weight of router bit


Help Support UKworkshop.co.uk:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


11 Oct 2014
Reaction score
Any body here know how to decide what speed a certain router bit should be used at? I'm contemplating buying a large diameter 1/2" bit but my makita router does not have speed control.
The manual just gives a vague "match weight to speed" but no specifics.
Any weight / speed charts out there?
I'd prefer actual charts rather than seat of the pants "feel" :shock: :roll:
That's something I've never thought of, as Marcros said I've only ever considered the diameter of the bit.
You learn something every day.
Thats annoying :shock:
The cutter I was going to buy is rated for only half the makita speed.
I dont mind pushing the envelope a little bit, but I'm not going to push it while I'm holding a sharp knife.
back to the shopping list (hammer) (hammer) (hammer)
Thanks very much.
A router bit has a mark that indicates the minimum amount of shank that should always be clamped and also the maximum rated speed not to be exceeded. Both properties are specific to each router bit to ensure safe operation e.g. Trend mark their bits on each shaft, others put them in easily lost instruction sheets.

Initially I couldn't see the point of having a variable speed control but I now realise that the speed only needs to be turned up if it's required (mostly it isn't) and the safe operation speed can be adhered to - (obviously) the dice are loaded more in your favour if you consider both of these parameters.
its a big makita and it spins at 22,000 rpm. a bigger bit will take more power and on an underpowered router just might work. But mine will spin any damn thing I put in it so its too big to chance.
I'm now looking for a variable speed controller. In the USA they are 20 dollars or less. I cant find in the UK except for an amazon item but thats only 8 amps and i need 15.
There are mechanical ones that fit on your router, don't have a link sorry.
It's just a knob on a bracket with a flexible shaft that has an end on it that you fix to the dial on your router.
In that case it won't work on your's, you will need a VFD (variable frequency drive) they can be expensive or as cheap as chips on e-bay.
My 1/4" Makita has six speeds: 1 = 10,000, 2 = 12,000, 3 = 17,000, 4 = 22,000, 5 = 27,000 and 6 = 30,000.

Router bits e.g. Trend have a marked max RPM e.g. a smaller bit might be limited to 28,000 - so setting 5 gives a bit of safety. Perhaps the quoted speed drops a bit but it's wise to play it safe? A bigger bit e.g. 31mm shaped bit will be rated at a lower speed e.g. 18,000 - so setting 3 is a good choice.

With a lower speed there is less risk of burn or the bit over heating. There are 15 or 20 amp router speed controllers e.g. on Amazon - but they are not particularly cheap and don't control the speed linearly according to the reviews.

A 1/2" diameter router bit might still be rated at 28,000 rpm - so matched to a router's output if full load speed drops a bit. Problems come when the diameter is much bigger - like a lathe the appropriate speed to maintain a linear cutting speed quickly drops.
Single phase too single phase VFD's are about £50.00 that will have infinite control over router speed, some more expensive versions have constant speed control so no matter what the load the speed will be constant.
sunnybob":25x2egyo said:
I'm now looking for a variable speed controller. In the USA they are 20 dollars or less. I cant find in the UK except for an amazon item but thats only 8 amps and i need 15.

Is this just for the router?

How many HP is it? 2HP is 1500 watts = only 6.25 amps
I'm not prepared to spend 50 quid plus on a speed controller for just one cutter, which in itself is another 50 quid.
ta, but I've changed my mind.