Arch bridge straight edges

[Martin]

Hello group,
Today, I stopped by a local casting company. I spoke with the guy about casting some arch type straight edges. He gave me some options as to the type of pattern material to use. I can use wood or styrofoam. I was thinking about three different sizes. 1, 2, and 3 foot lengths. But regardless of the length, the cost per piece would be about the same, $150 each. There use to be a guy who traveled around here that did stress relieving. I don't know what that will cost. But I will see if I can locate a stress reliving service for the castings. And if you have "the reconditioning book" and have started looking for the tools, you will recognize that this is not a bad price for a straight edge and it will make a great "first project". The pieces will only be cast, stress relieved (if possible) and then shipped. They will have a 45 deg. cast along one edge. I will not do any machining to them.
If this sounds like something you would like to do. Let me know.
Martin

[This message has been edited by Martin (edited 12-04-2002).]

[Forrest Addy]

They do look like bridge trusses, dont they?

The common terms is "camelback" because of the hump shape. Maybe you and Ken should join forces.

As for lengths a 1 footer can be machined from a "L" shaped chunk of cast iron. A straight edge that short won't benefit much from a light weight design as even a solid design will weigh only a few pounds.

I once used a 20" (1/2 meter more likely) fitter's flat that was a superb compromise zmong size, rigidity and weight. I wish I'd drawn a sketch. It was German made before WW II and owned by an old toolmaker who was an unreconstructed Nazi. I'll think about it.

A 3 ft straight edge might be heavy enough to require a crane. I used a 32" Challenger straight edge that must have weighed 70 lb. Maybe it's proprotions and members could be reduced. There was a lot of iron there.

Speaking for myself, I'd go for a straight edge maybe 18" to 20" and a light weight 36" to 42".

[hms50]

Good Morning, I read your post with interest and like your proposed projects. As I also wanted to learn how to scrape and make some edges, I'm offering the following unasked for comments/advice. Again, I don't know much, but, A friend of mine is a machine rebuilder and master scraper. I am amazed at what he can do and what he knows. He makes his own scrapers, straight edges and special gages. He originaly intended to market these and write a book on scraping and building tools, scraping furniture ect. I took hundreds of photos of him working and all the incredable things he made for his work. Unfortunately, it ain't gonna happen. He now spends most of his time working on his own pet projects. I asked him if I could publish his bussiness name on this board, you would love his prices and the quality of his tools, but he said no. He has told me some of the things he discovered about making the type of straight edges you want to have cast. Not all foundrys could make the castings come out right. Often, the rough castings had hard spots or inclusions in them. Somtimes the iron just didn't machine or scrape clean. He finaly found a foundry in Rhode Island that could produce excellant results. The stress reliving is very important. If this is not done, there is an excellant chance that the edge will warp some time after you have it all scraped! The good news is that stress reliving is a simple process and less expensive than say heat treating a block of 01. The trick,(as always) is to find a heat-treat shop that has done it and knows how. He uses a planer,(14' bed!) for the machining and claims that the single point tool causes less stress build-up than milling would. He rough machines the castings and leaves them for a year before scraping. After the first scraping, (which I would consider to be excellant), he again ages the piece, and re-spots and scraps again. I was lucky because he sold me some of the machined castings and did his best to teach me how to scrape them in. He did the final scraping because I could not for the life of me "read" the spots well enough. The 18" edge was cast 5 years ago and the foundry and sress reliveing cost about $65. He spent a lot of time on the patterns, they are not just simple, solid sections. The "camel's hump", has a series of hollows in it which make the edge lighter and less prone to warping, both over time and from the heat of one's hands. I think it is a great idea for you to have some cast and scrape them in. Although I could never get them as accurate as he does, they would be good enough for most things. If I was looking for a foundry, I'd like to find one that had done edges before.
Best of luck!
hms50

[Forrest Addy]

Hm. I wonder it the above referenced "master scraper" is our rare and elusive friend Micheal Morgan who promised so much and delivered so little too late.

I think there are still people who having paid him good money are still waiting for straight edge castings and books.

If so, I wish he'd shut down his website so others won't get euchered.

[This message has been edited by Forrest Addy (edited 12-06-2002).]

[Thrud]

Forrest
You know human nature better than that. Lots of people are interested in the subject so they dangle carrots before thier noses and the lemmings plunge over the cliff.

Best defense with these clowns is to use Visa or Mastercard - they are not allowed to charge your card until the product is shipped. This is part of the merchants agreement that they have to sign to accept payment by these means. At least with these cards you have recourse less annoying than small claims court. Buyer beware!

With all the equipment that is sold on eBay at rediculous prices it makes more sense to purchase a finished camelback straight edge or even granite ones. I prefer granite straight edges - easier to care for/cheaper.

[Martin]

It's sort of strange that someone mentioned the $65.00 straight edge in the above message.
I almost went and ordered one of those, but "something" kept me looking elsewhere. And having not found something adequate, I decided to look into having my own cast.
And now Thurd mentions granite straight edges and that sounds best of all.
Having looked through all of my catelogs, I have not seen a granite straight edge mentioned. I have found granite surface plates, but no straight edges.
Thurd, could you list a source for the granite straight edges.
Thanks

[crossthreaded]

I got my granite surface plate from Mohave Granite years ago. They were reasonable for the time & included the a welded steel table. The slab weighs 400 lbs. They were a tombstone company that branched out into surface plates. I would image any tombstone company could supply the rough straight edge.

[Spin Doctor]

If your looking for a commercial granite staightedge hold on to your shorts and try LS Starrett. The streets of Athol Mass really are paved with gold

[hms50]

Nope! The master scraper I refer to would'nt even know how to turn a computer on, and is as honest a man as I have ever known. I mentioned the $65 because I thought it was an indication of what one would pay the foundry and heat treat shop.
best of luck,
hms50