pic: Floating Zip Tie Chain Tensioner
 

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Thats sweet. How do yall make sure all the zipties are in place. Does it work as well as mcmasters? Did yall ever have problems with zipties breaking and the tensioners falling off?

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Ha! That is a neat idea!

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The zip ties fall in the three slots on the top and bottom and they actually worked better than mcmaster's for us. The reason being is that tensioning them meant replacing a zip tie. So if you didn't have enough tension, pull the zip ties. Too much, cut them and put a new one. The zip ties never broke because they were rated at 75 lbs each. We implemented them after I saw that mcmaster's were giving us way too much trouble. These can be made by buying u channel of uhmw or by cncing out blocks of uhmw.

We replaced the mcmaster's during Nationals with our new ones.

Re: pic: Floating Zip Tie Chain Tensioner
 

very nice, were there any problems at the championship?

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The only one was that we did not cut the ends of the zip ties so they got stuck to the chain. That was a nightmare.



Here's a darker render.

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hmm i would expect that was second nature, were you in a rush?

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Yes we were, it was a minute before our 4th match at nationals.

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patent it.


i'm serious.

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how???

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I am sure there are a ton of guides on how to do that online, Google it!

Like try this, http://www.uspto.gov/web/patents/howtopat.htm

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You've got to file an official patent.

IT GETS EXPENSIVE TO PATENT SOMETHING:

but the first thing to do is to have a researcher do a patent search...where somebody searches through all the previously issued patents to see if there is an invention that currently exists.

if there isn't then you can file for a patent which tend to take several years to issue.

Patenting this could get pricey, but it may be something your team is interested in.

I think it is a great little idea, and great little ideas should be taken care of.

Re: pic: Floating Zip Tie Chain Tensioner
 

Back in '07 I saw Team 8 put a zip-tie around a chain on their roller-claw :yikes: Now there's a simple method!

I'm curious about what happens when the blocks twist around. I mean, the zip-ties aren't gonna hold them perfectly flush like that. What happens when they twist and jam into the side of the chain?

We had these kinds of problems when we used delrin tensioners in our '06 drive train. The chain was always grinding against the sides of the slots we cut in the delrin. Wasted a lot of power that way.

Very creative though. I like the way you think :cool:

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You just gave everyone here a "Why didn't I think of that?" moment.

Great Idea.

If you go along with Brandon's Idea to patent, and possibly sell it, may I suggest small Hose clamps as an alternative to zipties? It would make it larger and heavier, but also possible to adjust in two directions. It would also keep the tensioner in one piece, so that users cannot lose the second half of it. Finally, it would make it more robust. This would help its use in applications with larger chain/greater power use than FIRST.

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do remember that if you patent it you have to give everyone due credit and a piece of the pie

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Wow. This made my day. My only question is: is the uhmw that you use tough enough and how thick is it? Does it wear down after a few matches? I'm guessing that it's easy enough to make plenty of extras out of a hunk of u channel. Did you replace the tensioner often(every match)?

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This really is a great idea!!

Not to get too off-topic, but while developing a patent for this idea can be very pricey and time-consuming, there is another option. You have to remember what a patent is for: to document that this is your idea and you came up with it before anyone else so that no one else can profit from it (except for you, of course).

First, create a white paper on your tensioner, or a detailed document describing the device and its development. Be as detailed as possible, and include as many options as your team can think of (BTW, I like the hose clamp idea). Include drawings, photgraphs, names, etc. Once you have that, file an application for a copyright on the document (I think it's about $40 for the application fee). Now, if anyone else takes your idea and goes to market with it, you have proof (with a critical government timestamp, no less) that you came up with the idea first. With that document, you could give that to any lawyer who would gladly sue that person/company that's using your idea for a piece of the profit. I know of several people who do this regularly with ideas they develope.

Sure, if you're going to take it to market yourself, a full-blown patent might be the way to go. But, if all you want to do is protect your future rights to your invention, a copyright is a whole lot cheaper. To top it off, if I remember correctly, while an expensive patent lasts only a few years (relatively speaking), a copyright lasts the lifetime of the filer plus 70 years.

But getting back on topic, I agree that this tensioner idea could be something that you and/or your team might want to protect.

