flattening chisel backs with lapping film

[madge]

Hi all, I recently took a plunge down the slope and got a set of blue spruce paring chisels and today I got around to flattening the backs. After refreshing my memory with a couple of youtube videos from lie nielsen and rob cosman I set to work with lapping film on float glass but the results were much less than my expectations. Even on the coarsest grade of 40 microns I achieved patchy results with all but the smallest chisels showing a polish in the centre and a good couple of mms missed around the edges. Having achieved reasonable results on a set of ashley iles in the past I was surprised that the blue spruces didn't succumb in the same way. I'm pretty sure that the film is flat with no air bubbles and I tried to apply pressure evenly and not rock the chisel as I moved it. I spent close to an hour on the 1/2 inch size and didn't end up with an even polish. I'm thinking that 40 microns just isn't coarse enough but I've scoured the internet for a coarser grade and the next size seems to be 100 - is this too coarse? I have a diamond stone with a 1000 grit side too, would that be finer than 100 micron film and suitable for the first stage? Thanks in advance for any ideas.

 

[fluffflinger]

http://www.youtube.com/watch?v=CBZ8446KqkM

This should help. I've prepared several chisels and plane irons using the 100micron lapping film, very aggressive and makes quick work of the hardest steel.

Hope this helps.

 

[Jacob]

It takes about 10 seconds to get a new good quality chisel into use. You are seriously wasting your time!
Who made up these weird rituals and why do people go along with them?
Wake up!

Or to put it another way - if a chisel needs 'preparing' it isn't finished. Send it back to the maker and tell them to do it.

 

[Cheshirechappie]

It takes about 10 seconds to get a new good quality chisel into use. You are seriously wasting your time!
Who made up these weird rituals and why do people go along with them?
Wake up!

Or to put it another way - if a chisel needs 'preparing' it isn't finished. Send it back to the maker and tell them to do it.

OK, I'll bite. How do you get the manufacturer's grinding marks off the flat face of a new chisel in 10 seconds, Jacob - especially as you advocate reasonably priced new chisels, the sort that usually have grinding marks?

 

[Jacob]

It takes about 10 seconds to get a new good quality chisel into use. You are seriously wasting your time!
Who made up these weird rituals and why do people go along with them?
Wake up!

Or to put it another way - if a chisel needs 'preparing' it isn't finished. Send it back to the maker and tell them to do it.

OK, I'll bite. How do you get the manufacturer's grinding marks off the flat face of a new chisel in 10 seconds, Jacob - especially as you advocate reasonably priced new chisels, the sort that usually have grinding marks?

I don't. I hone the bevel until a wire edge comes up (across the whole width - very important) and then take it off with the chisel face flat on the stone. 10 secs plenty. If it's so bad you can't sharpen it in 10 secs it's cr*ap - send it back.
It's not a major feat of technology to produce a 10 seconds usable chisel - amongst the simplest tools you can buy. If no good get your money back, don't buzz about lapping and polishing.

 

[Cheshirechappie]

Thank you, Jacob. That explains a lot.

 

[Jacob]

The Axminster cheapies I bought were all usable in no time at all. I go on about them a lot not because I'm trying to promote them but they are the only set of chisels I've ever bought, as distinct from random selection of individual ones.

 

[Peter Sefton]

We do have 80 micron (180 grit) lapping films - 100 is pretty coarse for such high quality chisels, the finer the abrasive the flatter it will be and the more imperfections it will highlight on tools.

I have never lapped Blue Spruce but would be reluctant to do so on very coarse abrasives as I would hope the chisels are made to finer tolerances than that. Lapping on glass plate does show up all manufacturing imperfections which you may not show up with other sharpening mediums.

 

[marcros]

i have to admit that i have lusted after some blue spruce chisels since i first saw them online. I would be disappointed that they need so much flattening.

I see on their website that they have some supplier issues- might be worth an email to ask whether you may have a bad set?

 

[carlb40]

i have to admit that i have lusted after some blue spruce chisels since i first saw them online.

Yeah me too, i love the bench chisels with curly maple handles

 

[madge]

many thanks for the speedy and insightful replies. I will try the 100 micron film and the smooth side of the diamond stone on an old chisel and see what results I get. Is there a precise relationship between grit and microns?

marcros I think I have you to blame for the chisels, I remember you mentioning them a while back before I knew anything about them! I had a newsletter from classic handtools last week mentioning that they'd acquired some tools from a collector, including blue spruce chisels and I caved. So I'm not sure when they would have been made but I might drop blue spruce an email - though I have confidence that it's my technique or approach that's at fault!

