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CAD Things…

Stand

I recently had to design a simple cabinet to serve as a stand for a mill/lathe. I thought about pulling out some rulers and triangles (yes, I used to actually do drafting with pencils and paper) but instead I decided to try using OpenSCAD.

Stand

I used specific colors in my design, of course when you actually render a thing in OpenSCAD the color goes away, but you can export the different views just fine without rendering. Here are the various view of the thing. Oh, since OpenSCAD is a “unit-less” thing which mostly outputs in millimeters (at least for STL files) I just assumed the units were inches.

Stand

I used the OpenSCAD “scale” feature to scale up the thing by 25.4 times in each direction, which means my 1 millimeter became 1 inch.

Stand

But in a real drawing you plan to hand to someone you need dimensions for things. While there’s been some experimentation in adding them, there just doesn’t seem to be an easy way to show dimensions of things in OpenSCAD. I resorted to printing out paper and marking it up… with a pencil.

Stand

I probably need to learn how to use FreeCAD for this sort of thing. I’m sure I can easily add dimensions with it. One of the really interesting things about FreeCAD is that it has an OpenSCAD Module. You can import a CSG file which you’ve exported from OpenSCAD, and you can just open .scad files as well.

Much more to explore here… stay tuned!

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Adjustable Rectangular Mount

Adjustable Rectangular Mount v1

I finally got around to creating a parametric version of the 3D printed mount I’ve been using for the past few years. Typically I’d just open a previously designed thing in OpenSCAD, make some adjustments, and export an STL to print. Eventually I realized that I should just create a bunch of variables so I can easily just make minor adjustments each time and not have to do a bunch of find & replace operations.

The result is Adjustable Rectangular Mount v1 which you can find on Thingiverse and Youmagine.

It’s a work in progress, and it still needs some tweaking, but I figured it was worth releasing to the world. (Hey, make it better if you can!) It doesn’t work for all sizes and configurations, but for most of my needs, it’s good enough.

Adjustable Rectangular Mount v1

I should probably do more research on how to improve things by reading through other OpenSCAD code, but as mentioned, you’ve gotta start somewhere. I’ll probably be using this one quite a bit in the future, and I’ll update it as I can.

This mount specifically expects that you can use screws (or bolts) to mount it to a surface you can screw into or drill through. I also often add some double-sided foam tape to the inside of the mount and stick it directly to the object being mounted.

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Screw/Bolt Diameters

Borrowing a bit from our friends at Bolt Depot, their chart showing US Machine Screw Diameters is helpful, but often I’m designing with Metric units (or a unit-less system that outputs in millimeters) and I need to convert Imperial units to mm. (I tend to do a lot of work using OpenSCAD and Inkscape for 3D printing.)

The chart below allows me to specify screws and bolts and then design holes that will work. For instance, I used a lot of #4 screws, and the chart tells me I need a hole diameter of approximately 2.794mm. Handy!

Size Thread Diameter
Decimal Nearest Fractional Metric
#0 0.06″ 1/16″ 1.524mm
#1 0.07″ 5/64″ 1.778mm
#2 0.08″ 3/32″ 2.032mm
#3 0.09″ 7/64″ 2.286mm
#4 0.11″ 7/64″ 2.794mm
#5 0.12″ 1/8″ 3.048mm
#6 0.13″ 9/64″ 3.302mm
#8 0.16″ 5/32″ 4.046mm
#10 0.19″ 3/16″ 4.826mm
#12 0.21″ 7/32″ 5.334mm
#14 0.24″ 1/4″ 6.096mm

See Also: Millimeters, Inches, Fraction, Decimals

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How to cut Zip Ties

How to cut Zip Ties

I had to make a short illustrated guide showing how to properly cut zip ties to avoid damage and injury, so I figured I should share it here as well.

When using zip ties care must be taken in cutting off the excess ends. To cut the ends off properly, we should use the right tool. Do not attempt to cut the zip tie ends with a knife or scissors, instead we will use a diagonal cutter, typically used for electronics work.

