routing a dado...how deep on one pass?

M

Mac

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Hi all,

Have been routing dados for the first time with my 1010, and was wondering how deep is recommended to take it in one pass?  I really want a dado of about 9 or 10mm.  Can I do that in one go without straining anything (aside from my groin when I dropped the router and attached edge guide from my workbench and lunged to catch it. I missed, but no apparent damage. Except to my groin  [crying] )

Thanks,
Rick
 
That depends on:

a) What size of router bit you're using, and

b) what material you're using it in

For example, if it's in MDF with a 1/2" bit or bigger, then 9 or 10mm in one pass is easy. But, if it's a 4mm router bit in solid oak, then you'd be better with 2 or 3 passes.

I'm not sure, but I think the general rule-of-thumb is to never rout deeper than the diameter of the bit.
 
Much depends on the type of wood, but I would do that  in 2-3 passes. What's the rush?

Bob
 
I should have been more specific. MDF, 13mm bit (about half an inch).

Bob...what's the rush indeed. Nicely said.

Rick
 
Mac:

What Bob says is pretty good advice, especially if you enjoy the process as much as the results. And even if you are trying to get results faster, you can generally get a cleaner cut in multiple passes.

I'm not sure you were asking a complete question, however. Even if you were taking multiple passes, you can come out with a less than optimal result. The feed and speed are as important as multiple passes.

Generally speaking, with a handheld router performing a certain task, you will be able to move the router along the workpiece comfortably at a given feed rate. Different routing tasks will cause your feed rate to very a bit. You should never be moving the router so fast that the bit starts to chatter. If it does, the danger level increases rapidly and the results suffer.

So, with your feed rate a constant, you have to figure out the optimal spindle speed. Sometimes people just crank it up. Though this may work on some species, it won't work on others. Maple, for instance, burns easily and then it's a hassle to clean up if you can within the configuration desired. The burning is caused by the cutter spinning next to the work piece and not really cutting, just spinning and causing heat buildup from friction. Not only is this scarring/marring the work piece, but it is also heating up the cutter and potentially causing premature dulling.

To find an optimal spindle speed, take a practice piece (of the same species and preferably, the same piece) and perform the same kind of cut you are planning for the real work piece. Dial down the spindle speed until it starts to chatter at your normal feed rate. Then increase it slightly until just past where the chattering stops but don't overdo it. You want to be just faster than where it wants to chatter. At this spindle speed for your feed rate, you will get the cleanest cuts and not over heat the bit or the work piece. If your bit is real hot after a cut, you are probably not optimized.

Now you're ready to take on the real work piece. With some practice, you'll get to know the different speeds for various work piece types within an acceptable range and will find that you get real close on your first try.

Anyone who has ever milled plastic will know this in spades. Spinning the bit too fast in plastic will remelt the shavings in a dado and you might have to rout them out again.

Tom
 
Tom,

I really appreciate you taking the time to go into so much useful detail.  One further question though if I may, and sorry that it'll be so obvious to you: how will I know when it starts to 'chatter'? Does this mean it'll start to jump around a bit?

Thanks again.
Rick
 
You'll feel it and you'll see it in the cut. When it's cutting normally it's like butter.

Tom
 
Once you get a bit more experienced you will know by the sound it makes, but if in doubt, slow down.

Woodguy.
 
I've found my 1400 goes through MDF really smooth. I don't recommend racing through the cut but the Festool routers seem to handle a continuous output more reliably than my other non-Festool router. I look at my 1400 cuts and I think to myself, nicely done, Festool, nicely done. The soft start is a pleasure and stops the sudden "jump to attention, ready for action, sir" I get in my other router. The two second shutdown is a joy as well. I sometimes toasted cuts getting the router clear of the work but that sudden and smooth shutdown makes it more controllable. I'm sure there is a limit to how deep logic tells you to cut in one pass but Festool's router encourages you to probe a bit deeper than you'd think of doing with another. I'm note sure if that's a good thing or not.
 
Peter HS said:
I'm sure there is a limit to how deep logic tells you to cut in one pass but Festool's router encourages you to probe a bit deeper than you'd think of doing with another. I'm note sure if that's a good thing or not.
Click to expand...

Router bit manufacturers aren't crazy I think. So you should be able to use the bit for the full length of the cutting edge, nothing wrong with that.
 
Alex said:
Peter HS said:
I'm sure there is a limit to how deep logic tells you to cut in one pass but Festool's router encourages you to probe a bit deeper than you'd think of doing with another. I'm note sure if that's a good thing or not.
Click to expand...

Router bit manufacturers aren't crazy I think. So you should be able to use the bit for the full length of the cutting edge, nothing wrong with that.
Click to expand...

Of course, but not necessarily in one pass.
 
Really you shouldnt need to go quiet that deep anyway I normally do 5 or 6 mm deep housings as we call dados here in England and they are fine.
 
Hi Rick,

I am a bit late but will chime in here.  I do a lot of 10mm deep grooving while cutting female sliding dovetail slots in solid hard woods without incident.  I have done it with various size DT bits from 12mm to over 20mm and with most all of the Festool routers.  The 700 works just as well as the 2200 for this purpose.  I only use Festool router bits and I have never broken one of their DT bits nor have I ever needed to sharpen one.  I would expect dados would be the same.  As a general rule make the one pass depth no greater than half the cutting diameter of the bit.  That will serve you well until you gain more direct experience and know when and if you can exceed that for the work you are doing and the feed rate you maintain.  Hope this helps.

Jerry

Mac said:
Hi all,

Have been routing dados for the first time with my 1010, and was wondering how deep is recommended to take it in one pass?  I really want a dado of about 9 or 10mm.  Can I do that in one go without straining anything (aside from my groin when I dropped the router and attached edge guide from my workbench and lunged to catch it. I missed, but no apparent damage. Except to my groin  [crying] )

Thanks,
Rick
Click to expand...
 
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