# 1/4 inch dado



## jeffreysmith300 (Apr 14, 2013)

on a few different projects I've needed a 1/4'' dado - 1/4'' deep. I've used my router table to do this but inevitably the 1/4 straight cutting bit gets too hot (i'm assuming) and breaks. I've also tried an up-cutting bit - same broken bit. I tried a 1/4 slot-cutting bit but that also gets extremely hot. in both cases the router was set to ~4,000 rpm

I could always go back to using a dado blade but it makes stop dadoes pretty clunky. 

can anyone suggest an easier way to make a stop dado with a router table?

thanks in advance!


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## MT Stringer (Jul 21, 2009)

Are you cutting the dado in a single pass? I usually make several passes on the router table. I haven't broken any bits (including the 1/4 inch and the 3/32 inch for plywood drawer bottoms).

Freud and Whiteside make up most of my bits, along with a few from MLCS.


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## jeffreysmith300 (Apr 14, 2013)

yes, single pass. sounds like i need to break it down to 3 or 4 ?


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## Woodenhorse (May 24, 2011)

It could be one of several factors: feed rate (too fast), dull bit, too aggressive a cut in dense wood or any combination of these.


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## MT Stringer (Jul 21, 2009)

jeffreysmith300 said:


> yes, single pass. sounds like i need to break it down to 3 or 4 ?


I think so. A good sharp bit is nice to work with. I built 22 drawers for our kitchen (hard maple and poplar), and fourteen for my sister in law's rent house (poplar), and 18 more on other projects (maple and poplar) and never had any trouble.

Good luck.
Mike


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## GeorgeC (Jul 30, 2008)

MT Stringer said:


> Are you cutting the dado in a single pass? I usually make several passes on the router table. I haven't broken any bits (including the 1/4 inch and the 3/32 inch for plywood drawer bottoms).
> 
> Freud and Whiteside make up most of my bits, along with a few from MLCS.


He is only doing 1/4" deep. Should be absolutely no problem.

I would guess poor quality bits.

George


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## ryan50hrl (Jun 30, 2012)

Ya this seems odd...1/4 wide by 1/4 deep should be pretty easy for a good bit. The speed should be much higher than 4000 rpm...what kind of wood are you cutting?


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## hwebb99 (Nov 27, 2012)

I would try running the router faster. Like 20,000 rpm.


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## Steve Neul (Sep 2, 2011)

It sounds like it's building up debris causing friction. You might try a spiral bit.


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## BigJim (Sep 2, 2008)

I am curious to know what he is cutting also, if cutting wood are you using HHS or carbide bits. 1/4 inchX 1/4 inch should be no problem at all in most woods.

If you are popping bits there is something wrong.


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## CNYWOODS (Apr 22, 2012)

Try the 1/2" shank versions.


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## ryan50hrl (Jun 30, 2012)

I made the mistake of buying a hss bit once.....never again. It burned and clogged and worked terribly. Good bits make all the difference.


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## jeffreysmith300 (Apr 14, 2013)

Thanks to everyone for the responses. I'll try to answer some questions this brought up. I've tried 2 methods for cutting these grooves in both cases I'm cutting walnut and at the same rpm (about 4,000 i believe)

1. New whiteside carbide tipped slot cutting bit - 1/2'' shank - cut burnt the wood so badly, i didn't finish the first one.

2. New 1/4'' up cutting bit - first several cuts worked very nicely but after about 6 or 7 the bit just broke off.

thanks again!


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## Woodenhorse (May 24, 2011)

If your rpm is really at 4000 then your feed rate is too fast and that's why you're snapping bits. You should be at 20,000 rpm or greater. A 1/4" router bit set for 1/4" depth should chew through walnut with no trouble at all. The bits are snapping because you are forcing the cut and applying side pressure to a bit that has nowhere to go because it can't cut the wood fast enough.


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## TimPa (Jan 27, 2010)

jeffreysmith300 said:


> Thanks to everyone for the responses. I'll try to answer some questions this brought up. I've tried 2 methods for cutting these grooves in both cases I'm cutting walnut and at the same rpm (about 4,000 i believe)
> 
> 1. New whiteside carbide tipped slot cutting bit - 1/2'' shank - cut burnt the wood so badly, i didn't finish the first one. we do this all day on small shaper at 8k rpm. 4 cutter or 3 cutter should work fine! check rotation.
> 
> ...


....


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## jeffreysmith300 (Apr 14, 2013)

i don't have a specific reason for the 4k. I don't recall why my router is set there - i'll crank it up a bit and see how that goes.


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## Trav (May 30, 2011)

jeffreysmith300 said:


> i don't have a specific reason for the 4k. I don't recall why my router is set there - i'll crank it up a bit and see how that goes.


Run it full speed. The only bits that get run any slower in my shop are larger diameter bits that probably achieve the same cutter speed at a slower rpm.


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## Tree Hugger (Sep 1, 2011)

Is there any chart showing recommended surface feet per minute for various woods ?
In machining the formula is Surface Footage X 3.82 divided by the diameter of the bit.
Feed rate in inches per minute is = Chip Load ( how much each tooth of the cutter is cutting per pass) X RPM X number of teeth of the cutter.
An example in steel .
With a recommended 250 sfpm to machine tool steel ., I would run a carbide end mill at 3820rpm(250x3.82= 3820)
Charts would tell me recommended chip load so that I could calculate feed rate.
Feed rate would not be so useful as many things are hand fed by feel( in woodworking) , but I would think surface footage could come in handy.


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## TimPa (Jan 27, 2010)

jeffreysmith300 said:


> 1. New whiteside carbide tipped slot cutting bit - 1/2'' shank - cut burnt the wood so badly, i didn't finish the first one.


i would recommend that you check the rotation direction on this cutter. slot cutters would have easily cut through hardwoods, for more than one board. maybe the cutter was assembled onto the arbor facing the wron direction, 50-50 chance.


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## jeffreysmith300 (Apr 14, 2013)

Thanks TimPa - looks like you hit the nail on head and boy am I embarrassed. The bit I'm using is a 1/2'' shank with a replaceable cutter head and in my case, I put the cutter on upside down. That certainly would explain the lousy performance! I flipped the cutter bit over - I'll give that a shot but I'm pretty sure with the blades in the right direction I'll do much better!


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## TimPa (Jan 27, 2010)

do not be embarassed, i would bet the farm that EVERYONE on this board has made a similar mistake sometime in their woodworking career. my motto is, try not to make the same mistake twice!


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## Tree Hugger (Sep 1, 2011)

Ha ! Been there done that . The results are more spectacular in the metal working trades. ( running cutters backwards).


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## Toolman50 (Mar 22, 2015)

*Breaking router bits*



GeorgeC said:


> He is only doing 1/4" deep. Should be absolutely no problem.
> 
> I would guess poor quality bits.
> 
> George


I agree, 1/4 wide and 1/4 deep can be done in one pass easily. Something's happening here. Most routers turn much faster than 4000 rpms. Maybe the speed is too slow, but that still should cause bits to break.


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## jeffreysmith300 (Apr 14, 2013)

*Thanks!*

Thanks to everyone for their suggestions!

after flipping the head over and running it in the correct direction the bit cut the 1/4'' deep dado just like a hot knife through butter. Exactly what you'd expect.


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## igster (Oct 31, 2013)

I made the same mistake after getting a table saw dado set and using it for the second or third time...I had put the blades on facing the wrong directiron, and when I went to make a dado the saw made this horrible noise and vibration in addition to not making the cut... It took me a few minutes to realize my error and then it was facepalm time, as i was in the middle of a demonstration on making a fish tank stand out of 2x4s...


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