Metal project: Key cutter/duplicator for a mini-lathe


My latest fabrication venture is this "key cutter/duplicator" attachment I made for my mini-lathe. The idea just popped into my head a few days ago so I had to run with it. First job was to see if any others were out there for inspiration. A search on the net turned up 0 home made key cutters! I was surprised by that! Maybe there are a few out there somewhere but I couldn't find any...

You can buy small machines starting around $100 up to thousands of dollars to cut keys but that's no fun! I was looking for a new project anyway so I set out and researched all I could find on how they work. Some of these machines actually reminded me of very small metal lathe in design so I knew this would be easy. (and it really was)

While my design changed a few times during the process, shown below is what I ended up with. It's made all from alumninum with a steel handle I formed from 1/4 hot rolled (might need to upgrade some of the sliding areas to brass later if it see's enough use or gets any wear)

I opted to build the main stand so it mounted to the lathe bed ways. Initially I was going to have it all attached to the cross slide but there wasn't enough room on mine to allow the dual cross slide table. The main support goes onto the bed very quickly with 2 cap screws to clamp it on. Then a small table slides on for the in/out movement with a set screw so I can never run the key clamp into the cutter. The "key clamp" piece that the keys are clamped into simply slides left and right in a groove.

The cutter is just something I had bought and never used. It's a 2 inch 100 tooth cutter from Harbor Freight part #42805, pack of 3 for $9.99 It is designed to cut plastic and soft materials up to brass so it works well. (most keys are made of plated brass)

I built an arbor shaft for the blade and it mounts in a 3/4 inch collet so it runs nice and true. The "follower" is made from a thin washer (I have since thinned it down more than shown for more accurate cuts) It's mounted on a metal rod that goes into a home made tool holder I had in my drawer. With this part on the cross slide, it makes it a breeze to line up the follower to the cutter position on the keys. In fact, the whole set up takes hardly no time to install and actually use.

While it may look a bit dangerous, it's really not bad, I've even added the handle so mine is safer! The blade has fine teeth so it's not too aggressive. It won't pull you in and fling you against the wall or anything. :D It even has that "key cutting machine" sound! It is a safe as a commercial built model. It runs at a slow RPM (a few hundred to guess) and you just work from the high areas down into the valleys. The key your cutting can never go any further into the blade than the follower allows. The deepest cut on these GM keys is .100 thousandths anyway so your not hogging out material by any means.

Today I cut my first key and it was a success! It works in the lock perfectly. (I did run a wire brush in a drill over the cuts to take any sharp spot off like they do when you get a key made at a store)

Part 2 (in a sense)
All of the above is fine for "duplicating" a key but you can't duplicate a worn out key. With proper depth and spacing keys (I have a set ordered a set for GM vehicles) and a key code book, I can take the 4 digit code from any GM lock and use those to produce a brand new key! I will probably update this post later when I get the keys I have ordered explaining that a bit more... Since I have a lot of antique cars & trucks, I'll be putting it to the test soon!

a.jpg b.jpg c.jpg d.jpg e.jpg f.jpg g.jpg h.jpg


Thanks! The last time I had the Chevy dealer "punch" keys for me using the code, they charged me $15 for 2 keys! (and I provided the key blanks!!!)

I ordered up a bunch of original type GM key blanks and will be making all new ones for my cars that need them. Both of my Impala's and the 71 Chevelle had new keys punched so they are good but the rest have worn keys. I'll pop out a lock on each of the others and make new ones using the codes.


Got a whole mess of GM keys! Best of all, I only paid .72 cents each! (with the shipping included) I bought 44 of them. Only bummer is they didn't have any J or K code keys.

Finding the octagon and round keys our Impala's had is a bit harder and cost over $2 per key best I could find.



Well Known Member
Supporting Member 1
Doggone Bob you're alright, just promise us one thing if you ever get bored making car keys that you're not gonna go big time and go to the other side and become a cat burglar and start cracking safes unless you think you'd look good in stripes.

Last edited: