Topics include, Machine Tools & Tooling, Precision Measuring, Materials and their Properties, Electrical discussions related to machine tools, setups, fixtures and jigs and other general discussion related to amateur machining.
best way to learn, practice, and dial in your edge finding. take a known item, such as a 1-2-3 block. clean, stone, and verify the actual dimensions. place in vice. and pick a direction. say over the 3 inch length. come up to an edge and find it. zero your read out, or your dials. keep practicing till you are repeating well. might even set a travel indicater from the vise to the spindle. watch the edge finder! pick up. then look at the indicater or the read out to see if you are repeating. and see how much backlash you have if you will be using the dials. now is the fun part. raise up and edge find the other side. if you are using a .2 finder for example the read out should read 3.200 if not then dial in the rpms till you get this dimension from side to side. start at 1,000 rpm's and work up till when you pick up on side then to the other and you get the exact length plus the diameter of the edge finder. generaly if the length is short, speed up the spindle. i always verify a new edge finder this way, and double check my pick ups this way if i am not using an indicater to pick up my work. when you get the hang of it, you can tram, pick up all four sides, and double check the part and pick up very quickly. if the dimensions don't come out right, the red flag is waving! i find that the standard starrets work best at 1500 rpm's.
Grant
If your table position reference is a dial, these edgefinders are fine for your work. If you are using .0002 or less digitals or rods and an indicator like on a jig bore, you may want to use another method of edge finding.
Grant,
If you want to measure a 3" block for example.
Your first contact will be in the positive motion
but the far edge will be contacted goind back and you ahve the backlash in your measure.
Is OK if you do the second contact going in the positive direction and read the dial when the finder goes from kicked out to aligned.
Then you should read 3.200".
Mauro,
thats why i commented about measuring your backlash, i forgot to comment about adding that into the second pickup. but double check that backlash at the second point as it may well me diferrent than the first place!
and the edge finders only work going into the workpiece, not comming out!
my posting was to help a person learn how to use one , and to double check ones results to know if they are .100 from edge or .098, .103! the rpm's will greatly change one #'s.
this process best works on a machine with readouts though, removes questions about the backlash.
Grant
