Author Topic: 3D printer - cheap as chips  (Read 14452 times)

Offline ddmckee54

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Re: 3D printer - cheap as chips
« Reply #30 on: January 07, 2020, 03:54:48 PM »
Jo:

Pete tried to warn you, but it was too late, you're already doomed by the 3D printer madness.

You've got the same problem with the front plate that I had on my first printer.  The tension from the Y axis drive belt causes the plate to bow, your idea to replace it with a piece of aluminum is a good one.  I printed a thick block for mine that does the job.  I found it on Thingiverse, I searched for upgrades to my printer.

Printer maintenance is very important, keep those linear bearings well lubed, otherwise they'll chew up the soft guide rails that are supplied with the kit - DAMHIK!  Keeping the bearings lubed also goes a long way to quieting the printer.  I don't mind the stepper motors singing to me, but I can't stand listening to the linear bearings rattling along.  I wound up replacing all the linear bearings on my printer after about 6 months.  They weren't worn out, just cheap and extremely noisy.

You might be able to straighten the guide rail, if the kit had hardened rails I'd be amazed.  But if you've got replacement 8mm rail/rod it'll probably be better than what was supplied with the kit.

Jo, you're already deep into the 3D printer modifications rabbit hole, welcome to the madness.

Don

Offline Jo

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Re: 3D printer - cheap as chips
« Reply #31 on: January 07, 2020, 05:10:14 PM »
Thanks Don


Printer maintenance is very important, keep those linear bearings well lubed, otherwise they'll chew up the soft guide rails that are supplied with the kit - DAMHIK!  Keeping the bearings lubed also goes a long way to quieting the printer.  I don't mind the stepper motors singing to me, but I can't stand listening to the linear bearings rattling along.  I wound up replacing all the linear bearings on my printer after about 6 months.  They weren't worn out, just cheap and extremely noisy.

...

Jo, you're already deep into the 3D printer modifications rabbit hole, welcome to the madness.

The linear bearings seem to have speed humps when I push the guide rods through them  :ShakeHead: Yes it seems I will be doing a fair bit of modifications before any plastic is melted. Currently I have found a plate of Ali to mount the printer onto and my plan is to screw it down to keep it square and so that the guide bars do not move. I may also replace the bearings  and then the bottom plate and on it goes  :lolb:

I discussed this with Pete when he visited this morning, the money I paid really only paid for the steppers, electronics and the (probably pirated) software to run the thing. I have plenty of Ali so I can make a few bits. Maybe we should start a sweep stake on how long it will be before there are signs of Hot plastic  ::)

Jo
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Offline Jasonb

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Re: 3D printer - cheap as chips
« Reply #32 on: January 07, 2020, 05:28:13 PM »
Sounds like the only hot plastic for a while will be your credit card for all the extra bits you need to get it going :LittleDevil:

Are you sure an disgruntled Elephant did not sit on that bar due to you neglecting castings :thinking:

Offline Mike Bondarczuk

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Re: 3D printer - cheap as chips
« Reply #33 on: January 07, 2020, 05:33:56 PM »
Jo,

The price you pay is related to what you receive, though a shame that the quality seems to be lacking a bit and hindering your ability to melt some plastic into recognisable shapes.

Will be most interesting to see, once the engineering modification stage is completed, how the printer will function in its "raison d'être" and I guess most of us are looking forward to that stage.

Mike
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Offline ddmckee54

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Re: 3D printer - cheap as chips
« Reply #34 on: January 07, 2020, 05:50:07 PM »
Once you get the plastic melting you'll find that 3D printers are quite capable of making their own repair/upgrade parts.  My kit 3D printer has a LOT of printed upgrade parts on it, as does my Wanhao D6 clone.  I started out making parts that I got from Thingiverse.  Then, once I got a little more familiar with 3D CAD, I went more to designing my own parts.  Now I rarely use anything other than my own designs, that way I can control the tolerances and fit of the parts.

One thing that I didn't really consider at first is that we are extruding hot material, as it cools, it WILL shrink.  If you are designing close fitting parts you will need to compensate for this.  Either by scaling up the size of the part in your design, which I would think would just get confusing, or by using the slicing software to scale up the part.

