A new hot end

I decided to replace the hot end on my Folger printer with an E3D. The model I went for is the E3D lite6. The full E3D v6 allows you to go to hotter temperatures, and as I rarely print anything other than PLA, this isn't much of an issue. Besides, you can iteratively transform a lite into a v6 by replacing some of the parts. I bought mine from filastruder, and they delivered promptly, with the trademark pack of Gummi bears.

The E3D lite6 comes as a kit. Assembling it is fairly straightforward, and there's only a couple of things I found tricky. One was keeping the thermistor insulation in place as I tightened the mounting screw for it. A bad of glue might have helped. The second was getting the PTFE insert in solidly, as it tended to slip back a little as I pushed the collet on. The instructions recommend holding pulling the collet up with a fingernail as you push the PTFE in. A third hand would have helped to hold it all steady while I did this. As the instruction say, the screws for the fan are tight - very tight, in fact, and they didn't got all the way in. The fan is a little noisier than the original one, with a slight hum which could get annoying. I was a little nervous about the step of heating the nozzle to 245C then tightening it up with a wrench. It turned out to be easy and I didn't end up with the third degree burns I was expecting.

There are several good mounts for E3D on the Folger extruder, such as this one. I didn't have all the parts I needed for it, and decided to go for something simpler, by simply replacing the aluminium block which holds the hot end in the original extruder with a printed block that can hold the E3D. Although this sounds simple, I ended up going through many failed versions before I got something that worked.

Thingiverse link for the final version: http://www.thingiverse.com/thing:990300.

Part of the problem was that I initially mismeasured dimensions or misread them from the plans, so I had the mounting holes 1mm further apart than they should be, and the position of the E3D relative to the mounting holes also off by about 1mm in both the X and Y directions. What I also hadn't allowed for is that the front on the motors is not flat: there is a disc of diameter 22mm and thickness 2mm around the motor shaft. The E3D is only 9mm in front of the flat face of the motor, and the top of the E3D is 16mm in diameter. Put all this together, and you either need to make sure the E3D it below the disc on the motor or in front of it. Below doesn't work, as the mounting holes would then cut through the 16mm rim of the E3D, so you have to move it forward. And then the center of the E3D doesn't line up with where the filament comes out of the bottom of the extruder. This is probably all incomprehensible. Here's a screenshot from Blender which maybe clarifies some of the geometry:

The extruder positioning can be solved by moving it forward a tiny amount, which you can do by inserting a washer on each screw between it and the motor. The block is printed in two pieces which clip onto the motor. I mounted it with 30mm M3 screws. They are slightly too long, and the nearest other size I had was 20mm which is definitely too short, so I padded it out with more washers. Here are some pictures of the finished product:

In doing this, I got rid of a fan shroud and a light that I had attached to earlier. The fan is for cooling the object as it prints, and I might add this back if I need it. The light was useful in the early days when I wanted to look closely at what the printer was doing, but I've not made much use of it recently, so I left it off for now. Less weight on the X carriage is probably a good thing. I also changed the way the motor attached to the X carriage, so it is mounted using the bottom two screw holes in the back of the motor rather than the top two. This reclaims all of the extra Z space taken up by the E3D.

Is it an improvement? It's really too early to tell. All I've printed so far are a few test objects. The nozzle oozes slightly, though less than my old one. I've printed down to 0.05mm layers. On a thin wall cube, I don't see the slightly wavy patterns that I used to, though they didn't always show up before.

(Footnote: there is a second version of the mounting block at http://www.thingiverse.com/thing:1030184.)

Filamentary

Debating the properties of filaments seems to be a popular occupation amongst 3D printing enthusiasts. I've recently tried out a few different ones, and here are some ill informed and entirely anecdotal observations. Plus the drama of a printer with a blocked nozzle.

I'm using a Folger 2020 with the MK7 extruder as shipped. I've found it to work adequately, apart from having some problems with oozing. You often see a little filament coming from the nozzle before and after printing, and the prints sometimes have spider's webs (very fine strands of filament, that is), particularly where there are travel moves.

The Folger Sample

Folger supply a small amount of PLA to get you started. I don't have much to say about it, except that it worked OK. At the stage I was using it, I didn't know much about choosing slicer settings and providing a good print surface. They recommend 219C, which is much too hot. 185C or 190C onto a bed at 60C with blue tape works better. This, and the Quantum and justpla filaments mentioned later all have a shiny finish.

