Category: Uncategorized

Fixing the CNC’s rounding of corners.

There have been some troubles with the CNC not following Gcode paths exactly and rounding corners.

In this first picture of the Mach4 screen you can see the green lines which are the path the CNC should follow, and the white lines which are the path the CNC actually followed. (ignore the blue lines)

The problem is the CNC is rounding over the outer corners. This is a result of the CNC trying to move faster than it can manage. The max speed of our CNC is 200 inches per minute. In the above picture it is trying to cut at 150 IPM and can not handle that speed on the corners so it rounds them, which can ruin the piece. Even though the CNC can go faster in a straight line it can’t change directions that fast.

The solution is to use a slower feed rate. But this can greatly increase cut times and other issues such as tool dulling and excess heat.

Fusion360 has a solution called “Feed Optimization”. What it will do is reduce the speed in just the corners to 25% of the feed rate. In this example it reduces the corner feed speed to 37.5 IPM.

In this next picture you can see the white line of the actual cut path looks identical to the green Gcode path with Feed Optimization turned on.

The Feed Optimization setting is found on the 4th tab (labelled Passes) of the Operations Dialog when you are in the Manufacture workspace.

In the bottom of this picture you can see the checkbox to turn it on. The defaults should be fine and will reduce your corner speeds to 25%. This only adds a small amount of extra time to the cut.

This project was set to 100 inches per minute so Feed Optimization reduced the corner speed to 25 IPM.

Mouse over each setting for an explanation of what it controls if you would like to fine tune even more from the defaults.

Tool organizer in 3D printing

After the expansion, 3D printing ended up adjacent to a concrete wall that the landlord does not want us boring holes in. That means we can’t hang the tools up like I did before.

But I’ve always liked the desktop tool caddies that Ray made for electronics anyway. So, I knocked up a simple design and asked for volunteers to build it. Bob came through, and even finished it in a cool purple color, buffed to a nice shine. I almost hated to put screws in it!

But, last night, I finally got around to it. Thanks again Bob!

And yes, that’s a new caliper. Please leave it in 3D printing!

Call for Burners / Makers / Artists: DIY Burner Fashion Week

AMT is putting together a week of workshops focused on Burner Fashion July 23rd -29th.
Current Workshops Ideas include:
  • LED Fairy Wings
  • Leather Feathers
  • TuTu Good (epic tutu making)
  • Laser Cutting Faux Fur
  • “Help me finish this…” a project completion lab
AMT has:
  • Large laser cutter
  • Classroom space to teach programming etc
  • A full textiles studio
  • Electronics Lab
  • 3D Printing
  • Woodworking and more
If you are interested in doing a workshop for the DIY Burner Fashion Week email as much of the following information to [email protected]:
  • Possible Dates of the workshop (between 6-23 to 6-29)
  • Title of the workshop
  • Description of what folks will make (I can help write that if needed)
  • Description of materials needed (stuff people need to bring)
  • Description of materials provided
  • Description of needed skills (like if people should have basic sewing skills)
  • Duration of workshop
  • Cost to attendees
  • Link to a picture or pictures if you have them.
Teachers can charge for their workshops but we would like to keep them affordable too. We can work with you to develop an affordable offering. Instructors are paid out 1 week after the workshop via ETF or Paypal or Cash. Instructors making more than 400 will require a W9.
AMT can also provide some materials and or access to discounted or free materials. Go up-cycling.

The Vorpal Combat Hexapod

I demonstrated this fun robot at the last BoxBots build night and our general meeting last Thursday. Since then a few folks have asked questions so I thought I would post more detail.

The Vorpal Combat Hexapod is the subject of a Kickstarter campaign I discovered a few weeks ago. I was impressed and decided to back the project. I had a few questions so I contacted the designer, Steve Pendergrast. Then I had a few suggestions and before long we had a rich correspondence. I spent quite a bit more time than I’d expected to, offering thoughts for his wiki, design suggestions, etc.

Steve appreciated my feedback and offered to send me a completed robot if I would promise to demonstrate it for our membership. The robot you see in the photos was made by Steve, not me. Mine will be forthcoming!

You can read the official description on the Kickstarter page and project wiki. Here are my own thoughts and a few of the reasons I like the project so much.

It’s cool!

It has to be to get the kids interested; something that Ray has always understood with BoxBots. While BoxBots offers the thrill of destructive combat, the hexapod offers spidery, insect-ish, crawly coolness with interactive games and programming challenges.

It’s a fun toy

Straight away, this robot offers lot of play value. There are four walk modes, four dance modes, four fight modes, and a built-in record/playback function. To get them interested in the advanced possibilities, you have to get them hooked first. Don’t be intimidated by that array of buttons. At the Boxbots build night, the kids all picked it up very quickly. I couldn’t get the controller out of their hands.

It’s open-source

The circuitry, firmware, and plastic parts are already published. A lot of crowd-funded projects promise release only after funding, and some only publish the STL files, which can be very difficult to edit. Steve has provided the full CAD source (designed in OnShape).

Easy to Accessorize

The Joust and Capture-the-flag games use special accessories that fasten to a standard mount on the robot’s nose. This simplifies add-on design since there’s no need to modify the robot frame. There are also magnets around the perimeter, encouraging fun cosmetic add-ons like eyes and nametags.

Off-the-shelf electronic components

There are no custom circuit boards here. It’s built with two Arduino Nano boards, two Bluetooth boards, a servo controller, buzzer, pot, micro-SD adapter, two pushbutton boards, inexpensive servos, etc. This stuff is all available online if you want to source your own parts. If you’re an Arduino geek, it will all look familiar.

No Soldering!

I think every kid should learn how to use a soldering iron in school, but for some it remains an intimidating barrier. In the hexapod, everything’s connected with push-on jumper wires. (If you source your own parts you will probably have to solder the battery case and switches, since these seldom have matching connectors.)

Scratch programming interface

The controller and robot firmware is written in Arduino’s C-like language, but the robot also supports a beginner-friendly drag-and-drop programming interface built with MIT’s Scratch system. I confess, I haven’t investigated this feature yet, but I’ve been curious about drag-and-drop programming paradigms for years. My first programs were stored on punched cards. Finally, I have an opportunity to see how today’s cool kids learn programming!

It’s 3D printed

The parts print without support, and work fine at low-resolution. You’ll want to get your own spool of filament so you have the color available for replacement parts. Any of our printers will work. I’ve had good luck so far with PLA, but Steve recommends more flexible materials like PETG or ABS.

Anyway, enough gushing. I do not have any financial interest in the project. I just like to encourage a good idea when I see one. The Kickstarter campaign just reached its goal a few days ago, so it’s definitely going to be funded. If you’d like to back the Kickstarter or learn more, here’s the link. You’ll have to act fast; there are only a few days left. (Full disclosure: I do get referral perks if you use this link.) Remember that you always assume some risk with crowd-funding. I’ll make no guarantees, but I’m satisfied that Steve is serious about the project and is no scammer.

Click here for the Hexapod Kickstarter campaign.

If you’d like to see this robot in person, contact me on Slack. I’ll try to arrange a demo.