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Router table construction problems - routing the rabbet for the plate

Saville's picture

Ok so I've wrestled with this for a couple of days and done some experimenting..and failed..so now I thought I'd avail myself of the collective wisdom of the Knots group. Here's the deal:

I got some nice 3/4" birch-faced plywood, and a Triton router,  and I want to make a router table. I bought the Bench Dog Pro-Plate router table plate to mount in the table top, and from which to hang the router. I've got a 1/2" x 1/2" router bit with a roller bearing at the top.


I want to route a ledge in the 3/4" plywood to place the mounting plate. I need to set the height of the bit so that when I put the plate on the ledge, the top of the plate is perfectly in line with the table top.


I tried it on some scrap. I set some straight edges (3/4" ply)  around the plate using carpet tape. I then set the bit height by setting the Bench Dog Pro-plate on top of the straight edge, putting the router on top of that, and "plunged" the router down until the bit touched the table top. I was concerned that the sharp bit would dig into the wood when I pushed the router down, so I did it gently.

This resulted in a rabbet that was too shallow: I routed out the ledge and cut away the waste. I set the plate on the ledge and the plate fit perfectly around the perimeter BUT it was just a smidge too high.  I could feel my fingernail catch on the plate as I ran it from the table top to the plate.  I tried to take down the ledge with sandpaper but that didn't work.

In subsequent attempts, I set the bit height by setting the router upside down, putting some 3/4" ply scraps on the base and then the router plate. I set it such that running my fingernail from the bit to the plate and in the opposite direction didn't "catch" my fingernail. I looked at the setting with a magnifying glass and it looked right. This method does not allow for the thickness of the carpet tape (which is pretty thin stuff).

So my questions are:

1) why is the bit too high?

2) How can one set the bit height to get good results? In order to test fit the plate, you have to cut away the waste. Once you do that, I found it very hard to keep the baseplate of the router flat to the table top since less than half of it was on the table top - the router wanted to rock in. So my attempt to sneak up onto the right depth failed. I tried putting the waste back in so that the router had something to rest upon but it wasn't the same level as the table top. Plus I got skeert thinking that since it could move it would hit the bit and go flying.

I tried test settings on a piece of scrap only routing the edge but I found that testing the fit of just 1/2" edge of the plate was hard to do.

3) Is this REALLY the way to set the Pro-Plate (or any plate) into the table?  I've looked over several articles where people did this, but I don't have the same success as they did. The articles go into great depth as to how to make the template but give very little clue as to how to set the bit height.

Did they find a way to get the bit height set EXACTLY right so that the plate is level with the table top? Or did they take that 'fingernail catch" error and live with it?

Any advice would be appreciated.

 

Gregg

blopar's picture

Gregg, I would suggest you (post #169590, reply #1 of 14)

Gregg,

I would suggest you route the opening all the way through the top to the size of your plate, plus the thickness of a business card on one long and short side. Then on the underside glue pieces along the short side to create the shelf. To dial in the height of the plate you can put a drywall screw in each corner and raise or lower as needed.

Matt Kenny has a video in the shop series on building a router table that I think displays the installation that I described, I beleive John White had one a few years ago as well.

Saville's picture

I've seen that..... (post #169590, reply #2 of 14)

Hi blopar,

 

I've seen that technique in magazines and I guess I'll fall back onto that but I have some questions about that technique as well:

 

1) I have a 1/4" thick, aluminum plate. If I put a screw only at each of the 4 corners, will not the weight of the router bend the plate down?

 

2) When people use this technique, do they just let the plate rest on the screws? or do they also bolt the plate in place?


thanks,

 

Gregg

blopar's picture

1/4" aluminum plate (post #169590, reply #6 of 14)

Gregg,

You shouldn't see any deflection with the 1/4" aluminum pro plate. I have the rockler plate and haven't had any issues with it so far. Ralph makes a good point about the screws moving out of adjustment over time, I ran into that problem myself. My table isn't fixed in a cabinet or under a table, I clamp mine to my bench or outfeed table and pull the plate and router out with each use. To eliminate that issue I set 1/4" tee nuts in each corner with a hex bolt set to the height and a jamb nut on the under side to lock the bolt in place. I also set tee nuts in two corners to secure the plate to the table, I can't recall whether they are 1/4" or 10-24, I think they are the later.

epirnik's picture

Routing Ledge for Router Table Plate (post #169590, reply #3 of 14)

Hi Gregg,

FYI - Matt Kenney covered the process in detail in hist most recent Video Workshop:

http://www.finewoodworking.com/router-table-video-preview/

Episode 4 - Hope that helps!

