Cutting my first rabbet into hardwood, any tips for success?

[Chris Lukowski]

I'm working on a small project (41"x17" changing pad tray for nursery) that will call for my first-ever use of a router and need some pointers so I don't mess it up. The sides of this tray will be made with maple 1x4s and I need to cut out a 3/8" rabbet on the bottom to insert a plywood bottom. The plan is to assemble the sides to form a rectangle and route the rabbet on the inside of this assembled piece with a 2.5HP router (either with a fixed base or a plunge base. One tip that I had heard was to not remove more than 1/8" of wood at a time or else the cut might get choppy or burned, especially in hardwood. That seems to suggest that I either adjust the width to 1/8" (with bearings or some other means) and cut at full depth (1/2" to match the plywood), OR cut at full 3/8" width and use the plunge base to start with a shallow depth and work my way up (if rabbet bits even play nice with that strategy). I believe for both options I would be using the router at max speed since it's a sub-1" cut, correct? After the rabbet is cut I was going to glue in the plywood and hold it in place with a few hand hammered brad nails as I don't have a nail gun at the moment. Any advice would be greatly appreciated!

[Robert Engel]

You should be able to do that in one pass is you go slow. Wobbling will be an issue better to do this in a router table with a straight cut bit. (I cut most of my rabbets on the table saw.)

I think the trick is learn to do climb cutting to minimize blow out.

You might also consider just cutting a 1/4" wide groove and put the rabbet on the bottom.

[Chris Lukowski]

Thanks Robert! I -do- have a dado stack for my table saw and haven't yet bought the router or bits, and I initially didn't consider cutting the rabbet using the dado method because I didn't want the rabbet to go from end-to-end on the boards. Seems like it would be tricky to get the groove to start and stop at particular points and also to deal with the rounded edges from the dado blade. I unfortunately don't have enough cash at the moment to get a router table set up so if I routed it would have to be freehand.

[Prashun Patel]

If you cut a rabbet on the bottom then nail in the plywood bottom from the bottom, it is only supported by glue and nails.

If strength is a concern for you, a stronger design would be to make a small rabbet on the bottom of your plywood bottom so that you create a tongue on your bottom. Then you route a small groove 1/2" or so from the bottom in the sides of your tray. The bottom then slides into that groove. Add glue if the base is plywood so that it improves the ability of the sides to resist shifting and racking.

If you are set on doing as you plan (not saying it's uncommon!) then I would take care to pre-drill holes for the brads. You'd hate to blow out your sides.

[Charles Lent]

Only climb cut as a second pass to smooth the cut. Trying to climb cut on the first pass will be a disaster. you will damage the project, probably the router and the bit, and possibly even you. Only climb cut when taking very very light cuts and you probably will not need to do this for this project. 3/8" is NOT a very light cut. I would use either a table saw with a 3/8 or wider DADO blade with the excess width buried in a sacrificial fence, or a 3/8 rabbeting bit with a bearing in a router for this 3/8 rabbet. To avoid blow out, use a larger diameter bit of a diameter at least 2X if the width of the rabbet. If a bit is used with no bearing, a router fence is required, but a large diameter bit is even more important when using the router fence, to avoid blow out. Using a router table is best to avoid wobbling, but an offset base with a handle attached can help you keep the router from wobbling.

Charley

[Chris Lukowski]

Hi Prashun,

The bottom won't be load bearing during use so the 3/8" rabbet into the side walls of the tray from the bottom seemed like the simplest solution. This tray will sit on top of a dresser full time to hold a foam baby changing pad and accessories, as depicted in the following image:

354600

[Ellen Benkin]

Whatever method you use (table saw or router) practice on some scrap material to get the "feel". This is not a difficult cut but it does take practice. I would rout each piece before assembly and use a router table for safety but I know woodworkers who do it after assembly with excellent results.

[Prashun Patel]

In this case, I suggest you route the rabbets before assembly.

Depending on how the sides are joined, you will have to make 'stopped' rabbets on two of the sides, but if that's beyond your ability, you can cut little plugs and nobody will be able to tell once assembled and stained and finished.

