I bought a centring indicator (the cheap version) which arrived this morning so I thought I would offer an opinion on it.

This is the Chinese version of the 'Blake' instrument, doubtless not as well made – but is it good enough to be useful? A quick test showed it was capable of centering the bore of a workpiece to within about 0.002", maybe better on some workpieces than others (this was a very quick test!). That may not be as accurate placement as using a standard DTI but it is easier to set up and use with all the probes that are included. If there is considerable backlash in your handwheels I can imagine it would be more difficult to use – my mill isn't too bad but the adjustment method demands you continually reverse the feeds as you try to find the position of minimum movement of the dial pointer.

Some of the small blacked parts in my example came pre-rusted (!) but they cleaned up OK. The 'rotation-proof rod' actually fell off the little screwed stub it had on the end due to the fact it had been glued in place but without the rod being seated properly in the 4mm hole. I used a 4mm drill to clean the hole out and stuck it back with a drop of Loctite 638. So some (inevitable) niggles with QC as can only be expected I suppose within this price bracket. With those issues fixed it seems to perform adequately, though for how long I can't say. It does fulfill a need I had.

Chris

Edited By Chris Heapy on 29/05/2013 16:27:31

I'll tell you what the Chinese are brilliant at making – little wooden boxes. I must have half a dozen empty ones right now and they're far too nice to throw away

It does demand a fair amount of headroom, I guess you could minimise that by using a simple endmill holder (plain bore, screw in the side – fairly inexpensive as there isn't much to them). Failing that, make one from a blank arbour, again pretty cheap and you could cut it as short as possible.Either would get it as close to the spindle as possible, the DIY blank arbour being the best option (but more work)..

Edited By Chris Heapy on 29/05/2013 22:02:40

I don't have too much stuff – just too little space

Yes, the bandsaw hinges upwards when I need to use it horizontally, but I can also use it in the vertical position using springs to tension blade.

I tried to make a video of this center finder in operation (although I really needed 3 hands to do it so it's a bit wobbly!). The video starts with the workpiece already aligned as best I could – less than one division movement, the workpiece is just a scrap piece of aluminium with a counterbore machined into it.

Then I move the piece 0.001" on the handwheel dial to observe the difference on the indicator dial, and attempt to move it back again (difficult with the backlash in the handwheel – and whilst trying to film the whole thing at the same time). Anyway it was obvious that 0.001" movement causes a significant change in the deflection of the needle. I think. Sorry about the crap commentary but my voice always sounds terrible on vids like this.

Edited By Chris Heapy on 12/06/2013 14:12:50