# setting router bit depth question



## sirwoodington (Jan 24, 2012)

Hi,

Newbie with a routing question that I'm sure has an obvious answer I am simply not seeing.
Say I have a piece of stock and I route to depth A. Later, after having changed the depth on my bit on the router to route something else I come back to that piece of stock and want to route a different part of the stock to depth A. I need the two parts of the stock to both be at exactly the same depth (A).

My thinking was to set the router on top of the 'original A' and adjust the depth until, as best as I could tell, the router was sitting flat on the workpiece. The result, however, as you can hopefully see from this pic is that it took out a little too much material as you can see from the differences in the two depths. 










In the future, how do I make sure that the two depths line up exactly?

If it matters, I am using a Dewalt 618 with the d handle attachment since I find it easier to control.

Thank you in advance.

Nathan


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## Gene Howe (Feb 28, 2009)

BTDT! 
I'll often use a 6" Stanley adjustable square to set the bit height. If you leave the square set, you can always go back to that height.
I also have a bunch of shims, i.e. laminate samples, playing cards, pieces of pop/beer cans..etc and several pieces of keyway stock of various sizes. 
Between all that stuff, I can find just about any height or depth I need. In your case, I'd have set the bit using some combo and then used it to reset. 
Numbers confuse me. I try never to use a tape or rule, if I can avoid it.


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## Dave Paine (May 30, 2012)

I understand the challenge. You may not always be able to achieve exactly the same depth if you are not able to finish the routing in one step.

I think many of us have experienced this at one time.

Things to consider to attempt to minimize or eliminate the issue.
a) Cut a piece of scrap to the depth of the cut. With the router unplugged, place the router on its head. Place the scrap on the base. Adjust the height until the bit is flush with the scrap. The method which works for me is to have another piece of scrap placed over the bit and depth piece, and lower the bit until the extra piece of scrap touches the depth piece.
This method eliminate the pressure of the router slightly pushing the bit into your earlier cut out area.
b) Cut a piece of scrap to e.g., exactly 1/4in. Again place router on its head and the piece of scrap over the base near the bit. Measure the height of the bit with a dial caliper. Adjust height until the dial caliper measurement + scrap thickness = desired depth.

I feel measuring the depth off the wood to be cut will give you the best chance of being able to repeat the depth setting.


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## Crusader (Jan 14, 2013)

I'm not familiar with that model of router, but does it have a fine depth adjustment? 
What you are doing (to me) is on the right track, when you lower the bit down to the previous cut I think it's the weight of the router body pushing the bit down. Maybe try and compensate by using a piece of card stock or something similar to hold your bit up say a 64th.
Also wouldn't hurt to have a sacrificial piece that you can test on.


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## sirwoodington (Jan 24, 2012)

Thanks everyone. Gene: your method strikes me as really smart--to set an adjustable square so I can return to that bit depth.

For the other folks that asked whether my router has a fine tune adjustment--it does but aren't I just kinda guessing there? If I pull it back too far dont I then have the opposite problem where I cut shallower than A? (Same sort of question for those that suggested testing on a scrap piece--how would I know if the two line up?)

Sorry if I am being dense.

Thanks.


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## :-) (Jan 18, 2013)

sirwoodington said:


> Thanks everyone. Gene: your method strikes me as really smart--to set an adjustable square so I can return to that bit depth.
> 
> For the other folks that asked whether my router has a fine tune adjustment--it does but aren't I just kinda guessing there? If I pull it back too far dont I then have the opposite problem where I cut shallower than A? (Same sort of question for those that suggested testing on a scrap piece--how would I know if the two line up?)
> 
> ...


I'm a total novice but have done enough router work to hopefully shed some light. The fine tuning adjustment works best for me because when locking the router, there is some creep from the weight of the router. Therefore, using the square method explained above, I would use the fine tune adjustment to get to my appropriate depth. If I have to return to another piece and recreate what I did prior, this has worked for me. The fine tuning seems almost crucial, at least for me.


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## ctwiggs1 (Mar 30, 2011)

I'm lazy -I always have some scrap 2x4s laying around that I just use as test pieces.


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## bladeburner (Jun 8, 2013)

What usually happens is, like already stated, the pointed end of the bit sinks slightly into the wood. Try bringing the bit to the level desired while moving the router. At some point, the bit will drag. Now back off ever so slightly and you should be good to go. Why this works better than careful measuring is: wood MOVES! :laughing:
Anyway, works for me...Good luck.


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## sirwoodington (Jan 24, 2012)

ahhhh, ok, thanks, I will try this.


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## dt1050 (Jun 21, 2013)

a lot of the time when making a specific piece, I will write the measurements i have for the router,table saw, etc. in a tablet, then when I want to reset the router for instance I have the measurements. I also use a pencil and mark the table were a specific piece was so I know were to put it next time, this also helps when cutting/routing a bunch of pieces, I can keep an eye on the pencil mark to make sure the fence hasn't moved. (a piece of tape on the fence and a striaght edge works for the depth). so in your instance, part A. I'd check my measurements in the tablet, find the mark on the tape and it's all set, run a piece of scrap wood to check it to be sure it's were it should be. once the project is complete I take the tape off, wipe the equipment down to remove the pencil marks and start the next project. keep your measurements in case you need to make another one.


