# Curiosity about straight edges and metal



## Purrmaster (Sep 1, 2012)

This post is largely just for the sake curiosity.

I know very little about metal working or the manufacturing of metal items. But I bet some folks on Lumberjocks do.

I've been looking at getting a better straight edge (or straightedge, I don't know which is correct) to help me check the alignment of my bandsaw wheels and for other machine set up. I'm probably going to snag one of the Lee Valley steel straightedges.

While shopping for straightedges I've noticed that the aluminum version are cheaper and often thicker than their steel counterparts.

I'm curious as to why this is. I *think* (feel free to correct me if I'm wrong) that aluminum is a more expensive metal than steel. *If* this is so, why do aluminum straight edges cost less than steel ones?

My hypothesis is that the cost difference is due to the labor required to manufacture a steel straight edge versus an aluminum one. Aluminum is softer than steel and easier to machine. So it may be faster and simpler to machine aluminum to the required specifications.

I also believe that aluminum parts are often manufactured by "extrusion." Perhaps an accurate aluminum straight edge can simply be extruded and doesn't even need to be machined.

So…. does anyone know the answer? Am I totally off base?

Thank you for satiating my curiosity.


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## shampeon (Jun 3, 2012)

Straight edge punks don't drink, do drugs, have sex, or (usually) eat meat. They're known for the black Xes they put on the top of their hands (originally the mark that you're under 21 at an all-ages show and can't legally buy alcohol).

Metal is typically played at a slower tempo than punk and features more solos. Metal evolved out of blues and hard rock, while punk was a stripped-down, back-to-basics response to much of the music being made in the mid 1970s.

Oh wait….

You're correct that aluminum extrusions are much less expensive to produce than machined steel. The cost of the material is pretty low for both, although good steel rulers are alloyed to keep them brighter and more corrosion-resistant.

A lot of it is consumer expectations, too. A high-quality machined aluminum rule can certainly be made, but most people expect steel at the price point it would need to be at.


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## Purrmaster (Sep 1, 2012)

So are aluminum straight edges typically just extruded or are they also machined after extrusion?


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## Ocelot (Mar 6, 2011)

While alluminum is more expensive per pound, it takes less pounds of it to make a straightedge. I think you are right, however that the cost difference has more to do with manufacturing cost than material cost. I have an alluminum straight edge, and am perfectly happy with it. I think it was extruded and then machined.

It's good enough for me - and way better than the edge of a foam-plastic yardstick from a fabric store, LOL.


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## realcowtown_eric (Feb 4, 2013)

There are straight edges and there are straight edges.

Right off, first quality straight edges are expensive new, perhaps less so in the flooring world than in the machinists world.

Thus, used is an economical option to explore, but like squares, they may have been abused. Run a carbide laminate scoring knife along them, and the straightness can disappear, so you have to be vigilant.

And like carpenters squares, where some of them have copper to help minimize the efffect of localized heating (one part in sun, other in shade) which would distort them, when you get into machinists straight edges, localized heating (like from your hands) can distort them. My long ones have little notes on them…"support here"--not "hold here"

I daresay Aluminium straight edges are firstly more susceptible to distortion from localized heating, and will be even more affected by carbide scrapers or even an olfa knife nick or two. Also, as the aluminium products are typically of the flooring installer armamentarium, they would originally be of lesser precision that the steel machinists would need.

All that being said, an aluminium straight edge of good condition, and without dips and dives in it would likely suffice in the wood-butchers shop. A light jointing with a file will remove any tool box nicks and burrs.

A good drafting equipment supplier can provide straight edges maybe up to 3', but they are thin and flexible;
Flooring supplies shop (where the tradesment buy their tools, not the local flooring store) will have the aluminium straight edges. Suppliers such as Gundlach and Roberts are probably on line

indeed they are
http://www.tileprotection.com/Aluminum-Straight-Edge-Set-Gundlach-No.-20.html 
from the flooring world

or
http://www.amazon.com/Starrett-380-72-Straight-Length-Thickness/dp/B0006J4H4K
from the machinists world.

Hope this adds a tad of perspective

Eric in Calgary
search and you will find!


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## woodchuckerNJ (Dec 4, 2013)

Get yourself a long level. And use it to get the wheels coplanar, it will come in handy for other things.
I used a 48" level.

BTW you are not looking for .001 in alignment, even 1/64 is pretty good.


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## Sigung (Nov 20, 2013)

Again I find that our paths are similar. I struggled with the straight edge question until I started adding up the cost of inaccuracy in my shop. If you cut a piece of wood on four edges, 1/64" out becomes 1/8" out. Can you tolerate that? Depends on if you are building a house or a box. It's not so bad on a large scale, but on a small scale things just don't work if inaccuracies are more than .005. If you spend a bunch of money on a piece of lumber and you ruin your project because of inaccuracies, you will waste the cost of a good straight edge many times over. I've learned that accuracy, while seemingly expensive at first, is the most cost effective investment you will make. It's fine to source out cheap wood, but with accurate tools, such as a good straight edge, you can turn firewood into a masterpiece.


