Dispoz-a-blade confusion

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Forum topic by BHMLAFAYETTE posted 12-05-2013 02:44 PM 2734 views 0 times favorited 5 replies Add to Favorites Watch
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2 posts in 1831 days

12-05-2013 02:44 PM

I recently purchased a Jet pm-13cs planer and after some reading online, I ordered a Dispoz-a-blade unit for it. I purchased it from Amazon so I can easily return it. My confusion is the difference between the posi-set and the self-set.

Self-set has tabs on the blade holder that indexes the blade to the outer edge of the round cylinder. The posi-set does not have these tabs and is indexed by the bottom of the pocket the blades sit it. From what I read, the posi-set requires measurements to be taken of the pocket depth to have the blade holders custom fit. I am just not sure if this applies to all planers or just certain planers.

When I ordered the set, there was no questions or info about needing to measure. Can anyone clarify…

Thanks and I am proud to finally have a reason to join this informative website. Hopefully I do not become a nuisance and can one day start answering questions.

5 replies so far

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810 posts in 2101 days

#1 posted 12-05-2013 03:54 PM

I bought a Powermatic planer used, it came with the self set style blades. Those are like standard solid blades where the cutting heads jack screws are used to set each blades height. The gage above is probably the best way to set them. The holders with the posi-set have the flange that bears against the head. So, no gage needed, just make sure that flange is seated on the head when the gib screw are snugged. As—a knife tends to want to raise up some, may have to tap the holder down as the gib screws are tightened. On my planer, the many other adjustments are sensitive, to, and based off of the blade height. So, I would think on other planers it would be important for the knife height to be at what the maker says it should be. That said, many don’t like this system, but it is working just fine for me, but not exactly as easy to set as they claim.

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810 posts in 2101 days

#2 posted 12-05-2013 04:08 PM

I think I have the posi set- no tab or flange on the holders.

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2 posts in 1831 days

#3 posted 12-05-2013 04:09 PM

Thanks Unbob. I figured I would still have to check and set the blade height even with this system. No different than when installing a brand new original blade. The only benefit I can see is that the replacement blades are cheaper. If you will go through enough sets to cover the $200 + cost of the disposablade system.

That is a nice gauge you have there. Do you know where you purchased that?

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13640 posts in 3538 days

#4 posted 12-05-2013 04:21 PM

i got the set for my 20” planer
when they first came out
it came with some pre-cut short ‘plugs’
from metal rod (different lengths for different cutter heads)
that are meant to be ‘dental’ glued into the cutter head
(i can’t remember but they may be magnetic)
they stop the dispoz-a-blade holder
to the same place when switching out the knives
before tightening the gibb screws

so far they seem to work just fine

never even heard about the new ones till now

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

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810 posts in 2101 days

#5 posted 12-05-2013 04:23 PM

The gage is an old indicator I had on hand, I fabricated the base from a piece of scrap bronze.
One can be made up with a $12 harbor freight dial indicator and a hardwood base shaped into a V, it would work just as well. The base doesn’t have to be dead centered, just reasonably centered for the indicator.

These knives were already installed on my planer. The original jack screws in place-no solid plugs. An observation, these knives are thin, when snugged down they end up wavy, but when run, the high spots push down. I just indicate them in on the ends, otherwise trying to get them true the full length can be frustrating.

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