obligatory obscure reference


self-deprecating yet still self-promotional witty comment

2017/03/17

E3D Silicone Socks Change PID Settings

Filed under: E3D Printers — jet @ 21:00

Getting ready to put E3D’s “Silicone Socks” on my E3D-V6 and thought, “hey, my kitchen oven mitts are silicone and I can handle 450F pots out of the oven, I wonder how much insulation the socks provide and does it change the PID?”

Two PID tunes later, one without the sock, one with, both starting from a room temp 22C V6 and using the g-code “M303 E0 S240 C8”

Without sock:
p 26.95 i 2.45 d 74.19

With sock:
p 32.75 i 3.54 d 75.8

Which makes sense — p’s change means there is more error (heat loss is lower than bare metal), i’s change is the accumulation of previous errors.  The derivative, d, stays roughly the same because p and i have similar changes in value.  (I did poorly in calculus and am trying to explain this to people who wasted a semester and failed Calc I trying to understand how derivatives work.)

What this implies is that the V6 extruders will heat more quickly thanks to the insulation and will cool more slowly after a print finishes.  I can’t think of any prints where I changed the temperature of the print head during a print so this should “just work” after I update the PID values in Marlin.

2016/04/12

made a thing: rotating “Lazy Susan” tool rack

(Susan wasn’t lazy, she was efficient. There’s a difference.)

After seeing Adam Savage’s take on mobile tool racks I started designing some for my Big Things studio.

Then I realized, no, I need one like ten years ago for my Small Things studio. Cue the cycle of “design, test, improve” and finally I had a version for me. I like it so much I decided to put copies up for sale at Etsy. If you want a custom version for your own special set of You No Touch These Tools we can work something out.

Having a Lasersaur in the Big Things studio is more useful than I expected.

(p.s. Boxing up S/N #1 for Adam tomorrow afternoon.)

2015/09/26

DIY Lasersaur Fume Extraction

Filed under: digifab,Lasersaurs and laser cutters — jet @ 11:36

After building my second Lasersaur, the current release candidate, I started doing a lot more cutting and realized I needed to find a good fume filter. I started designing my own and while doing research discovered that someone had already solved the problem and distributed plans on Instructables. It’s a self-contained laser cutter fume extractor and it does a great job filtering out smoke and acrylic. I sit next to it while running jobs and I can’t smell even a whiff of smoke.

While crawling around under the work bench routing the exhaust from the Lasersaur to the filter I was reminded that my studio (a converted garage) is pretty damn dusty. I’m making dust covers for my computer and CNC headend and putting filters over the cooling fans, and I started thinking about where my Lasersaur gets fresh air. The exhaust fan pulls ~400 CFM of air through a 6″ exhaust port but there’s no 6″ port for air to come in. A few test cuts later and it was pretty obvious I needed dedicated air input to balance the exhaust.

My fix is pretty simple: put an air filter on the opposite side of the cutting bed. The question is what size filter and where should it be located? I tried a few variations with cardboard mock-ups and it looks like having the filter planar level with the cutting bed was the best plan. The filter is some leftover HVAC stuff from the box store and it probably needs a better mount than leftover duct tape, but for now it works just fine.

There are some photos on flickr and here’s a short video of tests and the final result:

2015/09/25

Laser Cutting and Fume Extraction

Filed under: digifab,Lasersaurs and laser cutters — jet @ 12:43

Disclaimer

This is not legal advice or opinion on the rules and regulations for installing or using a laser cutter. These are notes on what I’ve learned and a guide for people interested in having a laser cutter.

What’s all this, then?

I’ve been working with, near, or in toxic fumes since I was a teenager. I’ve wrenched, welded, soldered, used metal working machines, worked on motorcycles and cars, and built CNC equipment, including several 3d printers and a couple of Lasersaurs. I’ve taken and taught safety classes and I’ve still made some stupid mistakes.

It’s easy and inexpensive to get home/shop level digifab equipment like laser cutters but not much out there on what it means to own and operate one.

I wrote this short introduction to laser cutters and fume extraction based on what I’ve learned in work spaces and my studio. I hope that sharing what I’ve learned helps other people interested in setting up a laser cutter.

Fume Extraction

Let’s start by defining what “fume extraction” actually is — removing fumes and particles suspended infumes from an area. Many processes we use create annoying, hazardous, or lethal fumes and fume extraction gets them out of the work area.

