Two-stage carves, or roughing/detail carves, allow you to use two bits on the same project. This allows you to carve as much of the project as possible with a larger (roughing) bit and then swap in a smaller (detail) bit to finish intricate parts of your project.
There are many benefits to using the largest possible bit for carving the majority of your job instead of carving everything with the smallest bit. Using two bits can shorten the overall length of your carves. These types of carves also extend the life of small, delicate bits because these bits are only used to carve sections of the design that require a narrower bit diameter.
If you are using the z-probe and homing switches, running a successful two-stage carve is straight forward. The process will go something like this:
- Connect USB
- Setup project in Easel
- Home Machine (Machine > Home)
- Click Carve
- Probe Material to set z-axis work zero position
- Move to XY work zero position
- Click Carve
- When carve stops, change the bit (assume machine has moved)
- Re-Home Machine (Machine > Home)
- Click Carve
- Probe Material with the second bit to set z-axis work zero position
- USE LAST XY to have the same starting point as the roughing carve
Now let's take a look at how to set up your project in Easel!
In the top right corner of Easel, you’ll find your normal bit selection tool.
Your first bit should always be set to the largest possible bit size you can use to complete a project. In this case, we are going to use a .25” (¼”) bit to carve this sign. However, this large bit won’t carve some of the finer details.
This is where a two-stage carve comes in handy. Some of the objects are large enough to be carved with a wide bit, which minimizes your carving time, but there are still some parts that would be better carved with a small bit. Using the small bit to carve the entire project would take a lot of time. Additionally, subjecting delicate bits to this much use increases the likelihood that they could break.
Instead of using the small bit, we will carve as much of the design with the first, larger bit—the roughing bit—and then finish the project with the smaller—detail—bit.
To add the second bit, click the “+” next to the bit selection menu in the upper right corner of Easel. You can then select the detail bit.
When selecting your detail bit, it’s still important to select the largest possible bit you can use to complete a job. For this project, I could use a 1/32” bit, a 1/16” bit or a V Bit. A 1/8” bit is too large to carve all the necessary details.
To save time and minimize the risk of breaking my bit, I chose the 60° V Bit instead of the 1/32” bit. You will see both bits in the Easel toolbar now.
Let's take a look at what our toolpaths for this carve. You can check this by clicking the “Simulate” button.
For two-stage carves, the “Simulate” feature gives you two sets of toolpaths. The first set of toolpaths—indicated by the light blue toolpath lines and the red machine lines—are the paths that your roughing (larger) bit will take. Your machine will make these carves first, so make sure that you have the roughing bit in your collet before beginning your carve!
The second set of paths are indicated by the dark blue toolpaths and green machine lines. These are the paths your detail bit will make after the roughing paths are completed.
After simulating the job, we can see that all parts of the design will carve correctly. That’s great news!
Let’s start carving. Click the “Carve” button in the upper right corner of Easel to open the walkthrough.
In the “Choose Pass Type” section, you’ll see that there are two options: Roughing Pass and Detail Pass. As mentioned previously, we always want to start with the largest possible bit. In this case, that is the roughing path. Select “Roughing Pass” and click “Continue.”
You will be asked to confirm your bit size. Make sure that the bit selected here is the same as the one chosen for your first bit (in this case, the 1/4" bit). After checking to make sure you have the proper roughing bit installed in your machine’s spindle, click “Confirm Bit” to move through the rest of the process.
Go through the walkthrough and complete the first part of the carve with the roughing bit. Your machine will bring your spindle back to the home position.
This is the trickiest part of completing a two-stage carve. Turn off your spindle. In Easel, click the “Carve” button again to open the walkthrough. Use the machine controls to raise your Z-axis high enough to remove the roughing bit from the collet.
Once the bit is raised enough to remove it, use the machine controller to lock the motors.
Then, being careful not to move the spindle along the X-axis or Y-axis, remove the roughing bit from the collet and insert the correct detail bit.
Unlock your motors in the Easel machine controller and lower your Z-axis back down to the material. Zero your Z-axis the way you normally would for a carve.
If you are using the z-probe and homing switches, please follow the order of operations at the beginning of the article. It's not necessary to lock or unlock your motors if you have homing switches as you will re-home the machine after changing the bit.
In Easel, confirm that your cut settings (depth per pass, feed rate, etc.) are correct for the detail pass. If you are using custom cut settings, you need to change the settings to match the detail bit instead of the roughing pass bit. You risk breaking bits if you use the same cut settings for the detail bit that you used for the roughing bit. We are working on Easel enhancements that allow for separate settings for each bit, but for the time being, it must be done manually.
Once your machine is set up and the cut settings are confirmed, you're ready to continue carving! Go through the carve walkthrough again but this time select “detail bit” from the settings.
It's important to confirm that the roughing bit size and the detail bit size are correct. If your roughing bit size is not correct, the machine will not know how much of your design has been carved. Hit “Both bit sizes are correct” to continue.
Your machine will now carve the rest of your design. If everything was done correctly, the detail carve will successfully align with where your roughing bit left off.
The most common problem with two-stage carving is that the detail bit ends up carving on a slightly different path than the roughing path on X-Carve. (Carvey doesn't have this problem, thanks to the smart clamp's automatic homing). This is caused by the Y-axis or X-axis shifting slightly when exchanging the bits. Unfortunately, there is little that can be done to correct this except using the homing switches or practicing the bit exchange for future carves. It is a meticulous process, but if you can master your own technique, using two bits to complete your carves can save you a lot of time and extend the life of your smaller bits.
If you have any suggestions about this feature, or if something didn’t go the way you expected, please add it to our Forum thread about two-stage carves. Our Easel Developers appreciate your feedback as we work to improve Easel and make it easier for you to bring your ideas to life.