Chapter 8 – Electronics
For cost reasons it was clear from the outset that an 8-bit system would be used. 32-bit systems are now falling in price, but would still exceed the budget.
However, the clock rate or computing power of an 8-bit system is also sufficient to operate the simple Cartesian kinematics of the Tantillus.
A 19V or 24V power supply is used for high stepper dynamics and good heating performance of hot end and heating plate.
A laptop power supply is used. There is no need for additional wiring of a socket or connection cable, the touch protection is excellent and the price is also very attractive.
With these frame parameters the selection of available stepper drivers is strongly limited.
As things stand today, there are actually only drivers with a Trinamic chip to choose from. Technically older drivers like A4988 or DRV8825 are much cheaper, but the unbearable noise should be worth the meanwhile low surcharge for Trinamic drivers.
Currently 3 different types of Trinamic drivers are recommended
The TMC 2100 is the classic TMC driver. It is quiet, powerful and can be tortured to an astonishing degree.
Due to the good experience, the classic version, the TMC 2100 in the 3.3-5V version, should be chosen.
These generate considerably more waste heat in 24V operation than the TMC 2100 driver in the pure 5V version, but are more future-proof.
Should an update to a 32Bit system be pending, the drivers can still be used. Sufficient cooling capacity is available.
The TMC 2100 are operated in SpreadCycle mode and interpolation from 1/16 step to 1/256 step. To get the drivers safely into the desired mode they have to be soldered together as follows:
TMC 2100 – Solder a bridge from GND to CFG1. Remove pins from CFG1, CFG2, and CFG3.
The more modern TMC 2130 can be used as an alternative to the TMC 2100, but are slightly more expensive. They offer more features like StallGuard. Meanwhile the features are supported by all relevant firmware. In order to use e.g. Stallguard additional wiring work is necessary.
Strictly speaking, you don’t need these additional features either, they are more of a gimmick.
However, if you use the TMC2130 and its features, you can do without the endstops for X and Y.
The TMC 2130 should also be operated in SpreadCycle mode and an interpolation from 1/16 step to 1/256 step.
The latest and cheapest drivers of the series, the TMC2208, are currently our recommendation. Its biggest feature is the extremely quiet Stealthchop2 mode. This is much more powerful than the StealthChop of the TMC21xx series due to its automatic tuning.
To use the extremely quiet stealthchop mode, no additional wiring or soldering is required. The TMC2208 runs in StealtChop2 mode ex works. All you have to do is solder the pins according to the picture. All jumpers below the driver must be plugged in to use it with 1/16 with 1/256 interpolation.
The TMC2208 is currently the quietest, cheapest and easiest to install driver available.
TMC 2208 – remove pins PDN/UART
All further information about the TMC drivers can be found in Watterott’s GitHub Repo.
Please use only the original StepSticks from Watterott! The Chinese copies are only a few € cheaper in the set. However, the savings potential is not comparable to the potential problems with the copies.
TMC StepSticks do not tolerate reverse polarity/twisted mounting. Therefore, the drivers must be plugged in as shown. The jumpers under drivers can be set at TMC2100, and have to be set when using TMC2208.
MKS Gen with TMC2100 in 1/16 interpolate to 1/256 mode
Due to the small size of the Tantillus and the 19/24V power supply, the 8-bit classic RAMPS is not used. The modular design has some advantages, especially in the case of repairs, but the overall construction has become quite rusty in the meantime.
The search for a suitable board was successful with the MKS gen v1.4. It meets all requirements, low height, 24V suitable, exchangeable drivers,…
Furthermore, the connectivity is better than the RAMPS, the JST-XHP connectors are protected against polarity reversal, besides the low total price, also a nice feature.
Where there is light, there is shadow. MKS has been strongly criticised. To promote their products Makerbase uses all advertising arguments like the alleged GPL license, alleged compatibility with RAMPS,….
However, the board layout and a schematic have not yet been officially published.
So the knowledge of the RepRap scene was used, but nothing was given back to it.
A circuit diagram, etc. can be found here in the Github.
The connection of all components is simple, just follow the connection diagram below.
Please note: The Chinese didn’t take it too seriously when it came to labelling. If the board is supplied with 19/24V, „12V out“ is also 19/24V!
The classic RRD SmartController with 2004 LCD is used as display. Due to the price, size and position of the SD card slot, the display is ideal for the Tantillus.
In one of our test setups an LCD did not work due to a twisted cable, apparently there are different connection cables available. Make sure that the ribbon cables, red cores are connected exactly as shown in the picture.
Electronics – cooling
An 80x80x25 mm fan is used to cool the board and the drivers. The large size makes it possible to use inexpensive, relatively slow and low-noise fans.
Furthermore, the fan covers all areas to be cooled sensibly. However, in order to be able to work properly on the board, we have devised a special feature.
The fan is attached to the housing with 2 magnets. This keeps it safe in operation, but can still be removed quickly and without tools.
- press magnets into holes provided for this purpose
- with the counterpart pay attention to the corresponding polarity of the magnets
- screw the holder to the housing and to the fan
- crimp 2-pin JST plug to the supply line of the plug
If a 12V fan is used, the +pole of the fan must be connected to the StepDown controller. The -pol must be connected to XXX.
If a 24V fan is used, it can be connected directly to the pin header JI7 next to the reset button
- Chapter 0 – Introduction
- Chapter 1 – Housing
- Chapter 2 – Z axis
- Chapter 3 – XY axis system
- Chapter 4 – Heated Bed
- Chapter 5 – Cooling
- Chapter 6 – Extruder
- Chapter 7 – Hotend
- Chapter 8 – Electronics
- Chapter 9 – Spool Roller
- Chapter 10 – Silicone parts
- Chapter 11 – Option: Belt drive cover
- Chapter 12 – Option: Rasterry Pi Zero
- Chapter 13 – Option: UPS for the pi
- Chapter 14 – BOM / Downloads
- Chapter 15 – FAQ
- Chapter 16 – Samples
- Chapter 17 – Concluding remarks