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This is why I love Madtown's designs. simple and effective.

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There is a major flaw in your idea. There is something called the "public disclosure clause" for patents. Basically as soon as you show your idea in a public place (a regional, or chiefdelphi would defiantly count) you have started a one year clock. If you don't file a patent within that time frame then it is considered public domain and regardless of your time proof. That being the case anyone could come to market with this thing and you would have no protection.

If you don't wish to do a full fledged patent at this time you can always file a provisional patent which adds one year of protection to give you the time to file a patent if you want.

In my honest opinion I wouldn't worry about patenting this. If you go do a quick patent search for "chain tensioner" you will see literally hundreds of different methods. While what you have made has quite alot of use in the robotics community the use for industry is minimal, where size and weight constraints don't really exist in many of the applications.

I don't mean to discourage you and I think that everyone should try for a few patents in their lives but you need to decide if getting a patent will be worth the effort and experience. If your interest is selling this tensioner then just do it, and you don't need a patent. For example look at andymark, they sell loads of items and don't have patents on most of them.


As for the design I like the concept alot, I would make sure that you add a chamfer or round on the lead in edges both on the zip tie holders and the chain channel. UHMW is great for it's lubricity but may not stand up under alot of use which is up to you because these will be cheap and easy to replace. I would look at delrin or some other harder plastics.

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Or you could creative commons license it, preventing someone from stealing your idea for profit, but allowing anyone to copy it for their own use. I am even thinking of how this could be used in my own designs. thanks!

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That's not how CCL works. It's a form of copyright protection only.

When you copyright something, you're asserting ownership of the work (of art, of literature, etc.), but you don't have protection for the engineering information contained inside. So by copyrighting a drawing, you prevent someone from redistributing facsimilies of the drawing, but are not protected against someone reading it and implementing the object depicted. The CCL just changes the terms of the copyright licence to permit not-for-profit use, usually with attribution.

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Hachiban, you might be surprised how flush they stayed. They actually work really well. The zip ties offer enough tension but not too much.

Thanks, hoseclamps would work so much better.:)

I came up with the idea by myself and the chiefdelphi community gave me the idea of hoseclamps. Do I give credit to the team or to who? Semi confused, probably because I just woke up and have not had breakfast/lunch.

UHMW is pretty good and thatz why i picked it. We have using McMasters floating chain tensioners for about three years. We haven't replaced them for 3 comps and offseason events. So uhmw is pretty good for us. The wear is minimal only if the chain isn't too tight and has a little bit of slop. We used this on our 5th match at nationals. So we have only used these for three matches and a couple of offseason demos. You could make these out of chuncks of u channel or cnc out blocks of uhmw. We never replaced the old tensioner accept when it over tensioned or was getting stuck or when it just wasn't working.

What if I just sell it to Andy Mark??

Thanks for your support guys

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Another thing you might want to try is kevlar. It is a bit more expensive but should last longer and have less friction.:D

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Or you could start your own business manufaturing chain and belt tensioners. Maybe donate some to FIRST for next year's KOP...:cool:

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It would be nice, but it is way too expensive.

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money complicates everything, free ideas for everyone:D
mike d

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Also another question, would teams buy this if they were available???

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Yes, especially if offered in multiple sizes. We've had some issues with our homebuilt non-floating tensioners over the years, and never had enough money to spare for several McMaster-style tensioners.

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What sizes would you want? Currently we have:

1.25 x 2.5

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I meant for different chain sizes. #25, #35.

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They work for either one, just like mcmasters.

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This is a fantastic and simple idea! Now let's hope they don't ban zip ties... We would want #25 chains, but probably only 1.25" in length because we have some short chain runs to deal with from the transmissions.

Have you done any efficiency experiments, e.g. how much efficiency is lost due to these tensioners when compared other methods? Examples include autotensioning (sliding a wheel out like 254/968/etc), simple rotary tensioners that use delrin or similar plastics, or the old adjustable bolt/sprocket method.

If you find that there's more loss (due to increased contact surfact area) you could experiment with teflon or oil-impregnated plastic surfaces. Also, you could change the geometry in the channel itself to be curved convex rather than simply flat. This is how the secondary tensioners on Harley Davidson motorcycles work -- turn a bolt and a convex-curved piece of teflon raises against the chain to fine-tune the tension.

