Straightening hammer weight

JoeBusic

JoeBusic

Knifemaker / Craftsman / Service Provider
Joined
Jan 21, 2020
Messages
543
What weight would be optimal? I'm making one. Asked in the closest machine shop for broken carbide bits and got a handful of different sizes. There is a 6mm, 30mm long, ideal to drill a hammer and fit. But there are chunks from 16mm bits. So I'm wondering if it's useful as is, just add a handle.
 
Not sure what weight is optimal, but I bought a 16oz and it works great. Just a couple tips that I didn't think of, so my carbide bit is slightly off center.

1. Grind a small flat spot on the tip of the ball peen end as centered/square as you can
2. Use a center punch to keep the drill bit from walking
 
I found I like the 7oz weight it’s not too heavy or too light and a 3/8” ball leaves a less noticeable divot than a smaller diameter. Be careful using a drill bit to shape a nice round face to use for the actually pein, I wouldn’t use them as is, the sharp point can be more stressful and you could run into more issues with cracking a blade. I’ve straightened a few thousand knives with a rounded tip for the carbide and not had any issues with cracking a blade but I know traditional straightening hammers in Japan where the idea comes from use a chisel and I believe you have to be much more careful/mindful with that style of hammer. I’d look for a bit as close to 3/8” as possible and fully round and polish the striking end. Just as an example here’s a photo of the hammers I make.IMG_8743.jpeg
 
I have a bunch of broken bits, so I'll grind some to see how it goes. If it's workable, a thicker bit will be used. If very hard, then a 6mm will be used. There is one 16mm with 160g (5.5oz). I'm thinking will it be enough as is and just add a handle. All are full body carbide, so the butt is simplest to round.
 
It's a bitch to grind. Big one is laughing to my face. 6mm it is :cool:
Have rounded it to approx 20mm radius.
 
One more question. Is there a threshold of hardness and carbide size and amount when straightening becomes too dangerous?
 
Natlek said:
What you use to grind TC ?
Click to expand...
Normal ceramic. 120 grit at the highest speed on the grinder and the bit was rotating at high speed counter direction. Belt is history in 1min. Grinding is impossible, but scratching is possible. So make millions of them! :D
From a broken 3mm bit I made a precision center punch.
 
JoeBusic said:
One more question. Is there a threshold of hardness and carbide size and amount when straightening becomes too dangerous?
Click to expand...
I have had a couple mishaps when straightening when I was using a carbide bit for peening. The bit was smaller in diameter and no perfectly round so peening divots were deeper. I popped a huge chunk out of the spine on a Cruwear kitchen knife, besides the carbide bit issue I mentioned above the shop temp was 19F which in hindsight was probaly not ideal.

I also broke an AEBL blank using the same hammer. That time I think issue was I struck on the edge of the spine.

Since buying a hammer from Joshua I have had zero issue. Between the 3/8 carbide ball and being more aware of where I am striking all has been good even straightening some 10v blanks that were at 65 Rc.
 
Seedy Lot said:
Since buying a hammer from Joshua I have had zero issue. Between the 3/8 carbide ball and being more aware of where I am striking all has been good even straightening some 10v blanks that were at 65 Rc.
Click to expand...
This is excellent info. Thanks, man.
 
JoeBusic said:
Normal ceramic. 120 grit at the highest speed on the grinder and the bit was rotating at high speed counter direction. Belt is history in 1min. Grinding is impossible, but scratching is possible. So make millions of them! :D
From a broken 3mm bit I made a precision center punch.
Click to expand...
Well , good luck with ceramic belts on TC :) Diamonds , you need diamonds for that sh** .
This one are 16mm. Dia . Plan was to make hammer for straightening but then I try this 30mm ball from ball bearing and it works flawless .................. You can *see* where it hit but there is no dent . So I never make that TC hammer .Now I wonder why it must be tungsten carbide , hardness or weight matters or both ?

wYTbDbf.jpg


One of this will do job on Dremel

quIQtni.jpg
 
I think the purpose of TC is the hardness so it doesn't change shape as the peening progresses. The larger diameter (3/8" ball) works better since it's a larger diameter pivot "dents" that cause the straightening to happen.
 
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