Tune-Up & Repairs to the Dewalt
The blade clamps would put a slight bend to the blade after numerous holes on fretwork that made it difficult to feed the blade through 1/32" holes. I found out now that the allen screw and thumb screw that hold the blade have burrs on them that need to be filed off. Take both screws out of the blade clamp assemblies, top and bottom, and file them smooth. After doing that the blade doesn't bend anymore when doing a lot of fretwork. As the saw get used more the blade clamps have a tendency to build up and not work properly. Take the thumbscrew clamp out of the saw and make sure the end is clean and pivots freely. Do not try placing oil on the pivot. Some have had problems over tightening the blade clamps and stripping the threads out or breaking the clamp. Most of the time this goes back to the fact that the fact that the clamps had a build up of oil and dirt that let the blade slip. About all of the blades we buy have a very fine oil on them, and this builds up on the clamps. So they just tightened the clamp harder. If they had just cleaned the clamp when the blade started slipping, the extra pressure put on the clamp wouldn't have been needed.
I did have some problems getting it to cut a tight "v " pattern like grass, but in talking to others who now own them, that may have been an alignment problem with the blade causing it. So one of the first things to check on the saw is the blade alignment. If the blade is off side to side you can make it run true by adjustments. Check the blade for side alignment by setting a ruler against the side of the blade, while the arm is in the full down stroke. Then hold the ruler in place and raise the arm to the top of the up stroke. The blade should not have had any side movement to it. If it did then use the allen screws on the left side of the blade clamp to move the blade over in the blade holder until it is aligned. By moving the top and bottom screw the blade can be centered into the table slot. I have aligned the blade in my saw now and it made a world of difference in the way the saw performed. So check the alignment out before you even try the saw.
Some have had a problem with the switch not working. The solution that one person found was too use a spray can of electrical contact cleaner to blow into the switch. It makes me wonder it the spray blew the dust out of it, holding the contacts open, or if it was the actual contacts in the switch that were in need of cleaning. When I have the switch problem I'll try using the air compressor to blow the switch dust out first.
Stopping the knock on the Dewalt: I too experienced this knocking noise when I turned my speed above 5. There is an easy fix for this problem, and should only take you 10 to 15 minutes to accomplish. The problem is the tensioning rod is slapping the upper arm housing. Take your manual with the exploded drawing of the upper arm and table and follow these instructions. Loosen and remove the on/off switch assembly (four Torx bolts). this will give you access to the cam that adjusts the tension #26. With an allen key remove bolt #52 and cam #26. Remove four Torx holding the head assembly #44. This will give you access to the tensioning rod #24. It needs to be adjusted, but to do so you need to move the head assembly out from the arm. this will then drop down allowing free access to the tensioning rod. The tensioning rod screws into a fitting #23 buried deep inside the saw arm. to remove the knocking noise you need to adjust the tensioning rod #24 counter clockwise (lengthens the assembly). Try one full turn, re-assemble and see if it solves the problem. If not repeat this procedure in one full turn increments until the knocking goes away. It only took one full turn to solve my knocking problem. My saw now works like a charm, and it was a quick and easy free fix. I hope this helps.
