Lapping chisel and plane blade backs - a few tips

[rsser]

I remember now Ern,
"Lapping chisel and plane blade backs... a few tips"

I remember going to a Toowoomba Forum meet and greet, and MatthewA (Toolin Around) ?? showed how he polishes the back of chisels with the side of a solid timber wheel and polishing compound on a variable speed wheel. Good for any tool that you don't need a dead flat back on.... fast fast fast.

Yes, power honing/polishing is another project but for turning tools.


I guess our problem is that we (unrealistically?) put expectations onto flatness rates that should really be in the realm of machines.

Chisels only need to be realitively flat on the back... a small strip of flatness to meet with the bevel to give a nice sharp edge. The rest of the back should be 'near enough'... then you bang it into the mortice with a ball pein hammer.
I can't see the point to 'extreme accurate' flatness over the entire back... not from a working in wood useability or 'time benefit' vs 'results' perspective.
Agreed. Most of the tool tuning I've done exceeds my current capacity to control them; it's just something obsessive and distracting and beats the sterile exercises I have to do to rehab the broken wrist.


Same for plane blades - 'near enough on the back', polished on the back near the edge', then the bevel polished.

But thats not what you are doing are you?

No. I flatten maybe 25mm up the back and then polish as little of that as is consistent with not rocking the tool


You have entered 'shed time', and will only come out when you have reached mythical standards of perfection in relation to polished and flat 'backs'.
And along the way you'll work it out, find the best way to do it... and I'll steal that result and use it for my own dodgy ends.
LOL. Nothing special in what I'm doing; all the ideas come from someone/somewhere else. 'Shed time' - nice idea. It circles back on itself.


The comment about 'flat at this grade is not flat at that grade'... are you going beyond the flatness of the stones? e.g. are you looking for results greater than the materials you are using allow?

Yes and no. To be really anal I'd flatten the fine stones before each new blade back is brought to them. What I'm shooting for here is a 'good enough' result that sometimes involves a bit of fudging, ie. polish is achieved at the expense of some of the flatness that was achieved. Eg. the stone is slightly high down the centre from end to end, so I polish that tip rising against that at 4000 and 8000.

I think of diamond stones as the way to remove manufacturing marks or damage.... then uning them to lay the foundation for a quick polish through a few finer grades.
Yes, that's pretty much the procedure I've settled on. For now.

I dunno. An experienced woody might look at what I've done and say it's a load of rubbish, or it's way over the top. For me at the moment it's an interesting diversion and a great source of learning. I'm doing more and more comparative testing of diff chisels or planes applied to the same task to move beyond 'hearsay' and rule of thumb. Eg. can a fettled Stanley 6 with a Hock blade do as good a job jointing pine with some reversing grain as a V. BU jointer? Not a fair test unless the blades are similarly tuned.

Another tip however I would pass on: if chisel wood needs replacing do this before tuning the blade!

[Clinton1]

For me at the moment it's an interesting diversion and a great source of learning.

Thats a good part of 'shed time'.

I'm about to join you. Was just scraping the 3rd last of a pile of long boards, before moving onto the short boards... and hit a buried bit of schrapnel with the HSS blade in the scraper plane.

One of the downsides to buying timber from an area that was bombed.
Knocked a @3mm long chip out of the blade, almost as wide.
A tool steel, highly hardened and brittle bomb or artillery shell casing I guess. Timber had grown over and around it... what looked to be a knot was on the other side.


Up side, is that I got through 15 Teak boards (2200mm x a range of 230mm to 180mm wide)... so I only have to freak out about buried metal in the last 3 boards.

The O1 blades in the jointer and smoother needed 3 sharpenings during the task... where as the Academy Saws HSS blade in the scraper got all the way through just fine, untill it met its match with the buried metal. Guess it needed sharpening anyway.

[rsser]

Ouch!

Teak, nice. No need to wax the sole. Bombed teak?

Did you bring this back from Timor Leste?

(As a turner 'finds' are a regular source of timber but after trashing two bandy blades a metal detector has been a good investment).

Well, a c. 3x3mm chipout is going to provide you with a deal of meditation time.

Or will you take it out on a bench grinder?

[Clinton1]

No bench grinder in my back rumpus room Ern... but there is a 300 stone... stroke, stroke, stroke, x hundreds.
Yes, brought it back from Timor Leste... off a mate's family land in the eastern part of the island.
He'll be annoyed about it as he has a very bloody minded plan for all the trees that got hit, which don't include me getting any.