Some examples of fume extraction:

  • remove lead and solder fumes from the air around a soldering station
  • remove air containing viral contaminants from a safety area where someone is doing medical research
  • filter or remove greasy smoke out of a kitchen in a home or restaurant
  • remove toxic side-products of welding from a welding station in a closed room

For laser cutters, there are two specific reasons to do fume extraction:

  • remove vaporized particles and fumes from a laser cutter work space to protect the people using the laser cutter
  • clear the air inside the laser cutter to prevent fumes from damaging the media or the laser cutter equipment

Who needs fume extraction?

Anyone generating fumes that are bad for people to breathe, harmful to the environment, or that can damage the tools they are using. That’s a sweeping statement, but there’s a wide scale of materials that can be used as media in a laser cutter. On one end are people who have a business making models but of plywood or cardboard and never cut plastic or etch powder coating off of metal. On the other end is a hacker space, college studio, or Techshop where there’s a “DANGER: do not cut” list and temporarily illiterate laser cutter operators.

Fume extraction isn’t fume filtration!

Note that we’re saying “extraction” not “removal” or “filtration”. Fume extraction means moving the fumes from one area (inside a laser cutter) another area (outside the laser cutter). If you’re laser cutting something that generates toxic fumes and you have wonderful extraction, you’re just moving te toxic fumes to another location. Extracted fumes don’t disappear and an important part of fume extraction is deciding what to do with the fumes. (Saturday Night Live’s “Yardapult” is a funny but real example of what some sites consider fume extraction.)

Laser cutter restrictions

Did your laser cutter come with a manual that explains restrictions on what media you can cut and fume ventilation requirements? Start by reading the manuals and FAQs, there might be limitations on what you can cut or etch because of the materials used to build your laser cutter. One example is what your mirrors are made of — are they backed glass or polished metal? Some mirrors need routine cleaning if you’re cutting smoky materials, even if you have the best fume extraction possible.

What can the fumes damage?

Everything, starting with the person using the equipment and nearby people, then to the equipment (see below), or people near where the fumes are sent as exhaust. If you’re only cutting paper and cardboard and sending the exhaust up a legal fireplace chimney, there’s not much more risk from the fumes than having a fire in the fireplace. If you’re cutting and etching acrylic in volume and dumping the unfiltered exhaust out your garage window, don’t be surprised if the neighbors dial 911 to complain about the smell of burning plastic.

You could also be working with something you think is safe but isn’t. I no longer cut hardboard in my lasersaur because the heat from cutting the wood also does something to the glue and makes the wood sticky. Not sticky in a good, ice cream sort of way, but a sticky burnt glue that sticks to the moving parts and is hard to remove, even with solvent.

Did you read the Material Safety Data Sheet (aka “MSDS”) for the media you’re cutting and does it cover burning the material or fumes? What happens if you laser cut kevlar or styrene? (That’s your cue to go find the MSDS documents for these materials.) Depending on where the laser cutter is installed, there might be requirements from the FDA, EPA, OSHA, local business codes, labor codes, safety codes, etc. (Reminder: I’m in the US and not a lawyer, so I’m mostly going to make vague references to US legal systems and ignore the rest of the world.)

How bad are the fumes, really?

I took apart a laser cutter for parts and took photos of the wear and tear caused by fumes. It was used in a machine shop with good fume extraction and there was still a fair amount of damage to the internal parts. I don’t know what they cut but the amount of rust and corrosion suggests that it was releasing fumes you shouldn’t breathe.

What do you do with these fumes?

So you’re pulling the fumes out of your laser cutter, what do you do with them other than just vent them out a nearby window?

It still depends on the answer to: “What are you cutting?” Did you read the MSDS? Does it even have a MSDS? Note that a MSDS isn’t going to list “cutting by laser” it’s going to use more generic terms like “burning,” “melting,” “smoke,” or “vapors”.

If you’re only cutting something relatively safe, say paper or balsa, you’re creating “wood smoke” which is an easy problem to solve.

Do you know what the media you’re cutting is made of so you can find the MSDS? Before you etch a stack of Moleskin brand sketchbooks, do you know what they’re made of? PVC. Ok, so what happens when you etch and cut PVC? It releases hot chlorine gas that quickly converts to hot hydrochloric acid, and that acid is not good for a laser cutter’s internal parts or the people running the machine.