Best,

Ed

Ed Pirnik
Senior Web Producer
Fine Woodworking

Saville's picture

Well....not really..... (post #169590, reply #4 of 14)

Ed,

It wasn't until episode 6 that he actually mounted the router in the top.

And he didn't go into any detail other than to say you use 4 screws and adjust them.

None of my questions were really answered - like the one about plate sag/using only 4 screws.  He just used 4 screws.


Gregg

RalphBarker's picture

leveling screws (post #169590, reply #5 of 14)

When I built mine, I used two adjustment screws on each of the four sides of the plate/lift. That distributes the weight over more area, and puts less stress on each brass insert, through which the adjustment screws extend. The rabbet on mine needed to be fairly narrow, due to other below-table elements of the lift. As a result, I had to use 8-32 machine screws for leveling adjustment, so the brass insert would fit within the rabbet.

Your design requirements might differ based on the geometry of your plate or lift.

I would not recommend using a single screw on each corner under any circumstance, however. Should any one of those screws vibrate loose during a routing operation (and, they eventually will), a potentially dangerous shift in bit position would result.

epirnik's picture

Oh God, you're right - it was (post #169590, reply #7 of 14)

Oh God, you're right - it was episode six. Fast hands at the keyboard.

Anyhow, that's the method I've seen on pretty much every shop I've visited in the last couple of years.

As far as plate sag is concerned - I have never seen it happen. IMHO, that short a length of aluminum (I'm assuming your plate is aluminum) isn't going to sag - but that's just what I've seen. Doesn't mean it hasn't happened to anyone out there.

It's a good topic- especially since I just scored a "new" used Woodpecker lift I need to set into my side feed table. One of these days....for now, I can only oggle at it in its box beside my desk here at the office.

Good luck!!!

Ed Pirnik
Senior Web Producer
Fine Woodworking

Imola's picture

I bought the plans and have (post #169590, reply #8 of 14)

I bought the plans and have watched the viedos quite a bit during construction. I have a Woodpeckers plate, not a lift and I'm going to use a Trition TRA001. I don't understand the need for the drywall screws when these plates come with leveling screws. That is my first question with a follow up being why the plate has to sit on a narrow ledge on the plate supports? Is there some reason you can't let it sit on 1/4" or so?

Is there a way to ask Matt a question directly? I don't see him as a member here.

RalphBarker's picture

drywall screws vs. machine screws (post #169590, reply #9 of 14)

I haven't watched the video, so I might be talking through my hat here. But, here goes.

Drywall screws are often used with MDF because of the coarse thread and relatively deep cutting action of those threads. In my opinion, however, machine screws in threaded inserts provide finer adjustments, and allow for the use of jam nuts.

The width of the ledge, it seems to me, depends on the overall design approach. For example, if using threaded inserts or T-nuts, you might need a wider ledge - more like 1/2" or more, depending.

The flip side of that coin, however, is the size and fit of the router, once mounted on the plate. You don't want the edge of the ledge interfering with sections of the router or the lift. The same considerations affect the overall thickness of the table itself. You don't want a nice, thick table blocking access to router adjustments.

Imola's picture

All of your comments are well (post #169590, reply #10 of 14)

All of your comments are well taken, make sense, and I've have also thought of some of them. I can't see why the ledge even with the big Triton can't support the router with even up to 1/2".

The only spot your off on is the MDF. The plans use hard maple as the support, so you could use fine-threaded inserts. Good idea and I may do that. With such a nice design I just didn't understand using drywall screws to set the plate on, especially when it was mentioned they will vibrate loose, and I think they wouldn't even provide a very flat, stable place for the plate leveling screws to sit on.

An added question for me is how high will be a comfortable distance? I have never used a router table. I'm 5'6" and like workbenches to be a couple inches lower than average. But I'm thinking a router table is not a workbench where you need power and leverage. Depending on what size casters are used and following Matt's plans, the table is almost 37".

RalphBarker's picture

Table height (post #169590, reply #11 of 14)

Good question. A final height of 37" strikes me as a bit high. Mine is 33" high, and I, at 5'8", find it comfortable. For comparison, Rockler/Benchdog tables are 32" high.

Westchester's picture

Height (post #169590, reply #12 of 14)

I made mine the same height as my table saw so it doubles as an outfeed table when cutting larger boards.

SA

Imola's picture

Why Matt didn't install a (post #169590, reply #13 of 14)

I am wondering why Matt didn't install a miter/T-track in the router table top. Having never done serious routing myself, I thought I would need it and bought one to install. What's the consensus on how often it's used on a router table?

RalphBarker's picture

Miter track (post #169590, reply #14 of 14)

I intalled a miter trakc on mine without really thinking about it. After doing so, it dawned on me that a sled designed to run against the fence would work just as well.

The utility of either approach depends on how often one does end-grain routing.