Introduction: Router Jig: Wood Jar Lid Covers AND Coasters

This is a simple jig to allow you to use your router to make wood covers for jar lids, regardless of the size of the factory lids.

Alternately, you can use it to make cup and glass coasters with indentations to stop the cup or glass from slipping off the coaster. You could add cork to the bottom, if you wished.

Previously, I just used double back tape and a piece of plywood with a hole sized for the lid I was making. The double back tape stuck a blank to the guide. You, then, routered a hole in the wood using a router template bit, which uses a bearing to follow the template hole [in the plywood] to make a hole the same size in the wood blanks.

This jig still uses a piece of plywood with a hole in it cut to the exact same dimension needed to drop a given lid into, or sized for your coaster. Instead of tape or hot glue, it uses a second piece of plywood. The base and the template work together as a clamp to hold the work piece for routering the hole in your work piece.

Clamping is accomplished via two simple clamps that are nothing more than two bolts permanently mounted in the plywood base, and two T-nuts mounted in homemade knobs, two commercially available, female jig knobs, wing nuts or even standard bolts to apply pressure against the upper, plywood template, causing it to squeeze a work piece between them.

The lower piece of plywood, the base, into which two bolts are mounted, is used for all the different templates (pint, quart, gallon, plastic, metal, Mason or Ball and coasters) you choose to make. The upper piece of plywood, the actual template, can be swapped for one with the size hole you'll need for a given jar lid or your coaster projects.

The top pieces, the templates, have two through holes that match the bolt holes on the base, so they can be lifted on to and off the base to create different sizes of lid covers. To reduce drag, when swapping template guides, the holes for the bolts are significantly oversized. For example, if using 1/4-20 bolts, the through holes in the templates are drilled to 3/8".

Both the base and top guide plate need to be big enough to allow your router to move around on the jig and to clear the whole area of the lid hole without running into the jig knobs. I was using a trim router (Bosch Colt), so was able to make my jig much smaller than I would have to if was using, for example, my 1-3/4 horse router.

Too, if you will be making one gallon lid covers, both the base and template will need to be significantly larger than for a quart jar.

One of the most important features of this jig is, it is a "what you see is what you" affair. That means, if you draw holes on your work piece sized for the jar lid cover you are going to make, when you slide it into the jig, it should align, perfectly, with the template.

To be a "what you see is what you get" jig, not only do you have to size each template hole to near the size needed to drop the lid in, you ALSO MUST use pattern/flush trim bits to cut the hole in the work piece. These are common bits and have the bearing on the top.

The bearing MUST be the same size as the hole the bit will cut, which is common for these kinds of bits.

The bearing will follow the template pattern you made. The bearing is held in place by a collet that fits tightly on the shaft of the router bit and is held in place by a set screw (usually an Allen screw). This allows you to replace the bearing from time to time.


(1) Enough 3/4" plywood (AC, CDX or what have you) to make a base and templates sized for the jar lids or coasters you are going to make. If you were making a jig to produce lid covers for pint and quart jars, that would be three pieces. One for each lid and one for the base. If making coasters, one for the base and one for the coasters.

If using a trim router, the pieces of plywood should only need to be about 12" square, unless you were making gallon jar lid covers. Of course, if using a router with a bigger base, you would want to increase the size for that. If you think you may be making different coasters and lid covers using different routers, and if you can afford the storage space, think about increasing the size to around fourteen to sixteen inches square.

(2) Two 1/4-20 bolts 4-1/2" long.

(3) Two 1/4-20 T-nuts [if you are going to make your own jig knobs].

(4) A couple pieces of scrap plywood or wood to make jig knobs [again, if you are going to make your own knobs].

(5) If you are not going to make your own knobs, you can just buy 1/4-20 butterfly nuts or regular jig knobs. Of course, you could just use a 1/4-20 nut and washer for each knob, if you don't mind using a wrench for each install and removal of the template.

