3D Printing - whether to buy, what to buy and how to use it?

Paul_H

Western Thunderer
I have been getting vertical "corrugations" which as far as I can make out is "chatter" from which ever axis step motor isn't moving at that time
That's often explained by differences in printing speed caused by the head slowing down for overhangs, eg the strapping and bolt heads. Occasionally when quality is important I'll dive into the settings and set every speed to the lowest speed in the settings chosen.

Another issue can be vibration on changes of head direction when printing fast. There are calibration routines to tune this, Bambu printer have a auto tune function as standard.

Generally I prefer to break designs down so they all print on the horizontal as that tends to make surface details crisper. Maybe not so easy for this design when you have detail on the inner faces though.
 

simond

Western Thunderer
Toolbox for the X2D toolkit. This is one of a million free downloads of variable utility available on the Bambu site.

PLA, 0.4 (standard) nozzle. It took about 4 hours to print the three parts all in default settings.
I can see the lid and clip being re-used, and alternative bases being designed to suit other sets of tools. This or another of the available designs.
I think it did tell me how much filament it used, but I didn't make a note. It weighs 180g so I guess about £2.30, not “cheap”, but given a specific toolset, and will be used hopefully for years, probably quite good value.

This also suggests that the modelling uses (eg timber wagons) will be quite economical. It’s never going to replace resin, but I’m sure there are applications for which it’s much more appropriate, Templot COT track being high on my list.

image.jpg

image.jpg

best
Simon
 

Rob R

Western Thunderer
That's often explained by differences in printing speed caused by the head slowing down for overhangs, eg the strapping and bolt heads. Occasionally when quality is important I'll dive into the settings and set every speed to the lowest speed in the settings chosen.
This seems to be different to the "speed change" issue, I will try and get a photo but it is a regular, constant pitch vertical line, on all 8 faces. My sons printer (same model) has the same issue.
 

simond

Western Thunderer
As promised, report on the first model print. It would be a little too negative to suggest it’s a curate’s egg, but there is clearly room for improvement.

image.jpg

The wagon floor partially unstuck itself from the build plate, so is entirely scrap.
The hinges for the door end likewise did not print, but I think that is at least in part my incompetence rather than any fault of the process.

The rivet detail on the body seems excellent, and I’m struggling to see any layering at all.

image.jpg

It has to be said that white on white is difficult to photograph. There are some bits of fluff in parts, mostly where the support was, and easy to remove. I shall print the next one with the hinges separate, and as they won’t be in the way, I can print it upside down, which will avoid the support, I think.

image.jpg

I’m not sure quite why the slicer added support to the solebars - I wonder if they were not actually properly flat on the build plate as there is a layering effect on the outside which should not have happened. This has rather messed up the inside faces, but the outside detail is really pretty good, I don’t think anyone would complain at these axleboxes and springs, particularly for a “layout model”

image.jpg

So far, so good. The faults are all resolvable, and the process is much less messy than resin, and of course, the resultant parts are much more robust. Around 50g of PLA using an 0.2 nozzle. It took nearly 8 hours (but I was doing other stuff, so who cares?), but the wagon body, floor and solebars used less than £1 of filament.

The next stage is uncharted territory…. I’m going to try to print buffers, coupling hook and wheels in ABS on the basis that they don’t actually need to be metal. I’ll use piano wire for the axles but will print the waisted shape of an RCH axle.

I have not yet sorted the details but printed-in-place springing for axles and buffers should be feasible. Maybe even printed axle bearings. I’d like an RCH 7-plank wagon for well under a fiver, and I’m confident that it’s possible.

And thinking back to my MICA project, I think a 7mm clone of the old Peco Wonderful Wagons, with a printed, laser-cut card body on a 3DP body former and chassis is probably easier than it was.

Further developments to follow on my workbench thread.

best
Simon
 

simond

Western Thunderer
Hi Rob,

all my own work!

