How do you sharpen a 4' sheetmetal shear?

I've got a Pexto 137-L7 4' sheetmetal shear at school that's duller than a butter knife. there is a 3" spot right in the middle that will still cut, and even then it's more likley to fold the metal over instead of cut. it even has trouble with brass and copper if the piece is to wide. So, how do I sharpen it? Can I put valve lapping compound on it like a reel type lawn mower? Can I adjust the blades closer together? Or do I have to take the blades completely out(which I'd rather not do)? Thanks

-Jeff

 

I am afraid you have to pull the blades. Not 100 percent sure but I will go and ask the sheetmetal supervisor.

 

If they aint adjustable,you may have to take them out,give them some dressup(grinding),and shim them correctly when you put them back in.
Boring work,but it will be worth it!

 

sounds like you're either gonna have to replace the blade, or send them out for grinding, you might get lucky and have a better edge to use yet, they're generally made with 4 cutting edges, so you can flip/rotate to a new edge.

 

I have also found that when some guys think its dull they are just WEAK! They call it a stomp shear, line up your work, step up with one foot, and with one smooth movement bring up the other foot and throw yourself down with all the force you have! The two young guys here cant make ours go through 20 Guage while I can cut 16G with ease.

 

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sounds like you're either gonna have to replace the blade, or send them out for grinding, you might get lucky and have a better edge to use yet, they're generally made with 4 cutting edges, so you can flip/rotate to a new edge.

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jeff

this is correct.. you can usually flip the lower blade over and have a fresh side..

I have the same shear here at school as well.. (must be every school shop was outfitted with one...) anyhow another tip is to make sure the machine isnt rocking around all over the floor and that some stupid kid didnt loosen any of the chassis bolts.. (i had that happen my 2nd year teaching) these bolts will allow the legs and the table to move around and may cause your alignment to change

good luck sawzall

 

I just bought a used Tennsmith 4' shear and I flipped the blades, seems to work fine.

 

Thanks for the info. With a real good stomp, it will cut brass and copper, but even with heavier perple, a preloaded jump won't cut steel. I'll try flipping the blades around. Knowing the guy I replaced, it's probably never been serviced and is still on the two origional edges.

When I re-adjust it, should the blades be touching like a scissors, or should there be a few thousandths gap in between them?

-Jeff

 

Sawzall is right,you should be able to flip the blade.

When you pull the blade out,you might find it has been counterbored on both sides,
which means you have 4 usable edges.

I think they get set up to JUST touch,if your doing thinner material.
There should be someway of adjusting the blade position without resorting to shims.

 

It can, be big $$$$$$ to get them sharpened FWIW

 

If you have them sharpened, be sure to send them to a place with experience with shear blades. I used to teach an HVAC Vo-Tech class. The Director had the Machine Shop class grind ours and it came back screwed-up.

 

"When I re-adjust it, should the blades be touching like a scissors, or should there be a few thousandths gap in between them?"

Hi Jeff, You need to have clearance between your knives. A good rule of thumb is 10% of the thickness you're cutting.
For example , if you cut mostly 16 gage , you should have around .005 to .006 clearance. I cut mostly 20 gage and occasionally 18 and 16 gage, so I set mine at .004. Make sure that your clearance's are the same all the way across. If not , you will have to shim up the loose spot. Bill

 

Here is one place that does sharpening and sells new blades. www.federalknife.com

 

Some of those blades are ground on both sides.... if so try flipping it over!

 

You found a four year old post, and give the same response as twelve other guys did?

And I just brought it to the top again? On tech week even? Who's dumber, you or me?

 

Hold the treadle down, and then adjust the blades. They shoud be tight enough that the treadle will still move without the blades dragging.

If you have too large a gap it will still shear but will leave a very sharp edge 90 degrees from the surface or it will fold the sheet.

 

belt sander?

 

you need the blade reground if possable or a new blade, you need to go to a industrial supplier of shear blades name below> it is not going to be cheap probalyl $600 to$1000 maybe less??? it is a smaller blade and a recession year and you might be able to ups. but plan on truck ship and plan to pay in advance since your a private person not a company

asko blade company
Preston Dennis
Manager of Operations & Regrind Sales
Phone: 708-339-1350
Fax: 708-339-3757
Email: [email protected]

 

Hopefully, after 4 yrs., he got it figured out. But, I've changed out, flipped and adjusted blades on a 10', 5/8 cap. multi ton hyd. shear many times. The blades need to be ground and it ain't cheap, about half the price of new ones. We use to send them to a outfit that, mainly, sharpened blades for the paper industry, where they cut huge stacks of paper. They didn't like grinding them down below a minimum width without legal disclaimers and such but I doubt that would be a problem on a little shear though.

 

Well here I go in to the archives of the HAMB, I just bought a used Tennsmith 52" stomp shear off craigslist and without thinking I did not take a scrap piece of metal and, well you get it, I got home and unloaded the machine and promtly found out that I had not bought a shear but a break! Well at least that is what it does currently! So today I will get it apart, clean it and check the edges and maybe reverse the cutting blades as I read here, and shim to specs provided here. Any other advice you can offer would be helpful.

 

Good luck on your adventure oldguard
Well the blades should have 4 sides and can be turned that many times before re sharpening is needed. No telling how many times they have been turned before you got it. There's adjustments , there's also bushings that wear.
If the bushings are worn then no amount of adjustment is going to help and may actually cause damage if altered beyond the range.
Problem with the bushings is you usually need to disassemble the whole thing to change them. I'd see if you can download a manual from tensmith

 

One day I found my foot shear with a broken cast iron step. No one knew anything about it.

A few years later, I found a piece of 1/8' plate that was severly chewed up on a foot shear, hidden way in the back room.

Mystry of the broken step solved.

I think that it was the same person that tryed to clamp down a piece in my break and snaped the cast iron handle and adj. bracket! (no one knew about that either!)

 

wait, before you get around to working on it, do you think you can bend up some stuff for me.

 

pretty nice craigslist find!

 

That brake looks familiar .. Okc CL!?!.. I wanted to drive up and look at that one. Glad a HAMBER got it .. Good luck with the blade hope it works out for you. John


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I never knew the blades could often be swapped around. My 4' McCullough cast shear is juuuuust starting to drag a little so I'll check it out.It's a big heavy sucker tho..

 

Working in a scrapyard I get lots of experience with shear blades. I've even taken night classes at a tech school to use their surface grinder. I always try to shim to 0 clearance on all of our shears. We have a 1200 ton shear that I shim to 0 clearance.

 

https://www.google.com/search?sourc...87,d.cGE&fp=daa1945f706079e5&biw=1440&bih=703
Link to Google search, might contain some info you can use.

 

Went out to the shop today and started cleaning the shear. I was glad to find out most of the finish was covered in a thick grease and it cleans off with PB Blaster and rags and steel wool. The finish is sun faded but responding. After further examination and reading several links including a factory Tinnsmith information page, I have determined that the factory blade can be flipped over for a second cut and the ratio is two tops to one bottom. The factory charges around $100.00 a side and there 2 on the top and one on the bottom, so around $300.00 plus the ride. This one has not been flipped so I will tr that and reset the clearances as described in the factory link. Thanks for all the help and tips, will report back soon.

https://www.pts-tools.com/MSDS/PK5052.pdf

 

The price information I got before was a independent and Tennsmith said to do the machine work was around $200.00 for both blades, or $600.00 for both new.