Hardness tester weights

M

Marko Veselinovic

Joined
Aug 3, 2020
Messages
32
Hi, I have recantly bought a used hardness tester. Price was fair, condition looks good, and I can`t buy a new one here in Serbia, nobody is importing/making them.
The tester in qustion is " ŠKODA RB1-220V "
Problem is that somebody removed and lost the weights that go in the back.
As far as I know these weights are meant to be changed depending on what measurement you want take, obviously I am intrested in Rockwell C scale.
The dial on the tester has the C scale marked on it, and the diamond looks to be new and for the HRC.
I know it is a long shoot, but does anybody have the same tester?
And can I determine the needed weight?
I have heard you calibrate them by measuring the force, can somebody explain this further and in as much detail as they can?
And what is the force in KG for measuring HRC, and what weight scale should be used to mesure it, what are the tolerances?
https://imgur.com/0uz3Y2b
https://imgur.com/4qC20di
https://imgur.com/sjKNYdg
 
I'm sorry to tell you that you have a great looking door stop.

Without the weight hanger and three weight set it will be very hard to get accurate readings. The hanger has a certain weight, and the weights are a specific percentage of the rating weight. You can buy a set that might or might not work for around $500-600 USD or 3500-4200 Kuna. It is a gamble if they will fit and if they will work. I would have the person who sold it really try hard to find the weights.

The alternative is to have someone with a similar unit weigh their hanger and three weights (150K) and try to replicate the hook and total weight with a steel pipe and lead shot. I did this for someone a while back, and it sort of worked, but they ended up buying the proper weights and hanger.
 
Well I did not pay much for it, I knew about the weights missing before buying it...
It does have the hanger and the part that interacts with the oil damper, just the actual weights are missing, which are nothing more then steel bars with a hole, I could make them on a lathe easely, but the qustion is how heavy shoud they be.
Best thing would be to find a manual or somebody with the same tester, I have contacted multiple people from the Czech Republic (this is where it was made) I might be able to find the info.
Second option is to calibrate it myself, using a load cell to mesure the force, trying difrent weights until I make it right.
HRC requires 150kg load on the diamond indenter.
Even if I find info on the weights I will need to calibrate it using hardness test blocks, basicly the weights do not need to be exact to the gram.

I might be wrong here just to say, I am not an expert this is why i have posted here.
 
Thanks, I will send them an email. I do not know how I mised this company in many google searches I have done. I don`t think todays Skoda would be of much help, if I am not misteken they just cary the same name not much else.
 
Well things seem to be going better then I tought they would.
I have found the original user manual, trough the help of a Czech knifemaker who has the same hardness tester.
I have a PDF so if anybody ever needs it just email me ( mvknivesofficial@gmail.com )
Now I know exatcly what I am missing (circled blue on the pic) sadly the manul does not say how heavy the weights are, but the guy who gave me the scan of the manual promised to messure them for me :)
Radek if you ever read this thank you once again.

https://imgur.com/UgBkWsG
 
Around 7.3kg of weights for HRC
This was made in Czechoslovakia in the 1980`s I was sceptical it would be some standard 1:25 like you mentioned.
The guy measured the 4 difrent weights you need to do HRC, HRB and HRA.
He gave me numbers to 0.1 of a gram :)
(originaly you would get six, but two of the weights are used for Brinell, which you need a microscope to read, soo I wont even bother making those)
Aditionaly I went back to the place I bought it, showed them the manual which has detailed images and the guy recognized they had the weights, they were kicking around the shop but the they didn`t know what they were for.
(they say they got the hardness tester with some other tools years ago, and never used it)
There is a small chance they find them, but it`s slim, the shop is huge and full of tools...

I also triple checked, with the help of the drawings from the manual, that nothing else is missing. This gave me confidence I can make this a good measuring device.
 
Here is an update for my Skoda RB1 hardness tester i bought without weights.
It was sitting for a long time, and some dirt and rust got inside so I took everything apart and gave it a good clean.
I machined new weights that are basically same as the factory ones, not only in weight but also shape (thanks to a guy I found online with the same tester)
I got a calibration block of known hardness and successfully calibrated it.

It was a loot of work, these old testers perhaps are not as accurate as the new digital ones, but one like that is out of my budget.
With 3 measurements taking the average number, I am more then confident it is accurate down to 0.5 HRC or more.
So at the end I think it was worth the struggle, and as bonus now I know how one of these functions exactly : )

https://imgur.com/UkYnE09
https://imgur.com/eF0FOgL
https://imgur.com/1qlykEk
https://imgur.com/9EpUyIP
 
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