Grinding blades with power tools/sanders discussion

[Dissolve]

Hello all,

I am having a tough time re-establishing my primary bevels using a honing guide on my scary sharp set up, even with the coarsest of wet/dry and 3M films, so I'm looking into some form of power tool grinding set up.

I have a small home workshop, so space is a big factor which leads me to discuss and hopefully get some opinions on the following options;

1. Buy a bench grinder, make a jig to hold chisels and plane irons square.
2. Adapt my small belt sander much like Derek Cohen's jig/modification.
3. Buy a whetstone grinder
4. Use something else (which I'll discuss later)

I like whetstone grinders, but price is another factor, it seems to get a decent tormek(ish) set up you're looking at over £200, which at the moment is not possible so that's a "maybe one day" kind of thought.

Next up, the bench grinder. Cheap, seems you can get a 6" grinder for £30-£50 and making a jig would be relatively easy, but I have no other use for a bench grinder so the space would be my only real negative at his stage. I also like the hollow grind, my only concern would be that 6" might be too small a radius?

The belt sander, I have an Axminster belt sander which I don't use all that much, but I like the idea of adapting it into a a blade grinder, using an adjustable bar like Derek Cohen's design. Obviously I would lose the hollow grind with this, but it's a cheap option at the moment, and it's probably about the same size as a bench grinder to leave set up at all times.

Lastly, I had a strange idea to use my bobbin sander! I tried this out on an old unused chisel and was quite surprised, I squared up a block of timber, made the edges parallel, then clamped the chisel to the top edge of the block and used a 220grit sanding sleeve to slowly run the existing bevel across it.

I used the largest bobbin (around 3-4inches in diameter) and rather than pressing it straight against the bobbin I used a sweeping motion which made the hollow grind much less pronounced than a 4inch bobbin would create if I directly pressed the steel into the sander..

The results were actually quite good, but would need some fettling. The bevel ended up a slight hollow which was great but despite clamping the chisel totally square to the block, the edge ended up slightly off and slightly cambered. I checked the spindle of the sander and that was square with the table, so I guess the inconsistencies come from either the rubber bobbins being squashed by the washers load when installing, or perhaps the sandpaper sleeves are not uniform enough where the joins are?

I haven't read anything about using a bobbin sander for hollow ground bevels (probably because it's a bad idea) haha :lol: but it's something I already have and use in my workshop quite a lot, so if I could get the edges square and true I'd be happy to save the expense/space of buying a new machine.

What do you guys think? Any suggestions/advice on a cheap bench grinder set up or adapting sanders for grinding blades?

 

[wizard]

drop this over belt sander simples

 

[Dissolve]

drop this over belt sander simples

I do feel it's time to put my belt sander to some good use! haha

... or be sold.

 

[Trafalgar]

You might find this helpful:

http://www.finewoodworking.com/item/114 ... sharpening

He appears to be using a very expensive, old, and fine, Baldor grinder. 6" grinders are available for much less money.

He's honing on the grinding bevel using the hollow grind as a jig for registration.

Here is Brian Boggs' website:

http://brianboggschairs.com/

 

[Corneel]

Another idea is the grinder without the jig to keep blades square. I never understood the utility of these jigs. Absolutely square is rarely needed anyway and grinding is a lot easier when you can move the blade freely up and down and left to right without hinderance from a jig. The toolrest is jig enough.

 

[Cheshirechappie]

If you're happy with the bobbin sander results, carry on with that.

There is absolutely nothing at all magical about power grinding. It's exactly the same process as your scary sharp, just a lot faster, that's all.

There is another option that may be worth mentioning. Have a rummage on Ebay or at a car-boot sale for a hand-cranked grinder. They work a lot faster than back-and-forth hand abrasion on stones or abrasive papers, they don't take up much space, and they don't cost a fortune, and they don't need an electrickery supply. If you can find one with a 6" wheel, so much the better; replacement wheels are much easier to find than the commoner 4" hand grinders if you need a replacement. You can even lash up a wooden toolrest if you like, though I use mine virtually freehand, just rest on the bent metal 'toolrest' provided, and check the bevel angle with a little gauge, adjusting the grind until it's to your satisfaction. Grinding cambered bevels this way is a doddle. Another plus is that you can keep a couple of spare wheels with different crown radii dressed on the edge to regrind incannel gouges and hollow plane-irons should you ever need to. Very handy piece of kit.

