12 Replies Latest reply on Mar 11, 2015 11:35 AM by Chris Michalski

    work holding

    Sam Molony

      Hi all,

       

      I am aware this is not directly related to topics of this forum, however I would imagine there are many members who are experienced in manufacturing alongside their CAD.

       

      I am looking to machine the component shown in the below image, using the most efficient work holding method.

       

      I have thought to maybe use a vice for the central features and then bolt the part down to the bench using the holes to machine around the outer profile.

      or

      to grip the initial material in a vice, machine the central features and then machine around the outer profile leaving 1mm at the bottom as not to completely seperate the component, then peel it out later,

       

      Thanks all

        • Re: work holding
          jason van clark

          Start with a piece that is .75" thick.  Mill your piece complete leaving 'clamp material' on the back.  Then, flip it over and machine off the excess.  Done in one setup

            • Re: work holding
              Sam Molony

              Hi, thanks for the reply

               

              I had the same idea, the only thing I thought is that it will become loose as you start to machine the material away, which could cause a defect.

               

              Please let me know if I am misunderstanding you

               

              Thanks

              • Re: work holding
                Jamil Snead

                I would do something similar, except I would probably start with 5/8" thick material, as that would still give over 1/8" to hold onto in the vise for the first op. Then for the second op I would use soft jaws in a vise that were machined to conform to the part shape and clamp on the part almost all the way up. Then just face off the extra material that was held in the vise initially.

              • Re: work holding
                Deepak Gupta

                I would prefer to do it in one step like Jason suggested. And when you flip over to machine the back side, instead of vice, use clamps to hole the component. You may have to change the position of the clamps during machining.

                  • Re: work holding
                    Sam Molony

                    Hi Deepak,

                     

                    Thanks for the reply.

                     

                    I'm not sure I understand you when you refer to 'one step', surely if you have to flip the material over it is more than one?

                     

                    Although it would be in one step if the part was machined as I described in the second instance in the original question.

                      • Re: work holding
                        Deepak Gupta

                        Oh, by one step I meant that major work is finished in one setting. Sorry if I was not clear.

                         

                        And I don't think 1mm would be a great holding in a vice.

                          • Re: work holding
                            Sam Molony

                            The 1mm doesn't refer to the material which would be held in a vice,but the amount of material left at the bottom of the cut, the material can be as wide as is desired to allow for clamp material.

                             

                            The method which I think may be the best is to machine all central features, then bolt the part down using the countersunk holes, and machine the outer profile.  

                            This means that the part does not need to be moved/flipped

                             

                            Would you agree?

                             

                            Thanks for your replies Deepak

                      • Re: work holding
                        J. Mather

                        How many of these are you making?

                        One or a "bunch"?

                         

                        Actually I don't think it would matter to me.

                         

                        I would clamp to a base of aluminum.

                        Machine the 3 holes (adding tapped holes into the aluminum tooling plate if first or only part).

                        Bolt down, remove clamps and finish machine the rest of the features.

                         

                        One (trivial) simple (reusable) tooling plate with 3 holes.

                        No change in set-up between cuts. (flip over?  why would the part ever need to be flipped?  start with 3/4" stock? why?)

                         

                        Is the start a casting or stock plate?

                        • Re: work holding
                          Chris Michalski

                          I'm with JMather - if you're making more than one make a fixture plate with perimeter clamp holes and the 3 mounting holes.

                          Clamp a piece of 10mm and machine the 3 holes.  Install 3 bolts.  Machine the remaining features.  Done in one fixturing.

                           

                          The fixture plate will have a groove where you cut through the perimeter of the part but that doesn't matter.

                          And if the tolerances or surface finish are critical start thicker and face the plate as the first step.

                          Even for a one-off piece that's still likely easiest.  Unless you do it in one step or use a fixture plate the alignment of your holes isn't going to be precise when you re-clamp it to finish the perimeter (i.e. making sure they are along the true X-axis of the mill).