gr5org
21
No one seems to understand how damn important open source is until they own a printer. Owning a printer from a company that blocks you from using other software with it really sucks. Not allowing you to hack it or add third party nozzles or third party filament or tweak the firmware or use a friends plug in and so on - really sucks.
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gr5org
22
You are always going to have dimensional issues with FDM printers - itâs the nature of the plastics and the way it is laid down. The worst offenders are going to be vertical holes. There are 3 reasons vertical holes are much smaller than expected but the primary reason is this:
PLA (which is the best, easiest material to work with for prototypes - itâs just as strong as ABS and doesnât warp as much and for other reasons) has a glass temp of around 52C. But you print it around 220C. It has a roughly constant density/temp profile and shrinks quite a bit between 220C and 52C. This happens in milliseconds so the head hasnât moved very far as the trace of filament is laid down. Molten PLA isnât like water - itâs more like snot - it sticks to itself. Like hot glue that is still hot. So as it shrinks it turns into a kind of liquid rubber band. When laying down this âliquid rubber bandâ in a tiny circle it wants to stretch inward (before it even becomes solid). It doesnât stretch far because it attaches to the layer below⌠which also tried to stretch inward. You get a relatively vertical walled hole but a 3mm hole will be about .4mm smaller than asked for. Yet a cube will have walls exactly the right dimension (or possibly it will shrink by about .3% as that is how much PLA shrinks from 52C to 20C).
There are other factors but this is one of the biggest. Another one is that external corners tend to be too thick/large. Especially if you print fast with the Ultimaker because of itâs bowden tube which stores presssure in the nozzle. What happens is as it slows down for a corner it over extrudes briefly (for a few mm) and then as it accelerates out of the corner it underextrudes. You get a round blob/bump along vertical convex corners because of this and parts might not fit.
The fix is to adjust the CAD but if you want to use the same CAD for a cnc milled part (or cast part) and also for FDM PLA you will be frustrated. You could of course chamfer the exterior corners that are critical and the part will work for both aluminum and plastic (if an air gap is allowed). Or you can print nice and slow (say 30mm/sec). For vertical holes - if you use something like solidworks you can parameterize all vertical holes (but seperate parameter for horizontal holes as they donât have the same issue) and have a different parameter for CNC parts versus FDM parts.
gr5org
23
Zortrax is great but you probably only want to ever print ABS with Zortrax. Itâs really optimized for ABS. Which is a great material. PLA is also a great material to print with. The prices and strength of both materials are great. For most printers, PLA is easier to print with.
gr5org
24
>But look at those corners â they are both rounded and bowed.
Absolutely - thatâs a problem if you print any faster than 25mm/sec due to the nature of the bowden and how it stores pressure. This is definitely a problem for someone who needs really good tolerances and I donât know the solution other than software and I donât know that anyone deals with this in software. yet.
For most prints itâs okay if the corners stick out a bit, but not if you have many parts that need to fit together with tight tolerances.
The calibration cube was not optimized for accuracy of the corners. I wanted to test the top surface but was happy to see that the tollerances are still that good.
The material has a bit more to do with dimensional accuracy than the printer. I calibrate my printers for EACH roll of filament and can get some really accurate parts if I am using good filament.
Yes, when I am printing prototypes, I am printing slower than $20K+ printers but for most, the difference in accuracy is negligible to the difference in price.
You will not be able to calibrate a CubeâŚstay away from closed source printers.
I have both printers running.
First setup on UM2 is faster. 10 to 15 minutes before the first print. Print quality is very good!
With this machine you can use a wider assortment of filaments.
My Cube Pro Trio was a bit more complex. 1 nozzle was not correct adjusted. I got superb support from Cubify and could correct it very easy.
From then on it is working just like plug & play.
The advantage is: I can work with 3 colors at the same time or use a different support material.
OK the filament is expensive. But it works quite good with a minimum of shrinking due to cooling. (The complete build chamber is heated!!!)
Yes you can not trick the machine because you have to use the special software and firmware from Cubify.
But for me the most interesting point was: put the data in and wait for the print with some coffees and without any problems.
Finally: I like both printers for what they do.
I owned a CubeX Duo and the hardware and firmware were complete garbage. They would never divulge how much filament you get for the $100 cartridges but it turns out it was around 0.6 kg which put it around $160 per kg. Huge ripoff. And the prints had at least a 90% fail rate. I was never so glad to get rid of a machine as I was that one.
I suggest that you read the forums of any printer you consider buying before you invest your $$. You will see what works and what doesnât if you go to the main user group forums for each machine. Be careful to not just read things that are what you hope to hear. Forums have a way of delivering a very sobering message since no printer or manufacturer is without problems.
I was leaning toward buying a UM2 recently because it gets a lot of praise from its user group. Its certainly a well sorted machine. However, after I researched the UM2 and the Zortrax M200 I bought the Zortrax. My Zortrax has been spitting out perfect parts for three days now with ZERO failed parts. I previously owned a CubeX Duo and currently own a Lulzbot TAZ, MakerGear M2, Form1+ and a Zortrax M200. The Zortrax is my go-to printer. From time to time I use the Form1+ for certain kinds of parts that its better suited for. However, the Zortrax is the most reliable printer I have and the print quality is the best Iâve seen. The print quality of the Zortrax rivals that of parts I buy for work from commercial companies. I just talked my boss into buying a Zortrax for work. It was a very easy sell after I showed him the parts I printed on mine. Zortrax sells their ABS filament at $20 per spool (0.8 kg of filament) which is a very good price for filament that you can trust. They also offer stronger and slightly more stable version of their ABS filament and clear filament for $50 a spool. All of my prints so far have been on the $20 filament and they are freakishly perfect.
If you want to print with filaments outside of what Zortrax offers then the UM2 might be the better choice because it gives you a lot more control over the machine so you can try any filament available within the temperature range of the hot end. Personally Iâd rather not have a lot of controls and just spend my time printing perfect parts with less filament choices but I understand thatâs not the case for everyone. I think both the UM2 and the Zortrax both have excellent user group feedback. After my first experience with CubeX and their price gouging for filament Iâve never considered them again.
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Dave, you should check out the Zortrax M200. IMO, the quality of prints my Zortrax is putting out rivals that of the FFF parts I buy from Quickparts.com. It is limited by ABS shrinkage issues for large size prints that are associated with non-heated enclosures but most parts come out pretty much perfect with no hassles. It uses a ball screw for the Z axis so Z dimensions come out +/- 0.005" and often better. XY tolerances depend more on the height and geometry of the part but they are generally between +/-0.005" to +/-0.020 for very large, tall parts.
I printed an enclosure yesterday with the lid designed with zero tolerance fit. The lid snapped in with a light press fit. We are going to buy a Zortrax to use for prototyping at the engineering firm I work for to save much of the $20k per year we spend having plastic prototypes fabricated. We have a Form1+ which has paid for itself many times over but the parts coming off of the Zortrax are so much stronger I think it will be our go-to printer now.
from the left: #CubePro (PLA with INF), #CubePro (PLA), Makerbot (PLA)
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