# floatglass as a surface plate thickness?



## ali27 (1 Dec 2010)

I see most guys are using about 10mm thick
floatglass as a surface plate.

I see the granite surface plates are usually 7-10
times as thick. Even if one supports the 10 mm
glass I am guessing it wil bend when one puts
lots of pressure on it(flattening planes).

So I asked about 19mm and 25mm float glass
and these are way more expensive than 10 mm
floatglass. 

Could I not just buy a few 10 mm thick plates 
and put them on top of each other? Is significantly
cheaper than 25mm floatglass.

I was thinking of putting 3-4 10mm thick floatglass
plates on top of each other with some newspaper in
between them. Don´t know if the newspaper would
make any difference, but I thought maybe it would
support the floatglass(it is not superflat).

What do you guys think?

(I have a feeling BugBear will respond to this topic,lol)

Ali


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## hanser (1 Dec 2010)

Just take the 10mm slip and pop it on a piece of MDF to provide a bit more support and something to hold/clamp. Use a thin bed of silicone sealant to bed the glass.


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## MickCheese (1 Dec 2010)

How flat is flat and how flat does it need to be?

I am guessing 10mm float glass is sufficiently flat enough to be fine for most woodworking application and sharpening most woodworking tools.

Is this not bordering on OCD?  

Mick


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## George_N (1 Dec 2010)

You'd be using a relatively short piece of glass and, yes it will bend but by so little that it won't have a detrimental effect on your sharpening/lapping.
In my early working life I was a histology technician and part of the job was to sharpen microtome knives (used for cutting 3 to 5 micron sections of tissue...everything from brain to bone...for microscope slide preparation). All our knives were sharpened on a machine that had a 10 mm thick glass lapping plate. The knife was held still and the plate moved under it with an action like a random orbit sander Hope this ramble helps.


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## ali27 (2 Dec 2010)

MickCheese":34pmmbb8 said:


> How flat is flat and how flat does it need to be?
> 
> I am guessing 10mm float glass is sufficiently flat enough to be fine for most woodworking application and sharpening most woodworking tools.
> 
> ...



No, because you have not understood what I am trying to
do. 

I think floatglass flatness is fine, but it bends when trying to 
flatten bigger planes on it.

George_N, lapping small planes are ok I think on floatglass,
but bigger, heavier planes will definitely make the floatglass
bend(which you don´t dispute), but by too much to my taste.

Ali


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## Mooeee (2 Dec 2010)

I can't see why you are saying that float glass bends and 10mm is not good enough for bigger planes, are you only supporting the glass at the ends???

If you are support all of the surface area under the glass then there should be no bending to worry about.


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## ali27 (2 Dec 2010)

Mooeee":1psx6vud said:


> I can't see why you are saying that float glass bends and 10mm is not good enough for bigger planes, are you only supporting the glass at the ends???
> 
> If you are support all of the surface area under the glass then there should be no bending to worry about.



Mooeee, the question is whether the total stiffness, of the 10 mm
glass plate and that what is supporting it, is enough to not bend
under the tension which is created by the weight of the plane and
the forces one applies whilst trying to flatten.

Granite surface plates are 3-4 inches thick. That is 7-10 thicker
than the 10mm floatglass some(me included) are using to flatten
planes.

Ali


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## warrenr (3 Dec 2010)

My 10mm float glass is 1m long and 125mm wide. It sits on a 25mm thick piece of MDF 300mm by 1000mm as suggested on a separate link on this site for making a frame for the glass and to hold the abrasive paper. The whole sits on my work bench which has been flattened. This seems to me good enough for my use.

Whatever you do you will always have some flexing both of the lapping base and the plane body itself depending hwo it is held and the planing effort. At some point you have decide what is fit for purpose. The only way to judge this for yourself is through use and whether you obtain the result and finish you need.

Early wood craftsmen produced finely constructed, beautiful and durable pieces that I could not hope to emulate with my far more sophisticated and accurate tools. 

