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Thread: Niagara stomp shear. Blade sharpening. General info needed.

  1. #1
    MichaelP is online now Titanium
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    Default Niagara stomp shear. Blade sharpening. General info needed.

    I've just bought a 2' old Niagara stomp (foot) shear. After cleaning, some adjustments and lubrication, I thought I should sharpen the blades.

    I would prefer to lick the faces of the blades (the surfaces that face each other) before grinding the tops to sharpen the edges. Usually, people mention using shims if the thickness of the cutting edge was modified. It looks like this particular shear design allows to move the table along with the stationary blade back and forth to regulate the gap between the blades. I cannot see why any shim may be needed to compensate for face grinding in this case. Yes, I realize that some shimming might be required to correct bowing of the movable blade, but it has nothing to do with my grinding the blade faces. Am I missing anything?

    I'm also trying to verify the maximum rated capacity of the shear, but cannot find the data. I sent a request to BCN, but don't hold my breath: the shear is quite old with its Ser.# 7977. The blades are 26" long. Does anybody has any info on this model?

    Thank you.

    Mike
    Attached Thumbnails Attached Thumbnails shear-left-side.jpg   shear-right-side.jpg  

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    peterve's Avatar
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    I think capacity depends a lott on your weight
    So I think the average capacity of those shears increased substantialy from the YOM to now

    in general you shim the blade on the table in hight
    So the top of the blade is flush with the table
    I prefere a little (say about 0.1mm) under the table so the back cutting edge of the blade does not get blund from all the sheets sliding over it and you can use all 4 sides

    on most shears you can adjust the upper knive to get it ecaxtly parrallel with the lower knive
    That is you have bolts pulling the knive to the back and right next to them you have a bolt pushing
    Or hollow big bolt pushing and another one through the hole pulling
    But as this is a small one it is possible it is missing this feature

    Peter from Holland

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    Looks about the same beefiness as my 16 GA X 32" Pexto. If you need more than one 250 lb operator to cut it, it's too thick.
    Ray Behner likes this.

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    Shears do have clearance settings for the 'front' of the blade depending on material thickness(max. capacity). You should be able to Google up that info if you don't have the manual. Setting it to far apart, you will have a helluva burr, even with sharp blades, set it to close and you will have premature wear. Regards, Mike

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    gbent's Avatar
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    If you get lucky you will find at least one set of edges on your blades are still sharp.

    I just turned the blades on my shear. Luckily, only the 1st edge had been used since resharpening. The blades had been resharpened on the width, not the thickness. There were shims under the blades to make up for the amount lost to grind.

    My shear is a 10 gage x 4' capacity power shear and the directions call for .005 clearance on the ends and .004 in the middle.

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    Clearance is 5 to 8% for steel up to 450 N/mm˛
    Thats regular steel

    peter from holland

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    I should add that I have used shears that blade clearance was adjustable on the fly, so if you were shearing 1/8" sheet steel and then went to 1/4" plate, you would change the blade clearance via a lever and a locking knob. Wish I could remember the make. Regards, Mike

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    MichaelP is online now Titanium
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    Guys,

    Thank you for your efforts to help me.

    I guess I wasn't clear enough when I asked my question. Let me try again.

    My shear has screws that let me adjust the table position back and forth. The lower blade is attached to the table. To my understanding, this adjustment exists for the sole purpose of adjusting the blade gap and parallelism. In addition to this, the lower blade can be raised and lowered because it has oval holes for the bolts it's attached to the table with. I also realize that the moving blade is often need to be shimmed in the middle to compensate for bowing during cutting.

    Now, everywhere I read about shear blade sharpening, people mention that if the facing surfaces are ground in addition to the edges, shimming becomes necessary. With my shear design where the gap is adjusted through the table movement, I don't see why any additional shimming would be necessary. Am I right or there is something I'm missing?

