Open source 3D printed mining frame for Biostar TB250-BTC D+, hackable - based on 20x20 aluminum extrusion profiles.

18 Sep

Open source 3D printed mining frame for Biostar TB250-BTC D+, hackable - based on 20x20 aluminum extrusion profiles.

Biostar TB250-BTC D+ is riser-less motherboard for 8 GPUs, similar construction to well known Octominer or Onda motherboards. It enables you to create very small rigs for 8 GPUs. One of biggest advantage is that that you can use server PSU to power it.
Since we love riser-less motherboard idea so much we've decided to provide open source frame for this motherboard.

Size Matters

Smallest 8 cards rig ever - just 54x36x17,5cm. Best for small mining farms or if you have little space for it.
In comparison with standard 6 card rig which is about 55x30x45cm it's tiny.

Functionality of open source mining rig

  • One mount for server PSU, screw-less.
  • One mount for ATX PSU, screws needed.
  • Positioning vertically or horizontally - you can mount foots on side or at the bottom.
  • Easil mounting of fans as many and as big as you pleased - we've used six 120mm fans (two pairs of three fans - top and side). It's recommended to use faster fans since cards are really close together, we've used 12V*0,3A fans, they are quite loud but doing ventilation properly.


Parts needed

Caution: in order to easier distinct parts we will use purple bold text for all parts that you need to buy and green bold text for all 3D printed parts

So in order to build this frame you'll need to buy those parts:

  • 5 * 50cm 20x20 extrusion aluminum profile
  • 4 * 30cm 20x20 extrusion aluminum profile
  • 4 * 11,9cm 20x20 extrusion aluminum profile

Total: 417,6cm - 20x20 extrusion aluminum profile (you can buy those here)

Bolts and caps you ned to buy:

  • 24 * M6x25 bolts - used to join extrusion aluminum profiles, it has to be flat head version, recommended allen (hex) head
  • 40 * M5x10 bolts - used to mount cards, corner connectors, mount ATX PSU, mount fans, better if you have them little more just in case, 40 is minimum, you can use them more if you construct it differently
  • 24 * M5 thin caps - standard caps are to tall, so you have to buy small
  • 4 * M3x10 bolts (probably you got them with ATX PSU)

Parts you need to 3D print yourself:

Optional 3d printed parts:

  • 4 * asymmetrical 2020 foots (download)
  • N * cable clips
  • N * 120mm fan connector (download)

All parts can be printed without supports so they are easy prints.
For printing use PETG or ABS because of high temperatures. We've used PETG and it's working without problems.
Do not use PLA 3D printed parts for mining.

** - optionally you can print and use more brackets but rig is very stiff only with 4 of those

Here you can see all 3D printed parts used in this project:


  • lime -  M5 T nuts
  • gray - corner flat connectors
  • pink - 3 way corrners
  • orange - server mounts & top
  • red - rig's foot
  • purple - motherboard mounts
  • green - ssd mounts

This is how you assembly 2020 extrusion and M5 T nuts or it's metal alternative, just slide it in:


To assebly this rig you need to join partrs in corect order, without this you'll end up rescrewing everything few times, trust us ;-)
First: electric screwdriver is a 'must have'.

  1. Begin with tapping extrusion profiles ends. You'll need to tap them before screwing the rig. Tap all extrusion profiles on both sides with M6x25 bolts.
  2. Slide six of 20x20 motherboard mount on one longest (50cm) aluminum profile.
  3. Slide two of 20x20 motherboard mount on one longest (50cm) aluminum profile than slide one 20x20 small ssd mount, than another one motherboard mount, second ssd mount and last 3 motherboard mounts. So you will have SSD mounts between motherboard mounts, mounted this way:
    Motherboard and SSD mount 20x20 extrusion profile

  4. Put those long profiles flat and lay motherboard on them to adjust mount positions to fit motherboard holes.
    You'll end up with result like this:

  5. Next step it to slide 20x20 PSU ATX distance strait on one 30cm side aluminum extrusion. Don't worry about specific position - you'll adjust it later. Also slide in 1*M5 T nut at top of this side:

  6. On the other side 30cm aluminum profile slide in 1*M5 T nut at top of this side as well:

  7. At bottom longest extrusion profile slide in:
    1. From the bottom side two asymmetrical 20x20 stabilization foots - directed outside,
    2. On side one 20x20 ATX PSU distance - directed inside,
    3. On top four 20x20 fan mounts - you can use different setup.

Continue reading part 2.


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