Voron 2.4 Build — Roll-in Spring T Nuts

November 21st, 2021 by Keith Neufeld

To attach things to T-slot / V-slot aluminum extrusion, one typically puts some kind of nut into the slot of the extrusion; and it’s called a T nut because its cross-section typically has a (potentially abstracted) inverted T shape.

Roll-in spring T nuts

The blank end of this kind of T nut, apparently called roll-in spring T nuts, has a recessed spring and a bearing swaged into place, just protruding from the lower face. The spring pressure on the bearings keeps the nuts from sliding around in the slot on their own, which is really handy during assembly and disassembly.

I was aware of this type but hadn’t used them before and was delighted to find that they can be installed (and with considerably more effort, deinstalled) through the face of the slot. They’re slim enough that they “roll” into the face of the slot, landing slanted on an edge; and then with a downward push, they orient into their final position and the spring pushes them back up to hold their orientation against the slot and retain their position.

Voron 2.4 Build — Frame Assembly

November 21st, 2021 by Keith Neufeld

I got interested in having a Voron 2.4 3D printer after seeing after seeing Tom Sanladerer’s video review of his completed build. But at the time, the full build cost about $1500 — a little high for my taste — and only a partial kit was available and you had to source some of the parts yourself — not interested — because the Voron is an open-source design, not a product. But not too much later I found a full kit from Fysetc on AliExpress for just under $1000; and after an extensive wait and repeated untruths about the status of the shipment, I have my kit and I’m started to assemble it.

Plenty of others have documented the entire build process; I’ll only share particular items I find noteworthy and different from other printers I’ve assembled.

2020 aluminum extrusion joined by M5 machine screws

The first is the frame joinery. I’m sure the Voron is not the first thing in the world to use the heads of M5 machine screws in the T-track, but I’d not seen it done before. You need an access hole through the aluminum for the hex key to drive the screws; but unlike joints that bolt through the aluminum, the access hole doesn’t have to be precise for you to be able to align the joint.

Voron 2.4 frame

It ends up fairly square and fairly rigid, with the squareness aided by assembling on a discarded scrap of granite countertop.

And yes, that frame is almost as wide as my roll-away dishwasher. I got the kit with 350-mm-cube build volume, which is larger than I need; and I’d probably have picked the 300-mm-cube build volume had there been a full kit for it when I ordered. One of the Voron’s claims to fame is fast printing; and the mass of the larger gantry for the 350-mm printer can be expected to impact the top acceleration I can use without ringing.

Fussing with My Server Power Supply

November 13th, 2021 by Keith Neufeld

This wretched miserable piece of notworkingness has been causing me a fair bit of grief in the last couple of weeks.

Dell Poweredge 750 server power supply

This is the power supply from the Dell Poweredge 750 (yes, that’s 750, not R750) server from which, if it is still near the year 2021, you are being served this web page. A couple of weeks ago, it developed the new behavior of powering up perfectly well to start booting the server and start running the BIOS tests and then shutting off again.

Being in a bit of a hurry at the time, I grabbed my spare ATX power supply and hooked it up to get the server running again with the lid open and deal with the original power supply later. But with the new power supply connected, the server wouldn’t boot at all, because

Dell Poweredge 750 server power supply motherboard connectors

what is this??? Oh, for a larff, let’s move the purple 5V standby wire from the ATX mother board connector to the PCI power connector, har har! So with the spare power supply connected, the server wasn’t receiving 5V standby [where it wanted it] to run the On button to turn on the power supply and the server.

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What Shape Portable USB Powerbank?

November 4th, 2021 by Keith Neufeld

Cort and I would like to embed lithium cells in portable projects and want power management that:

  1. steps up the lithium cell’s 3.7 V to a well-regulated 5 V
  2. safely charges the lithium cell from some source
  3. powers the load while charging the cell

I knew it’d be easy finding power management modules that met the first two points, but I wasn’t sure whether the third point (power the load while charging) would be a ubiquitous feature, or even clearly called out in documentation. Fortunately, while browsing power management modules, I quickly found that the HT4928S mobile power management chip supports all three, and found cheap modules both with and without USB connectors on them, and ordered a batch of each style.

18650 lithium cell with power management modules

Now I have them and need to test that they work as described, preferably without burning down my house or pocket. The obvious test is to hook one to a secondhand 18650 cell I have lying around. While I’m at it, I may as well 3D-print an enclosure for it and have a spare USB powerbank.

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0.6-mm Nozzle for Faster Printing

September 7th, 2021 by Keith Neufeld

I recently brought home a trio of Ender 3 Pro printers needing a little love … that’s a story for another day. But this weekend I put a 0.6-mm nozzle on one of them for doing faster draft prints. Let’s see about some PrusaSlicer settings to take advantage of that.

