# My 48" Straight Edge



## graham-xrf (Dec 3, 2021)

It arrived today wrapped up in an extravaganza of thick cardboard, miles of brown plastic sticky tape, and strapped down onto a pallet. All except the last 5cm or so at one end seems usable. I can see the scrape marks everywhere, and it's now the straightest thing I own.

*It has dovetail bevels!*
Underneath, it stands on three little steel balls set into the casting. One thing that I don't remember being in the description is that one edge is 45° beveled on the underside, and the other edge is beveled at what looks like 30°.

*The rusty end.*
A bit tragic, but the last two inches at one end seems to have been left exposed. Once the rust is knocked off, the pitting looks too deep to fix, unless it can be repaired with epoxy, and scraped back in. To do anything to the straight edge as a whole will require a granite at least 48" diagonal, but I may not need to do that yet. The rest of it looks OK to check out the ways on a 36" South Bend.

*It's heavy!*
I can just about pick it up, but not so easily move it about. I protected it at the edge of the (steel) benchtop with cardboard, and then lifted the other end. Clearly I have to contrive some sort of "dangle it" arrangement to be able to gently set it onto, or up against, anything one wants to check out. Given I can actually pick up the 36" South Bend lathe bed, I kinda wondered if it would be easier to dangle the bed onto it. Duh! Silly notion, surely! 

So, such as it is, I now have a main reference for most of what I want to be doing. One day, it might get a refurbishment makeover, but for now, I can just use it.
I don't know how deep that rust pitting is on the end, and I am open to any suggestions about what one does about stuff like that, short of a regrind and a scraping in.


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## JRaut (Dec 3, 2021)

Now you just need a 48" granite plate to check that it's flat!


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## Ulma Doctor (Dec 3, 2021)

a wipe with phosphoric acid on a rag will take care of the rust


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## graham-xrf (Dec 3, 2021)

Ulma Doctor said:


> a wipe with phosphoric acid on a rag will take care of the rust


I get it that rust volume expands up higher than the surface, and once we dissolve it away, the pits depths will be below the original surface, but there seem to be some areas between the pitting that might be up to the level of the original scraping. I had thought I could put some JB-Weld on it, very like the way one would put filler on a car, then scrape it back, as a kind of "repair".

At least for now, 36" fits onto 48" without needing to use near the rusty bit at the end.


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## woodchucker (Dec 3, 2021)

I would put a paper towel with evapo rust on it.


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## FOMOGO (Dec 3, 2021)

I think just the fact that you know it's there solves most of the problem. There are bound to be areas left after cleaning (as you mentioned), that are at, or so close to original, that it will have little, to no effect on it's use. Cheers, Mike


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## Ulma Doctor (Dec 4, 2021)

thankfully low areas are not of much consequence, unless there are vast areas of lows 
40% bearing is all that is required for most work as i remember


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## C-Bag (Dec 4, 2021)

I know it never ends but you need a set of tool room stones to get rid of any present or future burrs.


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## graham-xrf (Dec 4, 2021)

C-Bag said:


> I know it never ends but you need a set of tool room stones to get rid of any present or future burrs.


As it happens, I did stone it gently with my medium grade slip-stone, In the first seconds, I found two "events" near the edge which fortunately rubbed off straight away, and the stone then started that no-cutting feel sliding action where it was only shining up micron high regions.

I know the stone was not one of a precision ground pair, like Robert Renzetti makes, but I had made flat  by it rubbing against a flat diamond hone. The diamond plate is about 3/8" thick. I had checked the stone against a 6" glass flat.  The stone, of course, clogs up immediately on the rust at the end, but when I got it to slide about, and clearing the rust with an alcohol wash, I could see the extent of the pitting at the one end.

My quick-n-dirty test using a 0.0005" indicator on a base, checking across a local gap of about 100mm (4") to the DTI shows no real movement as I slide it about, leaving me guessing the local flatness is somewhere around a tenth and maybe two tenths, but when we get into the rust pits at the end, the DTI  moves about over a 0.001" to 0.003" range. If that's how deep the pits are, it is fixable by scraping, which, for me, would require a granite big enough to spot the whole surface.

