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Large Straight Edge Questions

M.B. Naegle

Diamond
Joined
Feb 7, 2011
Location
Conroe, TX USA
In the spirit of Lurk's topic working over his larger standards, here's another one for you guys!

With all the eventual scraping jobs I have on the to-do list, I have a number of straight edges on my want list, which include some long ones for checking mill table ways and lathe ways. I know there are ways to do them with shorter standards, but I'm a glutton for punishment;).

SO, I found a 72" Brown and Sharpe at what I thought was a very resonable price, and shipping ended up being an even better deal, so here we go!
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With packaging, it came in at 93 lbs. My young frame can move it around with little trouble, but holding it at a 45 to print a lathe's V-way will likely be difficult, so I plan on making a portable hoist that I can support it with.

It's pretty grimy but the face is in decent shape. I don't see any wear, damage, or excessive corrosion, and it looks like the most recent scraping was professionally done. I plan on eventually getting a larger granite plate at our shop which I'll be able to use to calibrate this, so in the mean time I'm going to give it a light stoning and trust that the surface is usable. While I'm cleaning it up, I plan to give it a new coat of paint too. I'm thinking grey with black lettering would do it well.
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A few questions for you guys:

I plan on making a cart to store and transport my larger straight edges. I'm thinking a flat bottom cart long enough for an 96" straight edge (still on the want list), and 12" wide. I'd like to store them face down to protect them, but as the cart won't exactly be a flat surface (relatively), If I support the straight edges at 1/3 in from the ends, will that negate the possibility of them twisting or sagging?

And secondly, this straight edge is missing the wood block handles. I've seen a few style's of Brown and Sharpe handle's, but nothing resembling these. This has a flat plate with a stud bellow on either side. The stud's also give place for the straight edge to rest on 3 points when on it's side, but I wonder if you would use eye bolts to hold the handles on? With a straight edge this size, I'm less concerned with hand heat having a major effect on the repeat-ability of the face, but the handles would aid in moving it around and give place for it to rest upside-down.

Thirdly, I'd like to mount an ID plate on it to help reference any certifications. How much distortion could I cause by drilling a pair of 1/8" holes? Normally I'd rivet a tag on, but perhaps screws would introduce less stress?

I'd also be interested in any alternative methods of calibrating these larger straight edges, such as has been discussed in Lurk's thread as well as BrianB's thread on his large cast iron surface plate.
 
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Here's a better shot of the handle boss. There doesn't appear to be any divots from set-screws if the handle clamped to the flat part, so I'm thinking the block had a slot to fit over the flat, and had an eye bolt on either side to hold it in place.

I'm considering going a little further than just a square block and also adding a handle sticking out on each side perpendicular from the casting.
 
MB did you forget what scraping and 1/2 moon flaking looks like? You haven't forgot so soon have you. It looks like a "Chicago Job" to me and not scraped. If I were to loft it I would choke some 3/4" wide Nylon straps around the ribs and use a overhear lift or hoist to save a hernia :-) drilling some small holes for a name plate won't hurt it.
 
MB did you forget what scraping and 1/2 moon flaking looks like? You haven't forgot so soon have you. It looks like a "Chicago Job" to me and not scraped. If I were to loft it I would choke some 3/4" wide Nylon straps around the ribs and use a overhear lift or hoist to save a hernia :-) drilling some small holes for a name plate won't hurt it.

I thought that but the cuts are not deep so I thought maybe they were some kind of hook scrap(?). I'm cleaning it up right now so I'll try to get some better pics of the scraping and measure their depth. It could very well be a cosmetic job. I'm optimistic though as the grime implies it's been on a shop floor more recently than a showroom.

If it needs to be re-scrapped proper, I'm ok. I at least have a machined old-iron blank to start with. But you know I'm gonna bring it to the next Texas class if we have one;). I'll have to check with Steve but I think one of his plates is big enough to check it.
 
In the short term to check this straight edge, WITHOUT an appropriately size reference surface:

My 24" SE is still low PPI but flat, so I can print a few sections to check for local flatness. Once It's closer to 40PPI, I'm thinking I can print in overlaping sections and watch how more-or-less it hinges and prints on the ends.

I have a buddy who's an industrial surveyor (checks oil rigs and pipes for parallelism and the like), I don't think he has or uses an autocoluminator, but he might have something in the laser field that could check flatness. Not sure yet on resolution as I doubt 2 pipes 100 ft. apart COULD be parallel within .0001 or better.
 
J&S Machine in Nowata OK where I will be teaching a class next month just purchased a 4' x 8' Granite for his new shop. I will be checking and touching up a B&S 10' Camel back he bought from me. That bugger is so heavy it has to be picked up buy 4 men and a small boy. I'll check the weight, but it has to be 400 pounds. You are probably closer to Nowata then you are to Navasota aren't you? I stopped once at your plant, if memory serves me write your north of Dallas and near the OK border?
 
