What did you buy today? Post your latest purchase!

[mnementh]

Having done a LOT of fan and ductwork type stuff, NEITHER of those solutions are actually "fit for purpose". The ducted filter cube decreases the airflow velocity to the point of uselessness for fume extraction, and the ducted Hakko thing... SERIOUSLY?  All it does is approximately double the space taken up by the thing when stowed, and EVEN WORSE space-wastage when deployed. 

Just like mine with the square of filter cloth tacked to the front of a fan, bean's take has the beauty of form following function. KISS applies here in the absolute; unless the mod improves effectiveness (which the increased filter surface on bean's design DOES while also directing airflow much more usefully), it's pointless.

mnem
 

[mnementh]

@bean - Nice knock-together. I used plastic pop fasteners to hold the filter in place on mine.  If you're going to make a frame, you should 3DP it with hinge flanges like a GoPro mount so you can attach it easily to an articulating arm. One of those things that's been on my DSIGD list for like a year... 

mnem
 

Decided on 12V flop it on the bench option. Laser cut ply or acrylic with three frames, two at the front to sandwich the filter (fairly stiff) between them. Offset from the fan a little so all of the surface will pull air and not be hindered by the motor as much. 150mm on the base front to back for a little more stability. Simple PWM ESC and a jack mounted back there too. Gave me an excuse to model a rough 120mm Fan to add to the collection too.

Still a WIP 

I like it a lot. I'm not sure if this was your intent or not, but f you make it so the filter element applies across the curved surface, you'll decrease air resistance thanks to larger surface area while at the same time directing airflow in a manner that greatly enhances the directionality of fume extraction. Added bonus will be longer life of individual bits of filter. Well-done. 

mnem
 

[Nominal Animal]

For a silent/low noise fume filter, try using two fans in a push-pull configuration on either side of the filter.

Counterintuitively, you might want to use a reverse cone in front of the intake to increase the speed of the airflow, i.e. a cone where the air intake is at the narrow end.  This way the speed of the airflow is much lower at the filter, and even low-noise fans can generate enough of a pressure differential or airflow through the filter.

It might be interesting to do a three/six-fan setup, where the fans are side by side, and the air intake is a horizontal slit only a few mm tall; i.e. a triangular prism with one of the three faces facing the fan, and the opposite edge is the air intake.

[mnementh]

Fan in front of the filter is not a good idea with soldering smoke; it carries a large component of vaporised rosin which will quickly coat an unprotected fan with nasty stuff that looks like tobacco tar and contains lead/tin/antimony.  The little bit that gets through the charcoal filter material we're using still makes things noticeably nasty-looking after a few dozen hours usage.

Two fans in a Vee works very well and enhances stability; it also allows you to use slower, quieter fans and still get the air velocity at the filter you need for useful fume suckage. Downside is heavier, takes up more bench space in use.

mnem
 

[Mr. Scram]

Not a good idea with soldering smoke; it carries a large component of vaporised rosin which will coat an unprotected fan with nasty stuff that looks like tobacco tar.  The little bit that gets through the charcoal filter material we're using still makes things noticeably nasty-looking after a few dozen hours usage.

mnem
 

We don’t need the fan to look good.

[mnementh]

QUICKLY. And yes, enough to quickly affect how it performs as a fan.  Also lead/tin/antimony component of the residue completely defeats the intent of using a charcoal filter element.

mnem
Ask how I know. 

[beanflying]

The issue with increasing the airflow speed or adding more fans is noise so it is a balance, this nominal 3-4W fan wound back is to control the noise. Make it sound like a jet taking off and it will sit on the shelf unused, make it to bulky or clunky and you won't find room on the bench for it as an everyday item and it will also sit on a shelf unused. The small extension on top of the fan isn't just aesthetic it will help draw the air up off the bench and reduce air from above.

Should have started a separate thread too 

[mnementh]

There, there bean; it's not that bad. We all know you didn't MEAN TO nerd-snipe us. 

110% true on all counts; I learned this the hard way from my own travels down this very road.  I built several; the two best were a single 5" AC powered muffin fan and two 120mm slimline 12V ones in a Vee with a single piece of filter across the front of both of them. That one was a bit quieter so got used more, until it got knocked off the bench and one of the fans suffered 2 broken blades. The AC fan has been it for several years, and those are the very reasons why. My recommendations are:

1) Design as simple as possible so you actually bother to build the fu**ing thing. The quick & dirty fume extractor you have on hand ALWAYS beats the one you're "gonna make" for the next three years.  Know thyself, plan thine design accordingly. 