I do have a variety of stones, flattened against the diamond plate, and they act exactly as precision-ground tool room stones would, except they were not from a session on a surface grinder. I tried one on a 123-block ground surface, and all that happened was it showed up the micron ripple from when the 123-block was finish ground. I know I got there using hand-made kit, but by now, I do trust the result.

From the design of it, obviously arranged to sit on three ball-bearing mountings, with flat side up. it clearly is mainly intended for stuff to be brought onto it, rather than it being put up to a machine. Basically, it seems like a long surface plate. It is 48.8" long and 5" wide. The design is not "camel-back" style. How exactly it is going to be used to check out the ways on my South Bend is not yet fully clear to me.. Sure, if scraping the ways, then use it for spotting, but diagnostics might be something like moving a DTI along, using the straight edge as a base.


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## casey.little (Dec 4, 2021)

Looks like a piece of train rail! 


Sent from my iPhone using Tapatalk


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## C-Bag (Dec 4, 2021)

I too did the homemade tool room stone with a diamond hone on my small surface plate. It worked ok, but I could never get rid of the slight “edge dive” from pushing by hand. The centers are nice and flat but it’s really tough because of friction. I got a set of the smaller tool room stones off eBay and it’s crazy how good they work and how they have solved many problems I couldn’t before. Like a set of B&S machinists squares for a too good to be true price off eBay. In checking them they weren‘t square and I couldn’t see or feel any nicks. Stoned them carefully and bingo, good to go.


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## graham-xrf (Dec 4, 2021)

C-Bag said:


> I too did the homemade tool room stone with a diamond hone on my small surface plate. It worked ok, but I could never get rid of the slight “edge dive” from pushing by hand. The centers are nice and flat but it’s really tough because of friction. I got a set of the smaller tool room stones off eBay and it’s crazy how good they work and how they have solved many problems I couldn’t before. Like a set of B&S machinists squares for a too good to be true price off eBay. In checking them they weren‘t square and I couldn’t see or feel any nicks. Stoned them carefully and bingo, good to go.


That's a good result! 
I have seen a tip on a video saying that salvaging old wrist pins (gudgeon pins) from out of the pistons of the bigger diesel engines when they are being reconditioned, or scrapped, gets you the makings of a nice little cylinder square reference. Case hardened, precision ground, etc.


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## Dabbler (Dec 4, 2021)

that is a very nice straight edge!  (envy...)


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## C-Bag (Dec 4, 2021)

graham-xrf said:


> salvaging old wrist pins (gudgeon pins) from out of the pistons of the bigger diesel engines when they are being reconditioned, or scrapped, gets you the makings of a nice little cylinder square reference.


Hmmm, the largest Diesel engine I ever rebuilt was JD tractor and the wrist pins and pistons were reused. I have no idea how big a wrist pin is in an 18 wheeler or say a big crawler is but even though they are hardened they are not without wear. Now if you could find NOS or low time that would be something to look into.


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## graham-xrf (Dec 5, 2021)

Ulma Doctor said:


> a wipe with phosphoric acid on a rag will take care of the rust


So - some Coca-Cola then?  
I don't have any phosphoric acid as was once in the overpriced little plastic bottle of "rust eater" gel, but I do have various other kinds of acid, so I am thinking a little citric acid, or the classic mix of spirit vinegar with a spoonful of salt?

It also occurs to me (following my earlier adventures with nickel plating), that to plate on a couple of microns of nickel (that's about 80 millionths in inches), using the "wet cotton wool swab" method might make such rust damage never happen again.

Of course, taking reasonable care of it, smearing a film of that blue corrosion block grease from Lear chemical (or similar), or maybe some WaxOyl, and keep covered and stored in a dry place would work just as well. There is ACF50. Maybe even way oil is sticky enough?


