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Shortening a straight edge

Hobby Shop

Stainless
Joined
Mar 20, 2014
Location
Michigan
Hey guy,

I bought a 12’ straight edge and need some advice on how to cut it up in to more manageable pieces because the damn thing probably weighs 1200lbs.

In the end, it would be nice to have a square to check spindle to knee perpendicularity and to have an edge about 6ft-7ft long. I already have a 3ft straight edge and Biax.

I’ve been collecting some tools because eventually……Far far off into the future, I would like to scrape my K&T 3CH, 54” P&W and touch up my 54” Pacemaker.

I’m in no hurry to cut this thing up and open to trades for a 6-7’ straight edge and a decent triangle square.

Thanks,
Andy
 

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I am not sure that you will end up with something usable, if you cut it, since you are going to sever the camelback stiffening member. Plus, you would have a 6-7 ft straightedge that is much heavier than anything else available.
I think that you would be much better off trying to barter this monster for something more usable for you. Although not many people would need it, there is some market for a 12 ft straightedge in decent conditions. Your chopped chunks would be worth scrap price.

Paolo
 
Thanks guys. This is exactly what I needed to hear. I don’t wanna do anything to ruin it if somebody out there can use it.

I’ll spray it down with some rust inhibitor and put it in a barn off the ground. If anyone knows of a rebuilder needing this thing, point them in my direction. I’d prefer trading even up for a nice 6-7’.

Andy
 
You know, if I were going to put it out in the barn (that presumably has a good roof) and expect it to weather a few years out there until someone shows up who wants the SE, I think I'd just paint the raw surfaces of the SE with whatever shaker can was on the shelf. Latex house paint would do the trick just fine as well. The paint would be very easy to remove when the time comes and would be absolutely reliable in terms of rust prevention. The various proprietary anti-rust liquid formulations work OK, especially in terms of weeks or months. But, realistically, this is more like a long term storage. When "that guy" comes along and is so happy to find the long straight edge he's been searching for, he'll be even happier that the precision surfaces are rust-free.

Denis
 
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I'd like to trade for a 48" as I don't have a 60". But the shipping costs would break the bank from MI.

Richard, let me ask this. How long can a 48” scrape flat? I’d imagine not more than a foot in either direction so about 6ft?

My intention is to eventually scrap in my 54” lathe and the bed is about 7ft long.
 
If you're planning any trips this spring you may find somebody willing to meet you along the way to make a swap.

Just a thought....
 
You would have to step scrape using it. Scrape the lowest 50"s. You don't rub the entire lathe bed. Only the most worn area rubbing 1" longer on each end. After you have that area scraped you partially move mout and scrape the next 24" until that area is finished. It could be each end but not knowing where it's worn im generalizing.
 
I don't NEED a 12' SE, but wouldn't mind having one for the self-abusive fun of scraping and using one, and "someday" if/when I get to scraping the bed on my plainer. I have an extra 6' to trade but transport would be the kicker as I'm not traveling that way in the foreseeable future. If Richard or someone else doesn't take it... keep us posted.

Out of curiosity does it have any makers marks on it?

One potential use for one of these I think would be for testing other straight edges, as nothing's going to be too long for it, lol. The trick would be the initial qualification of knowing THIS one is flat. I had started a thread a couple years back on trying out other methods to prove the flatness of a big SE and how they compare to properly printing on a surface plate, but haven't circled back to that project yet.

Big Straight Edge Tests
 
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@Hobby Shop
I plan to go to Rich this year to scrape. I'm in Ohio just East of Sandusky.

 
As NB Nagle said ..
But also endless amateurs make flats, spheres, and mirrors, for telescopes, for not much money and to accuracies better than 0.1 micron, relative.

My "feel" or guesstimate is that a CI straightedge of large length would probably twist in x - the measurement plane, possibly warp - like an airplane propeller, and possibly twist also in the y axis, aka sideways, when cut in half.

I also "guesstimate" the errors might be minor, but perhaps not.
There may or may not be stresses in the structure, that would warp the thing on cutting it
My "feel" is that there will be significant twisting. Fwiw..

It is quite difficult to make a long flat of 1 micron straightness without excessive weight.
Moore proved it and his company did a lot of work on this.
 
I just wonder how do you rub such a heavy SE with anything if you need a crane to hoist it.
 
Richard,
I responded to your PM with my phone number and email.
I don't NEED a 12' SE, but wouldn't mind having one for the self-abusive fun of scraping and using one, and "someday" if/when I get to scraping the bed on my plainer. I have an extra 6' to trade but transport would be the kicker as I'm not traveling that way in the foreseeable future. If Richard or someone else doesn't take it... keep us posted.

Out of curiosity does it have any makers marks on it?

One potential use for one of these I think would be for testing other straight edges, as nothing's going to be too long for it, lol. The trick would be the initial qualification of knowing THIS one is flat. I had started a thread a couple years back on trying out other methods to prove the flatness of a big SE and how they compare to properly printing on a surface plate, but haven't circled back to that project yet.

Big Straight Edge Tests
I thought I posted a picture of the tag. It’s made by Challenge.

Andy
 

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I just wonder how do you rub such a heavy SE with anything if you need a crane to hoist it.
I've done a little with my 4' and 6' SE's. It's more laborious, but it makes you to keep an eye on how they hinge or rock on the surface being printed, which you're supposed to do with all SE's anyway. I have a little rolling jib crane with a rope block-n-tackle for stuff like this, but it wouldn't be near enough for that 12'. I think a gantry hoist and chain-fall would be in order at minimum.
 








 
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