# Adding a miter slot to a phenolic top



## Danimal61 (Dec 13, 2009)

Just received a new phenolic router top from Jointech, on sale, and would like to add a miter slot (t-track). I am unclear as to the method for cutting a slot in a phenolic top. Looking for some input.

Thanks

Danimal063


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## Cherryville Chuck (Sep 28, 2010)

You can do it with a straight bit, spiral bit or dado on the table saw. Keep in mind that for it to work your fence has to be absolutely square to the table which is unnecessary for most other operations. I use a sled instead. It is always square to the fence no matter the fence orientation. Actually, I usually just use a square piece of mdf and push my piece past the cutter with it which has the added advantage of helping to prevent blowout on the backside of the piece.


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## bobj3 (Jan 17, 2006)

Hi Dan

I will suggest you just let it be that stuff is a night mare to work with 
You will need a GAS mask if you do it. 

==



Danimal61 said:


> Just received a new phenolic router top from Jointech, on sale, and would like to add a miter slot (t-track). I am unclear as to the method for cutting a slot in a phenolic top. Looking for some input.
> 
> Thanks
> 
> Danimal063


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## Flint54 (Sep 26, 2011)

That is very tough material to work with. I have had a lot of experience in working with it when I was in the military. One key factor is cutting it at a slow speed to keep from burning the material and melting it also on your cutting tools. Slow cutting speed and slow feed are key. Neither a router or a table saw will allow for the speeds that you should use. I would recommend that you make your table in a laminated setup with the miter slot sandwiched between segments of the material all adhered to a base substrate. Lot more work but would be the best way IMO.


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## wbh1963 (Oct 11, 2011)

I like the way your mind works. That technique wouldn't weaken the stability of the existing top, though it would reduce the maximum bit height above the table.




Flint54 said:


> I would recommend that you make your table in a laminated setup with the miter slot sandwiched between segments of the material all adhered to a base substrate. Lot more work but would be the best way IMO.


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## Flint54 (Sep 26, 2011)

You could do a cut out on the base material and then mount the router to the phenolic. Then you would still have full depth control on the bits.


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## billg71 (Mar 25, 2011)

I've never been able to figure out why you would need a miter slot in a router table. Why weaken the table when you already have a perfectly good fence to reference off of?

Think about it....... 

HTH,
Bill


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## KenBee (Jan 1, 2011)

billg71 said:


> I've never been able to figure out why you would need a miter slot in a router table. Why weaken the table when you already have a perfectly good fence to reference off of?
> 
> Think about it.......
> 
> ...


This is something I have thought about and is something I don't fully understand. I don't think I could function without the miter slot or T-Track in my table. I have a Woodpeckers Super Fence but it is by no means a cure all for every router table procedure. The T-Track is handy for attaching feather boards which I use religiously, on both top and sides. The miter slot is handy for keeping cuts at a true 90 degrees or other angles when needed using a miter gauge. My box joint jig relies on the miter gauge for its proper use. I also reference my fence location off my Miter Slot, in particular for jointing operations. The outfeed side of the fence is adjustable so I set it with a dial indicator attached to a section of Miter Track.

Please explain to me how they weaken the table considering both are rigid sections of aluminum extrusion. If anything they would help maintain the rigidity of the table top in my view.

Just my thoughts on this often approached subject matter.


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## bobj3 (Jan 17, 2006)

Hi

Just one more way to add a miter slot to the top without cutting the top up.


Mini T-Track / Standard Miter T-Track
Dual Combo Track

http://www.ptreeusa.com/ttrackproducts.htm
===


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## billg71 (Mar 25, 2011)

Ken Bee said:


> This is something I have thought about and is something I don't fully understand. I don't think I could function without the miter slot or T-Track in my table. I have a Woodpeckers Super Fence but it is by no means a cure all for every router table procedure. The T-Track is handy for attaching feather boards which I use religiously, on both top and sides. The miter slot is handy for keeping cuts at a true 90 degrees or other angles when needed using a miter gauge. My box joint jig relies on the miter gauge for its proper use. I also reference my fence location off my Miter Slot, in particular for jointing operations. The outfeed side of the fence is adjustable so I set it with a dial indicator attached to a section of Miter Track.


Ken,

I knew when I posted this I was inviting questions but I was tired and hoped the "think about it" would save me some effort. Shoulda known better... :lazy2:

So let's think about it together: Miter gauges are used to hold a workpiece at a given angle and pass it through a cutter at that angle in a path parallel to the centerline of the cutter. That's why it's critically important to ensure your tablesaw blade is parallel to the miter slot, any deviation results in poor cuts or safety concerns. Less so for a bandsaw but wide blades can give you a problem. Just as critical if not more so for a disc sander, it'll throw your work back at you just as fast as a tablesaw if your gauge isn't traveling parallel to the disc.

