Dado in Formica top- best way???

[Malcolm Schweizer]

I am building a T-Track table and the top will be Formica. I need to route lots of dadoes for the t-track. Here are my options:

Add Formica first, then route dadoes with a router.

Easier
high risk of tear-out of the Formica on one side of bit.


Add Formica first, then use a dado blade.

Easiest
Hard on the blade
Faster


Dado first, then add Formica, then flush trim the Formica in all the dadoes with a router.

Hardest
much less chance of tear-out
Time consuming



I am leaning towards option 3. I would rather do the dadoes on the table saw for accuracy. I just have to be sure the flush trim bearing is smaller than the dado.

Open to suggestions.

[Kent A Bathurst]

True panel saws have a scoring blade in front of the cutting blade. It runs the opposite direction - a climb-cut - but only makes a very shallow cut - 1/64"? 1/32"?

You can do the same thing on your table saw with a good crosscut blade. Set it very shallow, and run the top through it backward, Yep - start at the outfeed side of the saw and push it to the front.

THe very shallow cut takes the climb-cut factor pretty much out of hte equation - you are scoring the very top layer of the surface.

Then route it, and your edges will stay clean.

Or - get a pack of new blades for your carton knife, and start taking gentle scores until the trazor blade line gets partway through. "Gentle" so you stay on track with your straightedge guide, and don't wander.

[Rod Sheridan]

Malcolm, what makes you think it will be hard on the blade?

I would cut it with a dado in the saw..................Rod.

[Jamie Buxton]

On option 3, a flush-trim bit has a bearing on the end, and a screw head beyond that. The actual cutting edge may be a good half inch from the end of the bit. That is, you might not be able to get it into the trench to trim the formica.

I'd do option 2. Unless your tools are dull, there isn't much chance of chip-out along the edges. And if there is, who cares? A little chip-out won't change its functionality at all.

The advantage of option 2 over option 1 is that you can fuss with the dado head until you get its width exactly right. Then you make all your dados with one pass per cut. With a router, you're likely to need two passes to get the dado width exactly right. Every time you do two passes, there's risk of a mistake giving you a tapered dado, or one that's too wide.

[Mark Bolton]

With option 3 Id venture to guess you'd have a hard time keeping the top flat applying the laminate over the dados. Im not sure why your worried about option 1 as it would be my first choice. The dado/TS option has just as much likelihood of blowing out a piece of laminate as any. I would almost guarantee you'd have at least one lousy cut if you have many to do.

I would much rather use a router bit of lesser diameter than the slot I needed and make it in two, or three passes if you were really worried (I wouldnt be). I would simply plow my first pass, then move your jig/straightedge over the needed amount, and make the next pass to get the width exactly what you want. If you were super terrified of a non perfect edge, plow a pass up the center, and then one down each side to get it finished.

Scoring on a slider or even trying to attempt it on a TS wouldnt give you the result youd want I think. The scoring blades on a slider are set slightly wider than the dado so they leave a very little step in the top of the dado. This isnt really seen in most casework but on a machine top it would be.

[lowell holmes]

I would experiment on scrap. It's not worth taking a chance blind.

[Malcolm Schweizer]

Thanks for the replies. A few answers:

Why do I think it will be hard on the dado? Formica is hard stuff and I am making 6 dadoes in four tops for a total of 24 dadoes 2' long each, plus more dadoes on the sides.
Multiple router passes- I could do this. It's just that part of the project is building a router table. I could build the router table first and do it with the new table, but boy that is a lot of room for error. Lots of passes and lots of adjustments. It is an option. I would probably first try the 3/4" (full width) bit first and see how it worked.
I did not consider the screw at the end of the bearing of the flush trim bit. D'oh. That's probably out.
Scoring with a razor was another option I forgot to mention. Lots of laying out but certainly would work.


Here is the project so you see why I am thinking this through. If it was two or three dadoes I wouldn't really be concerned. All tracks on outer edge are 4" on center from the edge. The middle track 12" OC. This way I set the fence once, make all outer passes, set again, make middle passes. Oh- forgot to say I am making two of these. Each has two 24" tops.

[Malcolm Schweizer]

I would experiment on scrap. It's not worth taking a chance blind.

Certainly will do that, but wanted to throw it out to see if anything g can be eliminated up front, or if other ideas were out there. My experience with Formica is only making simple countertops.

