Need suggestion on making a nice and big case

[forever9801]

Dear M2 fellows,

I think I'll start this post by introducing myself a bit and then to the problem that I'm facing right now. I work in a company and have bought 2 M2s for about 6 months, and is generally happy with them. I followed the forum occasionally (stealthily!), and made several modifications to the printers. I've build a large enclosure for the M2s (and they cost a fortune), added the motor dampers (this really takes out about 95% of the motor noise), tried the zebra plate and now the PEI bed.

The enclosure

Since I hope to produce some small quantity components for our commercial product using the M2s, the surface finishing actually matters. So I have been thinking using ABS with acetone vapor treatment. So far it seemed promising, but kept failing on the biggest and the most challenging component - the product case. Although I could stop the corners from warping, there will always be cracks on some distance above the bed. And they seemed worsen after the acetone treatment (1 crack became 5, for example).

Case with crack (after acetone treatment)

Case with crack 2

And I dont know why my PEI seemed to be more "sticky" that those read on the forum. It runs on lower temperature and still take a lot of effort to remove parts. :/ (I guess it's because of the spacing...?) Well but that kept the case corner from lifting, and the warping force is so strong that the case even cracked the glass underneath the PEI in half, lol. And I've also tried PETG, thinking that I might have to sand-blast it later if it succeeds, but end up breaking 2 glasses in a row (I tried printing it on the PEI but it stuck too well that I had to sand the PEI twice to remove residual parts, so I lost patience and went with the glass).

Broken glass

Glass shards on part

So I'm now out of glasses. I've ordered a rolled AL plate (Well I cant acquire any MIC6 plate easily, and it seemed to have better tolerance than the MIC6) for testing it with PEI. Considering order more boros (Is it the same as Pyrex?). Some tricks that haven't been tried: add heater and temperature control to the enclosure (it went to as low as 10 deg Celsius recently), try thicker case... okay I'm lost.

It is appreciated if anyone has any suggestion on how to make a nice finishing case, or anything else.

Thanks in advance!

[insta]

I can be more helpful later, but I'm about to have a bunch of boro sheets available (5-6) if you're interested.

[forever9801]

Thanks insta, but as I don't live in the state, the shipping cost might be a problem. I'll just look for a local source.

[Kulturfolger]

Hi,

Borosilicate Glass Sheets are used for fireplace windows. I buy the glas from a fireplace supply store. If you have to use ABS its okay to use it. Borosilicate Glass Sheet breaks when you apply point pressure. How do you remove prints? Usually a sharp tool damages the glass and the next print removes parts of the glass. Take a look at this post: http://richrap.blogspot.de/2016/02/glas ... e-not.html

The box you are printing is easy to print with PLA and PET-G but pain with ABS. Its all about the shrinking process. You need a fully enclosed printer with an actively heated build environment ( up to 70°C / 158 °F) which is not possible with the makergear. The printer you are looking for preheats the build chamber and uses water cooled extruders and steppers.

On the other hand either your ABS material is bad (black ABS is usually the thrash-bin, go for transparent filament) and your temperature is to low. When you do the acetone treatment and the layers delaminate they did not bond well enough. The stress is very high inside the material. Even when the print is okay, it will crack over time.

Ingo

[forever9801]

Hi,

Borosilicate Glass Sheets are used for fireplace windows. I buy the glas from a fireplace supply store. If you have to use ABS its okay to use it. Borosilicate Glass Sheet breaks when you apply point pressure. How do you remove prints? Usually a sharp tool damages the glass and the next print removes parts of the glass. Take a look at this post: http://richrap.blogspot.de/2016/02/glas ... e-not.html

The box you are printing is easy to print with PLA and PET-G but pain with ABS. Its all about the shrinking process. You need a fully enclosed printer with an actively heated build environment ( up to 70°C / 158 °F) which is not possible with the makergear. The printer you are looking for preheats the build chamber and uses water cooled extruders and steppers.

On the other hand either your ABS material is bad (black ABS is usually the thrash-bin, go for transparent filament) and your temperature is to low. When you do the acetone treatment and the layers delaminate they did not bond well enough. The stress is very high inside the material. Even when the print is okay, it will crack over time.

Ingo

Well on the PETG case, the glass was broken spontaneously when it cooled down and PETG parts broke contact with it. No human force was involved . It just somehow bit large pieces of glasses with it in the process, twice.

And yes I do understand the shrinking concept. In fact we printed the case several times in PLA for prototyping. It's just that we need a more "finished" surface or at least something that the customer will not feel that the case is "cheap". We hope to use ABS because of the possibility of vapor treatment. (but I did find that beside printing the case, it is difficult to vapor treating the whole case uniformly. Probably because I'm doing it in the cold way?) The next of choice would be PETG, and with some sort of surface finishing process. If anyone have any idea on how to make PETG parts look nice, I'm all ears.

BTW, the color is actually silver blue (or at least what was written on the box cover). Did you refer to extruder temperature or bed temperature? I have been using 245-250oC for extruder, 80-90 on PEI presently (and they stuck on the bed real hard). And thanks for the vapor treatment info, although I did find that out in the hard way I thought the melted surface would create a stronger bonding for the part, but it seemed that it cannot withstand the inner stress and self-exploded before that happens.

[Kulturfolger]

Well its not that easy. It took me ten different ABS suppliers to get the stuff I wanted. Try a thick PEI-coated-aluminium-print bed. with thick I mean 5mm. Heat the chamber and replace all fans with water cooling. Same for the steppers.

Ingo

[Jules]

....... If anyone have any idea on how to make PETG parts look nice, I'm all ears.

Smooth-On XTC-3D epoxy. It gives a beautiful, glassy finish that completely fills all of the layer marks. Jin has got some spectacular examples of it's use........

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viewtopic.php?f=6&t=2447

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[jsc]

Yes, XTC-3D works well for many things. I think you could probably use any thin epoxy, I'm not sure Smooth-On has magic secret sauce for 3D printing. I've also had decent success with just a thick layer of high-build primer, but that is obviously a little more fragile.

[Kulturfolger]

I think the Smooth-On guys are passing off old ideas as new. Generic "fiberglass resin" from your local home depot will create the same result. Its possible to use hot air to welt filament into gaps. Large flat areas = body filler and sanding. Finer details remain better visible with the resin. Look here: http://imgur.com/a/pTKqM

[ednisley]

any suggestion on how to make a nice finishing case

Looking back over your pictures, perhaps a 3D printer isn't the right way to build those big flat panels.

Fused-filament manufacturing has many "things not to like":

• Lousy surface finish
• Painfully slow throughput
• Limited choice of materials / colors
• Poor mechanical properties
• Small build volume

Maybe combining laser-cut panels with 3D printed features / mounts / corners / brackets would get you closer to your goal. You'd get a much better case appearance and cutout shape flexibility, plus the ability to redefine the interior features without having to build another whole case in one shot.

You'd put about the same amount of labor into each case, but the results wouldn't depend on how good your folks are at slobbering epoxy over the surface and waving a spray gun around the case. Most of the labor would go toward gluing 3D printed features onto alignment pins inside the case, where nobody cares about a little solvent making its way out of the joint.

When you find yourself locked into a steel-cage death match with your production process, that's a broad hint that you're applying the wrong hammer to the job...