Shop Press Brinell test

[Cascao]

Update: After taking photos from impressions and converting pixels to mm my measurements fall inside expected for each material. Good step but still there space for improvements.

[tonyfoale]

If you continue with your own made indenters there is a simple way to do better than using STEEL ball bearings. If get an old or broken carbide milling cutter of the right diameter you can grind a hemisphere on one end and use that. The carbide is harder than steel balls.

I found out recently that you can buy carbide balls, they are not expensive. I got a packet of 6 mm diameter for my drop test device.
BTW as I mentioned I did get around to making an electronic version of the drop tester.

Click for full size

I'll make a post with full details sometime soon.

[tonyfoale]

Cascao,

It has been some time now since you last posted anything on this. How have things progressed?

BTW my electronic version of the drop tester works very well and there have been a few people who have copied it.

[Cascao]

It is hard to meassure with precision the diameter of impressions.
The method of taking pictures correcting the picture scale and meassuring picture can include many more variables and incetities to the end result.
Stopped developing this since was having trouble to produce trusteable repeteable results.

[tonyfoale]

It is hard to meassure with precision the diameter of impressions.
The method of taking pictures correcting the picture scale and meassuring picture can include many more variables and incetities to the end result.
Stopped developing this since was having trouble to produce trusteable repeteable results.

That is what I expected. The Rockwell system of measuring the indentation depth with a gauge as you apply the load always seemed to me to be a much better system for a DIY project. With the Rockwell test you apply an initial small load to take up backlash and take up the effects of any dirt on the surface. This becomes the reference position and then you add the full load and measure the vertical movement. The actual Rockwell machines use a lever system and weights to get the load but you could use a pneumatic or hydraulic system to apply the load directly. FWIW Here is a picture showing the innards of a Rockwell machine. Vickers machines also use a lever system for loading.

click for full size