 

[vally bar]

I've got to be honest I have just watched that video and never seen such a load of old cobblers like it, totally designed to sell tools that are unnecessary. If you treat your chisels like that whatever you do do not put them anywhere near hardwood as you will blunt them.

 

[bobbybirds]

I have a set of 9 bench chisels, set of 4 dovetail paring chisels, pair of skew chisels and a fishtail chisel, all from Blue Spruce, and every single one of them was dead flat out of the gate and only required a slightest bit of polishing on my 4000/8000 Norton waterstone. I know a few people who also have BS chisels with the same experience as me, as well as the multitude of people I have read about on the forums with the same experience as me, and I have never once heard an experience like yours.

Don't know quite what to say except that if it is a fault with the tool, Dave Jeske is an extremely decent fellow and would not leave you twisting in the wind, but I might try and see if there is something else that may be contributing to your issues. I have never used lapping film on glass so I can't really comment there...

 

[ColeyS1]

I've wasted hours of time in the past flattening backs of chisels/plane irons. My Ashley mk2 ones are slightly curved anyway so needed seconds to polish the back of the cutting edge. My marples site chisels get a much harder life. If its taking to long to polish the backs of them, I just use 'the ruler trick' which has saved hours of time.

 

[Jacob]

.....If its taking to long to polish the backs of them, I just use 'the ruler trick' which has saved hours of time.

:shock: Dear oh dear that's strictly against the rules! :lol:
I think this polishing myth has come about because any old chisel which has been well used, will over time acquire a flattish and polished back, with use and frequent sharpening. Somebody has extrapolated from this that that they should be polished and flattened from new.
There may be some chisel jobs which need this level of preparation but I guess they are very rare.
See what-is-the-last-useful-thing-you-did-with-a-chisel-t67886.html

My Ashley mk2 ones are slightly curved anyway so needed seconds to polish the back of the cutting edge

Ditto my axminster cheapos. Very slightly hollowed faces like the best Jap chisels, making sharpening easy and almost instantaneous. I've no idea how consistent their production is so I wouldn't take this as guaranteed! I've only had my hands on the one set.

 

[bugbear]

If the back of a chisel isn't flat enough, you get (on some scale) a serrated edge. It's the same principal as is used by toothing irons.

BugBear

 

[GazPal]

Chisel flats naturally become polished through the sharpening process over a period of time and generally don't need a lot of work unless seriously out of whack (Badly pitted) bent like a boomerang. Even if a blade is in poor condition the area in need of work is typically a small section directly adjacent to the cutting edge. The resulting polished area expands with repeated whetting and burr removal.

I'm not strictly an advocate of back bevels on chisels, but much depends on a tool's primary roll and back bevelling can prove a good rescue exercise when re-sharpening types such as roughing-out chisels.

In the case of paring chisels, we seldom use the full blade length when paring, but much depends on user preference and if the flat on a new blade is out of straight beyond a reasonable degree or below parr the simplest solution is to return it for replacement or refund. Much depends upon working tolerances and personal technique.

Grind marks should not be present on the more expensively branded chisels and ideally shouldn't be exist on any chisel flats. Sadly it's not an ideal world we live in and we sometimes find ourselves needing to put more work into tool prep than need be, but the work involved should be minimal.

 

[Jacob]

If the back of a chisel isn't flat enough, you get (on some scale) a serrated edge. It's the same principal as is used by toothing irons.

BugBear

If you can't sharpen a new one easily and instantly it is faulty and should be sent back.
It's like getting a saw - traditionally you are expected to sharpen them so that's OK, but you aren't expected to have to cut the teeth!

 

[Sheffield Tony]

I'm going to risk agreeing with Jacob. I bought a set of Crown mortice chisels, and found a small hairline crack in the blade of one, and another that was just a bit roughly finished. They were replaced quickly, without the slightest quibble. If it's not good enough, the manufacturer needs to know about it.

 

[Jacob]

I've looked at a few old well used and cared for chisels (from ebay etc) and the flat often isn't as flat as it looks. I think this is because when flattening the face there is a natural tendency to put more downwards force towards the edge, with your left hand fingers bearing on the last 2 inches. Over time this produces a very shallow bevel - more of a convex face, hardly noticeable. This doesn't affect usage in any way, in spite of the rituals and beliefs of the flatteners!