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## Ulma Doctor (Dec 5, 2021)

graham-xrf said:


> So - some Coca-Cola then?
> I don't have any phosphoric acid as was once in the overpriced little plastic bottle of "rust eater" gel, but I do have various other kinds of acid, so I am thinking a little citric acid, or the classic mix of spirit vinegar with a spoonful of salt?
> 
> It also occurs to me (following my earlier adventures with nickel plating), that to plate on a couple of microns of nickel (that's about 80 millionths in inches), using the "wet cotton wool swab" method might make such rust damage never happen again.
> ...


yes sir-just about any acidic solution would be effective against the rust 

i haven't used nickel plating for anything other than experimentation, i would be very interested in the outcome

a smear of way oil would be good- you'll just need to clean the straightedge before each use 

there are many discussions about how to store straightedges properly when not in use
i'm a strong proponent of hanging them
but, i have heard argument that reference items should be supported on 3 points for storage as well


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## Dabbler (Dec 5, 2021)

@graham-xrf if you stick to  the organic acids, such as citric and acetic, they will chelate the oxides, but attack the metals hardly at all.  CLR and the other rust removers work on the same principle.  Stay away from muriatic and its sulfuric actid and copper sulfate and similar compounds  as these will attack and pit the base metal.  Sometimes they can be used, but carefully, and not in high concentrations.   

I'm refurbishing a D1-6 faceplate with rust on it.  The taper is rusted and it is a precision surface.  I'm going with a wipe on vapo rust with a non abrasive pad to remove the loose rust, then I'm polishing it out with 800 and 2000 grit wet and dry.


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## C-Bag (Dec 5, 2021)

My old 36” B&S camelback came with its original felt padded wood tray. But I keep it hung on the wall with the surface aimed slightly down and liberally coated with FluidFilm. That’s the only stuff I’ve found that will keep rust away here and it lasts forever.


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## graham-xrf (Dec 5, 2021)

Ulma Doctor said:


> yes sir-just about any acidic solution would be effective against the rust
> 
> i haven't used nickel plating for anything other than experimentation, i would be very interested in the outcome
> 
> ...


Camel-back straight edge stress-relieved castings, I have read, store very well when hung. This one, not being camel-back, has the 3-point hardened balls supports. They look to be placed apart at pehaps the Bessel points, and I think I will store it that way.

It seems to be set up such that it was scraped parallel to the supports, or maybe the supports were driven in afterwards, but however it was done, it does look like if it was put down on a level surface, the scraped surface would also be level. I will be checking this point soon when I have opportunity.

Where it is right now, though comfy enough, is not to be where it will finally be used and kept. I shelled out on it when I saw the deal come up, but my shop (outbuilding), though constructed,    , still needs it's floor covering added. Right now, in there, is only a school-style folding wooden chair, a trusty old Black & Decker workmate, a box of Pozidriv fixing screws, and a coffee mug.


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## graham-xrf (Dec 5, 2021)

Dabbler said:


> @graham-xrf if you stick to  the organic acids, such as citric and acetic, they will chelate the oxides, but attack the metals hardly at all.  CLR and the other rust removers work on the same principle.  Stay away from muriatic and its sulfuric actid and copper sulfate and similar compounds  as these will attack and pit the base metal.  Sometimes they can be used, but carefully, and not in high concentrations.
> 
> I'm refurbishing a D1-6 faceplate with rust on it.  The taper is rusted and it is a precision surface.  I'm going with a wipe on vapo rust with a non abrasive pad to remove the loose rust, then I'm polishing it out with 800 and 2000 grit wet and dry.


It will be a thing of beauty!

I have figured out that when irons and steels, perhaps excluding those alloys that have the assistance of chromium and suchlike, rust madly, and deeply if they have their micro-surfaces chemically exposed to air, such as when they have been treated by acids, or steam-cleaned, or recently cut. The the rusting gets going instantly unless stopped while it is still wet. After steam-cleaning, I saw my lathe bed turn orange in about 30 seconds!

