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Thread: Heat damage to blades when grinding...

  1. #91
    Quote Originally Posted by Reinis Kanders View Post
    Thanks. I found the website, just was not sure about it.
    By the way, I noticed the website was a bit plainer. I contacted the guy through ebay on a best offer auction for a damaged wheel (that had shipping damage around the back side of the radius that a turner might care about, but we wouldn't), and then found his site after looking up the logo on the wheel because someone else bought the damaged wheel before he got to the offer I submitted. I figured if I wasn't buying the wheel listed on ebay, I didn't need to give them 10% of his money, they made their cut on the wheel I missed out on.

    From the time I located his website to the time I had a radius wheel (like the ones being discussed) at my doorstep was two days. Since I have a grinder with a 1/2 inch arbor, I figured I'd rather buy a wheel milled to that than have to buy a separate bushing. The only thing I'd choose different on a second purchase is a 180 grit wheel instead of 80, but the grind is not so harsh by any means that you can't use the 80 grit wheel, it's just not necessary to have it that coarse when we do mostly light grinding.

    Long story short, the website is legitimate and so is the guy. (I have no affiliation with him and he didn't give me a discount to mention him or anything).

  2. #92
    Thanks for the info Dave and Mike. I am now trying to decide on whether I should I go with and 8 or 6 inch wheels.
    After some thought it seems that 8 inch wheels do not really have any real advantages since CBN wheel diameter does not change with wear.

  3. #93
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    Quote Originally Posted by Reinis Kanders View Post
    Thanks for the info Dave and Mike. I am now trying to decide on whether I should I go with and 8 or 6 inch wheels.
    After some thought it seems that 8 inch wheels do not really have any real advantages since CBN wheel diameter does not change with wear.
    Reinis

    8" will create a shallower hollow. Put another way, the 6" wheel may create a deeper hollow that you might want.

    Regards from Perth

    Derek

  4. #94
    An 8" will also remove material faster than a 6" if spun at the same rpm.
    -Dan

  5. #95
    Decided to go with 8 inch from Wood Turners Wonders, but now they are out of stock so I have to wait.
    After I pulled it out of storage my grinder actually turned out to be 8 inch one which made my decision an easy one.

    I was also looking at Sorby's belt sander setup because two CBN wheels and new grinder end up costing almost the same.
    Last edited by Reinis Kanders; 10-28-2014 at 5:28 PM.

  6. #96
    I think you'll be happier with the grinder and wheels than the belt sharpener. No consumables, either. Two of those wheels in 8 inch size will have a ton of rotational energy.

  7. #97
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    Thinking aloud to share some more on possible options for flat grinding bevels for anybody that may have an interest. Think there's several more or less DIY options that may be runners since there's not a lot ready made coming up. Thinking as well that bench grinder based solutions have a lot of potential - if fitted with CBN or low heat wheels, and possibly if run at low speed. (this latter might compromise metal removal capability more than is ideal for heavy jobs/but high speed may be OK too with low heat wheels)

    1. Use a bench grinder, but fit one end with a cup or recessed centre wheel of appropriate type - and grind by moving the bevel (and dressing tool as needed) acros the side face of the wheel. CBN would be really nice, but may not be available in this format. (?) Hopefully something like Norton 3X is. This video is about building a fixture to hold lathe tools for grinding this way, there's pictures of the final rig around 7.00 onwards. It could be done more simply - not much more costly than a hollow grinding set up - but it illustrates the principle/layout: http://www.youtube.com/watch?v=JdoVWoUMBVs

    One advantage is that the grinder would be available for other work, and would permit hollow bevel grinding if this was required also. Presume a 6in machine would be Ok, probably also high speed.

    2. Adapt a belt sander with a properly set up platform from which to mount jigs and/or use a honing guide to set bevel angles. Getting quite a bit more expensive (belt systems inevitably have more parts and complexity), but perhaps advantages too if a Multitool bench grinder mounted item is used: http://www.trick-tools.com/Multitool...1#.VFAxq94kMlw A normal high speed single phase induction motor might be a better option than a bench grinder, in that it would permit VFD control of speed if required.

