i've had my throatless shear for about 2 years now, and it has cut anything .090 and smaller without hesitation for many projects i have done. now, it has begun to dull, and it now just pushing the material between the two blades and not making a clean cut. i would like to sharpen these and re-temper them instead of paying for a new set of blades. can this be done, and how?
throatless shear blade sharpening
- Thread starter that-guy
- Start date
rsanter
Well-known member
You do not re-temper
Just grind lightly the the beveled cutting edge
You have to use a fairly fine and hard stone
Or better take them to a blade sharpener, most charge about $1 an inch
Bob
Just grind lightly the the beveled cutting edge
You have to use a fairly fine and hard stone
Or better take them to a blade sharpener, most charge about $1 an inch
Bob
Had a similar problem with the blades on this guy, after a couple of year's use.
The material would fold over and get pinched between the blades, rather than shear.
Solution was two-fold.......blades were sharpened with wet/dry sandpaper on a block, and shims were added so the blades actually "scrubbed" against each other ever so slightly.
The blade edges are 90* so it was very easy to maintain that angle. The blade was clamped to a flat surface with small elevation blocks underneath and the sandpaper block was cut square. It took a couple of tries to get the shimming thickness right...used cut outs from a bean can.
screen shot
The material would fold over and get pinched between the blades, rather than shear.
Solution was two-fold.......blades were sharpened with wet/dry sandpaper on a block, and shims were added so the blades actually "scrubbed" against each other ever so slightly.
The blade edges are 90* so it was very easy to maintain that angle. The blade was clamped to a flat surface with small elevation blocks underneath and the sandpaper block was cut square. It took a couple of tries to get the shimming thickness right...used cut outs from a bean can.
screen shot
Outlawmws
Well-known member
If you plan to use a grinder, you need to use a slow speed grinder, preferably wet. Not many people have that tool.... You need to avoid getting the blades hot or you will damage the temper at the edge and as mentioned, you don't re-temper them...
The wet/dry sandpaper is not a bad approach, just take more time... best if you can fixture the blade for a precise angle regardless of method.
The wet/dry sandpaper is not a bad approach, just take more time... best if you can fixture the blade for a precise angle regardless of method.
My HF shear's blades are not 90 degrees. I have sharpened them many times. The blades must be smooth and even. They should not touch when you operate them. I think I keep them seperated by about the thickness of a sheet of paper (.004"). I cut hardened spring steel on them.
Type of grinder does not matter. I think the blades are some form of high carbon steel- guessing O-1. Just be sure not to overheat it during grinding (which is what folks are warning against- and they are right; Some grinders, some wheels, do tend to overheat more than others. But this is more technique, e.g. wheel dressing etc than an equipment limitation).
I cut hardened spring steel on mine up to to .045 or so. It won't cut 1095 spring in that thickness for long.
I'st you're talking about a slitting shear not a throat less....
Beverly shears are throat less, they turn
lilredex;
ALL shears have clearance between the blades, dependent on the thickness of the material your cutting
you're breaking the material not slicing it....look at the cut edges
you only want to sharpen the top edge of the blades, even on big power shears......and the blades aren't 90* like Adam.C said, the back rake keeps the metal in place and the load down
my 30 year old German slitting shear has never been sharpened, my '20s Niagara 4', 14ga gap shear MAY have been sharpened, I don't know......if i tighten it up. it'll cut paper all the way across
if you want gap setting info try Machinery's Handbook
PS;
I collect exotic tin snips, so I've played with blade geometry
Beverly shears are throat less, they turn
lilredex;
ALL shears have clearance between the blades, dependent on the thickness of the material your cutting
you're breaking the material not slicing it....look at the cut edges
you only want to sharpen the top edge of the blades, even on big power shears......and the blades aren't 90* like Adam.C said, the back rake keeps the metal in place and the load down
my 30 year old German slitting shear has never been sharpened, my '20s Niagara 4', 14ga gap shear MAY have been sharpened, I don't know......if i tighten it up. it'll cut paper all the way across
if you want gap setting info try Machinery's Handbook
PS;
I collect exotic tin snips, so I've played with blade geometry
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Guess I should have left the 90* out of that reply....did not intend to start a controversy over angles (or shear types).
My objective was, to show how you could simply rejuvenate the blade's edge, maintaining the original angle, without a complicated grinding set up, with sandpaper and a block cut to the proper angle.
Unless you have been (foolishly) cutting wire or rods, the blades won't be nicked and likely only need a touch up.
Jointer blades and planer blades can be cleaned up in this way too.
And yes, I do know the difference between the two types of shears......I also have a Makita electric version of that "Beverly" type.
For the record, that bottom blade on the shear shown is symmetrical and ground at 90* top and bottom, giving you four edges to work with. Will have to check on that upper blade angle again, to be sure.
Will check out what Machinery's Handbook says about clearance, when I get my library back, out of storage. But for now, it does cut (OK), the way it did as new.
My objective was, to show how you could simply rejuvenate the blade's edge, maintaining the original angle, without a complicated grinding set up, with sandpaper and a block cut to the proper angle.
Unless you have been (foolishly) cutting wire or rods, the blades won't be nicked and likely only need a touch up.
Jointer blades and planer blades can be cleaned up in this way too.
And yes, I do know the difference between the two types of shears......I also have a Makita electric version of that "Beverly" type.
For the record, that bottom blade on the shear shown is symmetrical and ground at 90* top and bottom, giving you four edges to work with. Will have to check on that upper blade angle again, to be sure.
Will check out what Machinery's Handbook says about clearance, when I get my library back, out of storage. But for now, it does cut (OK), the way it did as new.