• posted on April 20, 2007, 9:38 pm
I was looking at those aftermarket shelix jointer cutterheads, and there are a few things that are bugging me.
First, how do you get a flat cut with them (as opposed to a plain helix, where the cutters aren't twisted to "slice" the wood)? Any time you take a straight blade on a cylinder and twist it away from the axis of the cylinder, the *ends* of the blade are going to stick out further than the center. To help visualize this, imagine if your 6" jointer knifes were turned in a helical way (for example, with the right edge hitting the workpiece first, and the left edge last) so that they "sliced" through the wood. Now, imagine that they were *really* turned... like 45 degrees. In your mind's eye, do you see how the ends of the blade would cut deeper than the middle? It seems like that would happen on even short blades like those on the shelix, so that you'd get a slight wave (or anti-cove) effect on the workpiece. Of course, they could fix this by making very carefully curved cutter inserts, but I've never seen any ads for "shelix" inserts versus the "helix" ones, so I'm not sure that they're doing this. Can anyone shed some light on this?
Second, how do you make the cutterhead parallel with the table along its width? With my existing knife-type cutterhead, I'm able to use jack screws or a magnetic knife setter to adjust this. It appears that, with a shelix (or a plain helix, for that matter), if the bearing seats aren't perfectly parallel with the width of your table, you've got problems. How do you solve this? Do you put shims under the bearings? Do you tweak the table? What?
Lastly, are the individual cutter-squares usually carbide or just HSS?
- Joe

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• posted on April 22, 2007, 11:51 am
Joe,

Not having seen one - but read reviews on them like the very good one from David Eisan, I would think the effective cutting surface is at the same effective distance from a flat reference surface. They don't actually take equal length cutters and twist them - they make the cutter surface in a twisted form. And in the cases of I think the one David had, a series of smaller cutters, arranged around the head, but again with the cutting surface equidistant from an opposing flat reference surface.
Love to be corrected (educated..)
Mike Brisbane Aus