Richard


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## studders (3 Dec 2010)

Not only do I think that any Metal Plane is going to distort, to some degree, in use with varying pressure, I also think that the Plane will 'move', to some degree, in varying temperatures. So I think worrying about very minor movement of 10mm float glass supported on MDF is pointless.


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## Harbo (4 Dec 2010)

We are talking about woodworking here not extremely high tolerance machining?

My granite surface place is only 50mm thick so should I discard it - I do not think so?

I use 10mm float glass with my 50mm thick Beech Bench top as support - I cannot think that will deflect enough to make any noticeable difference?


Rod


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## Jeff Gorman (4 Dec 2010)

I fear that whatever precautions we take, the perfectionist will want to finish the 'ground' surface by scraping.

Scraping details at http://tinyurl.com/2w2n4jw
General stuff at http://tinyurl.com/yby9sne

Jeff Gorman, being dogmatic
http://www.amgron.clara.net


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## Jacob (4 Dec 2010)

ali27":auxqz5d1 said:


> I see most guys are using about 10mm thick
> floatglass as a surface plate.......


Most (woodworking) guys don't "surface" at all, in my experience. It's a tooly thing!
Personally I use a sheet of wet n dry on my planer bed. Held in place by wetting with white spirit.
Or wet n dry, dry on a thick piece of mdf is good enough for most woodworking tools IMHO.


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## GazPal (5 Dec 2010)

Jacob":13s0grz7 said:


> ali27":13s0grz7 said:
> 
> 
> > I see most guys are using about 10mm thick
> ...



Most lads don't bother getting into unnecessary flattening and the present fashion toward the topic seems to be borne of internet based information and not so much from more commonly long held workshop practices which tend to take the form of a far simpler approach. As Jacob rightly suggests, a few simple swipes across some 200 grit wet & dry bedded on a jointer bed or pre-fabbed board is generally more than enough when checking for and flattening problem surfaces. :ho2 

An often overlooked tool for checking surfaces for flat is the simple spirit level. :wink: Good ones are typically accurate to within 0.5mm per linear metre, which is more than enough accuracy for most craftsmen's basic needs.

Unless a tool is seriously out of whack (Heaven forbid :shock: ) , there's no real need to become over zealous (hammer) regarding tolerances. For 99.9% of the time, a new professional quality tool's performance can easily be improved via a very basic set-up, routine maintenance and correct blade sharpening practices. These three activities are very often more than capable of producing results that elevate tool performance to a point where it can compete with the more expensive examples out there. Apart from saw blades, surfaces don't really need to be mirror polished, or refined to within a micron of absolute perfection. The acts of working timber and proper tool maintenance will tend to keep contact surfaces clean, but little harm comes from cleaning user tools with a little white spirit and wire wool (Before re-oiling) if you want to keep grime build-up at bay and pieces picture perfect.


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## studders (5 Dec 2010)

Having first stated that I agree with Jacob and GP.... I would add that there is nothing wrong with polishing your tool to within an inch of its life, if that's what floats yer Boat. 
Sometimes I do, sometimes I don't, just depends what mood I'm in as I find it quite therapeutic. 
I can understand those who 'just want to get on with it (wood mangling)' and those, seemingly mainly hobby, who like shiney shiney.
What does get on my mammaries is those 'experts' on t'net who say tools have to be polished to infinity (and beyond) to work properly. Tosh.


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## Alf (6 Dec 2010)

GazPal":psg8mtpa said:


> Most lads don't bother getting into unnecessary flattening and the present fashion toward the topic seems to be borne of internet based information and not so much from more commonly long held workshop practices which tend to take the form of a far simpler approach.


I think the internet-based stuff is as a result of reaction to magazine articles, books and DVDs, rather than the internet being the progenitor. The internet merely gives things the clout that's an inevitable result of many people apparently advocating the same thing.


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## bugbear (6 Dec 2010)

Any fool can see that a plane with a badly warped sole won't work, and that it either needs fixing or replacing.

After that it's all just a question of degree.

