How are router depth adjustments supposed to work?

[Stephen Tashiro]

I have a least three routers and the story with the depth adjustment is roughly the same on all of them. There are one or two collars that are threaded around the body of the router and apparently you are supposed to turn them to adjust the depth. There is also some sort of lock or clamp that holds the depth one you set it.

I don't understand why these mechanisms are supposed to be practical. Until the lock is set the bit slides up and down relative to the base and this is heavily influenced by gravity. So it my router was standing straight up with the base supported on something, these collars might make sense. However most of the time when I adjust the depth of cut, I have the router held sideways and am using a square or something else to measure the depth. So the collars are just a nuisance. I simply maneuver the the bit to the right depth and lock it there.

The only reasonable way to use the collars (which I have imagined but not tried) would be like this. You keep a sample of wood with a cut at some know depth. For example for your 1/2 inch rabbiting bit, you have some stock where the depth was set at 1/2 inches. You stand your router up on this stock and let the bit fall to that depth. You adjust the collars so they hold the bit there. Then you use the scale on the collar to go plus or minus the amount that is needed to make the depth of cut that you want.

Do people do things like that? I find the scales on the collars hard to read, especially when there are two collars to worry about . All those scraps of wood to keep track of - one for every bit.

[Tom Veatch]

My handheld routers are flat on the top, so I just turn them upside down, set them on the table, release the lock (the bit is already positioned and tight inside the collet) and use the height adjustment (the rotating collar?) to move the motor up or down in the base until the bit extension relative to the baseplate is where I want it, reapply the lock and make a test cut.

I'm not entirely sure I follow your description since it sounds like you're trying to make height adjustments by varying the position of the bit inside the collet. The bit should be fully inserted but not bottomed out in the collet.

If you post the model numbers of your routers, advice more specific to your particular routers can be given.

[Greg Hines, MD]

I have a least three routers and the story with the depth adjustment is roughly the same on all of them. There are one or two collars that are threaded around the body of the router and apparently you are supposed to turn them to adjust the depth. There is also some sort of lock or clamp that holds the depth one you set it.

I don't understand why these mechanisms are supposed to be practical. Until the lock is set the bit slides up and down relative to the base and this is heavily influenced by gravity. So it my router was standing straight up with the base supported on something, these collars might make sense. However most of the time when I adjust the depth of cut, I have the router held sideways and am using a square or something else to measure the depth. So the collars are just a nuisance. I simply maneuver the the bit to the right depth and lock it there.

The only reasonable way to use the collars (which I have imagined but not tried) would be like this. You keep a sample of wood with a cut at some know depth. For example for your 1/2 inch rabbiting bit, you have some stock where the depth was set at 1/2 inches. You stand your router up on this stock and let the bit fall to that depth. You adjust the collars so they hold the bit there. Then you use the scale on the collar to go plus or minus the amount that is needed to make the depth of cut that you want.

Do people do things like that? I find the scales on the collars hard to read, especially when there are two collars to worry about . All those scraps of wood to keep track of - one for every bit.

The purpose of those collars are to allow you to increase or decrease the depth by small fractions of an inch. If you, say, set your depth of cut to 1/2", but then decide that you need it just a bit deeper, say, 1/128", the collar will let you do that. Rotate it to the zero point by the mark on the router body, unlock the body, rotate it until you have advanced it by the 1/128" (or whatever) and clamp it down again.

Doc

[Peter Froh]

Here are the instructions as laid out for the PC 690:

ADJUSTING THE DEPTH OF CUT
1. Open the clamp (A) Fig. 3.
2. Hold the base (E) and turn the power unit (F) Fig. 3 counter-clockwise until the tip of the bit is above the
bottom of the base.
3. Set the tool on a flat surface.
4. Turn the power unit (F) Fig. 3 clockwise until the bit touches the work.
5. Close the clamp (A) Fig. 3.
6. Rotate the depth adjusting ring (B) Fig. 3 until the zero-line (C) is opposite the index line (D) on the
housing.
7. Open the clamp (A) Fig. 3.
8. Tip the router so that the bit is clear of the work surface. Turn the power unit (F) Fig. 3 clockwise until
the index line (D) on the motor housing reaches the desired depth indicated on the ring.
9. Close the clamp (A) Fig. 3.

