# cutter diameter vs cut depth



## The Warthog (Nov 29, 2010)

Is there a rule of thumb for how deep a cut you can make in a single pass with a particular router and bit? I tried to cut a ¼" slot in ½" oak today, and messed it up as the piece took on a life of its own and cut a kidney shaped slot instead of a straight one. I had the piece held against a fence. I would have thought a 1/8 sq. in. channel would not be too much for an 11 amp router. I have successfully cut fairly deep and wide grooves in pine before I was told I couldn't. 

Any advice?


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## bobj3 (Jan 17, 2006)

Hi 

The rule For me, if the bit is 1/2" I can cut a slot 1/2" deep and the same thing is true for a 1/4" bit. 1/4" deep no big deal, but this is where the feather boards come into play to keep the stock to the fence..but the bit must be sharp,but I now use the ski jig for that type of job 

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The Warthog said:


> Is there a rule of thumb for how deep a cut you can make in a single pass with a particular router and bit? I tried to cut a ¼" slot in ½" oak today, and messed it up as the piece took on a life of its own and cut a kidney shaped slot instead of a straight one. I had the piece held against a fence. I would have thought a 1/8 sq. in. channel would not be too much for an 11 amp router. I have successfully cut fairly deep and wide grooves in pine before I was told I couldn't.
> 
> Any advice?


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## Mike (Nov 22, 2004)

Roger, did you place your wood against the fence and push it from right to left?


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## wbh1963 (Oct 11, 2011)

In my limited experience this is relative to species and to some degree grain and knot patterns. In my 'experiments I have waded in slowly, increasing the depth of cut for a specific type of wood/diameter combination paying attention to how well it was going as I did. Clear and straight softwood is always easier to work, including 'hog cutting' of any sort, than pig wood (you know, the knotty & interlocking timber from hell stuff!) or hardwoods.

I think moisture levels come into play also in the case of wood that has never been dried to the point of equilibrium. 

Any 'aspect' that makes the cutting 'tougher' decreases the real world maximum depth of cut in a given scenario.

It surprised me a little to read that Jigs uses ski jigs to cut slots. It also made me smile on account of feeling like I learned something!

I had to slow down an think about it for a while to come up with my best guess on why he does it that way (instead of the way I would have guessed he did). Hopefully he will jump right in and set me straight if my 'guess' is off base...!

With the workpiece clamped down and the weight of a router in skis the 'flow' of the cut is controlled a lot easier. The router weighs more than the average workpiece and the skis are most likely being guided in their path along an appropriate straight edge. I think its a physics thing, but that is also a guess.

The other think I think I learned here is my idea about baseline maximum depths was off base. I would have assumed I could get away with more depth with the lower diameter bit instead of the other way around. Thinking about what depths I have actually ended up using after I wade in, I can see how it isn't and am guessing that is a chip ejection path thing. 1 to 1 ratio seems like a great baseline, well at least up to 1/2". Not saying I would try to take out a 1" deep trench in a single pass just because the bit was 1".


Thanks to Roger for asking and Jigs for speaking up!


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## bobj3 (Jan 17, 2006)

Hi

The router table is Not the safe way to put a slot in place Harry got me on the right track with the ski jig..it makes the job so easy and safe..and you are right about the mass of the router doing the work for you, it can be a small router or a tank router I have posted many pictures how to do it the safe way in my uploads.


Just for a side note,,I put in 1" wide slots and 3/4" deep in place in one pass with a plunge bit in place, with the right bit it's easy.

===


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## Drew Eckhardt (Aug 2, 2008)

The Warthog said:


> Is there a rule of thumb for how deep a cut you can make in a single pass with a particular router and bit? I tried to cut a ¼" slot in ½" oak today, and messed it up as the piece took on a life of its own and cut a kidney shaped slot instead of a straight one. I had the piece held against a fence. I would have thought a 1/8 sq. in. channel would not be too much for an 11 amp router. I have successfully cut fairly deep and wide grooves in pine before I was told I couldn't.
> 
> Any advice?


The lesser of 1/2 bit diameter and 9/64" square (per Pat Warner, like 3/8 x 3/8, or 1/2 x 9/32).


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## wbh1963 (Oct 11, 2011)

Hats off (again!) to Mark for founding this forum! Hats off to Jigs, Harry, JW, Skies, Bernie, BigJim & all the rest as well for their contributions to this 'crafter's haven' known as The Router Forums. This thread is one of a zillion examples of 'collaboration in action'!

I have only done a few slots on a table. I didn't care for the dynamics of removing the bit guard and having to 'nose down' the workpiece on top of a spinning bit. Yeah, it isn't that hard to do, and is possibly the way some people will always choose to do it, I'm just not one of those that wanna do it that way.

I have had great luck plunging down overhead routing style. After I decided I didn't care to do slots on a table, I gave up 60 bucks or so for a cross slide vise. (HF 99.00 model regular on sale with a 20% off coupon!). Adding the vise to the equation exceeded my expectations so much that building out a 'real overhead routing rig' is a higher priority than crafting up a fancy table, on account of having enough 'so so tables' to get me by.

Largely due to simplicity, and this thread, a set of skis (or three) seem appropriate before an overhead rig. It doesn't take much of a rocket scientist to figure out that
building the skis is good practice for the overhead rig, horizontal rig and table that will someday follow them. Then of course there is the fact that the ski's will probably be the best way to craft up some of the parts needed for all three projects.


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## The Warthog (Nov 29, 2010)

Thanks guys! I finished the job today by drilling four connecting holes on the drill press with a ¼" drill bit, and chopping out the waste with a ½" chisel and a second cut file. Looks very nice.

Mike, I think I started out going from left to right, but then tried to make it a little longer on the left side. It happened so quick I was left wondering what it was.

When I had to cut some dadoes in a band saw table the day before, I did it 1/8" at a time, and ended up with a nice smooth job. That was in plywood, and come to think of it is the first time I've routered plywood.

Thanks again.


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## grbrico (Feb 16, 2012)

bobj3 said:


> Hi
> 
> The router table is Not the safe way to put a slot in place Harry got me on the right track with the ski jig..it makes the job so easy and safe..and you are right about the mass of the router doing the work for you, it can be a small router or a tank router I have posted many pictures how to do it the safe way in my uploads.
> 
> ...


Bob,
How does one line up the cut and keep it straight using the skis? I thought the skis were just for planing.

Greg


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## bobj3 (Jan 17, 2006)

Hi Greg

They can be used in many ways, below is just one of them.



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grbrico said:


> Bob,
> How does one line up the cut and keep it straight using the skis? I thought the skis were just for planing.
> 
> Greg


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## grbrico (Feb 16, 2012)

Bob,
Thank you. I see now how to set it up.


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## bobj3 (Jan 17, 2006)

You're Welcome Greg

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grbrico said:


> Bob,
> Thank you. I see now how to set it up.


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