< edit >
Another thing you could do is create a working relationship with a company such as AndyMark or a local plastics mold company, who can mass-produce these for teams and give your team a % of the revenue. The upside to this is that it should be low-stress supplemental revenue for your team. The downside to this is that you miss producing and selling these yourselves, which opens up a whole new can of worms in opportunities for more people from your community to learn and participate in your program.

Food for thought.
< /edit >

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I can't speak for specifically how much loss there is between different types, but the method of sliding the wheel is going to be by far the most efficient, as it's the only style of tensioning that does not touch the chain and add more friction to the system.

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There's an easy answer to that.

It depends on your price point.

Unfortunately, with something this small and this easy to make, your labor (or mill time) is going to KILL you on pricing. Now, if you could get a plastics shop to start cranking them out by the thousands off a small injection mold so that you could sell them for a couple of bucks for a pair... well... I'll tell you one team that would be interested!

Get in touch with AndyMark. I'm sure they go through this all the time and can help you out. Incredible idea!

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An interesting design, and an interesting discussion on IP. (Intellectual Property... patents, copyright, etc.) The CD community does a pretty good job of giving solid information on the challenges and benefits of patents, and dispels some common myths such as the protection offered to engineering designs through copyright.

It looks like these could be mass produced fairly easily on a table saw with some fairly simple jigs. There are also some alternatives to UHMW that are worth considering. A local firm (North Vancouver, BC) produces a graphite/epoxy composite for lubricating the side of train wheels. This is an extremely hard-wearing, low-friction compound that can easily be shaped with wood-working tools, but has the added benefit of lubricating the chain (or wheels) as it slowly wears away. They gave us some and we used this to tension our chains three years ago, with a grooved sliding tensioner that was adjusted cam-style on just one side of the chain. It worked great. But I've lost their contact information, sorry.

As far as the profitability of marketing this design, the tensioners would end up being a fairly low cost item (the raw materials are commonly available and the machining steps relatively simple) so it would require a significant volume of sales to generate a large amount of revenue, and, as mentioned several times, a large amount of revenue is required to justify the cost of a patent.

However it is possible to file for a provisional patent at a much reduced cost ($500 is the ballpark figure that runs through my head), and while that only protects your design for a year, that may be enough time to test market it and/or license the design to someone who is willing to pay the costs of obtaining a full patent.

Whether or not this is a patentable or profitable design, it is a good one and one to be proud of. It may well be worth the effort of doing a patent search (google patents and freepatentsonline.com help the individual inventor get a start) as well as a search of the web for similar designs. (Remember that what matters is that you were first to invent, not first to patent. Even if you were to get a patent, if someone were to demonstrate that the device had been invented 50 years ago they could have your patent overturned... regardless of whether the original inventor had filed for a patent or not. There is a whole section of patent law on the issue of "first to file" vs. "first to invent", but your main concern here is to look for "prior art"... ie. has anyone done this before?) It may also be worth going through the exercise of setting up a small-scale production run, developing a brand name for your product, and marketing your product just as an educational exercise. If it turns a profit... great!

Jason

P.S. Also remember that a patent doesn't prevent someone from using your idea... it merely gives you the right to sue them for damages if they do... and a US patent only protects ideas in the USA. If a US patent is expensive, then protecting your idea world-wide is phenomonally expensive (any idea what it costs to get a patent translated in to Japanese?) That doesn't mean don't "go for it" if you want the experience... in many ways the educational value of developing your design is likely to be far, far greater than the commercial value... just as the educational value of building a FIRST robot is far, far greater than any commercial applications the robots might have.

P.P.S. Should you decide to patent in Canada, I can introduce you to some excellent Canadian patent agents who know a thing or two about FIRST.

Re: pic: Floating Zip Tie Chain Tensioner
 

I hate to be a downer, but this isn't the first time a chain tensioning device like this has been seen in FIRST. I know for a fact that I have seen it on at least 2-3 robots some time ago (like 5-8 years ago). Can't recall who.

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I wouldn't regard your comment as being a "downer". It takes nothing away from the designer, who came up with the idea independently and creatively, to say that other bright and talented people have come up with similar designs. In many ways it is a compliment to the effectiveness of the design.

