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Archive for June, 2017

27
Jun

M.G. Chemicals PETG

After renovating the backyard last year, I installed some solar lighting.

The lights came with a plastic spike that pushed into the ground but I didn’t use them.

One reason was because that would have either put them in the planters where the solar cells would be blocked by the fence so no charge, or on the lawn where they would have to be moved every time the lawn was mowed.

On June 24th we had a scorcher of a day and Carol pointed out that the lights seemed to be listing. Some to starboard, others to port…and at a fair angle too!

Initially I thought the 3D printed mounts I’d made last year had come loose and to some point that was true.

Ultimately what had happened was that the screw holding in the mount had reached the PLA’s glass transition point, with the stress of the heavy weight of the solar light (they have a glass lens; not plastic), it was enough to start the topple syndrome.

IMG 1172

The outside temp was 30C. When I took the mount off the post rail, the screw felt a lot hotter than that.

Of course there was no use reprinting more mounts in PLA if they were only going to last a year.

Then I remembered I had some M.G. Chemicals new improved PETG.

IMG 1174

The glass transition point is 25C higher than PLA! I redesigned the mounts to make them taller and a thicker base for the screw to sit in.

IMG 1173

I started printing and replacing the mounts. After they were all done, it was time to sit back and wait.

IMG 1177

I only needed to wait until the next day. The temp outside climbed to 31.2C, and the solar lights stood like sentries without a movement.

The new mounts worked out perfectly.

One thing I should note if you try something like this, I used a fan on one print. PETG seems to cool off quick enough anyway so really the fan is more or less to stop stringing. I found the best way to print these small mounts is slow and no fan. Excellent adhesion between layers and almost no stringing in these small items.

26
Jun

3D Printer Noise – Not a Fan

One of the things that 3D printer reviews tend to gloss over is just how loud the popular Cartesian or Delta 3D printers can be. It doesn’t matter if the printer is a typical open frame type or closed up in a box, quiet is not a word that comes to my mind.

Given that the speed of the printer will affect the steppers, thereby transmitting said vibration through the printer frame itself, there’s not a whole lot you can do about some of it. Granted there are stepper dampers that are said to “lessen” the vibration transmission, or isolation feet so the printer doesn’t use the table/bench it’s sitting on as a “speaker”…

I tried the stepper dampers, ah, yeah. Didn’t seem to do as much as I’d thought. The budget dollar store rubber feet had a far greater impact though.

Fan Noise

However, what about when the printer is simply sitting idle? On a delta printer there is a fan on the hot end that needs to run continuously. Replacing that fan with a ball bearing low db fan is a good move. The original one that came with my printer sounded like a cement mixer.

Typical specs for the “cement” mixer would be as shown:

Noisy Fan

Considering the specs were from a ball bearing fan, it’s a noisy little brute. Basically, look for a 6,000 RPM, 0.15A max, and dB-A of 21 (lower is better). If you order these from eBay or some other equally sketchy source be aware that any specifications you see are going to be questionable. At best.

I picked up some Coolertec case fans OW4010DFS-2P hydro bearing, 15dB-A. You don’t more than 5 or 6 CFM. NASA wind tunnel fans not needed. The Coolertec fans? Wonderfully quiet, darned hard to get.

IMG 1175

Power Supply Fan

The second culprit, major source of annoying white noise is the power supply fan. On a typical 360 watt (12V 30A) switching supply I found that the fans on most of the ones I’ve worked on or bought, run all the time. Loud!

IMG 1151

I’d removed all the grating from one supply, replaced the fan with a quieter one and it’s still noisy.

By some sheer freak of nature I ordered a power supply from Amazon and when I installed it, the fan wasn’t running. I thought it was fried from the get go. I checked the voltage and it was fine. Once running for a while during a print job the fan would come on, run for a minute or two, shut off again.

I started to investigate why this happened.

The majority of these 12V 30A supplies “specify” a thermal controlled fan, so as the power supply heats up from current draw, the fan will cut in and cool it off. Oddly enough even though thermal control is stated, my experience is that the fans run all the time.

So….why? That’s the question.

Thermal Control

I took apart a power supply where the fan cycled and one where it didn’t. Started to look at what the differences were.

IMG 1153

It was surprising to find that the majority of the ones I have, from 4 different sources/companies, all use the same PCB. Or a minor variation thereof.