JET PLA

Most of the printing I have done was with a 1 kg reel of JET PLA from Amazon. The color is a little different from the one shown on the Amazon web site. The raw filament has a dull finish and feels very dry to the touch, and this carries over to the printed objects. I did most of my prints at 185C onto blue tape at 60C. Printing the first layer hotter, as some people recommend, didn't work well - the differential cooling tended to make corner lift on larger objects.

I usually wipe the blue tape with alcohol and it then sticks firmly at 0.3mm and 0.2mm layers, mostly OK at 0.1mm, and it's luck of the draw at 0.05mm. The filament has worked very well for me, and I haven't seen any evidence of uneven thickness, air bubbles etc. I read somewhere that 1kg is about 300m, which sounds roughly right. It would be better if filament was sold by length, as that's what you see in Repetier after running Slic3r. The very end of the reel was not very usable, as it had been tightly wound and wouldn't unspool. Removing it from the reel allowed me to get down to last metre or two. I would definitely use this one again, if it continues to be sold; comments on Amazon suggest it may not be.

ColorFabb PLA/PHA

PHA is a polymer similar to PLA. The PLA/PHA blend, made by ColorFabb, is advertised as having similar temperature and ecological characteristics to PLA, with flexibility similar to ABS. It had some mixed reviews when it first came out, mainly about the consistency of the diameter.

You can buy a sample from PrintedSolid. The pack I got had three colours: a vivid red, sky blue and translucent green. I've only used the red so far, and it looks really nice. I found it worked withe the same temperatures as PLA (185/60). ColorFabb advise a bit more than this. It oozes slightly more than the JET PLA.

It's hard to tell how much difference there is in the mechanical properties. I printed a thin wall cube (just the side, no top and bottom), and compared it to PLA by pressing on opposite corners. It feels like it takes slightly less force, though this is a subjective judgement. Flat surfaces of it maybe have a slightly softer feel than PLA.

I like this filament. It is more expensive than plain PLA: the JET was about $20 for 1kg, and PLA/PHA is $39 for 0.75kg, so it's about twice a much. I'll probably use it again.

Gizmodorks PETG

PETG, which is not the same as PET, is said to be more flexible than PLA, again more like ABS. There are a few different makes of it, and they may have some different temperature characteristics. Gizmodorks make and sell it and you can get a sample from them. They recommend 215-235C. I started at a lower temperature, around 195, as it was already oozing from the nozzle. This proved to be a mistake. Part way through a long print, I was admiring how delicate it was - you could hardly tell anything was coming out of the nozzle. Well, that was because nothing was coming out of the nozzle. It was totally clogged. Heating it up and trying to force more through did not work. Eventually I cut the filament off, removed the front end from the extruder mechanism, heated it to 230C, and pushed the remaining filament through with a welding tip cleaner. This forced most of the filament out of the nozzle and the rest of the clog stuck to the cleaner. I was worried about damaging the nozzle or its liner, but I think I got away with it.

It was hard getting the first layer to stick, and I only managed first layers down to 0.2mm. Subsequent layers at 0.1mm were OK. Raising the temperature to 225C or 230C helped, with the bed at 75C or 80C. Maybe a higher bed temperature would also work. I just can't get the bed temperature over 80C without waiting a long time. The filament is very oozy and gives a lot of spider's webs and similar junk. I printed some gears and needed to spend some time cleaning them up spurs from them before they would work.

On the same thin walled cube test as above, it is even more flexible than PLA/PHA. I don't think I would use PETG much, at least with my current hot end.

Folger ABS

When I originally ordered my printer, I got a roll of ABS from Folger at the same time. I haven't wanted to use it because of the smell and fumes. It's not that they are very bad, just that I prefer (and my wife strongly prefers) not to have them in the house. I printed a few very small objects, at around 240C/80C. I am using blue tape. This isn't a good foundation for ABS, and it limited me to 0.3mm layers if I wanted them to stick. The smell is OK, though for longer prints it might not be so good. One the flexibility test with a thin wall cube, it's less flexible than PETG, and about the same as PLA/PHA, with the same disclaimer as before about subjectivity. There was a lot of nozzle oozing between prints. I have no plans to try it further - this was a proof of concept run to see what it was like.

Quantum 3D PLA

Quantum sell what they assert is high quality, low cost filament. You can get a sample from them for the cost of shipping. I got some warm yellow PLA. It has a nice feel to it, and prints well at my usual 185/60C. Seems good, nothing else to say about it.

justpla PLA

Finally, I bought a 1kg roll of PLA from justpla, via Amazon. At the time it was on a very cheap deal ($10) which seems to have ended. Perhaps it was clearance. I got yellow, a slightly translucent lemon yellow. Again, this seems to be printing fine. It's interesting that the Quantum site has an analysis of how consistent the size of filament from various sources is, and they rate justpla very poorly. I took a few measurements, and they have all been very close to 1.75mm diameter so maybe justpla have improved. A posting on the forum suggests this might be what Folger sells and notes some problems. So far, it's been OK for me.