2) Make it small & convenient so you don't mind keeping it at the back of your bench, and so you bother to pull it up to your work. 

3) Choose a  fan that's as powerful as you can tolerate the noise, or plan on the hassle of slowing it down. When in doubt, see number one above. 4-6" (100-150mm-ish) seems to be the sweet spot for both.

4) AC-powered typically have a higher power/lower noise ratio. Some of them are little hurricanes though.  AC-powered is by default less hassle from a use & standby/storage perspective. (As long as you can have nice little plugs like we do in the US)

mnem
 

[Mr. Scram]

QUICKLY. And yes, enough to quickly affect how it performs as a fan.  Also lead/tin/antimony component of the residue completely defeats the intent of using a charcoal filter element.

mnem
Ask how I know. 

Anything that comes off the fan is sucked into the filter. It’s not a helicopter blade, it’s just a fan. Even crudely shaped sheet metal jobbies still throw air in roughly the right direction.

[mnementh]

QUICKLY. And yes, enough to quickly affect how it performs as a fan.  Also lead/tin/antimony component of the residue completely defeats the intent of using a charcoal filter element.

mnem
Ask how I know. 

Anything that comes off the fan is sucked into the filter. It’s not a helicopter blade, it’s just a fan. Even crudely shaped sheet metal jobbies still throw air in roughly the right direction.

You can't handle the fan and NOT touch the accumulation, causing it to flake off onto yourself. Therefore comes the risk of ingestion. The filter by its nature traps the accumulation within itself, greatly reducing the amount of accidental exposure. AS IS ITS SOLE REASON FOR BEING.

Clearly you've never actually handled such a thing or this would be obvious to you. Do it, use it yourself for a few dozen hours and come back here and tell me you think it's a good idea. 

Cheers,

mnem
 

[Mr. Scram]

You can't handle the fan and NOT touch the accumulation, causing it to flake off onto yourself. Therefore comes the risk of ingestion. The filter by its nature traps the accumulation, greatly reducing the amount of accidental exposure. AS IS ITS SOLE REASON FOR BEING.

Clearly you've never actually handled such a thing or this would be obvious to you. Do it, use it yourself for a few dozen hours and come back here and tell me you think it's a good idea. 

Cheers,

mnem
 

Most of us heave learnt not to stick their fingers in fans although admittedly it takes some a bit longer than others.

[mnementh]

No, some of us are smart enough to know which side of the fan will bite you and therefore needs a grille. Which ALSO gets coated in lead-bearing rosin if you try to put the filter on ass-backwards. 

mnem
"Never argue with a fool. First they drag you down to their level, and then they beat you up with experience."

[Mr. Scram]

No, some of us are smart enough to know which side of the fan will bite you and therefore needs a grille. Which ALSO gets coated in lead-bearing rosin if you try to put the filter on ass-backwards. 

mnem
"Never argue with a fool. First they drag you down to their level, and then they beat you up with experience."

Spoken like a true master.

[beanflying]

This rear grill may not be totally finger proof but should keep most numpties from inserting other delicate things in it. 

Tabs, mounts, holes etc added and olff to the Laser tomorrow with it but the Bakers Dozen parts came back with no interferences on Fusion so it is off to a good start.

Re fan power/noise DC is simple for speed control and 99% of use have one if not more variable power supplies on the bench so I see no reason to use mains fans not to mention cheaper.

Two knurled thumbscrews to do a filter change as I have them on hand already.

[Zucca]

I like the two position option



if you solder low on the table you want high suction power and flat suction area instead of vertical.

[mnementh]

This rear grill may not be totally finger proof but should keep most numpties from inserting other delicate things in it. 

Tabs, mounts, holes etc added and olff to the Laser tomorrow with it but the Bakers Dozen parts came back with no interferences on Fusion so it is off to a good start.

Re fan power/noise DC is simple for speed control and 99% of use have one if not more variable power supplies on the bench so I see no reason to use mains fans not to mention cheaper.

Two knurled thumbscrews to do a filter change as I have them on hand already.