BugBear


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## Jacob (6 Dec 2010)

bugbear":fnf4fqcp said:


> Any fool can see that a plane with a badly warped sole won't work, and that it either needs fixing or replacing.
> 
> After that it's all just a question of degree.
> 
> BugBear


Well yes but these are fairly unusual. 
A lot of beginners could easily get the impression that every tool which comes their way is in dire need of a total makeover, or that if they can't plane easily it's the plane's fault and not their own lack of practice.
Nothing wrong with tool polishing of course, but it can get in the way of woodwork!


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## bugbear (6 Dec 2010)

Jacob":1yolxc6v said:


> bugbear":1yolxc6v said:
> 
> 
> > Any fool can see that a plane with a badly warped sole won't work, and that it either needs fixing or replacing.
> ...



There are definitely some cast iron bananas(*) out there! IIRC you owned one of them for a while.

But sole flattening should certainly not be part of "stage 1" cleanup and restoration of a s/h tool. 

To me it comes under "advanced tuning and fettling".

BugBear

(*) David Savage IIRC


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## ali27 (7 Dec 2010)

bugbear":v1nnqtdl said:


> Jacob":v1nnqtdl said:
> 
> 
> > bugbear":v1nnqtdl said:
> ...



Bugbear,

What do you think about my idea of using several(3-5) plates of floatglass on top
of each other to provide the necessary rigidity?

Ali27


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## bugbear (7 Dec 2010)

ali27":55m4p2it said:


> What do you think about my idea of using several(3-5) plates of floatglass on top
> of each other to provide the necessary rigidity?
> 
> Ali27



I think that would be going to a lot of complication and effort to avoid buying a cheap granite surface plate of certified accuracy.

How much does your glass cost?

How big a plane to you hope to flatten?

Do you have other uses for a reference flat?

However, as Jacob sort of pointed out, if you already have something you trust be flat and rigid enough, just use it.

Personally I don't have a large cast iron power too (no room), and my surface plate cost 14 US dollars.

BugBear


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## ali27 (7 Dec 2010)

bugbear":1j814686 said:


> ali27":1j814686 said:
> 
> 
> > What do you think about my idea of using several(3-5) plates of floatglass on top
> ...



Bugbear,

5 pieces of 60cm by 10cm by 1 cm cost 35 euro. I think weighs about 10kg
not sure. If I want a surface plate with that length(not counting diagonal)I would be paying about 100 euros or so at least and weight 50 kg or so(24´ by 18´ 4´).

Check this list:
http://www.mw-import.de/shop/pruefplatt ... atten.html

My biggest plane now is a no6, but I will buy no7 in the near future.

I don´t have any other uses for now, but will I think in some time.

Ali


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## bugbear (8 Dec 2010)

ali27":1qepskuv said:


> Bugbear,
> 
> 5 pieces of 60cm by 10cm by 1 cm cost 35 euro. I think weighs about 10kg
> not sure. If I want a surface plate with that length(not counting diagonal)I would be paying about 100 euros or so at least and weight 50 kg or so(24´ by 18´ 4´).
> ...



The plate you show is far too small for lapping, and much bigger than you need for "reference flattening". To flatten any plane up to 22" (a #7) using the process I recommend, you only need a 12"x18" reference. 

Indeed, if you use the method I recommend, the loading forces on the reference and dramatically lower than lapping, and the requirements for rigidity lower, so you could probably simply use your 10mm glass, taking the recommended precautions.

I used my surface plate to make the rule in my s/h Moore & Wright combination square straight and parallel (*). It was severely saddle-backed from a lifetime of use.

It's nice to have something you absolutely_ *know* _to be accurate within fine tolerances.

BugBear

(*) actually, I used the surface plate to make one side straight, and then used a micrometer to bring the other side parallel.


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## ali27 (8 Dec 2010)

bugbear":3on3t1i8 said:


> ali27":3on3t1i8 said:
> 
> 
> > Bugbear,
> ...



Bugbear, the floatglass plate I wrote about is actually smaller than the granite plate you suggest. If you mean longer ok, but a 12´´ by 18´´ granite plate is bigger than a 60cm by 10cm wide float glass plate.