 

[jimi43]

As previously stated on another thread...I would never have believed it but this baby....

...when married with a jig (yes jig!)...does a superb job of primary grinding...viz....

Definitely my first choice from now on...and flat too! FYI...that's a 5 mm iron!

I do believe these come in under £100...unless you find one at a bootfair that is! :wink:

Jimi

 

[Mark A]

Hi Jimi,

Any chance of a picture of your jig setup?

Cheers,
Mark

 

[swb58]

Don't forget about Chesirechappie's reply. A hand crank may not seem much of a step forward when compared to other types of 'power' grinders but I can assure you it is. It's simplicity may seem ridiculous but it works a treat, puts an even bevel on a 2" plane iron. That's good enough for me.

 

[jimi43]

Hi Mark

Certainly can show you my jig setup...

First I took of the stupid planer blade attachment and all that gubbins and just left the metal support.

This has to be level relative to the stone....

I've removed the infeed tank as it was getting in the way of showing you the jig...

The iron looks a bit wonky here but I can assure you it isn't...it's just not being held firmly against the rest.

You can see that by clamping the iron into the Veritas jig clamp...it can be made to slide back and forth across the grinder jig support rail...and thus back and forth across the stone as it rotates.

Water is fed onto the stone at all times and it doesn't really move fast anyway but this keeps the iron super cool!

And that's it.

I don't advocate this method over hand grinding with an old machine. You asked for a power solution and so that's what you got.

I don't use a hand machine simply because I want a perfect looking bevel..I'm sure a hand cranked stone would do an admirable job.

And if you really were to want a super quiet...quick method of flattening a face and restoring a bevel then I would suggest you try the EXTRA EXTRA coarse DMT diamond plate which I just reviewed HERE

For me...I'll do the flattening on that and bevel creation and repair on this machine. That would be my setup.

Hope this helps choose.

Jimi

 

[Mark A]

Hi Jimi,

Many thanks for the pictures of your setup, it's much appreciated. I'll check out the Veritas jig now.

Cheers,
Mark

 

[jimi43]

Hi Jimi,

Many thanks for the pictures of your setup, it's much appreciated. I'll check out the Veritas jig now.

Cheers,
Mark

You are most welcome and THIS IS THE JIG which is £25 which these days isn't too bad but I suppose you could make your own but really...is it worth it?

Cheers

Jim

 

[bridger]

Another idea is the grinder without the jig to keep blades square. I never understood the utility of these jigs. Absolutely square is rarely needed anyway and grinding is a lot easier when you can move the blade freely up and down and left to right without hinderance from a jig. The toolrest is jig enough.

this is mostly what I do. I keep a small engineer's square at hand and quench and check often.

 

[Dissolve]

Another idea is the grinder without the jig to keep blades square. I never understood the utility of these jigs. Absolutely square is rarely needed anyway and grinding is a lot easier when you can move the blade freely up and down and left to right without hinderance from a jig. The toolrest is jig enough.

this is mostly what I do. I keep a small engineer's square at hand and quench and check often.

I am actually leaning this way now.. a complete U-turn from my thoughts about a wet grinder/worksharp/sanding jig.

I've done a lot of reading and had some personal recommendations for dry grinding with a decent wheel, it seems that common sense goes a long way in regards to not drawing a temper. If I buy a cheap 6" grinder for £20-£30 and buy a white or pink wheel for it, I think it might be worth the learning curve just to practise on some old dud chisels before taking my plane irons/good chisels to it.

If I have trouble I'll re-think my opinion on a wet grinding system!

 

[Jacob]

I always grind with a belt sander. No jig necessary - it's dead easy freehand. Easy to camber too. Flat bevel or rounded bevel take your choice. No need to adapt or buy anything extra. You have to watch out for sparks though - they can set fire to dust, or melt plastic cases, if allowed to.
The Bosch type square box shape is good as it will sit on the bench top, upside down.
I've upgraded to a Sorby Proedge but it's only a small improvement on an ordinary belt sander - not least by being open with nowhere for sparks to impact..
6" grinder the worst option IMHO. You end up with a horribly hollowed out blade. If you try to keep it flat it ends up looking as though nibbled by rats.