[Brian Tymchak]

I know you didn't ask for this kind of feedback but I'll offer it anyway. IME, plywood is not uniformly flat. If the plywood bottom is to be flush with the bottom of the side rails, the tray will likely end up wobbling or able to spin on a high spot in the plywood. I would hold the plywood bottom up a bit from the bottom of the rails so that the rails are what supports the tray. So, in this case, you would end up cutting a groove vs a rabbet.

[Pat Barry]

Only climb cut as a second pass to smooth the cut. Trying to climb cut on the first pass will be a disaster. you will damage the project, probably the router and the bit, and possibly even you. Only climb cut when taking very very light cuts and you probably will not need to do this for this project. 3/8" is NOT a very light cut. I would use either a table saw with a 3/8 or wider DADO blade with the excess width buried in a sacrificial fence, or a 3/8 rabbeting bit with a bearing in a router for this 3/8 rabbet. To avoid blow out, use a larger diameter bit of a diameter at least 2X if the width of the rabbet. If a bit is used with no bearing, a router fence is required, but a large diameter bit is even more important when using the router fence, to avoid blow out. Using a router table is best to avoid wobbling, but an offset base with a handle attached can help you keep the router from wobbling.

CharleyHe means, if using a hand held router, to make your cuts from left to right, not right to left. Right to left cutting will make the router bit want to pull the router into the work and effectively the bit will want to climb up the wood. Generally you don't want to cut right to left when removing material as this can become dangerous / exciting depending on your point of view. If using a router table (recommended) then feed right to left, not left to right

[Chris Lukowski]

I know you didn't ask for this kind of feedback but I'll offer it anyway. IME, plywood is not uniformly flat. If the plywood bottom is to be flush with the bottom of the side rails, the tray will likely end up wobbling or able to spin on a high spot in the plywood. I would hold the plywood bottom up a bit from the bottom of the rails so that the rails are what supports the tray. So, in this case, you would end up cutting a groove vs a rabbet.

OR could I alternately cut the rabbet 1/16" or so deeper than the plywood so that it's in a slightly raised position? Or would the ever so slightly raised position cause a problem with the weight of a baby on top of it, even if the glue-up is reinforced with a dozen or so brad nails?

[Chris Lukowski]

So just so I'm clear, is the consensus that assembling the rails and routing out the rabbet in a single circular motion on the bottom edges of the boards a bad idea?

[Prashun Patel]

I don't think it's a bad idea. You just have to be careful of your direction, and you have to be careful not to tip. That gets tricky as the bit depth protrudes further from the base with each pass.

Also, you'll still require chiseling out the corners or truncating your plywood bottom.

[Pat Barry]

So just so I'm clear, is the consensus that assembling the rails and routing out the rabbet in a single circular motion on the bottom edges of the boards a bad idea?
Lets say you do the rabbet as you described. As Prashun noted you will need to chisel out the rounded corners to accommodate your rectangular panel. I'd much rather see the panel then captured with a full perimeter support (not just nails). For example another set of added on retainer pieces. I'd want to maximize the bottom side support with screwed and glued on supports. Who's to say someone doesn't try to carry the baby in this nice little basket? It would be a sad day indeed when the bottom let go.

[Jerry Miner]

You don't say how you intend to join the corners of this tray.

If you miter the corners, you can pre-cut the rabbets (or grooves) in the sides before assembly--and use the table saw/dado set.

If you use dovetails, or box joints, or butt joints, you have the choice of pre-cutting then filling small spaces with wood plugs, or cutting the rabbet after assembly with the router (as in your original proposal).

If you rout the rabbet after box assembly, yes, light cuts, several passes (easier, IMHO to keep one bearing on and sneak up on final depth in small increments.) You will get an idea of chip-out issues with the first pass, and can consider climb-cutting for subsequent passes. I don't generally recommend climb-cutting for beginners---and it sounds like you don't even have a router yet--- so be very careful here, as climb-cutting can be surprising and dangerous.

