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How to make a Giant Connect 4 on your LongMill

Hey everyone. We’re excited to share another really awesome project tutorial for your LongMill! If you want to check out the last project we did, please check out our article Make your own CNC workholding with your LongMill!

For all of the project files, gcode, and DXFs, please check to download.

For the Onshape project, see

Parts and Materials:

All you need for this project is a sheet of 1/2″ plywood and a 1/8″ end mill. Everything fits and slots together with friction and some persuasion with a mallet. If you want to use a different size material and modify the dimensions of the design, we’ve included a few variables that can be adjusted in Onshape for your specific materials.

By default, we made it so that the thickness of the wood is 0.5in, the thickness of each puck is 0.5in, and the diameter of the pucks are 3 inches in diameter. You can change the number in the variable to change the dimensions. If you use the pre-made project files and gcode, we’re assuming your material is 0.5in. Although most 0.5in plywood will work, if you want materials to fit perfectly, you can measure the thickness of your material with calipers, input that as a variable, and all of the slotting surfaces will automatically scale up or down, with additional clearance added in key areas to slot things smoothly.

Since the LongMill 30×30 is our most popular size, we’ve made everything work on the 30×30 size. Below is a diagram of how we broke down a 4×8 plywood sheet into sections for the LongMill.

Onshape offers a free, hobby and education use license that offers the full functionality of their program on the cloud, with the exception that all projects made on the free plan are public and searchable. This means that derivatives of this design will also be available to the public.

To modify designs, you will need to create an account on Onshape and duplicate/copy a new version to make changes. A few other notes:

  • When importing your DXF into a CAM program like Carbide Create or Vectric, please note that if they are coming out the wrong size, you may need to change your project units. I’ve found that setting the project units to inches usually works the best. Alternatively, you can scale them to the right size.
  • DXFs from Onshape are not usually joined, so you may need to use a “join vector” tool before creating toolpaths.

Most CNC users will likely want to export all of the parts as DXFs. This is a very easy process. Simply right-click the side of the model you wish to export the face of and “Export as DXF/DWG”. Then import the vectors into the CAM software.

For these projects, we used a 1/8″ end mill. Since we’re working with plywood, a down-cut end mill will work well, but a compression bit might work even better. You should be able to use any 1/8″ bit, but if you want to buy some from us, you can find them below:

General Cut Settings

If you are making your own gcode, you can adjust your speeds and feed accordingly. The gcode made for this project is fairly conservative and should work for pretty much any type of wood. You can increase and decrease your feeds and speeds using Feedrate Overrides in gSender or most feature filled gcode sender.

Here are some tips that might help otherwise.

  • Use ramping to help smooth out your cut. There are many small parts to this project that are prone to flying out. Ramping reduces the cutting loads when moving between each pass and prevents the part from breaking or shifting.
  • Use a smaller final pass. In some CAM software, you can set a final pass. This is the thickness of the last pass. By making the last pass smaller, you can prevent your part from flying out as the cutting loads are smaller.

This project was made with VCarve Pro, which has all these features. If you’re looking for free CAM software that can handle 2D DXFs for this project, I’d recommend Carbide Create as an excellent option.


Start by cutting all of the parts out. You should end up with a couple of big parts and a bunch of small parts that keep all the big parts together. Here are a few exploded views to help out, but overall, the assembly can be found in the instructions.

A few notes:

  • Using some scrap wood to help direct your mallet blows will help keep your parts from breaking.
  • Putting in the “pirate teeth” on the one side first before assembling the second half, rather than putting both big sheets on first and putting the teeth on after, rather the way it was shown in the video may help keep things from shifting when assembling the two halves together. This will also help protect the tabs from breaking from the other side as well.
  • We’ve made some changes to the design between the video and the final public version to help things fit better and make tweaks. If you have some differences in your design, don’t worry too much as you’ll probably have the better version! However, if you run into any issues, feel free to reach out.

I hope everyone enjoys this new project. Stay tuned for new projects coming down the pipeline and make sure to subscribe to our Youtube!