For a parts breakdown on the Dewalt go here:
Butch ( Taken from a post on Sloan's discussion board )
An article by Bill Young on tuneup: Setting Up a Scrollsaw For Stack Sawing
There is no big secret to stack sawing. I use a DeWalt saw and have been ridiculed for saying that I stack saw most of my work, by people with saws three times the price of mine. That is what prompted me to make the simple setup required available to anyone it might help. First off, you need really good blades, so use a high quality blade of your choice. Next, make sure your blade is tensioned really tight. I donít use the push sideways or the plucking for a certain sound method at all. I just crank it up tight and Iím ready to go. The main problem most people have when stack sawing is either the blade is giving a cupping pattern from the top to bottom or the top is narrow and the bottom is wide or vise versa which makes it very difficult to remove the waste wood when fret sawing. Also on fine work, the top can be perfectly sawn only to find later that the bottom piece can be off far enough as to be not usable. Cupping is generally caused by a bad habit of pushing sideways on the blade as well as not enough tension. Push straight in on the blade without forcing it sideways and let the blade to the cutting. For some it is helpful to place the stool (or standing position) a little to the right of the blade because the cut always goes to the left due to the manufacturing process of most blades. This way makes it easier to push straight into the blade. Now the important part. Youíve heard it saidÖ..the saw is set up from the factory and requires no adjustment. That, for the most part is wrong. If you are cutting a single piece of wood and the blade is not exactly 90 degrees to the table, itís not much of a problem because the waste wood will easily slide out of the top or bottom. That is typical of a factory set saw. Now, with the saw still set up the same, try stack sawing 1/8Ē Baltic birch six deep on delicate fretwork. You have a nightmare on your hands. You canít get the waste wood out and the top and bottom pieces are a different size. Hereís how to correct it. First off, if your saw is a DeWalt, lay a ruler (or something thin and flat) on the saw table and up against the Side of the table. Now, at the end of the motor shaft, there is a slot where you can insert a screwdriver and turn the motor over by hand to raise and lower the blade. If the blade touches the ruler at one end and not the other, loosen the thumb screw on the right side of the blade holder and then the screw in the left side with an allen key whichever way it takes to make the blade track straight throughout the stroke. If your saw is not a DeWalt, then look for another way of making this lateral adjustment. It is a good point to keep in mind when upgrading to a better saw. Upgrading doesnít necessarily mean going up in price. Some of the$1,000.00 and plus saws donít have this feature so going way down in price to DeWalt could also be considered an upgrade. The saw blade has to be EXACTLY 90 degrees to the table. Get a small square and put it on the table and up to either side of the blade. Yah, I know, you havenít got a square that small. Well one of those little plastic ones out of a school kids protractor set will do. Now loosen the big knob under the front of the table and adjust the blade and table to match the square and tighten the knob. That was easy.. now weíre all set up right?ÖÖWrong. Those little squares are not accurate enough. That was just to get it close. But weíre not playing horseshoes here so close doesnít count. Now weíre ready for some fine tuning. Get some waste wood thatís between 1-1&1/2 ď thick. With a tight blade, start the saw and run a piece of wood in and twist and turn in every direction and then exit close to where you entered. The waste wood should easily slide in or out from top or bottom. But it wonít. This tells you that the blade is not yet properly set. Now is when you get a chance to test your patience. You need to loosen the knob and adjust the table ever so slightly to left or right because at this point weíre not really sure which way it should be. Tighten and run a piece in as before. Itís either going to come out in the opposite direction which means youíve gone a little too far so a little fine tuning back just a little will put it right on. When you have it set that the waste will easily slide in or out from either the top or the bottom, you have achieved perfect 90 degree alignment. Make sure that the adjustment knob is real tight now. After all that, you donít want it to get bumped out of alignment. Iíve had people say.. what about when I want to tilt the table for some angle cutting. Do I have to go through this again if I go back to straight cutting? The answer is yes but after a few tries at it, it does get quicker and easier and if you want to do accurate, easy, trouble free stack sawing, this is the only way regardless of the make or price range of the saw. I have a cardboard box sitting to the right of my stool and all my waste wood cuts are simply tapped on the edge of the box and the pieces just slide out. And thatís the way it is with a perfectly set saw. Hope this has helped anyone that is serious enough to take the time to do the job right. Work safely.
Subject: Re: Dewalt knocking
Posted By: Marvin, email@example.com
I had the same problem with my Dewalt.
I couldn't use the fix from the website listed above because I don't have an "exploded" diagram with part numbers shown. I called Dewalt and they mailed me a fix that simply involved removing the plastic cover on the switch, and the tensioning lever underneath. This gives you access to the cover on the tensioning rod. You remove the bushing from the rod. Push the rod back about 1/2", remove the screws, lift the front and it slides off. On the underside of the cover you can see light marks where the top arm hits the bottom of the cover. You can simply sand down the rounded underside of the cover where the marks are. Worked dandy on my saw. The Dewalt number is 1-800-4dewalt.
Posted By Warren on the WOOD discussion group.
