Best Lapping Compound Ever
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Clover. Readily available, Comes in a lot of different grits.
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17,083 Posts
It is an abrasive paste. Uses were described in Griff's post, two before yours. (To improve the fit.)
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17,083 Posts
Interesting. I would prefer to use water base if it were just as good - much easier to clean. Do you have any idea why the likes of Kraus has chosen to sell only grease-base? Pretty thick grease at that - it resembles (pure) lanoline in its greasy messiness and reluctance to be cleaned off, but it also has a solvent because it dries out easily.
Perhaps the grease is to provide better lubrication while the deed is being done in a fit that is rather tight - like a typical sax tenon use.
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Also, I use mine for flatting concave mouthpiece tables....using a sheet of glass as a surface table.
Not a clue as to the name of my carborundum paste....I have always had it, lives in the garage in it's double ended (fine & coarse) little rusty tin....very greasy.
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I have some Chemico Cleaning Paste which is OK. Perhaps slightly rough for some jobs. (Not to be confused with Chemico Grinding Paste).
Not that easy to find - I got mine delivered from the factory. Had to buy four tubs. I'm still working my way through the first one.
Not that easy to find - I got mine delivered from the factory. Had to buy four tubs. I'm still working my way through the first one.
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I think most lapping compounds have garnet as the abrasive. AFAIK it has the property of the larger, unwanted particles fracturing along crystalline planes when under excessive load, hence becoming a more appropriate size, rather making relatively deep gouges in the material.
Chemico possibly contains pumice powder as its abrasive, which would not have that property, with the risk that larger abrasive particles, under more load than the smaller ones, embed themselves in the surface of the metal. Then they are practically impossible to get out. Yamaha had this problem with a batch of student flutes a few years ago. The tenons and sockets became seriously scoured.
Lapping compound is typically used between components that have a very close and necessarily accurate fit. Larger abrasive particles among the smaller ones are definitely not what is wanted there.
Chemico possibly contains pumice powder as its abrasive, which would not have that property, with the risk that larger abrasive particles, under more load than the smaller ones, embed themselves in the surface of the metal. Then they are practically impossible to get out. Yamaha had this problem with a batch of student flutes a few years ago. The tenons and sockets became seriously scoured.
Lapping compound is typically used between components that have a very close and necessarily accurate fit. Larger abrasive particles among the smaller ones are definitely not what is wanted there.
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I'm not sure what is in Chemico. The website says it's silica.
"Composition: An aqueous paste combining vegetable soap and fine ground silica. Sodium carbonate provides mild alkalinity for cleaning whilst benzyl chlorophenol is a skin friendly preservative, also contains a germicidal additive."
The same company do produce a lapping compound but it seems ot be the greasy type.
http://www.chemico.co.uk/lappingpaste.html
Pumice powder is sold as lapping compound by Windcraft IIRC. It seem fine enough for most valve work.
"Composition: An aqueous paste combining vegetable soap and fine ground silica. Sodium carbonate provides mild alkalinity for cleaning whilst benzyl chlorophenol is a skin friendly preservative, also contains a germicidal additive."
The same company do produce a lapping compound but it seems ot be the greasy type.
http://www.chemico.co.uk/lappingpaste.html
Pumice powder is sold as lapping compound by Windcraft IIRC. It seem fine enough for most valve work.
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670 Posts
That's right! Carborundum is the name of a valve lapping paste meant for the purpose of lapping of auto valves to its seat. I have a similar set but in two plastic cans. Much to coarse in its original way to use for a supposed to seal metal - metal surface in any woodwind.
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I like the Musicmedic stuff. Choice of grits, comes in super small containers which I like since I go through it extremely slowly and it takes up less space and doesn't have time to dry out. The medium is crazy coarse, I barely ever use it. The fine works for most key fitting chores. The super fine is for when something is just baaaaarely binding and you don't want to overdo it.
http://www.musicmedic.com/catalog/products/abra-t100.html
http://www.musicmedic.com/catalog/products/abra-t100.html
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That is the very reason why, after about 30 years, the coarse has never been used...probably designed for lapping in ships' propeller trunnions.
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A wee small voice of my intuition says that the ideal lapping compound for steel may not be ideal for brass. That intuition may be incorrect.
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144 Posts
I just got some krafft fine valve grinding paste, for key fitting. It´s emery based (aka corundum or aluminium oxide) can be thinned with water, and warns that it can cause skin sensitisation.
It´s my favourite because it´s the only one I´ve got or tried, and replaces the previous technique of picking the grinding dust off the floor with an oily finger!
It´s my favourite because it´s the only one I´ve got or tried, and replaces the previous technique of picking the grinding dust off the floor with an oily finger!
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