It seems that the process can be halted by treating with neutralizing alkali, like sodium carbonate, or bi-carbonate. Simply put in boiling hot water for a while, "seals" the surface, they say, but I think it is the oxidation to magnetite, which if oiled afterwards, gives it the protection. It is absolutely true that if the surface is polished in the way you describe, it so reduces the exposed micro-surface area, that it resists rusting, even without further protection.

While the dark brown (oily) patina on the 4-jaw chucks that came with my South Bend 9 has it's vintage charm, I much prefer the look of (oily) shiny steel, especially the way it accents a piece of precision vintage iron that is also stating that it has been well cared for. I guess I just hate rust!

My first adventures with nickel protection was when recovering a countershaft spindle from the filthy rusty mess it had become from neglect.




Even a spindle inside what should have been swimming in oil, if left to stand long enough, takes a print in rust of where the oil should have been coming in.




.. and it's future will not ever be like the next picture ..




I have made an ad-hoc plating bath for it, out of plastic drainpipe..





So - for something as important as my 48" straight-edge reference, I may well use some nickel. I understand Robert Renzetti used some kind of low(ish) temperature silver solder to fill rust pits in a surface plate, and then scrape it back. A bit like old-school car bodies were "leaded". I am thinking that if the rust pits on the end of the straight-edge were treated this way, then all of the rest of it need not be scraped down to get it all below the depth of the rust pits.


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## Dabbler (Dec 5, 2021)

You might not need to treat the rust pits at all.  All you really look for is contact area, and in the number of contact points per inch.  Scraping has an averaging effect if done correctly, so missing a spot or 2 won't have much of a difference in the 10-20 rounds of printing/scraping.

If you solder fill, you have to be careful in wipe-downs, that you don't get anything embedded in the soft solder.  It can make your day turn bad, and quickly.

I'd clean it up first and print it on a surface plate before doing any refurbishment planning...


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## C-Bag (Dec 5, 2021)

Dabbler said:


> You might not need to treat the rust pits at all.  All you really look for is contact area, and in the number of contact points per inch.  Scraping has an averaging effect if done correctly, so missing a spot or 2 won't have much of a difference in the 10-20 rounds of printing/scraping.
> 
> If you solder fill, you have to be careful in wipe-downs, that you don't get anything embedded in the soft solder.  It can make your day turn bad, and quickly.
> 
> I'd clean it up first and print it on a surface plate before doing any refurbishment planning...


This is what is so tricky about all of this. The old axiom “do no harm” is so true. But the times I’ve messed that up through ignorance is maddening.


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## graham-xrf (Dec 5, 2021)

Dabbler said:


> You might not need to treat the rust pits at all.  All you really look for is contact area, and in the number of contact points per inch.  Scraping has an averaging effect if done correctly, so missing a spot or 2 won't have much of a difference in the 10-20 rounds of printing/scraping.
> 
> If you solder fill, you have to be careful in wipe-downs, that you don't get anything embedded in the soft solder.  It can make your day turn bad, and quickly.
> 
> I'd clean it up first and print it on a surface plate before doing any refurbishment planning...


OK - thanks for the tip! The very same caution would apply to games with epoxy in the rust pits.
I am already looking about (and saving) for a granite big enough to set it down on.

This is despite the videos by LookCreations showing how he "step printed" his way up from a 24" x 24" surface plate, and a 24" straight edge, to a 36", then using that for a 54", and I think ending up with a 72".


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## C-Bag (Dec 5, 2021)

graham-xrf said:


> This is despite the videos by LookCreations showing how he "step printed" his way up from a 24" x 24" surface plate, and a 24" straight edge, to a 36", then using that for a 54", and I think ending up with a 72".


YouTube is chockablock with contrary info. I’d love to show up with the crew that did the plate calibrations at Oxtools and have them check all those.

 I mean it could be possible but so are aliens, and Bigfoot.


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## Dabbler (Dec 5, 2021)

it is *possible* to stepwise get bigger and bigger, but as Connely says, it is a very advanced thing to do....


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