Tool Grinding Methods/Techniques

[Jelly]

As I posted a while ago, my tools suffered some severe exposure to the elements due to shed failure... Largely, wire wool, elbow grease and a quick sharpen were sufficient to sort them out, however one or two ended up badly pitted behind the cutting edge necessitating rather more material removal.

I ground two of them today, starting with a belt linisher which didn't work nearly as well as I'd expected, and then with a more conventional pedestal grinder, I achieved decent results in the end but can't escape feeling that I was missing something... The finishing machine had no work-rest which was unhelpful, but the multiple rounded facets it generated could only be down to an inappropriate machine, or poor technique.

The grinder was rather slower, due to more rapid workpiece heating (conveniently, it has a small tub for coolant which fits into the pedestal), but generated a single 20° bevel* quite easily, with a minor touch-up on the edge of the wheel taking any hollow out.

How would I be best approaching Grinding tools, other than slowly, with frequent cooling? My approach so far has been to set the workrest to 90°, square the edge up, and take it back past the worst of the pitting, (2-3mm), then turn off, set the work-rest to the desired angle and slowly work back towards that edge until I can't see any light reflected off it, then lightly dress against the side of the wheel, and sharpen on a stone as normal.

* I know that 25° & 30° are "normal" but for working with softwood, especially whitewood I favour a more acute angle, even if the edge is more fragile.

 

[AJB Temple]

I use Tormek T7 which runs slowly in a water bath and has jigs to hold the tool. Overheating is the edge is less of a risk this way. It's a bit laborious compared say with a knife makers set up with large capacity ceramic grinding belts.

 

[xy mosian]

I have found that a quick cooling dip doesn't work. My own technique is to grind two pieces alternately. Grind one, put in water to cool, grind the other, etc..
As for angle on a pedestal grinder I set the edge distance with a finger and rest that against the nearest edge of the tool rest, my rest won't adjust for angles. I don't really care what the angle is, as long as it is less than about 30 degrees.
xy

 

[Random Orbital Bob]

I have a pro edge (linisher), Tormek and a grinder and I ALWAYS use the linisher for fast steel removal as its the fastest and coolest (at speed). The secret is low grit belts (60g ceramic) which are new for the job.

 

[blackrodd]

I was taught cutter making hand held, making spindle moulder cutters for the Whitehill blocks and sharpening, and also
moulding cutters for the five and six cutting machines, this was for making different sized quadrant in pairs, all the usual
skirtings, torus, ogee, etc, splayed and rounded, top and side handrails etc, etc.
Straight cutters Longer than 3" wide were set up in the grinders for that job, up to 30" long planer irons were possible
A 60 grit wheel is best, 40 too course, and more than 60 will heat and burn the cutters too easily,
Then clean, straighten, or make any shaped grinding wheel necessary using one of these in the link below.
The diamond and stone "stick" don't actually clean very sucessfully and make a nasty dust too!
Any cutter shaping or straightening is carried out using the rest, for safety reasons, snatching, etc.
Then the bevel work is carried out free hand, and just before it's too hot to hold, use the water trough usually in the centre front of the grinder, to keep cool
Constant monitoring of the bevel consistency and angle are crucial for a neat, true and machine like finish, and not
burning the fingers at all!
All apprentice were taught this way and all 6 of us made cutters fairly regularly for the various machines.
WE don't worry about the "hollow ground edge" and never use the sides of the grinder wheel !
regards Rodders.
http://www.ebay.co.uk/itm/301569030653? ... EBIDX%3AIT

 

[Jacob]

Yep coarse grit for faster and cooler. Belt sander or linisher best to avoid hollow grinding.

I grind my own cutters too - matching pairs ideally, but they'd never cut together; one cuts, one is for balance. First the profile square on, then the bevel, then the clever bit - deepening all the hollows so the cutter will fit the profile when skewed at the cutting angle. Offering up to the sample at intervals. Actually more accurate than machine copying, surprisingly.

 

[Jelly]

Looks like I'll be wanting a coarser belt for the linisher then, and rigging up some sort of rest (I can't bring myself to use the guard as a rest for my hands to steady the tools).

