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Whats the sharpening issue here?

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Forum topic by Nap3p posted 01-14-2021 04:10 AM 419 views 0 times favorited 10 replies Add to Favorites Watch
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Nap3p

14 posts in 158 days


01-14-2021 04:10 AM

Received a low speed bench grinder for xmas and finally got it all setup for use with a 180 grit CBN Wheel. This is my first time using a bench grinder so I took some cheap big box store Stanley chisels ($10 for 3 set) and decided to experiment on them as well as actually give them a proper setup.

Is this just an example of an irregular hollow grind from my technique? I did the primary bevel to 25 degrees (or somewhere close to that) on the bench grinder and then finished them with the MKII jig at 25 degrees on Shapton 1000/5000/8000 stones.


10 replies so far

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SMP

3187 posts in 877 days


#1 posted 01-14-2021 05:17 AM

Are you just worried about the looks? What size wheel? Did you freehand in the grinder or do you have a jig?

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LittleBlackDuck

6185 posts in 1793 days


#2 posted 01-14-2021 05:58 AM


Are you just worried about the looks?
- SMP

I always worry about my looks… that’s why I abstain from mirror finishes on my chisels.

A low speed grinder without a jig is like a car without a steering wheel.

Why did I walk into that wall?
  • too much vino?
  • not enough vino?
  • broken flip flops?
  • ball and chain around my ankles?
  • socks across polished floor boards?
  • dog across my path?

We… well I… need a tad more info to get the full picture or give me time to do a psycho course… (oops, I meant psychic).

-- If your first cut is too short... Take the second cut from the longer end... LBD

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AESamuel

111 posts in 2194 days


#3 posted 01-14-2021 10:31 AM


Received a low speed bench grinder for xmas and finally got it all setup for use with a 180 grit CBN Wheel. This is my first time using a bench grinder so I took some cheap big box store Stanley chisels ($10 for 3 set) and decided to experiment on them as well as actually give them a proper setup.

Is this just an example of an irregular hollow grind from my technique? I did the primary bevel to 25 degrees (or somewhere close to that) on the bench grinder and then finished them with the MKII jig at 25 degrees on Shapton 1000/5000/8000 stones.

- Nap3p

The grind does look uneven, and the polished bevels look huge seeing as it’s just been freshly ground. I’d expect them to be pretty tiny.
What tool rest are you using on the grinder? If you’re not using a rest that holds the tool at a fixed angle then doing it “free hand” without a lot of practise can yield pretty wild results. You don’t need a jig that holds the tool square, just a rest that’s set to the angle you’re after.

Here’s a good video describing the process: https://www.youtube.com/watch?v=GB-Pa73Snp4

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Kirk650

709 posts in 1720 days


#4 posted 01-14-2021 02:01 PM

Veritable has a bench grinder rest that will allow fixed angle (straight across) grinding. I can’t do chisel and plane blades without it.

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chriscarter

31 posts in 1063 days


#5 posted 01-14-2021 02:06 PM

I’m assuming that the edge is a true 90deg. If that’s the case, then you just weren’t even handed on the grinder when you slide the chisel across (when the iron is wider than the grinder). It’s a common problem. As you are grinding, keep checking after each pass. If it’s a little heavy on the right, then on the next pass go a little slower on the left to even it up. Almost nobody is capable of a perfectly even grind all the way across over many passes. We all check and do a little refining of the grind to make sure it’s even.

It’s also possible that your wheel isn’t true. You do have to dress them occasionally unless they are of the CBN variety. It’s also possible that your grind was even but then when you sharpened the edge you were uneven. But the first issue I stated is common, particularly when you are new to grinding bevels.

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Lazyman

6339 posts in 2359 days


#6 posted 01-14-2021 02:19 PM

Cheap chisels are notoriously non-uniform. They might not be a consistent thickness from side to side for example and the sides are often not parallel so if you use one side to square up the edge it may look wonky. All of these irregularities can contribute to an irregular grind like that. As long you have flattened about an inch of the back and the edge is sharp, you are good to go.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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higtron

268 posts in 3649 days


#7 posted 01-14-2021 02:40 PM

The wheel that ground the original hollow grind on that chisel is a different dia. than the dia. of your grinding wheel.

-- A friend will help you move, a good friend will help you move a body

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Mosquito

10687 posts in 3264 days


#8 posted 01-14-2021 02:49 PM

I agree with Chris Carter, it’s probably just your grinding that needs more trial and error if you’re free-handing. The edge looks fine after you honed it, so I wouldn’t worry about it. If it bothers you, you could either keep practicing free-hand grinding, pick up some sort of grinding jig, or just use your sharpening jig on your coarsest stones to just make the bevel with your MKII honing guide to clean it up, then adjust the angle for your final honing

-- Mos - Twin Cities, MN - http://www.youtube.com/MosquitoMods - http://www.TheModsquito.com

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Robert

4304 posts in 2453 days


#9 posted 01-14-2021 03:02 PM

Yeah, its technique. It happens to me when I’m not paying attention, even with a Veritas grinder jig.

Start out by reaffirming your tool rest is exactly parallel to the face of the wheel. If its not you’ll take uneven amounts off. Plus, you have to keep the chisel path exactly parallel to the stone face as you’re moving it.

This can happen if you lift off too soon, uneven pressure, or the rest isn’t lined up right.

-- Everything is a prototype thats why its one of a kind!!

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Nap3p

14 posts in 158 days


#10 posted 01-14-2021 04:16 PM

Thanks all. I appreciate the input. The edge is nice and sharp and I’m not concerned with looks. Just looking for a couple pointers related to technique.

I used the kodiak platform and the wheel is CBN from Ken Rizza. It doesn’t surprise me at all that I wasn’t completely square and even with each pass. I could likely have kept going to make a bigger hollow as well.

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