I tracked the difference down to a jumper of the “fan runs all the time”…see that jumper RT2? Yeah, there is supposed to be a thermal relay component there. But hey, that cost .97 so…jumper. Or as I found with a lot of offshore stuff, cost, not quality.

IMG 1154

The part that’s missing is a simple thermal relay, N.O. (normally open). It closes at 45C and opens at 33C.

KSD9700

To get the PCB out of the case is a little tricky. Remove the two screws that hold the heatsink bar on the MOSFET’s at the end and edge of the case.

IMG 1155

I found on my power supplies the screws were two different lengths. Thus, whatever comes out of the spare parts bins when they were assembled. There is an aluminum plate with some heat sink material on it, that needs to come off the side MOSFETs (where the thermal jumper wire is). You need the wiggle room to get the PCB out.

Next are the PCB screws. There should be five in total. One in each corner, one in the middle. Mine was built on a Friday at 3 minutes before quitting time, I only got four screws.

IMG 1156

To get the PCB out, slide it slightly forward (so the back edge of the PCB will clear the rear inset aluminum; about 1/8″). Notice on the side where there are no MOSFETS the PCB is notched so I just lifted that side up, but left the opposite edge with the MOSFETs where it was. Sort of rocked it back towards me. It’s a tight fit so don’t get heavy handed with it. It goes back in the same way.

Power Spply PCB

Once out, it’s easy to work on.

Thermal Relay

If you’re thinking the relay would attach to the case or the MOSFETS, ah, nope. It doesn’t. It actually goes inside the toroid coil on the PCB. And you glue it in there.

Start by bending the leads on the relay.

IMG 1159

Now you need some “glue”… but you want thermally conductive glue.

I found some on Banggood and eBay called “silicon thermal plaster”. It’s not inexpensive either and I decided that since I didn’t know what it was, couldn’t find any specs on it, and lastly didn’t feel like waiting for months to get it, I’d source somewhere else.

Which lead me to M.G. Chemicals. Who, oddly enough, seem to have a wonderful assortment of off beat items that fit exactly what I need.

One of which happens to be called, “Thermally Conductive Adhesive”.

IMG 1161

M.G. sells two kinds of this epoxy (it is a two part adhesive). One is called paste the other is flowable. I thought I would need the paste, but that was not available. I got the flowable instead.

I was hoping it was not as runny as five minute epoxy and I wasn’t disappointed! It’s about as “flowable” as silicon. I.e. you goop it, it stays gooped where you goop it. How’s that for technical terms…

As with the “silicon plaster”, 25ml isn’t inexpensive either. As in $31 CDN.

BUT, if you’re doing a couple of your own power supplies, a couple of friends as well, it cuts that cost down.

Seriously, and I do stress this point, when you buy something from a reputable company who supplies MSDS sheets, you know using it won’t cause a third eye to grow on your thorax three weeks later.

I got two mixing tubes with the adhesive and let me tell you, not only do they mix the epoxy PERFECTLY, you’re going to get a bonus hand work out shoving the mix through the tube…:-) The tubes are obviously a one time use but if you were doing a small restricted access and several of them, arrgghh matey, they be worth their weight in gold.

Otherwise, just put in a piece of paper and mix it like you do five minute epoxy.

Put the thermal glue on the edge of the toroid coil and don’t over use it. You don’t want to plug the air off from getting through the coil. Mine actually looks thicker than it really is. Maybe because I used a popsicle stick to put it in. I suggest a Q-Tip…

IMG 1162

The epoxy said it had a 45 minute working time and a 24 cure time. I left mine for about 6 hours to setup, then proceeded with the wiring. When I checked the joint 24 hours later, it was just like epoxy, hard as a rock.

Relay Wiring

Cut the jumper on the PCB and remove the two short wires.

IMG 1163

I used a solder sucker to clean out the holes…

IMG 1164

The relay is not polarized so there is no plus or minus to watch for. Simply solder in the two leads from the relay.

IMG 1165

Reassemble the PCB in the case, put the aluminum edge plates back in, PCB screws, case screws, etc.

IMG 1166

Make sure the relay wires are not chaffing on the heat sink clamp (yes, it’s a typical Mickey Mouse way the offshore guys do it) and button the case back up.

Rather than pop mine into a 3D printer I grabbed a bunch of LED strings and tested it.