Subject: Re: 788 tune-up
Posted By: warren59,
All DeWalt saws have the play in the blade holders. I don't know why, it just is and its not a problem. When the saw is running the holders will center themselves. I don't like Rick's way of squaring the blade with the table, its not the way to do it. Do it this way, Position your thumb screw and set screw on
the top and bottom so that a blade sets in the center of the blade holders. Put a blade in the saw, turn it on and run it, turn it off. Check that the blade is square with the table if its not do this. Look at your exploded parts view at the bottom half of the saw. Locate #46 the knob for tilting the table. Now look for #44 the
screw that holds on the zero detent assembly. Loosen that screw #44 and the whole assembly (table and all) will move enough for you to square the blade up with the table. When square, tighten the screw #44. Doing it this way, your blade is in the center of the holders and your zero detent is set at zero.
Wobbly tension knob
I found out how to fix the loose wobbly tension knob on the dewalt
saw this weekend. Just take out the 4 star screws on the plastic
housing for the on off switch on and you'll find a large allen screw
on top of the tension knob. Just tighten that down hard and replace
the cover and the 4 screws. Just passit along for someone who is
having problems with a loose wobbly tension knob like I was.
Teflon coated top
Article sent to me by Ron Brown 1/15/2006
(770) 682-9394 Office
(770) 312-9087 Cell
More pictures of the above article.
There is a minor problem with the newest crop of DW788 Scroll Saws. The spread between the blade holders has lengthened slightly due to a manufacturing problem with the wedge. The result is difficulty inserting the blade into the blade holders because there is only about 1/8" above and below the holders.
Just wanted you to be in the loop so here is a cc of the most recent email.
Ronald G. Brown [mailto:firstname.lastname@example.org]
Sent: Thursday, February 16, 2006 1:33 PM
Subject: RE: DeWalt Scroll Saw Help #2
Spoke with Larry today. He is not a direct line manager, but rather a 1-800 phone specialist. He has had conversations with the engineers and discovered that the DeWalt Plant Engineers believe the current crop of wedges were cut out of spec. The engineer actually had one machined to the correct spec and sent it over to the plant in Taiwan. Has no idea when the systemic problem will be solved.
Meanwhile, I guess the fix is to machine the wedge down some to achieve the 4-1/8" on center for the blade holders. I would not be afraid to do that in my own shop, but I can not recommend that you do it.
An alternative might be to ask Larry to have an engineering drawing/diagram of the wedge emailed to you and you could take it to a machine shop for the rework.
Good Luck and keep me posted.
Sent: Wednesday, February 15, 2006 9:20 PM
Subject: DeWalt Scroll Saw Help #2
Just a follow-up note on our conversation yesterday w/re to the distance between the saw arms that only allow a five inch blade to fit into the blade screw-holders spaced 4 3/4" apart (1/8" protrusions at each end of thumb-screw clamps).
Larry Wagner, DeWalt Product Manager (1.800.433.9258) called me today to discuss my situation of having received three new #788 saws all with the same problem over the last three months which have had to be replaced under factory warranty.
He told me that he had been receiving other complaints recently about this situation as well. And, that he agreed that the top and bottom blade protrusions should be about 1/4" above and below the aluminum cast blade holder and not just the threaded thumb-screw clamp hole.
So there you have it. Three 'Type 1' saws (a fellow sawer friend of mine, yours and Mr. Wagners') that DO NOT exhibit this problem and, three, 'Type 2' machines that I have received from DeWalt since November that do have this problem. At this point I am compelled to believe that ALL 'Type 2' saws have this type of a problem.
It would be interesting for you to discuss this matter at your monthly scroll saw club meeting this weekend to gather a consensus of other DeWalt #788 scroll saw users w/re to this situation. Please ask them to call Larry Wagner to voice their concerns and complaints if they too are experiencing this particular problem.
Thank you again for your help.
If I understand your situation, you cannot get sufficient tension on the blade with the tension lever. I have attached an exploded view of the scroll saw for your reference.
Three items to check:
1) Tension Rod Adjustment. Referring to #24 (Rod, Draw), it threads into the Wedge #23. Typically, it needs one or two more turns (clockwise) to enable sufficient tension with the tension lever.
In order to get to the rod (it is pretty easy, just takes a couple of minutes) Take off the plastic cover (#71) by taking out the 4 screws (#44). Just loosen the whole assembly and move it
out of the way. Remove part #26 and part #80. You will see the tension rod and a small bearing sleeve on the "L" end of the tension rod. Set the sleeve aside. The rod is flexible enough to turn
it without removing anything else. I suggest one CLOCKWISE turn, partially reassemble, test the tension and take up another turn only if necessary. I set mine to get proper tension at a 3
to 3-1/2 setting on the tension lever gage.
