Reel Rollers with over 2KG PLA Filament Loaded

Airtripper’s Pocket Reel Rollers, named like the Wades Extruder, is a piece of kit I’ve needed for a while, and they will certainly beat hanging around the 3D printer loosening coils of filament every ten minutes. I’ve had the printer nozzle printing thin air a few times, after nodding off, forgetting to loosen the printer filament off the reel, and ending up spoiling hours worth of printing. So, if you fancy a set of these reel rollers, get the details below and get the files from Thingiverse.

Design
OpenSCAD was used to model the reel roller, and the design drivers are:

• Use the least amount of non printable hardware as possible.
• Easy to set up and put away, as working space is limited.
• Small enough to drop in a box for storage and transportation.
• To fit any size spool.
• All the parts available on Ebay.

Reel Roller 3D Printed Parts with Ball Bearings and M3 Screws

To make the reel roller compact, I decided to go with two separate set of rollers that I can put under each end of the reel, and as long as the reel can turn easily, the should stay put. However, fixing screw holes are placed in the base of the roller casing to allow for  permanent fixing if required, but I think rubber pad feet will be enough in most cases to stop the rollers from sliding on surfaces. For uneven surfaces, the rollers can be set up on a small board or a book or something.

You’ll notice from the pictures that I’m using four bearings per unit. At first, I wasn’t too keen on using so many bearings but there was obvious benefits. Using four bearings made the units wider making them less prone to tipping, and the extra bearing width will give reels with thick buckled sides more room to move freely. The bearings are cheap anyway, and commonly sold in packs of eight on Ebay.

Reel Roller OpenSCAD Model

The large bearing bores have enough room to build the ball bearing shaft in plastic as part of the reel roller casing, giving me the opportunity to use the same much lighter and cheaper bolts throughout.

Printing
The SUMPOD 3D printer, loaded with the Marlin firmware, was used for printing, in this project. The printer is fitted with a modified Mendal Parts V9 1.75mm Hot End, and sporting the new prototype extruder I’ve been working on, and the 3D printer is interfaced by the Pronterface software on the PC.

Skeinforge was used to generate the G-code from the following settings:

• Carve->Layer Thickness 0.2mm
• Dimension->Filament Diameter 1.75mm
• Speed->Feed Rate 24mm/s
• Speed->Flow Rate Setting (float) 24
• Speed->Object First Layer: all settings to 0.3
• Fill->Extra Shells on Base 3
• Fill->Extra Shells on Sparse Layer 2
• Fill->Infill Pattern: Grid Rectangular
• Fill->Infill Solidity 0.5

I set the nozzle and heated build platform temperature manually, 190 and 60 degrees respectively. I’m using PLA at these settings.

SUMPOD 3D Printer Hot End Nozzle with Bowden Tube and Fan

Parts List

1. 8 x 608 ZZ [8 x 22 x 7] Roller Skate Ball Bearings. Very cheap off Ebay.
2. 8 x M3 x 30mm Hex Head Screws. Ebay.
3. 16 x M3 washers. Ebay.
4. 8 x M3 Nuts. Ebay.
5. 3D Printer Filament.
6. Model Files from Thingiverse

Tools Required

1. 3D Printer.
2. Hex Key to Fit Screw Heads.
3. Pliers or Spanner of some type.
4. 3MM drill bit to clean out the screw holes in the printed parts.

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3D printer bowden extruder with brass insert and support ball bearing

3D printer bowden extruder with pinch roller idler

Improvement
The new 3D printer extruder works great, very pleased with the design, and now the extruder is a lot easier to work with. Changing the filament is not such a big deal anymore because now, it’s a lot easier to feed it through the mechanism and in to the bowden tube. All the extruder’s inner workings are now visible making the 3D printer extruder a lot easier to trouble shoot.

My old 3D printer bowden extruder

My new 3D printer bowden extruder

Not only is my 3D printer looking more sophisticated, it’s now 700g lighter on the back side. The most important improvement I was looking for was the extra filament pushing force. I achieved that by using a rubber pinch roller instead of a bare ball bearing, a bare ball bearing common with other extruder designs. Unlike bare ball bearings, the rubber pinch roller has a much wider contact along the filament length, forcing the filament to wrap slightly more a round the brass gear insert. This allowed the brass gear insert to have better contact with the filament which reduced slippage and improved reliability in constant extrusion rate at higher speeds. A small ball bearing has been added to the stepper motor shaft to further support the load and to help extend the stepper motor life.

Tweaking
During the the use of the new 3D printer extruder, I made a few notes to further improve the design and reliability. These improvements will be applied to the files and tested before being made available in Extruder Upgrade Part 3.

