Delta 40-690 blade alignment

[jscott2]

I just bought the 40-690 and was surprised to find the blade tilted forward about 2 degrees.  The blade also moved forwards/backwards almost 1/8" as it moved up and down.

The local Dewalt/Delta repair shop had no idea how to fix it.  Dewalt support was unable to suggest a solution but with a little pushing I reached an engineer.  He suggested tipping the lower rocker mount forward by loosening the two supporting bolts and letting it tilt forward.  (The lower rocker mount is item #13 on the 40-690 parts list.)

There was just enough slack in the holes to make the blade vertical throughout its travel.  As a bonus, the forwards and backwards movement has been reduced to under 1/16".

As the 40-690 is identical to the Dewalt 788, this may also apply to that saw.

[Gabby]

I can only say that my 40-540 see saws about the same, which is why it's good to hold at corners so it will even out the cut. I don't know of any adjustment for that. Perhaps someone can clear that up for all of us.
Gabby

[tux_linux]

fine tip!

@ Gabby
Hold a piece of scrap wood right in front of the blade - you'll notice the shift movement.
If you saw into the scrap, turn off the saw and flip the scrap you should be able to push the scrap wood into the blade -> angle is set correct and if you can see no gap between blade and cut your blade is also perfect vertical.

[Gabby]

Torsten your tip is for a level table, and it's right on.
However I believe what jscott2 is talking about is the slight forward and backward motion of the top and bottom of the blade that I called see sawing, kind of like the motion of a teeter totter school yard playground ride. I don't know what they would be called in Germany.
Looks like this maybe    ------A-------    one end goes up and the other goes down.
Gabby

[tux_linux]

Well, it might need some pictures to explain it..

[Gabby]

As the arms move up and down first the top of the blade moves a bit forward  on the down stroke then the bottom movs forward on the up stroke as the alignment does not move together vertically straight up and down there is always a bit of rocking action. It is not side to side but frward and back just a small bit and when to the end of the cut where you want a straight cut it requires a pause to let the top and bottom of the blade catch up to each other depending on how much force is being applied to the cutting edge of the blade and how much it being bowed due to that pressure
I hope this helps,
Gabby

[jscott2]

Gabby,

What I solved by tilting the rocker mount was the forward tilt of the blade when observed from the side of the saw.  The top of the blade was tilted forward about 2 degrees, relative to the table, before the adjustment and is now as vertical as I can measure with my school protractor.

The forward/backwards movement of the blade was measured at the table surface by putting a ruler across (side to side) the table, against the back of the blade, and moving the blade by turning the motor with a screw-driver.  Can't recall if the blade was most forward at the top or bottom of the stroke but it was easy to measure the movement at the table surface.

Adjusting the bottom rocker mount also reduced this forward/backwards movement and the blade is also vertical to the table.  I want to test the blade verticality (is there such a word?) by cutting a complex shape out of 3/4" material to see if the cut-out comes out through the top and bottom but haven't had a chance to get into the shop for a while.

I hope this clarifies my original post.
Jim

[Gabby]

Jim I don't know if my saw is adjustable vertically as you describe I'll have to find out. Can you describe where the rocker mounts are on the saw so I know I'm on the same page with you?
I can actually see the fore and aft travel of the blade especially at a low speed setting.
I have noticed this disappears once I'm feeding the wood straight into the blade and have pressure against the blade. So I've come to utilizing that motion as a indicator of if I'm straight.

I just went out and checked with a straight edge behind the blade, and the movement of the blade is on the down stroke, slightly forward at the top and the bottom pulls away, then the reverse on the up stroke. I don't try to turn the motor I just push the top arm down or lift it up by hand. I doubt it makes any difference. I doubt I'll try to adjust the movement out as it is probably only 1 or 2/32" and not a problem.
Gabby

[jscott2]

Gabby,

The lower rocker mount is item #13 on the 40-690 parts list.  Go to http://servicenet.deltaportercable.com/Products/Detail?productNumber=40-690. To see where it fits into the saw, download the "Exploded Art - Default" PDF diagram.

Easing off the two bolts #44 and two #126 (at F and F') allowed #13 to tilt forward, around the lower bolt, just enough to make the blade vertical.  I didn't have to elongate the holes in #6 and #81 as some have done for the DW788s.

Hope this helps.  Let me know how it turns out.
Jim

[Gabby]

I don't think my older machine is built the same, I'll have to go to my manual and see if there is any adjustment. I'm not about to screw with it if it isn' broken. LOL
Gabby

[marmoh]

Sure like the look of the 690 over the 540.  If I could find a different bottom blade mount I'd change it in a heart beat. I get to use all of my accumulated "words" every time I change a blade.

[dgman]

I can't imagine you using words like that Marion.

[Gabby]

Good Ol' Country Girls know quite a few things, right Marion?
G

[marmoh]

Sorry to bust your bubble Dan, but sometimes I've used words that I didn't even know I knew ...
Gabby, being a "country Girl", I've learned that sometimes when you step in it you just have to clean your shoes and keep on going .. 

[Russ C]

You all crack me up. From blade alignment, to country girls, to foul words. Oh my