Cheap Chinese Hardness Testers

[revilla]

What are people's thoughts on this?

https://www.aliexpress.com/item/32962696790.html?spm=a2g0o.productlist.0.0.3231583dEdYocL&algo_pvid=8344d20c-bca1-48bf-b0b7-c60de235c77e&algo_expid=8344d20c-bca1-48bf-b0b7-c60de235c77e-0&btsid=c06f1273-ab74-4ff7-8ebd-4b6850efb101&ws_ab_test=searchweb0_0,searchweb201602_10,searchweb201603_52

OK, so realistically it's clearly a cheap Chinese ripoff a much more expensive product which is probably an awful lot better.

Really good Leeb testers sell for £1500-ish. This is ten times less. So it's not going to be the bees knees, for sure!

I seem to be getting involved in a lot of K Series builds lately and often have the need to get a head or block tested for hardness. I'd really like to be able to test them myself. I'm not looking for a precise hardness number, just a go-no-go decision. I've got a couple of heads in the garage that have been "properly" tested and all of the heads I've had tested that have been good have come back around 115 Brinell. 95 is considered an absolute minimum for a rebuild. I've also got one had which has clearly gone soft and has some indentation round the fire rings.

I'm wondering whether one of these would:

• Give vaguely-reasonable, repeatable results on the hard heads I've got.
• Give a significantly lower, repeatable result on the soft head.

If so it doesn't really matter how accurately the calibration is, I can use the readings of my sample heads as my own scale of "hard" and "soft", so long as it can tell the difference and the results are repeatable. If a head I test comes back close to my known "hard" reading, it's probably OK. If it's moving towards the "soft" reading I need to worry.

They do offer returns, so if it turns out that it gives wildly unpredictable readings or can't tell the difference between my hard and soft heads then in theory it can go back, although the practicalities of that to China may not be straightforward.

Worth a punt, you reckon? Or save my money and stop being silly?

 

[Mechanical Moz]

As you say, with cheap digital measuring equipment it's the repeatability of the individual units that often isn't very good.

Could you not fashion your own hardness tester?  Something that applies a known force for a known time through a known size stylus.  A weight, a lever and a ball bearing together with a depth mic to measure the indent might work well enough just for relative measurements.

[revilla]

It might work, but it sounds fraught with possible errors with home made kit to me. In theory the rebound method sounds simple enough for the probe to measure; fire an indenter at the surface, measure the ratio of the rebound velocity to the impact velocity. An induction coil around it and a bit of microcontroller circuitry to process the signal. Somehow doesn't sound like it needs to cost £1500 to be reasonably accurate. But I could be wrong.

[7 wonders of the world]

a few used options on fleabay, may also be worth looking at dealers who deal in good used engineering equipment - used to be a good one on Attercliffe road in Sheffield - cant for the life of me remember the name though.

Must be some in Brum and Coventry too though.