IMG 1167

Kind of seasonal I must say, bright was the other thought…but sure enough, 10 minutes later I tested the heat of the edge MOSFETs, 45.6C, the fan came on, dropped the temp down to 33.2C and shut off. It works perfectly.

3
Jun

3D Printing Slicers

Having been down the somewhat unpaved road of 3D printer slicers over the past couple of years, I’m always on the look out for something that improves a 3D print without having to resort to sacrificing a spool of filament in an open fire pit on a full moon. At the stroke of midnight.

Let me preface this by stating I’m a delta printer guy. I’ve used cartesian’s but my go to printers are both Kossel styles. Built by me. So I know them well.

Slicing Software

There are those who seem to be able to make anything work, either right off because the software “works” like they do, or they stick with it long enough to learn all the nuances of it and master it.

I gave CURA a fair shake, kind of got it working, but while it felt pretty with it’s GUI, mining down to the settings I wanted to adjust with got annoying. I got the feeling it wasn’t designed for delta style printers in spite of the fact that many are using it on delta printers.

Venturing even further down the path, I bought Simplifry3D. Advertised as the be all and end all for slicing. Plug and play. Easy to use. Excellent documentation. Yeah, my experience dictates that would be four strikes against them. Make it five if you want to include the absolutely pathetic tech support.

Still, honestly, you have to try these things because what works fabulous for you may not work for others. Or vice versa.

After the roads I travelled down, it was nice to get back to Slic3r, even if there’s some pot holes in the road that need fixing. Or as someone said, “Better the devil you know than the one you don’t”. Thus I kept going back to Slic3r.

Slic3r

Slic3r hasn’t changed from the 1.2.9 version since June 2015. In software lifespans, two years is an eon. Mind you it is open source so you take what comes.

Slic3r is working on a 1.3.0 version and I suspect in time it will appear since they are pouring a lot of hours into it.

PRUSA Slic3r

Last year PRUSA forked Slic3r with the intention of making it work better with their own brand of printers. This got my attention since the work that PRUSA stated they’d be doing would be fixing up the various parts of Slic3r before adding in all their own bells and whistles to better suit their own printers.

With every release PRUSA has done, I’ve downloaded and run to see how it works with my Kossels. I’d be the first to admit this is not exactly what I would ever advise anyone to do. Me, I’m curious. Just a darn good thing I’m not a cat.

Some of the releases were, ah, how to put it, scary. The print head moving like a spasmodic hummingbird, or moving at the speed of the next ice age. Oh yeah, some issues for sure.

However, over time, each release got a little bit better. I’d check the forums to see what others would experiencing and see that would relate to anything I’d be doing and in most cases, nope. Delta printers are different.

Since the first week in April I’ve been using PRUSA’s 1.34.1 version exclusively. The quality that I am getting out it exceeds what I can get out of the 1.2.9 version of Slic3r. Admittedly some of the settings in the PRUSA version are different than the settings I used in Slic3r.

First off, the download link for the PRUSA 1.34.1 version.

Next the simple settings changes are in 3 areas, assuming you’re using the Expert settings in Slic3r like I am…

Preferences

Preferences

The USB serial connection is if you want to print from Slic3r via USB. I haven’t tried it, no idea if it works or not. I use Octoprint so everything is wireless here.

Layers

The only settings I needed to change here is in the “Quality” section. Specifically the “Avoid Crossing Perimeters”. Thin wall works sometimes, not others, much the same as vertical wall thickness. Normally I leave them unchecked and I’ll check the Plater–>Layers view to see how things look, maybe toggle them on or off and recheck.

A very nice edition is the SEAM position. If you want the seam hidden at the back of the print, just select REAR for the seam and it’s done. Works very nicely.

PS 1 Layers

Infill

For the infill, again, the only change I made was where it says, “Only retract when crossing perimeters”. I have it checked.

The rest are merely the stock settings I used all the time in the 1.2.9 version of Slic3r.

PS 2 Infill

Summary

One thing I would suggest if you want to travel this road, save your PRUSA settings with a unique name so you know they are specifically for PRUSA version not the 1.2.9 version of Slic3r.

I started to name mine like PRUSA_50403…shorthand for 50 infill speed, 40 perimeter speed, .3 layer height. Works well.

PRUSA has since released two more revisions but the current one is working so well, I haven’t felt the urge to try either of them out. Like they say, you can’t fix it if it’s not broken. Then again, maybe I’m just not trying hard enough…