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-   -   "Adjusting" shear blades (http://talk.craftweb.com/showthread.php?t=11760)

Travis Frink 10-31-2017 10:21 AM

"Adjusting" shear blades
 
I got a new pair of Maruko diamond shears as a thanks for a couple cherry wood blocks I made for a friend with the rather ambiguous caveat that said shears need to be "customized to cut right". And they don't (I'm spoiled after using Carlo Dona shears). The blades don't meet right and significant sideways force is needed to get them to meet and cut right.

My question: Is there a "proper" or better way to bend or cold forge shear blades so they meet and thus cut right? They are thin. What should be the focal point? Hammer? Mallet? Bench Vice? Don't even try?

Thanks for any advice

Rich Samuel 10-31-2017 11:57 AM

Did you possibly get a prototype? ( https://www.reddit.com/r/glassblowin..._cutting_edge/ )

Travis Frink 10-31-2017 06:32 PM

Could be. I don't know. Sounds like the same problem I'm having. I'd just like to get them to cut better. They are the coolest looking diamond shears I have but I'm not much for using tools as decorations.

Scott Dunahee 10-31-2017 07:50 PM

I have sent tools to Jim Moore to be tuned up before. He did a remarkable job with some old esemce (sp?) shears I had.

Just an idea.

BSD

Eben Horton 10-31-2017 09:06 PM

Take them apart.. one side has threads for the bolt that holds them together, and the other side doesn't have threads. take an open end socket and tighten that bolt so that the shears feel tight, but not too tight. Then without moving the bolt, thread on the nut and with one hand on the wrench that is holding the bolt, take another wrench and crank down on the nut so that the nut compresses against the side of the shear. if you move that bolt at all, you will throw off the tuning you just did.

Travis Frink 10-31-2017 10:39 PM

Quote:

Originally Posted by Eben Horton (Post 137172)
Take them apart...

I tried that. The blades don't meet without significant sideways pressure while cutting. The blades look like they need to be bent slightly to meet properly.

If Jim Moore was closer, I might ask him. Then again I kind of like the idea of learning and then being able to maintain my of tools.

Eben Horton 10-31-2017 11:11 PM

Quote:

Originally Posted by Travis Frink (Post 137173)
I tried that. The blades don't meet without significant sideways pressure while cutting. The blades look like they need to be bent slightly to meet properly.

If Jim Moore was closer, I might ask him. Then again I kind of like the idea of learning and then being able to maintain my of tools.

Oh. Hmmmm. Send them to Shin and tell him that they are defective.

Mike McCain 11-01-2017 12:33 AM

Quote:

Originally Posted by Eben Horton (Post 137174)
Oh. Hmmmm. Send them to Shin and tell him that they are defective.

Or maybe take a flight, deliver them in person and learn about show/how. If you care that much about having them fixed, and that much more about knowing the process, I'd say go to the source.

Jordan Kube 11-01-2017 12:34 PM

We had Jim come and give us a little refurbishment demo a couple of years ago. I would rather see the exact problem with the shears before I give out advice so take this with a grain of salt. To get the blades closer to touch, he would get some sort bolt or pin that would center in the hole and support the rest of the shear underneath. He would then take a mallet to the shear to bend the blade end in with the hole being the point form which the shear bent towards itself. You could probably just clamp it down at that point really good too and give it some taps with the same effect. I hope that makes sense. It's a go slow operation. Take your time.

Sky Campbell 11-01-2017 01:41 PM

I have similar advice as Jordan. I would clamp them in a vise at the pivot point and gently tap them in. Rinse repeat. Do not grind or file the mating surfaces that is the one thing that makes repair almost impossible. If they are not flat at the mating surfaces you can lay them on the anvil or flat anvil like object with the flat surface towards the anvil several taps should lay them flat to the anvil.

It is really hard to understand the problem so any advice without seeing what the problem is could do more harm then good. Do not hammer on the mating surface of the shear.

Travis Frink 11-01-2017 10:32 PM

Quote:

Originally Posted by Mike McCain (Post 137176)
Or maybe take a flight, deliver them in person and learn about show/how. If you care that much about having them fixed, and that much more about knowing the process, I'd say go to the source.

There's a roadtrip in that direction in the unforeseen future. They also did come from the source in need of modification and are not the first pair in need of either. They were a gift so I can't complain.

Travis Frink 11-01-2017 10:55 PM

Thank you Jordan and Sky

I took apart my Moore and CD shears and learned that the inside faces of the blades are "Wavy" with the high points being the inside of the pivot bolt hole and the V of the cut. When the CD shears are closed the two blades touch at the bolt hole and the v of the cut. When the CD shears are closed, there is about .5mm space between the blades between the bolt and cut and a 1-1.5mm gap at the shear tips where you would hold a pipe or punty rod. The Moore shears have less gap but have always cut fine. The CD shears cut cleanest. The Maruko shears in question don't have anywhere near the same contour definition ont the inside face (very little contour actually) so I guess working to get the inside blade faces to resemble the other two types (which cut properly) is the best place to start.

