Intro: Make a Riving Knife for the DW745 Tablesaw
I have a DeWalt DW745 tablesaw.... but I have the first generation. It comes with:
- a plastic blade guard that covers the blade... and gets foggy, twists, and can be easily pushed into the path of the saw
- Two anti-kickback pawls, which grab onto a workpiece if it starts to move towards the user.... but also leave scratches on both sides of the cut
- A riving knife.... that protrudes above the top of the blade, so can't be used for cuts that are less than the full depth of the material.
The current model DW745 riving knife / guard solves all these problems, however I don't want to buy a new saw.... the one I have still works just fine.
So: Time to make a riving knife
- A Riving knife from the new DW745 (Ordered from DeWalt, $35 ish)
- Black Spray paint (metal)
- Shims (3 shims come with the DW745)
- Masking Tape
- Vise (optional but helps a lot)
- Caliper (optional but also helps a lot)
- Belt or orbital sander, or sanding block, or metal file
- 120 grit sandpaper
I think this took me around 3 hours, excluding paint dry time.
NOTE: This instructable includes instructions to modify part of your tablesaw. This may void the warranty. If you have any doubts about doing this, buy a new saw that has a riving knife that does what you want. I assume to liability for any damages, injury or loss whatsoever as a result of this instructable.
Step 1: Remove the Existing Knife
Remove the blade insert and crank the blade all the way up.
Mark the guard just below the top of the blade, about 1/8" down. This mark will be used to position the top of the new guard.
On the right side of the blade & just behind it, there is a star knob. Loosen this and pull the assembly out of the holder.
There are two small springs holding the anti-kickback pawls down onto the workpiece. To make it easier to work with, I pulled the springs out from the pawls.
At the bottom of the holder there are two 'legs'. This is the part that has to be re-created on the new riving knife.
Step 2: Trace the Outline
Put some masking tape onto the new knife over the two 'legs. Most of these legs will be cut off.
Lay the new knife on top of the old.
Align the top edge of the new knife with the mark you made in the prior step, indicating where the top should be.
Align the curved parts - the parts closest to the blade.
Trace the outline onto the masking tape.
Step 3: Cut
I didn't use masking tape - I used a regular pencil to mark onto the metal directly. However, this mark got wiped off during cutting, and was hard to see.
I used a normal hacksaw and cutting fluid, I wouldn't bother with the cutting fluid next time as it just made the tape come off.
What did make it easier was holding the knife, with a rag, in a vise during cutting.
Step 4: Right Shape, But Too Thick
So the new knife is a bit thicker than the old. This means you have to sand it - very carefully. A caliper will help a lot during this step, but if you don't have one, you can just keep checking fit of the new riving knife in the tablesaw itself.
I sanded the metal off using a benchtop belt sander, and it only took 15-20 seconds to get it to the right thickness. It is also important that you sand evenly on both sides.
Next time I think I would try hand sanding or use a metal file: If you sand too far, there is no easy way to go back.
After sanding, I painted it with black anti-rust paint.
Step 5: Shim Into Alignment
This tablesaw comes with s few thin metal shims, in case the blade guard is out of alignment. The instruction manual describes how to install the shims. I had to use one of these to get the new knife into alignment.
Basically - you want the knife to be directly in line with the blade. You may not need to shim, it all depends on how accurate your sanding was.
Once shimming is complete - tighten down the star knob, replace the yellow insert, and lower the blade.
Double check to make certain that the top of the riving knife is below the top of the blade.
Do a test cut - Stay off to the side, use a push stick, and use as much protective gear as you have - just to make certain that the knife functions as intended.