn’t roll around or shift it’s weight on faster print jobs.

Just for the heck of it, I thought I would add three more cups for a total of six.

Iso V2

Safe to say that once you have the corners done, adding more doesn’t do much. Perhaps makes it a touch more stable but not by any margin that I could measure.

The other printer I have, I stayed with the corner design only.

Iso v1

Of course this printer has more weight pressing down on the corners than the one with six support points but really, I don’t see any difference in the amount of noise being transferred into the cabinet below.

All I hear now is stepper motor noise.

Isolation Enclosure

One of the disturbing things I see is 3D printer owners building all manner of cabinet enclosures to assist in printing the tricky ABS, or trying to keep the noise from the steppers at a level where they can get some sleep at night.

Why is this disturbing? Pretty simple. Electronic components are designed to work within a specific temperature range. The majority of commercial components are designed to work from -30 – +70C.

The ATMega2560 CPU is designed to work -55 to +85C. With a heated bed, in an enclosure, warmed up to 80C+, the not so earth shattering news is the component is not going to last as long as if it was in the free air.

On the printers that are designed to be enclosed, there’s no doubt a cooling fan for the electronics and a vent out of the enclosure. However, these are brand name printers, not the knock off junk one finds on fleaBay, BangGone, or AliExpleatedDeleted…

Secondly, the RAMPS board has some MOSFET’s on it and while those handle heat quite well (depending on the MOSFET on the board), adding some 90-110C heat to it, you know, just to keep it warm, isn’t going bode well over time either. Plus if you have under gauge wire for the bed, a bad connection to the terminal block on the RAMPS board, yeah, not going to bode well. At all.

Food for thought any way.

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