Straightedge bowed

[tony mashadi]

Hello-
I am a relatively newbie non-professional woodworker. Although I have heard from many that buying a used percision tool is not the best idea, i went a head and purchased a used suburban tools 36" steel straightedge which is sold new for $136 i believe, from ebay. I paid around 80 for it and the guy said its unused in new condition. Now that I have recieved it its badly bowed. Now the edge still seems straight based on my test by trying to push paper under it as its sitting on its edge on my tablesaw top (havnt recieved my filler gauge yet). So my question is, does this effect the accuracy or any problems with things i would be using it for (adjusting my tools). I want to know if I sould return it or at least leave a negative feedback on ebay or this is not a big deal. Dont want to unfairly effect the guys reputation if this is not a big deal but the dude did say its in perfect, new, unused condition. The bow is significant enough that it seesaws a good 1/8" up and down when layed on its face (wide side).
Thank you in advance for you responds
Tony

[Bill White]

Although the straight edge may not be affected, I would not be too happy with spending that for an edge device that was badly warped either edge or flat.
Bill

[Bill Huber]

I agree with Bill, it may be just fine and do the job you need it to do but I think I would give the seller a note and see what they have to say.

[Ken Fitzgerald]

Tony,

When you buy something used on ebay, the old adage "Buyer beware" definitely applies and yet, a person should be able to reasonably trust what is advertised there. If you are concerned the bowing will affect your use of the tool, I'd try to contact the seller and give them a chance to make amends.

Does the "straight edge" verify the flatness of your table saw? Even machined surfaces on table saw beds are often not "flat". Manufacturer's tolerances often run in the 0.010" to 0.015".

That being said, it's a "straight edge". If it was me, if I really liked the tool, I would test the "straight edge" and if I found it accurate, I'd mark the bow side so it was always identifiable and use it with the high side up, pressing down on the high spot to flatten the bow. If the straight edge remains straight using it as I stated, it's your call.

BTW......Welcome to the Creek! It's neat, civil place where we can all share information concerning woodworking and related subjects.

Please take time to read the Announcement threads at the top of the forums with special attention to the one titled "Read Me First".

[glenn bradley]

Its a little late to close the barn door but, the 36" steel straight edge from Lee Valley has served me well for years. Even though the price has risen (along with everything else) it it still only $87.50 brand new. I assume you are stuck with the one you bought so this may be moot.

[John Schweikert]

I would just return it, as long as the auction permits. Not all ebay items allow returns.

In place of that item, here are several options which cost same or less (and for a week there is free shipping from Lee Valley for anything over $40)

Veritas aluminum 38" straightedge with .003" accuracy over the length for $38.50
http://www.leevalley.com/US/wood/page.aspx?p=50074&cat=1,240,45313

Veritas steel edge 36" accuracy over the length .0015" for $87.50
http://www.leevalley.com/US/wood/page.aspx?p=56676&cat=1,240,45313,56676

Woodpecker 36" straightedge also with .003 accuracy over the length for $59.99
http://www.woodpeck.com/serx36.html

[Jerome Stanek]

Are you sure it is the straight edge and not the saw table

[Tom Walz]

I have beenselling tools for 30+ years and the number one rule on quality is that a goodtool is exactly what the user thinks is a good tool. We use that rule. Most of our competitors do the same thing. If you are, a fan of Dr. Deming willrecognize this is a version of his rule that quality is exactly what thecustomer says it is.

This is why wehave a 100% satisfaction guarantee as, once again, do many of our competitors.

Rulers, Squares and Straight Edges
1. There are generally differences among squares,rulers, and straight edges. Straightedges are generally much more expensive and are made to much tighter tolerancesthan rulers or squares. For an example, andthree-foot Starrett straight edge sells for hundred $194 on the Starrettwebsite and is guaranteed accurate to “Accuracy (in) ± .0002” per foot”. This is 0.0006” over 3 feet or0.001666%.

Judging by thepaper test it may be "flat" depending on how you define theterm. I figure paper to be about 0.003" to 0.004" thick. Cigarette cellophane maybe 0.001" to 0.002".
Therefore, figure it is maybe bowed 0.003" over a 36"length,which is 0.008333%.


A Woodpecker’s WoodworkingRule 36", (Woodpeckers WWR36) is $37.99 on our hockey game on what place e. websithttp://www.carbideprocessors.com/woodpeckers-wwr36-woodworking-rule-36/

They guaranteethem to 0.001” per 12” or 0.003” per three feet. However, this is sold as a “ruler” and not asstraight edge. It also sells for $37 vs.the $136 you paid.

