granite plate price, take it?

A week or so ago I started a topic about needing a long
narrow surface plate. A dutch company offered one
size 85cm long, 17cm wide and 6.5cm thick. Price total
171 euro.

After some persistence(you guys know by now that I am persistent)
I got an email saying they would give me a 50% student discount.

The price should be roughly 90 euros for this plate. According to
them it is 120 euros. I sent them an email showing how they
have miscalculated it. I will wait for their response.

Anyway the plate is accuracy DIN 876/0. (7,0 µ). Is it a good
deal guys? 90 euros for this plate? Quite a bit of money, but
it is what I am looking for.

I also tried buying the book that was recommended to me
´´Foundations of mechanical accuracy´´, but man that book
is almost not te be found and 100-500 USD for a book is way
over my budget. Tried finding it as pdf file or so, no luck.

Flatman

So what was the problem with the Ebay link for the one at $30 + shipping? You couldn't get it any cheaper than this?

The book you mention, by Moore I believe, is a definitive reference document on the topic, expensive yes, will you use it forever, yes again, well worth the investment.

flatman28 said:

A week or so ago I started a topic about needing a long narrow surface plate.

Click to expand...

Yeah, but you needed it to sand plane soles. In a subsequent thread you said you decided not to sand them, and instead scrape them.

So, since you don't need it, it doesn't seem like a good investment.

He's gonna need some kind of reference to scrape the planes to.

Mike C. said:

So what was the problem with the Ebay link for the one at $30 + shipping? You couldn't get it any cheaper than this?

Click to expand...

The plate is too small. The diagonal is 15´´. I want to flatten jointer
planes as well. Also shipping,handling and taxes make it almost as expensive
as the plate I am considering to buy.

jkilroy said:

The book you mention, by Moore I believe, is a definitive reference document on the topic, expensive yes, will you use it forever, yes again, well worth the investment.

Click to expand...

Perhaps somewhere allong the road cause now I can´t. I will keep looking for
a free pdf somewhere, lol.

mark thomas said:

Yeah, but you needed it to sand plane soles. In a subsequent thread you said you decided not to sand them, and instead scrape them.

So, since you don't need it, it doesn't seem like a good investment.

Click to expand...

Hi Mark. I still need a surface plate. Since the cheapest surface plates which
would do an adequate job, is about the same price as this one that I mentioned, I
wouldthink that buying that thing long one would be a better choice. Also could use
this long one to make long straightedges.

The company writes this about their granite plates:

´´MYTRI uses Fine Black Granite as their standard. This granite has a very fine-grained structure and is homogeneous with grain-size below 1 mm. Normal black, grey or pink granite have a grain-size of 2-3 mm. The hard crystals of normal granite are rough, the twined spaces weak and porous.

DURABILITY
The high homogeneity of Mytri Fine Black Granite (density 20% higher than normal granite) results in a hardness wherever measured (6,5 - 7 according to Mohs’ scale). The high homogeneity of Fine Black Granite guarantees longevity and the highest conceivable degree of accuracy and flatness.

Mytri Fine Black Granite is twice as good as normal granite, due to the directional crystal within the granite, thus giving a high bending strength.
To obtain the same bending-strength as normal granite, the plate would
need to be 44% thicker. Fine Black Granite is fundamentally insensitive to mechanical overloading.

CHEMICAL CHARACTERISTICS
The absorption of humidity of Fine Black Granite is as half as much than of normal granite.´´

Seems like a real sales pitch, but I don´t know.

The accuracy is DIN 876/0. (7,0 µ). What grade is this?

Flatman

A plate with a 15" diagonal can flatten a plane up to about 36", once you get the hang of what you are doing. You can easily learn to achieve a flat surface with smaller planes on this smaller plate and then work up to doing the larger ones. That's why I posted the link. Good luck.

Mike C. said:

He's gonna need some kind of reference to scrape the planes to.

Click to expand...