Be sure to clamp the box firmly to a stable surface while you rout. Do NOT try to hold the work in one hand and the router in the other! Balancing the router on the edge of a 3/4" thick board can be tricky--and even trickier as that board gets reduced to 3/8 after the first pass. Consider an "outrigger" or a spacer or a wide sub-base to help keep the router vertical

[Chris Lukowski]

I'd want to maximize the bottom side support with screwed and glued on supports. Who's to say someone doesn't try to carry the baby in this nice little basket? It would be a sad day indeed when the bottom let go.

Well my intention is to secure the tray to the dresser via a bracket screwed into the backs of both or some other means, so it's not going anywhere for a while. I'm trying my best not to over-engineer it too. I would have thought a simple tray with a plywood bottom wouldn't have been too complicated.

[Stew Hagerty]

Here's the rule of "Thumb" for using a router... Point the thumb of your right hand (palm down) at the edge you plan on routing then extend your forefinger and that is the direction you need to go.

[Chris Lukowski]

You don't say how you intend to join the corners of this tray.

If you miter the corners, you can pre-cut the rabbets (or grooves) in the sides before assembly--and use the table saw/dado set.

If you use dovetails, or box joints, or butt joints, you have the choice of pre-cutting then filling small spaces with wood plugs, or cutting the rabbet after assembly with the router (as in your original proposal).



You know what? I think I just might do this. I wasn't going to miter the corners originally, thinking I would have an easier time with pocket screws and plugs since the tray would be painted. I didn't even think of how easy it would be to run the dado through my table saw and miter the corners to hide the groove. That would just leave the decision to make it an open bottomed rabbet or a groove with 1/8-1/4" lip at the bottom to help support the board. I could save $250 by not buying the router too! I already have the table saw, dado set, and miter saw. Sweet!

So in addition to letting me know what you think about that, if I go sans-router how should I ease the edges of the boards? I was going to do that with a small roundover bit but honestly I'm not looking for a visible edge profile so much as a uniform-ish softening of the hard edges. Should I just do that with a sanding sponge or ROS? I don't own any planes just yet unless that really is the preferred tool for this sort of thing.

[Pat Barry]

Here's the rule of "Thumb" for using a router... Point the thumb of your right hand (palm down) at the edge you plan on routing then extend your forefinger and that is the direction you need to go.
I need a picture - this doesn't make sense

[Pat Barry]

Well my intention is to secure the tray to the dresser via a bracket screwed into the backs of both or some other means, so it's not going anywhere for a while. I'm trying my best not to over-engineer it too. I would have thought a simple tray with a plywood bottom wouldn't have been too complicated.
If its going to be attached to the dresser, then by all means do what you were thinking. I would feel better still with screws instead of nails and I would glue it to boot.

[Roger Feeley]

I made this for my grandson. Basically you just need a frame to keep the changing pad from sliding off of the top of the dresser. I did it with mitered and splined corners and no bottom at all. I let the dresser top be the bottom. I made the side of the frame that goes on the back side wider so it extends down and can be screwed to the back of the dresser. In my case, I didn't have the dresser at hand so I also made a set of shims so I could move the frame back a bit. When the baby doesn't need the frame anymore, we undo three screws and no one will ever know it was there.

Since I mitered the corners, I knew that the joints would be weak. So I cut splines. I was staining and varnishing and I made more splines than I needed for looks. You are painting so it's even easier. If you miter, I highly recommend splines.

[Jerry Miner]

.... if I go sans-router how should I ease the edges of the boards?

My favorite tool for any particular operation is the tool I already have.

I have several routers, and I usually do round-over operations with a router--- but if I didn't own a router, I would simply use a sanding block or rasp/sanding block combination.

But if you want to use this project to justify investing in a router, by all means go for it!

[Stan Calow]

Apologies if I missed this in the discussion. Is your plywood a true 3/8" or is it nominally 3/8"?

[Lee Schierer]

So just so I'm clear, is the consensus that assembling the rails and routing out the rabbet in a single circular motion on the bottom edges of the boards a bad idea?