Draft of a wall holder for a chef’s knife:

  • 9h12m for Prusa MK3S, 0.20-mm layers
  • 11h13m for Ender 3 Pro, 0.20-mm layers
  • 4h22m for Ender 3 Pro with the 0.6-mm nozzle

4h22m print on Ender 3 Pro with 0.6-mm nozzle

Okey dokey, what do we need to do to configure to use a 0.6-mm nozzle?

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The Lawn Under the Lawn

August 22nd, 2021 by Keith Neufeld

“Yak shaving,” well-known among a certain class of nerds, refers to artificial dependencies that you insert before your ultimate objective, distracting you and derailing you from getting the job done. My favorite sample yak shaving is on Seth Goden’s blog from 2005.

Yak shaving would be: I want to use the lab power supply on my workbench, but my CupCake is hooked up to it, and I haven’t finished getting the CupCake’s aging extruder motor to work, so suddenly I’m spending the weekend working on the CupCake, so I can get it fixed and move it out of the way, so I can use the power supply under it to do … whatever it is that I was going to do. (This is a fictional, but relatable, example.)

Some time back, Cort said to me:

Doing technology work is often like going out to mow your lawn, and you think it’s going okay, but partway into it you discover there’s a whole ‘nother lawn under your lawn, and now you have to mow the one underneath before you can mow the one you thought you were there for. And then sometimes you start mowing the lawn under your lawn and you find out there’s another one under that, too.

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Tryna Print Some TPU

August 6th, 2021 by Keith Neufeld

I picked up a couple rolls of Overture TPU and it’s lovely stuff — supple and squishy and I really want to use it — but I just can’t get it to print right.

Block printed in Overture TPU with insufficient extruder tension

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Getting Started with D-duino-Clone ESP8266 and SSD1306 0.96″ OLED Module

August 6th, 2021 by Keith Neufeld

D-duino clone ESP8266 and SSD1306 OLED module

I’ve been interested in the ESP8266 for a long time; and way back in 2017 when I first learned that support had been added to program them with the Arduino IDE, I ordered this totes adorbs little guy, who’s been patiently waiting for me until today. In the process of figuring out how to program it, I learned that it’s a clone of the D-duino.

I find the ESP8266 market space very confusing, with lots of boards and lots of assumptions that you already know what you’re doing. It took me a fair bit of searching and fiddling to get this working. In case you’re in the same boat I was until yesterday and want to try this yourself, here is one currently-available product [no affiliation] that I expect will be identical to mine. You may find others; and/or you may not even need this walkthrough, both of which are perfectly fine.

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CNC Fabric Cutterhead Prototyping: BLDC Motor

April 24th, 2021 by Keith Neufeld

Last fall when I was looking for ways to drive a reciprocating fabric cutter, Ed Nisley suggested that I look at hobby brushless DC motors as possible sources of enough of both speed and torque. Not knowing anything about their care and feeding (and after a significant delay), I did my homework and learned how to lash one together well enough to make it spin.

After which I inevitably put together a completely unusable cutterhead prototype.

reciprocating cutter prototype with BLDC motor and skate bearing

My intent all along was to use the same tattoo gun brass cam as on the tiny motors, but last weekend I couldn’t find a tiny hex key for the set screw to remove it from the previous prototype and affix it to the BLDC motor. It being a very short drive from Missingtherighttoolville to neighboring Badideatown, I printed a plastic cam and new connecting rod to fit a standard skate bearing. Let me tell you, turning on that cutter was like holding a powerful vibrating thing with a razor-sharp blade in your hand.

It didn’t cut the fabric particularly well, either. It had plenty of torque but lacked either sufficient speed or travel to cut unclamped fabric; it just shoved it out of the way. (It cut just fine when the fabric was held in tension, but that’s not the objective.) The eccentric mass of that heavy skate bearing did not motivate me to turn it up faster, particularly when I already had the other cam in mind.

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CNC Fabric Cutterhead Prototyping: More Speed (Less Torque)

April 18th, 2021 by Keith Neufeld

In a previous installment, I used a 900-rpm gearmotor in my reciprocating-blade prototype and it didn’t have the speed needed to cut fabric sitting on a styrofoam spoilboard. The only place I could find to order a higher-speed version was AliExpress, and it took a while to arrive.

reciprocating cutter prototype

Quickly swapped into the same prototype cutterhead, with predictable results: It has a higher no-load speed but bogs down in the cut. This style of gearmotor won’t be my solution.