2. Measurement is a matter ofopinion.
SI Units:Length
http://www.nist.gov/pml/wmd/metric/length.cfm

The definitionof the meter (m), which is the international unit of length, was once definedby a physical artifact - two marks inscribes on a bar of platinum-iridium. Today, the meter (m) is defined in terms ofconstant of nature: the length of the path traveled by the light in vacuumduring a time interval of 1/299, 792, 458 of a second.

FAQ: When didthe metric redefinition of the inch occur?
In 1958, aconference of English-speaking nations agreed to unify their standards oflength and mass, and define them in terms of metric measures. The American yard was shortened and the imperialyard was lengthened as a result. The newconversion factors were announced in 1959 in Federal Register Notice 59-5442(June 30, 1959), which states the definition of a standard inch: The value forthe inch, derived from the value of the Yard effective July 1, 1959, is exactlyequivalent to 25.4 mm.

However, theseare nominal or theoretical measurements. Most machine shops are not set up to measure the distance light travelsin a fraction of a second. So measuringtools are calibrated according to measuring tools, which are calibratedaccording to measuring tools (and so on) that are calibrated by NIST.

Then thesemeasuring tools are used by people to measure materials that move, even whileyou are measuring them.

In the late1980s we were a second-tier supplier to Boeing aircraft. We would do work for Boeing suppliers. In one case, we built an aluminum mold for aplastics company that was going to use it to mold gasket for the cockpit of theB2 bomber. This was about 8 feet longand very complex with multiple catenary (or funicular). We worked on this for weeks. The last two weeks we very carefully removedabout 0.001” then let it rest overnight. The next day we would do our measurements, remove material as we thoughtappropriate and let it sit.

We were doingthis inside under artificial light.

We deliveredthe part in the morning and the customer started inspecting it on the loadingdock. Things were looking pretty good atthe start then the sun moved to where it was shining on the part through theopen loading bay door. As sun warmed upthe part, it moved. It was a big part;about 8’ x 4’ maybe 3 feet thick in places down to 1 foot thick in other places. We had done our very best to eliminatestress but the sun warmed it up and the part moved. Different parts of the mold moved differentlydepending on the thickness, the shape of the curve and how the sunlight impactedit.

We found outlater that the government had changed the design so the drawings we had were nolonger correct. The customer told usthat Boeing was not going to accept the part so they were not going to pay usfor it.

There were noexact specifications on how to measure the part so they could measure itanywhere they wanted to, to prove that it was wrong.

This story maybe relevant here because you run into the same sort of thing with straightedges. Typically, straight edges aremeasured against granite blocks or against other straight edges but neither ofthese is going to be perfect.

You can measurea straight edge against itself. You lay itdown on paper and draw a line. Then youflip it end over end and side to side. Theside you used to draw the first line should now be facing that line from theopposite direction. You draw a secondline and look for any variation between the two lines. This is a pretty good way to do it withrulers and squares but may not be accurate enough for straight edges.

3. How much accuracy do you really need?

Accuracy islike most everything else. The more youget the more it costs. Wood and similarmaterials do not lend themselves to ultra-precise manufacturing. To a certain extent, there is no definiteedge on wood because the fibers tend to be pulled out during cutting and theedge fuzzes a bit. Wood moves with bothtemperature and humidity. Wood is also avery forgiving material. Why pay foraccuracy down to 0.0001” when that much will not make any difference to theassembly or finished appearance of the joint.

4. In a pissing match nobody wins and everybody gets their shoes wet.

A. Maybe you do not need a straight edge thatstraight since you are working with wood. On the other hand, you want one, you paid for one, and you are to haveone.

B. Maybe the supplier can give you a better oneand take back the one you have.

C. Maybe the supplier will refund your money andyou can buy a Starrett straight edge or a Woodpeckers ruler from us.

C. Maybe they will not and you sort of werescrewed. I do not like it when ithappens to me but sometimes it is just not worth fighting.

D. Maybe you take the straight edge you haveand, if it is massive enough to make it worthwhile, you bring the edge into thetolerances you want it. (Make sure thetool is beefy enough that it will not move too much as you work on it, as theweather changes, etc.)
You might likethis since you seem to really value precision.

Conclusion:

In any case,welcome to the forum. There are many, manyfine folks here. Woodworkers in generalseem to be a higher class of people than the average.

It took me awhile to come the realization that maybe checking here before I bought somethingwas a good idea. The last cordless drillI bought, I bought because of the reviews here, and it was a brand I had notconsidered. It was well reviewed and hasturned out to be a very good tool.