If you've got somebody nearby with a printer it would REALLY help you to watch what they do when they print a part.  Ask questions, pick their brain, the learning curve for an absolute beginner at this is REALLY steep.  There are SO many things that can go wrong and cause a failed print that it gets really discouraging, I know from personal experience.

That said, there is NOTHING like peeling that first successful part off the build plate, even if it is just a calibration cube.

Don

Offline awake

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Re: 3D printer - cheap as chips
« Reply #35 on: January 07, 2020, 08:04:25 PM »
... the (probably pirated) software to run the thing ...

Actually, probably not pirated - there are two or three open source projects for the firmware that runs on the vast majority of 3d printers. Some printers use the open source versions as-is, while some make various modifications (which is allowed by the open source license).

One very important thing to check out, especially on a budget printer, is whether the firmware has the thermal runaway safeties enabled. These are bits of code that check to make sure that when heat is called for in the bed or in the print head, appropriate heat is sensed by the thermistors, and if not, shuts everything down. There have been some infamous examples of cheap printers that disabled these safeties (presumably because they were having issues with false triggering, and it was easier to disable the safety than to fix the instability). Without the safeties enabled, a loose connector on the thermistor can lead to the printer overheating the bed or print head ... and there have been tragic results in some cases (houses burnt down).

For designing items to print ... if you are already using 3d CAD software, you've already got everything you need. If not, there are some open source options that I like: FreeCAD and OpenSCAD. The former is a 3d CAD program that continues to be heavily developed; there are some quirks, but overall it is very capable, and there are tons of tutorials. The latter is a very different animal; it is not CAD software, but rather a programming environment in which you can assemble various solids (including joins and intersections) to make a part. There are times when I find the 3d CAD approach much easier, and other times when I find the OpenSCAD approach much easier.

Whatever software you use to develop the 3d model, you will probably want to save the results as an .STL file. (There are some newer formats which are far more robust ... but have yet to be implemented very widely.) From there you "slice" the model into the gcode commands that will tell the printer how to print. Your printer likely came with a slicer program ... but again, there's a good chance that it is a modification of an open-source slicer. There are two in particular that get used heavily by budget printers, Slic3r (yes, that's a 3 in the place of the e), and Cura. I prefer the former, but some prefer the latter; try them both and see which you like best.

And of course, any or all of the above may be things you already knew, and if so, I apologize! But hopefully they will be useful for someone reading this forum, to help someone get started - basically, the above is a quick overview of the key things that were part of my learning curve a couple of years ago.
Andy

Offline JonC

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Re: 3D printer - cheap as chips
« Reply #36 on: January 07, 2020, 08:34:35 PM »
Jo,

Your printer is almost identical to mine and I would recommend one simple modification. Because the M8 lead screws for the Z axis generally run out, this creates Z wobble as the build gets higher resulting in offset layers and poor finishes on walls.
To get around this I simply made the nuts (shown in your fifth photo down, previous page) so that they are floating, simply by opening out the four holes each side that the retaining cap heads go through and then loosing them so that they are there to prevent rotation of the nuts only. This lets the screws and nuts orbit around as they raise but allows the printhead to follow the rods and linear bearings only.

Hope this helps and if you face any other problems, I'm happy to help.

See 1/4 Scale DFV Engine posts for some of my prints.

Jon
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Offline Jo

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Re: 3D printer - cheap as chips
« Reply #37 on: January 07, 2020, 08:56:21 PM »
 :thinking: I think I understand that Jon. What you are saying is that the two vertical leadscrews have two nuts, which are held in place by four cap head screws. Because the threaded vertical rods are not straight  ::) if the feed nuts can float side to side then any bend will not move the print head.

I had already noticed this problem and had been trying to put off thinking about how to solve it, thanks for the suggestion  :ThumbsUp:


To avoid confusion: I have gotten what I expected so far with this printer. Like most Chinese made things: it is cheaply made with poor quality control but that has potential for improvement.

