Surface plate use

[Mr. T]

I was scolded at work today for having aluminum on a surface plate. I'm not a trained machinist so there are certainly things I haven't learned yet. It just seemed odd that you aren't supposed to do that. Is there anyone who can explain this with a little more detail? How does aluminum damage granite when steel is ok?

Thanks

 

[G1K]

It can make marks on the surface plate, but as far as I know it'll do no real harm

Ryan

 

[Leaflessshadetree]

Simple rule. Avoid placing anything on surface plate unless it belongs there.

 

[dave89iroc]

Simple rule. Avoid placing anything on surface plate unless it belongs there.

agreed

 

[Kirbot]

Simple rule. Avoid placing anything on surface plate unless it belongs there.

This
But I hardly see a fundamental problem with aluminum

 

[Caman]

Unless this was some AA Laboratory grade surface plate(probably not even then?) I don't see anything wrong with inspecting clean aluminum on a surface plate. I've done it thousands of times and will keep doing it. How do they expect you to check an aluminum part without a surface plate?

 

[DocsMachine]

The surface of a granite plate is porous, kind of like concrete. Dragging aluminum on the surface can embed aluminum, not only leaving a bright mark (especially visible on black rocks) but potentially degrading the accuracy.

Keep in mind that in this case "accuracy" means, depending on the plate, fifty millionths of an inch. That's thinner than a fingerprint on glass.

The guy that scolded you may have been a bit overzealous, but it's very common in shops of all kinds for non-machinists (or any other employee) to treat a surface plate as any other flat surface. Klunking tools down on it, setting your cup of hot coffee on it, leaving your lunch on it, etc.

It doesn't take much mistreatment to reduce the accuracy of the plate, and if the shop is making high-end accurate parts, or even just doesn't want to pay to have the thing recalibrated twice a year, they tend to get a little zealous about it.

Treat them gently, keep them clean, don't put anything but the proper tools on it, and keep it covered when it's not in use.

Doc.

 

[Mr. T]

Simple rule. Avoid placing anything on surface plate unless it belongs there.

That's the thing. I was using it to scribe a length on four short lengths of 8020 that needed to be the same length. And then checking them against each other on a known flat surface. I wasn't using it to hold my aluminum coffee mug.

I was then told "you don't use aluminum on a surface plate."

 

[zkling]

That guy would probably poop a brick if he saw aluminum parts on the CMM

 

[Childiaugz]

Aluminium is soft and can leave trace amounts of aluminium on the surface plate. But if you aren't a trained machinist chances are you aren't using a high accuracy surface plate or in a clean quality inspection room.

I measure aluminium on mine all the time.

 

[joel63]

Aluminium is soft and can leave trace amounts of aluminium on the surface plate. But if you aren't a trained machinist chances are you aren't using a high accuracy surface plate or in a clean quality inspection room.

I measure aluminium on mine all the time.

I didn't know that.

Always something to learn on GJ.

Thanks.

 

[Zrexxer]

Ultimately, it doesn't matter if it makes sense or not, does it? Their surface plate, their rules. It's just part of keeping a job - any job.

 

[zkling]

The question is who scolded him and why. What was the reasoning behind the scolding.

 

[Mr. T]

The question is who scolded him and why. What was the reasoning behind the scolding.

He's tooling and I'm maintenance. I asked what it did and he pointed to a spot that to me looked like the rest of the plate. This thing is in a dirty tool room and feels like the surface of the moon already. I just said "Sorry, I was unaware that you should 'never use aluminum on a surface plate.'"

Ultimately, it doesn't matter if it makes sense or not, does it? Their surface plate, their rules. It's just part of keeping a job - any job.

In theory it's as much mine as it is his. It's owned by the company and we're both in positions that require us to use it. Although, his requires it more than mine.

 

[383 240z]

20 years ago somebody chewed his *** about it. Now he had the chance to be the "chewer" rather than the "Chewee". I inspect AL parts on ours 10 times a day and never a word said. Keith

 

[St-rider]

That's the thing. I was using it to scribe a length on four short lengths of 8020 that needed to be the same length. And then checking them against each other on a known flat surface. I wasn't using it to hold my aluminum coffee mug.

I was then told "you don't use aluminum on a surface plate."

Remind him that 80/20 is clear anodized so it shouldn't be an issue... unless you had the cut ends on the plate.

 

[Kracin]

Remind him that 80/20 is clear anodized so it shouldn't be an issue... unless you had the cut ends on the plate.

technically all aluminum is anodized if you leave it out long enough...

 

[RAYJAY]

That's the thing. I was using it to scribe a length on four short lengths of 8020 that needed to be the same length. And then checking them against each other on a known flat surface. I wasn't using it to hold my aluminum coffee mug.

I was then told "you don't use aluminum on a surface plate."

this is why..... scribe on surface plate


only use it to measure

 

[Zrexxer]

When you said you got "scolded," it was reasonable to believe that you were being scolded by someone who had business to do so... your foreman, or work lead, or supervisor, or whomever you report to.

If it's just a whiny coworker who has no business bitching you out, then there are many different ways to say "GFY."