[John Coloccia]

I would return it. It needs to be reasonably straight or it will annoy you to no end. What's more, once it's warped like that, the slightest twist will absolutely ruin the accuracy of the edge. Slight imperfections in the surface your're measuring will also throw everything way off if it happens to slightly lift the straightedge at the warped end. Basically, the warp at the end magnifies the imperfections in the straight edge and in the surface you're measuring, just as any other lever would. It doesn't need to be absolutely pin straight, but you're describing a huge bend in what should be a tool with reasonable precision. Yours is so bad that if you want to lay it on a sheet of plywood and mark a line, you couldn't do it because the edge would ride up the pencil point! :)

I have a long straight edge that I bought a few years ago. I cheaped out. I won't mention the brand, but it mostly just hung on the wall in the provided holder, and it's all warped now and absolutely worthless.

[Tom M King]

I'd return it, but not be so fast to leave negative feedback unless it's really earned. If the seller agrees to a quick solution by accepting the return, I'd still leave positive feedback once your payment is returned.

[tony mashadi]

Wow, thank you all so very much for all the great responds. I learned a great deal. I will contact the seller to see what he can do to rectify this. While the side edge seems reasonably straight (im yet to confirm the degree of that too) the wide side is so bowed that you can easily see it by naked eye so Im sure its not my tablesaw top that make it seem that way. I absolutly agree with all of you guys. Lesson learned. i will see if I can return and buy one of the ones recommended here. If not I would bite the bullet and perhaps get a lee valley later on anyways. To be honest I think buying a 48" one would have been a better choice anyways as I beleive the 36 is not long enough for my DJ20 jointer. Being a perfectionist to an OCD level I had thought I would use this 36" steel straight edge for some stuff and would also use it as reference to compare to the longer straightedge that I had planned to buy in future. It was advertised as pierce n taft and I figured for the price it would be good to have 2. Well, it didnt quiet work out as I thought :) I guess you do get what you pay for! Again, I thank you all for taking your valuable time and giving me such detail information. This is a wonderful forum and I'm looking forward to becoming an active member and hopefully a supportive one.
Thanks.
Tony

[tony mashadi]

Mr. Walz, thank you for your detailed respond. I found your website (carbideprocessors.com) from your profile. I will definitely check out your products and consider them in my future purchases. Being new to woodworking I'm sure I will continue to need to add many tools and accessories to my shop and I would love to buy from friends of this forum :)
Thank you
Tony

[Jim Matthews]

I keep a straightedge to verify the flatness of the tools I use to inspect pieces I make.

It is the "standard" that I check, if I suspect my tools aren't accurate.
I've been using a pair of 18" long aluminum levels as winding sticks
and a longer set of levels (24 and 48") for checking edges.

I haven't had a board jointed to the accuracy of my 48" level fail to glue up, yet.

Meantime, the straightedges are kept oiled and wrapped in protective storage paper.

I'm with the others here, if your seller will accept a return - send it back and express your thanks.
Then reconsider the precision with which you must check things.

If you're a machinist by training, the imprecision of working with a material like wood might require reconsideration of your standard.
You'll be dealing with increments much larger than machining metals.

[Myk Rian]

Run it through your jointer and planer.
:D Sorry. I just had to.

Lay it on a couple blocks by the ends. Put a few pounds in the middle, and let it set for a few days.
Just might get the bow out of it.

[tony mashadi]

Thanks for the suggestion Myk. Fortunately the seller agreed to take back so I'm just out the shipping fee.

[tony mashadi]

Jim I agree. I'm sure I can get away with less accuracy. Its not my training that causes this, its my OCD :)

[Ken Fitzgerald]

Tony,

There is nothing wrong with one expecting something to meet advertised standards.

I ordered a new 36" straightedge from one of the more recognizable companies. They aren't the manufacturer, however. I paid roughly less than $50. When I received mine it didn't meet the advertised specifications for straightness. It was out of spec in the last 4" at one end. I called the company, they sent a new one and told me to keep the old one. The 2nd one arrived and was dead on. It verified that the original one didn't meet specifications in the last 4". I marked that original one and kept it too.

That being said, wood is a dynamic material. I doubt any of the wood I use will meet the advertised specification for my straightedge!

[Tom Walz]

OCD- is how you get great.

[Andrew Pitonyak]

Mr. Walz, thank you for your detailed respond. I found your website (carbideprocessors.com) from your profile. I will definitely check out your products and consider them in my future purchases. Being new to woodworking I'm sure I will continue to need to add many tools and accessories to my shop and I would love to buy from friends of this forum :)
Thank you
Tony

They have awesome service, offer a discount to creekers, and, as you just noticed by his response, they know much about what they sell.

If you can, return the bowed straight edge. There are too many choices not to get something that you are happy with if you can. If you cannot return it, perhaps you can make it work.