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## del schisler (Nov 5, 2009)

sirwoodington said:


> ahhhh, ok, thanks, I will try this.


look's like you are using the router from the top? and not in a table ? from the top it is very hard to get it exact but you should be able to get it closer , just looking at the 2 pictures, if that is the only 2 that you are going to make, if the last one is deeper , and you want the other one to look a like , just recut the other one , and you have 2 that look alike, other than that a close measrument of the bit to work has to be measured better, i use a table mounted routing, have 5 tables and have been routing for yrs, i guess when you do the first routing have a scrap piece the same size and route it now that will be the set up for the next time, i have lot's of templete's , just mark the name on them , if you are like me you can forget ? also look's like the piece didn't have a smooth edge for the beiring to ride on, this will transfer all demples in the wood to the cut also . good luck their are set up bar's also for this which are very good for bit height of course they are in even steep's tho like 1/4 3/8 1/2 ect they are square and set on the base of router than rase the bit up , you get the idea


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## cabinetman (Jul 5, 2007)

I usually make a sample depth pass on a scrap to make sure it's correct. So, If I change the setting, or bit, I make another sample of that one. If I have to go back to the first one, I have a sample to use to check the setting.

If you have a bunch of routers, just leave the setup. Unfortunately many aren't stocked up with extra routers in order to do that.


















.


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## Hammer1 (Aug 1, 2010)

Looking at your pic, it shows burning and an uneven cut on the edges, in addition to the depth difference. You are probably cutting too deep in a single pass and you aren't using some type of guide to keep things straight. There are many ways to guide a router so you aren't free handing, these will give you more control and a more precise outcome. Plan your work and processes so you do all the like work at the same time and same settings. It's much easier and more efficient than trying to go back and re-set things to match a previous cut. This applies to everything you set any tool up for. With a guide and doing all cuts at the same time, you could have made the depth cut incrementally, eliminated burning, got a more uniform cut and wouldn't have to worry about matching something done previously. Little things like organization and doing like procedures at the same time separate the pros from the beginners, I know, I've been both.

Routers have a ring that you can use to set depth with. First you set the base so the router bit is flush with the base. Use a straight edge to feel across the base so the bit is flush and lock the depth. Set the ring to 0, unlock the depth lock and turn the base to the desired measurement on the ring, without moving the ring. This is extremely accurate and repeatable, even if you change the bit. Actually measuring the bit projection can be a bit iffy, especially with profile bits, the ring is dead on as long as you accurately line up the marks. 

Routing larger openings that the base doesn't completely cover can cause the router to tip. There are times when you want to make a larger base plate so you have a wide surface to bear on. When cutting larger openings, start in the center and work your way out. If you do the perimeter first and waste is left in the center, a chunk can get loose and jam between the bit and the routed opening, it can kick the router out of control and then you'll cut a wahoo that you don't want.

Cutting openings like the one you pictured are nicely done by using a template along with a template guide on the router. You'll be able to repeat that same opening precisely as many times as you want. It takes an extra step or two but it takes your work to the next level.


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## woodnthings (Jan 24, 2009)

*more advice*

What ever means you use to establish the depth of cut...measuring tool like a tri-square, or sample piece, make certain the bit is securely locked in the collet as vibration may change the length the bit extends from the collet. A small "O" ring dropped into the collet will act as a stop for the bottom of the bit when setting up.

Here's some depth gauges:
Wixey WR25 Mini Digital Height Gauge - Amazon.com


Amazon.com: Empire Saw And Router Gauge Set (10304): Home Improvement


Amazon.com: Trend GAUGE/1 Depth Gauge: Home Improvement




Also make certain there is enough perimeter around the opening to support the router's base for the entire process. It may be good to add more scrap of the same thickness around the opening to support the base. Do not tip the router while making the cut as that will change the depth of cut.


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## cabinetman (Jul 5, 2007)

woodnthings said:


> Here's some depth gauges:
> Amazon.com: router depth gauge


That link doesn't work.








 







.


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## durdyolman (Mar 22, 2013)

I have a theory about what gave you the results you got. Most, if not all, power tools have a certain amount of "thrust", meaning the motor/driveshaft assembly moves in and out ever so slightly. Even with the best of thrust bearings this happens. When you placed the bit onto the existing cut and lowered the router to the work piece, the weight of the router pushed the shaft to the innermost position of the thrust. When you started routing, the weight of the motor/driveshaft pushed the assembly to the outermost position of thrust. Hence the deeper cut. I am a firm believer in the procedure most have mentioned, using a good tri square to set your initial depth, set the square aside unchanged, and use the same square for the next time you set your depth. If not that, as has been mentioned also, using the procedure you did, raise the bit slightly, try it, and lower it as needed.


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## woodnthings (Jan 24, 2009)

*hmmmm*

It works when click on it in your quote ...? :blink:


That link doesn't work.....?


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## TimPa (Jan 27, 2010)

the best idea was to have made a test piece that you can come back to. we don't always think we'll need one though. measuring bit or blade height is not accurate enough for a guarantee. this falls under the category of _"sneak up on it_". iow. start shallow and progress the bit depth until you reach it. works every time, unless you get inpatient and take too big of a step.


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