Tactile Text per the new ADA Specifications

[Keith Outten]

The recent revision of the American with Disabilities Act includes a change that prohibits tactile text with sharp edges. If you are using a laser engraver to cut your tactile letters, numbers and icons for ADA signs you are probably in the process of developing a technique that complies with the new Specification which affects buildings that were started on or after March 12th 2012.

There are several options available that will provide a softer edge, note that I did not use the term beveled edge because a bevel is not required. The ADA specifies edges that are "not sharp", this is a vague description that may be difficult to prove should you be questioned by a building official or customer representative.

I have been working on a means of processing my tactile characters that will allow me to continue cutting them with my laser engraver. I have not perfected the technique yet but I am close enough at this point to share some details and concerns.

Vibratory Tumbling

For about ten days I have been experimenting with a vibratory tumbler using several types of abrasive media. At this point I have learned that Aluminum Oxide (16 grit) leaves a terrible coating on plastic characters and although it will soften the edges some I believe that it is not abrasive enough. I have had better luck with glass media, a medium grit leaves only dust on the characters that washes off easy enough but the edges are still not soft enough to make me happy. My run times have been from 2 hours to 8 hours at this point with basically the same results. I feel that my next step is to find another abrasive media that is specifically made for plastic, if this exists. My Internet research has turned up references to abrasive media for plastic but I haven't found a source to purchase it yet. Possibly someone here has had experience with vibratory tumbling soft plastic and can help me find the right media for the job.

Below you will find a couple pictures of the tumbler I am using. It is an inexpensive machine from Harbor Freight, this five pound model costs about 59 bucks. There is an 18 pound model that sells for about 160 bucks that I will purchase if I my final results provide an acceptable edge.

[Rich Fennessey]

This certainly doesn't get any simpler huh? I've had some issues getting a consistent depth of cut on my Romark plastic. I noticed the corian pieces I have definitely vary by a couple hundreds of an inch which has caused me issues. I'm going to try a different bit - more on that later. Just like Thomas Edison - we know of different ways that don't work.

[Scott Shepherd]

Keith, do you have a link to the standard? I can't find anything updated like that on the doj site. I might be missing it, but I sure can't find it.

[Ken Dolph]

Keith

Before painting or even after, go over the surface with a Maroon Scotch-Brite on a random orbital. Also a heavy coat of clear coat after painting will help.

[Keith Outten]

I have resolved this problem by using an aquarium stone that I was able to find at a Pet Store. It took almost six hours of vibratory tumbling but the results are very smooth edges that should meet the specification easily.
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[Ken Dolph]

May I ask what material the letters are made of?

I found the regulation in http://www.ada.gov/regs2010/2010ADAS...Astandards.htm

"Advisory 703.2 Raised Characters. Signs that are designed to be read by touch should not have sharp or abrasive edges."



It appears to not be part of the regulations but some inserted advice. That is why "sharp" is not defined. In fact it is not defined anywhere in the document. With all of the exactness of the document I find that odd.

Since the letters should not be non-glare (703.5.1) I believe that a quick touch up with a maroon Scotch-Brite might be sufficient.

Just my 2 cents.

[Scott Shepherd]

Keith, can you point to exactly where you are seeing that? I've read it over and over and I can't locate anything about that. I'm obviously missing something. I did see it mentioned that it was said to be easier to read when it was smooth, but I can't find anywhere where it says it's required.

[Keith Outten]

Steve,

Ken found the section that applies:

http://www.ada.gov/regs2010/2010ADAS...#pgfId-1010471

703 Signs

703.1 General. Signs shall comply with 703. Where both visual and tactile characters are required, either one sign with both visual and tactile characters, or two separate signs, one with visual, and one with tactile characters, shall be provided.

703.2 Raised Characters. Raised characters shall comply with 703.2 and shall be duplicated in braille complying with 703.3. Raised characters shall be installed in accordance with 703.4.

Advisory 703.2 Raised Characters. Signs that are designed to be read by touch should not have sharp or abrasive edges.

703.2.1 Depth. Raised characters shall be 1/32 inch (0.8 mm) minimum above their background.

703.2.2 Case. Characters shall be uppercase.

703.2.3 Style. Characters shall be sans serif. Characters shall not be italic, oblique, script, highly decorative, or of other unusual forms.

703.2.4 Character Proportions. Characters shall be selected from fonts where the width of the uppercase letter "O" is 55 percent minimum and 110 percent maximum of the height of the uppercase letter "I".

703.2.5 Character Height. Character height measured vertically from the baseline of the character shall be 5/8 inch (16 mm) minimum and 2 inches (51 mm) maximum based on the height of the uppercase letter "I".
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[Scott Shepherd]

Wow, that's about as clear as mud. What's that mean? Define sharp. It says "Sharp or abrasive". My interpretation of that is you shouldn't be able to cut yourself on the edge, or it shouldn't be abrasive because it could cause damage to one's fingertips. I certainly don't read that as "all raised letters needs to have a broken edge".

