Taz 3 Help

I just bought a refurbished Taz 3. This is my first 3D printer, but I have a couple CNC machines, so I’m pretty familiar with most of the concepts, and have been lurking on this subreddit for awhile.

I was doing some test prints and I just can’t get anything all that great out of it. It’s a Taz 3, but has a PEI bed, upgraded 600W power supply, and a few little upgrades here and there. I leveled the bed as best as I could. I actually used some 123 blocks to get it leveled, and that helped a bit. I then set the Z position and got it to where it would lay down the first layer without curling up, or mashing it down. I made a 1cm cube in solidworks and exported it to an STL file and tried printing that. Here’s an album with 3 tests:

http://imgur.com/a/q3uY0

I’m using HIPS (esun). Bed temp is 85C, extruder temp is 230. 100mm/sec is the speed (on the third I tried slowing it down and it didn’t do a lot). I measured the filament and it’s around 2.9mm on average, so I’m using that. Any thoughts? I’ve seen some GREAT stuff come from a Taz, but so far mine’s pretty far from that :wink: I’m using the custom version of Cura, using the Taz 4 profile (there’s no profile for 3).

HIPS seems to be more troublesome to start printing with than other fillaments. My first advice would be buy a roll of ABS and learn with that.

Those calibration cubes look very small. Very small parts are difficult to print without a cooling fan, which the Taz 3 did not come with by default. Normally for larger HiPS or ABS prints you don’t use the fan, but they are large enough that they can absorb the layer heat from printing without melting the underlying layers. The bowing you see in the middle may be due to thermal contraction.

The adhesion pattern looks good, so I would agree that your bed is level and probably isn’t the problem.

The belt tension might be an issue. I can’t tell from those objects. Please print something with a round hole in it. If the hole seems out of round in one direction, you will need to tighten one of the belts. Usually it will need tightening in whichever direction the hole seems squished.

You will also want to run an extruder calibration. It looks to me like you may be slightly underextruding until you reach the top layer. This is as good a guide as any on how to do that: http://www.instructables.com/id/How-to-calibrate-the-Extruder-on-your-3d-Printer/

Also, what infil percentage were you printing at? try 85% for starters to get things dialed in. Don’t start with anything near 100% or very low infill numbers.

Try printing a larger object to eliminate thermal considerations while you are calibrating.

Everyone I see printing with HIPS seems to struggle with it somewhat though. i definitly would not reccommend it as a starter fillament. It is picky about sticking to things, and seems to have odd thermal characteristics.

Cool, I’ll try that. I grabbed some PLA (I had access to a spool). I’m trying a print with that now instead.

One thing I’m noticing is that as the height increases, it seems to be pressing into the part. When it’s laying down the first few layers, I can tell that the nozzle is definitely on TOP of the part, but as the layers increase, the nozzle kinda drags through the part. It seems like the Z axis isn’t properly stepping out of the way. Or, the layers are larger than the mechanical steps.

Also, I noticed the ‘carriage’ is really loose. It seems like the bearings are pretty well shot. I disassembled the X axis and found a LOT of slop in the bearings. I rotated them and it helped a tiny bit, but overall, there is a lot of play in the carriage itself. I’m not sure to what extent the printer was refurbished…

Printing with PLA will require a cooling fan for best results. Without one it’s going to probably look somewhat melty. It also prints at different temperatures. It doesn’t lift at all though, which can make dialing the printer in easier. A lot of people prefer it as a first filament, but you really want to add the fan. Here’s the instructions for adding the fan kit to a Taz 2, which is essentially a Taz 3 in terms of electronics https://ohai-kit.alephobjects.com/project/TAZ-extruder-fan/

If the nozzle is digging into the part, that can be indicative of overextruding. Your Z steps looked fine from the other part. The only reason those would be off is if you had Taz 4 or 5 firmware on a 3, since the 4/5 uses better leadscrews. Your prints would look like squished buttons if that were the case though. Definitely run through an extruder calibration when you get a chance.

