Co-Axial Indicators

[DLM]

Does any one use or have a Co-Axial Ind. . Are they worth the cost & save that much time in set ups. What do most of you use to center work in a mill.

I have been using a dial ind. and it has worked good but it is sticking and not moving freely so i need to replace it . And was wondering about a co-axial ind. Thanks Don in Pueblo Co.

 

[Sparticusrye]

I use an edge finder for locating parts in a mill. They're easy to use and cheap. Fairly accurate. If I need to be more accurate I put some masking tape on the edge of the part and then move the end mill up until the tape gets cut. Most masking tape is approx. 2mil in thickness. Easy to do.

http://www.busybeetools.com/products/EDGE-AND-CENTRE-FINDER-1%7B47%7D2IN.-DIA.html

James

 

[Swede]

I have two of them, and they do indeed work very well. After using one a couple of times, you'll find the setup and execution is quick, and you can center round stock or a bore to well below 0.000,5" or better.

About the only drawback is they do consume a bit of "Z" on the mill, and sometimes cannot be used because of this. But I love mine and use it all the time.

For less exacting work (but still accurate) the use of an edge finder works great, especially on a DRO-equipped mill. Guy Lautard called it the "Osbourne Maneuver" in his bedside reader series.

Essentially, you measure the circle, locate the edge finder as close to the 3-9 or 6-12 line as you can by eye, touch it off, then move to the center of the circle, remembering to account for 1/2 of the edge finder diameter. You then swap axis, do it again. Do this about 3 or 5 times, and it self-corrects to within the tolerances of the edge finder and your mill table or DRO.

 

[pete]

Don,
I own one and to be truthful the answer depends on a few things. What are your accuracy requirements, Size and type of mill? They do take up a fair ammount of vertical distance while using them. I use mine on a 3/4 sized Bridgeport clone knee mill. The ability to swing them at (my recommendation) slower rpm is great and yeah for me they do speed up the job and make it a lot easier. For dead on accuracy when trying to center something like a rotary table then there's a few steps you need to do one time only before using a Co-ax. If your trying to zero the R/Ts center of rotation to the mills spindle on the R/Ts center hole or the outer rim of the table you need to check each of those surfaces with a accurate Dial test indicator. All of the cheaper R/Ts have a slight runout on those surfaces so you need to record just how much and center punch a mark on the table at either the high or low point of the runout and allow for that runout while using the Co-axe. Doing it that way will get you as close to perfect as possible. If your R/T has degree markings on the table like most or all of them, Then I just record what degree mark is the high or low runout point. Before Using them under powered rotation you need to be fairly close to center to start with so your not trying to over travel the Co-axes limits, You just swing the spindle by hand a partial rotation and adjust your table travels till you get fairly close. But you'd need to do that with a D.I. or D.T.I. too.

A Co-axe isn't designed, Nor will it give you accurate measurements when trying to offset a part a measured ammount. The whole point of them is your trying for zero deflection on the needle as it swings around the part or something like that R/T.

They also work really well for quickly re centering a lathes tailstock if you've offset it for taper turning a part.

I have a Blake Co-axe and I can only repeat what I've read about the cheaper Chinese copys. Some people have had good luck with them and others found they were really inaccurate. So I guess it's a bit of a gamble for what you'd get buying one of those.

Pete