Inexpensive (cheap) Surface Plate

[timo_gross]

For me glass is a good way forward - but don't drop it! I have a wooden frame and backing on a 18x12inch mirror which I have used for many years without breakage. If you break it buy another!

If a granite table gets dropped it will probably end up badly too. I did not know what "head stone" means, turns out School did not cover this (but google did).
I guess they are more expensive than a graded inspecton granite. I paid less than 150 USD for a small plate which is big enough for my use and just small enough that I can carry it.
Was offered a 2nd hand one for 800 USD a while ago. ( 1kilo at a little under 1 USD should have bought it, .... as a workbench .... )

 

[roncohudd]

Although I have had a Mill and Lathe for some time only since I 've retired have I found time to use them. I have built a wobble plate engine based on Elmer's design and found that it is a lot of fun along with being a challenge. I read the forum with great interest and admire the talent that I fear the young will never know.

But to the point of the post. I needed a surface plate, the granite plates while being time tested, proved to be a bit spendy. I did not want a metal plate, living in Arkansas were the summer months bring the "air you can wear" the metal would prove to be a pain to keep clean.

While driving home one afternoon, I passed by a monument company. I turned around and went in to ask about grainite. After explaining what I was looking for I noticed a few broken headstones. I asked about the stones. Most all had highly polished surfaces, at least on one side. Found a piece, broken. I bought the stone for $20.00. The stone is a bit thick at 8 inches, but warping will not be a problem. The usable surface is about 18 X 16 inches. The surface is smooth and for the work I am doing it will be perfect.

Just thought I would pass on some information, I ran a search, but could find any post for this, forgive me if you all have done this and it is old news.

Thanks for the forum and the vast wealth of information.

I have been lucky enough to have been gifted a great Standridge 29" x 24" x 5" great surface plate already sitting on a roll around cart. Last update was in 2007, but it's great for what I'm doing.

 

[roncohudd]

I have been lucky enough to have been gifted a great Standridge 29" x 24" x 5" great surface plate already sitting on a roll around cart. Last update was in 2007, but it's great for what I'm doing.

That is 18 x 25 x 5

 

[roncohudd]

That is 18 x 24 x 5

 

[william_b_noble]

surface plates, if you have time, are not expensive. since they are heavy, they don't sell well at garage/estate sales, for example. I have a 2X3 foot surface plate which I got from ENCO at a trade show (Enco was later bought by MSC). I had a coupon, they had a show deal and there was a sale and in the end the surface plate, delivered cost $0. I paid the truck driver $20 to get it to my garage for me, and a friend (now deceased) had the exact correct stand for it

 

[abby]

A piece of plate glass is good enough for most of us and a tip I saw somewhere is to place the glass on a suitable surface with a frame around it about 3/4" deep then fill with plaster of paris. This covers any sharp edges and makes handling and using much easier.
Dan.

 

[ShopShoe]

Just a FYI regarding glass. I have some pieces of 1/4-in thick plate glass I use for backing up sandpaper (and to keep from sanding on my surface plate.)

You can get a GOOD glass shop to sand the edges of your piece of glass. (This is not the home center or hardware store.)

You can also CAREFULLY sand the edges of your own glass. Use a rubber sanding block (easy to find wherever you buy auto body and auto paint supplies.) Use Wet-and-Dry sandpaper wet with water.

When I do this I cover my bench with a rubber mat and clean up with disposable rags.

(As with everything else on this forum, be careful with this whole process. You have to judge your own abilities and you use techniques described at your own risk.)

Just another "make a tool to make a ....."

--ShopShoe

 

[Steamchick]

I also have a small circular saw (table ~15in sq.) that serves as a surface plate when required.
Look at your machine tables. I doubt you can measure more accurately on a surface plate than you can machine...
The main plate of the Milling machine is probably your largest plate for a surface plate.
I am not adequately knowledgeable about how dimensions on a surface plate (variability associated with the surface flatness) translate to additional variability of the part mounted on a traversing deck beneath a milling cutter... but I guess if you measure on the miller - especially when the part is bolted-down - then machine, then that is as good as you can do...?
Any toolmakers able to advise?
Ta,
K2

 

[Mike Ginn]

Well said K2. The advantage of a glass plate for me is its portability and low weight. I have a cast iron surface plate which is never moved due to its weight but the glass plate moves from bench to my Workmate as needed. Polished tiles also work and can be picked up as single samples at the DIY stores.
Mike

 

[Poppy Ott]

I have four surface plates, funny how things accumulate. Two, one cast iron and the other a Starrett granite, see regular use and have permanent location in the shop. The other two are surplus to requirements and are in storage. In keeping with the title of this thread, I’m offering the two extras in expensively, that is really cheap, to anyone who wants one or both. Come get them and they are yours. The black granite one is 9” x 12” x 3.25”, and the grey 12” x 18” 2.5”. two ledge.

 

[Toymaker]

About 10 years ago I found a very nice hard coat anodized aluminum fixture plate, 12" x 19", complete with T-Slots, at a metal scrap yard, (Alan Steel & Supply Co, Redwood City, CA)
I bought it for the scrap aluminum price-per-pound, (sorry, I don't recall what that was). The plate has a number of scratches and dings on the top surface from it's previous life, but is nearly perfect on the bottom side, and measures flat on my mill to 0.001" in X & Y directions, top & bottom.

So, if you have a scrap metal dealer in your area that sources from a fabrication industry, you can sometimes find some fairly nice deals.

 

[grahamgollar]

It is common practice at sea to use a port hole glass for lapping the faces of injector nozzles. All ships carry a selection of these glasses and the Engineers just have to sweet talk the Bosun to acquire one!

 

[Ghosty]

It is common practice at sea to use a port hole glass for lapping the faces of injector nozzles. All ships carry a selection of these glasses and the Engineers just have to sweet talk the Bosun to acquire one!

This is where I got my first plate, then I had a scientific glass plate 18"x18"x2" that I had for many years until it disappeared in one of my moves
Cheers
Andrew

 

[william_b_noble]

it all depends on what accuracy you need. if .001 or .005 is sufficient then any sort of flat scrap will work, if .00001 matters then less so, and if you need to work in microns then you need a work surface that is to that standard. The last time I needed precision, I was fitting bearings to a replacement (used) differential carrier for a late model (at the time) 911. with a surface gauge and a surface plate I was able to confirm that the two parts were identical in the important dimensions to much better than .001, so no tedious shimming required. that was quite a relief

 

[dsage]

Several years ago I came across some 12 x 12 industrial ceramic floor tiles. They were flat right out the edge. I glued a couple back to back to make them less likely to snap. They are standing on edge next to the work bench and are easily picked up and put on the bench for quick requirements for a pretty flat surface. Such as for polishing on, layout of assembly pieces etc.
There are certainly lots to choose from at a ceramic tile flooring store.

 

[deverett]

My surface plate is the platen from a discarded photocopier. This sits on a plywood base lined with baize. I have a second one that I use for laying abrasive paper on when I'm trying to remove machining marks.

Dave
The Emerald Isle