What if there’s no MSDS? This is where you get to do some science so you can figure out what fumes you’re generating. Cutting thin plywood generates mostly wood smoke, cutting MDF or hardboard means you’re also cutting a lot of glues or maybe paint. If you’re laser etching old paint, is there lead in that paint and the fumes that comes off the etch?

Plan on filtering your fumes

For recreational or hobby use it’s pretty easy to filter fumes and the cost is relatively low to that of a laser cutter. There are a variety of plans online and you can find one that fits your needs I suspect that using a laser cutter a few hours a week generates less air pollution than a gas lawnmower, but neighbors won’t complain about lawn mowers the way they will about the smell of burning plastic.

If you’re working in a manufacturing or art space, filtration could be cheap or free. If there’s already extraction for welding fumes or metalworking machines, you might be
able to use theirs depending on the fumes you generate.

If I were running a professional job shop or a hacker space a commercial filtration system that could handle the nasty fumes from some plastics and resins would be worth the investment. This also goes back to the issue of local regulations, you might have to have some sort of professional certificate or verification that your filtering system works.

Legal restrictions

If you’re renting or don’t legally own and control your space, you’re going to have to go by the owner’s rules. If you’re at a university you’ll probably need to talk to facilities, if you’re in an apartment complex that’s the landlord, or “ask your parents”.

In the US we have federal, state, county, city, local zoning, and various safety restrictions related to wildlife and waste discharge. It could be as simple as “filter your fumes and don’t annoy the neighbors” — I know a few people who have run laser cutters in their garage and never gotten a complaint.

If it’s a hacker space or business getting a laser cuttere there are additional regs to follow. There might be fire code regulations, safety requirements, or additional rules to comply with along with ventilation rules. I’ve seen local regulations where a permit (which costs money) and inspection (more money) are required for an exhaust vent larger than 4 inches in diameter. The regs can be as simple as “exhaust vent” or as specific as “industrial exhaust vent for fabrication equipment”. When I was looking to rent studio
space within Pittsburgh city limits, if I asked about “exhaust ventilation” the landlord just said “no”. No question of what I wanted to vent, they simply didn’t want to deal with exhaust issues.

Question time!

Please leave questions (and answers) in the comments, if there’s enough interest we can turn this in to a FAQ or wiki.

2012/09/03

MendelMax Update

Filed under: digifab,Mendel — jet @ 12:07

The build is almost finished, all I need to do is build the extruder and get host software running on my Mac or Wintel box.

Instead of doing the build (like I planned) I’m spending a lot of time sitting after knee surgery. I do a lot of my hacking/tinkering either standing or sitting on the floor, neither of which has been much of an option for the past few weeks. Deep knee bends (aka “catcher bends”) caused my knee to make a bad noise, the doctor agreed it was bad and to stop making that noise until surgery. Surgery probably fixed it, but now I have ~3 weeks of sitting and taking it easy on my knee.

I’m posting photos to flickr as I make progress.

2012/05/07

Engineering Lesson 101

Filed under: Arduino,Hacking,MakerBot,Rants — jet @ 09:46

I think it’s been 10, maybe 15 years since I’ve actually worked on open source software as an author. I’ve helped fix bugs in things like Arduino and ReplicatorG, but I haven’t done anything major on my own.

Until Friday, when my frustration with a certain class of software got the perspective and skill of my being a professional engineer. Instead of complaining, instead of getting frustrated with how someone else managers their project, instead of not being able to pull rank and make them do it my way, I can just go write my own and hand it out.

It’s a nice feeling. I don’t think I’d have gotten here without writing it-cannot-fail code for security and privacy projects as a day job. That sort of rigor is like daily exercise for the brain, like daily exercise or workouts only for the brain.

2012/03/17

An improved tensioner for the MakerBot Mk7 head

Filed under: MakerBot — jet @ 18:54

Soon after I started testing the Mk7 head it stopped moving plastic, period. I had a working Mk6 handy and a Mini MakerFaire to attend, so I fell back to the Mk6 and decided to let other people debug the Mk7.

However, nobody on the MakerBot list really had a reason or a fix I liked, so I took it apart to fix on my own.

The first thing I discovered was that the pressure mechanism for pushing the plastic against the stepstruder was not pushing hard enough, due in part to scratches on the head’s surface.