I also managed to succesfully re-grind a v-tool which was chipped, though not without a few worrying moments and more material removal than I might have liked.

Rodd: Keeping fingers close to the edge and naturally feeling the heat is a good tip, my fingers will be unhappy long before the edge loses temper. As is keeping a coarse, slightly friable but we'll dressed wheel for these tasks.

Jacob:
Having first hand experience of the modern toolrom techniques I have trouble believing that hand Grinding is better than the current generation of in-block profile grinders and profiled in-machine joint stones. I don't however doubt that the hand Grinding method can match and in some situations better the older profile grinders which work from a template, or the pre-made clip-in tooling one orders in.

I've hand-ground 2 moulding plane cutters not so long ago based on a vague recollection of your advice on hand grinding profiles and it was surprisingly effective, and almost matched the sole straight off, the bevel ended up a bit messy though and took a fair bit of tidying up with slipstones to give a really good match and effective edge.

 

[blackrodd]

A linisher sounds like a good idea for flat irons or cutters, but do be careful not using side ways on, as the heat will
tend to build up on the "tail end", and also remember the Linisher belt can get worn and blunt and easily overheat,
It is not rejuvinating like a grinding wheel, fairly constant in grit, but steadily smaller.
Jacob, I'm not so sure about the computer ground cutters versus man freehand, we were pretty good, in our day, but having seen some computer ground cutters recently, they're pretty damn good and consistant too!
Regards Rodders

 

[Jacob]

.....
Jacob:
Having first hand experience of the modern toolrom techniques I have trouble believing that hand Grinding is better than the current generation of in-block profile grinders and profiled in-machine joint stones. I don't however doubt that the hand Grinding method can match and in some situations better the older profile grinders which work from a template, or the pre-made clip-in tooling one orders in......

I've had machine copies which haven't been that good and have needed a final hand fettle. It's all down to the operative and the machine. No doubt there are better machines.
Most sample are less than perfect and need some interpretation - the hand process of a final offering-up and fettling is the way to do this if you want perfection.

 

[blackrodd]

Believe it or not, behind our 6 cutter, was a wall consisting of 12"x 12" pigeon holes, It was 20ft long and 6ft high.
In these pigeon holes were filled up with all the patterns of profiles we made stocked and sold.
Tied up with string, was any reverse moulded pressure "pads" needed and written in pencil and sometimes over written in biro, notes on relief cuts, slitting saws etc.
Our spindle cutters for the whitehill blocks, were kept in 2 drawers 24" wide and about 30" deep, lined with louvre like
strips for each pair of cutters, perfectly balanced, rows upon rows, And I had made quite a few of those at the end!
I remember they were very heavy to lift out!
Regards Rodders

 

[Jacob]

Mine are in a biscuit tin.
A lot of them were one offs and often got modified for the next job - or another profile worked on one of the other edges. Basically look a mess, no serried ranks, more like shrapnel!

 

[Jelly]

Believe it or not, behind our 6 cutter, was a wall consisting of 12"x 12" pigeon holes, It was 20ft long and 6ft high.
In these pigeon holes were filled up with all the patterns of profiles we made stocked and sold.
Tied up with string, was any reverse moulded pressure "pads" needed and written in pencil and sometimes over written in biro, notes on relief cuts, slitting saws etc.
Our spindle cutters for the whitehill blocks, were kept in 2 drawers 24" wide and about 30" deep, lined with louvre like
strips for each pair of cutters, perfectly balanced, rows upon rows, And I had made quite a few of those at the end!
I remember they were very heavy to lift out!
Regards Rodders

That sounds extremely familiar to me!

The mill I worked in had just such a wall of racking, with profiles, reverse profiled jointstones, any knives already ground and a wallet with full diagrams, customer tolerances and helpful handwritten setup notes all carefully taped up into little packs and numbered, the opposite wall was the same, but with blocks, gang-saw spindles, saw plates and spares for the blocks all lettered.

I miss the timber industry, though perhaps I've donned my rose tinted glasses and am forgetting the reality of spending upward of eight hours a day in a dusty, noisy environment, with wildly varying working temperatures and backbreaking manual labour...