Thread: Would adding a hand wheel to your powered grinder, to make a

Most people do not realize that CBN wheels have an optimum speed range of 15-30 m/s which works out to between 2800 to 5600 rpm on an 8" wheel.

Optimum means "most steel removed for least pressure, and lowest CBN loss".

At slower (and higher) speeds that this there is a tendency to push harder to get the CBN to grind metal so you will wear the CBN away faster.

If you want to control the amount of grind for minimal metal loss its better to use the proper speed and set up some sort of holding mechanism for the object being ground that incorporates a fine controlled feed mechanism. This is what tool and cutter grinders as used by metal workers do. The feed mechanism usually has fine pitch thread that limits how far forward the work piece can be moved.

Using a hand wheel may end up tearing out more CBN crystals than usual from the wheel.

Another option for slower metal removal is to find an old/used CBN wheel - there will remove much less metal than a new one.

Bob your answer reminds me of the joke about the irishman who was asked by a traveller for directions, and solemnly advised, "Oh if I was you, I wouldn't be starting from here!"

Yes I would be using this on a white wheel as the benefits of a CBN don't really apply for the type of fiddly work you might want to use a hand crank for.

The other main impetus for me is that my wife is now WFH because of Covid and it'd be unfair on her and the neighbours (whose living areas are fairly close to my work area) to be firing up a grinder in work hours.

IMHO, Bob's still on the right track.

Most cranked grinders are geared and while they don't reach the RPM's of a powered grinder it's still significantly faster than you can get at 1:1. I suspect that to all intents and purposes it wouldn't be that much faster than using a flat stone, but with less fine control over the cut as you'd be doing it one-handed.

There's good reason why old traditional, non-geared foot-pedalled grind stones tended to be in the 3 foot diameter range.

FWIW, I have an old hand-cranked 'un (5 x 1/2" wheel) that I still use for shaping model parts and driving a polishing mop... but it's definitely not suitable for working iron!

Off the top of my head 'tis about 1:20 gearing.

I'm pretty sure white wheels are the same - a minimum speed is needed otherwise lots of grit is lost for relatively little metal removal

Originally Posted by Cgcc

The other main impetus for me is that my wife is now WFH because of Covid and it'd be unfair on her and the neighbours (whose living areas are fairly close to my work area) to be firing up a grinder in work hours.

A decent grinder should not make that much noise especially compare to even something like a power drill. I have a very fussy neighbour over the back (His pool and entertainment area are right up against the back fence) but have no problems with running a grinder while he's entertaining. That said my CBN grinders are 3P and are super smooth.

As Skewie says perhaps a flat stone or some coarse Wet or Dry on a flat glass plate would be just as or more effective for flat or straight edges/surfaces/

As for creating a hollow on the back of a blade, for HSS this is probably a job for a profiled wheel on a specialised surface grinder.
On carbon tool steel its most likely done prior to hardening and tempering.

Hi Bob,

Yes I've noticed the CBN wheel is relatively quiet - but dread the noise a white wheel would make. I think I am a bit spooked by an obnoxious neighbour across the road who does some auto work and when he fires up his grinder the whole street can hear (I don't mind but assume the townhouse neighbours hate him with the fire of 1000 suns).

A white wheel may also be sub-par in terms of use of material at a slow speed - but who cares about wasting a bit of grit on a white wheel? They are cheap and readily available. I think I have about 3 in a drawer leftover from getting one free with purchases. Besides, the sort of small, fettling work you could do with a hand grinder won't be doing much in absolute terms.

Flattening on a plate has its limits when you're dealing with a convex edge for lengthy reasons I am experiencing dealing with a large drawer-full of vintage Bergs all with heavy bellies, and a few with pitting at the tip. I have a granite plate and pile of wet-and-dry starting with P80 (also have toyed with 36 grit for hard removal). I have lapped a number of chisels flat and it is just not efficient for removing the heavy bellies created when a predecessor has convexed the tip of the back. The technique I am following (from the Charlesworth DVD I purchased because I am a little fixated at present) also calls for having the edge protrude which cannot be done on a large plate.

My stop-gap solution today ended up fairly ugly but effective. A dremel and diamond wheel hitting the areas of the back where you would expect to see a hollow in a good Japanese chisel. At first I was a bit nervous but I found I quickly lapped out the initial, nervous, hollows I was making. If you have a thick belly on a wide chisel, lapping for 30 minutes on wet-and-dry sheets is just for the birds.

I watched a Youtube video while figuring this out - from what I can see this is done with a somewhat profiled wheel and plenty of skill.

Chris

I agree about the ALOX wheel - if you have spares go for it.

Just after I posted yesterday I also thought of a dremel

As for quickly creating a hollow, a round flap wheel in a drill night work.
They come in different sizes and grits.
Screen Shot 2022-01-13 at 6.04.07 am.jpg
If you could find a way to fix a drill in position and cut a slot wide enough for the chisel you could pair these two up so's with the drill running you just slide the chisel in and out to generate the hollow

Bob I just thought I would post again by way of update - yes, flap wheels are the go. The diamond cutting wheels create too thin an area. The flap wheel lets you get a decent surface area so you're not standing there for 5 minutes.

The flap wheels in the dremel are good at coverage, but don't really gouge out enough. When you've got a chisel with a considerable convexity (what has got me on this path is the pain of fixing up old chisels and finding out every damn one of them is badly convexed) you really need to honk off material. When I was giving the chisel a bit of a blast with the Dremel flap wheel, I went back to the stones and after about 20 laps, I had lapped out the hollow I made.

This would be an efficient way of sneaking up on a perfectly flat and polished back if you did not want a hollow left over mind you - but you're going back and forth from your Dremel and stones often.

I have picked up a 40 grit flap wheel for my die grinder that I think will be more effective for blasting off an area and will give it a go tonight.

Originally Posted by BobL

I agree about the ALOX wheel - if you have spares go for it.

Just after I posted yesterday I also thought of a dremel

As for quickly creating a hollow, a round flap wheel in a drill night work.
They come in different sizes and grits.
Screen Shot 2022-01-13 at 6.04.07 am.jpg
If you could find a way to fix a drill in position and cut a slot wide enough for the chisel you could pair these two up so's with the drill running you just slide the chisel in and out to generate the hollow