DeWalt 788 and alignment issues

[geener]

Hello, fellow scroll sawyers! I have a Dewalt 788 with blade arm alignment issues. I saw where someone else had encountered the same problem, but never posted a possible solution.

The link to the other thread is here: Alignment Question - Scroll Saw Woodworking & Crafts Message Board

On thinner woods, it doesn't cause a problem, but on woods thicker than 1/2", there are issues. I cut puzzles from 1/2" and thicker wood, the top of the blade enters the wood before the bottom of the blade does - this results in puzzle pieces that can only be connected one way - since the back of the puzzle is out of alignment with the front of the puzzle.

The arms are square from the front (they don't lean left or right), but they are off square from the side (they lean front/back). This is not something that can be adjusted by blade placement within the clamps, because the arms themselves are off.

Has anyone else encountered this and if so did DeWalt offer a solution? I'm passed warranty - when I first encountered the problem, I put it down to my "newbyness" - but have discovered that in this case it wasn't operator error.

Any input would be appreciated.

[Marsha]

I don't think there's anything wrong with your saw. You must make sure the blade is absolutely square to the table top. To do this, find yourself a metal L, tension the blade as far as you can and then set the L on the table against the side of the blade, the blade should run right down the side of the L with no gaps. If there is a gap top or bottom, then you need to adjust the table until the gap is gone. To adjust the table, loosen the level gauge knob under the table and move the table until there is no gap between the L and the blade, then tighten the knob.
I hope this makes sense, it is what I found to be wrong with my saw, when I had cut a puzzle and could only get the pieces in one way.
Marsha

[geener]

Hi, Marsha! Thanks for the response.

I did use a square and made sure the blade was properly aligned.

When viewing the blade from the front, I have a perfect 90 degree angle going.

When viewing the blade from the side, I have a 1/4" difference between the top of the blade clamp arm and the bottom clamp arm.

The problem is that while the table can be tilted left and right, it cannot be tilted forward and back to compensate for what must be a manufacturing issue on the disparate length of the clamp arms.

So, it's not a left/right issue, it's a top/bottom issue - and I don't think that has an adjustment available. At least not one that I can find. I have emailed DeWalt since I posted the earlier message. I'm afraid that I'm going to find myself out of luck. Although I've only used the saw over the past couple of years, I got it as a Christmas present a couple of years before that, so I'm sure the warranty is long gone. sigh.

Thanks for taking the time to respond.

[lucky788scroller]

The only thing I can offer is to check where the table is bolted to the piece that has the angle markings on. There should be NO washers or shims between the table and that part. I suppose its possible too that the hole in the back end of your saw table was machined in the wrong location (the hole to high will raise the front of the table), but I've never heard of anyone with that problem. When you are measuring the amount the blade is farther out on the top compared to the bottom, is that with the saw all the way in the upstroke position? If you move the blade to the bottom of the downstroke, does that amount its off change much? It should change a little bit because of the saw design, but not 1/4 inch! Sorry I cant think of any other possibilities for you. Oh, and welcome aboard geener! Dale

[popsshop]

Geener - Yepper, might have to rebolt your table.

had a similar problem and ended up boring a new hole through the case to move the back end of the table just to get the blade square 360 degrees around the blade. Worked like a charm.

The way I heard it, the 788 is manufactured for an agressive cut. Squaring the blade 360 give you a not-so-agressive cut.

fred

[bobledoux]

Clean out the blade slots. Make certain the top and bottom blade clamps allow the blade to fully back in before the clamps are tightened.

[CanadianScroller]

I was just looking at the manual and exploded diagrams from ServiceNet, the dewalt and Delta site http://www.dewaltservicenet.com/ServiceNet/logon.asp
I cant see any adjustment for the front to back offset but like the others have said remounting the table may correct the problem.
You may also be able to slip a washer behind the trunnion that would tilt the table backwards slightly.
There maybe some more help on that site, I havent checked into it too deeply.

[Powakee]

I've had nearly the same exact issue as you describe and I notice it primarily on puzzles over 1/4 in. thick. On mine, the 0 degree detent notch is not right at 0 degrees. I have to constantly monitor it to keep the thing square. But, now that you say it may be a front and back issue I'm gonna check that side too.

Popshop, I wonder if you might either take some pics or describe in more detail how you fixed your saw. I'd appreciate the knowledge just by itself.

John

[Neal Moore]

Geener....Check the adjustment knob that allows the table to tilt. There should be a bushing that fits around the bolt and rides in the slot of the trunnion. If the bushing is missing or or not riding in the slot it will cause the table to be out of alignment front to back. The "type 2" Dewalts have had a couple issues with table flatness and distance between the upper and lower arms but this is the first I've heard about the problem you describe. You cannot rebore the rear "pin" hole for the table because it fits into a "saddle" mounted on the lower arm case and there is no room for another hole. The DeWalt is not a true verticle cut saw which means that there will always be a difference in depth of cut from the top of the wood to the bottom. The thicker the wood the greater the difference. I just checked my 788 and using 1 inch wood, the blade cut approx 1/64 inch deeper on the top than the bottom. Generally, providing your table is square side to side with the blade, the problem you describe is caused by putting too much side pressure on the blade when cutting in a turn.

[greg194799]

Geener

The front to back saw blade alignment is the way the DeWalt 788 is designed. Sorry to say but that is the only flaw with that saw.
I would read Patrick Spielman’s book “The New Scroll Saw Handbook” it will describe the different makes of scroll saws and how their cutting movements work.
I’m not a puzzle maker so I don’t know if this would work for you. Try using a thicker blade to cut your puzzle. It would have a wider saw cut and the pieces would be loser fitting.