1. MDF has been used in a number of recently built tracks, it produces a smoother surface and a smoother slot, it is better structurally. MDF is a little heavier, but perhaps thinner sheet can be used. The minimum thickness for the track surface is 12mm (1/2 inch), although if you are using chipboard, a greater thickness is an advantage.
2. I have a router table top with a laminate surface and a rubber edge band on the sides. I made it years ago on an MDF core. Now, I'd like to have a miter slot on it. How should I go about cutting that slot? Should I simply fire up the router with a mortising bit? I'm mostly concerned about cutting through the laminate top and rubber sides.

A melamine-coated MDF table will provide the smooth, sturdy surface you need. An aluminum or resin base plate is a must-have for any budget. Good to have features for a great-value router table. A resin router table is a step up from MDF for stability and strength. Choose a split router.

Learn how to make a simple router jig for cutting dado slots. This simple jig makes it easy to cut accurate dadoes with a router. This jig is easy to build and simple to use.

Tool: Triton Plunge Router

Transcript:

Chris Marshall: Hi folks, I’m Chris Marshall, with Woodworker’s Journal Magazine. One of the strongest ways to install shelves in a bookcase — like this one — or a cabinet project, is to fit the shelves into dadoes in the sides. But to do that, the dadoes need to be cut perfectly straight and to exactly the right width for your shelving material. (And when I built this bookcase, I also needed the shelf dadoes to stop right here. Those can be tough to cut accurately with a table saw and dado blade.

CM: So for stopped dadoes like that, I reach for a simple-to-make slotted dadoing jig for my router. Here’s the one I used for the bookcase project. It’s got a platform to support my router base, with a slot down the middle that fits a 1” outside-diameter rub collar mounted in my plunge router. The jig’s base rests against the edge of my bookcase or cabinet side panel, and it squares the long slot across the panel when I clamp it in place. And if you look here, there’s an even deeper slot cut into the base. That’s made by the actual router bit you’ll use with the jig. It will show you the exact position your router will cut the dado slot, so it’s a SUPER handy index to set this jig accurately.

CM: And once the jig is clamped in place, this slot makes sure that my router can’t drift off course when I’m routing my dadoes, because the rub collar can only go in one direction — straight. With this jig, you’ll always rout dadoes with confidence —whether you’re building a bookcase or another shelving project. And in this short video, I’ll show you how to build one of these jigs.

CM: Start by cutting two, 6-in.-wide platform pieces from 1/2”-thick MDF or plywood. I made mine 26” long, which will allow the jig to cut dadoes up to about 18”. But, you can make the platforms however long you need them to be for your projects. (Flipping jig over to show) As you already know, you’re going to need a base piece for the jig. Make it from 3/4” scrap, 3” wide and exactly 13” long. And you’ll also need this 13”-long bridge piece too, to secure the platform pieces at the end of the jig. I made my bridge 2-1/2” wide.

CM: Start assembling the jig by brad-nailing or screwing one of the platform pieces to the base piece, flush with its end. Attach the bridge piece in the same way to the other end of the platform, but this time, to its opposite face. Now we need to fit the jig to our router’s 1” outside diameter rub collar. This will be the dedicated size that you’ll always use with this jig. For the next step, grab a steel rule or a scrap that measures exactly 1” wide. I’m going to set the second platform piece into position here, and then set the rub collar between the platform pieces, over the base. Now, I’m going to slide my steel rule between the platform pieces on the other end, under the bridge. That establishes our 1” slot.

CM: Now clamp the second platform in place carefully, making sure that the slot doesn’t change. Then nail the parts together to secure the second platform. If you’ve built the jig carefully, the rub collar should slide in this slot without extra play. There’s just one last step to do before your slotted dadoing jig is ready for use. Install a bit in your router that you plan to use with this jig. I’ve got a 23/32”-diameter straight bit in mine. It cuts a dado that’s the perfect width for today’s undersized 3/4” plywood.

CM: Now install the rub collar and set the router for a 5/8”-deep pass. Rout a slot across the base of the jig on top. Put a piece of scrap wood in front of the base, underneath, to keep the bit from splintering when it exits this cut.