I meant he doesn't need a long skinny plate, since a $20 9"x12" would meet scraping needs.

flatman, if this plate costs the same as a $20 plate with shipping, then it makes sense. But you might also ask this company if they have something smaller and cheaper.

That plate is also pretty thin, relative to most surface plates (33"x6"x2.5".) Plates with one dimension 18" long are usually 3" thick, and 36" long are 4" thick. If this plate is 876/0, I would trust that it's flat, but be cautious that it's probably a bit more fragile than things like 9"x12"x2", or 12"x18"x3" (standard US sizes). Don't drop it!

Curious.......why do you think you need a machinists surface plate to flatten a woodworking hand plane? Am I missing something? Is this just because you want to scrape in planes, or because you think you need to?

Jeff

Mike C. said:

A plate with a 15" diagonal can flatten a plane up to about 36", once you get the hang of what you are doing. You can easily learn to achieve a flat surface with smaller planes on this smaller plate and then work up to doing the larger ones. That's why I posted the link. Good luck.

Click to expand...

I had read about using smaller plates to flatten bigger
planes, but it makes it more difficult.

mark thomas said:

I meant he doesn't need a long skinny plate, since a $20 9"x12" would meet scraping needs.

flatman, if this plate costs the same as a $20 plate with shipping, then it makes sense. But you might also ask this company if they have something smaller and cheaper.

That plate is also pretty thin, relative to most surface plates (33"x6"x2.5".) Plates with one dimension 18" long are usually 3" thick, and 36" long are 4" thick. If this plate is 876/0, I would trust that it's flat, but be cautious that it's probably a bit more fragile than things like 9"x12"x2", or 12"x18"x3" (standard US sizes). Don't drop it!

Click to expand...

Mark, 2.5 inches thick is still a lot thicker than 1cm
thick floatglass

I definitely need to be careful with it. Perhaps make
some sort of box where I can put it in which also
gives support to it.

hawkfan9 said:

Curious.......why do you think you need a machinists surface plate to flatten a woodworking hand plane? Am I missing something? Is this just because you want to scrape in planes, or because you think you need to?

Jeff

Click to expand...

I am not sure whether I need it to be honest. I do
want to learn scraping planes flat. I am not sure
whether or not I need a granite surface plate for
it. Maybe an inch thick float glass would be good
enough for scraping since its ''flat'' and rigid
enough(not for lapping)

Don't know about the flatness of floatglass though.
Some say it is close to B grade surface plate. I don't
know. Putting a piece of floatglass on a surface plate
would answer that, but I have not seen anybody do
that.

I do know that I have seen a plane being lapped
on 3/4 inch floatglass and this plane was taking
very thin shavings, full width. Since scraping is
more accurate, I guess it would give even better
results, so probably a thick piece of floatglass
is good enough.

Flatman

You still have not grasped the concept that smooth is not always flat. Glass is kind of flat, a surface plate (even grade B, which will be fine for your uses) is EXTREMELY FLAT, though not as smooth as glass. Putting a piece of glass on a surface plate is counter-productive. Might as well lay the glass on a tabletop. The value of the flatness of the surface plate will be lost on the waviness of the glass. If you insist on using glass, bed it on a board with automotive body filler and be done with it.

Using the smaller plate to flatten the longer plane will not, in fact make it more difficult, it will just require careful attention to what you are doing. Once you understand the basic concept of scraping, it will be obvious that this is not, in fact, difficult at all.

http://www.angrave.com/catalog/SurfacePlates.html

Read and learn what a grade B plate is all about. It's still light years ahead of a piece of plate glass, which has no minimum surface grade requirements.

Mike C. said:

You still have not grasped the concept that smooth is not always flat. Glass is kind of flat, a surface plate (even grade B, which will be fine for your uses) is EXTREMELY FLAT, though not as smooth as glass. Putting a piece of glass on a surface plate is counter-productive. Might as well lay the glass on a tabletop. The value of the flatness of the surface plate will be lost on the waviness of the glass. If you insist on using glass, bed it on a board with automotive body filler and be done with it.