The second — and more important — thing was that the stepstruder gear was filled with shreds of plastic. It came off easily, so like the Mk6, just pushing the plastic harder would clear the junk out of the motor.

But how to do that?

Like this.

It’s really that simple. Grab a spare M4 bolt from your parts kit, buy a wingnut at the local hardware store and glue/Loctite the wingnut to the end of the bolt.

I set it up, dialed in a temp of 240C (see earlier posts about temperature), and it forced plastic through with no problem at all. Even a 5 minute run ran without any problems at all.

Now to print some test models….

MakerBot Stepstruder Mk7 Temperatures

Filed under: MakerBot — jet @ 18:47

I had the Mk.7 on the “needs help” bench while doing the previous set of temp tests. I took it apart and discovered the problem with it not pushing plastic was the tensioner against the drive. It had scratches and the drive pulley was clogged with plastic. After fixing that — see the next post for my cheap and adjustable tensioner — I put it on the Cupcake and did another set of temperature tests.

Like the previous set of tests, for temperature reads I used:

  • built-in sensor that ReplicatorG software reads
  • Fluke 88V temp sensor with temperature probe. Not a cheap device but the readout is 0.1C and it’s fast
  • $20 BBQ grill cooking thermometer. Cheap, easy to use, but I think their goal is to make sure I don’t kill someone with undercooked poultry.

As with the Mk.6, the temperatures are lower on Replicator than on the other two sensors, so I need to run with much hotter temps than are required by the instructions. At this point I’m considering adding an offset/calibration value in the software so that the read temp is adjusted properly.

(The images are hosted on flickr for easier commentary)

Mk.7 with software 0033

2012/03/03

MakerBot Stepstruder Mk6 and HBP temperatures

Filed under: MakerBot — jet @ 16:19

Part of switching over to Gen 4 was improving daily operation by locking down the extruder and the build environment. Going to the Mk.6 Stepstruder was already in progress but I really needed to ditch the difficult-to-use but trendy Automatic Build Platform for the Heated Build Platform (HBP). It was great for making kid’s favors at a Maker Faire but a real PITA for complex or experimental objects.

After some decent experiments with the Mk.7 (more on that later), I decided to try the 0.3mm head and 1.8mm plastic on the Mk.6 after the success with the 0.4mm head and 3mm ABS.

It works, but not well enough to actually print. The drop from 3mm to 1.8mm plastic, almost %50, should have worked well with the drop from 0.4 to 0.3 but the extruder doesn’t want to extrude. There was some talk on the makerbot list that black 1.8mm plastic required higher temps, those were red-lined by the software, so I did some measuring on my own.

Back in the early days, getting your print temperature correct was one step from ritual magic. That seemed likely, so I decided to repeat some early tests and wire up second and third sensors to run in parallel with the default sensors.

With these, I collected some data and made some graphs. The sensor tips were put as close to the MakerBot sensors as possible and I waited as long as seemed reasonable for the temperature adjustments to stabilize after a change.

  • built-in sensor that ReplicatorG software reads
  • Fluke 88V temp sensor with temperature probe. Not a cheap device but the readout is 0.1C and it’s fast
  • $20 BBQ grill cooking thermometer. Cheap, easy to use, but I think their goal is to make sure I don’t kill someone with undercooked poultry.

The short answer is this — the replicator is reading at least 10C lower than anything else, so I need to run with much hotter temps than are required by the instructions.

(The images are hosted on flickr for easier commentary)

Mk.6 tests:

Mk.6 with software 0033 (recent tree build)

Mk.6 with software 0029 (distributed)

HBP tests:

HBP with software 0033

HBP with software 0029

2011/11/15

cupcake + gen 4 + hbp + mk7 + 0027alpha ==> works!

Filed under: MakerBot — jet @ 13:51

Well, it’s working, and quite nicely. I don’t have the print range of a TOM, but I have quality, and that’s what I was after.

The trick to getting it all working was replacing the Z stepper that shipped with Cupcake #235 and replacing it with a more powerful one from Lin Engineering (which required a new metric pulley from SDPSI). The Z-table is now quite zippy and does not stall like the old one did.

Photos and parts lists to be posted everything’s a scattered mess in the aftermath of Pittsburgh MiniMaker Faire, the lasersaur build, fixing my mom’s laptop, and a thousand other papercuts.

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