floatglass as a surface plate thickness?

[ali27]

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

 

[hanser]

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.

 

[MickCheese]

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

 

[George_N]

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.

 

[ali27]

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

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

 

[Mooeee]

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.

 

[ali27]

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

 

[warrenr]

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

 

[studders]

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.

 

[Harbo]

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

 

[Jeff Gorman]

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

 

[Jacob]

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.

 

[GazPal]

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.

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.

 

[studders]

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.

 

[Alf]

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.

 

[bugbear]

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

 

[Jacob]

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!

 

[bugbear]

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.

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

 

[ali27]

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.

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

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

 

[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

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