Author Topic: Curved scissors  (Read 112 times)

Offline RickKrung

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Curved scissors
« on: October 27, 2020, 03:41:23 pm »
I have been presented with a set of curved scissors for sharpening.  These particular ones are "grooming" of a sort - clipping the hair/fur from cow's ears around the ID tags so the tags can be seen more easily.  While both blades have large curves, the bevel on one blade is relatively straight, whereas the bevel on the other blade is convex. 

There was a previous thread here on curved scissors, but it did not provide much useful information.

The curvature on these is so great, I am not sure how to clamp them in the scissors jig.  Haven't tried anything yet, but I'll work on that.  Assuming I can figure a way to hold them, I think the first blade, even though it isn't perfectly straight can be sharpened in the conventional manner.  I think doing so may enforce a flatter/straighter bevel. 

I am thinking that for the convex blade, the scissors jig will need to be rotated/rocked to pass over the entire bevel, somewhat like free-handing, but with the jig maintaining the bevel angle.

A curious feature on the bevels of these blades is that the grind marks/lines are parallel with the blades, rather than perpendicular. I have wondered about using my Viel belt grinder to work these bevels to keep the grinding pattern parallel, but have not yet sat down with it to see how that might be done.  Owners were clueless about any and all of this. 

First issue I have to solve on the Viel is that the motor has stopped working (PSI variable speed/reversible).  Comments on the FB Viel site said that it could be grinding grit that has gotten into the electronic and that simply blowing it all out remedies the situation. 

I'm interested in hearing ideas on how to sharpen these.  These are not high end scissors, by any means, but I sure don't want to mess them up, as these folks need them to work and who knows if they can be replaced. 

Thanks,

Rick
Quality is like buying oats.  If you want nice clean, fresh oats, you must pay a fair price. However, if you can be satisfied with oats that have already been through the horse, that comes at a lower price.

Offline cbwx34

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Re: Curved scissors
« Reply #1 on: October 27, 2020, 04:25:05 pm »
That is a specific use.  ;)

I'm not sure if they're really going to be as difficult as they initially look.  I'd be suspicious of the parallel grind marks, wondering if it was done as a way to maintain them?  Some instructions recommend honing parallel to maintain the edge on scissors, probably because it's easier.

If possible, I'd see if I could find a new pair online to at least look at to see.  But if it were me, I'd sharpen them perpendicular to the edge on either the Tormek or Viel, (whichever works better matching/following the bevel) matching the current angle, debur as SteveB suggests in this thread, (as well as his other tips)... and see what the customer thinks.

Offline Elden

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Re: Curved scissors
« Reply #2 on: October 28, 2020, 02:30:22 am »
I would imagine the Twice As Sharp style machine would be a little more easily utilized. The grinding would be perpendicular to the blades as mentioned above.
Elden

Offline RickKrung

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Re: Curved scissors
« Reply #3 on: October 28, 2020, 02:57:23 pm »
Easy Peasy. So easy, I'm almost embarased to have have asked anything about them.  The blades clamped far more securely than I expected and perhaps because of the heft of the blades, there was no vibration or chatter.  Took a lot of grinding to get even close to a burr. 

Rick
Quality is like buying oats.  If you want nice clean, fresh oats, you must pay a fair price. However, if you can be satisfied with oats that have already been through the horse, that comes at a lower price.

Offline cbwx34

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Re: Curved scissors
« Reply #4 on: October 29, 2020, 02:42:11 pm »
Easy Peasy. So easy, I'm almost embarased to have have asked anything about them.  The blades clamped far more securely than I expected and perhaps because of the heft of the blades, there was no vibration or chatter.  Took a lot of grinding to get even close to a burr. 

Rick

No after picture?   :o

(Hopefully, you warned them not to take off an ear!) 

Offline RickKrung

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Re: Curved scissors
« Reply #5 on: October 29, 2020, 05:33:40 pm »
No after picture?   :o

(Hopefully, you warned them not to take off an ear!)

 8) Yes, a bit anti-climactic perhaps, but no after pix.  I didn't provide any pre-pix of the bevels.  After-pix would have only shown the nominal perpendicular grind pattern, so I felt there was no benefit to them.

I initially sharpened both blades with the 80 grit Norton 3X grindstone that I use for roughing and re-establishing  bevels and leaving them with the very toothy finish so as to grab the coarse cow-ear hair/fur.  I left the the thumb blade (lower, if held in the right hand with the curved blades going from center-to-left - couterclockwise) with that grind finish.  I added a bit of a micro-bevel to the upper blade using the DF and DE Tormek diamond wheels to put on a more refined apex, to serve as more of a cutting/slicing edge.  It turned into more than a micro-bevel than I planned, but I was not concerned about it. 

I did NOT caution them about taking off part of ears, for two reasons: 1) these are ranchers - they know better than I about stuff like this, and 2) I don't know them well enough (read "at all" - having never met them before) to make that sort of comment.  They'll figure it out pretty quick and if they do lop of some ear, it will be very minor compared to what else they subject these animals to. 

I would like to hear back from them how well the scissors work, but doubt I will.

This tiny little, very rural and secluded valley just turned its first two Covid-19 cases - youth pastor and his wife at one of the local churches .  Most of the stores and services and the school are now closed due to how many have had to go into quarantine.  Big shock to so many who thought it was all a scam.  Just a matter of time, however, in my view.

Rick
Quality is like buying oats.  If you want nice clean, fresh oats, you must pay a fair price. However, if you can be satisfied with oats that have already been through the horse, that comes at a lower price.

Offline cbwx34

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Re: Curved scissors
« Reply #6 on: October 29, 2020, 05:59:43 pm »
...
I did NOT caution them about taking off part of ears, for two reasons: 1) these are ranchers - they know better than I about stuff like this, and 2) I don't know them well enough (read "at all" - having never met them before) to make that sort of comment.  They'll figure it out pretty quick and if they do lop of some ear, it will be very minor compared to what else they subject these animals to. 
...

Sorta kidding about the ears... but I always warn people I sharpen for that... this knife/scissor/etc. will not perform like you're use to.  Give someone a knife that hasn't been sharpened since they bought it 20 years ago... I can almost guarantee they'll cut themselves without being warned... (and probably even if they are).  :o

Offline RickKrung

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Re: Curved scissors
« Reply #7 on: Yesterday at 01:47:15 am »
Sorta kidding about the ears... but I always warn people I sharpen for that... this knife/scissor/etc. will not perform like you're use to.  Give someone a knife that hasn't been sharpened since they bought it 20 years ago... I can almost guarantee they'll cut themselves without being warned... (and probably even if they are).  :o

I figured it was kidding.  I often do warn people when I've sharpened knives for them, as they are way sharper than nearly everyone has ever seen on a knife.  Not nearly so much with scissors, although some have actually been sharp enough to warrant warning.  For example, a local woman grows hemp, for the fiber and the CBD.  She recently brought a ton of Felco clippers and some funky little, curved nipper scissors that they use for clipping the leaves, or something.  Those were sharp enough and her workers not likely to be used to them that way, so I did warn her.  Payment was in the form of several dropper bottles of CBD oil :D

Just didn't feel the need this time. 

Rick
Quality is like buying oats.  If you want nice clean, fresh oats, you must pay a fair price. However, if you can be satisfied with oats that have already been through the horse, that comes at a lower price.