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

[JPG]

Now if I were to get this jig and wanted to do my jointer knives at the recommended 38 degrees I would then have to adjust the table to what angle?

See photo below for how angle is measured.

IMG_1460scm.jpg

The assumption would be the knifes are flat, at least that is my best guess. So with that in mind talk me how to do the setup.

Ed

Assuming all the previous conclusions are correct(0 tilt yields 45°), raise the left side of the table 7°.

Does this take into consideration reible's statement that he assumes the knives are flat? If not, there needs to be a correction for the taper that is on the Shopsmith knives but not on reible's.

It does, but that is included in the original 45° assumption.

i.e. I did not include Ed's flat assumption.

[rcplaneguy]

Ok, here is a freshly sharpened planer blade with the conical disk, SS sharpening holder, and the table set at 0 degrees (flat).



Pretty close to 45 degrees.

[reible]

Are shopsmith planner blades flat or tapered? The jointer blades are tapered or so I've heard but I don't think the planner blades have be discussed in this respect.

Ed

[rcplaneguy]

Are shopsmith planner blades flat or tapered? The jointer blades are tapered or so I've heard but I don't think the planner blades have be discussed in this respect.

Ed

The end of the tapered planer blade is visible on the photo above. Zooming in...

[BuckeyeDennis]

I just measured the conical disc double-angle at 6 degrees, 50 minutes. So lets call it 7 degrees, giving an angle of 3.5 degrees on each side. Earlier, I measured the clamping surface of the sharpening jig at 43 degrees from horizontal. So if the table is set at zero degrees, you will grind an angle of 46.5 degrees to the clamping surface. This is precisely consistent with Dusty's measurement of a 1.5 degree taper on the Shopsmith blades, to give a 45 degree bevel (measured from the top side of the blade).

Reible's geometry is a bit simpler, because his blade is not tapered. Both sides of the blade are at the same angle as the jig clamping surface. So to grind a 38 degree angle, he needs to tilt the table to 46.5 - 38 = 8.5 degrees. Counterclockwise.

Edit: As JPG noted, a clockwise table tilt is needed!

[jsburger]

Ok, here is a freshly sharpened planer blade with the conical disk, SS sharpening holder, and the table set at 0 degrees (flat).



As best I can tell, 44 degrees.

Dusty started this thread because he read an article about jointer/planer blade sharpening angles.

He has by his own admission was sharpening them wrong according to SS. He apparently has had no problem with his blades over years even though the angle was not per SS specs.

The question is whether a 3 or 4* sharpening angle makes a real difference for the average wood worker. On a hand plane probably, on a jointer or planer maybe not. My opinion is no.

[JPG]

I just measured the conical disc double-angle at 6 degrees, 50 minutes. So lets call it 7 degrees, giving an angle of 3.5 degrees on each side. Earlier, I measured the clamping surface of the sharpening jig at 43 degrees from horizontal. So if the table is set at zero degrees, you will grind an angle of 46.5 degrees to the clamping surface. This is precisely consistent with Dusty's measurement of a 1.5 degree taper on the Shopsmith blades, to give a 45 degree bevel (measured from the top side of the blade).

Reible's geometry is a bit simpler, because his blade is not tapered. Both sides of the blade are at the same angle as the jig clamping surface. So to grind a 38 degree angle, he needs to tilt the table to 46.5 - 38 = 8.5 degrees. Counterclockwise.

Sure about that?

I say raise the left(disc) side.

[JPG]

Ok, here is a freshly sharpened planer blade with the conical disk, SS sharpening holder, and the table set at 0 degrees (flat).



As best I can tell, 44 degrees.

Dusty started this thread because he read an article about jointer/planer blade sharpening angles.

He has by his own admission was sharpening them wrong according to SS. He apparently has had no problem with his blades over years even though the angle was not per SS specs.

The question is whether a 3 or 4* sharpening angle makes a real difference for the average wood worker. On a hand plane probably, on a jointer or planer maybe not. My opinion is no.

The 'optimum' angle will vary with the wood being milled. The range goes both above and below 45°.

The angle will affect both tearout and blade wear.

I doubt any of us would be looking at those variables and making an informed decision re what angle to use. For sure we would not change blades for different tasks.

So I agree with JSB in that for most of us it just does not matter. 45° will do.

Again, sharp is what matters most.

P.S. Dusty created about 48° bevel angle. Good for soft woods.

[reible]

I have to confess to not actually sharpening my blades in a lot of year. I hone them but if they are bad off then it has been easier to just have them done. I have in the past done them on my grinder but that leaves them less then flat edge due to the diameter of the grinding wheel. I know a flat grind is better so if you send them out they take care of all that for you. Just like the manual says I would tell them 38 degrees and that is what I think they came back as. Another confession I have never measured them so hey maybe they are 45 degrees?????

I have two sets of the 6" and it has been a lot of years since had them actually sharpened and in fact the place I use to take them is no longer there. Hence my thinking about go back to basics and do them myself. I have the disk but not the knife holder so I could put that on my shopping list.

My planner blades are throw away type, well you can touch them up but if you do much more then honing they are a goner. So it would only be my jointer blades, both the 4" and the 6".

Again I have no idea why my jointer calls for the angle it does and my sharping book also calls for angles of less then 45 degrees but if I ever do get to do my own I think I will stay with those angles.

Anyone else reading here with a different brand jointer and if so what angle do they give you?

I guess I will add it the attachment to my list but also see if I can get a current price on having the knives done for me. If it is still pretty cheap then I don't know if I want to do it myself or if it would pay for itself.

Anyway it has been interesting.

Ed

[BuckeyeDennis]

I just measured the conical disc double-angle at 6 degrees, 50 minutes. So lets call it 7 degrees, giving an angle of 3.5 degrees on each side. Earlier, I measured the clamping surface of the sharpening jig at 43 degrees from horizontal. So if the table is set at zero degrees, you will grind an angle of 46.5 degrees to the clamping surface. This is precisely consistent with Dusty's measurement of a 1.5 degree taper on the Shopsmith blades, to give a 45 degree bevel (measured from the top side of the blade).

Reible's geometry is a bit simpler, because his blade is not tapered. Both sides of the blade are at the same angle as the jig clamping surface. So to grind a 38 degree angle, he needs to tilt the table to 46.5 - 38 = 8.5 degrees. Counterclockwise.

Sure about that?

I say raise the left(disc) side.

And you are correct. When I glanced at the the illustration from reible's manual, the angle looked less acute than the SS 45 degrees. But the actual dimensioning says it is more acute, and so a clockwise table tilt (disc side up) is needed.