[Jerome Stanek]

I would cut the dado first and use a solid flush cutter no bearing just a solid ball nose on it. We dothis all the time.

http://www.amazon.com/PORTER-CABLE-43216PC-4-Inch-Carbide-Router/dp/B00004Y78S

[Dave Kirby]

I would cut the dado first and use a solid flush cutter no bearing just a solid ball nose on it. We dothis all the time.

http://www.amazon.com/PORTER-CABLE-43216PC-4-Inch-Carbide-Router/dp/B00004Y78S

Yep. +1...^^^THIS^^^^

[Malcolm Schweizer]

I would cut the dado first and use a solid flush cutter no bearing just a solid ball nose on it. We dothis all the time.

http://www.amazon.com/PORTER-CABLE-43216PC-4-Inch-Carbide-Router/dp/B00004Y78S

boom! Didn't know these even existed. Thanks.

[Mark W Pugh]

I have done #2 numerous times, no problems. Hard on blades?? I wouldn't over think this.

[Walter Plummer]

We use this one from Amana. It is made for dados. http://www.amanatool.com/products/router-bits/trimming-router-bits/solid-carbide-panel-pilot-flush-bevel-router-bits/51204-solid-carbide-short-flat-pilot-for-dado-clean-out-dado-cleaning-flush-trim-1-4-dia-x-1-4-x-1-4-inch-shank-x-1-flute.html

[Tom M King]

3. It shouldn't take that long, and for me it would be because I have the bits to do it with, without having to wait for another one to get there.

[Dave Cullen]

I've been through this recently. I added a miter slot to a small table and a t-track to a fence that had Formica already on them. My dado blade chipped out the Formica badly on the table, so I used a router bit to do the fence slot - MUCH better. Of course this could be because the dado set is less than stellar. If the table hadn't been laminated already I'd definitely do the grooves first and flush trim as has been suggested.

[Art Mann]

I have installed a lot of plastic laminate and I have never had a problem with method 1. Formica won't "tear out" and i just haven't seen any chipping. Just you use good technique and a good router guide. There is nothing wrong with method 2 either. Unless you cut laminate on a regular basis, the dado blade won't dull enough to tell any difference. I would rule out the third method based on the fact that it is too much trouble for no additional benefit.

Remember - the trimmed edge of the laminate will be razor sharp and you are going to want to put a bevel on it anyway. That will take care of any minor chip out from the dado blade.

[Ole Anderson]

I used #1 on my router table, only problem is that I didn't back up the edges, which were also Formica, so I blew out some of the edges as the router bit exited the top.

[Malcolm Schweizer]

I used #1 on my router table, only problem is that I didn't back up the edges, which were also Formica, so I blew out some of the edges as the router bit exited the top.

So I'm getting off a plane and checking my emails and get the notification that there is a reply to my post. I start reading, "I used #1 on my router table..." And I forgot that I had listed options 1, 2, and 3, and at first I think, "Why is this guy telling me he peed on his router table?" It was a long flight and I was tired! Hope you get a laugh at that. I did.

[Brian Henderson]

Of course, you could always just rout the tracks into the table, then cut the formica to size around the cuts and laminate each separately, then you wouldn't have to worry about chipping the formica at all.

[Bill McNiel]

Method #1.
I just redid my TS/Router Table surface with a torsion box top covered in P-Lam. Used a cheap" Rockler 1/2" diameter hinge template bit with top bearing and homemade templates for the Router Lift cutout and TS runou slots. No chipping, no hassels, simple, easy and great results.

[Ole Anderson]

So I'm getting off a plane and checking my emails and get the notification that there is a reply to my post. I start reading, "I used #1 on my router table..." And I forgot that I had listed options 1, 2, and 3, and at first I think, "Why is this guy telling me he peed on his router table?" It was a long flight and I was tired! Hope you get a laugh at that. I did.

That is EXACTLY why I do not recommend a cast iron top on your router table!:o

[Dave Cullen]

This is the result of using my dado blade through a Formica top - I hope yours comes out better.


304759

[Anthony Whitesell]

If you cut the dadoes first then put on the formica and do a clean up pass, you will have to be very accurate with your measurements to get the depth right for when the t-track is installed. I would suggest putting the formica on first then cutting the dadoes so you can fine tune the depth. When I built my router table, I put the formica on first, then used a router with a spiral down carbide bit. Formica is not that thick and isn't particularly hard on the bits. If you are using MDF or particle board for the substrate (assumption as those two are the flattest sheet goods available), the substrate material will be far more abusive on the bits than the formica.

