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Tips and Tricks for Using an 80 Lower Jig

For how much we talk up the venerable 80% Lower Jig, you’d think the machine does all the work for – and it largely does! But there are still some tips and tricks for using an 80 Lower Jig the right way. These best practices can make the difference between a frustrating build that fails, and a completed 80% Lower that’s built to exact tolerances with a lovely finish. Let’s begin!


#1: Get a Good Bench and Vise

Your 80% Lower Jig is precise, but to keep that precision while drilling and milling, you’ll need to have a good workstation. A sturdy vice and bench will keep your 80 Lower Jig and tooling seated and secure. Having your 80% lower jig move even a fraction of an inch while machining could have disastrous – even dangerous – results.


#2: Inspect and Clean Your 80 Lower Jig and 80 Lower

Your 80 lower and jig will ship as brand-new, packaged products, but you should still inspect each component and give each a good wipe-down before you begin working. Imperfections in manufacturing are incredibly rare, but transit and even careless handling can result in a chipped, scraped, or cracked lower or jig.


#3: Secure your 80% Lower Properly

We’re working with incredibly tight tolerances while we machine our 80% lower. Having your lower seated incorrectly, or having a bolt torqued incorrectly, could result in an 80% Lower that isn’t machined to the correct specs.


When seating your lower in your jig, inspect for any debris that could cause your lower to be seated incorrectly. When tightening your bolts, torque them in sequence, opposite from each other. Do not over-torque the bolts – only tighten them enough to ensure the lower won’t move.


#4: Buy Masking Tape

When you machine your 80% lower, you’ll be putting some fast-spinning tooling against bare metal. You’ll also be working against the reinforced steel of your 80% jig. It’s a matter of safety and simple insurance to cover your workspace – all exposed metal not being machined – with masking tape.


This will help prevent marring or damaging your 80% lower or jig while with any tooling or debris you work.


#5: Clean and lubricate while you work

You’ll be removing large amounts of aluminum alloy while you drill and mill your 80% lower. All that debris will quickly interfere with your workspace. This debris must be cleaned while you work. It’s a good idea to invest in some canned air or have a compressor handy, to blow away debris.


Purchase some lubricating oil or machine oil and liberally coating your tooling, jig, and lower while you work. This will ensure your cuts are cleaner, and it’ll help keep your tooling cool and sharper, longer. It will also help reduce friction while drilling and machining, reducing the chance of mistakes or rough edges.


#6: Protect your eyes and hands

This should go without saying, but we feel compelled anyway: Buy some protective gloves and invest in some eye protection. Anyone operating a handheld router, drill, or drill press should be protecting their eyes and hands.


But you won’t be cutting wood or drilling into a kitchen table. You’ll be machining metal with other metal – danger is present. Protect yourself.


DISCLAIMER: If you are new to the world of DIY gun building, you likely have a lot of questions and rightfully so. It’s an area that has a lot of questions that, without the correct answers, could have some serious implications. At 80Lower Jigs, we are by no means providing this content on our website to serve as legal advice or legal counsel. We encourage each and every builder to perform their own research around their respective State laws as well as educating themselves on the Federal laws. When performing your own research, please be sure that you are getting your information from a reliable source.


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