K’s MINI Enclosure

An Enclosure for Prusa MINI

K’s-MINI-Enclosure by Stefan Katerkamp / CC BY

V0.81 / 30.01.2020

K MINI Enclosure

This is a modular enclosure for the Prusa MINI. It is based on 20mm x 20mm Type-I (5mm slot) aluminum extrusions and quite a few DIY 3D printed parts such as quickrelase locks, feet, handles and brackets. Some additional parts like screws, Polycarbonate and PVC foam sheets make it complete.

Maximum temperature of the chamber should not exceed 40°C. Precautions have to be taken to prevent the air from getting hotter, building a temperature controller is the next step. Electronics and power supply are located outside of the chamber. There are DIN rail mounts on the bottom of the frame.

3D printable part files (STL) and their FreeCAD sources are available on Github.

This is work in progress. I’ll keep updating this page and the git repository as I am getting along with this project. See project status section below.

Impressions

Access to buddy board stays outside of chamber:

kme 20200129 ps+ctrlr detail.1600

There is sufficient real estate available for a Raspberry Pi (heat chamber control etc.) and a 5V power supply. Shoes on this pictures are still the old version, the new shoes are 1/3rd shorter:

Frame Powerbrick+DINrails

Display:

kme 20200129 disp detail.800

Quickrelease locks for panels:

Quickrelease Details

Advantages

  • Smallest size possible: 40cm x 45cm (54cm incl. handles) x 49cm (Width x Height x Depth).

  • Perfect access to print bed due to large front door opening on corner.

  • Easy access to printer by using quicklocks for panels.

  • Electronics stays outside of chamber, air temperature limited by stepper motors and 3DP parts of printer only.

  • DIN Rail mount for power supply and chamber air controller

  • Cost efficient, needs slightly less than 6m of cheap No-Name extrusion (Extrusions are manufactured in lengths of 6m).

  • Cost efficient blind joints used.

  • DIY tapping possible using M5 Tapping bit and cordless screwdriver, 3DP tapping guide tool included in repo.

  • Hex wrench access holes DIY friendly, need 3.5mm drill and drill rig.

  • M5x16 BHCS screws and panels available in DIY stores

  • 3DP center plates for blind joints are sufficient

Current Status (30.01.2020)

Prototype assembled, all fits fine. MINI mounting brackets will be redesigned as foam rubber is needed to prevent noise. Vertical beams now have 380mm length.

For symmetry reasons a beam has been added on the rear side of the handles.

Drawings are not up to date yet. Check FreeCAD sources for accurate dimensions.

Aluminum Extrusions (20x20 Slot5) Frame: OK

The beam layout, sizes and positions are fine so far. See BOM below. Slightly less than 6 meters are needed.

Feet (3DP): OK

There is sufficient height available now to mount powersupply and other components on DIN Rails in the bottom area.

Powerbrick Shoes (3DP): OK

New version now has 10mm less depth compared to the ones on the prototype. Mounting holes for either APRA low profile or DRG-01 Aliexpress DIN Rail brackes have been added.

DIN Rail Holders (3DP): OK

They need M5x8mm BHCS screws. There are 2 holes for M2x15 or M2x20 screws on the back side. These are optional and used for reinforcment only.

Prusa MINI mounting brackets (3DP):

Brackets fit fine. However, there is no sufficient acoustic isolation. New brackets are coming soon. They’ll also be simpler to install. No changes to aluminum frame required.

Bottom enclosure panels: OK

PVC foam sheets with a thickness of 3mm are used.

Walls (3DP): OK

These walls keep the bottom panel in place.

Top Handles (3DP):

Need to be a bit wider to fit additional beam.

Quickrelease Parts (3DP): OK

FreeCAD source has a parameter for panel thickness. STLs for 2, 3 and 4mm are provided. Print with ABS or ASA. Slice mesh part with 50% infill, 7 layers and 5 perimeters.

Covers (Polycarbonate 2mm) and Front Doors (4mm):

Detailed shapes and sizes still have to be documented.

Enclosure Assembly

Frame

The frame is built using 20mm x 20mm Type-I (5mm slot) aluminum extrusions.

Extrusions (1 is missing on the pic):

frame parts

Extrusions assembled (1 missing):

frame assembled

Blind Joints

Blind joints are cheap, simple and stable joints:

20x20 5mmSlot blindJoint

They just need a round head hex M5x20 screw and a centerplate. Here is a 3D printed one:

centerplate 3dp
20x20 5mmSlot blindjoint 3dp

For improved stiffness, metal ones may be used:

5mmProfile Centerplate

The prototype has been built with 3D printed center plates. This saves about 7 €.

One side need a 3.5mm hole for the hex wrench, the other extrusion needs to be tapped. A guide for the tapping tool is available in the tools directory for 3D print.

3D Printed Parts

Use ASA or ABS. Slice with at least 50% infill, 5 perimeters and 7 layers. Use 0.15mm layer height.

BOM

Extrusions

Extrusions need to be cut in length, for blind joint they need holes and threads according to the abbreviations below.

M5x20 inner thread on front side:

LTP

Left front side tap

RTP

Right front side tap

TPW

Tap on both front sides

3.5mm diameter wrench access hole for blind joints on edges:

LCH

Left side horizontal

LCV

Left side vertical

RCH

Right side horizontal

RCV

Right side vertical

3.5mm diameter wrench access hole with distance from side:

LSHxx

xx mm from left side horizontal

LSVxx

xx mm from left side vertical

Qty

L [mm]

Position

Machining

1

435

T-Y-Left

TPW-LSH165-RSH125

1

435

B-Y-Left

TPW-LSH85-RSH135

1

435

B-Y-Middle

TPW-LSH85-RSH135-LSH165

4

370

V-FL, V-BL, V-BR. V-FR

LCH-LCV-RCH-RCV

2

340

T-X-Middle, B-X-Back

TPW-RSH110

2

340

T-X-Handle, T-X-Back

TPW

1

260

B-Y-Right

TPW

1

260

T-Y-Right

TPW-RSH125

2

240

T-X-Front, B-X-Front

LTP-RCH

2

220

B-Carrier-F, B-Carrier-B

TPW

1

155

T-Y-Middle

TPW

1

100

B-X-Right

TPW

Polycarbonate Sheets

t.b.d.

What’s next

Other things to add/todo:

  • Fan and controller for enclosure

  • LED Stripes for lighting

  • Camera for Printbed

  • Camera for Spool

  • Bracket for Raspberry Pi and 5V power supply