3D Printer Extruder without Idler

3D Printer Extruder Idler With Pinch Roller and Scews

• Change the in-feed filament guide hole to an in-feed guide pipe. This is to stop the filament from bending out of line and moving out of the idler’s grip. Only a problem if using a bare ball bearing but not so much of a problem if using the rubber pinch roller, since the pinch roller now has a deep grove filed in to keep the filament in line.
• Modify the out-feed bowden tube bracket so that the tube can be released without unscrewing the tube from the capture nut completely. This will help prevent spoiling the thread made on the tube by trying to screw the tube back in the capture nut, making it easier to remove and replace the bowden tube.
• Replace the M4 screws with M3 screws that hold the extruder idler in place. This will allow me to spread the screws wider apart to hold the idler more squarely. Also, the thinner screws will allow the idler to be removed without removing the screws completely.
• Widen the pinch roller bearing housing in the idler to prevent the rubber roller from scraping the walls. Build in ball bearing spacers in to the wall to keep the bearings centered in the idler housing.

The brass insert gear on the extruder stepper motor is not ideal for 3D printer extruders, but it’s cheap and easy to get hold of. I don’t have a better solution at the moment with out the high cost, so I’ll be leaving this for another day.

Design
I looked at a piece of 3mm glass that I use on my heated build platform and decided that’s a good thickness to start with in the extruder design. So, all the walls of the main body of the extruder and the stepper motor mount is 3mm thick except for the fixing plate, which is 4mm thick. To minimize the amount of plastic used and to cut printing time, I just built plastic in to the design where it was needed, I just used enough  plastic to add support and rigidity. I also put extra holes in to the design to help reduce warping during printing and to improve the overall look of the printer extruder.

OpenSCAD 3D printer bowden extruder assembly model

OpenSCAD 3D printer bowden extruder base model

The 3D printer extruder has three printable parts, the main body that attaches the stepper motor and the printer, an idler pivot support strut and the idler housing. All the parts are created with OpenSCAD 3D modeller and exported to STL to be converted to GCode by Skeinforge. The printer extruder currently under test was printed with 0.2mm layer height at 16mm/s and with hot end temperature set at 190 degree C.

Signing Off
I guess that will do for now until Part 3 of the Extruder Upgrade. Part 3 will include all the files including STL files, for those not familiar with OpenSCAD, so that you can print your own. A bill of materials will also be included which all items can be obtained from Ebay.

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3D Printer Extruder Idler Showing Rubber Pinch Roller	3D Printer Extruder Idler Parts, Ball Bearings and Rubber Roller
3D Printer Extruder Idler Parts, Rubber Pinch Roller	SUMPOD 3D Printer Extruder Idler Hack

I had planned to do a post about adding a dimmable lighting feature to the SUMPOD 3D Printer but had difficulties in extruding some of the 1.75mm filament I was using to print the lighting fixtures. I opted to buy the cheaper filament that was available around Europe which in most cases, can be less than half the price of the filament that can be sourced in the UK or America. As far as I can tell, the SUMPOD community appears to be getting better 3D printing performance out of using the more expensive filament. However, I’m not ready to give up on the cheaper filament just yet. I’m going to do some upgrading, starting with the extruder, and hopefully be able to continue using the cheaper filament with more reliability. I should point out that the SUMPOD extruder plunger modding I installed was a replacement for the plunger I lost that was delivered in the SUMPOD kit. The original plunger may have worked much better than my modded version.

Instead of just downloading a design from thingiverse.com, I decided to have a go at designing my own 3D printer extruder. For my first extruder upgrade, I’m just going to keep it as simple as possible and go for the Stepstruder style design. This design will offer improvements such as the use of a bearing instead of a plunger to reduce filament friction. Another welcome improvement will be for easier filament loading. So, without further ado, lets get started on the new 3D printer extruder.

To make it easier to design the 3D printable components of the extruder, I’m going to also include the non printable components of the extruder in to the design. This includes the stepper motor, bearings, screws and insert  which are created easily using primitive solids. Each of these non printable components will be created separately, and then added together to produce a partly completed 3D printer extruder. In part 2 of the Extruder Upgrade I will be going over the process of designing the printable component to complete the 3D printer extruder. Continue reading to learn more about the design process of the individual components and how the components are put together.