Also couldn´t I use three float glass plates to create 3 flats? I have never done 
this technique, but once understood it should be quite straightforward, no?

One could always correct the flattness of those float glass plates my the 3 surface
technique, but with a granite plate you wont know after a while.

Also 5 pieces of 60cm by 10cm by 10mm thick pieces of float glass weighs only
about 10kg or so I think. A granite plate with a diagonal of 60 cm would be much
heavier. I have a small room.

Nice job on the combination square!

I will be doing scraping once I have a surface plate. I have not yet decided whether
or not to buy a granite plate or float glass.

Where did you get your scraper? Is it HSS or carbide?

Ali


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## bugbear (8 Dec 2010)

ali27":2cwabxfs said:


> bugbear":2cwabxfs said:
> 
> 
> > ali27":2cwabxfs said:
> ...



I was responding to your mention of a 24x18 granite surface plate.

If you wish to originate your own flat surface - good luck. I understand the theory, and have read a couple of accounts of just how much effort is involved. I have no plans to go there.

If you've read my pages on sole flattening, you'll know that I don't think scrapers are "the answer"

BugBear


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## ali27 (9 Dec 2010)

> The plate you show is far too small for lapping, and much bigger than you need for "reference flattening". To flatten any plane up to 22" (a #7) using the process I recommend, you only need a 12"x18" reference.
> 
> Indeed, if you use the method I recommend, the loading forces on the reference and dramatically lower than lapping, and the requirements for rigidity lower, so you could probably simply use your 10mm glass, taking the recommended precautions.
> 
> ...





> Bugbear, the floatglass plate I wrote about is actually smaller than the granite plate you suggest. If you mean longer ok, but a 12´´ by 18´´ granite plate is bigger than a 60cm by 10cm wide float glass plate.





> I was responding to your mention of a 24x18 granite surface plate.
> 
> If you wish to originate your own flat surface - good luck. I understand the theory, and have read a couple of accounts of just how much effort is involved. I have no plans to go there.
> 
> ...



I need to read more on the technique about creating 3 flats before I attempt it.

Bugbear, did you ever check the flattness of floatglass on your granite plate?

Ali


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## Vann (9 Dec 2010)

ali27":2z89dhzh said:


> What do you think about my idea of using several(3-5) plates of floatglass on top of each other to provide the necessary rigidity?


While I've not had experience with float glass, I can tell you that 4 sheets of 1/8" steel plate have nowhere near the rigidity of a sheet of 1/2" steel (i.e the same thickness). The effect will be the same for glass. 

I would estimate that 5 sheets of 10mm glass will be less rigid than a single sheet of 20mm glass.

But then I would estimate that 1 sheet of 10mm glass on a solid MDF base would be flat enough for what you need to achieve in a woodworking plane.

Cheers, Vann.


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## ali27 (9 Dec 2010)

Vann":27r5994u said:


> ali27":27r5994u said:
> 
> 
> > What do you think about my idea of using several(3-5) plates of floatglass on top of each other to provide the necessary rigidity?
> ...



Hi Vann,

It doesn´t sound right to me. My guts
say that you might be correct in that 5 sheets of 10mm glass will not have
the rigidity of 50mm floatglass, but I have the feeling it will be more rigid
than 20 mm glass.

To be honest, I don´t think MDF makes much difference. MDF probably
like all wood has low rigidity. I think a solid mdf base underneath 10 mm 
thick floatglass has the same rigidity as 12mm thick floatglass.

How is your plane passion going Vann? Hope your doing well.

Regards,

Ali


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## Vann (10 Dec 2010)

ali27":rzwks1qh said:


> How is your plane passion going Vann?


Hi Ali, 
It's seriously out of control. I have gathered heaps of old wrecks to do up (e.g. I have 15 Record 04s in various states of disrepair) , but only found time to do up two (and then to a low standard). And there's even less time to actually make shavings  

Ahh, the trials and tribulations of having a full time job and a young family.