J&S Machine in Nowata OK where I will be teaching a class next month just purchased a 4' x 8' Granite for his new shop. I will be checking and touching up a B&S 10' Camel back he bought from me. That bugger is so heavy it has to be picked up buy 4 men and a small boy. I'll check the weight, but it has to be 400 pounds. You are probably closer to Nowata then you are to Navasota aren't you? I stopped once at your plant, if memory serves me write your north of Dallas and near the OK border?

10 feet would be fun! Part of my interest in accumulating a range of straight edges stems from philosophy that my I inherited from my dad in that if you only use a tool once every 10 years, having it is worthwhile. The popular thing these day that if you haven't used something in 6 months, it's worthless and goes to the curb, just doesn't fly with me. As long as I keep things organized and cared for, I think I'm flying under the "hoarder" radar.:crazy:;)

No we're only an hour from Steve's shop. At the 2017 class I drove to Steve's place each day as it was close enough to go home at night. Oklahoma might be too soon for my schedule, unfortunately.
 
I'm looking at a local large surface plate right now that I had previously passed on because it had a lot of damage. I'm reconsidering it though because the price is good and it still has a lot of usable space. It's going to depend on if I can have a granite servicing shop fix it for a decent price and still have it certifiable for Grade A.

I'm banking on using an appropriate size surface plate to blue the straight edge as my end-game way to confirm the flatness of this straight edge.


My understanding of checking flatness is that there are 3 methods that can be used:

1. Comparative - Using another surface that is known to be flat as a master to print or otherwise check the work against (most common scraping method)

2. Generating Flatness - Printing 3 matching unknown surfaces together to "generate" flatness by averaging the errors (long process).

3. Optical - Using light waves or lasers to find the highs, lows, or angles of a surface, such as is used when calibrating surface plates. (requires skill with expensive tools)


As I don't have 3 72" Brown & Sharpe edges, #2 is out the window. But I think using a shorter straight edge and checking for hinge points is kind of a combination of #1 and #2.
 
Or using a precision level say 8" long and with SE flipped upside down slide the level down the SE stopping every 4" and reading the bubble. You can also use a short granite SE or parallel as as wide or a little wider as the SE and say 24 or 36" long to blue up. You can buy a certified SE from Tru-Stone / Starrett in St. Cloud MN.
Another alternative is buy a used CMM / coordinated measuring machine that have precision granite bases and granite bridges that you can make a surface plate from. Used outdated CMM's with old software are cheap as heck.
 
Or using a precision level say 8" long and with SE flipped upside down slide the level down the SE stopping every 4" and reading the bubble. You can also use a short granite SE or parallel as as wide or a little wider as the SE and say 24 or 36" long to blue up. You can buy a certified SE from Tru-Stone / Starrett in St. Cloud MN.
Another alternative is buy a used CMM / coordinated measuring machine that have precision granite bases and granite bridges that you can make a surface plate from. Used outdated CMM's with old software are cheap as heck.

True, using a level would be in a field all it's own own. A precision level is on my shopping list. We have a 4" and 6" starrett that are good for most of our shop uses, but a 12" or 18" one would really be nice to have.

I thought about using one of our VMC's like a CMM with an indicator on the spindle, but the biggest travel we have is 44". I might still do it to see what the results are. I think it would be in the same family of checking the straight edge to a master surface as you are relying on the existing precision of the ways and encoders to read the surface accurately.
 
In the spirit of Lurk's topic working over his larger standards, here's another one for you guys!

With all the eventual scraping jobs I have on the to-do list, I have a number of straight edges on my want list, which include some long ones for checking mill table ways and lathe ways. I know there are ways to do them with shorter standards, but I'm a glutton for punishment;).

SO, I found a 72" Brown and Sharpe at what I thought was a very resonable price, and shipping ended up being an even better deal, so here we go!
View attachment 236370
With packaging, it came in at 93 lbs. My young frame can move it around with little trouble, but holding it at a 45 to print a lathe's V-way will likely be difficult, so I plan on making a portable hoist that I can support it with.

It's pretty grimy but the face is in decent shape. I don't see any wear, damage, or excessive corrosion, and it looks like the most recent scraping was professionally done. I plan on eventually getting a larger granite plate at our shop which I'll be able to use to calibrate this, so in the mean time I'm going to give it a light stoning and trust that the surface is usable. While I'm cleaning it up, I plan to give it a new coat of paint too. I'm thinking grey with black lettering would do it well.
View attachment 236376
View attachment 236377
View attachment 236378

A few questions for you guys:

I plan on making a cart to store and transport my larger straight edges. I'm thinking a flat bottom cart long enough for an 96" straight edge (still on the want list), and 12" wide. I'd like to store them face down to protect them, but as the cart won't exactly be a flat surface (relatively), If I support the straight edges at 1/3 in from the ends, will that negate the possibility of them twisting or sagging?

And secondly, this straight edge is missing the wood block handles. I've seen a few style's of Brown and Sharpe handle's, but nothing resembling these. This has a flat plate with a stud bellow on either side. The stud's also give place for the straight edge to rest on 3 points when on it's side, but I wonder if you would use eye bolts to hold the handles on? With a straight edge this size, I'm less concerned with hand heat having a major effect on the repeat-ability of the face, but the handles would aid in moving it around and give place for it to rest upside-down.

