Quite some time ago, I have bought one of Skarsta tables. As its electric alternative Bekant seemed to me overpriced and it doesn't have many preset_values for custom positions. Design of the case and its mechanical parts (mainly motor and encoder) was updated multiple times during this time. First version was powered by FIXA Screwdriver. This was great, as I was reusing all of its electronics. However, it has drawbacks, as it could not handle heavier loads of stuff on the table and PSU that was supplied, could be used only for recharging, which resulted to dead batteries sooner than expected. After testing quite a few DC motors from Ebay, Aliexpress and Banggood, I stuck with DC-12V-180RPM Motor, that satisfies my needs at the moment. But basically, you can use any motor that you have... All you have to do is update case sizing for that motor. Other electronics can remain the same...

Step 1: Introduction

Features

display showing current position and feedbac
3 customizable height positions with auto hom
calibration of MIN and MAX table position to avoid destroying mechanism and limiting travel range of table

Calibration/Usage

While display is flashing with dashes, set table to lowest position
Press "tilde" button for 3s or until message '-rst' shows to confirm lowest position and afterwards set table to highest position
Press "tilde" button for 3s or until message '-rst' shows once more to confirm max position
Afterwards you can use table with min/max soft. limits and custom positions
To set new position just press one of 1, 2, 3 buttons until display shows "set" message
To "goto" preset position just press 1, 2, 3 buttons
To reset min/max bounds and custom positions, press "tilde" once more as previously it was calibrated

Step 2: How-to

NOTE your table needs to be leveled and manual adjustment shouldn't feel jerky, as it may influence on modfunctionality

print all parts from Thingverse or download them directly from github where are the latest versions
RELAY VERSION - all parts were printed in 0.2 mm layer height but 0.3 should be ok for case-non-modular.stl, for modular parts case-modular-aio.stl, case-modular-cover.stl and case-modular-frame.stl 0.2 mm clearance is used so layer height 0.2 mm or lower is recommended
H-BRIDGE VERSION - all parts were printed in 0.2 mm layer height but 0.3 should be ok for case-non-modular.stl, for modular parts case-modular-aio.stl, case-modular-cover.stl and case-modular-frame.stl 0.2 mm clearance is used so layer height 0.2 mm or lower is recommended
all parts except for buttons.stl, encoder-pulley.stl, keypad-connector.stl and table-frame-tie.stl were printed with supports, but it should work without them...
motor-pulley.stl needs to be printed with PLA with 100% infill or you can buy one of Shaft-Coupling 6-7mm and combine it with GT2_Skarsta_shaft.stl so that it can handle more torque. Shaft-Coupling 6-7mm and GT2_Skarsta_shaft.stl can be attached together with Super-glue
panel-cover-bridge.stl has a tweak for printing without support, but you need clear the first layer on the holes
motor-pulley.stl should be printed with thicker walls or with 100% infill, also print few of these as this part will get permanently damaged when accidentally hit min/max height of table
based on your printer accuracy, may be needed pre-drilling of screw holes

get electronic parts:
- Arduino-Nano
- Rotary encoder
- RELAY VERSION - Relay 1ch
- RELAY VERSION - Relay 2ch
- H-BRIDGE VERSION - H-Bridge
- GT2 160mm belt
- Power Switch
- Power connector
- Step-Down module
- Display
- Display buttons
- 12V motor
- PSU 12V3A - minimal
- PSU 12V5A - recommended (or any other kind os power source like ATX-PSU etc. that can deliver at least 12V)
- Fuse-mount
- Fuse 3A/4A
- Screws M4-16mm for control panel and M3-20mm for motor box (may differ due to printer accuracy)

Build & Flash Arduino-Nano via platformio
Cut off 100mm from the end of Skarsta handle or use Hex-Key 6mm which will be used to connect motor to table

Step 3: Wiring - RELAY VERSION

Step 4: Wiring - H-BRIDGE VERSION

Step 5: RELAY VERSION Motor Case

Add Arduino-Nano to case, insert it into notches a slowly push usb connector down. It should be quite tight fit
Wire up power connector, power switch, buck converter and relays
Fix power connector with super/hot glue in case
Add cables to buck converter output and mount it slowly to the case, it should be tight fit
Connect motor to relays and mount it to case, fix it with 6 screws
Cleanup wiring and secure relays to case with few screws
Add Rotary encoder next to motor and fix it with screws or nut
Insert nut & screw into motor pulley and secure it on motor shaft
Add timing belt with encoder pulley onto encoder, readjust encoder position if belt is loosen or too tight
Wire up rest of the electronics as shown in the wiring diagram
Fix dupont cables for display + keypad with super/hot glue into cable connector part and afterwards fix it with super/hot glue to case if needed
Add hexagonal rod and slowly insert it into table, if needed adjust hole for rod hole with original lever
Fix mounted motor case with 7 screws to table

Step 6: H-BRIDGE VERSION Motor Case

Add Arduino-Nano, buck converter and h-bridge to case cover plate and fix them with screws, if needed use screw-spacer.stl for buck converter
Wire all components on case cover plate together based on wiring diagram (optionally 2 Female 8-pin sockets can be inserted cover plate slot for GND and V5)
Add motor, PSU switch, PSU and keypad connector to case frame
Add Rotary encoder next to motor and fix it with screws or nut
Insert nut & screw into motor pulley and secure it on motor shaft
Add timing belt with encoder pulley onto encoder, readjust encoder position if belt is loosen or too tight
Wire up rest of the electronics as shown in the wiring diagram
Fix dupont cables for display + keypad with super/hot glue into cable connector part and afterwards fix it with super/hot glue to case if needed
Insert 3 screws to case where cover plate overlaps frame and afterwards secure cover plate with screw-hollow.stl these will hold case parts together and prevent screws from falling out while you can still tight them through inner hole
Add hexagonal rod and slowly insert it into table, if needed adjust hole for rod hole with original lever
Fix mounted motor case with 7 screws to table

Step 7: Display + Keypad Case

Paint button caps with paint or nail polish
Insert button caps to tactile switches
Insert them to panel top case part and fix them with super/hot glue or with their pins
Insert 7-segment display to panel top part
Pass wires through panel bottom case part and secure them few centimeters below the end with zip tie
Wire up all the buttons and display with cables
Fix top and bottom case parts with 6 screws
Connect cables to motor case and mount it with 3 screws to table
Cleanup the cable management with few table-frame-ties

Step 8: Error Codes && Handling

if any Error message bellow is showed on display it is needed to manually power down/up table to be able to operate once again, after any of error pops out it is advised to closely inspect table if the problem reoccurs if so open an issue

Error code and description