Shopsmith Forums

Hi all!

I recently had the knives for my SS jointer sharpened by a friend. He did good work, but unfortunately I have been working with some pretty rough oak and they are already dull again! As someone who is very new to sharpening his own tools I would like some advice. I am hoping to learn to sharpen them myself so I don't have to send them off all of the time.

How often should I expect to need to sharpen my jointer knives?
Is it more likely to need to sharpen them after working with reclaimed (i.e. lots of knots) wood vs rough-sawn (mill or lumber yard)?
How sharp is sharp enough?
How do I tell they are sharp enough to work with? Is there a reliable test method to use?
What are your opinions / experiences with the following methods for sharpening SS jointer knives?
- Using the belt sander + shop built jig (I do own a SS belt sander)
- Using the disk sander with a flat disk + shop build jig (I own two flat sanding disks)
- Using the conical sanding disk and jig from SS (I don't own one so I would prefer not to buy it if possible)
- Shop built jig or fixture + wetstones
- Sharpening on the jointer w/ wetstone or diamond stone (There are youtube videos showing this method but I'm dubious)
- Any other methods or tools you have used

I am concerned about several of the above methods (including the conical sander) because of the low grits available. Wetstones go way up in the stratosphere in terms of grits and I'm not sure where I need to stop in order to get the edge I need, but 150 grit from a sanding disk doesn't seem high enough.

I made a fixture last night to hold the jointer knives in place so I could use some wetstones I own to try to sharpen them but I'm very unsure I'm doing a good job with it. They don't seem particularly sharp and my stones are of the cheap variety you can buy at Lowes. I'm hoping to use my jointer this weekend but that's not going to be possible unless I can get the knives sharpened.

I appreciate any advice or help you guys can provide on this as I feel quite out of my depth!

My experience with both my jointer and my planer blades is that they hold an edge very well and don't require sharpening often. Over the past 30+ years, I've simply taken them to a pro to be sharpened when needed. I use both of them a lot and still get years of use between sharpening. I never use reclaimed wood that has been previously finished because hardened finishes are hard on the blades. I use only new wood and buy rough sawn wood whenever I am lucky enough to find it locally at a good price.
Right now I have about 80 board feet of rough sawn walnut in the garage and as soon as I get some warmer days, I'll drag it all outdoors and plane it to a nice finish.
Do whatever works for you so you can keep a sharp edge that works.

From some research I have done this morning I'm starting to lean towards the flat disk sander approach for grinding/re-surfacing them to remove nicks and such, then moving to my shop-made fixture and diamond stones for honing.

I find myself a little confused about the direction I should be sharpening the blades. Should I be dragging the stone "into" the edge I am attempting to sharpen or "away" from it? I've seen people sharpening in both directions online. "Away" makes the most sense to me (across the bevel and towards the tip of the blade) but I'm not sure why that is. Is that correct or am I way off?

I use the Sharpening Jig with the Conical Sanding Disk and really like the ease of sharpening the Planer and Jointer Knives. For the Jointer Knives all three can be sharpened together which makes it a breeze. Using the 150 grit works fine and only a light pass at a time is needed. If you wanted to use a finer grit paper you could cut one out using a conical disk paper as a pattern. As was noted using reclaimed wood, very hard wood and wood with knots will dull knives faster. The most important part of having a sharping system of your own is less down time. Of course you can also have a extra set of knives to avoid down time while one set is out for sharpening.

I built a jig for myself. It holds 3 blades.

The slot angle is such that the top of the blades run parallel and at same height to that piece of purple heart (?). The angle is based on the blade angle
itself ..which i forget at the moment. I think i put something on the purple heart riser to avoid sanding it away ..maybe aluminum foil. The screws on right side come into the slot and press the blades flat against slot wall.

In this configuration, the wet stone or diamond sharpener resting on both the blade and purple heart would be moved from right to left.

It worked well the one time i used it

b

I made something very similar myself. I'll try to upload a photo later today. It works ok, but I'm having trouble getting the height of the shim just right. I used duck tape to protect it from wear.

Yesterday I attempted to use my SS belt sander to sharpen the knives with some good success. I'm just not sure how sharp the blades really need to be. I'm hoping to hear from someone on that point in particular.

Here is a discussion from earlier about this topic- sorry i dont have a suggestion for test to determine sharpness. Though Im not recommending for others , you can feel the sharpness using your fingers

viewtopic.php?f=5&t=23398&p=268374&hili ... ng#p268374

b

For anyone that might want to know what I have eventually decided,...

I did the initial sharpening on my belt sander using a block with a slot cut in it that holds the blade at the right angle. I then used a jig I made to hold the blades at the proper angle (mine isn't perfect but it's good enough). I used 2000 grit sandpaper to honr.

The photo of oak is of a piece after joining. It looks pretty good to me and the jointer performed better so I guess the blades are sharp enough using this method. No telling how long they will stay sharp though.

Ithabks to those who commented! would still love to hear from someone who has been doing this a lot longer than me about how to tell if the blades are sharp enough for joining though.

My only concern using the Belt Sander like you have it set up is the direction the belt turns in relationship to the knife being sharpened. That setup would tend to have the knife shaving off the grit from the belt. When using the Strip Sander to sharpen Lathe Chisels it is run in reverse to avoid burying the sharp edge into the sanding belt. I don't know for sure if there is a problem running the Belt Sander in reverse but I believe the tension cam will not function properly in reverse.

Off hand I do not think the rotation direction has any effect on tension.