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Reground Rada Cutlery

Posted by me2 
me2
Reground Rada Cutlery
May 08, 2016 06:45PM
I finally got around to regrinding the Rada Santoku that has been my guinea pig knife for some time now. I long ago ground away the original hollow ground edge. This was an attempt to get it back in service while also experimenting with some regrinding.

I set the primary bevel at about 3 degrees per side with a 40 grit belt, then ground until just a hint of the original 12 dps edge bevel was visible. I did not take it to a burr with the 40 grit. It was previously at about 6 dps, as a first step in regrinding it. That bevel was completely removed. The current bevel is about 5/16" wide, on 1/32" stock. These knives are extremely thin.

I then sharpened it at somewhere in the 7 to 10 dps range. The edge bevel width is less than the thickness of a playing card. Even after heavy destressing on a tile rubbing stone, it only took 35 passes per side to raise a large burr on the Norton 220 grit water stone, which was then cut off using the 1000 grit King and an angle increase of about 2 degrees. Then to the Sharpmaker Mediums at the same angle, then some deburring passes at about 30 dps, then more medium, then fine. There is a section toward the tip that is a little duller than the rest, about 2 inches long. I'm going to leave it as is for a while. When the grinding was done, but before the sharpening, flexing the edge over my thumbnail produced visible deformation, some of which stayed. This appears to have been removed by the sharpening though.

I plan to make some knives like this from some older recycled blades, so this is an experiment to see how low I can go. I have some larger blades that have outlived their usefulness in their current form, so I figured I'd reshape them. One is a large machete who's handles are just awful, but which appears to have very good steel. The others are some kitchen knives that are in need of reshaping and regrinding, so I might as well rehandle too.

On another note, anyone got any advice for 1x30 grinding belts for this? The Harbor Freight 40 grit belts are only good for about 1 side of a knife this size. There have to be some out there that last longer. On the other hand, they're only $1.50 each, so it might not be worth it.
Re: Reground Rada Cutlery
May 08, 2016 09:00PM
Have you tried the Norton Blaze or equivalent? You can get them for 1x30" . As with any belts, if you use a lubricant they will last significantly longer.

The Herder's are ground like that. They readily flex over the thumbnail.
Re: Reground Rada Cutlery
May 09, 2016 02:10AM
Those Norton Blaze belts, though expensive, remove a lot of metal fast (removes flesh even faster smiling smiley ).

A tip I can share.

Buy a diamond dressing wheel and dress the edges of the belt when new. This will prevent those slight inconsistencies that are normally on the edges of belts. You can also dress the belt from time to time. This will extend its life as well.
me2
Re: Reground Rada Cutlery
May 09, 2016 04:08AM
How is the Herder for things like cutting up an apple? This thing takes quite a bit of effort, leading to the edge smacking the cutting board regularly.
Re: Reground Rada Cutlery
May 10, 2016 07:27PM
I'll get a few apples and measure a force. It will be minimal given the geometry.
me2
Re: Reground Rada Cutlery
May 11, 2016 02:14PM
It seems a case where a more obtuse geometry would produce a splitting action and make cutting easier.
JDW
Re: Reground Rada Cutlery
May 12, 2016 12:41AM
My parent use theirs for cutting apples all the time. I have used it for that task too. Great knife for cutting food.
Re: Reground Rada Cutlery
May 30, 2016 06:34AM
When we had some repairs done to our roof the roofing guy was using an old Rada as a work knife and left it behind. The tip is all mangled and bent but I plan on fixing it up in the near future. The edge retention on them isn't stunning, but when kept sharp they do a decent enough job cutting food as intended. Don't think it fared as well on shingles! grinning smiley
me2
Re: Reground Rada Cutlery
May 31, 2016 07:58AM
Can you elaborate on the less than "stunning" edge retention? I'm learning that people say things like that and have a good idea what they mean, but no one else does. It leads to a lot of confusion sometimes.
Re: Reground Rada Cutlery
May 31, 2016 09:04AM
Chris,
This inspired me to thin out one of the zero-grind $0.99 paring knives I have. I got it down to 0.005" with the TASK by hand. I really can't see getting it any thinner without the steel crumbling, it has a pretty poor HT. Cuts very well, however.

"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
me2
Re: Reground Rada Cutlery
May 31, 2016 10:01AM
I need to use this knife more. I have been favoring the tojiro lately but need to pick the RADA back up. I cut a couple hundred feet of cardboard with it and the edge was undamaged. Dull, but undamaged. Nice for such a minimal geometry.
Re: Reground Rada Cutlery
May 31, 2016 11:14AM
Chris,
I don't really see the need for thick grinds or +30dps angles on the edges for these types of knives. The thin ones with <30┬░dps (less than) angles are a joy to use. They don't dull any faster either.

"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
me2
Re: Reground Rada Cutlery
May 31, 2016 07:33PM
I was moderately surprised, as the cardboard I use has some glue on the outside at times and I thought that might roll the edge, but its still fine. It will shave my arm with a lot of pressure, too much to risk cutting myself. I'm betting it will resharpen with about 10 pps on my 1k King stone. Naturally I'll follow up with some medium and fine sharpmaker passes for refinement.
Re: Reground Rada Cutlery
June 01, 2016 03:23AM
The King 1k and Sharpmaker or its rods are a awesome combination. Makes it almost foolproof to get a super sharpe edge.

"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
me2
Re: Reground Rada Cutlery
September 27, 2017 12:15PM
Just an update. I have this one away with a batch of knives l reshaped for the church where my wife works. They should get way more use than me out of it.
Re: Reground Rada Cutlery
November 01, 2017 08:44AM
recommended the Rada santoku/chef's knife in a food forum. I think most users are shocked the first time they use one of these feather lite knives and see how well they cut. currently you can get both Rada santoku shaped knives for less than $30 delivered. If users can just get by the idea that it doesn't have to be Master Baka's Rimbyo to be a usable kitchen tool.

scott
[www.etsy.com]
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