From a patenting point of view it is also extremely helpful to know exactly what the "prior art" is so that you can describe precisely how a design differs from the prior art and what benefits your design offers. Perhaps this design is simpler to produce, is more reliable, uses less expensive materials, or is easier to adjust. If you don't know about prior art, and sufficiently differentiate your product from what has come before, you may spent a whole lot of time and money getting a patent only to discover that you can't enforce it due to the prior art... so knowing that there are similar designs out there in the public domain is useful for the inventor.

It is extremely difficult to come up with a revolutionary mechanical design. After centuries of designing developments tend to be evolutionary rather than completely new. Often those incremental improvements are quite profitable and quite worth patenting, even though they may only improve performance in some small way. I can see how this design offers some incremental improvements over what I've seen before... and the suggestion to use a hose clamp is possibly another incremental improvement.

Given that the discussion of patents, in the absence of a business plan, is purely academic, knowing that there have been similar desgins in no way marginalizes the "great idea" factor for the designer. So rather than viewing your comments as a downer, I'd view them as evidence that this design is on the right track!

Jason

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I would just like to say thanks to everyone and I am currently talking to AndyMark right now. Hopefully I can get this thing in the market.;)

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Or, for that matter, someone re-drawing the drawing and distributing that.
I know you're in discussions, so I won't comment specifically on that.

One option is to simply give them the idea for free (or some minor consideration, like a 20% discount on your next order). But, that depends on whether they 'want' something like that, or think it will sell. They have some small risk in the cost of manufacturing and inventory, but the risk is small only because the cost is low.

Another alternative is to ask AndyMark to market the product, and you simply supply it. They have little upfront expenses, aside from a web page on their site. You have a small expense, making several samples and a small stock for them to hold on to for orders. And you can make a few dollars for the team, or for yourself.

Just beware that if a LOT of teams want these, you may need to buy materials and make hundreds or even thousands* of them in just a few days - during build season. Getting a whole team to help - who gets the money? - might ease this worry.

I'm not meaning to suggest that AndyMark will do this, I'm just using their name as an example.

*We can only hope!

Don

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So long as it was not an exact replica of the drawing, then there would be no copyright protection. For instance the drawing could be re-drawn to a different scale, show dimensions in different locations, be in first angle rather than third angle projection, have some parts with slightly different dimensions, be a SolidWorks file rather than an Inventor file.... I would even go so far as to say that if the original drawing was drawn exactly to an established standard, then someone could re-draw it to that established standard and have a perfect duplicate without infringing copyright because no creative content went into either drawing. (The creatvity being in the design, not the drawing.) They may even be able to copy the drawing outright, just as they would a table of data, or a bare (non-artistic) chart or graph.

Oh, heck... here's someone who's written it up better and more authoritatively than I http://www.lawmart.com/searches/difference.htm

That is the value of a patent... it truly protects the idea of the design, which is the fundamental part of the invention rather than just an expression of the idea.

Jason

P.S. Good luck with manufacturing and marketing your design. It looks like a design that is extremely well-suited to mass production and once you get your jigs worked out you should be able to churn them out by the hundreds fairly quickly.

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I think it'd be best for him to step back and view this from an economical perspective.

Think about how many of these you need to make, how quickly each one needs to be made, and how much you need to sell them for to break even.

Then think about how many you think you can possibly sell.

If you do the math, I don't think it's a viable investment to try to mass produce these, or even make them on a fairly large scale.

To actually make money you need to be injection molding, not milling these. Injection molding is orders of magnitude more expensive than even the most generous estimate of demand for these.

Given demand, and cost of contracting these out to a machine shop, or time involved in making them yourself, I don't think you can come out on top. Especially given that anyone with a manual mill or even drill press with x+y table can make one of these in about 15 minutes.

Keep in mind that if you choose to make them or have someone else machine them, you have to be able to meet the criteria of a vendor, as well as be capable to potentially ship one to every team in FIRST, if they ordered one, within x time period (I think 5-7 days? can't recall).

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That is why I am talking to Andy Mark, but Cory. Do you think these will sell if they are priced just right???

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Greg & Jason,

Thank you for setting me straight on the copyright issue, and for your thorough discussions.