Step 1: Tools & Equipment Needed or Helpful for the Build

To build this project, you'll need:

(1) Measuring and layout tools are necessary to determine template and base sizes, and to set up the hole sizes for the lid covers. A compass and ruler is a must. Things like calipers would be handy, but are not a must (unless you're looking for an excuse to add an important tool to your collection).

(2) Something to cut the plywood and your lid covers or coasters to size. This can be a table, band, skill or jig saw. A bandsaw would make cutting down to the walls of the finished lid a much quicker project, but the same can be done with a coping saw.

(3) A drill, to drill the holes for the 1/4-20 bolts, for mounting the bolts into the base, and for making the T-nut jig knobs.

(4) A 1/4-20 bit. This is needed to drill through the base for the clamp bolts. For this, tight is a good thing, even if you had to thread the bolt into place.

(5) A spade, Forstner or spur bit to sink the bolt head [flush] in the base. If the bolt head measures 1/2" it may be a 7/16" would be ideal, so the bolt head fits tight enough it does not spin when the clamp is being used to apply pressure to the work piece.

(6) A 3/4" spade, Forstner or spur bit bit to drill the hole in the plywood knob for the T-nut.

(7) A jig saw to cut the hole in the lid templates.

(8) One or more sander to finish the lids. A drum-disk is ideal for bringing the rough lid covers down to the chosen diameter or shape. A belt sander could be used in place of a drum-disk sander. Of course, a standard pad sander could be used in place of either. It would just take longer. However, the pad sander is VERY helpful, for the final sanding too. To detail out the hole size of the template, a dowel with sandpaper wrapped around it can be used to remove wood to the line drawn with a compass.

(9) The obvious - a router. I used a Bosch Colt detail sander, since the project was not taxing on the motor. However, if I were doing several lids, I might switch to my Porter Cable 690 or similar router.

(10) Pattern/Flush cut router bit(s). Having a couple of different cutting lengths may be a good plan.

If the bit you use is too short (e.g., 3/8" cutter length), your router may not be able to move down enough to cut a hole to the depth you need to finish the lid.

If the bit cutter length is too long (e.g., 3/4"), the router may not be able to move up enough AND still keep the bearing riding on the template (destroying your template). A 1/2" cutting length may be the Goldylocks bit (just right). Especially if your router has enough movement to allow you to avoid trying to take too much material off in one pass.

If you must take a deep cut, move slow and in circular motions taking only a bit off at a time, to avoid burning a good bit.

(11) If you have a bandsaw, you can make a circle cutting jig to pump out lids VERY quickly. In the time it would take me to freehand cut, then sand one lid or coaster blank, I could pump out ten or more. To see how to make this simple jig, and to use it, just run a search for "bandsaw circle cutting" jig.

Step 2: Building the Simple Jig

(1) Cut pieces of 3/4" plywood (AC, CDX or whatever you have) to at least 12" x 12" or larger, depending on the router you are using and the size of the lid you are making.

Cut as many pieces as you will need for templates

For example, if the base of your router is nine inches across, the bit is at the center, 4-1/2" from the edge. If you were to draw a circle sized for your lid cover, you'd want about five inches from the edge of the hole to allow the base to go all around it.

If you were doing a pint jar lid, twelve by twelve inches of base might be sufficient to avoid running into the clamp bolts. On the other hand, if doing a gallon jar lid, you would have to add a few inches.

Based on the foregoing, and if you have the room to store the jig and sufficient materials, making the base, say, 16" by 16" would allow you to use any router and to do gallon jars with room to spare.

If room to and materials are limited, measure and adjust accordingly.

(2) Mark center of each template to locate the center of the hole you'll be cutting for the lid cover. Simply running lines from corner to opposite corner will give you center.

(3) Measure the jar lid for which you want to make a template. Calipers will give you what you need, or you can just lay the lid on a ruler, with one edge on the end of the ruler, then move the lid around for the maximum reading.

(4) Divide the dimension you got in step three in half and set your compass for that reading.

