Sharpening LN Chisels

[SVB]

Folks,

The gradient of the slope is increasing!

I have been dropping the odd hint re getting a decent set of chisels for a while with SWMBO. Last night I went for it and suggested I get a set of LN's, expecting to have to scrape her off the ceiling and then compromise on a set of AIs / Victor's as I am a reasonable chap.

To my surprise, she said 'OK' and carried on reading.

So, off to APTC next week to buy them. BUT, ......

To this point I have been sharpening my Stanley Builder's specials on my Jet (Tormek clone) wet wheel which I mainly bought to slow the rate of dry wheel grinder erosion on my turning tools.

I expect this will have to stop as it will introduce a concave edge or would I still hone on the leather wheel?

What do the assembled masses suggest? I don't have 40 years of apprenticeship behind me so I expect some sort of guide will be useful also.

Many thanks in advance.

Simon

 

[woodbloke]

LN chisels use A2 steel which require a slightly higher honing angle than standard. I grind the primary bevel at 23deg on the Tormek and then hone a secondary bevel at 30deg using the green DMT extra fine diamond stone. A third micro-bevel (this is a tiny) is then produced at 32deg using the 10000g Spyderco ceramic stone. I use a modified Eclipse honing guide and a 'bench hook' arrangement to instantly set the correct projections for the different angles - Rob

 

[Woody Alan]

You'll find it'll be absolutely ages before you will want to go near a grinding wheel with those chisels. A touch up on a diamond stone to rehone the edge from time to time is all you'll need to do and polish the back. Grinding removes a fair bit of metal and at those prices you don't want to do it very often. Only grind the chisel when the secondary bevel gets to the stage that the chisel is difficult to sharpen. For the time taken to sharpen a chisel on a stone the Tormek is a lot of messing about. Do not even think about polishing or flattening the back of them on the side of the wheel.

Alan

 

[Mr Ed]

I would suggest honing by hand on your choice of stone. There is great debate about the various merits of water, oil or diamond stones which is a thread in itself. I use an eclipse honing guide on diamond stones and would recommend it as an easy way of working.

The Jet will still be useful for periodic regrinding of the blade and the fact that it introduces a slight hollow is a good thing. This means that when you hone this ground radius on a flat stone it only contacts at the ends of the bevel, meaning less metal to remove to hone the blade. Once your honings have increased the area of metal to be removed each time, you regrind to form the hollow again.

I would forget the leather honing wheel as its too easy to lose the nice sharp edge you have achieved and is also unecessary if you have honed on a 6000-8000 grit stone.

Cheers, Ed

 

[Derek Cohen (Perth Oz)]

Hi Simon

I have a slightly different approach to sharpening and chisel use to those who replied above. The way you sharpen can affect the way you will be able to use your chisels.

That you have a Jet wet grinder places you in the pound seat.

I would use this to create a hollow grind at 30 degrees, taking the hollow right to the edge of the bevel. No secondary bevel.

Once this is done, you only need a couple of swipes on a 1000/1200 waterstone (to straighten the edge), and finish on a 6000/8000 waterstone (or these equivalents). Balance the bevel on the hollow and you can do this freehand. You will create a fine microbevel, and you will be able to re-sharpen this many times before regrinding.

What is wonderful about the Jet/Tormek is that it keeps the heat down and you can grind to the very edge of the steel without fear of changing the temper.

The reason I recommend that you hold at the same angle that you grind is that this maintains a coplanar flat bevel, which you can use bevel down with registration across the bevel. You cannot do that if you introduce a secondary bevel.

My experience with A2 blades, mainly from LV, is that they need a regrind to get to the tough steel. I get better performance at 25 degrees than they are meant to get.

Regards from Perth

Derek

 

[Handworkfan]

I've had good results with LNs using a diamond stone for honing and a waterstone for the final polish. I only use the Tormek for grinding when the honing bevel has got too wide (after a very long time and lots of honings).
I can see Derek's point, although I've not tried his way. the one thing I would say, echoing at least one earlier poster, is for pete's sake don't try to flatten the back on the side of a Tormek wheel whatever the instructional DVD might say! (anyway, with LN chisels you don't need to flaten the back so much as polish it - again on a flat stone).
I'm coming to the conclusion that the law of diminishing returns applies to sharpening as to other things - there comes a point where the fuss we make produces smaller and smaller improvements. find a method that gets a good edge, learn to do it quickly and effectively, and stick with it. I've adapted David Charlesworth's approach (you might like to check out his DVD on chiseol preparation) to suit my own needs, and find it fine.

 

[woodbloke]

The bevel balancing trick I first saw in one of JK's books. He used a hand cranked grinder though (if memory serves) to produce a deeper concave bevel (smaller wheel) than you might expect on a Tormek - Rob

 

[SVB]

Many thanks to all who took the time to reply - the fact some of you are on the other side of the world never ceases to amaze me - thanks to all again.

I have gone down the route of a japanese 6000 grit stone from APTC for honing my new babies. This seemed to provide the best compromise between performance, durability and cost. I am a little nervous that the 1/8" chisel will groove the stone at the first time of asking but I am hoping a light touch will prevail!

According to the literatre, when re-graded the jet wheel is approx 1000 grit so I expect this will do the job when I have re-honded once too many times.

Regarding the backs, should I give them first go on the stone while it is 100% flat being new and get them out of the way or I have some 5 micron lapping film I could use that we use at work for fibre optic polishing or is this way OTT?

