The "Full Extension, Rack and Pinion, Linear Rail" drawer, or FuExRaPiLiRa for short (it was originally going to be called FLDSMDFR, but that was taken - what are the odds!?).
It's a drawer system that prevents the drawer from being fully removed, but it can still be fully pulled out of the cabinet - because of a telescoping linear rail mechanism. This makes it act like a rail mechanism, similar to a toolbox or file cabinet, but the rails are fully 3D printed instead of being made from folded metal and using ball bearings. Note that although the linear rails are fully 3D printed, this project does use quite a few M3 screws.
See video for instructions and demo, https://youtu.be/yQ_wK-fXBsk
DIFFICULTY WARNING
THIS THING WILL PROBABLY BE TOO FRUSTRATING FOR MOST PEOPLE TO ASSEMBLE! Not a dig on anyone's assembly skills, it's just,... a lot. Before deciding to print a drawer (or a cabinet with multiple drawers), I recommend trying to print and assemble a single rail to see if you want to invest more filament and sign up for the rest of the assembly process.
The original linear rails (and pinion gearballs) are twice as big, and way easier to assemble, but I scaled them down to get that toy-boutique-container aesthetic, which makes the parts really challenging to work with.
Parts
- M3-8 countersunk flathead screws
- M3-12 countersunk flathead M3 screws
- x2 per drawer (technically, per-drawer-handle)
- M3 square nut
- x2 per drawer (technically, per-drawer-handle)
- M3-10 Socket head cap screws
- M3 hex nut
The countersunk screws can be any drive - I've used slotted, Phillips, and hex without issues, but I've noticed the screw heads can vary a little bit, and some of the larger radii don't perfectly fit in the sockets.
Also, unlike most other screw types, where the screw length is measured by the length of the (threaded) shaft, flathead countersunk screws are typically measured from the very top to the very bottom of the screw. The measurements mentioned also go by that convention. I've also seen (and bought) flat countersunk screws that were sold by shaft length; from what I understand, they shouldn't be doing that because it goes against the standard. If that's the case, add 2 mm to the advertised length.
Tools
- Sharp blade
- Screwdriver for the countersunk screws
- Screwdriver for the M3 socket head cap screws
- Pliers to seat the hex nuts, I recommend parallel pliers.
Printing
All model files should already be in the correct orientation, with the correct side facing up on the print bed. No supports are needed, but some models print best with a 5mm brim; the parts description will mention if a brim is recommended. PLA and PETG have been tested to work well.
Make sure your parts do not warp on the print bed, especially the gears and parts for the linear rails. The rack and pinion gearing is pretty small and pretty much at the limit of what's sane for consumer-grade FDM printing. Any warping that's visually noticeable will make the parts unusable, or, for the very least, make the gear placement during assembly more of a nightmare than it already is.
Drawers
There are two different drawer sizes:
- Small - the standard type of drawer.
- Medium - About 1.5x the height of small drawers.
There is no "Large" drawer, or any plans for one to be included, mainly because I can't support the extra permutations that would involve.
Each drawer requires a handle and two fully assembled rails.
Drawer_Handle.stl- x1 per drawer
- 5mm brim recommended.
Rails
For one rail:
Rail_Inner.stlRail_Middle.stlRail_Outer.stlGear.stl- x8
- In the instructions, they may sometimes be referred to as "pinions" or "gearballs"
- 5mm brim recommended.
Cabinets
5mm brim recommended for *_Housing.stl and "*_FrontCap.stl.
Cabinets are made of 3 parts: a backplate, a housing, and a front cap. Several cabinet variations are included that require different quantities and sizes of drawers. They will have a filename formay of <grid_width>x<grid_height>_<sizes>_<Backplate|FrontCap|Housing>.stl.
There are some "TopAttach" versions of the Backplay and FrontCap. These are meant for wood screws to fasten the cabinets underneath a surface like a table or shelf. While these designs are included, they have not been tested.
- grid_height
- The number of drawers arrayed vertically.
- grid_weight
- The number of drawers arrayed horizontally.
- sizes
- One or more letters, S and M. S for a small drawer, and M for a medium drawer.
- The sizes of each of the drawers in the grid, going from left to right for each row, and then top to bottom.
- For example, if we have
2x2_SSMM_* (not actually a version that's included, but makes it easier to explain)- There are two columns and 2 rows, so there should be 4 numbers (2*2).
- The first letter is the top left drawer size, small.
- The second letter is the top right drawer size, small.
- The third letter is the top right drawer size, medium.
- The fourth letter is the bottom right drawer size, medium.
Pick a drawer size, and print a backplate, front cap, and housing. This will determine how many drawers you will need to print, and what size drawers should be printed. And that will determine how many rails, handles, and screws you will need.
WARNING: CABINETS WITH MORE THAN ONE COLUMN MAY BE DIFFICULT TO ASSEMBLE, BECAUSE THE DRAWERS CAN BLOCK ACCESS TO SCREWS OF OTHER HORIZONTAL NEIGHBORING DRAWERS.
Assembly
These assembly instructions will assume a 1x1 drawer is being printed. It should be easy enough to adapt the instructions for larger grids.
See the project video for assembly demonstration.