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## bowedcurly (Aug 31, 2013)

you can get phenolic straight edge on ebay 48" for like 54.00 1/2 inch thick, glass cutters use this style of edge peachtree woodworking also has phenolic edges for sale


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## Purrmaster (Sep 1, 2012)

Phenolic straight edge? Interesting. I didn't know they existed.

The main reason I'm going for the steel straight edge is that I want something tough. With my aluminum ones I've noticed that if they get knocked around even a little bit they tend to bend. Not much, but enough to make me question their accuracy. The steel should be more resistant to "de straightifying". I'm careful with my straightedges but things do fall.

I'm a little surprised there isn't a ceramic straightedge. That would keep its shape well. Granted, it might shatter if you drop it on a hard surface. Might be a good trade off though.


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## TheWoodenOyster (Feb 6, 2013)

As far as your original question, I think the guys above have it pretty correct. My guess is that the aluminum ones are extruded and then machined a bit, and as stated above and as you surmised, it is easier to machine aluminum than steel. That probably explains some of the cost difference.

I got really into the straightedge thing a few months ago but put it on the backburner. No doubt an accurate 4' straightedge is a great tool to have for things like alignment, checking edges, and jointer setup (AAAAAHHHHHH!!!!!). I have found that for the time being, a good quality 4' level is still quite acceptable for me(I would guess mine is within .005 or so over the 4').

A straightedge might be one of those things that you think you really need until you forget about it for a week. For me, I have found that money could go toward more useful tools at this time, but that might not be the case for you. Either way, a 4' level should do for most applications, but if you feel you need one by all means go for it.


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## ScottC (Apr 6, 2010)

Shampeon, that was pretty funny.


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## Finn (May 26, 2010)

I never thought of using my level as a straight edge. Good idea. I am a retired sheet metal worker so I still have steel straight edges 4' and 3' that can be bent to a nice curve but will not kink. I have had them for over forty five years now. Useful and still straight. I got mine from sheet metal wholesaler in Milwaukee.


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## MrRon (Jul 9, 2009)

A steel straightedge is sturdier than an aluminum one and will hold up better if abused. Take care of it and either one will serve you.


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## MatthewG (Oct 16, 2010)

Aluminum and steel both have advantages-consider that both aluminum and steel framing squares are readily available, which means they both have their advantages. Some of the advantages are obvious. Aluminum is lighter, easier to machine and extrude, can be anodized. Steel is much harder, certainly cheaper for mass produced objects, and heavier (which may be useful at times.)

My personal experience with straightedge and squares depends on size. For larger or longer things (a framing square of bigger) I think aluminum survives a drop better, and I like the lightness of it. That said, steel generally has tighter tolerances, so if that matters, steel might be the way to go. Almost all of the smaller squares are steel.

I have 3', 4', and 6' aluminum straightedges-really, they are just the $10 inexpensive type that you can get about anywhere. If I bend or bang it up or nick one badly, I just replace it. That said, when I pick one, I check bring something I know is straight with me to make sure I get an accurate one, just like you check a level before taking it home


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## shampeon (Jun 3, 2012)

Scott: glad someone got my joke. 8^)


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## realcowtown_eric (Feb 4, 2013)

Levels I too use in a pinch, but I know I don't have one of the ones that -was it a satanley- was specifically made with concave edges so it only touched at the ends. That would not work well with as a straight edge….

Eric


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## Whiskers (Nov 6, 2012)

For machine setup, I picked up a couple of the aluminum straight edges from Peachtree woodworking out of Atlanta. I'm pretty sure they the same thing that Lee Valley sells as they were the same price, and look identical. They do sell a lot of the same merchandise. Only reason I ordered from PTree over Lee Valley is they are cheaper shipping and Atlanta is only 1 shipping day away from me, where LV is a week and more expensive. They have served me well, and I also use them in the shop for drawing straight lines etc when I need to. One is about 3' long, and the other is about a foot.


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## NiteWalker (May 7, 2011)

I have 24" and 38" veritas aluminum straightedges from lee valley and they're plenty accurate for setting up woodworking machines and for general shop use. They have convenient holes for hanging, which I do, to prevent being stored haphazardly.

Sure, a steel straightegde would be nice, but the aluminum ones are fine too.

I just saw the peach tree aluminum straightedges; they do in fact look like the veritas ones (but without the ridges), but the product info makes no mention of accuracy over their lengths. FWIW, the veritas straightedges are accurate to within .003 over their lengths.


