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Archive for November, 2016

27
Nov

Printer Vibration Isolation

Honestly I have no idea how I get started on these projects somedays. I suspect it’s like a an idea or concept that’s been trapped in the dark cobwebbed corners of my mind and suddenly, they burst to the forefront. Or something like that.

As a guy with not just one printer, but two, Kossels, when both of them get going, the radio in the shop, which isn’t exactly top quality in its own realm, loses out to them.

It’s been a sort of quest to find a way to get them to be a little quieter. A few months back I had a Turnigy on loan and it actually made my Kossels sound quiet. But it’s gone now and I hear the drone of my own printers.

Today I’d had enough and it was time to do something.

In the past I’d try any number of things and in the process I’d learn a few things. The first thing is if you put a printer on top of a cabinet or table, whatever is under it will instantly be transposed into a speaker. Depending on the frequency where everything meshes, and trust me there will be some resonant frequency, it’ll be a mid-range drone, or a sub-woofer growl.

My printers sit on top of a 6ft x 30″ by 42″H cabinet as shown. The shelves aren’t empty and this is a good thing.

IMG 1985

I also tested a printer sitting on top of a wooden table, one that is 2″ solid oak top, 2 1/2″ square legs and solidly built. The drone coming from under the table area was wicked and the legs transmitted the vibration downstairs to the main floor through the floor/ceiling. Yep, easy to tell when the printer was finished its print job if you were downstairs.

I picked up some hardwood floor sliders, rubber on one side, fuzzy backing on the floor side.

Floor Things

They work fairly well, certainly better than setting the printer frame directly on top of a cabinet or table top.

Still I wondered if more couldn’t be done. I set about sleuthing and found all manner of things. From a MagLev setup, that apparently would wander on its own if you didn’t have all the legs absolutely level. Which made sense, sort of like mercury finding the lowest point.

To printed spring feet and even springs inside of holders. They were billed as vibration dampers but really, they just cut down the vibration from transmitting to whatever the printer was sitting on. If the printer shook to start with, it shook when all was said and done.

In a lot of ways, it reminded me of my recording studio. Where the monitors tend to reflect down into the shelf or cabinet they perch on top of. If it was concrete, no vibration at all. But that’s kind of heavy and unruly to deal with…

Just for a test, I lifted one of the printers while it was printing to see what isolating it might sound like. Wow. From the usual drone to little stepper motor noises.

I put it back down on my cabinet and grabbed my DB meter.

IMG 1986

The lowest reading I could get was 83db @ 1 metre. Moving the meter around I could get 85+db though.

I was thinking about mounting the printer on rubber pneumatic bladders like we used to have at work when I happened across a Thingiverse item. A very simple design, used dollar store balls about the size of a golf ball. I modified the mounts slightly and built my own.

IMG 1989

Those are somewhat soft squishy balls, worth all of $1.25. And wowzers, do they work.

All I hear now is the steppers. No more drone coming from the printer/cabinet/table. Because the balls are bouncy, I found the whole printer does move a little more, so I don’t know at this point if that’s a good or bad point.

It could be a good thing since it’s absorbing some of the energy of the printer as it tosses the hot end around. Most deltas tend to have vertical energy as opposed to the Cartesian’s X/Y axis energy.

Out with the DB meter again, doesn’t matter where I measured from at 1 metre, the highest I can get it is 81db. As far as sound goes, 2 or more db is a significant change. A 3db change is often perceived by the ear as twice the volume, because the ear is logarithmic not linear.

There is enough weight on the balls that there is no way it’ll “roll” off, perhaps even different kinds of balls would perform differently as well. No idea at this point. If these “high ticket” items start to sag, well, another $1.25 and all would be well again…

I also saw someone use tennis balls in the same concept. I also have those but the little toy balls seem to work just great so that’s what I am going to test with for the meantime.

So there you go. What to know what your printer would sound like if you did the same thing? Lift it up whilst it’s printing. If you like that, print the mounts and isolate it.

Trendy….

17
Nov

Delta 3D Printers – Mirth, Myths and Madness

3D printing is not new, it’s been around in some form or other since 1989 or so. What is new is the introduction of 3D printing for the hobbyist, we poor unsuspecting souls. This has been gaining momentum since 2011.

A quick search of the net will result in the fact that there are over 1,000 different 3D printers available today and a small percentage of those will be delta style printers. That small percentage is the basis for this blog entry. Dated, today. Stardate whatever…to go where no man has gone…oh wait, we have gone there.