I like it. I'd like it more if you designed so the filter followed the curved plane; but then this would probably have to become a 3DP project, not a laser-cutting project. 

Rear fan grill isn't that critical; it's not even necessary. Even if you're daft enough to stick something tender in there, it can't hurt you; it'll just startle you as your numpties are only bouncing off the trailing edge of the fan blade. 

I have several AC fans in my collection; including one NIDEC 6-incher from the 6-Million-Dollar-Man era that sounds like a jet engine churning when it's on. I keep it for terrorizing curious kitty cats away from my work. 

For those playing along at home: Use caution when running DC fans on reduced voltage. Most computer-type axial fans use brushless motors; running too low voltage can cause premature failure as reduced airflow combines with FETs or IC driver final stages operating in or near linear mode overheat quickly due to high loading as they try to compensate.

My usual rule of thumb is to test with a variable PSU; find the minimum startup voltage and then never run less than ~150% of that voltage. Much better solution is to choose a fan with built-in thermistor and substitute a pot; they control their own speed via PWM. 

Carry on!!!

mnem
 

[Black Phoenix]

Well in the beginning of this month I came around this deal:



This dude was selling the item for 150$ as starting bit, with best offer available. Well I tried to offer 200$ and he accepted. Of course after that I started to feel a little cold feet, same as the common "If something seems too good to be true, it probably is too good to be true." Add 60$ for shipping and we have the final price.

So wait time for the shipping and everything and what do you know... IT WAS.

So together with that I had come to pick up in Hong Kong the rest of this month haul:



So the Fluke 87V plus the iFixit Pro Kit, and a new smaller 65% Mechanical Keyboard.



Kinda like this format of keyboard, specially now that I have space constraints. I'm even thinking into changing the mouse to a trackball.




Regarding the DMM, all the fuses are OK, every function that I tried worked OK, the equipment is really in pristine new condition. Not a bad deal I must say.

Another one to add to the 289 and the 54-II back at home.

[Nominal Animal]

Two Teensy 4.0 dev boards with NXP iMXRT1062 chip, programmed using Teensyduino in the Arduino environment: 600 MHz Cortex-M7 with 1M RAM, 2M flash (less 64K for recovery and EEPROM emulation), with 40 digital I/Os, two high-speed USB (480 Mbit/s), size 1.4" × 0.7" (35.6mm × 17.8mm).  22€ apiece from a local Finnish PJRC distributor, Mandu.  These are beasts, although the small footprint means only a subset of the chip features is exported to pins.

[technix]

Some Gowin FPGAs. Particularly, GW2AR with 8MB 3.3V DRAM and 8MB 1.8V PSRAM, in QFN88 package.
I ordered way more than I can use, which means, if all goes correctly, I will sell some leftover dev kits (like the Trenz GN1N-9 form factor with built-in JTAG) here.

I am marking one for myself. What exact chips are you using though?

[beanflying]

What I didn't buy today and just because I have polluted (and caused others to pollute) this thread for the last couple of days

Not glued and no fasteners installed but first time off the Laser all the bits snapped into place and work as planned. 

Nicely stable and the rear leg could be shortened or maybe removed as the fan makes it sit on the bench well. Only made from junk ply but I have some nice hardwood veneers to maybe do a nicer MK2.

[mnementh]

@bean - Nicely done. Yer gonna make me have to look into laser-cutting again, ya evil bastahd. 

mnem
 

[Bud]

What I didn't buy today and just because I have polluted (and caused others to pollute) this thread for the last couple of days

Not glued and no fasteners installed but first time off the Laser all the bits snapped into place and work as planned. 

Nicely stable and the rear leg could be shortened or maybe removed as the fan makes it sit on the bench well. Only made from junk ply but I have some nice hardwood veneers to maybe do a nicer MK2.

Nice. I think people will buy it like crazy if you make a kit.

[bitseeker]

@bean - Nicely done. Yer gonna make me have to look into laser-cutting again, ya evil bastahd. 

mnem
 

I second that commotion.

[cat87]

   Got a Metcal SP200 for cheap.  Wanted one for years. Real nice bit of kit and the tips it came with are still up to the task. Though will also invest in some chisel tips.

[Mortymore]

Something to increase the meters collection... a power clamp meter IPM244F.

I had to go stick it "inrush" to do a first test.
Now, I got the power.