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General Category => Tutorials, Techniques and Tips => Topic started by: jscott2 on August 03, 2011, 09:50:41 pm
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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.
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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
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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.
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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
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Well, it might need some pictures to explain it..
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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
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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
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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
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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 (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
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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
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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.
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I can't imagine you using words like that Marion. ::) :o
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Good Ol' Country Girls know quite a few things, right Marion?
G
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Sorry to bust your bubble Dan, but sometimes I've used words that I didn't even know I knew ... :o
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 .. ;D
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You all crack me up. From blade alignment, to country girls, to foul words. Oh my ::) ::) ::)
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Gabby,
The adjustment I made isn't in my manual, the idea came from the Delta service engineer. The saw has a 5 year warranty so I didn't want to start elongating holes, as some have done to solve the same problem on their DW788.
BTW, in an earlier post I wanted the blade vertical when I should have said perpendicular to the table.
Russ, this might bring the thread back from the "foul words" but perhaps not. That's one of the things I like about this forum, people are relaxed enough that drifting off topic is OK.
Jim
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Sorry about that. If I post again, I will keep it technical and on topic. Marion
( No foul words expressed or implied. )
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Marion, please believe me, I wasn't complaining in my last post. What happened in this thread is very much what happens when a group of friends get together. Sometimes the conversation departs from the original topic.
When I first found this forum, I noticed that it was a much more relaxed forum than some others and I feel very comfortable here.
Again, I was not upset about the later posts, I actually enjoyed the comments. Those comments might also be a sign that the "technical" discussion was pretty well complete.
Jim
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OK, Guess I just got my pants in a wad there for a second ;D
Figured that since you were below 1/16" and Gabby was at 1/32" and his went to the playground to teeter totter and rock, that the serious stuff was over with.
I would never want to offend anyone here by anything I might "say" ... I just have a peculiar sense of humor and feel everyone should laugh every day.
I would still love to find an alternative to my bottom blade mount as it usually makes me lose my cool when I change a blade. ( that's when the foul words come into play .. or the hubby ticks me off )
Glad you chose this site to be apart of ... I belong to 3 other ones but this is the only one I bother people at ;D ;D
Marion
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I've got to laugh, LOLOLOL
Looks like we're all still friends, that's what makes this forum so special (thanks again Steve).
Jim,
I haven't been feeling too chipper the last couple of days but wasn't going to say anything about it, so I coped out on the adjustment investigation on my machine. I knew what you were talking about vertical shmertical. LOL
I actually think the action of the blade slightly off perpendicular serves a purpose by making the majority of the cutting action on the down stroke. Let us know how it cuts after the adjustments.
Marion,
We all step in it from time to time, it's no big deal, that's what they make boot scrapers for. LOL
YTB you're the best!
Thanks Jim, glad we had this talk and got to know each other a little better. I hate stuffed shirts, and love down home people.
You'd never guess would you? ::)
Gabby
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Followup on the blade alignment.
I finally got a chance to test the adjustments to the saw. Took a 3/4" piece of pine and free-handed a circle about 1.5" across and tried my best to not side load the blade.
The "circle" dropped out the bottom as well as it fell into the top so I think the adjustments for blade perpendicularity are as good as they are going to be.
I'm a beginner so I ask you, is this a good test of the blade being perpendicular to the table from the front as well as from the side?
Now I have to learn to make sharp corners and to follow the line.
Jim
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Jim, If your circle falls out on both top and bottom, then all is well as far as I'm concerned.
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IF you can make a circle that drops thru top and bottom then my friend you are one darn good scroller and there ain't nothing wrong with that there saw!
As for driftin' off topic we all git along with it just so's we clean our boots before comin' in fer dinner!
~~~GB~~~
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Jim:
I agree with the above two replies, with the following qualification:
The circle falling out is a good metric that the blade is perpendicular to the table side-to-side. However if the blade is not perp. front to back you can still get the circle dropping thru the hole.
Think of it this way: if you are cutting a long straight line, if the blade is misaligned side to side then the curf will be angled with respect to the faces of the board. However, if the blade is misaligned front to back (but perp. side to side), then the curf will still be perp. to the faces. The result in the first case when you cut a circle, you wind up with a tapered cut out, not so in the second case.
Where the second case bites you is when you try to make very sharp turns.
Have fun,
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Alien11, of course. I didn't think of it that way but you're right about the blade only being proven vertical from side to side. It is as vertical front to back as I can make it and as I can measure it with my plastic protractor.
Graybeard, I wouldn't call myself an expert by any definition of the word but thanks for the compliment. As I said before, I was in no way upset by the "driftin' off topic".
When it comes to sharp turns, they never turn out to be sharp, they are rounded and don't hit the line coming away from the corner. That is certainly a lack of practice. I thought cutting patterns might be enough practice but now see the wisdom of making practice patterns of lines with many corners. I also have to re-watch Steve's video on corners.
Practice, practice, practice.
Jim
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Jim
Dan suggested a good way to make the square corners. When you get to the corner, back your blade up a little, then using the corner of the blade widen the kurf until you can turn the wood so that you are tracking down the line again. I usually do this 2 or 3 times depending on the size of the blade. The result is a nice square corner.
If I'm not happy with the line I can turn the wood around and go back the opposite direction and square it up with light cuts until I'm satisfied. I do this by going back to the place where I widened the kurf and can spin the wood without binding the blade then back the blade up to where I stopped and then cut back to the corner. See attached drawing.
Hope this helps.
Gabby
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Gabby,
Great idea, I will try it today. I still want to be able to spin the workpiece like Steve does so I have to practice, practice, practice.
Jim
(Now I'm going off topic!! ;D)
J
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Gabby,
Great idea, I will try it today. I still want to be able to spin the workpiece like Steve does so I have to practice, practice, practice.
Jim
(Now I'm going off topic!! ;D)
J
Not a problem, that's half the fun!
Gabby