In OpenSCAD I usually start with a template to save typing and it takes the form as what you see in the image on the left. The first line starts with two forward slashes which tells the compiler not to execute this line. This is known as comment out, and usually used when adding descriptive text about lines or blocks of code. The forward slashes are commonly used to activate or deactivate modules in a OpenSCAD script. This allows you to compile only the parts of the 3D model you want to view and export. After the first line there is a block of code declared as a module. This module will only be compiled when the first line has the comment out forward slashes removed and the module name matches.
The above image represents the insert that will fit on to the stepper motor shaft to grip the filament. Only 3 lines of script is needed to be added to the template script shown earlier to create the insert. This 3D part is contained in a module called insert and it is called by using the first line in the above script. Three primitive solids are used to create the insert, the first two combined in the first union block and the third, while not required to be in a union block, is used to subtract from the first union block because both union blocks are contained in the difference block.
The above script is a bit more complicated because parametric equations are used to construct the 3D model – in this case a ball bearing. This allows me to reuse the same script to create different size ball bearing models just by passing three values when calling the bearing module. The three values required are the ball bearing measurements which include inner diameter (id), outer diameter (od) and width (w).
The Nema 17 stepper motor OpenSCAD model is shown above with the script which contains some parametric equations. The purpose of the equations are just to align primitives in relation to other primitives along the z axis. The screws in the 3D model are there as a guide while the printable part of the extruder is being designed. The OpenSCAD script will be altered once the length of the screw has been determined.The final OpenSCAD script, shown above, assembles all the different components to make a partially completed 3D printer extruder. The 3D printable components can now be designed around this assembly and having an instant view of the complete assembly at the same time. This script is a module that calls other modules for each component required for the 3D printer extruder assembly, it also positions and rotates the different components so they fit together correctly. I’ve made the OpenSCAD file available to download so that you can mess with the script yourself.

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Download Zipped OpenSCAD file: stepper_kit OpenSCAD file.

In this edition I am going to share the details of the new Z axis handle I’ve fitted on to the SUMPOD 3D Printer. I’m also going to demonstrate how easy it is to print your own Z axis handle. Although this edition is more catered for the SUMPOD owners, there are useful tips about printing tall items that any 3D Printer owner would appreciate.

I must admit, A Z axis handle was not a feature I planned to install, mainly because I did not fancy taking a hacksaw to my nicely painted printer, even if I was sticking my hand in the printer to manually turn the leadscrew. With many thanks to Mike at 3d-printer-kit.com, I now have a nice, shiny new hand made Z axis handle. Mike appreciated the work I’ve put in to Skeinforge to help him and other SUMPOD owners get their first 3D prints off the platform, and very kindly offered to make me a z axis handle.

The Z axis handle is certainly a nice feature to have, and it does help to get that last adjustment in, to get that nozzle just right above the platform during the skirt printing phase.
I would recommend any SUMPOD owner to fit a Z axis handle on their machine, and in order to support that recommendation further, I decided to see how easy it was to design and print one.

Designing the Z axis handle was done with OpenScad, which is a popular open source application used by many 3D Printer owners. This was my second attempt on the design because the first attempt failed during printing because of excessive warping, causing the print to topple over. Despite having a heated platform, the warping was not avoided. I think the warping was caused by a combination of slow printing speed and small footprint on a tall model.

I set about increasing the size of the footprint, a process quite easy in OpenScad, just by altering a few numbers in the code. In fact, a larger knob worked best for improved grip for operating the handle, and it looked better than the original design. Just to be on the safe side, I decided to add a plain around the handle to ensure stability during printing. If there is going to be any warping on the handle, the plain will keep the Z handle anchored down. Now I’m happy with the model, to increase printing speed, I decided to give the Marlin firmware a go. It took a couple of hours to set up, and made a successful test print at a much quicker pace than I could get with the Sprinter firmware, I was ready to go. Made a couple of changes in Skeinforge, because I’m using Marlin, I reduced layer time to 30 seconds under Cool and removed Z axis move from end.gcode file to avoid crushing the handle at the end of the print. I thought it was best to limit the print speed on the thin part so each layer has a chance to solidify before taking on more plastic.

The 3D print took a little under 4 hours and was a success, no warping in the handle, and the handle and plain was stuck down real good on the glass. As the heated glass platform cooled, you can hear the base of the plastic starting to dislodge itself. Soon, I was able to remove the handle from the glass bed. The plain snapped off the handle easily, leaving small notches behind. These were easily remove with a file. Putting a bit of electrician’s tape around the top of the Z leadscrew was enough to secure the handle in to position. As you can see in the picture above, the printed plastic Z axis handle and bezel look awesome!

Hope you enjoyed reading the first edition of 3D Printer Surgery. You will find more pictures and a video clip after the jump, the OpenScad and STL files for the Z Axis Handle and Bezel are available to download below.
The next edition of 3D Printer Surgery will be about lighting up the build area with dimmable L.E.D. lights.

Download OpenScad Z Handle and Bezel files

Click here to view the video on YouTube.