Thread: Lapping Plates - Glass or Granite or somthing else?

Wait a minute, you used a dmt plate to flatten a certified
granite lapping plate? If that is whay you ''did'', then I am
sorry, but your granite lapping plate isn't flat anymore.

The certified lapping plate when new is very flat, flatter
than any diamond stone. A floatglass plate isn't as flat
as a certified plate, but it is flat enough for our purposes.

If I understood you correctly, I am sorry to say that you have
ruined your granite surface plate. Even if your diamond plate
had a better flattness than your granite plate, you couldn't
use it to make the granite plate even flatter because the diamond
plate is much smaller than the granite plate.

Sharpman

Originally Posted by SharpMan

Wait a minute, you used a dmt plate to flatten a certified
granite lapping plate? If that is whay you ''did'', then I am
sorry, but your granite lapping plate isn't flat anymore.

The certified lapping plate when new is very flat, flatter
than any diamond stone. A floatglass plate isn't as flat
as a certified plate, but it is flat enough for our purposes.

If I understood you correctly, I am sorry to say that you have
ruined your granite surface plate.

Sharpman

This is an old thread,

Anyway, it was a certified DMT to 0.0001". The granite plate was supposedly certified to the same range although it was visibly out. The certification that was provided was worth about as much as the paper it was stamped on. Luckily my DMT certification was a little more reliable.

A certification is only as good as the person who certified it, so i have learned. But i'm guessing you are aware of this as you know that my certified DMT isn't completely flat either, but my DMT was flatter then the granite at the time.

P.S. Its far from ruined and lapps perfectly now. I have tested several rulers and my certified DMT on the granite plate and they all show the granite being flat from all directions, also, as mentioned the granite plate isn't that much bigger then my DMT (10" x 3") and i used a glass plate that was much larger.

I take it you tried lapping something similar to know it doesn't work?

Brighty, Carba-Tec is having a sale 1-3 Dec.
That's where Pauly got his BMF lapping plate designed for use with powders.
FWIW

Originally Posted by Brighty83

This is an old thread,

Anyway, it was a certified DMT to 0.0001". The granite plate was supposedly certified to the same range although it was visibly out. The certification that was provided was worth about as much as the paper it was stamped on. Luckily my DMT certification was a little more reliable.

A certification is only as good as the person who certified it, so i have learned. But i'm guessing you are aware of this as you know that my certified DMT isn't completely flat either, but my DMT was flatter then the granite at the time.

P.S. Its far from ruined and lapps perfectly now. I have tested several rulers and my certified DMT on the granite plate and they all show the granite being flat from all directions, also, as mentioned the granite plate isn't that much bigger then my DMT (10" x 3") and i used a glass plate that was much larger.

I take it you tried lapping something similar to know it doesn't work?

From the DMT site:

With a consistent, aggressive diamond surface and precision ground, hand certified flat to +/- 0.0005”, the Dia-Flat™ Lapping Plate assures precise results when flattening stones. It's extra-large surface area makes it easy to use.

The diaflat is certified flat to 0.0005, not 0.0001. I am not sure, but I am guessing
that the steel plate on which the diamond are put has that flatness.

Did you use a certified straight edge to check for flatness? A standard ruler is not flat
enough to check these things.

You are correct in mentioning that certification by itself doesn't mean much. I would
advise you to use a certified straight edge to check the flatness of the plate if you
haven't already.

Of course I am hoping that you were succesful in making your granite
plate flatter, but I think the opposite unfortunately has happened.

Sharpman

Originally Posted by Havachat45

Brighty, Carba-Tec is having a sale 1-3 Dec.
That's where Pauly got his BMF lapping plate designed for use with powders.
FWIW

Thanks Geoff - i will have to see if my local one is too! Also, do you have a new bike?

Originally Posted by SharpMan

From the DMT site:

The diaflat is certified flat to 0.0005, not 0.0001. I am not sure, but I am guessing
that the steel plate on which the diamond are put has that flatness.

Did you use a certified straight edge to check for flatness? A standard ruler is not flat
enough to check these things.

You are correct in mentioning that certification by itself doesn't mean much. I would
advise you to use a certified straight edge to check the flatness of the plate if you
haven't already.

Of course I am hoping that you were succesful in making your granite
plate flatter, but I think the opposite unfortunately has happened.

Sharpman

Your are correct, mine states "Hand certified flat to: less then +\- 0.0005"



But i am generally happy when i can place two stones on top of each other with a small a mount of water, lift them just off the table by the top stone and have them stick together. If no air get in between to make them fall apart i know they are close enough, or closer then what is required. if they come apart after a few seconds i know there is a concave or a convex. So far, no stone i have ever received out the box has ever passed this test but they always pass after they are lapped.

As mentioned previously in this thread, they don't need to be 100% flat but if you get get them close to 100% its not a bad thing. Flattening the granite with the glass alone should achieve this.

[QUOTE=Brighty83;881192]Thanks Geoff - i will have to see if my local one is too! Also, do you have a new bike?


I have two, Brighty, one K and one R - love them both.
It might be worth PM'ing Pauly to see if he can give you the details of his lapping plate.
He bought it around and lapped my hones for me and it did a fine job - even on the PHIG

So what i don't understand is, I'm told i have destroyed my granite plate that wasn't flat before lapping. I have been using for the last couple of months after lapping it with no troubles.

