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My latest blade grinding jig

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Derek Cohen (Perth Oz)

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I have posted this to the hand tools section in spite of the jig(s) being (horse) powered since it is designed for chisel and plane blades.

What is involved is the adaptation of a bench belt sander for grinding blade bevels.

I posted Mk I two months ago, and have just completed MkII. The first machine is easily made by the average woodworker, the second one also but does involve (simple) metal work. Essentially the same jig, although Mk II is an improved design. But read (at least some of the posts to) Mk I first to get the general idea, and for the discussions that followed (and were incorporated in Mk II).

The advantages of this jig are:

1. Firstly, it is cheaper than a Tormek (at 8 times the price of Mk I).

2. It runs cooler than a Bench Grinder and you have to be a complete Klutz to burn a blade.

3. You can grind a flat bevel as well as a hollow ground bevel, and the set up for either takes a few seconds.

4. The wide belt grinds the entire blade evenly (for a more even grind), unlike vertical wheels where you must move the blade across them.

Note that the grinder is to establish the primary bevel, and secondary bevels are honed with waterstones. Having said this, I find that I can sharpen chisels here sufficiently well to not need anything further.

Mk I: http://www.woodworkforums.ubeaut.com.au/showthread.php?t=14908&page=1&pp=15

Mk II: http://www.woodworkforums.ubeaut.com.au/showthread.php?p=135269#post135269

Let me know what you think (if you suffer through it all!).

Regards from Perth

Derek
 

Chris Knight

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Derek,

Well done, it is a great jig and as you say a lot more economical than a Tormek. Reading woodworking how-to books more than 10 years old, the use of a belt sander is frequently advocated for grinding/sharpening (though I haven't seen a jig like yours) but I guess the high priests of sharpening felt a bit snooty about it and it doesn't get a lot of press these days which is a shame because it works very well.
 

Derek Cohen (Perth Oz)

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Chris

I felt vindicated after seeing Tage Frid sharpen his chisels on a 220 grit belt sander (free hand!) then hone on a leather wheel, and then procede to cut all his dovetails.

Presently I go up to 600 grit sandpaper (I am looking to go up to 1200), which is already slightly better than a Tormek. Best of all, this process takes around 30 seconds.

Regards from Perth

Derek
 

Frank D.

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Very nice work Derek! I'm starting to consider various options to speed up sharpening, becoming less of a purist I guess. I like your system a lot, and although I definitely don't have room in my shop for such a big belt sander you've set off a few sparks in my mind on how to finally start using that handheld belt sander I have.
Thanks for posting,
Frank
 
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Anonymous

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Nice sharpening jig Derek. I have the exact same belt sander in my garage.
I think you can guess what I'll be making this afternoon :whistle:
 

Alf

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Spokeshave handles...? :-k :wink:

I'm having trouble with the site at the moment, but as soon as it lets me on again I look forward to seeing it, Derek.

Cheers, Alf

Edit: Now I see it. What a terrible idea. My hand cranked grinders would sulk! :wink: S'good. Funnily enough I've got one of those sanders too... :-k
 

Johnboy

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Excellent stuff Derek. I have a Tormek but use it mainly for woodturning tools so always have to true the wheel before grinding chisels or plane irons. Your jig looks ideal, simple to make and operate. Thanks for sharing it.

John
 

Mcluma

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I think i will get the beltsander out this weekend, make a quick jig and sharpen all my chisels,

That is a great idea, :lol: :p

I normally do them freehand on the grinding wheel, but as my wheel is not #true# any more, due to other jobs on it, i know the beltsander will be a great improvement :wink:
 

gidon

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Derek
I like the jig - at the moment I grind my primary bevel with a extra coarse DMT stone - but it's still pretty slow.
I'd read before that grinding a belt sander will overheat the metal and you have to continuously soak the blade in water - is this not the case? Also does the setup work well for flattening backs?
Cheers
Gidon
 

Derek Cohen (Perth Oz)

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Hi Gidon

While I always keep water on hand, grinding on the belt sander is a relatively cool affair. 8) The blade heats slowly and I usually dunk it in water when it is warm in my bare hand - just a precaution. Grinding with a belt sander is quite different to a bench grinder (nasty things! :evil: )

The coarser the belt grit, the cooler the grind. I begin with 80 grit on blades that require a complete regrind. It works fast - several seconds only - and then you can change belts to a higher grit. From 80 to 120 to 240 to 400 to 600. Each successive grind takes only a few seconds, and the blade never heats up much more than warm to the touch. You can hold it in you hand all the time.

