Which edge finder?

I bought one of the Vertex LED/ beep electronic types with the sprung loaded ball. It gets used at least twice a year. I must admit that I have never tested it's concentricity as Oily rag has mentioned. The glut of Chinese ones are currently on the market at 1/4 of the cost of my Taiwanese one. As the shank is 20mm, they will not be suitable for smaller machines.

I currently use a wobbler type which I find sufficient for my needs. I like the versatility of the Haimer but it price would be better invested in other tooling, that said I found this 3D sensor similar in function to the haimer but at 30% less in price **LINK**

ChrisB

Interesting link but I'd be chary about buying from a company that admits to selling their economy range without a test certificate. These devices are quite complex and their manner or working demands precision manufacture and set-up of the innards.

Given that the objective is to locate the centre of rotation of the spindle accurately in relation to the edge I instinctively feel that a simple rotation system with a reliable indication is a better approach than any static or complex calibrated system.

Static systems are vulnerable to unquantified directional errors in the spindle, holder or unit itself.

Calibrated systems need to be of high quality (=expensive) to work well and our sort of used doesn't really exploit the extra capability. One reason I've not used my Hamier is that I don't need the clever capabilities. But many folk, especially in the CNC world do.

All a wiggler really needs is a consistent offset to kick over. Doesn't matter is its 10 or 20 thou out so long as its always the same. Just correct the half probe diameter subtraction as needed to take out the error. Unfortunately the cheap oines tend to have some variation in performance.

Clive

I hope this is not to far of topic...

I have one of these edge finders -

It has always worked very well, very repeatable and easily set for zero run out. It has a small really oddball battery that fits inside its shaft. However..it no longer works - It relies on electrical contact between shaft and ball tip ( through the machine itself) and then the LED comes on - but the led no longer comes on..

I HAVE checked the battery, tried a new one, looked down the shaft battery hole with slim video camera, cleaned battery contacts, etc...Something has come adrift inside, or the LED has failed...Does anyone know how to open one of the things? I have tried unscrewing the body - there does not seem to be any unscrew witness marks, etc. The 4 grubscrews are to set the ball tip run out only. I did peal off the label strip - no screws hidden under..

I have emailed the company ( Japan) about 10 days ago, but...

Joe

I have a wiggler but found I could induce unacceptable variations. Moved to the Starrett type split cylinders which are much more consistent. A development of these which I use almost always is according to the packing "Z-Type". Simply a small diameter Starrett with a larger flange on each part at the intersection. I have found this design to be much more consistent and its signalling quicker for my ineptitude than the other types.

Regards

IanB

The wiggler type can be prone to 2 problems. One, the spring load on the ball and socket may not be ebough so it may have to be run very slow, which means that the approach has to be very slow too and you can easily overshoot. Two, if the chuck or the work is at all magnetic, it gets very erratic and the tip can jump on to the work and run off before it actually properly touches.

John

I'm surprised that a wiggler can be made with too little friction. Would have thought that to little would make it impossible to true up before starting. I "milk" mine very close to true first, auto-truing by banging off the workpiece on approach is inelegant bodgery.

Certainly all the issues I've seen are due to too much drag on inexpensive ones.

I find the key is to run around 150 - 200 rpm and watch for it to start to crawl sideways.

If you can get at both sides the 1/2 function on a DRO makes high accuracy much easier. I suspect most folk don't fully exploit it.

Magnetic workpieces are an issue with any uncalibrated revolving probe system using a steel probe. Back to dowel, and fag paper or 1 thou feeler stock. On both sides followed by the 1/2 function on the DRO in my case.

Clive

A lot of people don't cotton on to the fact that the DRO 1/2 function is also an excellent method for centering round work under the spindle with an edge finder as well as flat sided parts.

I resisted getting a DRO for a long time thinking it was just a gimmick, but once you have one it makes a milling machine so much quicker to set up and use.
Instead of fiddling round for ages trying to locate the work accurately by other antiquated methods, you can have the job set up and finished in a lot less time.

Phil

Well, at least one of the ones I bought had too little and isn't adjustable. Magnetism doesn't have nearly so much effect with the split cylinder type. Anyway my favourite approach is an electronic type. The one I have made is very robust to be (fairly) resistant to slight overtravel and the method of manufacture ensures good concentricity. Made originally for auto-zeroing the CNC mill but useful on the manual mill too using a "beeper".

I posted on Joe's CNC lathe thread a few details of the system I have on my lathe for tool calibration and stock end finding. This could be fitted to a mill too to sense contact for both height and edge setting without needing a specific probe. Not as precise as a Renishaw but much cheaper and more robust and doesn't eat daylight under the spindle.

Thanks for all the replies - more than I'd expected and I now have a few less unknown unknowns . In particular, I hadn't heard of the Huffam type so will look for a good used one to buy. In the meanwhile I'll stick with using the split cylinder type (and occasional paper and pin).

Dave, something to try if you purchase a split cylinder type and have a DRO. I go up to the edge being looked for and when it starts to "go" I zero the DRO, back off and try again a couple of times keeping an eye on the DRO as it counts down until I get a consistent zero adjusting the DRO as necessary. On the second side I do similar making a mental note of the DRO reading as I do a couple of count down checks.

Having received an electronic edge finder this week I searched for any comments on their efficacy & usage hence this post. It seems that there are varying views, &, as others, I have a wiggler set & the disc set which both have seen plenty of use but I am one of those 'nice to have ' guys so went & searched on Ali express & found this one. All the others I have seen have a 20mm shank which is too large for my ER25 collet or drill chuck but this has a 16mm shank which suits fine.

On initial trial it's very sensitive, lights up & gives a 'beep' on contact, which does require a very slow 'creep' to the edge of the object. the ball at the end is 10mm, & is spring loaded should you 'push too far', so you do have a ref. for setting your spindle on edge if you have DRO's . very economical price too compared to some prices.Usual disclaimer applies.

George.

I bought a Vertex electronic one years ago, the drawback with it is the 20mm body diameter, ok with R8 collets but a bit big for some machines. There are plenty of cheaper copies on the market at the moment. It has been used at least half a dozen times. I really got comfused when I saw my original post which I had totally forgotten about.

Edited By old mart on 10/06/2021 20:56:29