Dewalt 788 Noise Problem

[OCtoolguy]

Well, I'd go back to basics. Make sure the saw is bolted down SOLID. Then get a stethoscope type of device. I used to sell an automotive type for about $10. Bring the saw up to speed where noise is most prominent and try to locate the area of noise. As for what you have done so far, when I did mine I had to grind quite a bit off the bottom of the cover. If that is still the problem there should be a mark where the drive link is hitting the cover. Try taking the cover off and coloring the underside with felt marker similar. Make sure that is not still the problem. Keep at it. You'll get it.

[rick_b]

Thanks Ray - I do have a stethoscope but that didn't seem to help.  I'll try getting it clamped downand using it again.  How far back did you remove material on the underside of the cover?

Rick

[OCtoolguy]

22 minutes ago, rick_b said:

Thanks Ray - I do have a stethoscope but that didn't seem to help.  I'll try getting it clamped downand using it again.  How far back did you remove material on the underside of the cover?

Rick

I took enough material off that it moved the "arch" back and gone in about the first 3/8-1/2 inch. Quite a bit.

[Roberta Moreton]

Different approach. 

 

[rick_b]

Well I stepped away from this saw again.  Once it got cold outside I had no more excuses  .   This saw  has two problems - noise and a motor speed control that  seems to cause the speed to surge and/or slow down a bit as the speed control is increased.  I've decided to focus on the noise issue - assuming the speed problem is unrelated to noise.  Following are the steps I have followed so far:

1.  Secured to saw to the benchtop - a VERY slight improvement to noise level but not enough to even consider victory.  Noise presented as slight at lower speed setting of 1, increases with a knocking sound at 2 and 3, knocking reduced but still noisy at 4, knocking worse at 5 and knocking much less but still noisy at 6 through 8.

2.  Applied a layout bluing to top and bottom of tension rod cover and retested.  No indication of damage to the bluing which would indicate that something was contacting the cover.

3. Checked all upper and lower arm and chuck connection fasteners and retested - no change to noise levels

4.  Adjusted tension rod one full turn CW - Noise/knocking seemed better but still unacceptable

5.  Adjusted tension rod a second full turn CW - knocking significantly worse at speed 2 and above

6.  Adjusted tension rod a third full turn CW - significant knocking at higher speeds - 5 and above

7.  Adjusted tension rod 4 full turns CCW (3 back to starti g point +1) - Serious knocking goes away but still very noisy at various speed

8.  Adjust tension rod 1 full turn CW - back to initial start point

So now I'm lost - can't really tell where the noise is coming from even with a stethoscope.  The next step is to remove the left side covers and test the machine to see if that helps identify the noise source.  I don't have a lot of hope for success but/I am open to any suggestions.

In addition to the  noise I believe there is something wacky with the speed control causing the surge/speed variation but that's a problem for another day.

And oh yeah - I stripped a threaded hole in the upper rocker mounting casting 0 least of the issues at this point.

Rick

[OCtoolguy]

Have faith Rick. You are doing all the right things, eliminating possible causes as you go. At this point it's probably going to be a loose or broken bolt in the drive mechanism. When I tore mine apart I found a non-stock bolt (screw) that somebody had installed before I bought the saw. It also helped quiet mine down. 

[rick_b]

Unfortunately I have been side tracked by a bedroom update and haven't had a chance to try anything with this machine for awhile.  I will be getting back to it soon I hope and will post an update.

Rick