If the carriage is too lose, you may need to replace the bearings. one stopgap you can do in the mean time is loosen both bearing carriages and move them either both in to the center, or both out to the edge, depending on where you get the best contact pattern. IN to the center is preferable as that will have the bearings ride on the outer edges of the rods. I would recommend printing a Taz 5 carriage when you get time and get the printer dialed in. It’s lighter than the 3 carriage and will bolt in place.

Since you have a Taz 3, I would recommend you go here at some point soon : http://i-t-w.com/hardware/
and purchase the parts necessary to upgrade your printer to a Taz 4/5 spec. Specifically these X end plates are next to impossible to find, and they only come up for sale infrequently so you may want to snag those if you ever plan to upgrade your printer in the future. http://i-t-w.com/hardware/taz-x-axis-end-plate
They also have the leadscrews which you can source elsewhere, but that’s not a bad price for them.
http://i-t-w.com/hardware/lulzbot-taz-45-z-axis-lead-screw-threaded-rod
and the leadscrew nuts http://i-t-w.com/hardware/taz-45-z-axis-nut-lead-screw-resin-misumi-mtsrr12
The rest of the parts you can make easy enough.

yeah, I know I need the fan, I bought one and should have it next week. so far the prints with PLA look a LOT better. when the part gets small (the tips of things), it gets a bit melty and loses detail, but otherwise it looks much much better.

after this PLA print is done, I’m going to calibrate the extruder. I feel like it might be over-extruding like you said. when it’s doing in-fill, the edges of the part are cupping a bit, and the middle dips down, which tells me that where it’s laying down a full layer (edges), it’s higher than the in-fill, thus it’s over-extruding just a tad.

I got my printer from Jamie at ITW. I asked him if he had any extra bearings. If not, I’ll probably just replace the rods with hardened ones and replace the bearings with actual linear bearings, not sleeves. It would be maybe $100 for everything.

update:

I messed with the printer all weekend and am returning it for another one tomorrow.

I tried some PLA and the results were better, but still not acceptable for a printer of this level. I would expect this quality from a $500 printer on eBay, but not the Taz. The PLA prints were ‘ok’. I used a small computer fan which helped a bit, but I still had the start the print 2-3 times to get the first layer to stick properly and overhangs of any angle are impossible. Also, edges aren’t very clean, edges come up (even with a brim), and the overall finish quality of the prints isn’t great.

We’ll see if the second one I get is any better. If not, I’m going to another brand :-/

If the layers aren’t sticking to PEI you either have the bed the wrong temperature for PLA, you are too far from it, there is some sort of oil residue on the bed. or it isn’t leveled properly. Try 195 - 305 C for the first layer, then drop to 190 for subsequent layers. If you are using a 0.5mm noizzle, use a 0.4mm starting layer thickness. If the bed feels oily, clean it with Isopropyl Alchohol. With the printer heated to temperature, locate the nozzle at the lower left corner and level the corner to the nozzle, using a thin metal gauge as a spacer. Then move the nozzle to the lower right corner, do the same thing, then the top right, then top left. The bed should now be level to the nozzle. Then adjust the height as needed. Run the bedcalibration gcode file until you can get the print to stick uniformly in all corners.

Overhangs in PLA are very fan dependent. Do you have a 40mm cooling fan with the Taz fan duct directed at the nozzle? or are you just blowing an 80mm fan onto the print from the side? Without the proper cooling fan, PLA prints will not come out great on most 3d printers. You can certainly try another brand, but there is a user skill component to printers as well.

After I have the bed level close with a feeler gauge, I print the attached X part several times (slice with an 80 degree infill), making adjustments after each print.

For me, this has been much more effective at fine tuning the level and Z height than the bed level gcode supplied by Lulzbot. I just look at the bottom of the part when it finishes to see which areas have good squish and which is a little “loose” and adjust the corners accordingly. I pay attention to the center of the X to help me determine if the Z end stop needs to be adjusted.

I had some adhesion problems on my Mini a while back when I was printing low bed contact area parts. Lulzbot support recommended I use a cotton washcloth with some 90% or higher isopropyl alcohol and “vigorously scrub the bed.” They said these plastics, especially PLA leave a residue on the PEI that can inhibit adhesion.
bedCalX.stl (2.23 KB)

The parts are adhering (when they’re done and the bed cools, I still need to pry them off with the knife), but they are curling on the sides. I lowered the bed temp and even used a brim, and that didn’t fix it.

