Router Depth

[Cain]

What's the rule of thumb for depth of cut when cutting dados (or just about any cut for that matter) with a straight bit with a router? It seems that I remember reading my router manual a few years ago that you should only cut 1/4" at a time. Is that correct?

I have a router that only accepts 1/4" shank bits. For future reference, could you cut deeper with each pass with 1/2" shank bits on a 1/2" collet router? (I've got my eye on the Hitachi router kit currently on sale at Amazon.)

While waiting for my Freud dado set to get here, I've decided to go ahead with a current project by cutting dados with my router. Some of the dados call for depth of 1/2", but I don't want to go too deep too fast if it's not appropriate.

[jackellis]

I just cut some dados in 2x4s with the Hitachi using a 1/2" collet bit at 1/2" depth and it worked quite well. However, with a 1/4" collet, I would make multiple passes. For one thing, the shank of a 1/4" bit will flex. For another, the stress of making a cut that size might cause a 1/4" bit to fail.

The Hitachi is big and powerful. The difference between it and the Ryobi and Craftsman routers I've used before is like night and day.

[vaking]

I would be very cautious making a cut deeper than 1/4" even on 1/2" shank and if you have a 1/4" shank bit I would reduce the depth of cut further depending on the diameter of the bit. 1/4" shank bits flex and brake and plus they are small so they get hot if you cut too deep and start burning wood. It is better to reduce depth of cut than speed or feed rate.
Hitachi makes great routers; M12V lives in my table, KM12SC is my hand-held router. KM12VC would be good all-around kit.

[Cain]

Unfortunately, it looks like I waited too long on the Amazon deal. It was in my inbox yesterday, but I didn't pull the trigger. Wish I did.

[LarryG]

A quarter inch per pass is a good rule of thumb, yes. Although there are lots of variables to consider. Router horsepower, bit diameter, bit type, wood density, feed rate, etc.

Router guru Pat Warner says not to cut more than the equivalent of 1/4" x 1/4". With a 1/2" dia bit, that would mean 1/8" deep per pass. I'll confess to regularly cheating on this limit ... at 3/4" and above I'll reduce the cut depth to less than 1/4" but for bits smaller than that I generally don't.

One thing I virtually always do is take the cut to about 90-95% of its final size, using however many passes are required to get there, and then make one last pass to clean it up.

[ejs1097]

I usually do 1/8" for most bits even non straight bits. It might take longer but if the bit tears into the wood once and ruins it, you'll wish you took less the first time.

[LCHIEN]

My 2 cents
the 1/4" bit I would not take more than about 1/8" because if you look at it from the end with the flutes and all its cross section is not very strong and they are easily broken, esp. the spiral upcut straight bits.

I think with the 1/2" dia bit 1/8" deep cut is probably a safe bet, you are cutting twice as much material per pass, if you try and cut as much as 1/4" it will be 4 times the cut as the 1/4" recommendation of 1/8". I'd feel more comfortable cutting 1/4" with a 1/2" bit if it also had a 1/2" shank.

[JimD]

Accuracy suffers when you try to push things. Like Larry, I like to remove most of the material and then make a final clean up cut. I sometimes remove some of the material with the BT3100 and then clean up the cut on the router table.

Jim

[crokett]

From my own experience, taking passes that are somewhere between 1/8 and 1/4" deep works best for my 1/2 spiral cut bit with 1/2" shank. It is the best compromise between speed and a good cut. Anything over 1/4" deep and I get a ragged cut.

[poolhound]

use the turret

I just set my final depth with the stop, and then use the turret thingy (can never remember what its called) to make multiple passes intil it down to final depth.

Jon

[jonathanb3478]

From my own experience, taking passes that are somewhere between 1/8 and 1/4" deep works best for my 1/2 spiral cut bit with 1/2" shank. It is the best compromise between speed and a good cut. Anything over 1/4" deep and I get a ragged cut.

What router do you use? Thanks!

[softop41]

router bit cut depth

The advice I was given and follow is this: The max depth should never be more than 1/2 of bit diameter for 1/2" shank bits over 1/4"; 1/4" and under, regardless of shank size, should be 1/4 of bit diameter max. I can't remember where or who this came from but it has been working for me now for several years. Granted, this most directly applies to dado cutting.
Just my 2c worth
Jerry