All the best and thanks once again for all the helpful comments and thoughts so far,

Simon.

 

[woodbloke]

.

I have gone down the route of a japanese 6000 grit stone from APTC for honing my new babies. This seemed to provide the best compromise between performance, durability and cost. I am a little nervous that the 1/8" chisel will groove the stone at the first time of asking but I am hoping a light touch will prevail!

According to the literatre, when re-graded the jet wheel is approx 1000 grit so I expect this will do the job when I have re-honded once too many times.

Regarding the backs, should I give them first go on the stone while it is 100% flat being new and get them out of the way or I have some 5 micron lapping film I could use that we use at work for fibre optic polishing or is this way OTT?


Simon.

A 6000g stone will be good for a final bevel, something coarser will initially be needed for back flattening, if needed on LN chisels (and they won't need much :wink: ) Be aware that the waterstone will start to go concave at the drop of a hat :evil: which will be very bad news if you do continuous back flattening.
If the Jet wheel is anything like the Tormek, the so called re-grading stone is pretty much useless, you're far better off truing the stone again with a diamond tool accessory to bring up a new grinding surface

 

[SVB]

Woodbloke,

I agree the re-grading stone will not true the surface of the stone, you rightly say the diamond tool is for that purpose - however, I did think use of the re-grading stone would result in effectively a finer stone for grinding. Have I got this wrong or are you comparing the effectiveness to a suite of individual waterstones?

BRgds
Simon.

 

[woodbloke]

Woodbloke,

I agree the re-grading stone will not true the surface of the stone, you rightly say the diamond tool is for that purpose - however, I did think use of the re-grading stone would result in effectively a finer stone for grinding. Have I got this wrong or are you comparing the effectiveness to a suite of individual waterstones?

BRgds
Simon.

Simon - you need a coarse finish on the Jet grindstone to remove metal for the initial primary grind (which will come a lot later on after quite a few honings of the secondary bevel(s)) You'll find that with use the surface on the Jet stone becomes less efficiant...not glazed, but it ceases to cut quickly and the grading stone has little or no effect. I don't use my grading stone at all and just use the diamond tool to resurface the Tormek stone.
I'm suggesting that the 6000g stone is good if you want to use waterstones. I (any many others hereabouts) have been down that path and have switched to diamond stones (DMT) Try the waterstone but be aware of the pitfalls as any mistakes you make will ultimately be expensive (if you're using them to sharpen LN chisels) and you're not familiar with just how fast they wear. The main problem is that when you flatten the backs after honing, if the stone is not dead flat but concave you'll wear away the corners of the chisel at an alarming rate, effectively rendering them useless unless you then regrind to return to a flat surface. I once ruined a complete set of expensive Jap chisels this way 'cos I did'nt realise in time - Rob

 

[dunbarhamlin]

Hi Simon
I'd second checking out the David Charlesworth chisel prep DVD.
Without any mentoring, it would be very easy to degrade the 'backs' of those nice new tools (Got the T-shirt? I must have worn out several before I mended my ways )
In particular, I'd avoid lapping with a side to side movement on the the 1/8" (and perhaps the 1/4") - very easy to roll such a narrow blade.
Cheers
Steve

 

[neilyweely]

The reason I recommend that you hold at the same angle that you grind is that this maintains a coplanar flat bevel, which you can use bevel down with registration across the bevel. You cannot do that if you introduce a secondary bevel.

You know what, I never really thought of that. Obvious really. Better go and sort my chisels out.

neil

 

[jonbikebod]

The reason I recommend that you hold at the same angle that you grind is that this maintains a coplanar flat bevel, which you can use bevel down with registration across the bevel. You cannot do that if you introduce a secondary bevel.

You know what, I never really thought of that. Obvious really. Better go and sort my chisels out.

neil

I am with Derek on this. Because I used to carve, it always seemed to me cabinet makers were missing a trick not having a single (initially concave) bevel. I am in the middle of hanging 5 doors and not being able to use a chisel bevel down for all those shallow rebates would for me be exceedingly frustrating.
I just hollow grind the original L-N bevel which is usually between 25º and 30º. I find that edge to be very tough and so it seems does Rob Cosman. At Westonburt last summer he was grinding his L-N’s at a very low angle (can’t remember what, maybe 17º?). I haven’t tried this as too acute/weak a grinding angle would loose a lot of expensive steel but sub 30º honing seems to work well in the normal range of woods.
For the final hand balanced hone I use 2500 grit scary sharp but any modern aggressive polishing grade of ceramic, water stone etc works depending on preference.
Jon.

 

[Handworkfan]

Regarding the backs, should I give them first go on the stone while it is 100% flat being new

Don't bank on it! The fact that the stone's new doesn't guarantee the flatness you want for a fine chisel back.. I'd check it first - pencil-hatch the surface adn rub it on wet-and-dry supported on float glass. I wouldn't be surprised if you find that not all the hatchings disappear at the same time.
As a matter of principle I never rely on the accuracy of any new piece of kit until i've checked it out.

 

[SVB]

Good point Handworkfan - will do!

I am guessing something like 240 or 320 grit is best to flatten the stone or is this a little subtle?

Thanks all so far - this site should really apply for academy status, the amount I have learnt with a couple of basic questions ......... :shock:

Simon.