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## bowedcurly (Aug 31, 2013)

I have the CRL phenolic straightedge it is a very good stable straightedge, they use them in glass cutting but it works great for my applications and it's very tough I have some large rare earth magnets rigged on it, and it's spot on


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## MrRon (Jul 9, 2009)

I have a 60" Starrett steel straightedge. New they cost several hundred dollars, but I found this at an unclaimed storage facility for $15. I was just in the right place at the right time. That thing is HEAVY; weight around 20#.


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## NiteWalker (May 7, 2011)

Killer score Ron.


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## Purrmaster (Sep 1, 2012)

I looked at some the Starrett straight edges and they cost as much as my bandsaw.


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## bowedcurly (Aug 31, 2013)

>>>>Phenolic straight edge? Interesting. I didn't know they existed.<<<

try one you might like it


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## realcowtown_eric (Feb 4, 2013)

WTG Ron…

Most of my straight edges came from garage sales…tucked in a corner with garden tools. That's where I found my slick….

http://www.oldtoolphotos.com/toolphoto.asp?photo=255

course it didn't look like that when I found it…it had an old shovel hande and they thought it was an ice chipper !!!

and this is what I did for tile layout around a kitchen island, augmented by a bosch laser flooring tool..

http://www.oldtoolphotos.com/photos/images/tn/Other_Tools20101114154998610.jpg

Once you got one, you never know when you'll need another…

Eric


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## Whiskers (Nov 6, 2012)

One negative to something like Phenolic, You can't take a cutting blade to them, if you do you will knick it, and make it a irregular edge. A good hard metal edge is better if you need to scribe with a marking knife, or cut with a knife.


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## knockknock (Jun 13, 2012)

Whiskers has a good point about using a knife (as this is in the hand tools section). I switched from an aluminum straight edge to a steel one, because I was shaving it with my marking knife.


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## redSLED (Mar 21, 2013)

My curiousity gets piqued when people spend $75+ for name brand levels just to have a straight edge in the shop.

For straight edges, just go to a metal supplier and buy a few desired lengths of straight thicker-than-big-box-store aluminum angle or square tubing, and take care not to drop or bang them around. If these are not straight enough for you then your measuring/tool-jig setups/handling or eyesight abiliities need improving if your projects dimensions are "off" much of the time.

To make your own long shop level, line up your aluminum angle/square tube side by side with an existing good level, and epoxy/contact cement on some $5 bubble levels to your aluminum. Then just add oak, walnut or other straight cutoffs to your DIY aluminum straight edge/level to impress your shop visitors.

And remember to switch away from using a marking knife against an aluminum straight edge. Light-medium drawn pencil lines that sand off later have always served me well.


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## NiteWalker (May 7, 2011)

Do projects need the precision? Of course not.
Do machines need it? Absolutely. You reference off of your tools surfaces, and error coming off the tools can be cumulative and, that 1/64" gap suddenly becomes 1/8" or more.

No, you don't need starrett's for everything, festool tools aren't needed, bridge city, etc.
But they're nice to have.
It feels good to have quality tools that you can depend on.


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## Purrmaster (Sep 1, 2012)

My hope is that the Veritas steel straight edge will serve as a "master" straight edge I can use to compare other things to. Basically it will be the reference tool. I'm sure it's not as perfect as a Starrett but it will probably be more than good enough.


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## NiteWalker (May 7, 2011)

The steel veritas straight edges are flat to within .001" on the 12" and 24" versions and .0015" on the 36".
Plenty straight for machine setup and as a master reference.

The aluminum ones are flat to within .003" over their lengths, which is also good enough for machine setup, but the steel ones are less affected by temperature, dings, etc.

Like I said, I'm happy with my 24" and 38" aluminum edges, but a steel one would be a nice luxury to have.


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## Ocelot (Mar 6, 2011)

I have to say that I'm always surprised to hear people say that they choose "tougher" precision measuring tools because they "take a drop" better or don't get beat up in the toolbox. I can honestly say I've never dropped a square, caliper or straightedge. I just treat them like they are made of glass and I don't have any problems!  I don't toss them in a heap of wrenches or hammers and such. Sometimes they just stay out on the bench, but they have their own storage places - just a drawer or a nail on the wall, nothing fancy.

-Ocelot


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## Purrmaster (Sep 1, 2012)

I try not to drop and smash my tools. But it happens. I accidentally knock a tool off the bench and onto something metallic. Or I think a tool is hung up and it falls off the nail. Even my Lie Nielsen block plane (which I treat very gingerly) has been dropped a couple of times, despite my best efforts. Things happen.