    3. Adapt the currently used disc sander to mount a 10in dia diamond lapidary disc using self adhesive magnetic sheet (cooler and longer lasting and more easily changed than self adhesive abrasive discs - turns out that 10in discs are available from China on EBay), and add a VFD for speed control for lighter work.

    Just flying kites while waiting for inspiration/insight to dawn. Hollow bevel grinding on a bench grinder is pretty clearly the simplest and most cost effective option.
    Last edited by ian maybury; 10-29-2014 at 5:17 AM.

  8. #98
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    8" grinders usually run slower than 6" grinders so their wheels don't fly apart.

  9. #99
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    Just flying kites while waiting for inspiration/insight to dawn. Hollow bevel grinding on a bench grinder is pretty clearly the simplest and most cost effective option.[/QUOTE]
    Hello Ian. As you have redone the 50 degree bevels of the Veritas irons, and do have the option of buying either 25 or 38 degree irons for your bevel up planes, I'm wondering if just the Shapton 120 with a jig or freehand might be sufficient to give you a flat bevel and remove small edge chips, allowing you also to remove microbevels if you choose? You're (we're) sharpening for only yourself and not a woodworking school.
    I've valued the advice on this forum, especially David's. I can see myself successfully grinding a 1/2" chisel but not a 2 3/8" iron. To have any chance at the latter without gouges and serrations I would need an additional sliding guide attached to the tool rest. Reading reviews of the sub $100 grinders, I envision wobbly wheels from bent shafts or distorted fittings. I have bought too many mediocre goods to readily go that route again. These are just my thoughts, not meant to counter the observations of those adept at grinding.

  10. Quote Originally Posted by Bruce Mack View Post
    Just flying kites while waiting for inspiration/insight to dawn. Hollow bevel grinding on a bench grinder is pretty clearly the simplest and most cost effective option.

    Hello Ian. As you have redone the 50 degree bevels of the Veritas irons, and do have the option of buying either 25 or 38 degree irons for your bevel up planes, I'm wondering if just the Shapton 120 with a jig or freehand might be sufficient to give you a flat bevel and remove small edge chips, allowing you also to remove microbevels if you choose? You're (we're) sharpening for only yourself and not a woodworking school.
    I've valued the advice on this forum, especially David's. I can see myself successfully grinding a 1/2" chisel but not a 2 3/8" iron. To have any chance at the latter without gouges and serrations I would need an additional sliding guide attached to the tool rest. Reading reviews of the sub $100 grinders, I envision wobbly wheels from bent shafts or distorted fittings. I have bought too many mediocre goods to readily go that route again. These are just my thoughts, not meant to counter the observations of those adept at grinding.[/QUOTE]


    The skill to grind a decent bevel isn't too hard to acquire. It does take some practice, but don't assume that you need jigs.

  11. #101
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    Ta George, add Bruce and Bridger's observations and it's pretty clear that a cheapest of the cheap bench grinder would not be a good choice. Need to buy a bench grinder anyway, as i've been getting by with a unit self built on a saw spindle about 35 years ago. We don't get the same choice here as in the US though - tends to jump from junk to expensive.

    Guess I'm past the worst on the re-angling of plane irons Bruce, and the WorkSharp will certainly re-work bevels/grind off honing bevels. Against that, and given the way this stuff tends to shake out it'd seem a pity when going for a grinding solution not to get/build something with the full range of capability as sure as eggs some unforeseen need will come up.

    On guides when grinding. Lots manage it freehand using a finger against the tool rest to guide the tool. Veritas and others do a grinding rest with a built in guide rail: http://www.leevalley.com/US/wood/pag...=1,43072,45938

    I'm starting to sound like a commercial for hollow grinding and using a micro as opposed to single bevel - in that what's acceptable when bevel grinding depends a lot on what of sharpening method you are using. The hollow grind/micro bevel route has got to be a lot more tolerant of minor grinding inaccuracies. Single flat bevel sharpening in comparison on e.g. Japanese chisels requires a really flat and accurately angled grind if lots of remedial work when honing on the waterstones is to be avoided - especially if using a honing guide. The Veritas Mk 2 honing guide (but it needed some dialling in to sort out a roller misalignment) makes a good job of this on the top of the WorkSharp. I'm hoping a you have said that the 120 Shapton will prove fast enough for doing it too - it'd be much simpler and less prone to errors.

