Stainless Steel Cylinder vs Ruby Cylinder Stylus

[MUlissi]

Hey folks,

I hope I'm putting this in the right place, please correct me if this question belongs somewhere else.

I've used a lot of different styli at different jobs, but I've never been in the position of deciding which one is the best use case. I'm at a crossroads where we need to order more cylinder styli so that we don't wind up in a spot with no measuring tool because what we have breaks, gets bent, etc.

I tried searching online and I found articles talking about best use for ball tips relative to use case, but I couldn't find anything about cylinder styli.

I'm checking stamped automotive parts. Some are sheet metal thin, some have a bit more heft. I tend to use a ball tip for the thicker parts, and we have plenty of those left from my predecessor.

What are the pros and cons of using a stainless steel cylinder stylus vs using a ruby cylinder stylus when checking sheet metal parts?

Thanks again

[Matthew D. Hoedeman]

You must have the cylinder perfectly perpendicular or your data will be bogus. I check sheet metal all day, every day, from 0.020" to 0.475" thick. I use a ball on it all. If you are worried about checking the edge of the sheet metal, do it 'right', use a surface sample hit so that the ball always touches at the exact same depth on an actual part.

[MUlissi]

Surface sample hits every time, and I let the software help me decide on the proper angle of approach.

[William Johnson]

Or do 3 sample hits so it will level on surface before measuring.

[louisd]

If you are checking items with low relative material hardness: plastics, glass, copper, brass: a SS or any steel cylinder will work well.
If you are checking bare aluminum, you need a zirconia or silicon nitride stylus, NO RUBY.
--If the aluminum is treated (Chemfilm, anodize, etc) you can use ruby. Bare aluminum and rubies apparently produce a reaction and the ruby will collect oxidation all over it from the aluminum.

If you are checking steel or other alloys: ruby
There are other stylus materials for other exotics.
Cast iron is also super abrasive on a ruby, both links below recommend Zirconia (ceramic)
Some info from the pro's: https://www.itpstyli.com/Resources/Materials , https://resources.renishaw.com/en/de...lection(33232)

[Ego Murphy]

Hoedmann replies,
LouisD replies,
/thread