Cheers, Vann.


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## bugbear (10 Dec 2010)

ali27":1lq2ft11 said:


> It doesn´t sound right to me. My guts
> say that you might be correct in that 5 sheets of 10mm glass will not have
> the rigidity of 50mm floatglass, but I have the feeling it will be more rigid
> than 20 mm glass.



Resistance to bending varies with inverse cube of thickness, all other things being equal.

So 20mm thick should be 8 times as stiff as 10mm thick. A simple stack of 10mm stack will increase stiffness linearly, so Vann appears to be correct.

BugBear


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## bugbear (10 Dec 2010)

ali27":2q7jxvtn said:


> To be honest, I don´t think MDF makes much difference. MDF probably
> like all wood has low rigidity. I think a solid mdf base underneath 10 mm
> thick floatglass has the same rigidity as 12mm thick floatglass.



Even assuming your MDF has infinite rigidity, if your floatglass is forced (by the load) to conform to the MDF surface, your flatness is now the flatness of the MDF, not the floatglass.

BugBear


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## ali27 (10 Dec 2010)

bugbear":2tljfupq said:


> ali27":2tljfupq said:
> 
> 
> > It doesn´t sound right to me. My guts
> ...



Thanks for the reply Bugbear. Very interesting. I need to read
more about this.

So, roughly how much stiffer would a 4 piece stack of 10 mm be compared 
to 1 plate of 10mm? Would it even make sense to do so or just get the 
thickest piece of float glass, 25mm is best in this regard.

I don´t know/understand how you calculated that 20 mm floatglass is 8times 
asstiff as 10mm, but I would guess then that 25mm thick glass is at least 
12 times as stiff?

Ali


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## ali27 (10 Dec 2010)

Vann":1s0av0ok said:


> ali27":1s0av0ok said:
> 
> 
> > How is your plane passion going Vann?
> ...



Vann, you need a plane detox my friend!

Ali


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## ali27 (10 Dec 2010)

Bugbear, 

Do you think a piece of 25mm thick floatglass(supported
with some newspaper) would be stiff enough to flatten a plane 
by the spotting(prussian blue) method? 

Floatglass is supposedly very flat and the spotting technique
does not put a lot of weight on the plate so it could work
quite welll, no?

Bugbear ,did you ever check the flatness of floatglass with
your granite surface plate?

Ali


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## studders (10 Dec 2010)

ali27":1o4ioqmh said:


> Bugbear,
> 
> Do you think a piece of 25mm thick floatglass(supported
> with some newspaper) would be stiff enough to flatten a plane
> ...



Depends what Newspaper it is and, what pages you use, page 3 would be no good at all. :wink:


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## ali27 (10 Dec 2010)

studders":df6durv1 said:


> ali27":df6durv1 said:
> 
> 
> > Bugbear,
> ...



:mrgreen: :mrgreen: 

Would the sports section of the newspaper provide enough support?

Ali


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## bugbear (10 Dec 2010)

ali27":2jbjghwe said:


> Bugbear,
> 
> Do you think a piece of 25mm thick floatglass(supported
> with some newspaper) would be stiff enough to flatten a plane
> by the spotting(prussian blue) method?



Before I got a surface plate, I flattened a #5 bailey plane using 6mm glass supported on router mat on a flattish support.

When I checked the plane, having got the surface plate, it didn't need any more work.

In your position, I would proceed with a single piece of 10mm glass, supported as recommend, and "see how you go".

I've never flattened anything bigger than #5.

A further practical hint - it may be best in the very early stages of a badly warped sole to use the "lapping" method, on any old flattish surface you have (e.g. MDF).

This will VERY rapidly remove the high spots, and you can then proceed with the prussian blue approach.

It's like planing (scrub-jack-jointer) or golf (drive, chip putt).

BugBear


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## ali27 (10 Dec 2010)

bugbear":2sqgukh9 said:


> ali27":2sqgukh9 said:
> 
> 
> > Bugbear,
> ...



Thanks for the advises Bugbear.