But a router is different: there's no effective length to the cutter, it's essentially a single point of contact between the cutter and the work. That's why you can use a simple board for a fence, clamp one end and swing the other to get your desired depth of cut. Essentially there is no parallel to a rotating router bit, just a tangent intersecting its' circle of rotation.

While you could use a router table with a miter gauge to make square or angled cuts on the end of the work, that's almost always done by the tablesaw, radial arm saw or miter saw. Routers just aren't very efficient at cutoff functions, almost all shops have saws for this. Common practice is to dimension the work and then bring it to the router for further treatment, a rabbet, groove or profile for example.

Since the work is already square or cut at the desired angle, it's a simple matter to butt it to the fence and slide it through the cutter producing a cut parallel to the end of the work. For small work it's easy enough to cut a backer board at the same angle wide enough to ensure stability, hold the work against it and pass it through the cutter.

I'm sure I'm not telling you anything you don't know but there may be others reading this thread that don't have your experience, my apologies for the wordiness.

You have a good point with the box-joint jig, I've always done box joints on the tablesaw with a dado stack. The only fence I've used on the router table besides the clamped board is my current Incra TS/LS/Wonderfence setup, it makes box joints easy but I have to move the fence for each cut. Setting up a split fence for jointing as you described is easy enough but could just as easily be accomplished with a good straightedge and a feeler gauge. If you make your own featherboards you can make them long enough to clamp to the edge of the table.



Ken Bee said:


> Please explain to me how they weaken the table considering both are rigid sections of aluminum extrusion. If anything they would help maintain the rigidity of the table top in my view.
> 
> Just my thoughts on this often approached subject matter.


Now to the nitty-gritty.... This is gonna get a bit technical, bear with me.

I took a look at your uploads, you have a pretty typical tabletop: 2 pieces of MDF laminated top, bottom and sides with plastic laminate. Pretty much just like mine except I used BB ply. Google "MDF Manual", scroll down to pages 10-11 and start reading if you want reference material.

MDF is not of consistent density throughout its thickness, the outer faces are significantly denser than the center. It's pressed under heat so the end result ia a panel that's flat and pretty much stays that way under reasonable environmental conditions. It's a balanced system, strongest sections on the faces, weakest in the center.

Now think about what happens to that balance when you cut a groove in one side. You release tension in that side and it expands. The other side stays constant, one side expands, now you have a bow in what was previously a pretty flat surface. And to compound the problem you've sealed off all surface area with laminate except where you cut the groove. Those bare areas are now open to absorb moisture from the atmosphere and swell, getting larger. Larger on top, constant on bottom, now you have a hump.

While your track may add some strength in its length, that's totally dependent on the size of the attaching screws and their frequency. MDF is poor at screw retention so don't count on much help there. So the table crowns left-right at the groove but less so at the cutter. Now your cutter isn't square to the face of the work.

Front-to-back is another consideration, this effects depth of cut as well as squareness. So now your cut is not only out of square, it's no longer parallel to the face depending on where you apply pressure. If you cut the groove to an exact fit at low humidity, you've compounded the problem. The MDF absorbs moisture and swells, the aluminum track doesn't. The result is a bigger hump perpendicular to the cutter.

All of this movement may only be measured in a few thousandths of an inch and that may seem insignificant but the end result is inconsistency and unpredictability in the finished work that could take a significant amount of time and effort with scrapers, planes and sanders to correct. On the flip side, if the gods are with you and you hold your mouth just right everything could come out perfect. But that's a big if....

So there's the reasoning behind my brief response. You asked... 

HTH,
Bill


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## darsev (Feb 3, 2012)

Bill,

just two responses to your excellent post.

1. I have a cast iron router table extension to my scroll saw with t tracks cut into it. On one occasion only I have used the mitre track for series of parallel dado cuts - much easier than moving the fence. I am also considering using that technique for CD rack where the dado cuts are at an angle - say 20 degrees - to the face.

2. Re MDF absorbing moisture: this is a practical issue we face daily in the factory. Technically we need to edge band MDF within 3-4 hours of it being cut, or the edge flares from absorbing the moisture. I put up a post on one of the more severe issues we've had with this: http://www.routerforums.com/tools-woodworking/34222-wasnt-me.html The flaring from absorbing humidity was bad enough that the laminate itself was being gouged when trimming the edge tape. 

Darryl


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