Small Cast Iron Surface Plate

[TomKro]

There's been a lot of talk about surface plates lately, so I thought I'd post a pic of my latest Craigslist find.
It's a 12 x 12 plate in pretty decent condition. It had a couple of tapped holes, which I wasn't crazy about, but for $40 and a short Saturday drive, I couldn't resist.



The first pic has my buggered up soft jaw sitting on the plate, but that's another story.
My only real point is that there's some pretty good old stuff out there, you just have to be patient if you're on a budget.
I'm not poo-pooing low cost alternatives. Sometimes folks just want to get this stuff out of their basement.

 

[Ulma Doctor]

Sweet Pick!!!
Looks like it's in pretty good shape:thumbsup2:

don't be too concerned about the holes, a light stoning of the areas surrounding the holes will show any high spots.
if you are lucky enough to have a straight edge or something really flat , you could then see if there are any defects or high/low spots near the holes or anywhere else on the plate.
a parallel, 1-2-3 block, a large tool blank or other precision ground items could be utilized as well to different degrees of accuracy.

you could, if you were so inclined, to map and sweep the surface of the plate with a test indicator.
this will give you a pretty accurate survey of condition of the plate.
if you are lucky enough to have a friend with another known good ,flat plate you could blue up your plate and use his plate as a master. then re-scrape your plate to the master's flatness.
like this video:
https://www.youtube.com/watch?v=O2nyrSq0tY4

nice find
good luck!
mike)

 

[visenfile]

Looks like a great find. I would have grabbed it if priced right.

 

[The Liberal Arts Garage]

Just another " Yes, but" . A foot square plate is a good aid with sandpaper to touch
up small parts, it's easy to re- flatten it when necessary. Don't "poison" a good flat
piece of granite........BLJHB

 

[Wreck™Wreck]

Why exactly do you need a surface plate at all?

 

[TomKro]

Wow, this is resurrecting an old thread. Forgot I posted it.

It could be used for measuring up small items, or could be used for a lapping plate. It's best for taking pictures of small parts to provide the illusion of technical competence. If he has a surface plate, he must know something...

It would be used for a lot more if I didn't have it buried on my bench. Total disaster down in the basement - and no time to pick up until after Christmas.

Excellent timing as a reminder. Tomorrow at work I have to help a co-worker re-set one of those fancy laser surface measurement arms. Maybe I'll bring it in and see just how flat it really is.

TomKro

 

[Uglydog]

Just another " Yes, but" . A foot square plate is a good aid with sandpaper to touch up small parts, it's easy to re- flatten it when necessary. Don't "poison" a good flat piece of granite........BLJHB

It's your plate.
Consider a piece of plate glass or a lapping plate and some Cottons.

Edit: not "Cottons". Should have written "Clover" lapping paste.
I really enjoy lapping, something therapeutic about the process. I am fortunate to have been given a very large unused vintage lapping plate. Note: that's different from being good at it!


Daryl
MN

 

[joshua43214]

Why exactly do you need a surface plate at all?

I think a better question for most of us would be, "why exactly do you need a quality surface plate?"

I have two of them. A small cheap one from Shars that I stick sand paper to and use as a lapping plate. It also doubles as a door stop, a gluing weight, and a base for my Sartorius balance. This in my mind is a perfect use for a small cheap surface plate and is a fine tool for the hobbyist who will need to lap or polish things flat from time to time.

I also have an 18" x 24" one I got on sale with free shipping from Enco. I do quite a lot of "cut to the line" and "drill on the mark" type of work, so it gets a decent amount of use. It does nothing my mill table would not do just as well, only my mill table is usually covered in a vise and swarf...

I think many of us can find a use for one. I think very few of us can get any worth from a grade A or AA plate though.

 

[Wreck™Wreck]

I think many of us can find a use for one. I think very few of us can get any worth from a grade A or AA plate though.

Well said. during all of the years that I have worked in this business I have found that having gauge blocks in order to check your tools to be more beneficial in the long run. This may cost a bit more then a small surface plate

If ones hobby is throwing every part on a surface plate and painstakingly measuring it, then enjoy.

What is the point of having a high end plate without the ability to set the tools, even if you own the most expensive Starrett height gauge available one would still stack the blocks at the desired dimension, remember that setting the tool to 0.000 at the base and then measuring a part 3.000" along the scale would impart some error. In order to measure such a part check it with a gauge block first, then measure the parts

Gauge blocks first, surface plates second otherwise an accurate surface plate is silly.

 

[Andre]

Wreck, I'm not an admin, but please keep in mind very few of us here are doing aerospace work. If a guy wants a surface plate, let him have one. I have three, and a fancy Starrett height gauge to boot. Why? Because I got a Starrett 255 and a medium size plate (at one time) certified to 15 millionths for $50.

Lets say I'm making a ball bearing spindle, which I am in the process of doing now, and I want to make sure the spindle I just turned hasn't bent when my butter fingers dropped it. I'll use V-blocks and an indicator on a known precision surface plate. Sometimes you just need, or want one.