2) Item #57. There is a pivot bolt which connects the upper arm to the main housing assembly. If it is too tight to allow free up and down movement of the arm, you will have difficulty installing the blades correctly. Loosen it just enough so the arm won't stay up by itself and comes down freely - not slowly.
3) Then, when you install a blade, or go from hole to hole after making a cut, gently squeeze the two arms together as you tighten the blade holder. That way you are removing any play before
engaging the tension lever. If the arm stays slightly raised, you are having to use the tension lever to get back to zero before ever tensioning the blade.
I hope this solves your problem. Beginning with proper and sufficient blade tension with #2/0 blades will make all the difference in the world. 2/0 blades are tiny and typically don't last very
long anyway. I cut lots of 3/4" material with #7 and almost never break a blade before it is so dull that I need to change it anyway. Pretty much the same with #5's. Let me know how it goes.
From: Leo Davids [mailto:email@example.com]
Sent: Sunday, March 12, 2006 9:16 PM
Subject: DeWalt 788
Hello Rick I have been reading about the problems related to the New DeWalt Saws manufactured in Taiwan. I just bought a new saw and had the same problem with the blade chucks being to far apart. I resolved the problem by loosening the tension bar about two to three turns there by allowing the top arm to go a little lower. I phoned the DeWalt service center and told them about the problem. They were quite surprised to hear about it but they told me to go ahead and try that fix, rather than bringing it in to them. The fix worked.
Table hole problem
Now when it was time to secure the cast iron top to the TRUNNION and but before tightening the two screws that fasten the top to the trunnion I clamped a blade on set the tension and immediately noticed that the blade is too far to the right of the table tear drop holeÖ and to my amazement I could not adjust it! I attached two pictures to this email hoping it will help understand my problem. The table to trunnion screw holes do NOT allow left/right adjustments, only has up/down table adjustments so I am in a fit as to how can I align the blade to the table tear drop hole with out having the blade rub against the right side of the tear drop opening. I suspect the table screw holes or the tear drop hole is out of alignment and there is no hope for me to get the blade in the middle of the tear drop hole.
Brian D. Sorcic
Another problem that has came up on knocking
From: Dan Seymour [mailto:firstname.lastname@example.org]
Sent: Friday, April 27, 2007 11:33 PM
Subject: Have you seen this problem
I have a problem with my scroll saw and I was wondering if you had heard about this. My scroll saw (Dewalt DW788) started knocking pretty bad. I found a solution on your web site for the same description, but it didn't fix my problem. Since it was out of warranty, I decided to take a chance and open it to see if I could find the problem. What I found was that the "Con Rod Assembly" (the link between the motor and the rocker arm) was coming apart. The link was coming off of the bearing. The only reason it wasn't completely off, was that it was still attached to the rocker arm and actually cut into to rocker arm. I knocked it back in place and that fixed it, but it eventually works itself back off and I have to take it apart again. Sorry, it's a little long but I just wanted to know if you have heard of this problem.
Finally the real fix for the knocking!!!!
All the problem is in the front end.
Once you have the saw down to this point you are ready to start the fix.
Here is the part that needs the work. See the black spot center left, that is the knock point!
The fix is removing some material from the bottom. I used a file but sandpaper would work as well too.
Side to Side Fix
Another problem that can cause a knocking
Submitted to me by am email:
Front to back blade movement fix; DW 788 blade forward travel
( Taken from a thread on the SSWS forum; DW 788 blade forward travel)
Redbeard (Alan) and Ocelot (Ray Morgan):
What I find how ever, is that the blade moves forward a good 1/16 inch from top of the stroke to the bottom. This seems very aggressive, and makes it very difficult to turn the wood to make tight curves, since it’s moving forward and back a lot more than the width of the kerf.
Anyway, after getting no answers from Dewalt or anyone else on a fix, I took matters into my own hands and corrected it myself. The saw is wonderful now.