CM: And now you’ve got your indexing slot, so you know exactly how to line this jig up for cutting dadoes. That’s it! Oh, one last thing: it’s not a bad idea to write the bit size, and rub the collar size, right on the jig — so you’ll remember what to use with it, later. These slotted jigs (B-roll) are my FAVORITE way to rout dadoes. Quick, easy and accurate! I hope you like yours just as much as I do. And, if you liked the looks of the bookcase [B-roll] at the beginning of this video, you can find free, downloadable plans plus a video that will show you how to build it, by visiting woodworkersjournal.com. Thanks for watching.

Introduction

This article is part of our CNC Beginners Cookbook series.

Workholding is the generic term for any device or method used to firmly hold your workpiece while machining it. While CNC Routers are technically milling machines, and they share some similarities in workholding, they’re basically a whole new ballgame.

Spoilboard

A spoilboard is a disposable work surface mounted atop the router’s permanent table. The spoilboard is typically MDF and protects the router table from damage as well as being an expendable surface that can participate in workholding.

From time to time a spoilboard will need to be surfaced. That means using a spoilboard cutter to clean up any gouges or cuts and make the board flat and parallel to X and Y axis travel.

Screw into Spoilboard

This is a very common method and involves screwing into the spoilboard to hold the work. It’s cheap and cheerful, but it does leave holes in the workpiece and can be slow. For tasks like this, grab an electric impact driver, air ratchet or similar tool to help drive the screws faster (as well as removing them faster). Another disadvantage aside from it being slow to bolt things down is that hitting one of the screws with a cutter will often break the cutter. If it’s travelling at feeds and speeds intended for wood or other soft materials, it’s going way to fast when it unexpectedly hits hard metal.

Polymer Nails into Spoilboard

This interesting idea is courtesy of James Irmiger of TechShop SOMA and Instructables. The idea is to use polymer (plastic) nails to secure the workpiece to the spoilboard:

Using Polymer Nails to secure the workpiece to the spoilboard…

According to James, the process is a little bit fussy and requires adjustment of air pressure and can be sensitive to overly hard wood. But, when once it is dialed in, it works great. Removing the workpiece just requires a little tap with a mallet to break the nails–they’re strong at resisting pullout but shear off easily. With a nail gun, this technique can be a lot faster than screwing into the spoilboard.

Double Sided Tape and Glue Fixturing

Small parts that don’t expect high cutting forces can do well with double sided tape and various kinds of glue.

One popular method is to use painter’s tape and super glue.

Here’s what you do:

1. Scuff the pieces and clean as best you can. For metal, I clean with acetone, isopropyl alcohol, or brake cleaner.
2. Apply the painter’s tape. That’s the blue stuff painter’s use to mask parts.
3. Apply super glue to the tape.
4. Lay the part down carefully onto the tape. Try to make sure any air escapes.
5. Clamp it briefly or put a weight on it.

Your part should now be adhered to your bed and it will be held pretty solidly.

How do you get the parts loose?

Pry up with screwdriver, putty knife, or razor blade. You can also soak it in acetone, which will dissolve the superglue. Lastly, heat will break it loose. Be very careful with heat:

Danger: Super glue, or cyanoacrylite, releases toxic cyanide gas when heated!

You may need to sand or fly cut the superglue off in the worst case, but it usually doesn’t come to that.

Clamps and T-Slots/T-Track

On CNC Routers, T-Slots are typically created using T-Track, which are metal T-Slots designed to be attached to your MDF spoilboards.

Rockler T-Track bolted down to top of MDF with Clamps…

Rockler T-Track Intersection Kit in a recessed slot with a typical bolt used with the track. Rockler has a wide variety of parts and kits for T-Tracking…

There are a wide variety of different T-Track systems and accessories for them available if you search the web. T-Tracks can be very versatile, but like bolting through to the spoilboard, you must take care the router doesn’t hit a bolt or T-Track in the middle of the job.

Tab Supports: Workholding Via CAM Software

What if your CAM software could solve some major workholding problems for you, wouldn’t that be neat?

Turns out some CAM software can help out with workholding quite a lot by automatically creating tabs. Here’s a video of MeshCAM’s facility for creating tab supports to help machine a part that has to be machined on 2 sides and is awkward to hold otherwise:

Using MeshCAM to add tab supports so you can machine a part on 2 sides…

We offer MeshCAM at CNCCookbook because it’s one of the easiest to use CAM packages there is.

Vacuum Tables

Vacuum Tables are often the best solution for the flat sheet work often being done on CNC Routers. We’ve got an entire article dedicated to CNC Router Vacuum Tables, so click through to check it out: