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LV steel lapping plate too hard?

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ali27

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Hi guys, a while ago I bought a LV steel lapping plate. I sprinkle some
loose grit on it and flatten waterstones, backs of plane blades and the sole
of small planes. What I have noticed though is that the grit does not embed
in the steel, rather it rolls on the plate, no matter how hard I press. I was under the
impression that the grit would embed itself in the plate because the steel had a certain
softness.

Not sure how I should proceed now. Is there an easy way to soften the steel? I have
read a bit about this. One needs to heat up the iron to a very high temperature and then cool
it immediately and then warm it up again to soften it. Could I put the plate in boiling
water or very warm vegetable oil to soften it without the need of first having to heat
it up? I don't want a torch or something like that in my house.

Ali
 

Jacob

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If it was soft it would wear hollow with use and you'd have to flatten it. But you seem to like flattening so why not just stick the plate in the fire or something?
How's the woodwork? :lol:
 

ali27

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Jacob":2pn48wxg said:
If it was soft it would wear hollow with use and you'd have to flatten it. But you seem to like flattening so why not just stick the plate in the fire or something?
How's the woodwork? :lol:
Jacob I thought that if the metal has a certain softness, then the grit embeds in the steel
which actually prevents it from wearing hollow. If the steel is harder than this, then the
grit rolls around, which actually causes scratches and wearing hollow.

I do very little woodworking, I am trying to learn all skills so I can build a musical instrument.
It's a hobby thing.

Ali
 

GazPal

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ali27":1a9vupdq said:
Jacob":1a9vupdq said:
If it was soft it would wear hollow with use and you'd have to flatten it. But you seem to like flattening so why not just stick the plate in the fire or something?
How's the woodwork? :lol:
Jacob I thought that if the metal has a certain softness, then the grit embeds in the steel
which actually prevents it from wearing hollow. If the steel is harder than this, then the
grit rolls around, which actually causes scratches and wearing hollow.

I do very little woodworking, I am trying to learn all skills so I can build a musical instrument.
It's a hobby thing.

Ali

Sincerely and from a luthier's standpoint, if you wish to craft musical instruments your best bet is to focus upon skills that will benefit such builds. Namely choosing stock, materials manipulation, applying finish and each of the intermediate steps, rather than metalworking unless your intention is to craft woodwind, percussion or brass instruments, or make your own parts i.e. tuners.
 

Pete Maddex

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Hi, Ali

Is it this one http://www.leevalley.com/US/wood/page.a ... 3072,59752
If the grits did embed you would need on for each grit as they would contaminate the plate.
Are you using the grits with oil? it is only for final flattening not taking a lot of material off.

Don't heat it you will only warp it and render it unusable, well a paper weight.

Pete
 

JohnCee

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Using one of these to flatten waterstones doesn't seem like a terribly good idea to me. Surely you'll end up with coarser grit embedded in your stones?
 

Richard T

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I haven't used a lapping plate Ali but I'm sure yours is as hard as it is supposed to be. If it works precision flattening irons and soles - great. Not so sure about their use with flattening waterstones ... I wouldn't risk it.

NB; the way to soften hardened steel is to heat it thoroughly red (non magnetic) and let it cool slowly. Please don't!
 

Tony Spear

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LV say that their Lapping Plate is soft iron, and should not be used for flattening stones.

Dry abrasive is no good, you need an abrasive slurry basically oil/abrasive powder.

I've still got a tin of the old fashioned Grinding Paste from my messing about with old Motorbikes. It's got a lid each end, coarse in one and fine in the other.

If it's good enough for valve seating, it should be good enough for flattening blades and plane soles! :)

Further info here: http://www.timbecon.com.au/assets/files/05-M-2020.pdf
 

bugbear

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Jacob":ikhxcypw said:
If it was soft it would wear hollow with use and you'd have to flatten it.
You might want to look up any convenient reference on "lapping" as used by engineers.

You will (apparently) be surprised to find that it is a process where the softer of the two metals is worn away.

It's counterintuitive, which makes it interesting.

BugBear
 

ali27

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Guys you all make good points. Wiki gave me this info:

''Lapping is a machining operation, in which two surfaces are rubbed together with an abrasive between them, by hand movement or by way of a machine.
This can take two forms. The first type of lapping (traditionally called grinding), typically involves rubbing a brittle material such as glass against a surface such as iron or glass itself (also known as the "lap" or grinding tool) with an abrasive such as aluminum oxide, jeweller's rouge, optician's rouge, emery, silicon carbide, diamond, etc., in between them. This produces microscopic conchoidal fractures as the abrasive rolls about between the two surfaces and removes material from both.
The other form of lapping involves a softer material such as pitch or a ceramic for the lap, which is "charged" with the abrasive. The lap is then used to cut a harder material—the workpiece. The abrasive embeds within the softer material which holds it and permits it to score across and cut the harder material. Taken to a finer limit, this will produce a polished surface such as with a polishing cloth on an automobile, or a polishing cloth or polishing pitch upon glass or steel.''

http://en.wikipedia.org/wiki/Lapping

This following information comesin from LV instructions of this product:

Conditioning the Lap

As received, the lapping plate will need to be conditioned prior to first use. Conditioning coats the lap with a uniform film of oil and abrasive and beds some of the abrasive into the surface of the lap. This optimizes the time spent lapping and ensures uniform results. Conditioning is needed only when the lap surface is free of abrasive. The residual abrasive left on the lap from a previous session eliminates the need to recondition the lap (unless you are switching to a finer grit).
Is it possible LV made this plate accidentely too hard ? Cause I can't get the grit to embed
in the plate in a noticeable way. After having used the plate, I clean it with water and if I then feel the
surface of the plate, it feels almost completely smooth. So I tried the back of a plane blade
to see if there was indeed any grit embedded. Very fine lines were created which suggests
that there is some embedding, but way too little.

I knew that the plate was not designed to be used with water. I even contacted LV
and they told me the plate would rust and might change flattness. I don't mind that,
my problem is that the plate does not do what it's supposed to do. The grit doesn't
embed in the steel plate. When I first bought the plate, I used it with oil and silicone
carbide powder. I tried flattening the backs of plane irons and flattening a block
plane sole. The grit never really embedded in the steel plate and was moving around
like when one uses loose grit on a glass plate.

Ali
 

Pete Maddex

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Hi, Ali

Get in touch with LV see what they say
They say "Conditioning coats the lap with a uniform film of oil and abrasive and beds some of the abrasive into the surface of the lap"
So in normal use its coated with oil and abrasive, and after you clean it there is only some left, that sounds about right.
I think you are asking to much of it its for the final finishing not bulk metal removal try some wet and dry on glass. Its the way I flatten planes.

Pete
 

Jacob

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Thing is though nobody needed this stuff in the past but woodwork didn't seem to be diminished in any way. Why is this?
 

yetloh

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I too can confirm the efficacy of diamond paste, but Icertainly would not use it for flattening water stones. For that, you need something where the abrasive is captive and cannot contaminate the water stone. I my opinion, by far the best tool for that is the DMT 120grit continuous diamond plate. It is quick and highly effective.

As an alternative to water stones Derek Cohen's idea of making lapping plates for use with diamond paste from the soles of old broken Bailey planes is excellent, particularly for very hard modrn steels. The paste will embed well with limited wear to the plate but you do need one for each grade of paste. On the other hand, you could just use a filthy old dished oil stone like Jacob! :D

Jim
 

Jacob

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yetloh":amed14rs said:
... On the other hand, you could just use a filthy old dished oil stone like Jacob! :D

Jim
You may well larf - but it works! And fast and cheap. It's not that filthy. Grubby yes, but not filthy.
 

Derek Cohen (Perth Oz)

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Hi Ali

I've not used your lapping plate - too expensive to ship to Oz - so my thoughts are the result of reasoning , not direct experience with this tool.

Simply, the lapping plate you have is designed for loose diamond grit, not paste. In other words, the diamond is not meant to embed in the steel. It rolls loose and laps the cast iron or steel that runs over it.

That is likely why the steel is so hard - to actually prevent diamond embedding.

Now LV have just brought out mild steel plates specifically for diamond paste. They are an alternative to cast iron. I was involved with the pre-production testing, and I can confirm that these are excellent for diamond paste. These are intended for sharpening blades, not lapping the soles of planes, as is the plate you have.

http://www.leevalley.com/US/wood/page.a ... 72&p=69438

Regards from Perth

Derek
 

Tony Spear

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tim burr

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I agree with Jacob on this, surely the money that has been spent on all these lapping plates, diamond powders, pastes etc etc could have gone towards a plane that was flat enough to be fit for purpose in the first place and the obsessive amount of time spent flattening could actually go into making something. Without wanting to sound too harsh this instrument is going to be an heirloom by the time you get round to finishing it ! :shock:
 

ali27

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Hi Ali

I've not used your lapping plate - too expensive to ship to Oz - so my thoughts are the result of reasoning , not direct experience with this tool.

Simply, the lapping plate you have is designed for loose diamond grit, not paste. In other words, the diamond is not meant to embed in the steel. It rolls loose and laps the cast iron or steel that runs over it.

That is likely why the steel is so hard - to actually prevent diamond embedding.

Now LV have just brought out mild steel plates specifically for diamond paste. They are an alternative to cast iron. I was involved with the pre-production testing, and I can confirm that these are excellent for diamond paste. These are intended for sharpening blades, not lapping the soles of planes, as is the plate you have.

http://www.leevalley.com/US/wood/page.a ... 72&p=69438

Regards from Perth

Derek
Derek, I did not use diamond paste or powder, but silicone carbide powder. The
information given and in the instructions say that grit will embed and that one
doesn't need to put grit on the plate the next time one uses it. The problem is that
there is hardly any embedding at all.

If the steel plate is actually harder than the object being lapped, than what happens
is that the loose abrasive will actually embed in the softer object and lap the harder
object, which in this case would be the LV lapping plate.

Diamond paste, powder will actually embed in practically everything Derek. It will
even embed in glass which I know from experience. Glass is quite a bit harder than a soft steel. ''The lapping plate is made of soft iron and will wear over time''. That's what the LV instructions say.

Unfortunately I think LV had made this plate a bit too hard for it to be used
correctly with silicone carbide. The SiC doesn't embed very well. Diamond paste
/dust powder is probably the best thing I can use as diamond is much harder than
silicone carbide and will embed without any issues. Perhaps this could make a cheap
diamond lapping plate. Using 100 grit diamond paste or powder and pressing it in
the plate so it embeds in it.

Ali
 
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