Jo
 
« Last Edit: January 08, 2020, 04:17:14 AM by Jo »
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Offline JonC

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Re: 3D printer - cheap as chips
« Reply #38 on: January 07, 2020, 08:58:54 PM »
You got it  :ThumbsUp:
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Offline deltatango

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Re: 3D printer - cheap as chips
« Reply #39 on: January 07, 2020, 09:05:53 PM »
Hi Jo,
As to the "time to first print" sweep it took me three days to assemble my GeeeTech Prusa i3 clone, then three weeks before it did anything useful. Apart from using Perspex instead of plywood my machine is very similar to yours.

JonC's suggested modification re the floating nuts is a good one, pretty much essential if the z drive threaded rods are as straight as mine weren't. There are ready-to-print models for these on Thingyverse.

The firmware may well be one of the versions of "Marlin", if so then this gives a lot of learning opportunities. "Awake" has already made one vital point re the thermal runaway detection and there are a lot of others to explore that will improve the performance (e.g. tuning the built-in PID control to reduce overshoot at sharp corners) but those may be best left for later! In my machine the controller is built around an Arduino and the firmware can be edited with the Arduino IDE but Visual Studio worked better for me.

Good luck  - I'm hanging out to see the first calibration cube...

David

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Offline Jasonb

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Re: 3D printer - cheap as chips
« Reply #40 on: January 08, 2020, 07:44:36 AM »

To avoid confusion: I have gotten what I expected so far with this printer. Like most Chinese made things: it is cheaply made with poor quality control but that has potential for improvement.


Certainly true for the bottom end of the price scale but you can pay more for products from china that will work straight out of the box, Think I got my CNC mill cutting the day after I got the licence for the Mach3 and it also came with tidy wiring and put together but I would not normally consider that at the bottom of the price scale.  ;)


Offline Jo

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Re: 3D printer - cheap as chips
« Reply #41 on: January 08, 2020, 08:44:15 AM »
….. but I would not normally consider that at the bottom of the price scale.  ;)

Not many people pay over £7K for a Chinese milling machine  ::) at that price it cannot be claimed to be a DIY tool, it better be good.

I realised the first fib this morning on this machine: Yesterday I had been attempting to level the bed and managed to get the stepper motor to 190mm when it made a nasty noise  :headscratch: What had happened was the head had hit the framework on the opposite side.. The machine is claimed to have a printing area of 220 by 220 - Yes the bed is that size but the printing area is only 190mm wide  ::)

If they had set their slicer to 220mm print area rather than 190mm this would also account for why I have seen a few people complaining about these machines not printing in the centre of the bed but slightly off to one side  ;)

Jo
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Offline jadge

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Re: 3D printer - cheap as chips
« Reply #42 on: January 08, 2020, 09:48:59 AM »
Not many people pay over £7K for a Chinese milling machine  ::) at that price it cannot be claimed to be a DIY tool, it better be good.

Oh dear.  :embarassed:

I made my first self-designed part within an hour of getting my 3D printer. Although to be fair I was already proficient in 3D CAD.

Andrew

Offline Jo

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Re: 3D printer - cheap as chips
« Reply #43 on: January 08, 2020, 01:07:51 PM »
I made my first self-designed part within an hour of getting my 3D printer.

I assume you paid more than £70 for it and it came fully assembled  ;)


Having taken my bottles for refilling recycling I was lucky and found a couple of glass fronted photo frames going for recycling that are the same size as the hot bed and have acquired them in case those four strips of sticky tape on the hot bed with their gaps between them  :headscratch: are not fully suitable.

Jo
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Offline Jasonb

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Re: 3D printer - cheap as chips
« Reply #44 on: January 08, 2020, 01:23:01 PM »
As I said Jo it was not cheap (although I got it for free) but does show that the sweeping statement that "Most thing Chinese are cheaply made" is wrong, the cheap Chinese is cheaply made, the expensive can be very well made and there are lots differing levels between the two extreams. You pays your money and get what you pay for. As to whether the KX-3 was good I think JS used to make parts for Rolls Royce on one of his and even the more demanding Myford owners buying his dividing plates were happy with them :LittleDevil:

« Last Edit: January 08, 2020, 01:29:23 PM by Jasonb »