Through out the thread, the no.1 statement is "it dosnt need to be 100% flat"

I lapped it first with my DMT to get the majority flat and then finished with my glass plate that is much larger then the granite plate, and as noted on here, the glass plate by it self is more then flat enough to lapp a hone (as mentioned previously). The granite plate was noticeably out before lapping it now its, as far as i can tell 100% flat (or 99.9% flat)

Now, this plate will go out and am i supposed to through it out or why isn't it ok to maintain it the way i have, since i seem to be able to get it flat via this method. according to the comments, this plate cant be maintained and once lapped its worthless. I really think that, by saying that, the comments are miss leading people.

I'm very OCD about everything i do and if its not 100% im not happy. I just cant see how it can be decided that its not flat and that i destroyed it when no once has checked it after.

Dose this mean i need to re lapp all my hones now?



If that's the case, i have a lot of work on my hands

Originally Posted by Brighty83

So what i don't understand is, I'm told i have destroyed my granite plate that wasn't flat before lapping. I have been using for the last couple of months after lapping it with no troubles.

Through out the thread, the no.1 statement is "it dosnt need to be 100% flat"

I lapped it first with my DMT to get the majority flat and then finished with my glass plate that is much larger then the granite plate, and as noted on here, the glass plate by it self is more then flat enough to lapp a hone (as mentioned previously). The granite plate was noticeably out before lapping it now its, as far as i can tell 100% flat (or 99.9% flat)

I'm very OCD about everything i do and if its not 100% im not happy. I just cant see how it can be decided that its not flat now when no once has checked it after.

Brighty, the thing is that to check the flatness of the granite plate, you would
need something that is flatter than the plate itself. You used the diaflat as reference
which has a certified flattness of 0.005 whereas the granite plate should be even
flatter than that. It doesn't make sense to use something that is (supposedly) less
flat(Diaflat) to check something that should be flatter(granite plate). What you need
is a certified flat straight edge.

There is a 99.9% chance that you have reduced the flatness of the granite plate. Now from
your post I read that you were going to use abrasive powder with this plate. Well the abrasive
powder would have destroyed the flattness as well. The abrasive would have grinded away
the plate as well. Tiny amounts each time of course. But everytime you would have used it
this way would result in less flattness.

Now you don't need a certified granite plate for your purpose. It's
fun, but overkill. A 10mmthick floatglass plate is all you need. I
would advise you to buy this and also buy the thinnest floatglass
that is available in the same size as the 10mm thick floatglass.
Put the the thin plateon top of the 10mm plate and use the abrasive
powder on the the thin plate. Whenever you seethat the thin plate
has lost its flatness, discard it. There is a chance you might get the the thinfloatglass plate for free.

The 10mm floatglass will cost you about 5-10bucks. The 10mm plate s
upportsthe upper thinner plate so it won't(reduces significanly)
bend/deflect when you put pressure on it.

Not sure how much you payed for the granite plate, but don't
worry about it. It's probably still flat enough for your purpose.
If you still really want to know how flat it is, you can buy a good
certified straightedge and feel gauges. The feeler gauges are very
thin pieces of metal which you push under the ruler and the object
on which the straightedge is put on. The feeler gauges have a
certain thicknes so you can see how much certain areas are
higher or lower than they should be. A set of feeler gauges is cheap
5 bucks or so. A good certified straigtedge costs about 30-300
bucks depending on size, metal, flatness.

As for the OCD you talk about, my advice relax dude. It's all for
the fun. Forget about stones, flattness and concentrate on more
important stuff. It's just not worth it IMHO.

Sharpman

Originally Posted by Brighty83

So what i don't understand is, I'm told i have destroyed my granite plate that wasn't flat before lapping. I have been using for the last couple of months after lapping it with no troubles.

Through out the thread, the no.1 statement is "it dosnt need to be 100% flat"

I lapped it first with my DMT to get the majority flat and then finished with my glass plate that is much larger then the granite plate, and as noted on here, the glass plate by it self is more then flat enough to lapp a hone (as mentioned previously). The granite plate was noticeably out before lapping it now its, as far as i can tell 100% flat (or 99.9% flat)

Now, this plate will go out and am i supposed to through it out or why isn't it ok to maintain it the way i have, since i seem to be able to get it flat via this method. according to the comments, this plate cant be maintained and once lapped its worthless. I really think that, by saying that, the comments are miss leading people.

I'm very OCD about everything i do and if its not 100% im not happy. I just cant see how it can be decided that its not flat and that i destroyed it when no once has checked it after.

Dose this mean i need to re lapp all my hones now?



If that's the case, i have a lot of work on my hands

Nice Collection.

Originally Posted by Havachat45

I have two, Brighty, one K and one R - love them both.
It might be worth PM'ing Pauly to see if he can give you the details of his lapping plate.
He bought it around and lapped my hones for me and it did a fine job - even on the PHIG

Thanks, I want a new bike but the fiancee wont allow it..

I have enough lapping stuff to keep me going for a while but if they have a sale on I'm sure there is something else i can pick up from there