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Common Router Bits

In car audio installation you will only ever really need 4 bits....

Straight/flute cutter This your general purpose bit that you will use for cutting rings etc. 1/4" is perfect for most things. The best investment you can make is to by a decent straight bit as it will cut cleaner and faster and last longer in mdf. On toms recommendation, I bought a Trend STC sprical upcuter. This is made of solid tungsten so will stay sharp longer.. and has un upward twisted sprial that draws the dust out of the grove. Fantastic cutter.
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Round Over Bit This is self explanatery really. This but rounds over edges nicely. It is guided by a ball bearing that runs along the edge. The amount of curve you get depends on how deep you run the cutter into the material. Use it for smoothing over sharp edges round speaker rings, port openings etc.

When stretching cloth over a speaker ring, I normaly round over the outside edge of the ring so that when you stretch the cloth over it, you dont have a sharp circle. Depends on the look you are going for really.

A cheap one is as good as any really.. if you can afford the extra, go for TCT (Tungsten carbide Tipped) probably about 9mm radius will do for most things

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Chamfer Bit Same as above really but basically a 45degree cutter. Used for beveling edges. Great for adding a nice detail around cut out windows panels. Again the deeper you plunge the cutter, the greater the bevel will be.

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Flushing bit This is a sraight cut bit but with a bearing that runs along a guide. This is great for making exact copys of baffles or trim bits etc.. Clamp the item to copy to another bit of wood.. then adjust the depth of the cutter so that the bearing will run along the edge of the item to copy. The cutter will follow the profile of the guide. Also great for cutting perfectly straight edges. Clamp a straight edge below the line you want to cut and wizz along with the router to make make an nice clean cut.

Also handy for opening out the speaker hole if you have stretched cloth over a ring and resined it on builds. drill/cut a hole that he bit can plunge through and use inside of the baffel ring as the guide.

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There are also many grades of bits. The most common ones are

HSS - High speed steel Hss cutter are the cheapest cutter made from treated steel. These initialy have a sharper cutting edge than any other, but will blunt the quickest. Hss shuold only be used on soft wood and will give a nicer finish compared to the others.

TCT - Tungsten Carbide Tipped These cutters have tungsten carbide coated cutting edges. These are much harder wearing so will stay sharp longer. These are a must for hard woods or man made woods such as chip board or mdf.

STC - Solid Tungsten Carbide These are milled from a solid block of tungsten carbide and are the strongest most hard wearing bits. These are recommend for pro users or CNC applications. These can also be re sharpened while TCT cutters will loose their coating if sharpened to many times. These are also the most expensive cutters but if you loose them a lot, will be cheaper in the long run.


It's worth noting that STC bits are also more fragile. Take your time using them and don't push them!