Setting blade clearance on a 36" foot shear

[Wray Schelin]

Does anyone have a manual or an idea what the clearances would be for
adjusting the blades on an old Niagra 36" shear? Also what would the capacity be for this shear? It seems to only want to go half way across a 30" piece of 20 gage. The blade appears to be sharp or was supposed have been sharpened.

thanks,
Larry

[Wray Schelin]

Hi Larry,

You will find that for a 36" foot shear .004" to .006" clearance range will work fine. Most 36" foot powered shears are rated at 16 gage . That means that you should be able to make a 36" full cut in 16 gage steel. If you have the blade set too tight it will bind and gall. If it is too loose it will roll the edge of the sheetmetal over. Both conditions , too tight and too loose, are not good for the health of the machine.

Before you try to set the clearance you should first tighten the gibs of the shear and lube them well. You shim the blade with shim stock to arrive at the right clearance. In the center region of the blade you might have to shim it a few thousands closer than at the ends where that blade is closer to the gibs. The reason for that is the movable part of the shear will bow out in the middle when cutting so you have to compensate with more shims. To do the job right it takes a little while and you have to be patient checking your measurements over and over till it is right.

On large heavy duty mechanical and hydraulic shears ,they often have a blade clearance setting function so you can dail in the blade clearance to the thickness of plate that you are cutting.

On my 36" jump shear I installed some premium high chrome blades
that I was lucky enough to pick up at an auction . I can now cut 14 gage with the machine the full 36" . All cuts are better if you squirt the blade with WD-40 often.

Wray

[Kerry Pinkerton]

Wray, does your shear have a hold down that decends to the metal before the blade? The one I got from Dutch does not and I think that is part of my problem. The metal wants to raise on the table....

[Wray Schelin]

Hi Kerry,

Yes, all shears need a finger hold down to keep the metal level with the table. If it is not there the metal will lift up off the table acting like a lever between the shear blades.

It would not be hard to fabricate a steel version of the original hold down which is missing from your shear.

Wray

[Kerry Pinkerton]

I've thought about doing just that (fabricate, yum). I don't THINK this Niagra had a holddown. I did not see anywhere such a thing would attach. I'll take some photos tomorrow after I unload the table (makes yet another catchall place for stuff I can't find lol)

[Wray Schelin]

Hi Kerry,

On my shear the hold down attaches with just two studs.

I remember seeing your shear at Dutch's and I thight the castngs looked a lot lighter than on mine. It is possible that your shear is a light duty ( maybe 18 gage max) or maybe a paper shear.

Wray

[Pete's Metalshaping]

Originally Posted by pinkertonk

I've thought about doing just that (fabricate, yum). I don't THINK this Niagra had a holddown. I did not see anywhere such a thing would attach. I'll take some photos tomorrow after I unload the table (makes yet another catchall place for stuff I can't find lol)

Hi Kerry,

My Niagra doesn't have a hold down either. I was looking at a friends Pexto shear and it looks like a hold down similar to the Pexto would work on mine. I will try to put together a design for mine and will share it with you if you would like.

Larry