One more question about stacking floatglass for more stiffness. Now as you
wrote stacking seems not to increase stiffness very much. What about expoxying
the plates together. If I´d epoxy 3, 10mm plates. Would that give me the stiffnes
of a single 30mm plate?

Epoxying would probably worsen the flatness, but just wondering about
the stiffness.

Ali


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## Jacob (13 Dec 2010)

ali27":ufr0egox said:


> bugbear":ufr0egox said:
> 
> 
> > ali27":ufr0egox said:
> ...


Stiffness would be fine but with a laminate construction you could get distortion due to temperature differentials through the stack (think "bi-metal strip") specially if you are working hard on the grinding process and heating up the topmost plate. I'd suggest keeping the plate stack unglued and possibly lubricated, and to keep exchanging the topmost plate for a lower one, shuffle the stack as it were. It would also help to turn the plates top to bottom, end to end, to distribute and nullify any localised distortion.
Sharpening is not easy!

PS oh no we haven't got to sharpening yet. That's when things start really getting tricky :shock:


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## bugbear (13 Dec 2010)

Jacob":w599iqoi said:


> Stiffness would be fine but with a laminate construction you could get distortion due to temperature differentials through the stack (think "bi-metal strip")



That applies even for a solid reference. Indeed, for very high precision work (tenths and hundredths of thous), temperature control is critical. Even sunlight shining on the upper surface of a 4" granite plate can (ever so slightly...) warp it.



Jacob":w599iqoi said:


> specially if you are working hard on the grinding process and heating up the topmost plate.



Not an issue in this case - Ali isn't using the reference as a tool, only as a reference, keeping both loads and heat low.

BugBear


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## Dangermouse (4 Feb 2011)

Well my brain is spinning after reading all these posts. I try to keep things simple, being a simple Cornish country lad. You don't need to get the plane sole dead flat in an engineering sense, thats an impossible task anyway, just theory. The LN standard is 1.5 thou, the Clifton standard is 3 thou, around those figures is fine for any plane you use. If you can get a consistent 2 thou standard your ok. To get better would take a huge amount of work and time, not worth the effort. I use a slab of polished granite I got from my local stone mason, 32 inches long, 8 inches wide, 4 inches thick. Nice and flat to the tolerance needed, tested with my engineers straight edge. I paid all of a crisp fiver it and it will outlast me and never flex. Job sorted.
George


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## Jacob (4 Feb 2011)

Oh dear I see problems ahead. How will you stop such a long piece from flexing unless you can support it on another more solid flat surface? Daily temperature variations can be quite rapid and cause expansion at the surface. Perhaps keep it stored on end so that the ambient air will reach all sides evenly, on points of course, so that air will reach underneath. And turn it at intervals.
:shock: :lol: 

No it's OK really. Overkill, but only a fiver. A piece of mdf would have done. 
There is a lot of obsessive nonsense burbled about the flattening topic. 
The only important thing is to ask yourself whether or not your plane is performing well. Some people do more flattening/fettling than planing!


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## bugbear (4 Feb 2011)

Jacob":3jec61p8 said:


> There is a lot of obsessive nonsense burbled about the flattening topic.



Some people do make a lot of posts about it... 

BugBear


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## Dangermouse (4 Feb 2011)

I mainly use the granite to restore old planes with some rust on, I don't over do it too much. I like to get a nice clean surface. After all its nicer to use a well restored or mint condition plane than one thats a bit of a dog, :lol: , even if they do work as well as each other, or at least thats my opinion. Being an engineer i'm used to working to fine tolerances. But each to his own.


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## Benchwayze (6 Feb 2011)

12345678


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## James C (1 Apr 2012)

Jacob":kwfgq3vj said:


> ali27":kwfgq3vj said:
> 
> 
> > I see most guys are using about 10mm thick
> ...



I'm up for giving this a go. Do you have to have to pour white spirit all over the back of the paper or just work a small amount into it? Or is it better to pour a very small amount onto the table and then smooth the wet n dry over it?


