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Ok, heres my first stupid question of the year ... What is a die grinder?

I was over to the local tool store over the holidays and there’s a gadget for sale there called a “die grinder”. What would this gadget be used for? The only die I can think of is from the “tap and die” duo, you know the things you use if you want to cut pipe threads on bare pipe, the die used for cutting external threads I think. I don’t see a reason why I’d want to grind that kind of die. Either it cuts the threads or it doesn’t. I can’t see that grinding on it would help.

I know I’m showing my ignorance. What else is new? So help me out. A 'lil Car Talk education please? What the heck is a die grinder and what would motivate someone to want to grind on a die anyways?

There are straight and angled die grinders. These are tools where different cutting/sanding/shaping attachments can be used. If you want to port and polish heads/manifolds use a die grinder with cutters and polishers. If you want to cut material a die grinder can be used with a cut-off wheel. If you want to sand a die grinder can be used with small sanding discs/drums.


@GeorgeSanJose…I know I’m showing my ignorance. …
Dont worry, ignorance is simply not having knowledge. Will Rogers stated “everybody is ignorant, only on different subjects.”

Its an air or electric tool that rotates an abrasive disc, carbide burr or other type of cutting tool. Tire shops use them to patch the inside of a tire, body shops for gringing metal. Body shop also put rubber wheels on them and remove vinyl decals or old adhesive.

You cannot drill with them since they are not geared as they stall easily. they are simple air vane motors.

Die grinders can also be used to lightly modify metal stamping dies and also plastic injection molding dies to name two more. You could use one to sharpen an ax or a lawnmower blade.

It’s like a Dremel tool, but usually compressed air-powered. It is a rotary tool that spins about 25,000 RPM, and you can get all kinds of little sanding discs, grinding bits and cutting burrs that will fit in it.

A die grinder can be either pneumatic or electric. A Dremel tool is an example of a small electric die grinder. Here are a few others.

Yeah its like a big dremel. When I worked in the truck plant, they were used with a wire brush to clean the molding dies for rubber tires. So general surface cleaning, polishing, or grinding on either flat or contoured surfaces.

Thanks everybody, that is all helpful and a good explanation. So a die grinder – while it can actually be used to grind on and modify the kind of dies that would be used to stamp out metal parts or plastic molds say – it can be used as a general metal working tool, sort of like a combination rotory cutter, sander, buffer tool would be for wood. I can see that would prove very helpful for otherwise time consuming and difficult metal working tasks.

On other question on this subject. I see references to the term “die cast” from time to time. Like there’s a magazine at the bookstore about die cast toy cars. What kind of die is that a reference to? Are these toy cars stamped out? I always thought those toy cars or other die cast parts were made by pouring molten metal into a mold of some kind.

Die cast means a molten material is poured into a mold or die to create it’s shape once it cools.


One of the controlling unions at the auto plants used to be the ‘tool and die makers’ union, they were responsible for working on the stamping and molding machinery. Bet they used some ‘die grinders’.

Google is your friend …