Handles
If you are building a cabinet that has multiple columns, you may want to install the handles at the end.
- Remove the brim for the handle.
- The handles have 2 slots, one on each side, for square nuts. Push square nuts into them. Make sure they're pushed all the way in.
- The bottom of the handles has diagonal cuts. Place the handle next to the front of the drawer, where there will be a matching section where the handle should fit. Ensure the bottom of the handle aligns with the bottom of the drawer.
- Using force, push the handle's bottom into the top of the area it should fit in the drawer.
- Place M3-12 countersunk screws in both ends.
Linear Rails
Instructions will be for a single rail. Two rails are needed per drawer.
- Remove the brim for the gears.
- The inner rail bores may have some filament drooping from the overhang. Clear out any burs and ensure the bores are clear.
- Take the inner and middle rail parts. Ensure the arrows on both parts are facing the same direction, and place the inner rail into the middle rail.
- Move the inner rail in the direction opposite to the arrow, so that the line in front of the arrow lines up with the edge of the middle rail.
- On the inner rail, where it meets the edge of the middle rail, place a gear on each side. Press them a little bit so the gearing will hold them in place. MAKE SURE THE GEARS ARE PLACED IN THE CORRECT DIRECTION SO THEY PROPERLY MESH WITH THE RACK TEETH ON THE RAILS.
- On the inner rail, on the edge inside the middle rail, place 2 more teeth. This can be difficult to juggle all 4 gears being on the edges and not falling out. If you're able to, you can also place the gears to be more meshed, deeper in the rack and pinion system during assembly of the gears, and pull/push them to the edge after all the gears are held in more securely. Earlier, when it was mentioned that assembly is difficult, THIS is the step that makes it difficult.
- The middle rail will have arrows on the edges that point in the same direction as all the other arrows. In front of those arrows is a transition from the raised surface to a groove. The location of this groove will match up to where the alignment reference was on the inner rail.
- Place the middle rail into the outer rail; ensure the arrows on both parts are facing the same direction.
- Move the middle rail in the direction opposite to the arrow, so that the line in front of the arrow lines up with the edge of the outer rail.
- Add 4 more gears to mesh the middle and outer rails, similar to how it was done for the inner and middle rails.
When fully assembled, you can push the rail parts in the direction of the arrow to telescope the rail. The rails should have stoppers that will prevent the telescoping action from overextending. When pushing the rails backwards, make sure the gears don't slip out. Until the rails are installed in the cabinet and the cabinet's backplate is installed, nothing (except you being careful) prevents the rails from moving too far back.
Cabinets
- Remove the brim for the
*_Housing and *_FrontCap prints. - Follow instructions for Linear Rails to make 2 linear rails (for every drawer in the cabinet).
- On the drawer, there are 4 hex nut seats. Place hex nuts in them and press them in with the pliers.
- On the inside of the cabinet, there are 4 hex nut seats. Place hex nuts in them and press them with the pliers.
- On one end of the housing, there is an opening where the rails can slide in. Slide in both rail subassemblies, ensuring the arrows point forward (towards the sliding direction).
- Fully telescope the linear rails.
- Fit the Backplate on the housing on the end that the linear rails do not extend out of.
- Place M3-8 countersunk screws in the backplate to fasten it to the housing. After this, your rails should now be guarded from extending backwards.
- Fit the Front cap on the housing on the end that the linear rails extend out from. The rails should be going through the hole in the middle of the cap.
- Place M3-8 countersunk screws in the front cap to fasten it to the housing.
- Place the drawer between the rails, with the handle pointing towards the front.
- Note that on the side of the middle rail, there are cutouts that provide access to the screw bores on the back of the inner rails.
- Take 4 M3-10 screws and thread them so they fasten the inner rails to the drawer. For the back screws, place them through the cutouts on the middle rails.
- Ensure screws are threaded deep enough that they will not interfere with the middle rail when untelescoped.
- Basic assembly is complete. If the drawer is very firm when telescoping, it can be exercised to slightly loosen the drawer. The drawer may also loosen over time with use.
Exercising Drawer Rails
- Fully extend the drawer.
- Firmly push the drawer in a direction that's not in-out (not the telescoping direction of the rails)
- Firmly open and close the drawer all the way several times. The more force you use, the better the chance of loosening the rails. DO NOT USE SO MUCH FORCE THAT THE GEARS SKIP - IF THIS HAPPENS, IT WILL REQUIRE DISSASSEMBLING THE CABINET AND RAILS TO GET ACCESS TO REASSEMBLE THE GEARS.
- Choose another direction and repeat.
- Repeat for 8 directions: Up, Down, Left, Right, and the 4 diagonal combinations (up-left, down-left, etc).
Safety Warning
A blade is recommended to smooth out the areas with a brim. Be careful with the blade (I'm sure we all know that, and it didn't need to be said, but I'm just saying it to say that I said it).
When the drawer is fully extended outwards, it has a lot of leverage to tip over the entire cabinet and spill its contents, especially if the rest of the cabinet isn't weighted down. To avoid tipping, consider fastening the cabinet to a surface - I've been using 3M Command strips.
Source File
Blender source file is included, but it's not designed to be readable for others. I will not be giving support for it.