    Frankly, I don't even know if non-adjustable shears exist at all. So where this advice to compensate loss of blade thickness by shimming comes from?

    P.S. It's not a question if a gap is needed or what size it should be. I'm aware of the importance of proper gap sizing.

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    mixdenny is offline Cast Iron
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    If there is a model number cast in, it will usually indicate the capacity, i.e., a 218 would be 2' and 18 gauge. I have been shopping for a shear for the past year* and have not seen the exact one you have for sale, nor pictured on any of the metalworking web sites that discuss shears. It does have a holddown, many shears 30" or under don't have one, and the construction is solid, so I'm going with 16 gauge. The FAMCO that size is only rated for 18 gauge, but is visibly less robust.

    Every foot shear I have seen uses the same adjustment method. The PEXTO manual does not mention any shimming, although they use an adjustable truss on the back of the blade carrier to set the tension.

    * I finally got a 36" shear at auction for next to nothing and had to dissasemble it into parts to carry it into my Scion, so I'm intimately familiar with their construction.

    Dennis

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    Michael, it appears to me you are correct about not having to shim for thickness grinding, provided your table has sufficient movement. You will have to shim to make up whatever is ground off the height.

    I really like the mechanical hold down handle. Convenient location for balance to get a really good jump on the foot pedal. Since the replacement foot pedal is hot rolled angle rather than cast iron, a previous owner must have gotten to good of jump.

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    Think about this... the only thing that is ground when a blade is sharpened is the narrowest faces, which does not change it's thickness. If the wide faces of the blade are ground,making the blade thinner and there are no provisions to set clearance, that is when shimming would come into play. Mike

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    MichaelP is online now Titanium
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    Mike,

    Actually, almost everyone suggests to touch the wide face (thickness) prior to grinding the narrow surface. This will assure the highest quality of the cutting edge.

    As for shimming, are you aware of any shear which has no means to adjust the gap short of using shims?

    I'm trying to understand why any mentioning of blade thickness change always leads to suggestion to compensate it with a shim (without any mentioning of other types of gap adjustment). If non-adjustable shears were common, this standard advice wouldn't sound strange. But if a non-adjustable shear is a rarity, why would they mention shimming in all discussions?
    ++++++++
    And there's one more question I meant to ask. My friend mentioned that if a HSS blade has a chip-off which is too large to be eliminated by grinding, it can be safely filled by welding prior to blade sharpening. Is it a commonly accepted method? I had my doubts (hardness change issue in HAZ), yet we know how hard the weldments are. Can you guys comment on this?

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    All of the people I've ever used to sharpen shear blades have simply used a stone to remove the burr after grinding, it eliminates a setup. I'm not sure you and I are on the same terms when you reference"gap"? Regards, Mike

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    MichaelP is online now Titanium
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    We are. Gap is the distance between wide faces of the blades. The blades are not supposed to touch each other in the area of crossing. The distance between them is the gap. So we're on the same page in this respect. Naturally, I wouldn't ask the question if I planned on leaving the wide faces alone and just stoning the bur away.

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    Heavey Metal is offline Titanium
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    Shiming will be necesary if the blade thickness is narrower than the seat as the 2 seats will hit in use.

    Not necessary if after grinding the blade still protrudes past the seat.

    Take a piece of materal the thickness that you will be shearing and cut short pieces of it along the blade and shim adj til you are happy with the bur.

    Do not weld the blade unless you have heattreat facilities and the necessary knowlege to do it.

    Hopefully it will have a sharp edge left and you can just turn it.

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    omrc7771's Avatar
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    Michael, In almost all cases, ONLY the top and bottom of the blade are ground, the faces..vertical surfaces, are left untouched......except for using a stone on them to remove the burr after the top and bottom are ground. there is no reason to grind any "faces" unless the blade is chipped and welded as a repair. I agree that no shimming should be needed on the stationary blade if the whole table can be adjusted in and out,however once the stationary blade becomes too narrow as to sit below the table, either shims or jack screws are used to bring it up flush to the top of the table. Regards, Mike

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    mach2 is offline Cast Iron
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    I have similar shear except its frame will handle continuous lengths. The foot stomp is designed to be wood. I used a 2x6 for replacement.

