Which surface plate should I get?

[Canadium]

I have only a small 12X9 surface plate that seems too small for most things I want to do. Like checking the precision of my old Kurt 6 inch vise (about 17 inches long). I'm ready to spring for a new surface plate but can't decide if I should get a 24X18 or a 36X24. I would go for a grade B black granite as Starrett types are needless to say beyond my price point. The smaller size is much more affordable and at about 150 pounds should be easier to transport and set up in the shop. The larger size will be stretching my budget and at about 375 pounds will be many times harder to transport and setup in the shop. Don't know if having a ledge on the plate will matter? How often does one need to clamp things to the plate? I was considering getting one used but my impression is that when it comes to surface plates, used means badly abused, worn and inaccurate and not necessarily cheaper. Is the bigger plate worth the extra trouble and money???

 

[Former Member]

I'm on my second plate which is a 36x24 (upgrade from a small one), reason for purchase, friend was retiring and sold it to me cheap (practically gave it to me).

Pain in the a$$ to move about 500lbs but here is whats great about it.

Its big.
Lots of area to measure on.
Stable because of the wt.

This falls under wish I got one a lot earlier.

BTW look used they come up in great condition and are generally a lot less costly.

 

[Susquatch]

Mine is 24x18 with no lip. Never needed the lip and never needed bigger. But I'd take bigger if it fell in my lap.

I dunno if I'd be too worried about abused. Good ones show up regularly. It's just a matter of being fussy and patient.

Another member and I tried to buy a really big one a while back. We were going to break it up into usable sizes but the seller backed out of the deal.

I'm still open to a deal like that if you ever find one.

 

[RobinHood]

Get the biggest you can handle / afford. More is not always better - except in this case. Right now you are talking 17” to check your vise; tomorrow you may have a 18”x12” part that needs checking… it’s nice to have a little extra real estate around the part you are trying to measure.

 

[thestelster]

I have an 18x24, and I find it adequate for smaller items, but if you want to check mill vises or those sizes, you need enough surface area to move a height gauge or surface gauge all the way around it with its arms and indicator out from from the body.

 

[Rauce]

A lip makes it easier to move the plate around or pick it up.

I have a 36x24 plate that was cheapish used and came with the stand. The stand was the perfect height to slide the plate off into the bed of a truck and then back onto the stand.

Because the precision of my plate is unknown I have thought about getting a new smaller 12x18” plate to use for more precision work.

To be a grade B a 36x24 plate needs to have an overall flatness of 4 tenths. Even if it’s worn and it’s double I would say it’s still going to be fine for most home shop purposes in my opinion.

 

[Canadium]

Thank you every one for your thoughtful responses! Consequently I found a second hand surface plate on kijiji that I'm very happy with! Brought it home yesterday! Its a Mitutoyo 24X36X6 Grade A in almost new condition. Weighs about 600lbs!!!

 

[Mcgyver]

very nice! As very few will have the tools to quantify wear or correct on a surface plate you have to be somewhat cautious with used....but if it looks super clean and is in calibration I think you are good to go. 18x24 Starrett pink grade A meself, no lip, and its always done everything I've needed it to. The imports are an option and likely good enough for anything we' re likely to do, but I believe the certs are a work of fiction and do notice different printing patterns from different parts of the plate when using them for scraping.

I'm envious of having the space and material handling capability for a plate like that, a great score!

 

[Dabbler]

My good plate is an 18X24, but I wouldn't kick a bigger plate out of my shop. I find the busy bee plates (12X18) to be fine for small parts and general use, saving wear and tear on my good one.