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Protractor Base for Grinder mounted on cross-slide

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  • #16
    I believe that the first thing that I would do is to try and tilt the motor and housing back, so that I would be able to see the point of contact better.
    John b. SW Chicago burbs.

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    • #17
      Some radical ideas:

      1) Make a "z-plate" to hold the grinder foot in front of the compound, and low enough to be on center. The pressure involved in grinding is not enough to cause deflections, and most grinder mounts from Dumore etc end up with the spindle center in front of the compound anyway.

      2) The spindle housing appears to attach to the motor support/belt housing by 4 symmetrical screws. Take it off, and turn it 90 degrees so that it is behind, and no longer under the spindle. Make a bracket to hold it on the compound level with the lathe spindle.

      3) Same idea, but turn it 180 degrees, so the "foot" is up. Make a bracket to hold it on the compound. That probably lets it be less far in front of the compound, but is a bit of a "kludge".

      4) very radical.....Get entirely rid of that "foot", which was a horrible design idea by somebody in china..... Saw it off, and take the grinder apart far enough to turn that housing cylindrical. Make a low profile clamp housing that will hold it on top of the compound.

      Ideas 1, 2, and 3 do not modify the thing in any permanent way, if it suffers any warranty issues. The last obviously does, but also offers the best chance of a good solid mounting without "kludges". Plus it allows the motor to be adjusted to an angle allowing better visibility.
      Last edited by J Tiers; 05-03-2021, 11:58 AM.
      2801 3147 6749 8779 4900 4900 4900

      Keep eye on ball.
      Hashim Khan


      It's just a box of rain, I don't know who put it there.

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      • #18
        Here we have a 3D model of my lathe with a 3D model of the new grinder from Little Machine Shop. There is about 1 1/4" vertical clearance between the underside of the grinder base and the top of my cross slide when the center of the lathe chuck is horizontal with the centerline of the grinder.

        Brian Rupnow
        Design engineer
        Barrie, Ontario, Canada

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        • #19
          It appears that I could make a new protractor topslide that would allow me to grind a taper with the toolpost grinder from Little Machine Shop. It wouldn't be easy, but it's doable. It would require making at least 3 new major pieces and cantilevering most of the grinder out towards the headstock side of the cross-slide, but it would allow me to grind at least 2 1/2" of taper. Remember, my DRO for my Y axis is attached to the headstock side of the cross-slide, and I have to get out far enough to clear it.


          Brian Rupnow
          Design engineer
          Barrie, Ontario, Canada

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          • #20
            These parts aren't terribly complex to machine. I've never machined a dovetail before. I could certainly buy a dovetail cutting tool and teach myself how to use it. I haven't included the gib strip , endplate, nor adjusting handle here, but they are all simple shapes. This is just a "what if" exercise for now. Right now if I use the new toolpost grinder in my compression ring making exercise, it can just bolt squarely to the grey cross-slide.
            Brian Rupnow
            Design engineer
            Barrie, Ontario, Canada

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            • #21
              Originally posted by brian Rupnow View Post
              Paul---The biggest drawback to mounting a grinder in place of the toolpost, is that the backing dimension from the mounting base of the grinder to the center of the grinder spindle is 2". The distance from the center of my lathe chuck to the top of the compound is only 7/8". As I understand things, the centerline of the grinder spindle must be on the centerline of the chuck spindle, horizontally. The vertical backing on my lathe is 3 3/8" down to the top of the topslide. It may be possible to design a much slimmer compound to fit in that 1 3/8" gap, but I haven't looked at it closely. I won't really do much design wise until I have the grinder here.-----Brian.
              How about an L plate off the compound so the grinder itself sits to the side of the compound? This would never work for a cutter. But when grinding the forces are very low. So hanging the grinder offset to the side of the compound is quite doable I would think. Make it so the L can be flipped to either side to allow for external or internal work within the range of travel needed.

              EDITED- I'm three or four posts behind already I see. JT is thinking the same way as me with his idea to hang the grinder off the end. Or to either side for that matter. And I see that you're already a few steps ahead of even that idea with the idea of making a whole new low profile base.
              Last edited by BCRider; 05-04-2021, 11:56 AM.
              Chilliwack BC, Canada

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              • #22
                Originally posted by BCRider View Post

                How about an L plate off the compound so the grinder itself sits to the side of the compound? This would never work for a cutter. But when grinding the forces are very low. So hanging the grinder offset to the side of the compound is quite doable I would think. Make it so the L can be flipped to either side to allow for external or internal work within the range of travel needed.
                Yes..... #1 of the "radical ideas" above. Actually, I suggested a "Z" plate, but it amounts to the same thing.

