DW 788 problem - Scroll Saw Woodworking & Crafts Message Board

sdguy · 09-18-2009, 12:40 AM

Last week my 1.5 year old 788 stopped working. First it began knocking pretty badly, but within an hour of my first noticing the knock the motor stopped. It wasn't the switch--I could hear the motor trying to come on. I read about the knocking solution online, so I dismantled the switch cover and exposed the tension rod cover plate. It looked like there might be a little wear, so I sanded it a bit. I also blew compressed air into wherever I could and then reassembled, but this was not my problem. The motor still wouldn't come on.

At this point, I took the saw in to the local DeWalt service center. They admitted that they don't see too many scroll saws. They opened it up and found that it was full of saw dust, replaced the circuit board, motor, and cord.
They charged me a fraction of what he would have ordinarily charged because the saw is still fairly new.

I got it home and foolishly bolted it back to the workbench before really trying it out. The motor works fine now, but the tension is way off. I can't get it anywhere near the tension it should have (at setting 5 the blade will still bend easily). I'm guessing that when they put it back together, they did something wrong with the tension rod at the other end.

Obviously, I can take the saw back to the center and make them fix it, but does this sound familiar to anyone? Is this an adjustment that I can make fairly easily? I really don't want to unbolt the thing and tote it back in there.

Any thoughts?

Sally · 09-18-2009, 01:32 AM

Recently after servicing, my tension was off too. So I took the saw back. They said it was fine and it is. Well - I now have to push down on the arm to push the blade a little tighter then tighten the tension. Does this make sense???? So now I attach the blade in the bottom, start to tighten the blade screw on the top, push down a little, tighten the top screw well, push down on the arm with the heel of my hand and pull the tension tight.
I think while they were servicing it, they just made everything tighter. (using the word tight too many times but I can't think of another word)
Hope this helps.

JohnB · 09-18-2009, 02:05 AM

My Dewalt also lost all tension and when the blade is not tight you get a knocking sound.
The tensioning rod screws into a cast crap metal bracket at the rear of the saw, and the thread in this had stripped.
When I get a minute or two to spare I'll put a helicoil in. This should solve the problem.

sdguy · 09-18-2009, 03:43 AM

Thanks, Sally. What you described makes sense, and I was able to get the blade to the correct tightness. Still kind of a drag to have to do it that way, but there it is.

lucky788scroller · 09-18-2009, 06:22 AM

Just for kicks, give this a try. Loosen up the screw nearest you on the main saw casting by the upper arm.Its the lower one of the three near the top.Just back that screw up about 1/2 turn, and see if that allows your arm to drop down a smidge lower. That may be the problem. I do put a little down pressure on my upper arm as I tighten the blade thumbscrew, but its because I dont have my easylift spring adjusted exactly right.

sdguy · 09-18-2009, 06:47 PM

Hey, that worked, too! Thanks!

09-18-2009, 12:40 AM	#1
sdguy Junior Member Join Date: Feb 2008 Location: San Diego Posts: 29	DW 788 problem Last week my 1.5 year old 788 stopped working. First it began knocking pretty badly, but within an hour of my first noticing the knock the motor stopped. It wasn't the switch--I could hear the motor trying to come on. I read about the knocking solution online, so I dismantled the switch cover and exposed the tension rod cover plate. It looked like there might be a little wear, so I sanded it a bit. I also blew compressed air into wherever I could and then reassembled, but this was not my problem. The motor still wouldn't come on. At this point, I took the saw in to the local DeWalt service center. They admitted that they don't see too many scroll saws. They opened it up and found that it was full of saw dust, replaced the circuit board, motor, and cord. They charged me a fraction of what he would have ordinarily charged because the saw is still fairly new. I got it home and foolishly bolted it back to the workbench before really trying it out. The motor works fine now, but the tension is way off. I can't get it anywhere near the tension it should have (at setting 5 the blade will still bend easily). I'm guessing that when they put it back together, they did something wrong with the tension rod at the other end. Obviously, I can take the saw back to the center and make them fix it, but does this sound familiar to anyone? Is this an adjustment that I can make fairly easily? I really don't want to unbolt the thing and tote it back in there. Any thoughts?

09-18-2009, 02:05 AM	#3
JohnB 1 Tin Soldier Rides Away Join Date: Sep 2007 Location: Kalgoorlie, Western Australia Posts: 5,161	My Dewalt also lost all tension and when the blade is not tight you get a knocking sound. The tensioning rod screws into a cast crap metal bracket at the rear of the saw, and the thread in this had stripped. When I get a minute or two to spare I'll put a helicoil in. This should solve the problem. __________________ Regards John "The Golden Mile" Clowns to the left of me, Jokers to the right, here I am, Stuck in the middle with you. Some of my Stuff Retired Medically Unfit WA Police Officers

09-18-2009, 06:22 AM	#5
lucky788scroller Senior Member Join Date: Sep 2005 Location: wisconsin Posts: 6,354	Just for kicks, give this a try. Loosen up the screw nearest you on the main saw casting by the upper arm.Its the lower one of the three near the top.Just back that screw up about 1/2 turn, and see if that allows your arm to drop down a smidge lower. That may be the problem. I do put a little down pressure on my upper arm as I tighten the blade thumbscrew, but its because I dont have my easylift spring adjusted exactly right. __________________ Dale w/ yella saws

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09-18-2009, 01:32 AM	#2
Sally Senior Member Join Date: Nov 2008 Location: Renton WA Posts: 1,596	Recently after servicing, my tension was off too. So I took the saw back. They said it was fine and it is. Well - I now have to push down on the arm to push the blade a little tighter then tighten the tension. Does this make sense???? So now I attach the blade in the bottom, start to tighten the blade screw on the top, push down a little, tighten the top screw well, push down on the arm with the heel of my hand and pull the tension tight. I think while they were servicing it, they just made everything tighter. (using the word tight too many times but I can't think of another word) Hope this helps.

09-18-2009, 03:43 AM	#4
sdguy Junior Member Join Date: Feb 2008 Location: San Diego Posts: 29	Thanks, Sally. What you described makes sense, and I was able to get the blade to the correct tightness. Still kind of a drag to have to do it that way, but there it is.

09-18-2009, 06:47 PM	#6
sdguy Junior Member Join Date: Feb 2008 Location: San Diego Posts: 29	Hey, that worked, too! Thanks!