Aquired a set of carbide gauge blocks

Hi All,

I have just received the set of carbide slip blocks/gauge blocks that I won on eBay recently and very happy I am too - solid carbide so no issues of rusting and bought them for the proverbial song.

However the box and the blocks themselves are covered in a thin layer of what is best described as 'gunge', I suspect that the box has been left open in a workshop environment (they are grade 1 under BS4311 so I believe they are workshop, not calibration quality) and I suspect that its just a layer of general condensed coolant and the like, however I want then clean.

So...I guess I could find a large container of something in the brake cleaner/degreaser department and dip them through that but I also contemplated running them (separately) through the ultrasonic cleaner. Maybe starting with a dose of WD40 and then wipe the excess off along with the gunge might work too?

I am concious that I should not be doing anything to the slip faces themselves other than the bare minimum.

I am sure that there should be an expert (or two) on this matter and I look forward to your advice (hopefully not conflicting!)

Simon

I guess it all depends upon what you are going to use them for. If you have a lathe and milling machine, then I doubt you will be more accurate than 0.0005", so having blocks that are certified to a precision greater than this is a bit OTT. As you say, you got them for a song so what the hec. Honestly, dip them in white spirit for a while and then just wipe them clean. If they are real carbide, then you will need diamond paper to do any real damage to them. Dropping them on the floor will do the most damage.

My advice, get on and use them before they accumulate another layer of dust.

Bob H

Well not really - the precision of the measuring instruments should exceed the expected working accuracy by a bit and, since gauge blocks are often stacked to come up to a final size thereby compounding their tolerances, you'd want a bit more precision than that.

Simon, congratulations on your set of slips, as Bob H says, white spirit and a bit of kitchen roll should do the job, a drop of petrol would also work. Bandersnatch - you are correct in what you say, but in relation to industry where the slips are used in an inspection department at 20 deg C,and where work is allowed to stabilise at that temperature. We are all working in sheds or garages where temperature can be anywhere between 0 deg C and 30 deg C . I think the precision of any slips, providing they wring together, will exceed any precision a model engineer could ever imagine.

Sounds an ideal candidate for the Ultrasonic bath.

MichaelG. [Very envious]

Absolutely. That's because their precision is considerably better than the half-thou that was suggested as being acceptable. About an order-of magnitude better (+/- .00005"  ) for a typical "Grade-B" set.

At that, if you wring 5 of these together (not unheard of) the tolerance stack-up is now +/- .00025" which is about half the precision that was postulated above as the limit for model engineers (not my words). I wouldn't call that "exceeding any precision a model engineer could ever imagine" actually.

But I'm happy with my Grade-B set

(Edited to get rid of an unintentional smiley).

Edited By Bandersnatch on 28/08/2014 21:46:43

Thanks all for the responses. They have been through the ultrasonic followed by being wiped clean with a microfibre clith as recommended by one of the manufacturers.

When I read through a document from the NIST about gauge blocks I understood that the tolerence for this grade is +0.15 μm to −0.05 μm so presumably worst case with 5 blocks would be 0,75μm which I think is much smaller than the fractions of a thou mentioned. However I am also well aware that the accuracy of my equipment and my own ability is exceeded by at least one order of magnitude by these gauges, but they are a beautiful piece of work and a pleaure to own them.

I have an ancient and rusty part set that I am happy to use as substitute parallels when needed so they do have practical uses in my home shope anyway

Simon