My grinder jig was designed specifically to be able to change belts without losing the existing setup. You can regrind a poor bevel in a couple of minutes (something that might take you hours on sandpaper or waterstones).

Incidentally, if this was a chisel, I'd stop at 600 and hone on Veritas green rouge. This chisel will be sharp enough for anything you could ask of it(about the same as the best off a Tormek).

A plane blade, however, needs to be ground smooth as well as sharp, so I now take it to my waterstones. I can go directly to a 6000 King or a natural waterstone. Then onto the Honing Plate, and all is done.

Link below to the Honing Plate:
http://www.woodworkforums.ubeaut.com.au/attachment.php?attachmentid=6561

I have not yet tried to grind the backs of blades - I need to work out a jig first that will keep the blade flat to the belt.

Regards from Perth

Derek
 

gidon

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Hi Derek - thanks for the quick reply. I may just have to give this a go on my small handheld belt sander which I can clamp in my bench vise. I have a nasty feeling though that the platen is far from flat enough for this sort of thing!
I'm guessing Tony has the Perform model sold in the UK - now reduced to £50 so look forward to him checking it out! May be a nice addition to the workshop :).
All very intriguing - thanks Derek!
Cheers
Gidon
 

dickm

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Some years back, Elu made a combined dry stone grinder and what was effectively a belt sander specifically for tool sharpening. But I've never seen one, and they stopped being advertised quite quickly so I wonder if there was a snag with this idea?
 
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Thanks Derek

I made mine today and ground some 12mm Marples chisels into left and right skews for dovetails. Worked really well :D
 

Derek Cohen (Perth Oz)

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Good for you Tony. It gives me great pleasure when I hear that others find my jigs helpful.

Here is the latest development of the blade setting jigs I use with the belt sander grinder.

While I built these jigs for use with the belt sander blade grinder, they may be used with blade sharpening guides, such as the Veritas and Eclipse.

The attempt is to maintain (1) the blade perpendicular to the front of the blade holder/sharpening guide, and (2) precision angle setting. Here, the blades are extended a specific length. For example, for a 25 degree bevel on my belt sander, the blade is extended 31.5 mm over the front of the blade holder.

There are two jigs here:

The first is what I call The T-blade setting jig. This is a variation of many similar jigs on the internet. I made one but find that there is a potential problem with errors of parallax: as you look over the blade's bevel, which is bevel down, it is possible to make an error in measurement. Still, some may prefer this format.

http://www.woodworkforums.ubeaut.com.au/attachment.php?attachmentid=7949

The second jig was my fix for this problem. I call it The L-blade setting jig. The scale is now positioned to the side of the blade and in a vertical orientation. It is now easier to read the measurements accurately.

http://www.woodworkforums.ubeaut.com.au/attachment.php?attachmentid=7951

Let me know what you think.

Regards from Perth

Derek
 

Mike B

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Hi Derek

Great grinding jig and useful blade setting jigs.

Being a bit of a sharpening disaster area, I ended up making a jig in order to attempt to get a consistent bevel (or at least limit the variations in my case!) on my blades. I ended up with a similar idea although I used a 30cm long piece of MDF as a base/reference edge and glued several sets of small side and end stop blocks on it, one set for each blade angle projection I need. Now I don't need to measure each time - just pick the appropriate slot, reference the blade on the side and end stop blocks, and slide the holder to the reference edge of the MDF. Guess it just depends upon how many angles you require...

Mike
 
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