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## MrRon (Jul 9, 2009)

Ocelot/Purrmaster I totally agree with you. I have about $1000 worth of precision measuring (I also do metalworking) and have never dropped any one of them. If I did, I would probably cry like a baby. I respect them and take extreme care of them. I have a Starrett combination square that I use to check cheap squares that I use for everyday use. That square is kept in a felt lined drawer as a master square.

Just for your information; Starrett, while being recognized for it's quality and precision, is no longer the world leader. Other precision tool manufacturers, like Mitutoyo, Mahr and some Swiss and Japanese companies are equal if not better. Starrett now has some of their tools made in China, besides having plants in the UK, Mexico, Canada and Brazil.


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## JimHouston (Mar 20, 2014)

Recently I ran up on the straightedge dilemma while doing a project for myself. Over the years I never invested in one and I finally decided to treat myself. Well I found out you can spend a ton of money on a straightedge.

It all depends on how accurate it needs to be and what length material you will be using the most. I figured a 72" to 96" would be really nice. Well the prices ran from $1190 for a Starrett Steel Straight Edge, 72" Length, 3-5/32" Width, 9/32" at .0002 accuracy to a Johnson aluminum 72" x 2" x 7/64" for around $25.00.

Guess which one I picked? I bit for the Johnson and got bit in the process. They are way to flexible to really trust for accuracy and I was not impressed at all. I decided to keep it for sheetrock and stuff like that.

Now I was back to square one and looked around for something better. I found a 72" McMaster-Car for $372.00 which is high quality steel and very accurate. Being retired I just could not go for that but I wanted to. Then I found a flooring supply house with a Gundlach steel straight edge 72" x 2-1/2" x 1/8" which would probably do the job for $60.00.

Well I suffered through the job with the Johnson cussing it all the way. If I was still in my construction business I would probably buy the McMaster for the long haul but I can't justify it now. Well I know you didn't want to hear about all my misery but I hope the comparisons helped some. Jim Houston


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## Purrmaster (Sep 1, 2012)

The Starrett stuff, while undoubtedly excellent, is horrendously expensive. One of their longer steel straight edges was a couple of grand. If you're General Motors and need to make a bunch of parts in your machine shop such a tool makes sense.

I suppose eventually there will be fully electronic ways of doing those kinds of measurements.

I think the Veritas straight edge is kind of in the middle in terms of perfection. That should be enough for me.


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## NiteWalker (May 7, 2011)

Any straight edge longer than 48" is overkill for machine setup IMHO. 36" is the set spot for a matter so reference with a 24" handling most day to day needs.


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## Purrmaster (Sep 1, 2012)

I'm going for a 36" incher. So it looks like I hit the sweet spot. I hope.


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## unbob (Mar 10, 2013)

These bars sitting on top of the old Grizzly jointer are Pratt & Whitney made parallels, used for work set up on metal working machines.
One shown is 48" the other is 25" long, they are 1 1/4" X 1 3/4". Precision ground on all sides and made of hardened tool steel, very accurate
These tools are usually in matched pairs, but singles can be found at used machine tool dealers.
I find these ideal for adjusting my woodworking machines.


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## Purrmaster (Sep 1, 2012)

Pratt and Whitney? Don't they make aircraft engines?


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## unbob (Mar 10, 2013)

Pratt & Whitney made machine tools first. They were known for small bench lathes, then heavy precision lathes, and high accuracy jigborers made up into the 1970s.
They also made measuring tools such as their Super Micrometer, a 70lb bench micrometer reading directly in fractions of a tenth.
A funny thing P&W, was proving accuracy in the 1920s with the jigborer that some say is not possible today. Bring that fact up on any of the "controlled" machinist web sites, and watch them freak out !


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## MrRon (Jul 9, 2009)

Way back in my memory, there was an article on one of the woodworking sites on how to make a straightedge from wood. I think it entailed making two straightedges at the same time and working one against the other until they were straight. Someone else may remember where I saw it.


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## unbob (Mar 10, 2013)

The first flat surfaces were created using three pieces, working them together in sequence by either lapping or hand scraping.
There would seem to be no reason it would not work with wood, it would need 3 like size pieces, and redone often because of material stability.


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## Purrmaster (Sep 1, 2012)

If you used the proper quartersawn or riftsawn lumber might you be able to make a very stable wood straight edge?


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## unbob (Mar 10, 2013)

Yes, MrRon may have hit upon a reasonable solution!
I would think powdered chalk could be used to find the high spots, then using a wood scraping tool, and perhaps burnishing tool to work the pieces flat.


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## Purrmaster (Sep 1, 2012)

I still say I'd like to see ceramic straight edges. Though heaven knows how much they might cost.


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## Benvolio (Feb 10, 2013)

from a forging point of view, remember alu melts at around 500 and steel around 900-1100 degrees C. That has huge costs implications for furnace fuels which affects price.


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