(5) Draw a circle around the center point of the X.

(6) Drill a starter hole inside the circle you just drew, then cut to the line of the circle using a jig, scroll or coping saw. Stay just inside the line, since it's easier to make the circle as close to perfect as possible using sand paper than it is using a saw.

(7) Using a spindle sander, a dowel wrapped in 80 grit or whatever method works best for you, sand the wood to bring the hole to the line drawn with the compass.

(8) Using a ruler or tape, mark in 1/2" from both sides of each corner. Using a nail, an awl or what have you, make a starter hole for drilling the guide holes.

NOTE: This step presumes all the templates and the base are the same dimension. If they are not, the holes will not align using this method. Instead, you will have to lay the base on top each template and use the clamp holes of the template to mark the drill point of each template.

(9) Drill a hole the depth of the bolt head into the base using a spade, Forstner or spur bit. You can mark the depth using tape.

(10) Drill on through the base holes just drilled using a 1/4" bit, and using the center hole left by the spur, spade or Forstner bit as a guide.

(11) For each template, switch to a 3/8" or 7/16" bit and drill the marked holes. Again, the larger hole allows the templates to slide over the base clamp bolts with relative ease.

(11) Slide the 1/4-20 bolt in through the bottom of the base, so that when pulled into place, it will be (approximately) flush with the bottom. You can use the clamp knob or bolt to pull the bolt into place.

NOTE: If your bolt head holes do not hold the bolt head with sufficient pressure to stop it from spinning, when clamping a piece, you can run a small screw on a flat side to obstruct movement. Hot glue or epoxy would solve the problem too.

(12) If you chose to make your own clamp knobs, do a quick Instructables search for "jig knobs" or "T-nut knobs" and several members offer steps on making them. If you went with commercial knobs, butterfly nuts or just 1/4-20 nuts, you are, now, ready to make lid covers.

(13) To make future use of the jig easier, I write on them the lid for which they will be used. Too, I mark the compass settings used to mark the holes on the face of the jig (see photo).

Step 3: Using the Jig to Make Jar Lid Covers

(1) Cut blanks for your lids from your chosen wood. They, of course, need to be cut down in both thickness and diameter, or width and length sufficient to allow it to fit in the jig.

I cut my stock to a bit over 5/8" thick, even 3/4" thick, which leaves plenty of room to sand the top and bottom of the cover.

You can cut the outer diameter before routering, or after. I recommend cutting afterward, because you may take off more than planned and there is no going back. Too, if the wood has a tendency to be brittle (e.g. will chip or break up when being routered), that problem is less likely to result in a destroyed project if you cut and sand to diameter after the piece is routered.

I make my walls about 1/8" thick, when completely sanded. However, you can make the walls much thicker, if that is your preference. Doing so would allow you to add more round-over on the edges, whether because that appeals to your tastes or you just want a better grip.

A lot of the cherry wood I used tended to blow out during the routering process. To reduce this, I saturated the brittle areas of the sides with either polyurethane or thin cyanoacrylate ("Super") glue.

Especially if using cyanoacrylate glue, insure you have plenty of ventilation. Not only might the process toss off visible smoke, it's nasty smelling and cannot be, in any way, good for your lungs.

If you chose to saturate the wood with polyurethane, some wood will suck it up like sponge. Just keep adding until it won't take anymore, or you run out of patience. Then, give the poly a couple days to harden, before finishing the project.

(c) It may help, if you're cutting brittle wood, to rough cut the blanks you'll be routering in at least a 1/2" oversized, then cut the outer diameter or other shape (e.g., square or diamond) after you routered the blank.

(d) If you do get a blow out, there is NO reason you cannot clean the blown out area up and glue in a replacement piece, the go back to the router stage again. This could even be done on purpose to add details to the lid cover.

(3) To aid in aligning the work piece in the jig, layout the circle you are going to router on the piece of wood you are using, before installing it in the jig. Do this by setting your compass up on the set up marks you added to the jig face for the lid size you are using.

