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Thread: Lapping

  1. #16
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    Ok, some development on my quest to get this #7 flattened...

    I had to take a course for work today and it led me through an industrial part of town. I noticed a stone benchtop dealer on the way.

    I stopped by on my way home from work. He had a great piece which is about a meter long and 150mm wide. AU$20. Sold.

    It's 20mm thick solid quartz, so it's rigid without any support. I also asked him to explain how he knew that it was "dead flat".

    He explained to me that, after granite is cut with a large, water cooled saw, it is run through some kind of gauntlet-like series off water-cooled precision surface grinders of progressively finer grit. If there is any undulation at all remaining, it is run again. As we all know, stone countertops exhibit a beautiful, polished sheen for many many years. If they were not ground and polished to an impeccably flat surface, then they would not have that appearance and would not be desirable for sale as kitchen benchtops.

    Next order of business is to get some adhesive-backed sandpaper... I will make further updates when I can.

    Cheers,
    Luke

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  3. #17
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    OK! Last post from me unless questioned.

    See my previous post. I got the cheap slab of quartz countertop. It's 1250mm long and 150mm wide. I reckon this is the absolute perfect size. I will explain why shortly...

    It fit perfectly between my widest bench dog setting, which was nice. I decided to just use non-adhesive paper (80 grit) and contact adhesive. It was the same price for 5m of this stuff and an aerosol bottle of adhesive as 4m of adhesive-backed from ebay, and it was right down the road at The Big Green Shed (D.W. - that's a nickname for the Aussie version of Lowes/Home Depot).

    I retracted the blade and set to work. The width of the slab is almost perfect for the 115mm wide sandpaper. Given the length, I was able to take full length strokes with the #7, hence my comment about the perfect length.

    All in all it took about five minutes to lap the 7 with the corrugated sole (technically a 7C). I then sharpened up and was immediately able to get full width, super fine shavings. The initial problem was that I had to advance the blade unreasonably far to get a shaving at all, and when I finally did, it tended to be far more coarse than desired. Completely fixed.

    Here's a shot of it. Sorry, the bright white of the quartz tricked the phone into thinking I was photographing the sun or something...

    image1(2).jpg

    Cheers to everyone for the ideas and help along the way. This method comes highly recommended and cost me $20 plus $20 in consumables which I can use to lap at least four more planes.

    Luke

  4. #18
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    I was lapping a #4 and #4 1/2 the other day just using my wetstones. It sort of worked, but not good enough imo. They r too short. I figure ill do something similar with granite. I have considered using my panel saw table which is dead flat....but it will get abrasive dust all over it and scratch it.

    Does that granite flex at all? because my workbench has bumps in it

  5. #19
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    Quote Originally Posted by Kuffy View Post
    Does that granite flex at all? because my workbench has bumps in it
    I felt no flex whatsoever. I would imagine if you put it on two saw horses or some equally as foolish setup where it was only supported at the ends it might. Or it might be brittle enough to just outright break. But, believe me, my bench is absolute garbage. If there's a bumpy bench in Queensland it's this one, and I had fantastic results. I'd say if you go for something in the 20mm range you'll be happy. If you're in the Brisbane area I can recommend a place (PM me).

    Cheers,
    Luke

  6. #20
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    Quote Originally Posted by Luke Maddux View Post
    OK! Last post from me unless questioned.

    See my previous post. I got the cheap slab of quartz countertop. It's 1250mm long and 150mm wide. I reckon this is the absolute perfect size. I will explain why shortly...

    It fit perfectly between my widest bench dog setting, which was nice. I decided to just use non-adhesive paper (80 grit) and contact adhesive. It was the same price for 5m of this stuff and an aerosol bottle of adhesive as 4m of adhesive-backed from ebay, and it was right down the road at The Big Green Shed (D.W. - that's a nickname for the Aussie version of Lowes/Home Depot).

    I retracted the blade and set to work. The width of the slab is almost perfect for the 115mm wide sandpaper. Given the length, I was able to take full length strokes with the #7, hence my comment about the perfect length.

    All in all it took about five minutes to lap the 7 with the corrugated sole (technically a 7C). I then sharpened up and was immediately able to get full width, super fine shavings. The initial problem was that I had to advance the blade unreasonably far to get a shaving at all, and when I finally did, it tended to be far more coarse than desired. Completely fixed.

    Here's a shot of it. Sorry, the bright white of the quartz tricked the phone into thinking I was photographing the sun or something...

    image1(2).jpg

    Cheers to everyone for the ideas and help along the way. This method comes highly recommended and cost me $20 plus $20 in consumables which I can use to lap at least four more planes.

    Luke
    If you have a good straight edge and feeler set, check it anyway. There are a lot of polished pieces of granite and quartz around here that still need to be flattened (it's something you can do, though).

    At 20mm, it will still flex some if it's not supported under the middle (but if you put it on a bench, no problem).

    It doesn't have to be perfect, either (i'm not advocating the notion that it can't be used if you can pass a couple thousandths of feeler under a straight edge somewhere on it), but it's nice to know what you've got before you start.

    Also, an apparatus that is mildly hollow can still be used to create a flat surface just by technique overlapping the edge some while lapping. Same as you can use a slightly dished finish stone and still not have a problem with it sharpening flat irons, etc.

    (good deal, by the way, finding something relatively inexpensive. Early on, I got a piece of 12x18 custom tempered float glass and it cost me $90. I didn't know any better. I still haven't dropped my much more handy-to-use non-tempered glass shelf that cost $20. It creates a riddle, I guess - what do you do with a $90 piece of glass that's got a couple of chips on one corner? I don't know an answer other than to slide it behind a shelf so that you don't see it and get disgusted!!).

