In a moment of weakness I decided to try a pair of these; let me say straightway, had I examined them closely in a shop, I would probably have browsed on. That's to say they may / not work, exactly, it all depends what you mean by "work"!
Normally retailing at nearly £40, I did expect something reasonable - you can get quite a decent Chinese engineers' stainless vernier protractor for that money....... What you get comes in the usual Chinese wooden case, contents unexpectedly made in Taiwan. At first sight possibly still convincing, although on closer examination, the scales are printed paint and stick on ali, and they look worth £7.50 at a pinch. The body of the instrument is hard plastic, and attaches to the planer block with two hinged feet (4 magnets, strong pull). The knife locates by a fifth magnet to the central "micrometer" stem.
Alas, the "micrometer" has a standard metric thread with a pitch of 1.5mm, so one division (1/10 turn) is 0.15mm or about 6 thou. In my opinion this is rather too coarse for the intended job. Further, the hinged feet create significant backlash, which gets hidden by magnetic pull. An attempt to zero the gauge to the surface of the knife block showed that the plastic body will distort under the load of magnetic attraction. Despite this, a fairly repeatable zero position was obtained by screwing down the "micrometer" to the point just before the holding magnets break free. The device is thus under a small compressive load, so could be reset to fix knives with a known projection (2mm, say) from the block, if they had either jackscrews or springs underneath, to keep the device under compressive load. Without a load on the device the accuracy of setting will include the backlash.You could always glue the feet to remove the backlash, and reinforce the frame if you thought it necessary (see next paragraph)
I remembered something similar tested by FW, (it was issue 112/p94-6) but this was planer specific with no moving parts. The tester said "knives within 2 thou, as good as using a dial gauge". Well, I have my doubts, but we'll see if this one can do as well in the next day or 2.
Normally retailing at nearly £40, I did expect something reasonable - you can get quite a decent Chinese engineers' stainless vernier protractor for that money....... What you get comes in the usual Chinese wooden case, contents unexpectedly made in Taiwan. At first sight possibly still convincing, although on closer examination, the scales are printed paint and stick on ali, and they look worth £7.50 at a pinch. The body of the instrument is hard plastic, and attaches to the planer block with two hinged feet (4 magnets, strong pull). The knife locates by a fifth magnet to the central "micrometer" stem.
Alas, the "micrometer" has a standard metric thread with a pitch of 1.5mm, so one division (1/10 turn) is 0.15mm or about 6 thou. In my opinion this is rather too coarse for the intended job. Further, the hinged feet create significant backlash, which gets hidden by magnetic pull. An attempt to zero the gauge to the surface of the knife block showed that the plastic body will distort under the load of magnetic attraction. Despite this, a fairly repeatable zero position was obtained by screwing down the "micrometer" to the point just before the holding magnets break free. The device is thus under a small compressive load, so could be reset to fix knives with a known projection (2mm, say) from the block, if they had either jackscrews or springs underneath, to keep the device under compressive load. Without a load on the device the accuracy of setting will include the backlash.You could always glue the feet to remove the backlash, and reinforce the frame if you thought it necessary (see next paragraph)
I remembered something similar tested by FW, (it was issue 112/p94-6) but this was planer specific with no moving parts. The tester said "knives within 2 thou, as good as using a dial gauge". Well, I have my doubts, but we'll see if this one can do as well in the next day or 2.