(Later edit: after using justpla for a while, there's a good thing and a bad thing. The good thing is that it sticks really well to the heated bed. The bad thing is that it tangles easily and I often need to help it unspool.)

To finish off, here's a gallery of some of the things I printed during these experiments. The yellow boxes are model Google Search Appliances.

The X/Z Rebuild

Over the weekend, I rebuilt the X/Z axes on my printer using the design by wderoxas, using the STL files here and here. In summary what this does is:

• move the motors above the frame of the printer, thus reclaiming some vertical space.
• replace the 5mm threaded rods by 8mm lead screws for smoother and more accurate operation.
• place a bearing under each motor coupling for support.
• replace the extruder carriage with one that has four bearings and a better grip on the GT2 belt.
• replace the X axis end pieces (motor mount and idler) with ones suitable for the lead screws and which also have screws to hold the bearings more tightly.
• add an X belt tensioner to the idler.

Here are some pictures of some of the parts and the overall construction.

I bought the lead screws and the 608ZZ bearings that go under the motors couplings from Bangood, and the couplings themselves from Folger. I got new LM8UU linear bearings from MakerGeeks.com. They came very oily, unlike the original Folger ones which were quite dry. I also smeared a small amount of white Lithium grease inside them using a q-tip.

I printed all the parts myself. Before taking the printer apart for the rebuild, I checked the prints: were all the holes big enough for the M3s screws, did the bearings fit, did the chrome rods fit, etc. Initially the chrome rods did not fit in the X motor mount, so I reprinted it with a 0.9 extrusion multiplier. The tensioner was too tight in the idler bracket (that's the one on the left), so I sanded it down slightly. I am slightly concerned that they belt rubs on the X carriage as you can see above, so that may need a little sanding down as well. Note that I have used cable ties on the belt, though they are really not necessary, as the teeth mesh and hold the belt quite firmly.

There were a few hairy moments during the rebuild. I first assembled the motors onto the motor mounts and then tried to join everything up, but it was really hard to get things square. In the end my sequence of steps was:

• assemble the X carriage apart from mounting the extruder. This includes the nuts for the lead screws, but not the lead screws themselves.
• put it on the vertical chrome rods, loosen the top part of the frame, get it in place, and reattach the top part of the frame loosely.
• attach the motor mounts without the motors.
• put the bearings in the motor mounts, then get the lead screws into place.
• attach the motor couplings and the the motors.
• gradually get things square and tighten everything up.

Then do the usual setting of the end stops and levelling the bed.

I made two small additional changes. As I mentioned in an earlier post, the end stop brackets that Folger supply are not so great, as the bracket extends some way above the top of the switch PCB. This can cause the switch to never trigger, as whatever is supposed to hit the end switch (the X motor mount specifically) will hit the bracket first. I adapted the bracket to move the holes where the switch attaches up a bit, so the lever of the switch now extends well beyond the top of the bracket. Also, I adapted the X motor mount in blender to add a small cylinder to the bottom of it, into which a M3 bolt can be attached. Then I added a larger plastic head to the bolt, so now I can fine tune the position at which the Z end stop engages without having to move the bracket. It looks like this:

The configuration in Marlin has to be changed to specify new Z steps settings. I thought the pitch was 2mm, which according to this would mean 1600 steps per mm. It was wildly off, and it's because I didn't understand the specification for the lead screws. They have a 2mm pitch but 4 starts, in other words there are 4 intertwined spiral threads. So one turn is actually 8mm, and we want 400 steps per mm, giving this line in Configuration.h: #define DEFAULT_AXIS_STEPS_PER_UNIT   {80,80,400,97.826}

Does it work? Yes! I haven't printed a lot yet, but enough to see that it looks OK. I printed 10mm calibration cubes at 0.3mm, 0.2mm and 0.1mm layer heights, and even at 0.05mm, which I've never managed to do before (with a first layer of 0.15mm to make it stick). The Z movement is very quiet, and the X movement is quieter than it used to be. I also printed a thin walled cube and a few miscellaneous other objects. I can raise the Z position to 150mm, whereas before I could only go to 120mm before worrying the mechanism would tear itself apart. There were are few clunking noises, probably motor skips, and I think I could just have got to 160mm.

Thank you wderoxas for the designs, and also CheopisIV for these pictures of another build.