I've mentioned this discussion to "those I mentioned in my post" who use this practice, but they swear it would hold up in court...oh well...

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Last night I took this into the preliminary CADs my team has for our '09 prototype bases, and we noticed an inherent flaw. Perhaps this is a flaw with all floating tensioners though.

If the two sprockets in the chain run are significantly different relative to their distance apart (e.g. 22-tooth to a 32-tooth, 6" apart) or their axes of rotation are not level with each other (e.g. transmission output shaft is higher than the wheel axle), this tensioner will have a tendendency to "drift" towards the smaller or lower sprocket and stay there without putting any tension on the chain. Is this correct or are we seeing something that isn't really true?

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http://www.snapidle.com/chain_tensioners.htm We used these when I was working with team 507. they worked nicely however since then we have gone to other methods of chain tensioning and may or may not return to these in the future.

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That is true but with this design it is not a problem. On the tops there are spots where you can drill holes and put springs in them so they don't lean one way or the other too much. We had to do this with the original floating tensioners, but they didn't have any spots to drill holes into them (a super hassle and a waste of time).

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Installation of a snap idle : Enough tension need only be applied to take out the slack of the chain. When the drive is in operation the Snapidle® will move back and forth on the chain periodically.
This is a qoute from the snap idle page I referenced earlier. While we did not have such a large difference between our sprockets in use your application may still work due to the snap idle's slight movement. It wouldn't hurt to give it a try. If you do let us know.

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I'll agree with the importance of researching the market as part of a business plan. I would have a hard time seeing how someone could get rich manufacturing these tensioners, however I have no problem believing that they could be manufacutured profitably. Potentially the greatest profit to be had from marketing and manufacturing them is the experience of developing a business plan, refining the production techniques, setting up a business and running it. Even if the business runs at a small loss having that on a resume and that exeperience as part of a professional tool set will be worth thousands of dollars....

But I strongly disagree with the need to have them injection molded in order to turn a profit. The elegance of this particular design is that, as I have mentioned, it can be mass produced in a woodwork shop. The table saw is great for cutting long straight lines and long deep grooves. If you look at the jigs used for creating finger joints that might give you an idea how to make repeated, evenly spaced cuts. Do the cuts on one side of a sheet of HDPE, flip it over, turn it 90 degrees and do the cuts in the opposite direction, then slice it and cut to length to turn out the final product.

This will require a bit of R&D... talking to someone with some fine woodworking experience would be a big help. I would also suggest prototyping the production process using a less expensive material, such as MDF, until the jigs are worked out and acceptable tolerances are achieved.

For an investment of probably less than $200, plus hours and hours of work, it is quite possible to have hundreds of these produced and ready to go very quickly.

I don't think anyone is going to become a millionaire off of this, but the beauty of it is that done properly any financial losses... even if sales are terrible... will be offset by the educational value of going through the entrepreneurial process.

Go for it!

Jason

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Umm, so let me get this straight if you used this as a chain tension device than how long would it last due to the chain grinding against it. Also chain has that special pattern to it with that wouldn't it get locked up on the edges of this device? might want some sort of bearingS to prevent friction but that is just me.

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Its obviously not as efficient as something that rotates, but the plastic used is relatively low friction. I also imagine that the side walls do not hit the side of the chain unless the chain is moving side to side somewhat.

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I would have to see some test data before i make any real judgment on things since the world is full surprises.

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Go to mcmaster.com and type in 5973K1. My idea is based off of this but has a different way of tightening it and is superior in price and quality. Here is my final design of it:



We have been using Mcmaster Carr tensioners and chain does not get locked into the tensioner. UHMW is a very good plastic for this application and the side walls are usually never hit due to the smaller side walls. It is fit for both #25 and #35 chain.

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what is the purpose of the holes on the front and back?

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Say that you want to tension the chain on an arm robot. The chain is going vertically, so you add springs to each side of holes and the tensioner now just hangs: suspended by springs and it still tensions the chain. Also you can attach zip ties or springs to limit how far it floats or if you just want it to stay stationary. Example shown below:


Look at the white tensioner on the lift mechanism, it is suspended by springs and zip ties. The sprockets lifting the arm were of different sizes (a 60 tooth and a 15 tooth), so the tensioner had a tendency of diving down to the smaller sprocket.

