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Darex Conundrum

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  • Darex Conundrum

    I picked this sharpener up a while back at an estate sale. It is an M1, but the chucks that I got with it are from an M2. The guide profile must be different. They cut a huge center chisel in the bit, with no way to adjust that part of the cut. Original chucks for the M1 seem unobtainable. Would it be worth holding out for a possible not clapped out M2 body without chucks? Was the M2 any good? I have seen a couple M2's with no chucks come up on eBay, but they look clapped out, missing other parts in addition to no chucks, and at over $300 shipped, that hardly seems worth it for what is basically a 40 year old used grinder. Opinions? Dump the Darex parts and opt for something else?





  • #2
    Looks like an indexing issue. How are the drills indexed in the chuck?
    Southwest Utah

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    • #3
      Originally posted by chipmaker4130 View Post
      Looks like an indexing issue. How are the drills indexed in the chuck?
      Outer wheel on chuck for depth, inner for relief. Changing the relief does not fix the center being too wide. The contour of the wings and the lip in front of that act as compound guides, and are non adjustable. I think I would have to somehow change the contact relations of the posts to correct it.


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      • #4
        If by "width" you mean how long the chisel point is, that may have nothing whatsoever to do with the grinder. It has mostly to do with the thickness of the "web", the center of the drill, which increases as the drill is ground back. You need to do "point thinning" to reduce it.

        There is a portion of that which has to do with the chisel point in relation to the narrowest point on the "web". If the line of the chisel were more directly across the web, it would be shorter. But the geometry of the point usually sets the chisel in relation to the web.

        http://www.mitsubishicarbide.com/en/...ng_terminology
        CNC machines only go through the motions

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        • #5
          Good Post Jerry
          That Link should be in everyone's "favorite tab"
          Rich
          Green Bay, WI

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          • #6
            Originally posted by J Tiers View Post
            If by "width" you mean how long the chisel point is, that may have nothing whatsoever to do with the grinder. It has mostly to do with the thickness of the "web", the center of the drill, which increases as the drill is ground back. You need to do "point thinning" to reduce it.

            There is a portion of that which has to do with the chisel point in relation to the narrowest point on the "web". If the line of the chisel were more directly across the web, it would be shorter. But the geometry of the point usually sets the chisel in relation to the web.

            http://www.mitsubishicarbide.com/en/...ng_terminology

            Thanks for posting that, very informative. But if I take a factory sharpened bit with no point thinning,



            And then sharpen that same bit per instructions



            On the close up you can see it is not just a wider chisel point, on the same bit that had a smaller one with no thinning, but a rounded mess, and a beyond inefficient cutting profile. This is what is making me think the chucks may not be cross compatible between the M1 and M2.

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            • #7
              It is not indexed correctly or it may also be set for excessive clearance. Are those things adjustable with this machine?

              Edit: I see a "less" and "more" clearance adjustment. Kick it all the way to "less" and see what that looks like.
              Last edited by eKretz; 03-24-2021, 01:05 AM.

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              • #8
                Maybe I am doing something wrong. Would not be the first time. I will try changing the orientation of the bit around.

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                • #9
                  Generally, you can look at the angle of the line formed where the grinds meet at the web and get a good idea if the drill is indexed correctly or is ground with too much clearance. That line should generally be about 115°-120° to the cutting edge lip when there's a standard ~10° clearance and the drill is indexed correctly. What I see on your drill is more like a 135° angle. That would be relatively high clearance if the drill is indexed correctly, so I'm leaning toward an indexing error - whether that's you or that someone has something set wrong on the machine I can't say. Do you have the manual?

                  How do you set the "stickout" of the drill? That is a critical dimension also in order to get the indexing correct.
                  Last edited by eKretz; 03-24-2021, 04:19 AM.

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                  • #10
                    Contact Darex and request a user manual. Also ask if M2 chucks are compatible with a M1 machine.

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                    • #11
                      The web on a drill bit grows thicker as you move towards the shank. How worn are the bits you are resharpening? If "new" length was 3.50", have these been sharpened so many times that they are now only 2.00" long?
                      I also suggest contacting Darex, the M! may not be supported by parts, but technical service might still be available.

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                      • #12
                        Originally posted by junkaddict View Post
                        . . . I will try changing the orientation of the bit around.
                        That's what I meant by 'indexing'. Hard for me to tell from your photos and description exactly how its being done. Be sure to let us know if you get it to work.
                        Southwest Utah

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                        • #13
                          The chucks should be the same for both, the M1 was the stripped down version and the M2 had the whole thing built into the grinder. They both work the same way.
                          The shortest distance between two points is a circle of infinite diameter.

                          Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

                          Southwestern Ontario. Canada

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                          • #14
                            stickout? i thought the drill just gets rotated on a cam. does it matter?

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                            • #15
                              Yes it does matter. Changing the amount the drill sticks out will change the angular relationship between the cams and the cutting lips because of the way the drill rotation is indexed.

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