Home made shapener (glorified lansky) pics: need advice

S

samgotit

Joined
May 11, 2005
Messages
27
Hello all,

So I had a ball cutting down a backyard full of banana trees and now I need to sharpen my BK7. I inherited a lansky sharpener but it won't work for long fixed blades, not enough reach and the stones are too short. I really like the lansky system (have not tried the spyderco) so I canabalized it and made this:

The sharpening rods are made with 2"x6" DMT Dia-sharp Diamond Sharpening Stones (fine and extra fine) epoxy glued to a wooden door knob which is drilled out and bolted to a threaded rod. If everything works out I'll make more rods with thinner stones for smaller blades.

I have a couple of questions for the more experienced. Please see the paragraph below the third picture. Feel free to criticize or make any suggestions.


sharpener%201.jpg


sharpener%205.jpg


sharpener%204.jpg



So far works great for me, a complete beginner. I have a few questions though?

In the picture below is how I set the angle. I use a protractor and the adjustable up/down dowel to set any angle. The vertex of the angle is measured at the blade edge. I placed the protractor flat along the width of the blade and in the picture below I read the angle as ~12 degrees (This is only an example). Is this a correct method for measuring the edge angle???

Sharpener%202.jpg


Below is how the angle is adjusted with wing nuts:

sharpener%203.jpg




Thanks,
Sam
 
it looks like a pretty good idea. I think it's great that people are finally putting the brains in it all and start to innovate. The angles are fine. It donesn't have to be exact. Here are some cool ideas to play with.

Try using fine sand paper (800- 1500 grit) glued on a board to give the edge a fine and hair popping finish

You can also glue a mouse pad between the sand paper and board. This allows you to do convex edges, which is great on larger knives
 
Interesting mod. If you want to make a bunch of plates for kidswholaughs wet/dry sandpaper idea look into cutting blanks out of 1/4" plate glass or 1/8" aluminum bar stock at whatever width works for you. As for angles, measure from the flats or the primary bevel or whatever, just be consistent with what you use. Well done!
 
I like it. Very creative and measuring from the grind to get the angle seem appropriate.

Cliff
 
Hi there
nice piece of creative thinking, use a magic marker and a magnifying glass to check if the sharpening angle is the same as the previous angle. search the forums for other ideas.
Phil
 
Good idea. You're angle measurement is low by whatever angle the side of the knife is ground to since you are resting the protractor on that surface rather than the horizontal center-line through the thickness of the blade, but if you write down your angle measurements, it should make it easy to set up for the same angle when you sharpen a particular knife again (you can measure the blade itself, use a little trigonometry and figure out how many degrees to add to your measurement if you really care all that much about the actual number of degrees, but consistancy seems more important than exact numbers)

The threaded rod can chew up your wooden cross beam. Maybe you can find something to put over that to protect it.... Or, hobby shops and some hardware stores sell thin-wall brass tube in 1 or 2 foot lengths (used for pipes in model airplanes and steam engines, table top fountains etc). If you can find a hunk of tube that will just slip over the threaded rods, it should protect your cross beam.
 
Groovy looking :) I would replace the threaded bar with a little I-Beam or box section of Aluminium from a DIY or hobby store and change the cross bar for something less prone to wear out, some kind of shaft would be ideal as its hard as hell and smooth. Other than that, you did great! :thumbup:
 
yuzuha said:
Good idea. You're angle measurement is low by whatever angle the side of the knife is ground to since you are resting the protractor on that surface rather than the horizontal center-line through the thickness of the blade,.
Click to expand...
This is exactly what I was curious about, but as you and others have mentioned it is probably best to keep consistency constant over worrying a lot about the actual angle. As you also mentioned it will be easy to adjust that angle and record it.

The cross member is getting a little chewed up. For a quick fix I think I'll wrap the rod in duct tape until I can get to a hobby shop.



Thanks for all the input! Will definatly try to make a few blank plates and use the fine grit sand papers. It would be very easy to attach the paper using double face tape.

Think I will also put a small leg on the front to prop it up for better clearance b/w the stone and table top.

BTW: I've got a real nice edge on my BK7 now. I dare to say better than factory. I don't believe I could have done it free hand as a beginner.


Thanks all,
Sam
 
That is a cool gadget. Wish I'd thought of it.

As for angle measurement, if you're happy with the system you've got, bless you. Me, I'm anal. If I had that rig I would have to know what my angle really was.

Trigonometry is your friend for work like that. Here's what I'd be tempted to do. Clamp the blade in and get a ruler/meter stick long enough to measure from the blade to the crossbar. You want the distance from the blade edge to where the measuring stick rests on the crossbar, at whatever level of precision floats your boat. Me, I'm anal, but I mentioned that :cool: so I'd go with 16ths of an inch, or millimeters. Now it's calculator time. You want the height of the crossbar above the blade centerline to be a certain ratio of that distance you measured from the crossbar to the edge. If you recall your highschool math, it's the sine of the angle. So knowing the sines of various angles, you can figure out how high to set the crossbar to get a given angle.