The blades are also really thin and they bow quite easily so I'm thinking it might be a necessary over exaggerate the contours a little to compensated for the flex of the thin blades. I'll do it a little bit at a time and check how they cut little by little. Now to find a vice to borrow.

If nothing else, my Jim Moore shears should now cut real well as I sharpened them while they were taken apart.

Max Grossman 11-02-2017 09:46 AM

Be careful doing things cold! You don't know what kind of steel he used or how he hardened it, so you might crack em!

Whenever I adjust antique tools, especially if they were hand forged, I use heat. Brazing torch, and hammer down over an open vise or swage block to bend it - using a wood hammer if I don't wanna put hammer marks. Depending on if I'm adjusting a handle or a shear blade, I re-quench and re-temper, or just leave it alone. It's a judgement call if that part needs to be hard or soft.

Remember, shear blades are slightly curved and should meet strongly at the tips. Most diamonds are flat and hollow ground so they meet in the middle.

Get in touch with Jim if you want more advice, he's a great guy!

Travis Frink 11-03-2017 07:51 PM

Quote:

Originally Posted by Max Grossman (Post 137190)
Be careful doing things cold! You don't know what kind of steel he used or how he hardened it, so you might crack em !

Thank you for the advice. I was worried about this as well. There is a lot of flex in the blades. Don't know what that means but guessing the steel is soft not hardened that much?

The thought of ruining a beautiful tool (even if it doesn't work so well) makes me reluctant to continue without really knowing what I'm doing. This might have to wait til I can make a trip to a tool maker or am emboldened by adult beverages and a sense of adventure.

Rich Samuel 11-04-2017 12:19 AM

Quote:

Originally Posted by Travis Frink (Post 137203)
There is a lot of flex in the blades.

That alone doesn't bode well. Possible eBay "bargain" from China?

Pete VanderLaan 11-04-2017 08:22 AM

why does dipping hot steel in oil harden the steel?
Why does it mess it up if you do it too many times.

What kind of oil?
I have been fascinated by the programming on cable issuing challenges to blacksmiths to make specific items, like sword blades in three hours.

Mark Rosenbaum 11-04-2017 09:36 AM

Quote:

Originally Posted by Pete VanderLaan (Post 137205)
why does dipping hot steel in oil harden the steel?
Why does it mess it up if you do it too many times.

What kind of oil?
I have been fascinated by the programming on cable issuing challenges to blacksmiths to make specific items, like sword blades in three hours.

I love Forged in Fire!!!

Randy Kaltenbach 11-04-2017 11:17 AM

Quote:

Originally Posted by Mark Rosenbaum (Post 137207)
I love Forged in Fire!!!

Oh yeah! +1

Greg Vriethoff 11-04-2017 11:37 AM

Quote:

Originally Posted by Randy Kaltenbach (Post 137209)
Oh yeah! +1

I got sucked into binge watching that program one day. My wife and I don't have cable, so I can only watch stuff like that at other people's houses.

I also found it to be quite enjoyable.

Greg Vriethoff 11-04-2017 11:41 AM

Quote:

Originally Posted by Pete VanderLaan (Post 137205)
What kind of oil?

Various kinds. Hobbyists tend to use motor oil. It's a cheap, readily available source.

Max Grossman 11-07-2017 12:51 PM

Quote:

Originally Posted by Pete VanderLaan (Post 137205)
why does dipping hot steel in oil harden the steel?
Why does it mess it up if you do it too many times.

What kind of oil?
I have been fascinated by the programming on cable issuing challenges to blacksmiths to make specific items, like sword blades in three hours.

When ya quench it, you cool the outside rapidly - think prince rupert's drops. then you temper it (aka anneal it) to get a bit of the stress out of the metal so it doesnt crack.

Some things are selectively hardened - say the blade of a stone cutting chisel is hard to cut through rock, but the end where you strike with a hammer has been tempered (softened) so it doesn't break from the hammer blows.

I've been playing with some air hardened steel to make jack blades, shear blades, and tweezer tips - it self hardens as it cools, which is better for the business end of glass tools since you lose the hardening when you overheat the tools.

to the OP - I would send it back to Shin, and tell him what's going on. If I were doing it, I would heat it, bend it, then properly heat treat depending on what part of the shear. But the heat treat depends so much on what steel he used! I quench mild steel in water (barely even hardens it) but would never do that to tool steel - unless it was a water quenching steel! See what I mean? Hard to know how to treat the metal till ya know what it's made of.


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