    The blades were sharp when I got the shear. It took about an hour to Adjust the blades. Worked at it til I could cut a piece of paper. Never have had a problem.

    The niagra is defiantly heavy built.

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    metlmunchr is offline Diamond
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    Quote Originally Posted by omrc7771 View Post
    I should add that I have used shears that blade clearance was adjustable on the fly, so if you were shearing 1/8" sheet steel and then went to 1/4" plate, you would change the blade clearance via a lever and a locking knob. Wish I could remember the make. Regards, Mike
    We've got a 1/4" x 12 ft Pearson hydraulic, made in England, that has a lever with 4 clearance settings for 1/4, 3/16, 11ga. and 16ga.

  19. #19
    metlmunchr is offline Diamond
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    Re the thickness capacity, it'd be rare for it to be more than 16 ga mild steel. As a general rule, you can shear 1.5 times that thickness in aluminum unless the material is 2024 or 7075. Stainless capacity will be 2/3 the mild steel capacity, or roughly 20 ga.

    Quote Originally Posted by MichaelP View Post
    Actually, almost everyone suggests to touch the wide face (thickness) prior to grinding the narrow surface. This will assure the highest quality of the cutting edge.
    I'd agree based on the fact that most blades do have wear below the cutting edge that leaves the wide face somewhat curved near the cutting edge. If you don't get rid of that wear then the clearance at the actual cutting edge will be greater than optimum to allow for clearance as the blades bypass each other in a cut unless you grind a ton off the narrow face.

    As for shimming, are you aware of any shear which has no means to adjust the gap short of using shims?
    Most power shears do not have movable tables, so shims are required. Any fabricated steel (as opposed to cast frame) shear I've ever seen also requires shimming. Adjustable beds (tables) exist only on cast frame stomp shears, based on the half dozen various shears we currently own, and another half dozen or so we've bought and resold over the years.

    And there's one more question I meant to ask. My friend mentioned that if a HSS blade has a chip-off which is too large to be eliminated by grinding, it can be safely filled by welding prior to blade sharpening. Is it a commonly accepted method? I had my doubts (hardness change issue in HAZ), yet we know how hard the weldments are. Can you guys comment on this?
    I don't think you'll find many shears with HSS blades. High carbon, high chrome is usually an option over the standard high carbon blades. As far as I know, the optional blade material is D2 tool steel, or something close to it. My guess, based on the appearance of your shear, it would date to the 1930's at the newest, and I'd guess it most likely has just the standard high carbon blades. Assuming your blades are of the standard 4 edge variety, if I had one edge with a major chip I'd just grind it and call it a 3 edge blade rather than taking a chance on ruining the blade by welding on it. The primary difference in standard blades and the hi carbon, hi chrome variety is increased abrasion resistance. Worthwhile on a machine used daily in a working shop, but for intermittent use in a hobby shop it'd probably take 15 yrs to notice the difference unless the shear is fed a steady diet of stainless.

    Added: Mach2's advice to use a 2x6 on the pedal is a winner. Cutting at capacity with any sort of narrow pedal can leave your foot feeling like its a bird's foot wound half way around a tree limb. Been there and done it, and limped for a week.

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    MichaelP is online now Titanium
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    Each of my blades has a single cutting edge. The blades are bi-metallic: the cutting edges are formed on an inlay which is obviously made of a different alloy. I assume this is a HSS inlay. What else could it be? I don't know if the blades are original or much more modern. I'd assume that the original blades were made entirely out of a high carbon steel. But who knows... Maybe it was one of the first shears that used HSS inlays back then.
    Attached Thumbnails Attached Thumbnails blade.jpg  

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