Author Topic: Troubleshooting DeWalt 788 Blade Movement  (Read 1624 times)

Offline RickKr

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Troubleshooting DeWalt 788 Blade Movement
« on: June 10, 2018, 05:24:47 pm »
I have a new DeWalt 788 that I've been learning some basics on scroll sawing.  I'm exploring a blade movement issue, that of the blade moving forward and backward through the stroke.  I've determined that the blade moves forward about 1/32" from the top to near the center/just below center of the stroke and then back again the bottom of the stroke, but not as far as at the top.  Here is a video documenting that movement.  The blade is essentially traveling in an arc, which I would have thought would not be the case, given the complex mechanics and geometry of the machine design.
https://vimeo.com/274311836

In this setup, a piece of brass 1/32" wide is held in the blade clamps upon which the indicator needle is riding.

I've read the DeWalt Tune-Up material on Rick Hutchenson's site (http://www.scrollsaws.com/) but what I am seeing does not seem to be the same thing.  I believe I read somewhere early on that the DeWalt has a design "feature" of the blade moving back away from the cut on the up stroke.  But as I'm learning by trying to make tight turns and from reading that such a blade movement is not conducive to making nice tight, sharp turns, such as at sharp points in patterns.  The blade is moving forward almost the distance of the blade width (#7 Olson PGT) and back again a little over half a blade width.  I can see how that is not good for making tight, crisp turns.

Has anyone observed this motion/behavior and is there anything that can be done about it?

If there is no fix for this, I am not wed to this saw and wonder if there are other saws out there that do not have this problem.

Rick
« Last Edit: June 10, 2018, 07:04:47 pm by RickKr »

Offline Norm Fengstad

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Re: Troubleshooting DeWalt 788 Blade Movement
« Reply #1 on: June 11, 2018, 08:03:03 am »
I also have a Dewalt and not been concerned about the back and forth movement. On tight turn I slow down and back of on my in feed pressure. 

Offline jscott2

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Re: Troubleshooting DeWalt 788 Blade Movement
« Reply #2 on: June 12, 2018, 09:06:59 am »
I have the Delta 60-694, the DW788 clone and have somewhat the same front-to-back blade movement.  The movement was larger but I followed the instructions on Rick's site http://www.scrollsaws.com/ under Dewalt Tuneup to elongate the lower arm mounting holes, and got it down to about 1/32". 

That was good enough for me until I cut Steve's "Jesus Loves" 3D pattern out of poplar.  Making the last cuts across the top of the base left some cut marks on part of the top of the base.  I like some front-to-back movement helps clear sawdust, especially on 1.5" thick wood.

Your mileage may vary.
Jim
Using a Delta 40-690 in the Montreal, Quebec (Canada) area

 

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