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Lapping Plate?

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Forum topic by cut3times posted 01-11-2011 03:16 AM 3532 views 1 time favorited 14 replies Add to Favorites Watch
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cut3times

116 posts in 1754 days


01-11-2011 03:16 AM

Topic tags/keywords: lapping honing

Does anyone else have a lapping plate? I just got one and I have a few questions:

1. How do you store it (in a box, with oil/slurry left on it, etc.)
2. When lapping just a part of something like the back of a chisel, how do you keep from wearing the plate un-even since you cannot use the whole plate?
3. Have you had to flatten the plate itself and how did you do it?

Any help is appreciated
Jerry

-- And Still Too Short - "Life is what happens to you while you're busy making other plans." John Lennon


14 replies so far

View Steve Rathke's profile

Steve Rathke

26 posts in 2461 days


#1 posted 01-11-2011 04:30 AM

I have a granite one, i put it in a drawer, its easy to care for. if you have oil to deal with consider a tuper-wear like box. woodcraft has a chunk of granite thick, flat and big enough for a sheet of sandpaper. I lap with one and wet/dry sandpaper (grit 600 – 1000). It dosent wear, the paper does. Costs about $19 or so.

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cut3times

116 posts in 1754 days


#2 posted 01-11-2011 04:36 AM

Thanks Steve. I picked one of those up a year or so ago when they were on sale. I use it quite a bit. the lapping plate I got is from Veritas. It will be the next step after the granite/sandpaper.

Jerry

-- And Still Too Short - "Life is what happens to you while you're busy making other plans." John Lennon

View GaryL's profile

GaryL

1080 posts in 1578 days


#3 posted 01-11-2011 04:41 AM

I also have the granite plate. Check into the 3M Micro Abrasives. I just received some from Tools for Woodworking. This takes the sandpaper/Scary Sharp to a whole new level. I went all the way to .3 micron. Probably overkill, I think it’s equivilent to 15,000 grit…lol

-- Gary; Marysville, MI...Involve your children in your projects as much as possible, the return is priceless.

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Dan

3543 posts in 1628 days


#4 posted 01-11-2011 06:10 AM

I have a few pieces of plate glass that I use for lapping. I also just use sand paper. Only thing I have to do is clean the glass off when I change paper.

Gary- I have never tried the 3m Micro Abrasives but I think I will check into them. Right now the highest grit I use is 2000.

-- Dan - "Collector of Hand Planes"

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cut3times

116 posts in 1754 days


#5 posted 01-11-2011 04:50 PM

I also have PSA 5u, 0.5u and 0.3 non-PSA abrasives I use on plate glass. But as you know they ware out quickly. Plus trying to do a smoothing plane becomes a challenge. I have flattened a couple of smoothing and block planes using large plate glass (2’ x 3’) and sandpaper. My granite plate is too small. I am now hoping to get a super smooth sole on the planes using the lapping plate to reduce friction.

Jerry

-- And Still Too Short - "Life is what happens to you while you're busy making other plans." John Lennon

View ic3ss's profile

ic3ss

262 posts in 1525 days


#6 posted 01-12-2011 08:46 PM

I use a piece of scrap granite counter top that I got for free from a local counter top installer. I wrote a blog entry about it: http://lumberjocks.com/ic3ss/blog/18899

I would avoid stones, lapping plates and the like. For me, I want to make sure my lapping surface is dead flat always. With these you have to constantly check it and periodically flatten it out. I don’t have the time or money that I want to spend on these, so the granite base with sandpaper is the best alternative. I never have to check for flatness, I only have to scrape off and replace a piece of sandpaper. I can deal with that and it gives me the same results for the things we sharpen: chisels and plane irons. For me it just doesn’t make sense to spend a bunch of money on a lapping plate from Veritas, it’s too expensive.

-- "I am endeavoring, ma'am, to construct a mnemonic memory circuit using stone knives and bear skins."

