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. Very few mistakes were made, if any, and I think the project is moving along very nicely now!

I’m continuing to assemble all the different components. I’m looking at how things fit together, and how simple I can make the assembly process.
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. This GRBL 1.1 shield was only $12 on ebay! It works great and it even came with 3 stepper motor drivers w/heatsinks.
Testing the nameplate light filter. I decided to make it in two parts to reduce the amount of supports I would need for the letters. For some reason I thought this notch on the left side would be needed, but I was wrong – I ended up reprinting this side after all these photos were taken.
The press fit PLA part is pretty good. It was tricky to make proper offset geometry because the nameplate model is made out of splines/Bézier curves – which can be notorious for being difficult to work with in certain ways.
Results of the nameplate light filter.
I also reprinted the whole front nameplate because my new pancake style Nema 17 steppr 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, and I’m very happy about that. I also increased the size of all the holes I originally was tapping, so that I can use heat-press threaded brass inserts now. All in all, everything has been a huge success!


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 –

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.

3D Printed Two-Tone Mastercam Logo

This 3D printed stamping die was made for a Mastercam trade show in Mexico. The regional sales manager wanted this piece so that he could demonstrably show that Mastercam has tools and features that are useful for Additive Manufacturing.

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.

Roughing out the CAD model

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

Here’s all the printed parts, besides the gears!
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…
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.