Here is the problem - The length of the top arm is longer than the length of the bottom arm. Or at least the mounting holes are off. (of course it could be opposite on yours) What I did to test this was remove the 4 torx screws that hold the bottom silver blade holder pivot assembly to the yellow frame. I moved the entire assembly out away from the yellow frame nearly 1/8" and temporarily clamped it in place. I ran the saw slow and the blade travel was nearly PERFECT! WooHoo!.
To make the fix permanent I had to use a dremel with a cutting wheel to make the 4 holes in the yellow frame into slots. Basically, I cut the metal so the holes were slots to the end of the piece. This allowed forward adjustment of the silver blade assembly.
The saw is wonderful now.
More from Ocelot (Ray Morgan):
Hmmm, It's been a while and I was trying several things from scratch, but I can think of two things. If I recall correctly, It needs to be done without a blade and you may need to give the motor a half turn or so with a flat head screw driver. There is an opening on the back of the motor and the motor shaft is slotted.
I don't think the assembly moved easily though. I know to tighten down the screws after slotting the holes, I used a flat screw driver between the yellow frame and the assembly to hold it out. It may not be necessary, but I think I also had to adjust the tension rod under the switch housing a turn or so to give it enough play to move the lower assembly. I was trying to figure it out as I went along from scratch, and trial and error, so it's hard to give a step by step instruction.
IMPORTANT - The assembly must be straight for the final clamp down - Meaning that the gap you create between the yellow frame and the silver assembly must be equal on both sides to keep the blade straight.
Also, I wouldn't make any permanent modifications or slot the holes until you test it first. If you can get the blade assembly moved out even a 16'th of an inch, and put something in there to hold it temporarily, you can put a blade in with just enough tension to take up the slack and test it. You can test it by putting a metal ruler or something behind the blade and turning the motor by hand to see the difference.
had a request from Rick for a picture of what I moved to achieve near zero forward blade travel.
It's a bit blurry since my good camera is hiding from me and I had to use an old cheapy. It should give an idea on how much I moved it. You can see the new gap between the lower blade assembly and the yellow frame. just over 1/16"
More from redbeard (Alan):
There was actually quite a bit of yellow paint compound in the holes of the two lower arm panels which I filed out, then slotted the two smaller front holes each side holding the lower blade assembly, as Ray showed.
I though maybe just removing all the paint might give enough slack in both the front and rear to help, but is wasn't quite enough. So I did slot out the front holes about 1/32 " with a needle file.
I reassembled with the arms as far forward as possible at the rear, and lower assembly as forward as possible. This is much easier in the down position. You can use a flat blade screw driver to rotate the motor from the hold in its middle.
All told, I moved the bottom assembly forward about 3/32" .
Before: in the up position the blade was furthest back but still sloped backward. In the down position it moved about 2/32" forward.
Now: in both up and down positions the blade is in the same place, with a slight swing forward of 1/32" at the middle of the swing down.
Before I couldn't make right angle turns at all without chopping up a big hole. I was wondering how on earth you guys did fancy fret work with such a machine. Now it makes clean jigsaw-like cuts!
FYI, I just used a rachet screwdriver with Torx bits T25 and T27, a small spanner and some needle files. The 2 front screws are slightly smaller than the base ones.
Just to complete this, here are a couple of pics of my adjustment. You can see the gap where I pulled the lower assembly forward.
More from Steve S.:
Couple hours in the shop and some success, but another twist to the alignment tail to add. I followed the advise and slotted the mounting holes of the lower panels. Any adjustment of the lower blade assembly outward made the problem worse in a more severe way. One of the keys to finding a root cause is figuring out what causes a reaction related to the problem. So, I moved the bottom blade holder as far back as possible and moved the top blade holder 1/64" or so forward to the limits of the existing mounting hole. That made a huge difference. It is not yet perfect, but the performance is greatly improved. Although I was content with the saw it now has less vibration over the entire range of the speed settings. Next day or so I am going to decide if making a slot in the upper panels is easier or removing metal from the forward edge of the lower panels is easier. I already know how to get the lower ones off.
Holding the arm up
Yes you can get the arm to stay up by tightening the pivot screw for the top arm. It was never recomended because it will cause wear on the pivot area, but if yours did stay up before it must have been tight. The biggest reason not to also was that you had to be sure to push the arm down all the way before attaching the blade.
A video of how to do this
Another problem that may be causing the knock