A rhythmical mechanical knock coming from your scroll saw mean there may be a problem with the tool. The scroll saw isn’t thudding or making a higher pitch whineing sound. It’s making a knocking sound from its heart at a time when all you are doing is cutting a simple curve.
That’s an unsettling sound from piece of equipment you are relying on to do delicate work, and it shakes your confidence in the saw. Something is either worn out or loose and the DeWalt scroll saw were meant to do fine work. When you hear that knocking sound, ignoring it will result in a dead motor or breaking a blade.
The armature’s shot? Crankshaft snapped? Most owners conclude it’s inside and dead.
But more likely they’re overlooking common maintenance mistakes. And you can take care of those problems with a screwdriver and a spare blade. Once you know where to look, that mystery become an easy repair.
No need for the saw to come back. Just open her up and have at it. The most common reason is lack of proper tension on blades.
Why Your DeWalt Scroll Saw Is Knocking
Lack of Proper Blade Tension
You want your scroll saw to have just enough tightness to allow the blade to travel true without flexing or rubbing against the guide rail. Loose blade tension cause the blade to tap on the guides as it move. That tapping sound is in sync with how fast the blade spin.
To end the tapping, many people crank down on their tension knob and break off the blade. Find the happy medium. The blade should feel like it has some give while still being firmly gripped by the tensioner.
Each time you replace your blade, take a second to check the tension. A blade that’s too loose will tap. A loose blade doesn’t last long before it destroys pivot point.
Worn or Misaligned Bearings
The next thing to look at is worn or misaligned bearings. Small ball bearings allows the blade to move around a pivot point. Over time they pick up dirt and wear away.
Without any lubrication, the metal will grind on the metal. The knock you hear is sharper than the sound of the blades wobbling. The bearings might just be dirty and need cleaning but if they aren’t, you might need to replace them.
Not all bearing last forever and DeWalt designed their parts to last a long time. With your hand, test how smoothly the blade move up and down. Does it feel gritty?
Time to replace the bearings and get it operating quietly again. But vibration can also be caused by an out-of-balance or defective armature. As the armature turns in the motor, the armature turn the blade back and forth.
Out of Balance or Defective Armature
An uneven commutator, or one that has shorted out on its windings will make the motor shudder. That shudder transmit into the frame and sounds like a knock. Diagnosing an unbalanced or damaged armature is more difficult at home.
It’s usually accompanied by other signs such as sparking or loss of power. If you think the armature might be the problem, turn off the saw right away. Continuing to run a bad motor can lead to total failure and should of been sent for professional repair.
Table Out of Square Alignment
Another thing that adds noise is having the table out of square with the blade. Your table should be square in line with the blade path. When the table are twisted, this causes the blade to bind on the material.
Binding causes resistance that the motor fight. Which will make the table pound rhythmically. Make sure the table bolts is tight and that the table is flat.
A warped table makes the blade have to work hard and messes up your cuts. It’s not difficult to adjust the table alignment. Just make sure the blade is absolutely vertical to the wood.
Loose Hardware Inspection
Last, inspect your saw for any loose hardware. Screws get loosened by vibration over time. The blade clamp, the motor mount or even the base plate gets a little loose.
A rattle occurs as a screw knocks around in its mount making a metallic sound. Walk around the saw with a screwdriver or allen wrench. Check all connections and tighten anything you see.
I know it is tedious but it’s the easiest thing to fix. Sometimes it is only a half turn of a stubborn screw. If you have a loud DeWalt scroll saw on your hands there are several things to consider.
First, it’s a matter of routine maintenance. Is the blade tightened correctly? Are the bearings lubricated and running well?
Work from the outside in. Usually when you’ve found the cause it will be quiet as a mouse and cutting like butter. Tune up your tools and they’ll repay you with accuracy.