Modulus Arms SpeedMill™
Please Note: The Modulus Arms Router Jig Extreme™ requires the use of one of our SpeedMill™ end mills.
The Modulus Arms SpeedMill™ harnesses the power of a handheld router to produce an exceptionally smooth finish with no prior experience required. The SpeedMill™ utilizes a thermal fit tool coupler that attaches directly to your router. This prevents the end mill from coming loose from the collet during milling, which is a common issue with other types of jigs.
The steel coupler portion of the 80% lower jig tool is heated, causing it to expand and accept a 5/16" diameter solid carbide end mill, which is specifically designed for router based 80% lower milling. The end mill is thermal fit into the tool holder so it will not slip out during use. The end mill portion of the SpeedMill™ can be replaced by the customer by heating the steel coupler with a torch.
The length of the carbide end mill portion of the SpeedMill™ has been reduced to just 1.5 inches. This is under half the length of any other type of end mills designed for router based milling in an 80% lower jig. This reduced length results in an ultra-rigid milling tool that produces a mirror finish in record setting time.
Confirm SpeedMill Type
We strongly recommend all customers to only use our proprietary end mill, the Modulus Arms SpeedMill™ with our 80 lower jig.
Please see the chart below for which routers we recommend to use with our corresponding SpeedMill™ versions (there are 4). You can also pick up a Tool Kit if you want spare tools.
If your router is not on any of the lists, then it is not compatible with our products and we do not recommend using it to complete an 80 lower with Router Jig Extreme™. Please note that all routers that use V4 will need the Large Router Plate. 
*Satisfaction Guarantee
Our products are protected by multiple issued and pending US Patents.
It’s possible that some, very rare and oddly shaped non-milspec AR designs will not fit this jig. In the unlikely event that your 80 lower doesn’t fit you may return the jig for a full refund or consider buying one of our 80% lower receivers instead!
