Black Widow pre-build advice for a new guy

General topics regarding the Black Widow
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Mozella
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Joined: Mon Feb 12, 2018 3:06 pm

Black Widow pre-build advice for a new guy

Post by Mozella » Tue Feb 13, 2018 9:26 am

I have a Tevo Black Widow on order but because of the Chinese New Year, shipping will be delayed for nearly two weeks plus normal shipping time. That gives me some time to study build videos, gather various accessories and parts, and prepare for building the unit. This will by my first 3D printer.

As far as I can tell the building process is tedious because there are so many components; however, it doesn’t appear difficult. And because of the great deal of information on the Internet, there doesn’t appear to be any mystery involved. Still, I have a couple of questions I hope someone can answer for me.
I ordered the unit with the BL Touch auto bed leveling option. I believe I will receive the sensor, but without any mounting bracket. I plan to fabricate a temporary bracket from aluminum to start with and then once I’m up and running, print a mounting bracket, perhaps with an integrated PLA cooling fan option.

1. Can I expect the printer to arrive with the firmware appropriate for the BL Touch sensor already installed or not?

One video complained about the noisy control box fan and at least one person recommended installing a new fan and/or installing a pot to slow down the fan speed in order to reduce noise.

2. Is the control box fan too noisy and if so can anyone recommend a better fan option?

I understand the advantages of a rigid structure and I notice that there are various printable brackets and braces files available online. Of course, I won’t be able to print accessory brackets until I fully assemble my printer and get it functioning without them.

3. How big a PITA will it be to retro-fit bracing brackets after the machine is fully assembled? I assume I’ll have to do some disassembly, but I wonder if I can install bracing by just separating some joints without completely reversing the assembly steps. Comments?

One video complained about the X carriage having only three wheels, two on top and one on bottom. He recommended fitting an additional wheel to the carriage.

4. Is it a good idea to modify the X carriage by using two wheels on the bottom? Another video recommended using harder wheels on the Y carriage. Is that a good idea?

Any other tips or hints would be appreciated.

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royg
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Re: Black Widow pre-build advice for a new guy

Post by royg » Tue Feb 13, 2018 11:09 pm

Greetings and welcome to the Forum....

With regard to one of your questions; "One video complained about the noisy control box fan and at least one person recommended installing a new fan and/or installing a pot to slow down the fan speed in order to reduce noise."

Slowing the fan down by wiring a potentiometer or resistor in series with the fan is not a good idea. It certainly will slow the fan down as desired, but the current drawn by the fan motor will cause a voltage drop across the resistor or potentiometer (i.e. Ohm's Law), and that current and voltage drop will result in a significant amount of power (i.e. heat) that will need to be dissipated by the resistor or potentiometer.

A far better solution would be to purchase a suitable good quality fan (probably a computer case fan) of the correct size and voltage, that is designed to run quietly while moving good volumes of air. You might be able to salvage a suitable used fan from an old desktop or server computer case - maybe some dumpster diving .... Our Tevo printers are manufactured to a low price point, which often results in the Manufacturer selecting the lowest cost part that will do the job. Tevo's fans are often the very cheapest available.

The alternative solutions, which are more complex, would be to implement some sort of control over the fan so that it either; a) only runs when required (i.e. when the main board heats up above a threshold value), or b) runs at variable speeds dependant on how high the temperature inside the control box is.

Solution a) from above can be implemented fairly easily by wiring a small thermostat switch in series with the fan. A switch that for example closes at 60 degrees C, would turn the fan on only when needed, and the fan would turn off again when the temperature dropped below 60 degrees C. This video demonstrates the installation of such a temperature switch to control a noisy power supply fan, and should give you a good idea of how to implement this idea (


Solution b) from above is a far more complex solution, and in my view is probably not warranted in this case, because a better quality quieter fan and/or solution a) above would be a far simpler solution. However, if you want to try solution b) above you would need some expertise with programming Arduinos or similar microcontrollers. I'd use an Arduino Nano or other cheap Arduino, coupled with a Temperature sensor to read the temperature inside the case, and then some PID software code to control the speed of the fan based on the temperature. You'd also need a small MosFET and some associated components to actually control the fan, as the Arduino can't supply enough current to run the fan directly. So, as you can see, this solution is more complex, but if you have some Arduino experience, it is a relatively straight forward solution. If you search Youtube with the terms "Arduino PID controlled cooling fan", there are plenty of people describing how to do what you desire. This is one such example - watch a few to find the one that you best understand -


In summary, my recommendation would be to first replace the fan with a quieter better quality fan (probably a good quality computer case fan which are usually fairly quiet). Then if the fan noise still bugs you, then try Solution a) above.

I hope that info is useful.

Regards,

RoyG
Tevo Tarantula - Large Bed - E3dV6 - BLTouch
OctoPi (on a Raspberry Pi 3B)
Cura

Mozella
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Joined: Mon Feb 12, 2018 3:06 pm

Re: Black Widow pre-build advice for a new guy

Post by Mozella » Wed Feb 14, 2018 2:40 pm

Thanks for the detailed reply. I went ahead and ordered a quality fan.

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