Using the smaller plate to flatten the longer plane will not, in fact make it more difficult, it will just require careful attention to what you are doing. Once you understand the basic concept of scraping, it will be obvious that this is not, in fact, difficult at all.

http://www.angrave.com/catalog/SurfacePlates.html

Read and learn what a grade B plate is all about. It's still light years ahead of a piece of plate glass, which has no minimum surface grade requirements.

Click to expand...

Mike,

I think you have misunderstood my post. I wasn't very
clear.

I am aware of the difference between smooth and flat.
That is why I wrote glass is ''flat''(relatively).

By putting a piece of floatglass on a surface plate(with prussian blue which I forgot to mention) and then checking how flat floatglass actually is. I have never seemn anybody do this.

Some people mention floatglass is very flat and give some numbers, but nobody has put it on a surface plate(with prussian blue) to check really how flat it is. Well I am sure some people have done it, but have never seen pictures of it.

I did not mean putting the glass on the surface plate and then using it as a surface plate.

Even if a piece of floatglass would be very flat, that does
not mean another piece will be as well. It's not certified, I know.

Flatman

OK, that makes more sense.

I think the basic point is that, if you have a surface plate to see if the glass is flat, you don't need a piece of flat glass, lol. As you note, just because that particular piece of glass is flat does not mean the one laying right beside it is. Also, the very flatness of the surface plate will help out a thin, bowed piece of glass to some extent as the glass will lay more relatively flat on the nice flat plate.

You are just over-thinking this, man. Get that $20 plate and get to scraping and decide after that if you need a longer plate. I am prone to do the same thing. I'll research something to death before I just have at it. I find that just jumping in and starting is the hard part.

Mike C. said:

OK, that makes more sense.

I think the basic point is that, if you have a surface plate to see if the glass is flat, you don't need a piece of flat glass, lol. As you note, just because that particular piece of glass is flat does not mean the one laying right beside it is. Also, the very flatness of the surface plate will help out a thin, bowed piece of glass to some extent as the glass will lay more relatively flat on the nice flat plate.

You are just over-thinking this, man. Get that $20 plate and get to scraping and decide after that if you need a longer plate. I am prone to do the same thing. I'll research something to death before I just have at it. I find that just jumping in and starting is the hard part.

Click to expand...

I think you are correct. I definitely need to just jump in.

But Mike, the thing is that 20 dollar plate will be about
a 100 hundred dollars when it arrives at my home. Shipping costs(at least 50 dollars or so)+ taxes(19%value of product+shipping cost) and it's already a hundred dollars.

Flatman

flatman28 said:

I do know that I have seen a plane being lapped
on 3/4 inch floatglass and this plane was taking
very thin shavings, full width. Since scraping is
more accurate, I guess it would give even better
results, so probably a thick piece of floatglass
is good enough.

Flatman

Click to expand...

There is not a whole lot of discussion of flattening plane soles in woodworking circles because it is so easy to do.

Most move on the the more pithy topic of getting boards flat and straight as this is where the real challenge lies.

I used to place a indicator on a board as it was coming out of the planer and joke with clients that I had to let it "rest" between cuts before I could proceed. Billable time of course... the indicator dial would never stop moving..

If you are really invested in learning how to scrape a surface to precision by all means proceed. Just remember that the heat generated by working the tool will wreck the last thou you labored over trying to get the thing "flat" by machinists standards while the wood dances out of line by tenths before your eyes.
If you just want to pull out come camber or twist in your plane sole- look around your home and find some "flat" surface and lap the plane sole on that. Then move on to getting the iron sharp and setting up a decent bench with good vises etc.

Woodworking is a hoot but there is a reason you don't see a lot of surface plates in cabinet makers shops.

flatman28 said:

A week or so ago I started a topic about needing a long
narrow surface plate. A dutch company offered one
size 85cm long, 17cm wide and 6.5cm thick. Price total
171 euro.