I’m lucky enough to have Solidworks experience, and a licence, for my work and can use it at home as I wish.

Following @adrian suggestion, I’ve been looking at FreeCAD on the basis that when I retire, my employers might not be quite so generous! There are non commercial Solidworks licences available at reasonable cost, but I’m not sure if they can actually open models generated on the commercial licence. A question to ask, I guess.

best
Simon
 

Phil O

Western Thunderer
Simon,

Is it worth trying to open one of your already created files in FreeCAD, to see if the files are compatible with that?
 

Paul_H

Western Thunderer
The wagon floor partially unstuck itself from the build plate, so is entirely scrap.
.....
There are some bits of fluff in parts, mostly where the support was, and easy to remove
It can't be overstated enough that there are two main causes of print failure in FDM printing; The build plate not being clean and the filament not being dry.
Bambu are specific NOT to use IPA to clean the build plate, but just use soap and water on their PEI plates.
I use Palmolive unperfumed hand soap, lathered up with a sponge and the plate well scrubbed, rinse and repeat, then dry with kitchen towel. In 1500hrs+ the few adhesion problems I've had have been down to being complacent and not cleaning the plate recently.

The small 'fluffy' bits sticking out are a classic example of filament not being dry enough. Even PLA straight out of the packet filament can be too wet and need drying. Other filaments are even worse. Not only will wet filament give poor surface finish, but it will also contibute to lack of plate adhesion.
A drier should be regarded as an essential accessory from day one. The cheap Sunlu ones work fine.

The next stage is uncharted territory…. I’m going to try to print buffers, coupling hook and wheels in ABS on the basis that they don’t actually need to be metal.
I'd master PLA first. Unless you need to use parts outdoors PLA is fine for just about every model part. The stronger ones like PLA+ and PLA 2 are likely to have all the strength you need without any of the difficulties of more exotic filaments.
 

simond

Western Thunderer
Thanks Paul

I suspect the lack of adhesion was directly due to thumb prints. I shall wash the plate after work tonight. That's the first lesson learned.

I have the Bambu AMS, which is also a drier - the humidity was 27% when I last looked, perhaps this is still too much. The fluffy bits in my wagon's case were mostly where it was extruding onto empty air, which never ends well!

We have two Bambus at work and we are pretty successful with them using a variety of materials including ABS. I'm not too worried about strength but stiffness and surface hardness are unlikely to be good enough for wheels and buffers with PLA.

And I discovered that the Bambu needs both print heads to be the same size - I guess in retrospect, that is blindingly obvious, but it wasn't when I ordered the extra print head on the special deal with the new printer. I shall order the second 0.2 head today, and try not to grimace too much when I have to pay an extra fiver for it. I'll have to buy some more PLA as well.
 

Paul_H

Western Thunderer
I suspect the lack of adhesion was directly due to thumb prints.
I should have added the "Never touch the build plate surface .... EVER" rule ;-)

The fluffy bits in my wagon's case were mostly where it was extruding onto empty air,
Wet filament will continue to extrude more than expected, hence the 'fluffy' bits going away from the print.
Some people go through hoops of trying to change the retraction settings to solve this, but that will lead to other issues, so it just needs to be very dry.
I tend not to trust hygrometers as they measure the surrounding air, not the actual moisture content of the filament. Ten hours in a drier solves a lot of problems.
 

John_B

Western Thunderer
My printers are in an unheated room in a 200 year old Welsh house, and I've found that running the filament drier (Sovol SV02) while printing has solved most of my printing problems in the winter.
 

Rob R

Western Thunderer
Managed to get a photo of unwanted vertical defects on my wagon prints.
Thiis one was done quite slowly (20mm/s), at higher print speeds they are less pronounced but we run into other issues.
When the current print is done I'm going to investigate the drive belts and pulleys, it is a low milage machine but that assumes that they tensioned them correctly in the first place....
3DP lines 01.jpg

MGWR open (upside down) in 1:64
 
Top