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The Proverbial "Knocking Noise" (DW-788, Type 1)


John Smith

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Having read all the DIY articles on addressing the knocking noise, I pretty much eliminated all that I could find and fix myself.

The question I have now is for the Tensioning Rod, Part# 24. From what I can see, this rod (or its parts) does not move when in use. There are no moving parts that come in contact with it while in use. So, how is adjusting this rod a potential solution to any knocking sounds ?? I have a very simple mind. I just can't figure out why some people say this "may be" one of the culprits. So, what am I missing here ?? (before I put it back together again for the 6th time).

 

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52 minutes ago, John Smith said:

Having read all the DIY articles on addressing the knocking noise, I pretty much eliminated all that I could find and fix myself.

The question I have now is for the Tensioning Rod, Part# 24. From what I can see, this rod (or its parts) does not move when in use. There are no moving parts that come in contact with it while in use. So, how is adjusting this rod a potential solution to any knocking sounds ?? I have a very simple mind. I just can't figure out why some people say this "may be" one of the culprits. So, what am I missing here ?? (before I put it back together again for the 6th time).

 

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You are very close to the problem but you haven't gotten to it yet. The problem is on the underside of that cover. It's not at the point that you have highlighted. I'm attaching a picture(s) of what needs to be done. Once this has been done, it keeps the upper piece that connects to the blade arms from hitting the underside of that cover. It's actually two separate problems but they can both make the same rattle sound. The tenshion rod also must be shorted by screwing it in, not out, of the wedge that it pulls on at the rear of the saw. That takes all the "slop" out of it so that it doesn't have the ability to flop around at high RPM.176000392_OperaSnapshot_2022-07-23_112950_www.scrollsaws_com.thumb.png.0e61c5fa5237847a99e3e37842dd118e.png

Edited by OCtoolguy
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The tension rod that connects to the tensioner arm is held very firmly in place by the cap. While I had it open, there was no slack or slop in the rod itself. I'm done. There is nothing else to do. For me, in my very limited experience, it is running perfect now. Very, very little to no vibration and the blade is perfectly aligned (for me) and I'm very satisfied with the machine as it is running now, all I have to do is put some projects through it and see how they turn out.

in http://www.scrollsaws.com/  Stopping the knock on the Dewalt: to remove the knocking noise you need to adjust the tensioning rod #24 counter clockwise (lengthens the assembly).Try one full turn. Then you say to turn in, not out (clockwise) . . . . well, since I didn't notice any movement in the rod while it was running wide open, I didn't do anything to it and buttoned it all up and it's done. Thanks for the input. Edit: The cheap Point-n-Shoot camera that I am using (not a smart phone) may be amplifying and distorting the sound which you hear in the video that sounds like it is coming apart. And actually, in person, it is running very smooth and I do not hear a knocking noise or other screaching sounds. (so it may be my recording device).

 

 

 

Edited by John Smith
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1 hour ago, John Smith said:

Ray - I shaved off the hump on the first time taking it apart. During my internet searches for problems, this was one of the common ones - so that's been done

Maybe not enough. I had to take enough off that it actually left that area "gone" for about 3/8" from the edge.

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13 minutes ago, John Smith said:

The tension rod that connects to the tensioner arm is held very firmly in place by the cap. While I had it open, there was no slack or slop in the rod itself. I'm done. There is nothing else to do. For me, in my very limited experience, it is running perfect now. Very, very little to no vibration and the blade is perfectly aligned (for me) and I'm very satisfied with the machine as it is running now, all I have to do is put some projects through it and see how they turn out.

in http://www.scrollsaws.com/  Stopping the knock on the Dewalt: to remove the knocking noise you need to adjust the tensioning rod #24 counter clockwise (lengthens the assembly).Try one full turn. Then you say to turn in, not out (clockwise) . . . . well, since I didn't notice any movement in the rod while it was running wide open, I didn't do anything to it and buttoned it all up and it's done. Thanks for the input. Edit: The cheap Point-n-Shoot camera that I am using (not a smart phone) may be amplifying and distorting the sound which you hear in the video that sounds like it is coming apart. And actually, in person, it is running very smooth and I do not hear a knocking noise or other screaching sounds. (so it may be my recording device).

 

 

 

I found, through experience, that if I lengthened the rod, it became sort of floppy loose and had a tendency to rattle. By shortening it and taking that slop out of it, the noise went away. Anyway, to your point, if it is running vibration free and quiet, best leave everything alone. I watched your first videos and it sounded like mine did when it was making that noise. That's the only reason I mentioned it. I'm happy if you are happy. Now, go make sawdust. Also, I'm sure that others will gain something from our back and forth's and your videos as it's a common problem. Most people don't have the know-how to take these things apart and fix what's wrong with them.

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Most people don't have the know-how to take these things apart and fix what's wrong with them.

yep - that's how I lucked out in this one - the seller didn't have the knowledge, ambition or time to mess with it. So he just "got rid of it". Hopefully, someone will stumble across the conversations and this excercise will get them to get up and running. Thanks again for tips.

John

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2 hours ago, John Smith said:

yep - that's how I lucked out in this one - the seller didn't have the knowledge, ambition or time to mess with it. So he just "got rid of it". Hopefully, someone will stumble across the conversations and this excercise will get them to get up and running. Thanks again for tips.

John

Yer welcome sir. 7-8 years ago, I was in the same boat with my first Dewalt so I had to go searching. That's when I found Scrollsaws.com. And then I found this group. Very thankful for both.

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