Please suggest on a camelback straight edge

I'm torn between buying an "old American iron" straight edge or a brand-new "JASH" one.

If I get it right, JASH is an Indian company. I have a few other calibration tools from India and they all give the declared accuracy with no problems. On the other hand I'm trying to buy American-made whenever possible. The American straight edge is also little longer - 35" versus 31", but even 31" is sufficient for what I'm going to do.

I need a straight edge mainly for scraping and machinery repair - I have a home shop with an old mill and, potentially, an old lathe.

Price-wise, including delivery, they are both ~$400.

Links on eBay:
Jash 31" Cast Iron ( Bow / Camel Back Type ) Straight Edge | eBay
Camelback Straight Edge 35 3/4" Lower Length x 2 Inch Machinery Leveling | eBay

Thanks!

I suppose this is unfair to Jash as I've not used their stuff, but my (fortunately) limited experience with tools from India is dismal. If it was me, it would be a debate maybe if the American one was $400 and the Indian one $20.

End of the day, you really have to trust the tool or be able to check it. Scraping is just too much bloody work to get it all wrong because the straightedge was a banana, no matter how much you save.

I've got no axe to grind on any nation's straight edges, but I don't regard cast iron camel back straight edges as reference instruments. Check it against your surface table and re-scrape as needed, whoever it comes from.

Mark Rand has the right idea: trust but verify.

Even if a straightedge left the maker in perfect condition, it could have been abused during storage or shipping. A simple check on a trusted surface plate is always called for when you receive a "new" straightedge.

So, what you guys are saying is: even a "new" straight edge needs to be checked and re-scraped, so there is no benefit in buying it rather than buying a used straight edge of unknown accuracy?

How doo you check it on a surface plate?


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Ox

Ox said:

How doo you check it on a surface plate?

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Same way you'd check a part for flatness. Goop up the surface plate with marking compound, apply the straightedge to the plate (using proper technique), notice if it's convex (or has a raised ding) from touch/feel during the application, and read the marking compound transferred to the straightedge.

Frigzy said:

So, what you guys are saying is: even a "new" straight edge needs to be checked and re-scraped, so there is no benefit in buying it rather than buying a used straight edge of unknown accuracy?

Click to expand...

no, a new straight edge shouldn't need to be scraped. Ideally any one should be checked, but we don't always live in an ideal world; i.e. have a plate large enough and within calibration to a sufficient tolerance. When that happens, it comes down to a probability and trust, you make a judgement call. I've a 60 inch US made one with little visible wear bought from a member here who knows what they are doing when in comes to scraping. I trust it for those 3 reasons - quality make, little wear and knowledgeable/credible seller. I trust it a heck of lot more than I would a new one from India.

Its like if bought a 10" mic brand new with no way to check it. i'd trust the new Mitutoyo from a licensed distributor a lot more than the lucky yuk foo one from China. The Mitutoyo could be bad, and the yuk foo could be perfect, but with no way to check the probabilities are in favour of the Mit.

For smaller reference flats, I've got references to check and they proved to be perfect, I don't have a way to check the 5' one.

I doubt a commercial guy would or should trust the mic or camelback without checking it. I wouldn't as being wrong about trusting it could be expensive, both in time and reputation. But for my work in my home shop, if their are solid reasons for there being a high probability of it being good, and it would be very difficult/expensive to certify that, well hey, the tool gets used. If you judged well, 99.9% of the time it goes smoothly which is probably ok for work for yourself.

Let's analyze the actual situation: on one side a new straightedge of more or less unknown quality (although you can search the "Machinery Reconditioning and Scraping" forum, more in tune with this kind of problems, and find some feedback for that maker), and an allegedly American made one of unknown maker and quality.
Personally, I would go for the lightest one fitting my needs, assuming that each of them must be tested against a trustworthy reference each time prior to using them.
If the straightedge is significantly longer of what you want to spot you will risk of having an erroneous spotting, due to the weight of the overhanging part of the instrument (unless you're extremely careful and apply a few tricks, you'll end up scraping convex) and, in many cases, you won't be able to use it due to interference with other parts of the machine casting.
Weight wears you out pretty fast and detract significantly from the feeling necessary to assess the distribution of true bearing points during the spotting operation.

My 2 cents.

Paolo

Thank you guys for all the information. Somehow, I ended up buying a 39" JASH

My justification was simple: I measured length of the ways on my Abene VHF-3. Vertical ones are 36", diagonal ones (where the headstock slides) are 34" and table is 47". I'm also going to get a lathe which is at least 14x40 (which means, bed is longer than 40", probably closer to 50"). And the last, I have no idea about scraping at this point, there is a high chance of screwing up the things, so it would be nice to exclude the straight edge from the equation (JASH promises 0.0002” of accuracy right out of the factory).

And, if I still find it to be too long, I can just cut it onto 2 pieces - 20" and 18" - how cool is that!

Here is a link Jash 39" Cast Iron ( Bow / Camel Back Type ) Straight Edge | eBay

Seller accepted $300 offer (which is $411 with delivery for me).

I will post an update once it arrives.

Thanks!

Frigzy said:

So, what you guys are saying is: even a "new" straight edge needs to be checked and re-scraped, so there is no benefit in buying it rather than buying a used straight edge of unknown accuracy?

Click to expand...

Pretty much. Old is good for stability. Stresses may have had 80 or a 100 years to release, SE been rescraped many times already.

Look for OLD B&S Camelbacks. They are "good enough", but lighter than most of the modern ones.

Best of deals is if the person selling IS a scraper. Two levels, two SE here were all scraped for me as part of the purchase deal from PM members. One made a video of his work.

Lots of folk only needed an SE for a coupla projects, and had to scrape them-in before they started their own work. A light once-over before shipping isn't terribly costly.

"Unknown accuracy?" All I need is useful. Not miraculous. The four mentioned from PM members range from more than good enough to downright gorgeous.

I've been on a bit of binge working on and using straight edges the last two years. This is not my day job so take the following comments with that in mind. A straight edge is a tool, not a reference. It takes the reference surface plate's flatness to your job. SE's move over time. A lot. Whether from heat carelessly applied by hot hands, or sun hitting them, careless storage, etc. SE's also warp and move over time as internal stress gets relieved even if cast with good metalurgy, foundry practice, and careful machining, and scraping. Nature of the beast. I don't care what country any of my tools come from, it's results I want. And to get good results you can expect good SE's to need re-scraping from time to time. Remember, the reference is the surface plate (which also needs checking and re-doing, but that's another subject), not the straight edge. And yes, I know some folks consider a SE nothing but an elongated surface plate but that's not how they are used. So to me, the most important part in the whole scraping process is not a straight edge but the surface plate's quality and maintanence and keeping it at roughly 68deg F. From the surface plate a good straight edge can be maintained...

Lucky7