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## Jacob (1 Apr 2012)

Just splash it onto the table and then onto the paper. It's better if you keep the paper between boards when not in use so that it stays flat. Paper backed, not cloth backed, which doesn't stay down so well


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## James C (1 Apr 2012)

Do I need a piece of wet n dry the same length as my plane? I want to sort my No7. I have wet n dry belts that fit onto the band sander but I think they must be cloth backed. The only definite paper backed stuff I have is 400 grit so probably too fine.


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## Eric The Viking (1 Apr 2012)

I haven't tackled my #7 yet! 

I wasted a lot of time and elbow grease doing my #4 and #5, simply by not going down the grits properly - starting with too fine a paper. In the latter case I realised I was being an silly person and switched, and the process didn't take too long at all. 

In both cases, the soles are now so flat that 'stiction' is a nuisance. I thought corrugated soles were a fad until that point! That said, when they're well lubricated, they will work really nicely.

Was it worth the effort? Dunno. My #4.5 and #7 haven't been flattened. The #4.5 still has the factory honing marks on it (my dad bought it and rarely used it), and the #7 is circa 1920. Both cut really well.

I think we worry too much, unless there are actual faults with the sole, for example hollows in the wrong places or concavity generally. 

Being able to sharpen well is a lot more important, and for that 10mm glass pretty much does everything I need.


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## Jacob (1 Apr 2012)

Any length will do. If it's short you adjust the pressure so its held down as it goes over the paper. As you would when planing. It's obvious when you do it.
Coarse is faster. NB you don't need to progress to finer papers if you keep the abrasion fore and aft lengthways and not across or diagonally (on the sole that is). The sole may look roughly sanded but it will soon lose the sharpness with a bit of use. Or you can accelerate this with a final pass over a fine paper - you only need to take the tops off the scratches, not to polish, it's not like finishing a piece of wood, you don't need the intermediate grades, you don't need to polish.

Corrugated or scratched soles can still be low friction - if the bits in contact with the wood are smooth themselves. You can have flat sole and low friction just using 60 grit alone - as long as you take off the sharpness, with use (and candle wax).




Eric The Viking":15g4yr2u said:


> .....
> I think we worry too much, unless there are actual faults with the sole, for example hollows in the wrong places or concavity generally. ......


Dead right - don't bother unless your journey is really necessary. Don't polish - completely unnecessary and a huge waste of time.


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## Jacob (3 Apr 2012)

Re. not polishing. I found this out by chance when I bought a new plane. The sole was flat but machine marked. In use it tended to track along the direction of the machining - which was fore and aft so so didn't matter much. I though I ought to polish it up a bit, but before I got round to it it had stopped tracking and appeared to be smooth even though the machine marks looked unchanged.
The explanation is simple. Scratches, pits, corrugations, whatever, are like ridges and furrows. To reduce friction you don't have to get down to the bottom of the furrows, you just need to take the sharp edges off the tops of the ridges and get them to the same height ("coplanar"). This will happen with use, or you can speed it up with fine paper.
This applies to chisel faces too. 
It follows that you can flatten a sole (if you have to) with say 40 grit paper, and then go straight to 200 grit (or finer) to "blunt" it and reduce friction, without going through the grades in between. 
All that polishing is pointless.


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## Eric The Viking (3 Apr 2012)

I beg to differ a bit on chisels: The mirror surface does let you get a better edge. My sharpening is improving, both in speed and quality, but I've only ever managed to get a 'dry shave' edge on chisels I've mirror-polished first. 

Obviously, it's a different objective with plane soles. 

Cheers,

E.


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## Jacob (3 Apr 2012)

Eric The Viking":rkpnzfju said:


> I beg to differ a bit on chisels: The mirror surface does let you get a better edge. My sharpening is improving, both in speed and quality, but I've only ever managed to get a 'dry shave' edge on chisels I've mirror-polished first.
> 
> Obviously, it's a different objective with plane soles.
> 
> ...


Well yes it needs to be clean immediately behind a sharp edge - press down a touch when removing the wire edge. But not the whole face.


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