Also, I just noticed that the left side Z nut is loose. The brass press-fit nut on the leadscrew isn’t secure anymore, so you can move the carriage up and down. So, the left size is loose, the bearings on the X axis are REALLY loose (there are grooves worn in them, and you can easily rattle the extruder head. The extruder head has also sagged quite a bit, it’s not at a 90 degree angle to the frame, there’s a crack in the wood part on the nozzle, the fan on the enclosure died (it was just getting super hot and heating up the case), and there’s a good amount of play in the extruder gears.

Today I’m exchanging it for another one, and we’ll see what problems that fixes. I had to tweak the retract to 4mm to get rid of strings, and I had my flow rate at 80. Seems like those values are pretty far off from what they should be.

piercet, I hear ya. I knew this wouldn’t be something I turn on and go. Although, the Mini my friend has is pretty darn close to that. HIPS basically doesn’t print. There was no amount of tweaking that even got it close. I’m getting closer with PLA, but it’s still just a toy at this point, it doesn’t do anything usable. Where the fan was hitting the part, it helped quite a bit, so I have high hopes. However, I still wasn’t getting clean edges, and prints weren’t consistent. I would do the same print twice in a row and they would come out pretty different.

I have a roll of ABS too, but the stuff I’m doing is relatively large, solid bodies. So, ABS is probably going to be problematic, which is why I was trying HIPS and PLA.

yeah, if the leadscrew nut isn’t tight, it will tend to lift on the edges of things, which will get you edge lifting. That might be the root cause of the main issue by itself.

The bearings have grooves in them by default, They should look like this: https://www.lulzbot.com/products/solid-polymer-bearing-rjm-01-10mm new. Yours certainly may be really worn and need replacing, but you should also be able to move the bearing carriages to get a better contact pattern.

The strings and extruder gear issues might be contributing to each other. The extruder on that machine might very well have a different hobbed bolt than whatever the original extruder was, and would theoretically also need a different extruder steps value in firmware. If those values are off, it affects quality significantly. The gears should be pretty tightly meshed. if the main gear is wobbling, the hobbed bolt nut may need to be tightened, making sure the bolt still turns freely. if the mesh between the small gear and the big gear is too lose, you need to loosen the extruder motor and slide it in further.

Since you are getting a new one it probably doesn’t matter all that much, but fixing the existing issues would be a good learning exercise if nothing else.

Yeah, my plastic bearing looks like that. But there is wear on the top (where it rode on the shaft). When I disassembled everything and just had the rod and the bearing, if you shook the rod a bit, you could easily hear the bearing rattling. I’d say there’s about 0.01" play in the bearing, perpendicular to the shaft. I rotated the bearings to get a ‘fresh’ spot on them, but the carriage still rattles a bit.

The hobbed bolt looked OK, but the slop in the extruder drive gears could be contributing to a problem. I’m not sure how much slop there should be, or why they don’t just use a timing belt/pulley system to take up the slack that’s bound to creep up with two plastic gears grinding against eachother.

But in any event, I’ll swap printers tonight and see if that works. He’s printing a couple test prints that were giving me troubles, so I can see if it works out. He printed a small test print on the one I bought, and it was kinda crappy, but I just figured it was done on really low quality settings and it wasn’t calibrated, etc.

I swapped out the printer and everything is fine now. I’m still not 100% sure what the issue was, but swapping it with another unit helped. Now my prints are as expected. I still need to tweak things a bit, but I’m happy with the prints now.

Now it’s time to replace some of the 3D printed components with machined parts…

You should check out the Openrail projects in the comprehensive Taz upgrade thread if machined parts are a direction you are contemplating going.

The cooling fan for the control box had quit turning, with replacement the printer is able to print his supplied test model with no problem. :nerd:

The outside of the C.B. was warm to the touch, which it should NOT be in room temp open air. Around 90 degrees the driver chip seems to want to start to miss steps on the motor.

Oh, yeah, that will definitly do it heh.