Tuesday, September 25, 2012

Belt Sander Sharpening


Belt Sander Sharpener --- My Version
      Jamie once said "ask 10 woodworkers how to sharpen a tool and you'll get 12 answers"; boy, isn't that the truth!  When it comes to sharpening there's no shortage of methods we employ to achieve that keen edge that will slice right through the toughest of wood fibers, cleanly and effortlessly.  Kind of like Monty Python seeking the holy grail isn't it?
     For all of my flat blades I prefer using Japanese water stones and guides only, I'm not a fan of hollow grinding on a wheel.  Yes it's more time consuming but it suits me and my method of woodworking.  The only time I ever use power grinding on a chisel would have been for my carpentry chisels that gets into a fight with the occasional nail and loses!
     Carving chisels and gouges present a different set of problems.  When they're factory fresh, so to speak, the bevel is uniform and occasional honing  or stropping keeps them cutting well.  As time goes on though the edge will tend to roll over making it harder to slice through the wood.  Many times it's desirable to lengthen the bevel or change it slightly to suit your own angle of attack.  I've been working on that and for me, getting a uniform bevel by hand has proven difficult.  So, back to the web and books to do some research.
     In Leonard Lee's book on sharpening he talks about how the belt sander is an excellent but over-looked method you can use to sharpen tools.  I used this as a starting point and the more I checked it out, the more attractive it became to me.  Lee Valley sells a 1" x 42" belt sander without a motor but there are any number of places that sell a 1" x 30" belt sander starting at $30.00 or so from Harbor Freight to the $400.00 or more range.  I opted for one from Enco which looks similar to almost every other 1x30 sander on the market.  Before I get into the details of this sander, another thing that makes this concept attractive is Lee Valley's offerings of sharpening belts.  Here's a LINK to them, they're reasonably priced and since power sharpening is not an everyday process they will be less costly than buying quality grinding wheels.
     According to safe practices, when you're sharpening it's better to have the rotation of the belt going away from you.  The tool rest that comes with the sander can't be tilted to a steep enough angle anyway, even if the belt was rotating the correct way.  That's why I made this plywood enclosure and bolted the belt sander to the back of it.  This way the belt is rotating away from the blade and by coming up with this tool rest I can also achieve the required angles. I wanted to leave enough room on the side to make belt changing easy.  Making the tool rest had me doing my share of head scratching!  I had the piece of perforated piece of angle iron from some long ago project so decided it would be the base.  Knowing that the closer I could get it to the belt the safer it would be is why I notched it out as shown.  You can see it better in this picture:

Parts other than the Housing

     The other parts are a 3/8" all thread with fender washers and a wing nut.  Next to the tool rest is a guide that will help keep the chisel square to the belt.  It can be bolted through one of the elongated holes so that makes it adjustable.  The MDF pieces that are labeled with the angles on them is what I came up with to support the tool rest.  Trying to create a pivot point wasn't possible because the distance between the rest and the belt would increase/decrease.
     If I "deconstruct" the process of setting it up it may be easier to understand.  First of all, the rod is run through the holes:

Step One:  Insert Rod

          As the rod is threaded through, you also thread in the desired angled rest:

Step Two:  25 Degree Rest Installed

     Push the threaded rod all the way through both of the rests and sides of the box:

Step Three:  Insert Rod Completely Through Unit

          Lay the metal tool rest on top of the angled blocks:

Step Four:  Tool Rest in Place

     Now you can tighten the wing nut securely.  Since there is some flex at the ends of the plywood box it's easy to get a good, tight hold.  If needed you can also fine tune the angle of the rest to the sanding belt.

Final Tightening & Adjusting of Tool Rest

     So, how does this all work?  Well, so far I've been really pleased but can't give it a full test until I get the sharpening belts from Lee Valley.  Using an 80 grit belt I just had to see what would happen.  Even though I won't use this on flat edges the chisel on the right is a garage sale item that I use to scrape glue off of projects once it's set up.  You can see it has a nice scratch pattern.  The two carving chisels are part of a quality, 11 piece set from Harbor Freight which I think set me back about eight bucks!
    

Check it Out!
     You can see the middle chisel got burned a bit on the lower left edge, the other stuff is rust.  That occurred because the handle got hung up on the tool rest since these chisels are very short.  No problem with the one on the left, I was able to get a uniform bevel all the way around.  This was one pass only, a second pass will eliminate the low spot in the middle.  I'm positive that when I get the blue zirconium belts from Lee Valley they will work fine.  Then just a honing and removal of the burr on the inside of the edge and it should be good to go.
     The question though is: will it cut?  Check this out and tell me what you think:

It Works!!
     Keep in mind that this is one of China's finest tools, I'm pretty sure the final grind on it is done on the street from the back of a moving truck!












7 comments:

  1. Excellent John!

    Can't wait to hear how the belts from Lee Valley work.


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  2. I use this method with the sander in the usual mode and am quite happy with it. I only use the blue zirconium belts to shape HS Steel, though. A linen belt (from Klingspor's) with polishing compound puts on a fantastic edge. A fine grit Aluminum Oxide belt would also do a good job. I free hand it.

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  3. I'll check out the belts from Klingspor, thanks!

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  4. Thank you for your post.it is a very interesting post.
    Belt Sander

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  5. Thanks for the post. I have ruined a jointer knife trying to get an edge on it using my 1" sander. This is just what I need or at least worth a try.

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  6. Thanks for the informative post . I am also a blogger and i wrote on belt sander . This post is really awesome .

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  7. Oh! I always practice wrong steps. Thank for your this article, i recognize that i need to change the run way of belt sanders! Thanks author!

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