Check for high feed rates or cut-per-pass depths.
Generally speaking, feed rates should not be over 50 inch/min. Easel has recommended settings for feed rates based on your bit size and material type.
You can review these settings before carving by clicking "Cut Settings" in the upper right corner of Easel.
Try reducing the feed rate (inch/min) by 25% and attempt your job again. In the "Cut Settings" option, click "Custom" to adjust your feed rate.
Your "depth per pass" settings can also cause bits to break. As a rule, your depth per pass should never exceed half of your bit's cutting diameter. For instance, a bit with a 1/8" (.125") cutting diameter should have a maximum depth per pass of .0625" per pass.
Some harder materials, such as aluminum and PCB circuit boards, require a more conservative depth per pass setting. Easel will make this adjustment when you select your material from the material menu. If your material is not listed on the materials menu, selecta material with a similar density.
Use a larger bit.
As a rule, always use the largest possible bit your design will allow. Easel will let you know when a bit is too large for carving part of your project.
If there are no red parts on your 3D preview, try playing with the "Bit Size" settings in the upper right corner of Easel. Select a larger bit than the one you're using and see if you get any red parts in the preview pane, indicating the bit is too large for your project. If you can successfully complete the carve with a larger bit, use the larger bit.
We have a beta version of Easel in place that allows you to do two-stage cuts: a roughing pass that removes large amounts of material, followed by a detail pass with a smaller bit for intricate carves. This allows you to switch out the bit midway through your job so your smallest bit doesn't do the majority of the work, making it prone to breaking. You can also save a lot of time using this method.
Click here to request access and learn more about this beta feature.