Surface plate and straight edge auction find.

[jwearing]

I spotted a 24x36” iron plate on my 24x36x6” granite plate. When I tried to lift it, the suction was enough to lift the granite plate off its base. That’s about 500 lbs.

With my 12x18 I found you can pull upward lightly, it will stick but just keep pulling lightly, if will break free in a few seconds. Pulling super hard doesn’t seem to help.

 

[TGTool]

I'm just imagining a 12 x 18 surface plate zipping off the granite like an air hockey table.

 

[neilho]

If you're wanting to save them, a razor blade can scrape rust off well without harming the scraping. It allows for minute examination of what ya got without diving into a full rescrape and allows a better view of what's there.

I'll disagree with any sand/bead blasting as a cleaning method. It leaves just enough media embedded in the iron to dull any kind of scraping tool. Take the rust off, gently, just for evaluation purposes.

 

[JST]

And you are going to have to take off the texture it leaves, which may mean digging in farther to the whole surface than you might have if you did not bead blast it. Might make a lot more work.

 

[Freedommachine]

Update:

@neilho was onto something there. The razor blade worked extremely well, just peeled the rust right off.

I was shocked how well the small plate cleaned up. It does have pitting though.



Camelback


The tall parallel was scraped on one face, planed (sp?) on the other.

And the large surface plate... it WAS scraped!



I cannot believe someone sent this stuff to an outdoor farm auction.

I will update on the other straightedges once I get them cleaned up.

 

[Freedommachine]

The long parallel was ground on both faces. It's a little beat up but it'll be ok.



The 2 railroad rail looking ones were both scraped on the largest face, all other faces were crudely machined.




I'm thinking I will give them an evapo-rust treatment and a liberal coating of LPS-3 until my shops capabilities and time allow me to give them proper attention.

Edit: except for the large plate. I would like to weld up a trunnion/cradle type thing on wheels that I can mount it in. Would it be a bad idea to leave it supported that way?

 

[dcsipo]

The long parallel was ground on both faces. It's a little beat up but it'll be ok.

View attachment 396468

The 2 railroad rail looking ones were both scraped on the largest face, all other faces were crudely machined.

View attachment 396469


I'm thinking I will give them an evapo-rust treatment and a liberal coating of LPS-3 until my shops capabilities and time allow me to give them proper attention.

Edit: except for the large plate. I would like to weld up a trunnion/cradle type thing on wheels that I can mount it in. Would it be a bad idea to leave it supported that way?

Not sure, but the plates typically have dedicated support points; make sure that they stand on the points and not hanging on the edge or resting on the ribs or something inappropriate.

 

[Freedommachine]

Not sure, but the plates typically have dedicated support points; make sure that they stand on the points and not hanging on the edge or resting on the ribs or something inappropriate.

Okay, that sounds like the safest option anyway. After thinking about it for awhile - even if this plate was designed to be lifted and placed against a surface being scraped - it would not make sense to store it that way. I will have to build a 3 point stand for it.

 

[Richard King]

Today i bought 2 SE'S on a local machine shop auction a 48 inch camel back for 40.00 and a 72 inch prism for 26.00. i think i'll cut the long one into 2 or 3 pieces. then sell them on eBay.

 

[dcsipo]

Today i bought 2 SE'S on a local machine shop auction a 48 inch camel back for 40.00 and a 72 inch prism for 26.00. i think i'll cut the long one into 2 or 3 pieces. then sell them on eBay.

A 72" prism? that must be either thick as a brick or floppy like a wet noodle

 

[TGTool]

A 72" prism? that must be either thick as a brick or floppy like a wet noodle

Actually, I'm not sure a 72" straightedge is such a dumb idea. It's true that if you held it by the ends, the middle or even the airy points you could measure the sag. But if you're nesting it in a dovetail anywhere close to the prism length (and assuming that the way surface isn't completely catywompus) it gets support all along its length so the opportunities for sag and inaccuracy are only between the contact points. The closer the work surface is to correct, the less the prism sag matters.

 

[dcsipo]

Actually, I'm not sure a 72" straightedge is such a dumb idea. It's true that if you held it by the ends, the middle or even the airy points you could measure the sag. But if you're nesting it in a dovetail anywhere close to the prism length (and assuming that the way surface isn't completely catywompus) it gets support all along its length so the opportunities for sag and inaccuracy are only between the contact points. The closer the work surface is to correct, the less the prism sag matters.

I buy that, but it must be a PITA to keep it straight over time. I can only think of having it hung by the end as the only option. Not sure if using a 72" prism has any advantage over using a shorter one with overlaps. Someone thought it was an excellent idea So it exists. They must be rarer than shoes for snakes.