View PurpLev's profile

PurpLev

8476 posts in 2396 days


#7 posted 01-12-2011 09:01 PM

to answer your question – I don’t think you can flatten the lapping plate you got unless you machine it on a metal grinder.

that said – since lapping does not really take a lot of material off but just smoothes out the surface of the metal I don’t think you nee to worry about the lapping plate getting out of true as it will not affect the flatness of your tools. since it only takes such a small amount of metal I think it’s unlikely that it’ll take a blade, or a plane sole out of flat ever.

enjoy.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

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cut3times

116 posts in 1754 days


#8 posted 01-12-2011 10:27 PM

Lev you get what I was trying to find out. I guess not many LJers do lapping. Everyone wants to get me to use glass and granite with sandpaper which I have been doing for years. I was hoping someone had done this before with a iron lapping plate. I believe what you stated it true. I guess time will only tell.

Jerry

-- And Still Too Short - "Life is what happens to you while you're busy making other plans." John Lennon

View richgreer's profile

richgreer

4525 posts in 1822 days


#9 posted 01-12-2011 11:50 PM

I don’t have a lapping plate, but my wife has a lap dog. Do you want her? (The dog – not the wife).

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

View Sawkerf's profile

Sawkerf

1730 posts in 1816 days


#10 posted 01-13-2011 12:23 AM

Lapping plates (or stones, etc) need to be harder than whatever is being lapped on them, or they will wear. The amount of wear will depend on the difference in hardness between the stone (or whatever) and whatever is being lapped.

My “lapping stone” is a piece of man-made counter top. When I tune up a chisel or plane iron, I spritz it with some water, lay down a piece of wet/dry sandpaper, spritz that with water, and go to work. As long as I don’t cut thru the sandpaper, the “stone” should last forever.

-- Adversity doesn't build character...................it reveals it.

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cut3times

116 posts in 1754 days


#11 posted 01-13-2011 12:45 AM

I think I need to post this picture to show what I have.

What you do is start with silicon carbide grit, let’s say 80, and coat the plate with it and mineral oil. You start your lapping process which starts breaking down the grit into finer grit. Theoretically the grit could end up 1000 or 2000 or finer depending on how long you lap the object. This produces a mirror finish on the object being lapped.

-- And Still Too Short - "Life is what happens to you while you're busy making other plans." John Lennon

View hokieman's profile

hokieman

166 posts in 2502 days


#12 posted 01-13-2011 05:02 AM

cut3times, thanks for the post. Where’d you get the lapping plate and how much did it set you back? Also, how fast does it cut to get it down to the mirror finish? I’m interested in learning more.

View BertFlores58's profile

BertFlores58

1646 posts in 1670 days


#13 posted 01-13-2011 05:17 AM

I was working on ship’s engine and lapping a lot of bucket valve plates…. The best way to correct the lapping plate… if it starts to deform…

TAKE A NEW GLASS (Thicker is better and wider than the lapping plate).

START BY COARSE LAPPING (Griding compound with oil or water) the glass against the lapping plate. You can now see the deeper part where the grinding paste have no effect.

FINISH WITH FINER Grinding compound and check with final chalk checking even erasures when using a wider new glass for lapping.

NOTE: the glass is very hard that the lapping plate will not be able to scratch it much. However the grinding compound will surely scratch it..

Hope this will help you.

-- Bert

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cut3times

116 posts in 1754 days


#14 posted 01-13-2011 04:14 PM

Hokieman look at post #2, there is a link to Lee Valley where I bought the plate. The lapping process can last an hour or two depending on the size and shape of what you are lapping.

Bert thanks. That makes sense because they talk about putting a Mylar sheet on glass, then putting oil and grit that adheres to the Mylar to lap some plane soles. The plate is just a large plane sole.

Jerry

-- And Still Too Short - "Life is what happens to you while you're busy making other plans." John Lennon

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