Dewalt rod knocking.

[Dave Monk]

I have a Dewalt that is about six months old. I work it about six hours a day.  Every once in a while it sounds like a rod knocking in the lower part of the saw. It will do it for a few seconds and then quit. Has anyone had experience with any noise like this. dave

[Lucky2]

Dave, I don't own a Dewalt, but I think you should check the linkage from one end to the other.

Len

[jerry1939]

I have a Delta, which appears to have the same working mechanism. The last 2 days I had "something" similar to what you described. Slowing down the blade speed helped. Today it suddenly stopped working. A bolt had sheared off. Bought a bolt at the hardware store and have about 20 minutes to finish reassembling tomorrow. To see the bolt, go to;

 

http://www.toolpartsdirect.com/dewalt-dw788-type-1-heavy-duty-20-quot-variable-speed-scroll-saw.html

 

On the bottom right, keep hitting the plus sign to enlarge the picture. It was bolt number 27, on the right side of the connecting rod.

 

Delta has a better picture;

 

http://www.deltamachinery.com/downloads/manuals/scroll_saws/40-694/40-694%20Scroll%20Saw%20Parts%20List%20Rev%203.pdf

 

Part number 34. Metric M5 X M35 long.

 

jerry

[CharleyL]

That bolt has a lot of stress on it. I have broken it too, so I  now keep a spare. Check the bearing and sleeve for wear while you are there too. Pull the sleeve out and add a tiny amount of synthetic grease to the needle bearings inside the bearing hole, then reinstall the sleeve and rotate it several times before installing the new bolt. You will be amazed at the difference that this little bit of additional effort makes.

 

Many of the bearings in these saws don't rotate more than 60 deg. They only rotate through a part of a revolution, in a repeating back and forth movement and the grease in them gradually migrates away from where the pressures are being applied, so these areas can dry up and wear more heavily than the rest of the bearing. A bearing that rotates a full 360 deg does not have this problem as the grease is pushed ahead of the needles all the way around, so it self lubricates. A little additional grease and rotating the bearing sleeve through several full revolutions will redistribute and mix in the new grease in as well as placing new very little used needle bearings in the positions receiving the higher workload.

 

Dave, this may be your problem, but check all of the bearings and rocking pivot points in your saw, because any one of them can cause a knocking sound when they begin to fail. 

 

Charley

Edited July 16, 2016 by CharleyL

[jerry1939]

Dave, I will echo CharlieL. The stupid design puts the entire load on just that undersized bolt.

 

In retrospect, I think that my bolt split in the middle quite some time ago. Got it back together & running this morning. Was pleasantly surprised to find that it now runs quieter.

 

In order to install the bolt, you need to remove the crankshaft from the motor & pull it toward you to get room to hold the nut.

 

THE MOTOR SHAFT HAS A LEFT HAND THREAD !!!!!!!!!!!! The motor has a square counterbalance on it. Grip that securely with a snap on wrench to hold the motor from turning. The nut is on darn tight, BUT REMEMBER THAT IT IS A LEFT HAND THREAD.

 

Apparently my saw ran quite a while with the bolt split in the middle, but I didn't know it. Eventually it ejected the half on the motor side.

 

jerry

[Dave Monk]

Thanks for your help guys.Being this saw is supposed to have a year warranty do you think I should work on it myself? I hate to part with it for a month by sending it to a service center.  dave

[amazingkevin]

I have a Dewalt that is about six months old. I work it about six hours a day.  Every once in a while it sounds like a rod knocking in the lower part of the saw. It will do it for a few seconds and then quit. Has anyone had experience with any noise like this. dave

My first dw788 did this too I used "lock tite" on the nut and it stopped it to this day 6 years latter for my friend i gave it too!

[hotshot]

Thanks for your help guys.Being this saw is supposed to have a year warranty do you think I should work on it myself? I hate to part with it for a month by sending it to a service center.  dave

 

Dave, if you can easily reproduce the symptoms for the Dewalt Tech, then definitely take it in.  If they can't get it resolved, I would start pushing for a replacement.  A well functioning Dewalt should be smooth and quiet.

[jerry1939]

Dave, Only you can decide which route to take.  When it comes to mechanical repairs, everyone is either (good)(fair) or (all thumbs.)  This appears to be your first incident with the saw.  There will be more over the years and you will be faced with something again.  If you choose to go the warranty route, check the freight both ways.  I'm 76 years old and trust myself more than someone with a certificate on the wall that reads, "Factory Trained Technician."   A lot of them couldn't make change for a dime.  If you tackle it yourself, watch this video:  https://www.youtube.com/watch?v=i7EWpq3aQeU   A lot of it is a waste of your time.  On a piece of paper, write the time in the video that pertains to you, so that you have starting points to review before starting the repair, THOUROULY CLEAN YOUR WORK AREA!!  Use the attitude that the smallest, most critical piece will start orbiting the earth.  Build a "wall" around the saw to catch dropped pieces.  (lumber scraps)(rolled up carpets)(wife's dresses).  You will drop something.  Below the saw table, remove the bolt from the arm that drives the lower assembly.  Prop up the back of the lower arm and the front of the saw body.  Remove 2 bolts and pull the 2 apart.  Split the saw body. Take a picture if you like.  IF you find a broken bolt, measure the diameter, decide the length and go to your largest hardware store.  (The first store I went to didn't stock anything that long.)  IF there is a broken bolt on the rocker arm, you will need to take the crankshaft off of the motor to replace a bolt.  The nut on the motor shaft is left-hand thread & darn tight!!!

 

However, I have great respect for people that recognize their limitations.  If you don't want to be without a saw for who knows how long, someone on this site once made the comment, "A scroll saw is like a roll of toilet paper.  Always keep an extra one under the sink,"  Here is a spare I would recommend;   http://www.farmandfleet.com/products/897887-skil-scroll-saw.html?feedsource=3&gclid=CNfO54Ti-80CFQmRaQodllQEyg

I had a Performax (no longer made) that I bought new for $69 at Menards that was identical to this.  Have posted pictures of a couple of things I made with a $69 saw.  Do NOT let anyone convince you that you Need bells and whistles.

 

Good luck Friend.

 

jerry

[Jim Finn]

My first dw788 did this too I used "lock tite" on the nut and it stopped it to this day 6 years latter for my friend i gave it too!

I had to put Loctite on this nut also.  I did that and then sold the darn thing and bought a Hegner.  That was many years ago.  Hegner still plugging along.