Delta’s owe their heritage to Johann the person who provided the jumping off point, not to be taken literally, for the delta’s we have today. His first prototype was the Rostock, followed by the more refined Kossel.

While it seems like age ago now, a mere short 18 months ago what I knew about 3D printing could be written on your fingernail, in large type and the nail would still be plainly visible. I suffered from D.A.A.P at the time. What’s DAAP? Dumb As A Post. To put it into perspective.

When I started I understood there was some hardware and software to make the thing work. Software I assumed would be fairly easy because I’ve been writing software since 1979. That was a bit of a mistake looking back, but at least I had the background to figure things out.

The hardware, that looked amazingly easy, turned out to be not quite as straight forward as I assumed. Thus I decided I’d better have a good backup plan before I “built” any type of printer.

As it happened, David, one of the members of Fraser Valley Makerspace had cobbled together some extrusion, electronic bits and mechanical pieces, and made them available through the Makerspace as a Kossel kit. He had a working one, so…I decided it must work and bought one.

The Madness

There are seemingly two kids of people who want 3D printers.

The first are those who want to use it like a toaster. Take it home, plug it in, briefly read enough of whatever documentation there is to make toast and use it. Of course there’ll be some burnt bread, but there’s a better chance of it working at the on set, the learning curve will be mainly filaments and software.

My first piece of advice, if you’re this first type, buy a Cartesian printer. Brand name. Make friends with other people who have them, even better if they are local to you. Check out any local maker spaces, they make great resources. Something eventually will not make sense and/or break, you need a backup plan to keep the toaster toasting.

If you must build a kit, find someone who has built one that can help you build it. As a friend of mine put it, two heads are better than none.

The second types are the tinkerers. My ilk. Folks who love to build stuff, take it apart, tweak it, make it work better, change it, redesign it, use it and educate themselves to no end on it. Whatever it might be. There is as much joy in building as there is using for me and my ilk.

My logic at the time was that if I got stuck at some point in the build, I needed a parachute to help me over the rough areas and that would be where the Makerspace came in.

I had zero clue at the time I’d be dangling off that rip cord for more than a month with the ground rushing up at Mach 3.

I owe my sanity in my initial build to one of the FVM members, Rob. While he’d hadn’t built one of the kits himself, he did own a Ditto 3D printer and had single handedly got the mini-Kossel working at the space. Thus when I got stuck or didn’t get something, Rob to the rescue. A lot. He become, unbeknownst to him, Rob Rip Cord.

Even with a well equipped workbench, micrometers, scopes, power supplies but I have to say that I found I needed a metric tap and die set, metric drill bits, metric hex wrenches, metric hex screw drivers. I did a lot of shopping on fleaBay.

Plus my kit didn’t include any preformed wiring harness, no Dupont ends already in place, no power supply, or power supply wiring, thus for a fair chunk, I was on my own. However, having built circuits since I was 13, it didn’t really present much of a challenge in many respects.

There was a manual that I downloaded. It was supposed to be a guide on how to build the Kossel. Pretty evident from the start that the downloaded manual was for a different printer. Everything from the nuts and bolts to the extrusions were different. Sort of like building a Chevy with a Honda manual.

While I thought this lack of instructions must be unique, in hind sight I have now found scads of printers in kit form that clearly state, “If you don’t know how to assemble one of these, don’t buy this because we offer no manual or limited technical support”. Of course the price of the kit reflects this but still…not what a first time builder wants to start with. Me? I suffered DAAP, I was undaunted.

I finally reached the frustration point where I was either going to toss it out, or find the humour in it. Fortunately I found the humour.

IMG 0119

And while I’d like to think that I know what I am doing when it comes to building things, yeah, not so much for a 3D printer. Mostly due to the fact I didn’t know how the thing worked in the first place. DAAP.

I did everything backwards, wrong, or just dumbly. Heavy on the dumb. Hey I even lost some of the ball bearings out of the linear rails because I didn’t know they just slid off the rail…oh yeah. A comedy of errors abounded.

Yet, I still remember the first print…and no, it’s not supposed to be a lace doily cube. It’s what you get when you don’t have the foggiest notion of what you’re doing but you do it any way.

At this point, I wasn’t believing in miracles, I was relying on them.

