Hi everyone, Tom here, i today i got the final version of Watterott electronic’s Silent
Step Stick with me.
I already took a look at the “preview” version, which i already liked quite a bit,
but this is the one that you can now actually buy.
It’s still based on the same Trinamic TMC2100 chip and, electrically, is pretty much the
same thing, but it got a few features that the preview one was still missing.
If you haven’t seen the video about that version yet, click the annotation on-screen
now or the link in this video’s description to receive a free viewing of the technical
review!
So the first obvious difference: Gold, baby!
Instead of just a plain tin plating, the board’s solder spots and the pin headers now are gold
plated, making them a bit easier to solder to and giving a more reliable contact down
to the base board.
Also, the boards are now brown-black instead of the default green.
Which doesn’t really make much of a difference, but it’s details like these that i just
love.
Speaking of details, i’ve already talked about the configuration pins and how the jumper
setup on many popular boards, especially on the RAMPS, makes it impossible to put the
driver into certain drive modes.
The new driver board design includes a couple solder jumpers that give you more flexibility
for configuring the exact drive mode, but for certain configurations, including the
one i’d recommend, which is spreadCycle with 16 to 256 times microstepping interpolation,
you will still need to solder in additional jumper wires.
However, two of the configuration pins that aren’t broken out to the pin headers can
now also be configured with two solder jumpers, and those two extra options, which control
the blank time and hysteresis of the chopper driver, give you another way of tuning the
driver for example in case your particular motors whine a lot with these drivers, like
mine did.
And as promised with the preview version, the two diagnostics outputs and the reference
voltage input that allows you to set the motor current through software on supported boards,
are now also broken out and can be hooked up with extra pin headers.
Even though the reference voltage pin is in somewhat of awkward off-grid spot, which means
that it’s basically impossible to solder in the diagnostics pins / and the reference
voltage one.
Now, the biggest change and the one i like the most isn’t all the obvious at first
glance, but also something that you should definitely keep in mind when assembling these.
When you look at the new SilentStepStick vs the old one or any other driver, you will
notice that the pinout doesn’t match up!
And that’s because these are intended to be used upside-down.
/ And that absolutely makes sense, for one specific reason: The Trinamic driver chips,
just like all the other driver chips, / is made to be cooled from the bottom.
So if you simply stick a heatsink to the # top of the casing of the IC, all the heat will
have to travel through the plastic potting around the actual chip, which is a terrible
conductor for heat.
So the proper way of cooling one of these drivers, and the way Watterott chose to do
it, is to use thermal vias through the PCB under the chip, which are soldered to the
metal pad on the bottom of the driver IC.
That way, the heat is conducted away through the solder and the copper plating in these
vias, which means that if you stick the same heatsink to the bottom here, the actual driver
# chip will stay much cooler than if you glue it to the top.
Which allows you to use higher currents before the chips overheats.
One potential issue with the upside-down configuration is that a regular potentiometer for setting
the driver current will be inaccessible once you plug the driver in.
Watterott solved that very elegantly by using a special potentiometer and a hole through
the PCB, which allows you to adjust the potentiometer from the side that will be facing up once
it’s mounted.
And i really need to applaud Watterott for making the first driver boards that i’ve
seen that implement thermals for the driver IC correctly.
One more thing that wasn’t clear for the preview version yet was pricing, and the way
it works out is this: These are brand-name, well-designed powerful or # silent drivers,
if you prefer that, and compared to getting the regular Allegro A4988 drivers / or the
beefier, but maybe not as elegant Texas Instruments DRV8825 drivers, they are in the exact spot
they should be.
Currently, including tax, they are 9 Euros 95 per piece, compared to around 6 Euros for
an Allegro board or about 13 for the TI one.
Of course, none of those prices can compete with the horrible, but horribly inexpensive
Geeeeeeeetech or generic Chinese drives, but those are in somewhat of a different league.
Sure, i expect the prices to drop over time, but even right now, they are very reasonably
priced and offer a more sophisticated alternative to the Allegro drivers, and i my opinion,
kinda make the TI chips obsolete, at least for 3D printers.
So there you have it!
They are very nice drivers and i’m really looking forward to seeing 3D printers or even
new integrated 3D printer electronics pop up that use these new chips or driver modules.
A link to Watterott’s drivers is in the video’s description, check them out!
And i’ll see you in the next one.