Filament Straightener

by doctek, published

Filament Straightener by doctek Jul 28, 2013
1 Share
Download All Files

Thing Apps Enabled

Order This Printed View All Apps


Liked By

View All

Give a Shout Out

If you print this Thing and display it in public proudly give attribution by printing and displaying this tag.

Print Thing Tag


Thing Statistics

10024Views 1643Downloads Found in 3D Printer Accessories


Those last few meters of filament on small-diameter rolls drive me nuts! Coiled so tightly I can barely get it off by hand, it always causes problems for my printer.

Tired of trying to uncoil and straighten those tight little loops by hand, I created this Filament Straightener. It is, obviously, modeled on wire straighteners, but uses printed parts and is sized for filament. Pictures show before and after of tightly coiled filament. The after was put back on a reel for easy printing and worked great!

This design was done using FreeCAD. As an experienced OpenSCAD user, I find FreeCAD a very satisfactory alternative that I am choosing more and more often for new designs. The FreeCAD files are included; STEP format files are also included.

This is similar to, but not derived from, http://www.thingiverse.com/thing:30733 .


Bill of Materials
One of each of the stls. I used PLA with 40% infill.
3 ea. 608 bearings.
3 ea. 5/16 x 1 1/2in.€ or M8 x 40mm bolts.
6 ea. matching washers.
3 ea. matching nuts.
6 ea. #6 x1 1/4in.€ sheet metal screws (not sure of the metric for these?).
1 ea. #10 x 2in.€, or M5 x 50mm screw (all thread if possible).
2 ea. matching bolts.
Base for mounting. I used 1/2in.€ plywood that I had on hand. Needs to be big enough to clamp or hold while filament is being straightened.

Use the straightener body as a template to mark locations of the heads of the two large bolts. Drill the holes with a diameter and depth to provide clearance for the heads. (Not critical.)

With the body in the same position, mark the groove needed for the bolt head on the slider. Allow a little extra on each side to clear the head and use a coping saw or saber saw to cut the groove. (Not critical.

Mark the holes for the four body mounting screws and drill pilot holes if needed.

Put one of the bolts through the body, put a washer on it, then a bearing, another washer, and the nut. Tighten the nut firmly.

Repeat for the other body bolt and the slider bolt.

Put the slider into the slot in the body and secure the body to your base using four of the screws.

Press a nut for the long screw into the pocket in the tensioner and thread the long screw through it.

Put the other nut on. This is a lock nut to keep the tension constant.

Position the tensioner a small distance from the body (about the width of the lock nut or so) and use the last two sheet metal screws to anchor it.

Your straightener is ready to use.

To use your straightener, put the end of the filament to be straightened between the bearings as shown in the photo. Tighten the tensioner bolt as desired, then pull the filament through. Adjust until you get the desired result. If a significant straightening is desired, often it is better to do it in a few steps using multiple passes, rather than trying to do it all at once.

More from 3D Printer Accessories

view more

All Apps

3D Print your file with 3D Hubs, the world’s largest online marketplace for 3D printing services.

App Info Launch App

Auto-magically prepare your 3D models for 3D printing. A cloud based 3D models Preparing and Healing solution for 3D Printing, MakePrintable provides features for model repairing, wall thickness...

App Info Launch App

Kiri:Moto is an integrated cloud-based slicer and tool-path generator for 3D Printing, CAM / CNC and Laser cutting. *** 3D printing mode provides model slicing and GCode output using built-in...

App Info Launch App
KiriMoto Thing App

With 3D Slash, you can edit 3d models like a stonecutter. A unique interface: as fun as a building game! The perfect tool for non-designers and children to create in 3D.

App Info Launch App

Print through a distributed network of 3D printing enthusiasts from across the US, at a fraction of the cost of the competitors. We want to change the world for the better through technology, an...

App Info Launch App

Quickly Scale, Mirror or Cut your 3D Models

App Info Launch App

3D Print a wide range of designs with Treatstock. Easy to use tools to get the perfect result. The global 3D printing network that connects you with high-quality and fast working print services nea...

App Info Launch App

I hope you're still here: how much effort would you say is needed to get the filament through this straightener? Could it be placed inline on a printer?

Thanks for your interest in the Filament Straightener!

I think your idea is possible, although it could be tricky. I've thought about this several times. The biggest problem I see is that the fiber wants to twist as it goes through the rollers. As I pull it through, I have to continually fight that tendency. Pulling it through with a gear like that used to feed the extruder should work, but I'm uncertain how to keep the fiber from twisting. If you figure it out, please post a derivative!

For myself, I think the solution is to go to 1.75mm fiber so that the curling is not as big a problem.

Good one design sir... love it as simple at it is...i will try print asap (^_^)

Comments deleted.

You, sir, are a genius, and this helped me ALOT!

Glad it was helpful, but, to quote Joe Montana, "I'm no genius. A genius is a guy like Norman Einstein."

Your straightener has made it on http://hackaday.comhackaday.com . Congrats!

Very useful! Thanks! I did have one question though; is there a reason the base isn't a single piece? Wouldn't that make for a lot less assembly and fewer screws?

Good idea. But I'm not sure how to put the slider in if the base and tensioner are one piece. What do you suggest?

Oh, I see... Ok, well, you could make the "other" end open. So you slide the slider in and then add the last two bearings. So long as the base is thick enough it should be fairly strong.

You could also turn it into a pulling setup instead of a pushing setup. Put a captured nut at the far end of the current bridge (with the bolt running through a clearance hole in the sliding block), or put a captured nut in the sliding block with a clearance hole through the current bridge. Whatever you do, it looks great though!

Excellent! Time for a derivative.