Sines (to four decimal places) for sample angles:
sin 12° = .2079
sin 15° = .2588
sin 20° = .3420
sin 25° = .4226

Example: Suppose you measured 18½ inches from the crossbar to the blade edge and you want a 20° angle. Multiply 18½ by .3420 and you'll get a result close to 6 5/16ths. That's how high the crossbar needs to be.

Yeah. Gotta make me one of those.
 
Nice rig, but I'm looking at it and wondering how much variance you get in angle as you come around towards the point of the blade, I'm not so good at geometry, but would the changing length of the hypotenuse necessarily change the angle of the sharpening surface relative to the base? I.E. as the distance between the upper support and the blade/sharpener interface increases and decreases the angle should also increase and decrease.

Seems like the upper support should include some sort of horizontal feed and also would need to have a different profile to match the curve of the blade. Then again like I said I'm not that good at geometry ;)
 
I wouldn't worry too much about the grind angle of the blade. First of all it applies pretty much only to blades with a full flat grind. On a saber or hollow grind, you usually have a flat part of the blade that you can rest your protractor on. Secondly, even on a thick blade like the Manix, you are adding only 3 deg. per side. I doubt that you will notice a big difference in 3 deg, and you can always subtract another 2 or 3 degrees just to be on the safe side. E.g. if you are aiming for 15 deg. and you have a full flat ground blade you simply rest the protractor on the blade and set the jig to 12 deg.

Nice rig you made yourself there!
 
Interesting topic. I have been cogitating a homemade sharpener more along the lines of a spyderco style. Yours looks great.
 
If you're using a smooth hard surface for your blanks (aluminum for example) you might look into one of the spray adhesives rather than two sided tape. If you spray it on just one surface (blank or sandpaper) it'll peel right off when you're ready to remove the paper. Works well and you won't have to cut something to size like you would with tape. Have fun playing with it!
 
Somebody tell me if I am seeing this wrong, but aren't the red lines the actual 12 degree angle measurement on the protractor, whereas the green line are what he is measuring now, a wider angle?:confused: I measure an angle with a protractor from the printed line with a hole through it, not the bottom of the protractor edge. I think there is an extra 6 degrees or so in the measurement.

Besides that, I think it is a great setup, very creative.

 
Oh......yeah! Totally missed that. Ya, that protractor is pretty much useless, but www.leevalley.com has a very nice protractor for $3. And you can probably find one in a good stationary supply aswell.


But the red lines aren't right either. The upper leg of the red set is not parallel to the the "abrasive medium". You have to find the angle between the lower red and the upper green (which is the same as between the two green, but the scale isn't reading that angle properly), but the protractor has no scale to measure that. Either you chop of the protractor or you buy a new one.

On my screen it looks currently like a little bit over 19 deg.

Such a nice rig is well worth a nice protractor, me thinks.

This one is nice
http://www.leevalley.com/wood/page.aspx?c=2&p=32582&cat=1,43513,51657
but I like this one better, even though it is cheaper:
http://www.leevalley.com/wood/page.aspx?c=2&p=32581&cat=1,43513,51657
 
HoB, I was having a hard time trying to figure out how to explain what I thinking. The red lines apply only to the protractor, not the equipment behind. I was more or less trying to show where to start the measurement from, the hole in the protractor. The only way I see to use this protractor is like you said, chop the bottom off, or clamp something else thin and flat and same depth as the blade(piece of sheetmetal or even cardboard?) that would be flush with the edge of the stone so you could put the protractor hole on the intersection point. Think breaking the BK7 off at the tang/cross section and then measuring from the hole. You could set the angle, then replace it with the blade to be sharpened.
 
ROM831 said:
Somebody tell me if I am seeing this wrong, but aren't the red lines the actual 12 degree angle measurement on the protractor, whereas the green line are what he is measuring now, a wider angle?:confused: I measure an angle with a protractor from the printed line with a hole through it, not the bottom of the protractor edge. I think there is an extra 6 degrees or so in the measurement.
Click to expand...


You are exactly right! I have to modify the protactor or get one from lee valley. That kind of oversight is exactly why I posted the technique for making the measurement. Thanks!

It's hard to tell for sure but I think this protractor would work. Looks like the vertex mark is at the base.
http://www.officedepot.com/ddSKU.do...chFlag=true&Ntt=+Protractor&x=46&y=15&An=text

Sam
 
Sam, a little clarification. That Office Depot protractor would work if you could hold the base of it along the centerline of the blade--not the secondary bevel--and put the zero point index mark where the sharpening surface meets the blade edge. But you can't do that. The blade itself gets in the way. You can offset a little to compensate, but now you're guessing at two things, the parallel hold and the offset. It's the same problem you have with the protractor you have now. A new one won't solve it. It's just one of those situations where the angle doesn't lend itself to accurate measurement with a protractor.
 
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