PC690.jpg

I hope this helps.

[pat warner]

A serious problem to be sure. All fixed base tools have guess-work depth adjustment mechanisms. Rack & pinion, ring-hung motors, double internal spiral twisting motors, all guesses, all with lash, most with lousy fractions, many unreadable, many vague.
Try the plunger for best depth of cut target. Can often hit target depth on first try; it is possible.

[Stephen Tashiro]

I'm not trying to adjust the depth of cut by moving the bit in the collet. It's the whole "column" of the router that I slide relative to the base. The shaft, the motor, all that stuff moves.

I see that Peter's directions are an improvement on my theory. I think they amount to something like this: Unlock the depth adjustment. Position the bit so the depth of cut is zero on the work. Turn the collar (or knob or whatever adjustment you have) so it holds the bit at this depth. Note where the zero mark. Then turn the collar an additional amount until it reads the desired depth. Then lock the router. (That avoids having a jig for every bit.)

My newer Craftsman router behaves like Tom's. On my older ones, if the router is upside down and the depth mechanism is unlocked, the bit drops down relative to the base to the max depth and turning the the collar doesn't lift it. (Of course, I made the wise decision to put one of the old routers in my router table).

I've never owned or used a plunge router. Why is easier to set the depth of cut on them? The way that I imagine them, they would be harder to use than non-plunge routers when you wanted an even depth of cut.

[pat warner]

Not a problem to hit target with the plunger. But first throw out the turret, scrap it.
Lightly plunge cutter to substrate; that is the zero point. Use gages or whatever to adjust the plunge depth. Can be to the nearest .001" once you learn the signature of your router.

[Joe Scharle]

Plunge routers have a stop rod and a turret of some kind allowing you to set depth(s) past the zeroing position. As you plunge the router, the stop rod is stopped at a depth you have previously chosen. For critical depths, I remove the turret and set the plunge depth with brass setup bars. If you get one in your hands it will be intuitive.

Pat got your answer while I was trying to type.

[Cliff Rohrabacher]

I'm not trying to adjust the depth of cut by moving the bit in the collet. It's the whole "column" of the router that I slide relative to the base.

On a conventional router you don't adjust the depth while the router is under power. You make the adjustments and lock it down and then turn the power on.

A plunge router has posts and bearings to guide it during powered plunging.

[Jim Rimmer]

I have one of these and find it helpful for the initial set up.

[David DeCristoforo]

Aha! There is a difference between how "these things" are supposed to work and how they actually work. For the most part, it's "set and test" until you get it right. Some routers have better adjustments and stops than others but almost all leave something to be desired. I have found that the Bosch routers are the best in "their class", at least in this respect. Of course, you can spend some dough on gauges and setting devices which may or may not solve the problem but you still have to test your cuts before committing good stock.

[Peter Quinn]

Wait, you are saying those depth gauges are supposed to do something? News to me. I find them mostly to be a nuisance best avoided.

[Steven J Corpstein]

Not a problem to hit target with the plunger. But first throw out the turret, scrap it.
Lightly plunge cutter to substrate; that is the zero point. Use gages or whatever to adjust the plunge depth. Can be to the nearest .001" once you learn the signature of your router.

I've been using Pat's method of depth adjustment ever since I first went to his web site. This guy knows his @#$t, no 2 ways about it, take a look at some of his work.

[glenn bradley]

My routers are also flat on top. Set the depth, lock the body, route.

[Stephen Edwards]

All I know is that I don't like the kind of routers that rotate on the motor housing to set the depth of cut. I'm not sure what the proper terminology is for that style. They're awkward and annoying to use, IMHO. If the router has the additional nuisances of having the switch on the top and/or the cord exiting the motor on the top so that you can't lay the router upside down (because it ain't flat on the top), it's even more of a hassle. Those two or three design flaws aren't practical at all to me.

The Bosch routers that I have don't have those design flaws. I have another router that does have the "screw/twist" height adjustment. It's a fine little router except for that one "feature".

While I'm on this rant about design flaws, I wish that I could find a good router for hand held use that has the old trigger switch built into one of the handles. I suppose those are history because it costs more to have that type of switch. Perhaps it's because of safety concerns. I don't know. They sure were convenient to use.

I sympathize with your frustration.