[Art Mann]

This is the result of using my dado blade through a Formica top - I hope yours comes out better.


304759

I have never seen anything quite like that. The fact that part of the cut didn't chip out leads me to wonder whether the material was really well glued down well. Another possibility is that the fence isn't parallel to the blade and the teeth are grabbing the material on the "down side" of the blade travel. Is the dado blade you were using sharp?

[Dave Cullen]

I have never seen anything quite like that. The fact that part of the cut didn't chip out leads me to wonder whether the material was really well glued down well. Another possibility is that the fence isn't parallel to the blade and the teeth are grabbing the material on the "down side" of the blade travel. Is the dado blade you were using sharp?

Table saw fence is dead nuts. The dado is new, but a cheap model from HD. Perhaps a better one would have fared better. This is a 1" groove, so I had to take 2 passes. The slot for a T-track in the router fence I did with a 2 flute router bit and it came out perfect. Hind sight, etc..

The chips have been filled in with auto body putty. Not pretty, but oh well.

[Mark Bolton]

I have never seen anything quite like that. The fact that part of the cut didn't chip out leads me to wonder whether the material was really well glued down well. Another possibility is that the fence isn't parallel to the blade and the teeth are grabbing the material on the "down side" of the blade travel. Is the dado blade you were using sharp?

Chipout in plam with any type of circular saw is a fear for anyone who has had to cut plam period. The only way you can even have a hope of it leaving a flawless cut is if your tooling, and tool, are so dead on that you may as well be in a nasa engineering facility. It may work sometimes and it may work horribly other times.

There is a reason why top shops work tops with routers and its not because they aren't smart enough to use a TS. Its because they are smart enough NOT to.. ;-)

[Art Mann]

I have only used a dado set once to cut laminate and that was the exact same application that Dave used it for. I didn't have any problems and certainly didn't experience the disaster that Dave did. There has to be something else going on besides inappropriate cutting tools. As far as using a table saw goes, I can't count the number of times I have ripped counter top material with a plastic laminate surface and never saw anything like that. I have also successfully cut it with a track saw. In fact, that is the reason I first bought a track saw. About a year ago, I bought new counter tops for a remodeling project directly from a company that manufactures them. They were using a table saw in their shop. They were also using what looked to me like a giant radial arm saw. I can't imagine they are that unusual.

[Mark Bolton]

I have only used a dado set once to cut laminate and that was the exact same application that Dave used it for. I didn't have any problems and certainly didn't experience the disaster that Dave did. There has to be something else going on besides inappropriate cutting tools. As far as using a table saw goes, I can't count the number of times I have ripped counter top material with a plastic laminate surface and never saw anything like that. I have also successfully cut it with a track saw. In fact, that is the reason I first bought a track saw. About a year ago, I bought new counter tops for a remodeling project directly from a company that manufactures them. They were using a table saw in their shop. They were also using what looked to me like a giant radial arm saw. I can't imagine they are that unusual.

In my experience, the problem with any circle blade in Plam is anyting off, and I mean anything, can result in a less than desirable edge. This can be dull, misalignment, blade flutter, feed rate, and so on. Blade flutter to me is the major issue. If the blade begins to flutter at all in the cut it will blow out the back side of the cut (as the tooth leaves the work on a good down, or enters on a good up). Its just a risk. It can work well over and over and then all of the sudden you have disaster. The tried and true method is a router. Its why wen you lay up a top and prep the edge for wood, plam, whatever, you prep it with a 2" top bearing straight bit and a straight edge. You dont feed it across the saw for fear of chipping out the top. Its the only way to get a dead clean flawless face and edge.

Just my experience.

[Art Mann]

If you want to cut a laminated counter top to fit in a kitchen, a router is useless as a cutting tool. Perhaps I have just used saws with circular blades long enough that I know how to do it right. I just don't have the kind of problems you are describing. I am not unique in my skills. I have seen many, many other people cut laminated tops with a table saw without difficulty. The top manufacturer I do business with does it all day every day.