How to cut Zip Ties

The cutter we use is the Hakko CHP-170 Micro Soft Wire Cutter. These can be purchased from Amazon and other online shops as well as local stores. Other cutters can be used, but you should look for fine point flush cutters that are meant to cut small things.

How to cut Zip Ties

Once you put a zip tie on something you’ll have an end sticking out which needs to be trimmed shorter. Depending on the application you may be able to leave the longer end on, but for some specific purposes cutting them off makes sense. (One example where leaving them longer could cause issues if there were chance of eye injury caused by the end of a zip tie.)

In the photo above we see the start of the incorrect method of cutting off a zip tie end. Using this method will result in a sharp edge.

How to cut Zip Ties

Here’s a zip tie cut incorrectly which now has a sharp edge. The short piece of plastic is much more rigid than the longer piece which has some flex to it. We’ve effectively made a small blade.

How to cut Zip Ties

This one is even worse! We’ve now got a sharpened edge with a point. The edge of this zip tie can cut through fabric and even skin. We usually want to avoid damage and injuries. (Of course if you want to use zip ties as weapons, you can stop reading now.)

How to cut Zip Ties

Here is the correct way to trim the excess from a zip tie. Hold the cutter as close as you can to the head of the zip tie, and cut off the end. (Obviously you should start with this cut and skip the steps where I cut the zip tie end into a blade… I forgot to get a photo of cutting a long one for this step!)

How to cut Zip Ties

Get your cutter nice and flush against the head of the zip tie. Make sure there’s no excess sticking out before you cut it.

How to cut Zip Ties

Here is the result of properly trimming a zip tie. There is no excess to cause injury or damage. Consider this safe(r).

You should be able to run your finger over the head of the zip tie where you cut off the excess and it should be smooth. You should not feel any sharp edge. If you do feel a sharp edge, try the trim again, and if that doesn’t work, replace the zip tie with a new one and trim it properly.

How to cut Zip Ties

I hope you found this short guide to properly cutting zip ties useful. Let’s all be careful out there!

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Time Lapse Bot 3.5 (and 4.5?)

MMS WebCam

It’s been way too long since I posted anything about the Time Lapse Bot project. Here’s some good background info, if needed.

Time Lapse Bot 3, which I haven’t written about since 2011 (or maybe 2012) has seen a few upgrades. Don’t worry, it’s still running an ancient PowerBook G4 (how, I don’t even know) but we long ago upgraded to a Logitech C910 USB camera. We then added a long gooseneck to allow for easy adjust-ability. And finally, it’s also known as the Milwaukee Makerspace Webcam, and it published views of Milwaukee Makerspace at http://mkemake.us/webcam

But really, Time Lapse Bot 3 hasn’t changed very much in the past few years… probably because I’ve been working on Time Lapse Bot 4, which uses a Raspberry Pi.

tlbot4

Time Lapse Bot 4.01 made an appearance at Maker Faire Milwaukee in 2016, using a completely hacked together frame on one of my old rolling chair bases, and it worked for the weekend, but I’ve got plans… I’ve got plans.

I’ve made a lot of progress with software, and picamera is something I highly recommend! I’ve also got TLBot4 automagically uploading to a server, just like the Milwaukee Makerspace Webcam (running EvoCam, which may be dead now, as the web site of the developer has gone AWOL) and it’s also doing the daily videos compiled from the still images. I’m 90% happy with the software… I mean, the last 10% is the hardest, right?

I’m also working on a new physical build of Time Lapse Bot 4, which will feature many mounting solutions, and an interchangeable wide angle lens for capturing crowds.

Hopefully I can get TLBot 4 up and running for an event in the next few months, but in the meantime, I’ll be testing it in my workshop. (And hey, it’s offline now, so what the heck!?)

Also, I used the knowledge and experience I’ve gained (especially from picamera) to create part of a museum exhibit that has been running trouble-free (knock on HDPE!) since November. Huzzah!