April Fools Day Video

I made a silly April Fools Day video for Mastercam with SketchyBot. It managed to get a few thousand views and around 100 shares on Social Media! You can see it here –

SketchyBot Week 2 Progress Report

This week I continued refining my design, verifying all my measurements, and testing how parts interacted with one another in real life during assembly.

I’m trying to look at my work critically with an eye for how to make the assembly process as simple as possible in future revisions. See what works, and what doesn’t.

I started off the week by switching the spare electronics Sketchbot started with out for some optimized components.

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New Micro Controller!

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I’ve switched to some simpler electronics for the project. I’m going to use a Metro Arduino Uno clone because it uses micro USB and has hardly anything I don’t need.

I found this GRBL 1.1 shield on ebay for only $12. It works great and came with three stepper motor drivers (plus heatsinks)!

Printing new parts – 

I finished printing the new Back Cover that I proposed in last week’s blog entry. I may want to backlight this with some RGB LED strip lighting, because I’ve realized how well the striated texture of a 3D printed part can defuse light.

In the future, I believe this could be printed without supports! I was very impressed that such a skinny part didn’t fall off the build plate.

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I reprinted the front nameplate because I sourced new pancake-style Nema 17 stepper motors didn’t need to intersect with the component anymore! This also means the holes for the stepper motor cables can be hidden from sight, which is awesome.

I also increased the diameter of all the through holes in this part.  I originally was threading holes on the PLA part, but I’m switching over to using heat-press threaded brass inserts.

Testing the nameplate light filter –

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Testing the nameplate light filter. I decided to split it in half to decrease the amount of supports the letters needed.

For some reason I thought a notch on the left side would be needed, but I was wrong. This left side was reprinted after all these photos were taken.

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The tolerances of this press-fit were really dailed in! At first I was worried about this, because the light filter CAD model is built through references to the nameplate through converted sketch geometry.

Ordinarily, this wouldn’t have been anything to worry about, but the nameplate utilized splines in the creation of it’s side profile geometry. Splines/bézier curves can be notoriously difficult to work with in certain ways – Solidworks does not handle offsetting splines elegantly!

It was quite a relief to get this part fitted without it breaking halfway into the nameplate. In the future I will want to marry these two pieces together into one dual-extruded object.

Alternatively, instead of dual-extruding a two-tone part, I could slice this part with varying infill density. That way a single extruder could potentially create a built in light filter. All things to try in the future!

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Here’s the results of the nameplate light filter, photographed in low light. Much better!

All in all, everything has been a huge success! Very few mistakes were made in this stretch of development, which is always nice.This project is moving along quite smoothly 🙂

Design Revisions Cont.

I just picked up a dual-extruder 3D printer, so I think I can make a front nameplate for Sketchybot that’s dual extruded instead of making that insert I proposed in my last post.

I imagine using black PLA everywhere but the areas where the text is – the text should be printed in transparent or white PLA.

Generating the different solid models required for this idea will be done by applying boolean operations to bodies comprised of extruded splines. This is going to torture my CPU – so that will be fun!

I also want to make a new Back Cover for the bot. The slotted laser cut acrylic sheet I originally designed was very difficult secure in place, and bending it into the correct shape with a heat gun was difficult by hand. It looked like this prior to being bent into shape-

I could heat the sheet in an oven and then place it onto a CNC-cut form, but that would be way too much effort for little return.

Instead, the new Back Cover will be entirely 3D printed. Pending any last minute changes, it should look like this –

Edit:
I will need to use threaded brass inserts to secure this Back Cover to the Side Plates, since I will not be able to hold a Nylock nut in place, while fastening everything together. I could inset the nuts inside hexagon cut-extrudes, but I’d be worried about such a feature rounding out.

Electronics Update

I finally got my 24V step-down converter wired up! I have since then installed the LED strip inside the 3D printed front name-plate. It looks like this –

From afar, the lights really wash out all the text… I’d like to avoid that.

Up close, or at a few particular angles, the text looks great – but I want it to always look great!

So I’m thinking that I’ll 3D print an insert that’ll slide inside the cavity in the front name-plate piece.

Here’s a short demonstration of what the part will look like in the assembly –

So hopefully this new component helps out. I’m going to print it of black PLA with a high shell-count and 40% infill, so most of the light shines through the text. If this works, my next step will be to sand down the front surface of the name-plate and spray some gloss paint on it. I’d probably mask off the letters for this process, but a quick test could determine if that’s truly necessary.

A new GRBL shield and some low profile stepper motors were ordered today! I’ll have those parts installed by Tuesday, I am just really hoping that I don’t need to modify GRBL firmware that much when I get the new board.

Prototyping Parts

To start things off, I got the CAD model exactly like how I wanted it, and then exported out all the STL & DXF files that I would need to start fabricating components.

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Roughing out the CAD model

I printed parts on a CR-10 and  Monoprice Maker Ultimate (Ultimaker knockoff)

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Printing….
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Here’s all the printed parts, besides the gears!
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I’m going to try laser cutting a piece of acrylic so that it bends like fabric across the backside of the electronics enclosure. We’ll see how it goes…
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Laser cutting the back back panel. This took 40 minutes to vector cut all those tiny slots!

Everything is starting to come together. The Etch A Sketch needs to be held a little tighter, but that will be fixed in the next round of changes.