After some persistence(you guys know by now that I am persistent)
I got an email saying they would give me a 50% student discount.

The price should be roughly 90 euros for this plate. According to
them it is 120 euros. I sent them an email showing how they
have miscalculated it. I will wait for their response.

Anyway the plate is accuracy DIN 876/0. (7,0 µ). Is it a good
deal guys? 90 euros for this plate? Quite a bit of money, but
it is what I am looking for.

I also tried buying the book that was recommended to me
´´Foundations of mechanical accuracy´´, but man that book
is almost not te be found and 100-500 USD for a book is way
over my budget. Tried finding it as pdf file or so, no luck.

Flatman

Click to expand...

€90 for a new surface plate 85x17cm you call quite a bit of money
Thats dirt cheap
Also don`t expect that to be straight in all positions you lay it in
Only supported the proper way it will meet specs
Another question
Is your planer stiff enough to stay that flat when using it The forces acting on it while using it will probbably bent it way more as the additional accurracy you gain by using a surface plate above another piece of flat you have at hand

Peter from holland

peterve said:

€90 for a new surface plate 85x17cm you call quite a bit of money
Thats dirt cheap
Also don`t expect that to be straight in all positions you lay it in
Only supported the proper way it will meet specs
Another question
Is your planer stiff enough to stay that flat when using it The forces acting on it while using it will probbably bent it way more as the additional accurracy you gain by using a surface plate above another piece of flat you have at hand

Peter from holland

Click to expand...

Good advise Peter.

I don't know about the stiffness of my plane. There is nothing
I can change about that.

What I am certain about is that my planes' soles aren't flat and
this is affecting its performance.

The same plane I am using, is also used in this vid:

YouTube - Rob Cosman's "The $20 Lie-Nielsen"

And this Mr is making much better shavings then my plane.
The other parts of my plane are tuned perfectly. The sole
is just really out of flat.

Peter,die vlakplaat is niet duur Peter, maar geld is een probleem
voor mij op het moment en dan is bijn alles duur

Groetjes

Flatman

Trboatworks said:

There is not a whole lot of discussion of flattening plane soles in woodworking circles because it is so easy to do.

Most move on the the more pithy topic of getting boards flat and straight as this is where the real challenge lies.

I used to place a indicator on a board as it was coming out of the planer and joke with clients that I had to let it "rest" between cuts before I could proceed. Billable time of course... the indicator dial would never stop moving..

If you are really invested in learning how to scrape a surface to precision by all means proceed. Just remember that the heat generated by working the tool will wreck the last thou you labored over trying to get the thing "flat" by machinists standards while the wood dances out of line by tenths before your eyes.
If you just want to pull out come camber or twist in your plane sole- look around your home and find some "flat" surface and lap the plane sole on that. Then move on to getting the iron sharp and setting up a decent bench with good vises etc.

Woodworking is a hoot but there is a reason you don't see a lot of surface plates in cabinet makers shops.

Click to expand...

Actually the topic on flattening planes is something I see
quite regurarly on woodworking fora.

How many woodworkers check the flattnes of their sole
with a straightedge or use a surface plate for this? They
don't usually.

They just buy some floatglas or mdf and stick some abrasive
paper on it and work on it for hours.Eventually they either
give up or think it is flat(no proof).

Flatman

I presumed you had a long 70cm planer or so as you wanted a 85cm long surface plate
The shaper like on the movie is not even 30cm long
If you have the same one why do you need a 85 cm plate
And those short planers are pretty sturdy and would not flex that much
The flexing I talked about was for a 70 cm or longer one
Just get yourself some ground stock the lenght of your planer and 25mm thick or more
Go visit the scrapyard

Peter from holland

This discussion is going round and round and round... what recent posters don't realize it that this discussion is spread across several threads that flatman started. The issue of what's flat enough, the length of flatman's planes, how large a surface plate he needs, his budget, etc. etc. etc. etc....

I believe every one of flatman's questions has been answered, at least twice.