  7. #21
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    Quote Originally Posted by D.W. View Post
    If you have a good straight edge and feeler set...
    D-Dub,

    I've seen you mention feelers a few times, and you've mentioned them in your videos. I suppose it's about time I bit the bullet and just asked this...

    What is a feeler? I'm imagining some kind of very small item that you slide in between your straight edge and the reference surface to gauge the gap. Am I on the right track? I feel like I need to be switched on to how to actually measure thousandths of an inch if I'm going to be part of the crowd which dwells on them (which I already am...).

    Cheers,
    Luke

  8. #22
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    In hindsight I should've just googled feeler set. I see what it is now.

    I suppose this is an entirely different topic, but...

    If I want to buy a feeler set, do I need to spend much money on it? It looks like I can get one for about 8 bucks. You think it would do the trick?

    Cheers,
    Luke

  9. #23
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    Quote Originally Posted by Luke Maddux View Post
    In hindsight I should've just googled feeler set. I see what it is now.

    I suppose this is an entirely different topic, but...

    If I want to buy a feeler set, do I need to spend much money on it? It looks like I can get one for about 8 bucks. You think it would do the trick?

    Cheers,
    Luke
    I'd go cheap if this is all you'll use it for. Sometimes, the cheap sets aren't very accurate, but for what you're doing, you just want a very thin metal shim, thinner than a sheet of paper to check.

    Your other option is to get a high quality feeler but only one size, and couple that with office paper or other things of known thickness.

    Anyway, if you get one and it's mislabeled like my cheap one, you can still tell which one's the thinnest because the thin ones are very flexible with the resistance to flexing determined by the thickness of the feeler. I can tell that my thinnest gauges (which are mislabeled, but the set says that it goes down to .0012") are a lot thinner than a sheet of paper and that's really all I'm looking for.

  10. #24
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    Somewhere like supercheap auto, autobahn, Mitre 10, or bunnings will ha e feeler gauges.
    Glenn Visca

  11. #25
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    Luke - try Autocheap or Repco, whichever is closest to you. I bought my last set at Repco and according to my friend's good quality micrometer, they are within a reasonable percentage of stated thickness. But as DW says, you really don't have to have them spot-on for the purposes you're talking about. However, this raises another conundrum - unless you have spent a fair amount on your straight-edge, and it is definitely & reliably straight to within very tight tolerances, you won't know if you are detecting inconsistencies in that, or your slab.......

    Personally, I wouldn't bother. You have got your plane working nicely, so the slab is obviously flat enough for purpose. Feeler gauges are essential kit for engineers & mechanics, and very occasionally handy in the woodshop, but they have very little application to most woodworking-related activities. One of the very few times for me was when I was trying to figure out how much set saws need. A feeler gauge turned out to be the easy way to accurately measure the width of a kerf. For that purpose, the stated thicknesses of the gauge blades didn't matter either, in fact most of the shim markings on my set are now illegible, so I simply tried combinations of blades 'til they neatly fitted the kerf & mic'd them - more direct than adding-up a bunch of separate numbers anyway.....

    Cheers,
    IW

  12. #26
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    Luke, a few comments from my experience:

    1. The lapping surface must stay flat. Best to use glass or granite on a supported flat surface, such as a jointer bed or bench.

    2. The longer the surface, the easier to lap the backs of chisels and planes. Long strokes use less energy in removing metal than several short strokes. My lapping board is a 1m long granite slab that is 10mm thick and 150mm wide.

    3. The most durable sandpaper is Zirconia. This is a blue sanding belt. Cut it open and spray contact glue to the glass/granite.

    4. Don't try and take short cuts - move to a coarser sandpaper if you are finding removing metal to be slow. Start around 80-100 grit if you need. Only very small blades should be done on diamond plates. Even a 250 grit diamond plate is not efficient compared with good Zirconia 120 grit.

    Regards from Perth

    Derek
    Visit www.inthewoodshop.com for tutorials on constructing handtools, handtool reviews, and my trials and tribulations with furniture builds.

  13. #27
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    I followed this thread and finally put my plan to action after many years procrastination,the no4 and no5 appeared flat but shavings still weren't ideal, something was wrong. So I went to the local granite dealer and he explained that he had no offcuts , he would cut a piece , 800x120 polished black, it would be flat and I ordered the zirconia belt 120g on line .picked up the granite , it was $30, checked it out on my bench, duuuoh,top was dished , checked with several means but found my well used and abused 1200 box section spirit level was straightest, light would shine through, and thin cardboard and paper revealed .3mm dishing through 80% of the length.took it back, don't think ill have much luck there, did my dough.turns out they do no grinding or sanding there only cutting.remembered I had an offcut of corian benchtop from 18 yrs ago when I built my home, , cut a section, 750 was the longest I could get, but it measured up flat to my best observation, contact sprayed up the zirconia, thanks Derek, and lapped my no4, brushing off the swage or whatever its called, it was obvious it was all over the place, flatness that is but say 15 minutes work and it was fixed, refined it on a diamond stone , also did the contact face of the chipbreaker as in the lengthy forum discussion, quick hone of the blade , man the plane produced super fine shavings ala Rob Crossman, even on gnarly river red gum that I thought was beyond planning, the no5 was worse, Turner body, stanley frog and group buy blade , it now produces as good or better, so thanks guys and especially Derek who nailed it in his last post, realise I'm just repeating old info but it makes a huge difference to my woodworking, Rossco

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