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All,

I made a 1/4-20 bolt in solidworks just to see what would happen if I tried to print one out.

The first one was terrible. I was using a ton of infill, and the threads were just a blob.

The second one, with the infill set to 0.2 was much better in terms of the screw helix not being a big blob of plastic. While it looked generally better, the screw thread was very bulbous and rounded. It was easy enough, however to fit into a 1/4-20 die and clean up. I would rather not have to do that, though.

So my question is: is anyone printing screw threads with standard geometry that are clean right off of the printer? Am I asking too much to print one as small as 0.25"? How about 3/8 or 1/2" threads?

Any tips or tricks?

I'm using ABS BTW.

Thanks,
Darren

I print threaded parts pretty often. I use S3D and sometimes add a second process when it comes time to print the threads...I slow it down. Most of the time the threads come out just fine but sometimes I'll just run a nut up and down the thread a few times after printing just the clean up the threads a bit.

A lot of the stuff I do is cylindrical and threaded. I recommend using a tiny nozzle (0.25mm) for threads, especially if they have high overhang angles, like acme. I've gone as small as M6 6mm threads with a small nozzle. Make sure you go slow, and nylon works the best by far. Under-extruding slightly will help your print quality too.

Here's one I did last August, its a model of a nozzle.

[img]http://forum.seemecnc.com/download/file.php?id=5991[/img]

I figured the nozzle is a little too big for this type of work. It's nice to know that a smaller nozzle will tighten it up a bit. It would probably work for larger diameter screws.

I didn't get the machine to do this; I'm just interested to know its limitations.

Darren

I actually designed a rather interesting (I think) hyperbolic worm gear. It has some weird overhangs with PLA, but I'm sure printing with something like Nylon would make it easier, but mine print ok and are fully functional. Here's a screenshot of me working on it in AutoCAD.

Here's one I just printed this morning. 12mm-1.0 tapered thread x 9.5mm barb. Threads look a little rough in the picture but screwed in perfectly to the metal female thread. ABS and sliced with S3D.

heathenx wrote:Here's one I just printed this morning. 12mm-1.0 tapered thread x 9.5mm barb. Threads look a little rough in the picture but screwed in perfectly to the metal female thread. ABS and sliced with S3D.

Nicely done. What is your layer height? Minimum layer time?

My layer height on that one was .17mm and printed at 30mm/s with the cooling fan (PLA) set to 50%.

That's nice work. Just to clarify: you're printing in ABS, and you're using the layer fan?

Thanks,
Darren

dmcmd wrote:That's nice work. Just to clarify: you're printing in ABS, and you're using the layer fan?

Thanks,
Darren

Ha! Yup! Normally I never do that but on small parts like this it's sometimes beneficial to turn the layer fan on. You'll need good bed adhesion of course (I used hairspray on this job). I only had the fan set to 50% and I ran the job at 30mm/s. Nice and slow. An alternative to the layer fan would be to print two or three models instead of one. That would give each layer on each part time to cool before the next bead gets laid down. Keep the part close to minimize any stringing if that's an issue. We all have our tricks, right?

That is very nice! What temp did you use for the ABS when using the layer cooling fans? I have been testing various temps, speeds and fan settings for ABS and have not had good results (e.g. getting good adhesion or print quality) when I turn the fans on.

Thanks

-jeff

I print ABS at 230°C and run by bed at 85-90°C.

jwalrath wrote:That is very nice! What temp did you use for the ABS when using the layer cooling fans? I have been testing various temps, speeds and fan settings for ABS and have not had good results (e.g. getting good adhesion or print quality) when I turn the fans on.

Thanks

-jeff

Don't use fans with abs.

JFettig,

Typically I dont use fans with ABS as per most people's advice. But I have seen several people mention using fans and when I saw his print with the screw I was curious what temps he used with the fans to see if I could reproduce. Just a curiousity thing really. Several people here claim to use fans with ABS and insist on always using fans WITH ABS so I am trying to see what the benefit is. I have not been able to get a decent print with the fans so wondering how heathenX did so well.

-jeff

I have seen no one insist on using fans with ABS at all times. ABS and fans are very situational, mainly with small parts/features where the hotend would mess up the part from the time it spends there. This is a rarity, and fans mixed with ABS is generally regarded as an "advanced" strategy.

Absolutely I would agree with Nylocke. I never use fans as my slicer has options to slow down the print speed in situations where others use fans.

In 99% of the cases of printing ABS, fans will give poor results compared to no fans. Heathenx used a fan with PLA - which is typically required.

heathenx wrote:My layer height on that one was .17mm and printed at 30mm/s with the cooling fan (PLA) set to 50%.

I don't even have provisions to mount fans to my machine anymore.

I use Cura to automatically scale the fans according to the layer time. And yes I use it on ABS. What can I say, I like to print fast!

For ABS my minimum layer time is 5s, minimum speed 5mm/s, fan min 0%, max 100%. This means that the fans will just start to turn on when the layer time is 5s. It will scale the fan up to 100% at a calculated layer time of 2.5s, but it will slow the print down so that it's still 5s layer time. Below calculated 2.5s layer time it will keep the fan at 100% and try to keep the layer time at 5s, but it will never go slower than 5mm/s.

That is something I might try out rpress, once I get my TL arms installed, having a warm enclosure might make a layer fan have less detriment to ABS if the air isn't real cold.

heathenx wrote:Here's one I just printed this morning. 12mm-1.0 tapered thread x 9.5mm barb. Threads look a little rough in the picture but screwed in perfectly to the metal female thread. ABS and sliced with S3D.

Do you mind sharing that barb file?! I need one just like it.

I've made the Makerbot Nut & Bolt a few times on different machines as a calibration test. You will want to enlarge the "nut" by about 5-10% to make it work well.