                I am not seeing the need for a new compound.

                The usual TPG does not have the spindle over the mounting point for just that reason.... getting the spindle on center height. Here is a view of the Dumore showing that it is in front of the post mount.

                In the pic it is mounted on my "T&C grinder" base, but it has been on the lathe and likely will be again.

                2801 3147 6749 8779 4900 4900 4900

                Keep eye on ball.
                Hashim Khan


                It's just a box of rain, I don't know who put it there.

                Comment


                • #23
                  Yep, I noticed your Z idea and mentioned it in my edit above. And looking at Brian's drawing it appears that it would not easily mount to a side face. So the "Z" shape might be more suitable. It would depend on if the motor arm and belt cover can be rotated so they can stand up if the mounting foot is sitting on a vertical surface.
                  Chilliwack BC, Canada

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                  • #24
                    Now that I have designed a way in which the Little Machine Shop Toolpost Grinder can be mounted to my lathe so that that it can be used to turn tapers, it's time to get back to reality. The reality is that I don't really need this ability to turn tapers right now, even if it is a nice design exercise. I only need the toolpost grinder to travel in the X or Y axis. To do this I only need one adapter plate, and the nice thing is that I don't even have to remove my topslide or quick change toolpost to do it. The adapter is made from 1 1/4" thick aluminum plate which picks up the bolt pattern of the grinder and the two keyed slots in my current cross-slide.
                    Brian Rupnow
                    Design engineer
                    Barrie, Ontario, Canada

                    Comment


                    • #25
                      Originally posted by BCRider View Post
                      Yep, I noticed your Z idea and mentioned it in my edit above. And looking at Brian's drawing it appears that it would not easily mount to a side face. So the "Z" shape might be more suitable. It would depend on if the motor arm and belt cover can be rotated so they can stand up if the mounting foot is sitting on a vertical surface.
                      Actually that was a different suggestion, the Z would sit on top, reach over the edge, and provide a flat surface to bolt it to as-is. There were some wilder ideas, including a 90 deg turn of the "foot"

                      Brian seems to have decided not to bother, and can get to work now. If he ever decides to go back to the angled feed, maybe he will want some of our wild ideas.......
                      2801 3147 6749 8779 4900 4900 4900

                      Keep eye on ball.
                      Hashim Khan


                      It's just a box of rain, I don't know who put it there.

                      Comment


                      • #26
                        Jerry---I do listen. I read every post. Sometimes I even see a better idea than the one I had originally. Don't get your knickers in a knot about the fact that I didn't use your idea----this time. I ask questions on this forum because there are people on here brighter or with more experience than me. Keep in mind, I've only been machining for about 12 years now. There are people on this forum who have been machining for 50 years.
                        Brian Rupnow
                        Design engineer
                        Barrie, Ontario, Canada

                        Comment


                        • #27
                          Originally posted by brian Rupnow View Post
                          Jerry---I do listen. I read every post. Sometimes I even see a better idea than the one I had originally. Don't get your knickers in a knot about the fact that I didn't use your idea----this time. I ask questions on this forum because there are people on here brighter or with more experience than me. Keep in mind, I've only been machining for about 12 years now. There are people on this forum who have been machining for 50 years.
                          My knickers are fine... I was "talking to "BCR" about the stuff we came up with. You know what you want, and as a "designer", I totally "get it". I said "wild ideas", and that's what I meant..... some of mine are off-the wall, and that's good. If some of the ideas are not crazy, then you have not been creative enough yet.
                          2801 3147 6749 8779 4900 4900 4900

                          Keep eye on ball.
                          Hashim Khan


                          It's just a box of rain, I don't know who put it there.

                          Comment


                          • #28
                            A good days work, well done!! The toolpost grinder is attached to an approximate 1 3/16" thick aluminum plate. The aluminum plate has four bolts that go through zero clearance holes in the plate and through the topslide to two long custom crafted tee nuts. I am very fortunate to have tee slots in my cross slide. That piece of round bar in the lathe chuck is 1 1/4" diameter. ---The nice part of all this is that I don't even have to remove my topslide and quick change toolpost!!!


                            Brian Rupnow
                            Design engineer
                            Barrie, Ontario, Canada

                            Comment


                            • #29
                              Yeah, nice crosslide!!!!

                              One thing that old iron does not usually have..... is t-slots located there. Mine doesn't anyhow. Fairly simple way to get the grinder there, and nice that the toolpost does not need removed!!
                              2801 3147 6749 8779 4900 4900 4900

                              Keep eye on ball.
                              Hashim Khan


                              It's just a box of rain, I don't know who put it there.

                              Comment

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