IMG 0188

So I churned out a few of these stringy things, and they might have made good scouring pads for pots and pans, but something was amiss and I didn’t know what it was.

The Myths

And of course like every desperate individual I turned to the internet for help.

I was still suffering from DAAP I should add.

Using the net without knowing much is like using Dr. Google as your personal physician. There are thousands of DAAP sufferers like myself whose opinion and help is about as useful as a milk bucket under a bull.

Thus it was finally through the Makerspace gurus that I learned something new. A thing called “bed levelling”. My prints didn’t adhere to anything because, well, my basic point of reference didn’t exist. At least in this world.

My Kossel kit had an auto level probe, but for the Marlin firmware version I had, it seemed like every time I levelled, just before the print started the firmware tossed all the bed info it just collected and proceeded to print yet another scouring pad. Handy. Not. Auto level working? Not.

After learning many tweaked the firmware to adjust for the bed level I decided against that avenue. My logic was that if anything happened to the firmware I’d be doing it again, i.e. bugs in the levelling routines or whatever, well, yeah.

I decided to do bed level via mechanical style.

When I inquired how anyone levelled their beds manually, I was greeted with tales of woe, daring do, silicon snake oil and just plain dumb luck. I had copious amounts of dumb, just seemed to lack the luck.

The tragedy was that you loosened the top end stops with the micro switches on them and moved them up or down less than a cats whisker and hoped you got it right. For all three towers. With a flat blade screw driver. 1/8″ thick. Like that old saw, “Measure it with a micrometer, mark a line with chalk, cut it with an axe.”

I looked at the problem, pulled out a drill bit and did my first mod, on the 7th day. The ‘x’ marked the spot, put in an M3 x 6 bolt, the head triggered the end stop switch.

IMG 0199

What used to take days of fiddling manually to get right, took all of 30 minutes, 3 minutes to set the scripts in Pronterface. The only firmware tweak required was if the center of the bed was concave or convex. You had to change one of the rod lengths and re-level. Again, do it a couple of times and you can do it in your sleep.

For the X/Y dimension size, print a cube, measure it, calculate how much too big or too small it is, change a number in the firmware, level the bed if needed, reprint, check. Having built a number of Kossels for others, worst case from power on was out .21mm, best case build was out .06mm. You need that kind of accuracy to print a.. ah… Pokemon. Or something.

Eventually the FVM kit would be upgraded to include the screw carriage adjusters and better belt grips. Huge progress.

However the myth still exists today that delta printers are next to impossible to level, or will take days to do. So you must have auto level.

The real truth is, if you understand (or take the time to understand) how to do it, you’ll find you can manually level the bed, exactly, once. And unless you change the hot end, diagonal rods, effector or something that will change a dimension in the build area, you don’t level it again. Period.

I printed over 900 hours on my first Kossel before I changed the nozzle and did a re-level. In 15 minutes. Big whoop.

The fact is all 3D printers come with their own little bag of issues. Be it the slicer, firmware or how you communicate with the printer. Pros and cons. Plan on doing a lot of research and look for actual A/B print examples not opinions in a forum.

Lastly it helps, especially if you build a kit, to be an information sponge. Obtaining little bits of info from others with the SAME kind of printer as you and then TESTING that bit of info to see how it fairs on your printer will enable you to produce better prints.

Even after logging over 2,000 hrs on my first printer, I am still learning and testing what I can do to turn out better quality work.

The Mirth

You’d think that just having a printer that works would be joy enough. Truly it is very satisfying, but I’m going to step back a moment here and think out loud as to WHY my Kossel kit was more than I’d even hoped for.

LongJaw

For the two FVM kits I built for myself, my thanks goes to the FVM’er, David who, either by shear good luck or design managed to cherry pick most of the best parts for a Kossel build.

The one shallow item in the kit was the full graphic display (12864). As a software programmer I know how CPU intensive just updating these displays can be. I think I had mine on the Kossel for about 3 days before I tossed it in the dumpster (along side the auto level probe setup) and replaced it with a Smart LCD 2004 controller.

The rest of the kit, stellar. Just stellar.

The first is the linear rails. These are premium items that will give hundreds if not thousands of printing hours. Nowadays you see what I call the cheapskate bearings like the Rostock used for the carriages. They are big, burly, have mass, and will not wear well over the long term.

Second is the carriage pieces that I had a hand in modifying. The current ones hold the belts so much better and have the adjustment screws.