    Flat bevel grinding/re-grinding of BU plane blades is also less critical/tolerant of minor misalignments if micro bevels are being used - it's the single bevel that ups the ante.

    The insight that pops out of this sort of discussion is that even seemingly simple sharpening techniques depend on a whole series of stacked assumptions to work....

  12. #102
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    A couple questions about setting up these CBN wheels. I picked up a Delta 8" variable speed grinder the other day at Lowe's to try it out with the CBN wheel. I have not turned the new machine on with the new wheel yet as a couple things worry me a little. I still have the box and can return it.

    Wheel guards
    Most of the pictures I have seen of mounted CBN wheels are of grinders without any sort of guard. Either they are removed so that viewers can see better or they just are not needed or both. I have read, at least in the case of the 80 grit wheels, that sizable particles are removed. I imagine one can protect eyes, face and hands with a welders mask. I have the 180 grit wheel but I am considering the 80 too. It would seem like the clear plastic, see through guards might help, but on the Delta these guides attach to the inside wheel guard. On the Delta the outside guard has to be removed to mount a 1 1/2" wheel, but the inside guard can be left on, retaining the clear guards. I suspect the major reason for the wheel guard on grinders is the rare case of a stone wheel coming apart at high speed. I don't think the heavy metal CBN wheels are apt to come apart, even in the highly unlikely case of a crack so I suspect the main reason for these guards is a mute point on a grinder running CBN wheels? Were I to decide to use the Delta grinder without any guards on the side with the CBN I am not sure if it would be a problem to leave the guards on the remaining stone wheel. Dave mentions in his video that he does not feel it is a problem to run a solo CBN wheel on a standard 2 wheel grinder. If this is the case then I doubt leaving all the guards in place on one side of the machine will cause balance or vibration issues on the CBN wheel side. It does seem logical to me though that having two different shaped, different weight...objects on opposing sides of a spinning arbor must have some consequences. Ultimately I think having two CBN wheels of the same size and weight would be optimal but, I am not sure what differences not having equal spinning object might entail?

    Arbor space
    The 1 1/2" wheel I have fits on the 5/8" arbor fine (with the 5/8" bushing) but the bolt does not quite have enough room to get entirely through the nut. I don't think this is a big problem as the nut is engaging all but maybe one or two threads, still probably not optimum? On the D-Way web site Dave has a video on installing his wheels. In the video he says his wheels require 2 1/8" of usable arbor space, but he also has a message that comes on the screen saying that Dave meant to say 2" minimum. The Delta grinder has just a hair over 2" according to my Starrett square.

    I am wondering if I should look into another type grinder with more arbor length on each side and a larger motor?
    Last edited by Mike Holbrook; 10-29-2014 at 10:44 AM.

  13. #103
    There are substantial particles coming from the 80 grit wheel, I can confirm that. You don't want them to end up in your eye. I've been in the ER before with metal in my eye, it's a nuisance for several days after you get it removed. At a minimum I would wear safety glasses grinding with one and no guard, and I generally don't use safety glasses with my grinder - I stand to the inside of the guard so that no particle can get in my eye without at least having to bounce off of another surface and lose a lot of momentum.

    (my eye issue was actually from metal particles coming off of a belt sander and not a dry grinder)

  14. #104
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    David, how high up the wheel are you grinding? Off the 180 grit I get just a little fine dust, which goes straight down. The guard is off my wheel. Is yours?

    Regards from Perth

    Derek

  15. #105
    My guard is on. I grind where the stock baldor rests go, which is probably halfway up the wheel or a little more. I do have part of my cast guards on (there is no way the wheel would fit inside them), which is the inside half and I can avoid flying particles by standing just to the left of the rest (or rather putting my head there).

    It's possible that the pieces that have hit me in the head have bounced off of something, most of what I feel us large particles hitting my fingers below the grind point.

    The 80 grit wheel takes off big particles. You'd be surprised how deep it cuts. The grind marks must be twice as deep as the pink 46 grit wheel.

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