(4) Slide the work piece into the jig, align the drawn hole on it with the template. Then clamp the work piece in place by tightening the two clamping knobs.

(5) Router the jar lid cover in steps, to avoid bogging the router, burning and dulling the bit, and destroying the blank.

Install a pattern bit in the router - THE BEARING MUST be sticking out below the router base, so it comes in contact with the jig, or you will both ruin your jig and, possibly, the blank (depending on how much oversized you cut it).

Again, you do not want to try to take off too much wood with any one pass. About 1/4" of the bit should be sticking out below the jig guide. For each set up, after you've secured the bit (remember, it doesn't take a lot of pressure to secure the bit), if the bit is resting on the work piece (blank), the router base should be about 1/4" off the jig.

(6) With the router bit well away from the edge of the guide, not touching the work piece, and with the router base resting on the jig, turn on the router and, slowly, tip the router into the work piece, holding it with both hands. Once the base is flat on the jig, start moving the router in small, circular motions to remove a bit of wood at a time. If you have to push hard, you're pushing too hard. The router should glide fairly easy (with a sharp bit).

If you keep the router working off the edge of the guide nearest you, it will cause the router to throw the debris away from you. When an area is clean and you're ready to move, you can turn the jig, so the router continues to throw debris away from you.

To inspect your work, just lift the router straight up [from about the center of the hole] and shut it off. If you see something you missed, turn the router on and tip it in again and touch up that area.

(6) When done, lift the router straight up with that cut, drop the bit down another quarter inch and repeat the steps above. Repeat this until you've cut a hole deep enough for the metal lid to drop into.

(7) You can determine how deep you are going into the lid by, WITH THE ROUTER OFF, standing the jig on edge, holding the base on the jig, like you would if you were routering the lid, but with the bit on the outside edge of the jig. You will be able to see, at a glance, how much wood is left before you would blow through the blank.

(8) If your lid fits tight and stops at the bead, you can hand sand a slight bevel around the inside edge to let the bead seat into the lid cover.

(9) When you've completed the router work, and if you did not already cut the exterior to size, do so now. A bandsaw and drum or belt sander are ideal for this. The bandsaw gets it close and the sander makes it easy to bring the edge to a drawn line (circle).

(10) Finish sanding. 150 grit should be enough, if you are applying poly, shellac or lacquer.

(11) Use hot glue, epoxy or even double back tape to secure the lid in the cover.

(12) You're done - use your new Rolls Royce jar lid cover.


IF you see anything I need to clarify or change, or if there is something that would help you build this, please feel free to let me know and I'll do my best to polish this up for you.

As it is, there seems to be a lot of information here, which might suggest the whole project is complicated. It's not. I just tried to touch on the details to save you some of the learning curve I suffered getting to this point. The whole thing could be summed up as:

(1) Cut as many pieces of plywood as different sized lids you'll be making covers for, then one more for the base;

(2) Make the base and the template plywood all the same sizes, which allows enough room to cut a center hole the size of the lid cover, and to move the router around the hole without coming in contact with the corners (where the clamps are).

(3) Drill the center holes for the templates using jar lids as your guide.

(4) Drill holes in the corners of the base and templates so they all line up, when stacked.

(5) Run two bolts through the base corner holes and slide one of the templates over it.

(6) Cut a bunch of blanks from your choice of wood. Make them about 11/16" thick, or a bit more.

(7) Draw a circle on the blank the same size as the template hole.

(8) Slip the blank in and align it.

(9) Run jig knobs, butterfly nuts or regular nuts down the bolts until the template is clamping the blank to the base.

(10) Router a hole, a little bit at a time.

(11) Remove the finished blank.

(12) Cut it to the desired shape, leaving at least a 1/8" wall, or more if the tooth marks you'll sand out are rough.

(13) Sand as needed.

(14) Apply a finish.

(15) Use hot glue, double back tape or epoxy to secure a lid in the cover.