 

[Dissolve]

I always grind with a belt sander. No jig necessary - it's dead easy freehand. Easy to camber too. Flat bevel or rounded bevel take your choice. No need to adapt or buy anything extra. You have to watch out for sparks though - they can set fire to dust, or melt plastic cases, if allowed to.
The Bosch type square box shape is good as it will sit on the bench top, upside down.
I've upgraded to a Sorby Proedge but it's only a small improvement on an ordinary belt sander - not least by being open with nowhere for sparks to impact..
6" grinder the worst option IMHO. You end up with a horribly hollowed out blade. If you try to keep it flat it ends up looking as though nibbled by rats.

I like the idea of a hollow grind to enable easier freehand honing, but I am interested to hear why a 6" hollow grind is horribly hollowed out? Have you run into problems using a hollow bevel?

I didn't have much luck free handing the bevel on a belt sander before but I might try again using a basic tool rest just to see what results I come up with! I have given up much hope using a bobbin sander because it leaves a "frayed" edge that isn't straight, even if I could make a jig to hold the blades square to it!

A lot of people seem to love/hate the 6" hollow and I'm interested to hear the negatives before I consider pulling the trigger on one!

 

[Cheshirechappie]

Using a 6" wheel to grind a bevel on a chisel or plane blade 3/16" thick (so a bevel 3/8" long, near enough) gives a hollow grind 0.008" (eight thousandths of an inch) deep - detectable, but not significant.

Nobody I know who grinds on a 6" wheel bothers at all about the depth of hollow grind - it's miniscule. There are some who hate the very idea of ANY hollow grind, and they're perfectly entitled to use their own methods, but to suggest that it'll horribly hollow out a bevel is overstating the case - it won't.

 

[Dissolve]

Using a 6" wheel to grind a bevel on a chisel or plane blade 3/16" thick (so a bevel 3/8" long, near enough) gives a hollow grind 0.008" (eight thousandths of an inch) deep - detectable, but not significant.

Nobody I know who grinds on a 6" wheel bothers at all about the depth of hollow grind - it's miniscule. There are some who hate the very idea of ANY hollow grind, and they're perfectly entitled to use their own methods, but to suggest that it'll horribly hollow out a bevel is overstating the case - it won't.

Fair enough! Each to their own I guess. I'll give the belt sander another whirl seeing as i have one to hand, but I've had plenty of recommendations for a 6" grinder so that will be my next stop as they can be had for under £50 with a wide white wheel.

Thanks for the suggestions, all useful!

 

[matthewwh]

I use 100 micron film with a guide for light maintainance grinding, reducing a secondary bevel for example takes about a minute if you keep them in check regularly.

For heavier work I now use a cheap bench linisher (poor mans pro-edge) with a 40 grit belt. It took a little while to get a feel for freehanding blades on it, hand grinding is a skilled craft in its own right so you can't expect to just sit down and be brilliant at it, but with practice you soon begin to make a decent fist of the jobs you do regularly. The linisher replaced a belt sander which also got the job done.

Very, very rarely will I resort to the 6" grinding wheel on the other end - way too fast and aggressive, in fact I'm thinking of replacing it with a polishing mop for honing carving tools.

A hand cranked grinder with a good quality wheel would be another sensible option, they go for very little money secondhand and are surprisingly effective.

 

[Dissolve]

I use 100 micron film with a guide for light maintenance grinding, reducing a secondary bevel for example takes about a minute if you keep them in check regularly.

For heavier work I now use a cheap bench linisher (poor mans pro-edge) with a 40 grit belt. It took a little while to get a feel for freehanding blades on it, hand grinding is a skilled craft in its own right so you can't expect to just sit down and be brilliant at it, but with practice you soon begin to make a decent fist of the jobs you do regularly. The linisher replaced a belt sander which also got the job done.

Very, very rarely will I resort to the 6" grinding wheel on the other end - way too fast and aggressive, in fact I'm thinking of replacing it with a polishing mop for honing carving tools.

A hand cranked grinder with a good quality wheel would be another sensible option, they go for very little money secondhand and are surprisingly effective.

The hand crank might be a good option for a few reasons come to think about it.

It's definitely one of the simpler options, although the way my bench is set out I would like to be able to move whatever I chose into the corner rather than overhanging the bench, but I'm sure I could get creative if i found it to be a permanent fixture in the workshop.

Now to scour ebay and see what I see!