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  • belt grinder nearly finished

    I am getting close to getting my little belt grinder done.
    I don't have a vfd on it yet but I will soon.
    It is 3hp and runs very good.

    I made the drive wheel myself. It is 180mm diameter and 52mm wide out of steel. I only made it out of steel because I had the steel. I will probably get a rubber contact wheel for the drive wheel.

    Location: The Black Forest in Germany

    How to become a millionaire: Start out with 10 million and take up machining as a hobby!

  • #2
    My reply disappeared?

    But what I said was: Nice JoB! and how fast does that spin your
    belts? (SFPM?)

    Comment


    • #3
      Looking good.

      The main verticle upright, how thick is that , it appears to be about 1/2 inch plate?

      Any vibration problems?

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      • #4
        Forgot to ask,, the green machine in the back with the control knobs, what is that?

        Thanks.

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        • #5
          Black Forest,you may find that the back plate(platen) needs to be the same width as the belt,or it will not let you grind something like a step, which needs to be ground using the very edge of the belt.

          You will also find that the bracket,which you have welded to the SIDE of the platen,will get in your way when you need to grind a step on that side of the belt. It is a PITA,but I suggest that you contrive to make bends in the support piece I refer to,and weld it to the BACK of your platen. That way,you have full access to grind on either edge of the belt.

          If you will look back at the pictures of my Bowie knife,look at the way the grinds are terminated. The edges of the belt were needed to terminate the grind(though,in that case,the edges of the contact wheel were used).

          The platen will soon get worn. I made a fully hardened plate of A2 steel,with 4 holes in it. One in each corner,countersunk on BOTH sides. This is bolted to the soft platen,and can be turned over when it gets worn. Another can be made when both sides get worn. The fully hardened A2 is pretty slow to get worn. On my Wilton Square Wheel grinder,the cast iron platen got worn fairly soon,and years ago,a new one was $100.00. Cast iron will last longer than your mild steel one,too. I just made the A2 wear plates instead of buying new platens periodically. I was able to machine the cast iron platen once or twice,to get it flat again,but it soon got too thin. Wear plates are better.

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          • #6
            THe plate is 10mm thick. Do you think it is too thin?

            The green machine is my band saw.

            I calculated I am getting 5200 SFM. I have a 80 grit belt on there now.
            Location: The Black Forest in Germany

            How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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            • #7
              I changed the platen as suggested. Nothing fancy but it is much better.
              Location: The Black Forest in Germany

              How to become a millionaire: Start out with 10 million and take up machining as a hobby!

              Comment


              • #8
                5200 sounds a little fast. You're grinding metal with it right?
                I think mine is 3000 and it still feels fast. I have no speed control.

                Comment


                • #9
                  Not to hijack your thread.. but here's a quick question for everyone
                  thats following.. and maybe might lead to improvements in yours..

                  but on mine, no matter how taut I make my belt, if I take anything more
                  than light passes (light pressure) I tend to round my leading edge. Hope
                  this drawing makes sense:



                  the red line is my belt.
                  the purple line is what I *think* is happening.. its quite exaggerated
                  in the drawing.. in reality it looks flat as always.

                  My platen is positioned maybe 1/16" forward of the belt plane.

                  I've always wondered if it wasn't a function of my platen?
                  Maybe it should have some UHMW on it? Its just a piece of flycut
                  CRS.. perhaps too much friction?

                  Or my tensioning system just can't get things tight enough?

                  Or I'm expecting too much from a belt grinder.

                  Comment


                  • #10
                    Yes,there is always that annoying slight rounding no matter how tight you get the belt,at least when grinding with the flat platen. No such problem when grinding against the wheel,though.

                    I may have mentioned,when I wanted to make the Bowie knife I posted,I wanted to simulate the old knives,which were ground on very large diameter grinding wheels. I ground a block of steel with a slight radius on its face,and welded an arm on it to screw it against the flat platen from behind. It works great. The belt just runs around the curve on the steel block,leaving a much less hollow grind on a blade.

                    The block of steel is about 3/4" thick,partly bandsawed to a curve,then belt ground to a finished curve.

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                    • #11
                      I made two knobs to go on the bolts that hold the table and platen in place.

                      The back two bolts don't need a knob or nut. They are just there to position the two in the right place.

                      This was my first try at making anything like this so be gentle!
                      Location: The Black Forest in Germany

                      How to become a millionaire: Start out with 10 million and take up machining as a hobby!

                      Comment


                      • #12
                        Originally posted by sasquatch
                        Forgot to ask,, the green machine in the back with the control knobs, what is that?

                        Thanks.
                        I think that might be his $5,000 coffee maker.

                        Brian
                        OPEN EYES, OPEN EARS, OPEN MIND

                        THINK HARDER

                        BETTER TO HAVE TOOLS YOU DON'T NEED THAN TO NEED TOOLS YOU DON'T HAVE

                        MY NAME IS BRIAN AND I AM A TOOLOHOLIC

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                        • #13
                          Does the rounding effect still happen if the pully on the top has more friction than the pulley on the bottom?

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                          • #14
                            Very nice job Black Forest !

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                            • #15
                              The rounding effect on a machine like the Wilton Square Wheel grinder,where you can get the belt pretty tight,is minimal,but still there. You can only get the belts so tight,or their seams will tear loose. Those belts are violent when they go BLAM!!!! Their edges can cut the daylights out of you,too. Very messy,abraded cuts. I prefer the Wilton because it encloses the belt,except where it has to be exposed. Haven't been cut by a belt yet,but have had some blow up on me.

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