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While you can do a lot of engineering and material science related equations, there are a lot of good approximations and rules of thumb that high school students can use on FIRST robots. (Just don't use that practice IRL ;)).

Delrin (and UHMW) are both engineering plastics that have very low friction, and both work great for chain tensioners of various kinds. I prefer Delrin where possible since it machines very nicely (you can mill it really fast too), but it does cost quite a bit.

But if you want proof of plastic chain tensioners, here's a photo from Team 228's 2007 robot.



The white plastic circles are either Delrin (back one) or UHMW (front one). You can also see a third Delrin one on the drivetrain through one of the chassis rail lightening holes in the back. These are really simple ones: plastic rod with an off-center hole. As you rotate it around, it varies the radius; and by cranking down the bolt, it will hold its position.

The Delrin ones held up the entire year (about five competitions and a lot of other random driving) with barely any noticeable surface scratches. The UHMW ones had small (about 1/16") grooves in them from the chain. (There was no particular reason why certain ones were Delrin and others UHMW; they just happened to be whichever our machinist mentor grabbed from the stockpile when making them.)

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Saw this on 1902's '06 bot and chuckled after remembering this thread... apparently they work :)

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I can see why you would want two different sized grooves for the chain to accommodate both #25 and #35 chain, but do you need the different sized grooves for the zip ties, too?

I ask only because it would seem to save a few manufacturing steps to put only a single groove in for each zip tie.

In a similar vein, would it, perhaps, be easier to drill the holes ALL the way through the tensioner? That way you would only need to do two drilling operations rather than four.

You may have a different production path in mind than I envision (as I've mentioned, I see this being an ideal shape to cut on a table saw). For instance with a CNC router, putting in extra grooves would require little in the way of additional manufacturing time. But if you are going to be kicking these out by the hundred using some manual production method, you probably want to include optimizing the production path as part of your design process.

Just a few thoughts that occurred to me without having "seen inside your head" to know why you made these design choices... perhaps I have overlooked something perfectly obvious to you. If so, my apologies.

Jason

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I agree that the 2 grooves for zipties seems unneccesary, and that the holes could go all the way through.

Another thing to consider:
If you were to make 2 different models for two different sizes of chain, it would simplify your design immensely.
I doubt many teams will be switching their tensioners between different sizes of chain very often.
Just because there is demand for more than one chain size, doesn't mean you need to incorporate all sizes into one product

Honestly, I liked your original design better. I think the most recent one you posted looks too complicated and time-consuming to machine.

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Guys, the reason for one tensioner is that we used the #25 Tensioner for both 25 and 35 chain and it worked perfectly. There will be no machining, i am probably going to have a mold for this made. I will probably end up changing the final design after all the comments and after more test runs of this tensioner.

Thanks Cd

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If you are molding it then I would suggest rounding the exterior edges and corners. You might also want to think about putting some draft in to your design, and possibly stamping a product name, website or trademark in to the side as part of the molding process.

I hope that the sales volume is sufficient to cover the up-front cost of the tooling.

Jason

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Unless he's got someone to make him a mold for free, there's just no way he can make a profit off these. The cost of getting a mold made is going to be extremely extremely high if it's being paid for.

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I have a company in mind :D

Re: pic: Floating Zip Tie Chain Tensioner
 

Really cool invention, so this year we can replace the mcmaster carr tensioners. Will buy

Re: pic: Floating Zip Tie Chain Tensioner
 

This product is finally going to be released. Andymark is going to mold and sell this. So thank you everyone that replied and helped me. The final design is not shown.

Thanks CD

Re: pic: Floating Zip Tie Chain Tensioner
 

Looks like AndyMark is stocking these now!

http://andymark.biz/am-0286.html

Re: pic: Floating Zip Tie Chain Tensioner
 

1529 will be sporting these fancy accessories on our 2009 robot. They just came in today and they look awesome.

Re: pic: Floating Zip Tie Chain Tensioner
 

I bought a pair for my control system practice bot. They come in a great package with 2 rubber bands and 3 zip ties.

The robot was originally built for a college capstone project. The bot worked great except the chains would fall off. I haven't had a chance to try the tensioners yet.