You can route the rabbet with the drawer assembled. However, you will end up with round inside corners that you will then need to clean up with a chisel. Using a router requires a certain level of care and a close inspection of each piece of wood. Wood grain generally is not straight where it meets the edge of the board. Sometimes routing in the conventional manner will result in chipping of the wood you hoped would be left after making the cut. Sometimes climb cutting is necessary and is safe as long as you understand the differences in technique that are required when making a climb cut. When climb cutting light cuts and strong control of the router and piece being cut are absolutely essential. The first pass with any router bit on any edge should be a very light cut. Taking a 3/8" cut is asking for major chips or tear out. Taking several more light cuts and ending up with a nice smooth tear out and chip free cut is by far preferable to making one aggressive cut and ending up with a ruined piece of wood.

A better drawer design is to insert the bottom in a dado rather than a rabbet. Drawers made this way are much stronger.

[Chris Lukowski]

Apologies if I missed this in the discussion. Is your plywood a true 3/8" or is it nominally 3/8"?

The plywood itself is standard 1/2" birch, and that would have been the height of the rabbet plus another 1/16" or 1/8" to accommodate for irregularities in the plywood. 3/8" would have been the lateral depth of the rabbet in each 1x4 board, which would be 1/2 way in. Now that you mention it, whether I make an open bottomed rabbet or a dado groove, IS 3/8" the depth into the 1x4 (3/4" actual) that I should be shooting for, or is that too deep?

[Jerry Miner]

3/8" is the typical cut for a rabbetting router bit. If you do the cut on the table saw, 3/8" would work fine.

IIWM, I would probably go a little deeper ( like +/- 1/2"), to make it a little easier to drive the nails without "nail blowout"-- but since you are hand-nailing anyway, and you will need to pre-drill your nail holes, it doesn't matter much.

BTW-- you might find it as easy--and stronger-- to use screws rather than nails.

[Chris Lukowski]

That's funny, I never would have guessed to pre-drill holes for brad nails. If you think predrilling is necessary either way, maybe I will just screw it in. Is there any particular type of screw that should be used? I have a variety of Spax coarse thread construction/wood screws, with perhaps the #6 1.5" ones sounding like a good choice for screwing 1/2" plywood into the edge of a maple 1x4. Would they work well for this or should I look for fine thread?

As for the depth of the rabbet, I could easily go to 1/2". I just didn't want to make it so deep that it weaken the remaining material.

[Jerry Miner]

Your #6 x 1.5 coarse thread would work (with a proper pilot hole/clearance hole/countersink).

The "ideal" screw for me would probably be a #6 x 1 1/4 fine thread, but no harm in using what you've got.

[mark mcfarlane]

... if I go sans-router how should I ease the edges of the boards? I was going to do that with a small roundover bit but honestly I'm not looking for a visible edge profile so much as a uniform-ish softening of the hard edges. Should I just do that with a sanding sponge or ROS? I don't own any planes just yet unless that really is the preferred tool for this sort of thing.

Hand sanding the edges with sandpaper will work fine and will only take a few minutes. If you have a sponge to back the paper thats fine, or use your finger tips. If you want to remove a lot of material start with courser paper, otherwise 120 or 150 will ease these edges fine, then finish up to the same grit as the sides of these rails.

[rudy de haas]

"a few hand hammered brad nails" ?

Is it really possible to hammer a brad in by hand? I know I can't do it...

In your place I'd bite the bullet on this and go all the way out to the corners with the rabbet so I could use the table saw to make them and then clean up the corners after wards.

However.. if you know for sure that you can hammer a brad (or, better, borrow a brad nailer for an hour) then what I did to make router cuts that start and stop in arbitrary places was (note past tense, I have a shaper now :) ) to clamp the workpiece down with a sacrificial piece of the same thickness beside it and then clamp two strips one router width apart centered on the cut line. Two smaller bits of router width then get clamped in place near the ends half a router width from where I want to start/stop. With that in place, a plunge router lets you start close to one end of the slot, cut to the stop, and then cut all the way to the other stop with no risk of going off the center line. (Note: the surface has to be fairly smooth for this to work well, so plane/sand a bit first).