Using the Conical Disk along with the Planer/ Jointer Knife Sharpener

[dusty]

Post Deleted...rather than debate.

[JPG]

Here we go looking through the microscope glass!

First, what is magic about 45°?

Second that blade taper is likely slight(near 0).

Third SS cannot tell the difference between 4° and a little over 3°.


So what determines the grind angle?

The conical disc itself.

The table tilt.

The 'sharpener' blade mount angle.

All contribute to the final result.

I have always thought a slightly smaller angle was preferable(40°+).





Bottom line - a combination of 'things' determine the grind angle. To get out of over worrying zone, check the angle after grinding and determine if it works. Take notes and do the same the next time.







Think 'sharp' is more important.

[JPG]

Sorry folks. Dusty is apparently off his meds again.

For those of you who missed his initial post, he read somewhere that a 45° bevel is best for planing...

That got him to realize the SS jig, the Conical disk and possibly the tapered sides of the SS blades affect the resultant grind. Doing research into SS documentation caused him to want 'discussion' regarding the result of following those instructions.(0 table tilt).

He apparently did not like my response.

[ERLover]

I read an article that putting and addition bevel, I guess thats called a micro bevel I believe, right near the edge gives the best results. I think they never mentioned the degree of angles.

[reible]

For what it might be worth I got out my booklet for a non-shopsmith jointer and they call for 38 degrees. I've never even measured mine to see what angle they are at, it's easier to match the angle and grind.

I've read that some people like this angle or that angle but I've never taken the time to play with that aspect of the task on jointer blades. Lazy or just too many things to have to deal with I don't know.

I think from memory we did the jointer at about 40 degrees back at home with a machine that reminds me of the shopsmith one, but, it was just a pain in the (fill in your favorite word here) to get the knives set right that I developed a dislike for jointers that is still with me today.

I have a sharpening book that says 35 to 40 but what do they know?

Now did I take my meds yet today?

Ed

[jsburger]

Sorry folks. Dusty is apparently off his meds again.

For those of you who missed his initial post, he read somewhere that a 45° bevel is best for planing...

That got him to realize the SS jig, the Conical disk and possibly the tapered sides of the SS blades affect the resultant grind. Doing research into SS documentation caused him to want 'discussion' regarding the result of following those instructions.(0 table tilt).

He apparently did not like my response.

I don't understand his conclusion either that the SS documents are in conflict.

If you are edge sanding a piece of wood you want the edge to be parallel to the conical (tapered) disk so that edge is 90* to the face. Hence the need to tilt the table. The reason for the conical disk is so the stock only touches the disk at one point. Prior to the conical disk one used that infamous set screw on the fence to off set the fence so the stock only contacted the FLAT disk at one point. That meant you only used the very outer edge of the disk all the time. With the conical disk you can raise or lower the table and use the entire piece of sand paper on the disk.

Blade sharpening has nothing to do with keeping two edges/faces at 90*. In fact it is exactly opposite. I would assume that SS has figured out all the incorporated angles (Conical disk, table, sharpening guide) to make the sharpening guide work properly. I have used the sharpening guide (using the SS instructions) on my planer and jointer blades, including my Powermatic 6" jointer blades, for years with no problem.

[rcplaneguy]

Whatever the resultant angle is, the SS conical Disk and knife holder works like a charm, for me. Nice to be able to sharpen them up at home!

Has anyone tried out these blades?
https://mywoodcutters.com/Replacement_K ... aner_M5082

[reible]

Here is what I found on the shopsmith site:

"As a point of information, Shopsmith Jointer Knives are factory ground with a straight bevel
at 45-degrees. This is a multipurpose cutting angle that will produce smooth cuts at a variety of
speeds in both hard and soft woods. The straight bevel (rather than a hollow-ground bevel typically
produced by a grinding wheel) offers more steel backing up the cutting edge. This helps to produce a
longer-lasting cutting edge.
Depending on the materials you work with, you may wish to change this angle slightly. If you
work entirely with soft woods, 47 to 48-degrees will give a smooth cut. If you work entirely with
hard woods, try grinding your knives at 42 to 43-degrees."

I guess one has to figure out the angles if you want to make changes, I personally have none of this hardware so I will bow out at this point.

Ed

[jsburger]

Here is what I found on the shopsmith site:

"As a point of information, Shopsmith Jointer Knives are factory ground with a straight bevel
at 45-degrees. This is a multipurpose cutting angle that will produce smooth cuts at a variety of
speeds in both hard and soft woods. The straight bevel (rather than a hollow-ground bevel typically
produced by a grinding wheel) offers more steel backing up the cutting edge. This helps to produce a
longer-lasting cutting edge.
Depending on the materials you work with, you may wish to change this angle slightly. If you
work entirely with soft woods, 47 to 48-degrees will give a smooth cut. If you work entirely with
hard woods, try grinding your knives at 42 to 43-degrees."

I guess one has to figure out the angles if you want to make changes, I personally have none of this hardware so I will bow out at this point.

Ed

Nice find Ed and I think you don't necessarily agree with it, here is my take.

Since most of us work with a huge verity of wood, it sounds like 45* is just fine. I never take something off the planer or jointer to a finished product. The drum sander and probably the ROS and some hand sanding. I certainly am not going to change the blades on my jointer or planer depending on the wood.

[JPG]

Missing so far here is the angle the blade is mounted into the cutting head. Angle of attack do to speak.

Not that it is anything we can change, but it does enter into back side clearance 'figuring'.

At shallow depth cutting I would assume the 'attack' angle is slightly greater than the blade mounting angle.

FWIW SS procedure does not specify any resultant angles.