Here's a pic of a straight grain and boring board, scraped and wiped with metho... I picked the wildest grain I could get, and even some spalted sapwood and heart combination boards. Oily stuff, wipe meths on it and the rag turns brown from the oil coming off... and this was dried properly.

[rsser]

Fabulous. Worth the bugger*zing around.

If you're not in a rush I'd be happy to regrind your Williams bevel. As a turner, HSS grinding is something we do in our sleep ;-}

Should you need grounds to trust me, this is how I'd do it:

1. Joint the edge on a 60g alox pink wheel.
2. Slowly reshape the bevel to your choice of angle on the same wheel, leaving a smidgen at the tip unground
3. Finish the bevel on the Tormek at c. 220g.

Easy peasy. Turn-around time 1 day.

[Clinton1]

Thanks very much Ern... and I'm sure you could do it in your sleep.
But just finished on the 300. Veritas MkII is a wonderful thing.

One day I'll get a proper grinding/polishing/buffing set up. One day I'll do a lot of things.

[rsser]

No worries.

Yes, the V. Mk II jig is a wonderful piece of kit.

But I have to confess to a leaning now to a hollow ground bevel and then refining the edge by hand on some stones. At least that's with chisels. Quick and easy.

EDIT: as for lapping HSS blades, in my book this is an order of magnitude beyond all the practice wisdom out there. Caveat emptor!! I managed to do 3 Muji's quickly on the side of a Tormek wheel, which now needs cleaning and that's not a trivial task. For someone committed to this kind of work or a lot of HCS, yes, look at a machine. The Worksharp 3000 looks good to me.

I've just spent too much time flattening a tear-drop turning scraper. Not much bigger than the magnet in the pic above. One side I stopped after 500 strokes on coarse diamond before flipping it and getting a result on the other.

[Clinton1]

I did count.
V MkII and 600 strokes (up and back = 1) on 300 grit to remove the chip, then 10 or so wipes to take off the wire edge.
Then about 50 on the 6000 grit to polish the secondary bevel, again with the wire edge, a dozen or so strokes on the bevel again - these by hand.

300 to 6000 is a big jump, I know, but it works for me.

Tough material.... should be good for a long while, or 1/10 of a second with an encounter with another bit of metal.

[rsser]

Good result

[Clinton1]

Back into it... one board 'off the saw' (the colour is from time and the sun), the other jointed, smoothed, then scraped cause its nasty, nasty grain.

Guess this is why we put the time into blades.

Jointed with a 22" plane, smoothed with a LV BU Jack, heaps of tearout due to the wild direction changes and quilting and whatnot... scraped with the scraping plane.

Smooth and silky... pics don't do it justice, it will come up good with finish and the right light, but would never come up good with tearout all over it.

[rsser]

Hard work; brilliant result.

[Fuzzie]

I'd never accuse anybody of being anal about sharpening but there's a lot of enthusiasm showing up in this thread

I couldn't pass up this in the Aldi sale basket today. Originally $49.99, today $29.99.

Inspecting one of my own blades, here's a picture of the back of a Record #4 blade, sharpened on old oil stones, @ 60x and 200x. Now I'll be able to really tell if I ever get my lapping mirror smooth

[Fuzzie]

... and the hand sharpened bevel at 10x.

Ummh, now remind me, how many bevels should a plane blade have?

[rsser]

Well done Fuzzie.

I use a USB scope with turning tools and v. revealing it is.

But I'd say 'anal' is where you polish to 20,000 so you can see your own reflection (actually depending on the stone you can admire yourself with a mere 8000!)

Edit: we were posting at the same time.

Have as many bevels as you like! Only one counts in use.

[Horaldic]

I had a go at lapping the back of an older #7 today. Boy was it hard! I went through a Grieg piano concerto, a Prokofiev suite and a Schostakovich symphony and the course DMT stone still hadn't polished out to the corners of the blade at the tips. Must have been a good day at the works when the made that blade.

It was a new DMT too and I managed to rub a divot out of one finger. I'm thinking that perhaps an extra extra course stone might be the business to get the first stage of flattening done.

Up until today I was using oil stones of approx 240 and 600 grit (old Nortons) before cleaning the blade and moving to waterstones. It was a fiddle and I needed wider stones so I got hold of a course and fine diamond stone, I think 330 and 600 grit respectively.

They do polish the blade up very well with a much more even grit than I have previously experienced. The extra course is 240 grit which, in my book, isn't enough of a jump to 330. So, I'm thinking the extra extra course at 120 might be worth a try.

My only concern with this is that it might be over the top?