I just read your post again about using a 2" (I presume cutting length) router bit and I can honestly say I have never seen or even heard of anyone do it that way, professional or amateur. I am sure some shops use a router to do it but it would be a $40,000 CNC router with a 10hp spindle. That is not meaningful to our discussion. Here is the procedure I have seen over and oner again for doing flat tops like a router table. (1) Cut the substrate to size on a table saw. It could be plywood, MDF or cabinet grade particle board. (2) Cut the laminate material to rough size using a table saw. The quality of the cut doesn't matter because all the edges will eventually be routed away. (3) One, at a time laminate the edges of the material using solvent based contact cement. I have found the water based stuff to fail occasionally so I don't use it. (That may have been Dave's problem). Use a trim router and a flush trim bit to cut the laminate flush with the substrate. (4) Laminate the top the same way as the sides but instead of using a flush cut bit, use a bevel cut bit to blunt the sharp edge that a flush trim bit leaves. (5) If I need to resize the material after the fact, I just use a table saw and an appropriate trim blade. If this edge will be exposed, I will run over it with the bevel bit so as not to leave a sharp edge. If I need a dado or groove cut into the surface, i will use either a router with a straight edge (preferable) or a quality dado blade. If the blade (or router bit) leaves any chip out, it will be removed with a trim router and bevel bit.

[Mark Bolton]

If you want to cut a laminated counter top to fit in a kitchen

Your sequence is no different than anyone else for assembling a square edge Plam top. No disagreement there. But the OP's question, and my responses, were not with regards to cutting substrate material, or fitting a top into a space. Those scenario's dont have a tremendous concern for a very clean, very precise, visible edge. Fitting a top into a kitchen is nothing with a skill saw. The cut edge is more than likely going to be caulked in, covered with a side splash, belt sanded to a scribe, or some other treatment. The OP's scenario is cutting into the field of a finished top, in one shot, and having it fit, and look, as close to perfect as possible. I cut Plam tops all the time with a circular saw, sink holes, scribes, and so on, but even in those situations (sink holes especially) chipping is nearly always common but who cares? The sink flange or side splash is going to cover it. If I have a dead tight scribe that isnt going to get covered it gets cut close and belt sanded in. If I have to make a finished cut in the field, for instance where an end cap is going to be installed (very rare), I cut from the back of the top, again to minimize chipping. Cutting from the back of course isnt possible with a dado.

The router bit method I mentioned has been a top building method for many many years when applying an edge material (not Plam) after the top surface has been laminated. Its been the practice for far longer than todays times of 40K and up CNC's being so common. Even now though there are countless top shops that dont even implement CNC. Its the most common way I know of (without a CNC) to flawlessly detail an edge for further treatment when not having Plam on the edges (edge treatment goes on after). After laminating the top its not uncommon for the edge to be less than perfect or have some contact residue even after trimming. This can be a pain in the butt when your applying a non-plam edge which goes on last (wood, metal, etc) After Plam is on the top and trimmed, the edge is routed perfectly with a straight edge or curved template and top bearing bit. No residue, dead clean, dead square. I referenced this only because even if the top were straight, you would never run the top across a TS for fear of blowing out the Plam on the top. It would be almost guaranteed. Not to mention a lot of tops are just too cumbersome to handle on the TS at that stage and one bobble and your lost.

The chipping in the top cut with a dado blade posted in a previous reply would in my opinion be more common than not with for most people even with ideal equipment. There are just too many options for something to go wrong.

[Malcolm Schweizer]

Thanks for all the replies. I am leaning towards doing the dadoes first, then routing with the solid bearing flush trim bit. I feel more comfortable getting the dadoes all straight and correctly spaced on the table saw than I do on a router table. (better fence and larger surface on the saw- I think it will just be overall easier) I do not mind running a trim router around every edge afterwards. I will just use a scrap piece of laminate to gauge the depth so that once I glue the laminate on the t-track will be flush.

[Edward Oleen]

Think about this:
(1) Cut the dados
(2) Cut the Formica into the desired strips to fit between the edge and the first dado, and between the dados.
This way you'll be gluing up smaller pieces of 'mica, and the gluing won't be so critical. Just make sure your strips are just a little bit oversized, so you have something to trim.
(3) Then, and only then, use the Amana solid rim bit to clean up the overhang into the dados.

This way may be a bit more work, but I think it is a bit safer, especially if you have any question about chipout in the 'mica. If, in cutting it, you do get chipping, if it is less than the overhang amount you will remove it when trimming to final size