Curiosity about straight edges and metal

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Forum topic by Purrmaster posted 03-23-2014 04:31 AM 3700 views 0 times favorited 45 replies Add to Favorites Watch
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915 posts in 2118 days

03-23-2014 04:31 AM

Topic tags/keywords: straightedge straight edge steel aluminum

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.

45 replies so far

View shampeon's profile


1775 posts in 2208 days

#1 posted 03-23-2014 04:42 AM

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.

-- ian | "You can't stop what's coming. It ain't all waiting on you. That's vanity."

View Purrmaster's profile


915 posts in 2118 days

#2 posted 03-23-2014 05:16 AM

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

View Ocelot's profile


1980 posts in 2663 days

#3 posted 03-23-2014 05:16 AM

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.

View realcowtown_eric's profile


609 posts in 1962 days

#4 posted 03-23-2014 05:18 AM

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
from the flooring world

from the machinists world.

Hope this adds a tad of perspective

Eric in Calgary
search and you will find!

-- Real_cowtown_eric

View woodchuckerNJ's profile


1276 posts in 1659 days

#5 posted 03-23-2014 06:32 AM

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.

-- Jeff NJ

View Jerry's profile


2656 posts in 1673 days

#6 posted 03-23-2014 07:06 AM

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.

-- There are good ships and there are wood ships, the ships that sail the sea, but the best ships are friendships and may they always be.

View bowedcurly's profile


519 posts in 1754 days

#7 posted 03-23-2014 07:48 AM

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

-- Staining killed the wood<<<<<>>>>>Dyeing gave it life

View Purrmaster's profile


915 posts in 2118 days

#8 posted 03-23-2014 09:07 AM

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.

View TheWoodenOyster's profile


1317 posts in 1960 days

#9 posted 03-23-2014 12:12 PM

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.

-- The Wood Is Your Oyster

View Scott's profile


153 posts in 2997 days

#10 posted 03-23-2014 12:52 PM

Shampeon, that was pretty funny.

View Jim Finn's profile

Jim Finn

2657 posts in 2947 days

#11 posted 03-23-2014 01:25 PM

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.

-- Website is No PHD just a DD214 and a GED

View MrRon's profile


4794 posts in 3268 days

#12 posted 03-23-2014 06:06 PM

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.

View MatthewG's profile


85 posts in 2804 days

#13 posted 03-24-2014 03:46 AM

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 :)

-- Matthew, from beautiful Wisconsin USA

View shampeon's profile


1775 posts in 2208 days

#14 posted 03-24-2014 03:50 AM

Scott: glad someone got my joke. 8^)

-- ian | "You can't stop what's coming. It ain't all waiting on you. That's vanity."

View realcowtown_eric's profile


609 posts in 1962 days

#15 posted 03-24-2014 03:54 AM

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….


-- Real_cowtown_eric

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