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View Full Version : Accurate Aluminum Straightedges???



lklb
03-05-2005, 05:40 PM
As I Rumaged through Ebay I came across this HUGE straightedge-- http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=3878928007&ssPageName=STRK:MEWA:IT
I was always under the impression that aluminum was a poor choice for straightedges -So I went to the Busch precision web site and down loaded their catalog-- http://www.buschprecision.com/tooling.htm all sorts of Aluminum \CI clad-
I am sure VERY expensive!! Straightedges And large master Squares --All ground or hand scraped to a couple of tenths.
I was considering buying a couple of used cast iron straight edges 4' or so , but the market interest seem to be so strong and supply so small that prices are quickly going thru the roof!!
Question - Does anybody know if an acceptably accurate (1/2 thou. or better)straightedge/ scraping reference
could be constructed of old 4 foot aluminum levels perhaps bonded like the busch examples ?

Im told Normalizing aluminum requires 400-500 degrees followed with a bath in liquid nitrogen. Hell the Pizza guy down the street could fit a 6 footer in their oven on a slow night!

If this could work I could envision end fixtures screwed in to hold a full lengthed insulated handle, even a taut wire cantenary sag compensator of some sort..
built in threes they could be self checking.
Any way they would be dirt cheap and avoid the problem of gambling on a $1000+ investment of several old large and untested scrapers straightedges.
But maybe Im crazy.

precisionworks
03-05-2005, 06:53 PM
It's tough to find something like you want on eBay. I looked for six months before giving up and buying a 48" Starrett from J&L Industrial. They have "web sales" two or three times EVERY month, 25% off. So that 385 Starrett Bevel Edge that lists for $230 costs $172 on sale. Brand new. No nicks, no dings, no rust. For me it was worth it, though it hurt at the time!

Specifications:
• Edge straightness .0002" per foot
• Parallelism .0004" per foot
• Precision made of fine tool steel to rigid Starrett standards
• Completely ground throughout and finely finished
• Unexcelled for drawing or scribing straight lines and checking surfaces for straightness



[This message has been edited by precisionworks (edited 03-05-2005).]

matador
03-05-2005, 10:26 PM
i have a 4'aluminium(chicom) rule that i use as a straightedge for woodwork,but i wouldn't rely on it being accurate enough for what you want.
If you really need that accuracy,there's no other way.layout the dollars and console yourself with the thought that money spent on good tools is never wasted.

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Hans

Excitable Boy
03-06-2005, 05:52 AM
I guess I did better than I thought on my straight edge. I got a Starrett 385, but it is only 32" and is marked a Special on the box. It was like new in box and looked like it was rarely if ever used. It came out of a RAtheon plant that had closed. I think I gave the used machine dealer I bought it from around $20.00 for it!

John

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Pursue Excellence and the rest will follow.

beckley23
03-06-2005, 10:35 AM
If you are looking for a scrapers straight edge, this is what you are looking for;
http://cgi.aol.ebay.com/ws/eBayISAPI.dll?ViewItem&category=12581&item=3879179916&rd=1&ssPageName=WDVW
The price is pretty good now, but I would expect it to go up. This seller also has a smaller up for auction.
You will need to check the flatness against a surface plate.
Harry

Evan
03-06-2005, 11:47 AM
The question guys is, can a few cheap aluminum levels be turned into reliable straight edges? If they are scraped together in the usual fashion how accurate may they be expected to be? I know that the the expansion with temperature will be greater than iron so that will mandate using gloves or insulated handles as well as the easier chance of damage, but: Can they be as accurate or at least nearly as accurate as an iron edge? (I say yes)

Why didn't I think of this? As most of you know, I am a fan of aluminium.

lklb
03-06-2005, 12:59 PM
Harry-
yes, I saw those straightedges and I have access to a large 6 or7 ft flat to verify.But I would guess that large used straightedges are approaching $100/ft on Ebay with no guarantee of condition as sent or shipping damage .New these are what? $200/ft? Too rich for my budget right now.
My granfather and my uncle were both machine tool rebuilders. When they passed on I inherited an amazing collection of tools -B+s and other straightedges to 8 feet long ,load of parallels and large squares,cast iron surface plates with crane,british master precision levels,precision water levels, taut wire rigs w/readers,optical tooling+ telescopes,powerscrapers and a lot of other stuff. My job took me out of state for 2 months, when I got back all I left was 4 anderson scraper handles ,2 boxes of scraper blades (not even carbide!)and a couple of small CI surface plates. Sucks to be me. But that was a long time ago. Saddens me to think I can never replace that stuff.

I guess i will have to fab my own stuff and just check them a lot against surface plates. thanks LK

beckley23
03-06-2005, 05:18 PM
LK- I bought a 4' straight edge on ebay a couple years ago for 250.00. It's an auction you never know, set your top price and don't go over it. If you get it, make sure the seller packs in a well padded wood box that is well built. UPS isn't too gentle.
Harry