Shopsmith Forums

Reassemled, aligned and tested the jointer today. Man, that's a nice, clean cut! I am now, finally, finished with stage two, the restoration of my SPT's. Stage three will be the restoration and testing of all my accessories. Good thing I'm enjoying this because it sure is a lot of work.

Hi,

Just read the last couple of your posts on grinding jointer knifes and thought I should at least point out that you can only grind off so much of the knife, as in it has a minimum length.

Blades less then 11/16" wide need to be discarded. As shopsmith says, "further use is dangerous".

As far as grind angles, nominal is 45. Softwood can go to 47 or 48 degrees while you get longer lasting edges on hardwood at 42 to 43 degrees.

Heat build up while grinding is also an issue, if you have the knife turn blue then the temper will be lost and from then on it will dull very quickly.

It is recommended to hone the knife with a medium or fine whetstone before installing them.

Ed

Ed, I am aware of the 11/16" minimum length and am pretty close on the one blade I used to fine tune my grinding procedure. I have submitted an inquiry to a company that sells high speed steel blanks to see if they can provide them in the correct size for jointer knives and at a good price. If they can, I will report that here. I know they have them in 6" lengths but I'm hoping they will make a run of 4" pieces for sale.

Again, I don't know about aluminum oxide belts but the ceramic belt I used ran very cool. Never came close to bluing anything. I'm really liking this ceramic stuff.

I didn't hone the knives because, in my experience with metal working, tool bits get honed with use. Maybe it's different with wood but the test cuts I made were smooth as a baby's bottom so I'm happy with the result.

As far as the angle goes, my blades appeared to never have been reground. The angle was 40 degrees so that's what I went with. Anybody know what the angle is on a new set from Shopsmith?

emagnet wrote:Ed, I am aware of the 11/16" minimum length and am pretty close on the one blade I used to fine tune my grinding procedure. I have submitted an inquiry to a company that sells high speed steel blanks to see if they can provide them in the correct size for jointer knives and at a good price. If they can, I will report that here. I know they have them in 6" lengths but I'm hoping they will make a run of 4" pieces for sale.

Again, I don't know about aluminum oxide belts but the ceramic belt I used ran very cool. Never came close to bluing anything. I'm really liking this ceramic stuff.

I didn't hone the knives because, in my experience with metal working, tool bits get honed with use. Maybe it's different with wood but the test cuts I made were smooth as a baby's bottom so I'm happy with the result.

As far as the angle goes, my blades appeared to never have been reground. The angle was 40 degrees so that's what I went with. Anybody know what the angle is on a new set from Shopsmith?

ALL information in my previous post is straight out of the Power Tool Woodworking for Everyone, revised edition pages 337-338. As is the following.

"Replace worn out knives with Shopsmith Jointer knives. Use only Shopsmith jointer knives in the Shopsmith jointer. Other brands of knives will not seat properly in the cutterhead and can be extremely dangerous."

Ed

Ed, I am aware of those warnings. These are unbranded blanks, not some other brand of jointer knives. They would be the exact size and of equal or better quality to the Shopsmith brand at a cheaper price. Do you know of any company that does not recommend you use their brand on their products?

emagnet wrote:Ed, I am aware of those warnings. These are unbranded blanks, not some other brand of jointer knives. They would be the exact size and of equal or better quality to the Shopsmith brand at a cheaper price. Do you know of any company that does not recommend you use their brand on their products?

As I recall, the shopsmith knife has a reverse taper, and as such they are the only provider. I'm sure someone could do a special grind if they knew what the specifications were.... Going and getting a knife without the taper would be a risky situation.

I believe this has come up before and to my knowledge no one has come up with a second source much less a cheaper one. So if you do find one some people will be interested, just make sure you find the specifications to match the shopsmith knife.

Ed

You are correct. There is a taper on the knives. I'm betting I can come up with a way to grind that on the belt sander. Should be a fun experiment.

I would never do that, even if I have the skills and tools to try. I have neither, but my study of physics and two fairly minor kick backs on the saw, make then thought of a planer or jointer blade coming off is scary. Be careful!
I admire the skills it would take to do this as well.

Be careful and be critical of your end result. That taper is there for the purpose of holding the blade in place. I shutter to think of the possible consequences - all to avoid buying blades or a proper sharpener.

emagnet wrote:.... The SS is in my patio which is canted for water runoff. Over the length of the SS, the elevation drop is a full 2 inches. ...]

So you don't have to add on a Lift-Assist in that location!