Intro: How to Make an Adjustable Work (Cut/ Drill/ Saw) Stop
I made this because I was making repetitive cuts on my radial arm saw with multiple pieces similar lengths. This adjustable stop made it very easy to cut several pieces all the same length, reposition the stop at the next length and cut the next set of pieces and maintain uniformity.
This particular piece was made to fit the wood fence that was added to the table on the radial arm saw that I have, but this concept could be modified to work in any number of applications or with several tools. I will most likely make another (prettier one) for my drill press table as well, as it is very handy to position pieces uniformly each time without measuring every piece.
This is being done years after the project was complete, so pictures are limited.
Step 1: Materials
Here is what I used for this project:
- 1/4-20 thumb screw
- 1/4-20 flange nut
-1/4-20 tee nut
- 2 part epoxy
- misc screws/fasteners
- misc. scrap wood
-hand saw, band saw, radial arm saw, circular saw or the like
Step 2: Measuring
The first step is to determine what dimensions you will need your stop to be. Mine was over what is roughly a 2x2. You need a block of wood for the front, a second piece to go over the fence and be the back support, and two thinner pieces to ride on the front of the fence.
The stock I happened to use was leftover from the cabinet shop I worked in years ago, and it is maple 1.25" x 3.5". My front piece, just to give some example dimensions, is about 4.75" wide, and the front to back piece is between 3.5" and 3.75". The front piece is the one with the head of the thumb screw coming out of it.
You need to allow for the height of the fence or rail you are putting the stop on, and add enough height to run a couple of screws or other fasteners into the block that runs front to back.
Whatever you use where the plywood is shown here needs to be thick enough to stick out further than the tee nut and the flange nut.
Step 3: Machining the Front Block
The first step with the front block is to measure for a hole to put the thumb screw through. You will put hardware on the other side of the thumb screw to contact the rail and hold the stop in place.
First measure to the horizontal center of the block. In my example the front block is 4.75" wide, so I marked in the center of the 4.75" width.
The height of the rail your stop mounts to and the width of the head on the thumb screw determine your next measurement. Ideally you want your hardware to hit right in the middle of the rail so you get a good, square contact surface. If your rail is 2" tall, measure 1" up. If it is not that tall, make sure that your hole is high enough for the head of the thumb screw to spin in without hitting the table below. If it does, you either need to drill higher or modify your thumb screw to fit (make the head less wide), or use a different lever altogether.
You need to drill a hole all the way through the block with a drill bit that is big enough to mount the tee nut in. The tee nut needs to be inserted on what will the back side of the front block.
Step 4: Machining the Rear Support Block
For the rear support block, you need to cut out a groove for your rail to pass through, essentially making an L shaped piece. If the groove is too deep front to back, it will not fight tightly on the rail, so you need to make sure that you measure your rail carefully. The other consideration here is to account for the thickness of the flange nut and the thickness of the lip of the tee nut that will still be proud of the front block once it is mounted in its hole.
So that works out to be: rail thickness+ flange nut height+ tee nut flange thickness+about an 1/8" or 1/4".
(The 1/8" or 1/4" depends on how close to the thickness of your tee nut and flange nut your plywood is)
Alternately, you may just use: plywood thickness+ rail thickness+ 1/8"
You can also see that the length your thumb screw needs to be depends on the thickness of the front block. You may have to countersink or counterbore the front block if the thumb screw will not work. Important: Make sure to dry fit the components before final assembly!!!
Note: The top piece of the L needs to be tall enough to have a couple of screws in it from the front block to assemble them.
I cut the groove in my block with multiple passes with my radial arm saw, but it you don't have one you could very carefully use a circular saw, router, band saw or a regular hand saw (I certainly don't recommend maple if you are using a hand saw!!!). You can be creative, just be safe!
Side note: my block was U-shaped, with one leg of the U much shorter than the other. The black outline shows the shape of the block, and if you choose to make yours similar in shape, the leg of the outline pointed to with the black arrow needs to be the same as or shorter than the thickness of the side support pointed out with the red arrow. If it is not, the stop will not have as much side to side support and really you won't need the side blocks.
Step 5: Machining the Side Supports
These are the blocks made of plywood in my project. Size them according to the size of your front block, minus the area in the middle for the rear support block to fit similarly to as shown.
Look at the arrow in the picture- I recommend you leave a groove at the bottom to help give a relief for dust- this way the stop will travel side to side more easily as you continue to cut and make more dust.
Step 6: Assembly
Once you have drilled your hole in the front block, and machined the groove in the rear support you can assemble the stop. The side support pieces can be machined after the front and rear blocks have been put together as long as you have taken into account the thickness of them properly.
Hammer the tee nut into what will be the back side of the front block.
Thread the thumb screw into the tee nut, putting the threaded end in through the front of the block so the thumb portion you turn is in the front of the block. Screw it all the way in and dry fit the flange nut on the end of it. The thumb screw needs to be able to make several revolutions starting with the tee nut against the block and tightening the screw so that it protrudes from the block several turns so that it can tighten against your rail. Once the dry fit is worked out, mix up your epoxy. The flange nut needs to be epoxied onto the threaded portion of the thumb screw with the flange facing the back. Let this dry and cure, making sure to not get epoxy onto the flange portion of the nut. The flange needs to remain free to turn so it won't mar the rail.
Line up the bottoms of the front block and the rear support block, with the front of the rear support block centered on the back of the front block. I used glue and screws to assemble mine, and I highly recommend drilling pilot holes for the screws that connect the two blocks together.
Attach the side support blocks, making sure that the their thickness is slightly thicker than the flange nut sticks out as you can see in the second picture. I attached my side supports with an air stapler, but you could glue and screw them in place instead.
You are ready to go- just place your stop over the rail, tighten it down and now you can make multiple, repetitive cuts quickly and accurately!
Step 7: Adj. Stop in Action
It took a few days but I have some pictures of the stop in use. This is not the saw table that I built the stop for, but it had a similarly sized fence. I hope this visual helps. Thanks to JLo for letting me dismantle his workstation for pictures. Maybe not dismantle, but still. : )