routers can be scary tools if you don't know what you're doing and generally speaking the larger the router bit the more dangerous it can be i have a lot of router bits in my wall rack and some of them are pretty big but this is the one that tightens my pucker the most every time i use it it's three and a half inches in diameter and it weighs nearly three quarters of a pound this would hurt if i dropped it on my foot it's designed to cut the profile around the edges of a raised panel we most recently used it to create giant cherry panels for a chest of drawers and i thought it would be a good opportunity to show you what a hunk of steel like this looks like in action and to talk to you about the special precautions you have to take with these larger router bits because your bit doesn't have to be as big as a ship's propeller to give you problems if you don't follow some guidelines and my view on this is a little bit different from what everyone else seems to say first of all a bit like this should not be used in a handheld router even if your router is powerful enough the weight of the bit will make it harder to control and the consequences of losing control are far too high this is a router table only bit and i think other extra large bits should also be used for the router table only the problem is where do you draw the line if you look at my bitrac and by the way we do have a video about this rack which i'll link to below so you can see its unique design and maybe even grab a set of plans to make one for yourself most of these straight bits on the bottom and the various edge profiles are perfectly safe in a handheld router these are table edge profile bits and they get a little larger they're about two and a half inches in diameter now normally people say that that is pretty much the maximum bit size you should use in a handheld router and i tend to agree anything over two and a half inches is safest used in the router table but that doesn't mean everything two and a half inches and smaller are safe with a handheld router these large profile bits are relatively light for their size they weigh just under four ounces on the other hand this two inch straight bit weighs more than twice as much it's nine ounces now even though this straight bit is smaller in diameter than the table edge bit and it is well within the range that's considered safe for a handheld router i still consider it sketchy at best handheld because it just has so much mass and that's something that i rarely hear people discuss heavy bits like this one or the large box cores and the round overs and the big bull nose bits these can present their own issues because all that extra weight can combine with any runout in your router spindle and cause micro vibrations you may not notice it you may even get a decent cut but those vibrations can cause the bit to come loose in the collet it's happened to me thankfully i had it in a router table so gravity just caused the bit to drop deeper down inside the collet but if i've been using it in a handheld router which is run upside down gravity might have dropped a bit out of the collet and potentially made it into a projectile in fact while i generally tell people not to over tighten the router bits i do apply some extra torque when i'm using a large or heavy bit because of the potential for micro vibrations if there is any run out in the router spindle some bits have both mass and diameter our three wing panel cutter is an example of that or this huge lock miter bit what a big chunk of steel this thing is not only would i want to run this in a router table with a good tight collet but i'd also turn the router's speed down significantly the larger the bits diameter the slower you should be running it take these two examples one is three and a half inches in diameter the other is an inch and a half in diameter but what really matters is the circumference because that's the path the cutters on the rim must take to complete a single revolution and there's a big difference between these two bits the larger bits cutters must travel around 11 inches per revolution while the smaller bits cutters only travel about 4 inches per revolution so let's say that these two bits are run at the same 22 000 rpm the smaller bits cutters on the outside rim will be moving at about 125 miles per hour but the larger bits cutters having to travel nearly three times the distance per revolution will be traveling near a blistering 230 miles per hour same router settings but more than 100 miles per hour faster router bits are not designed to move that fast or to endure that much centrifugal force it'll generate too much heat and depending on the quality of the bit it could cause a cutter to come off or a bit to come loose but if i slow the router down to about 12 000 rpm the cutters on this big bit will now be traveling at that much safer 125 mile per hour-ish range so we have two different bits traveling at vastly different rpm but cutting at roughly the same speed it's an interesting concept that some people have trouble wrapping their heads around so here's a simple chart from an old magazine that you can use as a guide now what if your router has numbers on the dial and not specific rpm settings how do you know where you're setting it well the first thing i do is look in your manual or search online to find out the range of speed that your router is capable of this router ranges from about 9000 on the low end to about 22 000 rpm on the high end so i know that dial position 1 is 9000 and dial position 5 is 22 000 and now i can do the math to figure out the settings in between and record them somewhere for future reference most variable speed routers especially full size range from the 8 9 000 on the low to 22 to 24 000 on the high so if you can't find something specific to your router you might use those numbers as a general range but do some testing with various bits slowly increasing their speed if you feel any vibration at all back it off and then record the max speed for that bit somewhere handy so you can use it next time another consideration when using large bits is the aggressiveness of the cut if you have a powerful router motor you may be able to take a relatively deep cut particularly at the router table this one is more than three horsepower and you can see it handles this cherry pretty well even so i usually don't like to take a full cut with a very large bit for one thing if it catches on something like a knot an aggressive cut could rip a smaller piece of wood from your hands that's why paddles are an absolute must with one of these large bits but the quality of the cut is also a concern even if it could be cut in a single pass you're working the router and your bit much harder than you need to you could get chatter marks you could get scorching definitely you'll get more tear out if the wood grain isn't perfect you'll simply get a much smoother cleaner surface if you cut a