My guess is you'll never find a person in the DOJ that is qualified to clarify that. I'd bet my paycheck that you could call the DOJ and get them saying whatever you lead them to say. If you asked it like this "Does sharp mean it just shouldn't be able to cut someone, like a raised metal letter with a razor sharp edge", they'd say "Yes", or if you said "Does that mean they have to have the edge broken on every edge", they'd say "Yes".

My first suggestion would be to cut the letters with the following method, if you believe they need to have the edge broken- copy the text in the same location, make one of them one color, one another color. Cut the letters, then with the second color, take the machine power down and way out of focus, perhaps .180-.200 or so, and run the second color. In the Trotec driver, just put that amount in as an offset and it'll move it automatically. Then you need to play with the power some so it's doing a very light melt on the top edge.

I tried it, it works fairly well. I didn't fine tune it, but my initial tests proved to me that it's a method worth fine tuning.

Let the laser do the work, not you

[Mike Null]

I agree with Steve though I would probably test an outline with a contour. The outline would be the lower power (round over line) and the contour would be the cut line.

[Keith Outten]

I thought about using a second pass to break the edge but It seems to me that I would have to run the edge softening pass first then cut out the letters and numbers. Once they are cut out they rarely stay in position, they shift at least a little bit no matter what type of vector cutting table I have used.

Steve, I agree with you concerning the definition of "Sharp" in the spec. It is pretty rare in my world to see this type of ambiguous language in a technical specification. I'm sure that the number of interpretations of the term sharp will be equal to the number of people you ask to define the term. Once I have an established technique I am going to submit a sample to the BCOM organization in Richmond Virginia and hang it on the wall in case we are ever questioned in the future.

The vibratory tumbler works perfectly leaving a very soft round edge but it also leaves the letters and numbers a bit dirty. I am considering a second run in the tumbler with walnut shells to clean them up. This is starting to add up to a big pain but the stakes are pretty high considering the profit margins involved. The good news is that the tumbling runs don't require any direct labor other than loading and unloading the barrel with the exception of having to sort thousands of letters and numbers after the tumbling run.
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[Scott Shepherd]

Great point Mike, I think that's worth a try.

Keith, don't discount the method before you try it. Yes, the letters do move a little, but the machine is so far out of focus, the beam is probably .060" or so in diameter. You just want some energy to hit that edge, doesn't have to be precise, as the plastic will melt on the edge. With Mike's offset idea, I think the risk of messing the top of the letter up is even less.

I've been using tumblers since the 80's and I can't imagine having to tumble letters. It works for you because of your method with the corian, but for normal ADA signs on rowmark type products, where the ADA material already has the adhesive on the back, you'd be out of luck.

My guess is some moron made a bunch of laser cut metal letters with sharp edges and installed them some place important, which prompted people do say "Well, it didn't say they shouldn't cut someone's fingers if they used them", only for the regulators to look at the code and say "You know what? They are right, it doesn't say that".

My first thought (well any thoughts when it comes to ADA regulation) was that the vacuum forming people had bought their way into the code. Vacuum forming is the up and coming method that's going to give photopolymer a real run for it's money. Just as some companies (no names mentioned) spent so much time and money making sure the regulations made their product more attractive, I thought for sure that's what was happening here (and it still might be).

I stick by my guns- define sharp. Is sharp anything less than .001"? If I have a .002" broken edge (which I can clearly measure and prove), is it no longer "sharp"? Or is sharp defined as the inability to scrape or cut oneself on that object?

My guess is that it has zero to do with us and how we make signs, using plastics that are fairly soft, but more so someone that's done something out of metal.

I'm not modifying my method over that wording.

[Keith Outten]

Steve,

In the interest of saving a lot of time and keeping things as simple as possible I will spend some time experimenting with Mike's suggestion.
At least I know that the vibratory tumbler will work if all else fails.

I am off from work at CNU today trying to get two storage buildings I moved around my yard Saturday back level and on blocks. Then the long task of moving all of the contents back inside the buildings. Yesterday I was so sore I couldn't lift a finger much less work on the buildings. I also moved my 3000 gallon steel tank that I use for my shop chipbox Saturday.
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[Ashton Waters]

Keith,

Have you thought about ceramic pellets. They are usually used for polishing metal but look like they could soften sharp edges. It is also cheap. Check out this possible source. http://www.ceramiccrafting.com/page/1099535.

Ashton

[Keith Outten]

Ashton,

Thanks for the tip, I will take a look at the ceramic pellets ASAP.
The stone I used did a good job but the letters and numbers need to be cleaned after they have been tumbled. Another step in the process means more time invested so I will experiment with the laser technique before I spend more time with the vibratory tumbler.

Right now I am neck deep in an a sign install in a huge residence hall. When I get home in the evening I don't have enough energy left to work in my shop, the building is running late and the signs have to be in before July 10th. We are having to work around construction workers and are constantly waiting for walls to be painted before we can install signs, this one is going right down to the wire.
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