2019-04-25 to 2019-04-27

A project log for Poor man's Mini 3D Printer

3D Printer using upcycled CD drives, hard drives, and an ATX power supply.

AccidentalRebelAccidentalRebel 04/27/2019 at 16:124 Comments

I have narrowed down the cause of the constant hotend clogging to a loose bowden tube coupling. Because of this the tube eventually gets tugged out of place leaving a gap inside the hotend throat, which then causes a clog.

Thankfully, there's a fully printable replacement which has a better design and fits perfectly to my hotend.

Thanks to this, I've never had a clog ever again. I do need to double check if it's tight from time to time. Also, I'm a bit worried if the heat from the heatsink would affect the coupling since I printed it with PLA. We"ll see if it gives.

Another improvement that I made is I added springs to the screws that I use to level the bed. The spring is always pushing on the bed which makes leveling easier as I only need to adjust the top screws.

With the setup before I had a top screw and a bottom screw, which I both need to adjust when leveling. It's now easier to do last minute micro adjustments thanks to this.
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After this I went nuts with printing.

However, I have limited options of what to print from Thingiverse because of my small printbed. I can scale down most of them but not everything can be.

I've played around with Tinkercad too to make my own designs and sometimes to modify existing ones to fit my needs. It's not as powerful as other 3d apps I've tried before but it works fine for my needs.

Up next: More printing, printer improvements, and fine tuning!


Daren Schwenke wrote 04/28/2019 at 01:43 point

That is a pretty good bed support strategy.  I've used variations on that with every 'from scratch' printer I've built.  If you have the stiffness, supporting it at 3 points simplifies things a bit.

As for the PTFE tube migrating and leaving a gap in the hotend..  You can totally solve this issue with the standard fittings, probably better than what you came up with.  Not that I don't appreciate that...  :)

Loosen the existing fitting about 3 threads.  Shove the PTFE in to that depth (fresh PTFE section so you don't have cuts/ridges on the OD)  Pull up on the release collar to make sure the grip is engaged, then pull back on the tubing, hard.  The fitting will dig in and permanently set a depth, but in the process it will retract about 1mm.  

Insert some filament.  This keeps the intersection centered and somewhat prevents compression of the end. Tighten the fitting back up.  If you experience resistance, unthread it all the way and cut a tiny slice off the end of the PTFE.  Do not pull the PTFE back out...  :)

It won't slip out again.

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AccidentalRebel wrote 04/29/2019 at 00:43 point

Hi Daren. I should try your suggestions with the standard fittings. It's a cheap knockoff so I was quick to find a replacement for it. I'll give it another chance next time, maybe I really was just using it incorrectly. Thanks!

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Daren Schwenke wrote 04/29/2019 at 01:00 point

From what I gathered, it's just the nature of these types of fittings.  They don't grip really well until you give them a tug, but in doing so they retract out a little.  Fine for hydraulic purposes, not so much for this.  This pattern just compensates for that retraction.  When you need to remove that end, just unscrew it instead of releasing the PTFE.

Excessive movement right where it goes into the fitting can also cause the PTFE to deform and migrate.  If it has to move there, wrap it in some heat shrink and/or put a spring over it to spread out the bending.

Good luck with your project.  Most of my earlier projects came down to 'so what can I make out of this'.  I love it.  :)

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AccidentalRebel wrote 04/29/2019 at 06:38 point

Oh nice. I have been having problems with the PTFE deforming. Your tip about adding heats shrink might definitely help with that. Been finding more and more uses for heatshrink lately.

Thank you for wishing me luck. This project has definitely opened up more ideas for me to try in the future ;)

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