Third is the massive stepper motors in the kit. These are 1.68A steppers, probably overkill to the nth degree compared to the whimpy ones I see now, but they run great and cool.

The 2020 open beam extrusions do a good job of keeping the frame rigid, even when when printing up to the 210mm height on mine.

Then the stepper drivers. Out went the old A4988’s and in came the DRV8825’s. The 8825’s can deliver more current and/or finer stepping if you need it. Nice to have that additional overhead.

Heat bed. Many printers still don’t offer or come with a heated bed. My Kossels have a 220mm heated bed, large enough to print everything I’ve needed so far.

Top drawer extruder. Three redesigns later, the current one is the best design I’ve seen and I’d select it over any of the metal ones I’ve seen.

So…thanks FVM, David and Rob, from Rocky and Bullwinkle (and me of course)…

Twins Printing

9
Nov

Black is BAACCKKK…MG Chemicals

In my ever expanding quest to try out new filaments, I’ve always found that if you want to see how any filament performs, at the worst, just try out a roll of anything they make. In black. Seriously.

I’ve read that black filament is the toughest to print because of the dyes go into the production. Or magic. Yeah, one of those for sure.

Regardless of which of my delta printers I use, black has always been a bit of a duck shoot when it comes to getting good quality. Any other colour, no issues. Thus, must be magic. Yep.

As I sat staring at the two brand new unopened black spools of filament on my workbench I was undecided which I should try first.

The first was PLA, the new “improved” brand from MG Chemicals.

IMG 1911

The second, PETG. Truthfully PETG is my compromise to avoid printing with ABS (which gives me royal headaches) but it is so darn stringy and unpredictable that I haven’t printed with it much. Some would call that being a smart coward.

IMG 1912

Of course, I used common sense and did one at a time. And pigs can fly. Forget the common sense thing… I loaded up one of my deltas with PLA and the other with PETG. On the PLA I had to print out some tank treads for a robot I’m building so, 15 treads at a time. In black.

The treads are from Thingiverse Caterpillar Tracks. Although labeled as a work in progress, I’m doing it any way. Although I’d really like to build a fairly large Wall-E…maybe in time.

IMG 1903

My settings, 0.3 layer height, 50C bed covered in Elmers glue stick, 208C for the first layer, 200C after that. I’ve made 60 treads so far and they have come out absolutely perfect. No strings, no separation, just way better than I expected.

On the other printer, I decided to make something to hold my SD cards and flash drives. With PETG no less. Again, merely a design I found on Thingiverse called Moby_Stick

IMG 1910

My settings, 0.3 layer height, 50C bed covered in Elmers glue stick, 224C for the first layer, 222C after that. Used Slic3r’s built in support for the whale tail. Not the default supports but “rectilinear grid”, which I have found out is far better than the default support patterns.

On the whale the supports literally fell off when I chipped it off the heated bed. You got that right, I had to use a metal spatula to get it off the bed.

I’ve never had any issues with adhesion with Elmers and a 50C heated bed. I’ve read many a horror story from others about getting PLA or PETG to stick to the bed, heated or otherwise. With every solution from 70-100C heated bed to hair spray on painters tape, to Kapton tape. Me? Borosilicate glass, heated bed, 50C, Elmer’s stick.

Perhaps with a delta because the bed doesn’t move the glue stick approach works fine. But I’ve done the same with the standard Cartesian printer I had here and it stuck just as well. Thus the problem must lie elsewhere.

After the prints, I measured the diameter of the filaments. In hindsight it should have been done first but, well, in my excitement I kind of missed doing it. None the less, both the PLA and PETG measured out 1.75 on my micrometer.

Last year I used a number of different MG Chemical PLA filaments, which I will call “old stock” now. While colours like their gold or white were superb, some of the others, not so much. But this year, things are not the same old.

MG Chemicals has changed their products on Amazon. The new stock has cardboard sides and is labeled “Improved”. They aren’t kidding. I’ve noticed a few complaints about the size of the center hub not fitting some spool holders. Since I use spool rollers, spool center is a non-issue.

No idea what kitchen they are using to create this new improved brand of filaments they are selling, but so far in my tests, I’ve found that I don’t need my go to brands any more. I can grab a roll of MG, thread it up, and I know exactly what it is going to come out like.

When I add in the fact that MG is less expensive than what I usually buy, well, that’s just icing on my cake, sprinkles on my donut, gravy on my fries, well, you get the idea….:-)