Thirdly, I'd like to mount an ID plate on it to help reference any certifications. How much distortion could I cause by drilling a pair of 1/8" holes? Normally I'd rivet a tag on, but perhaps screws would introduce less stress?

I'd also be interested in any alternative methods of calibrating these larger straight edges, such as has been discussed in Lurk's thread as well as BrianB's thread on his large cast iron surface plate.

That flaking makes no sense. At Tuckahoe Nathaniel had a 5 foot B&S SE it had very deep scrape marks, but no flaking.


dee
;-D
 
Funny how things work. I went by a local antique/junk shop on my lunch break today on unrelated business, and while I was there I noticed they had a 12" Starrett precision level on the wall! Somebody had polished all the paint off and the base is fairly pitted, but I suckered myself into buying it. Got it back to our shop, stoned the bottom, and checked it on our surface plate and It seems to be accurate. It would be an easy job to regrind the base and get it re-calibrated.

It's one of the ones with .005" per Foot increments on the vial (which I verified with some shim stock), so not a master level, but between it and our other 2 smaller ones, I'm going to see how close the straight edge is tonight.
 
Funny how things work. I went by a local antique/junk shop on my lunch break today on unrelated business, and while I was there I noticed they had a 12" Starrett precision level on the wall! Somebody had polished all the paint off and the base is fairly pitted, but I suckered myself into buying it. Got it back to our shop, stoned the bottom, and checked it on our surface plate and It seems to be accurate. It would be an easy job to regrind the base and get it re-calibrated.

It's one of the ones with .005" per Foot increments on the vial (which I verified with some shim stock), so not a master level, but between it and our other 2 smaller ones, I'm going to see how close the straight edge is tonight.

you can scrape it :)

https://www.practicalmachinist.com/...aster-level-342871/?highlight=precision+level

dee
;-D
 

I'm half-way there! I decided to spend a couple hours on the level before I took it home tonight. I already surface ground the bottom through about 90% of the pitting (used the existing surface as my reference by averaging the 4 corners height), polished the edges and vial tube, and the casting is in rattle-canned black and drying in our heat-lamp cabinet. I'll finish scraping the bottom face tonight.

Between the polishing and the heat lamps, I didn't expect the bubbles to shrink (though it makes sense). I had an "Oh crap" moment when I watched a little 1/16" diameter bubble float across the main vial.
 
I can give you a deal on a .0003"/12 bubble that you can replace you .005" bubble with if you want. Those bubbles are set in plaster of Paris with a white piece of paper under it. It is impossible to remove the old glass with out breaking it, so you could do an old machinist trick and pull off the old vial and set the new one on top of clay to cradle it. Or machine a new tube or buy a complete one. Or borrow a level from Steve. Or take you SE down to Steve's and use his new to him AA plate.
 
Well I haven't scraped the bottom of the 12" level yet, but it's in much better shape now that it's ground, cleaned, and painted. I calibrated it and our two smaller levels doing the 180 flip method. The 6" is actually an old Starrett #97, the one's with a plain glass vial and no graduations, while the 4" and 12" are both the .005 increment ground-glass vials.
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I'm probably going to keep the 12" as a .005" unit for use in our Inspection area and keep looking for an actual Master level to use for machine reconditioning and commissioning.

I also have the wood blocks in place. The handles I want to add are yet to come, but I have their mounting holes in place. The eye-bolt tie downs worked nicely pulling the blocks firmly into their corners and will also serve to pass through and pull the handles into their holes.
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I wanted to make them out of hardwood, but settled for pine 4x4's as they fit perfectly. That exquisite finish is the result of giving them a quick bath in the cutting oil sump under the Kearney Trecker :D.
 
Here's my current assesment of the 72" Brown & Sharpe, using the Starrett #98 12" level:

I picked a clean patch of floor for the SE to lay on it's back and shimmed it up until it was resonably level. I then marked it off in 6" increments. Working left to right, I checked it with the level in 6" increments and found that the left side was about .003" (splitting divisions with the naked eye) lower than the right, but it had a gradual slop, no concave or convex arc. So within the .005" resolution, I'm flat! Now with a better level, that might not be the case, but it's deinently close enough to scrap.

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Next, I checked it with my 24" straight edge:

Now the 24" isn't finished yet. I've printed it to around 15PPI using an un-certified un-graded surface plate and am waiting for it to be certified before I continue to 40PPI. But it has full coverage and hinges well so I figure it's enough to play with for now.
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Similar to the level, I worked my way from one side to the other checking hinge points and printing as I went. The middle right partially hinged properly, but the rest all hinged close to or on the ends of the 24" SE. Beings as it's the heavier Dovetail SE, I'm getting the impression that it's weight is making the 72" SE sag, or it does have some bow to it that's less than the level would pick-up.
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The print wasn't terrible, but I think it confirms Richard's suspicion. It's a "pretty face," but there are low spots. Looking closely at the scrap marks, you can kind of see two levels to it, the bottom layer looks like a worn rusted way that still has visible scraping, while the top layer is the light flaking job.

It's fixable! But I don't think it's going to be usable until then.
 








 
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