PDA

View Full Version : Brass on Surface Plates?



Andre3127
11-22-2016, 12:54 PM
I have an idea to build a small squareness comparator out of a piece of brass. Will brass rubbing on a granite surface plate cause problems with deposits like aluminum does? Or will it just glide across?

I also have a ground steel surface pate which I will use it on, which is why I like the idea of it being brass. No scratches like a steel base stand/tool would.

enl
11-22-2016, 01:05 PM
My experience says that , yes, you may wear the brass and end up with deposits on the surface plate, at least with some alloys. The harder alloys of bronze might be ok, but I would insert hard steel feet (I think I picked this up from Tom Lipton's squareness comparator video, but not sure) ground flat and planer.

Forrest Addy
11-22-2016, 01:08 PM
Not really. If you forceably drag a corner, it might made a dull mark but no harm or bump will damage the plate. I'd be more concerned with wear of the brass base and the expansion rate difference between brass and steel parts.

Andre3127
11-22-2016, 01:30 PM
Not really. If you forceably drag a corner, it might made a dull mark but no harm or bump will damage the plate. I'd be more concerned with wear of the brass base and the expansion rate difference between brass and steel parts.

Do you mean between the brass base and parts to measure, or the steel surface plate I mentioned that this gauge will occasionally be used on?

I will probably add in a walnut wood thermal insulator, and if needed I could always attach a steel plate on the bottom to retain the classy look and patina of brass and improve durability.

Andre3127
11-22-2016, 01:33 PM
My experience says that , yes, you may wear the brass and end up with deposits on the surface plate, at least with some alloys. The harder alloys of bronze might be ok, but I would insert hard steel feet (I think I picked this up from Tom Lipton's squareness comparator video, but not sure) ground flat and planer.


Tom Lipton actually used carbide feet on his.

I think it's a more common alloy such as 360. I don't know, they were old 2" diameter screw machine drops my boss gave to me. This will be a small gauge of two I am making. The larger one will use a finer resolution indicator and reserved for inspection, this brass one will use a half thou test indicator for shop use.

Joel
11-22-2016, 01:40 PM
As the apparent voice of dissension, I would suspect that in a home shop environment, you needn't be overly concerned with wear, assuming the base is of any reasonable size.

Mcgyver
11-22-2016, 01:53 PM
As the apparent voice of dissension, I would suspect that in a home shop environment, you needn't be overly concerned with wear, assuming the base is of any reasonable size.

I think the preoccupation with what contacts a surface plate and its wear comes from the endless complaints of the commercial guys on how surface plate paraphernalia just does not last :D (not)

I say steel or cast iron, ground or scraped are best, but end of day, make it out of whatever you like, us it your whole life then give it to a kid to use for all of there's....and it'll still be fine :)

enl
11-22-2016, 02:09 PM
Tom Lipton actually used carbide feet on his.

Ah. Carbide. It was I while ago and all I could recall was hard material.


I think it's a more common alloy such as 360. I don't know, they were old 2" diameter screw machine drops my boss gave to me. This will be a small gauge of two I am making. The larger one will use a finer resolution indicator and reserved for inspection, this brass one will use a half thou test indicator for shop use.

That answers the question right there. You have the material, test it to see if it marks up the plate. You could even see how it wears. I tend to agree that for occasional use, wear won't be an issue. I have a base of two of aluminum that do see the surface plate once in a while, but the bases are holders, not providing a reference. I have left brass marks on the granite with scribe handles several times, which is why I can say that, yes, at least some brasses will mark the plate.