07-10-2008 10:08

Richard Wallace

Re: pic: Andymark's New Product

WOOT!

07-10-2008 10:18

Elgin Clock

Re: pic: Andymark's New Product

I understood the original concept, but what are the curved up tabs sticking out the sides for in this design?
I will refrain from my next comment about those tabs before I hear their purpose, since I assume they have one.

07-10-2008 10:33

Alan Anderson

Re: pic: Andymark's New Product

I don't know if this is the intent, but they seem perfect as hooks for a rubber band on each side of the tensioner pairs.

07-10-2008 10:37

Andy Baker

Re: pic: Andymark's New Product

Bingo... rubber bands or o-rings will fit on those hooks.

We hope to get this completed by December 1.

Thanks to RC and team 1323 for letting us partner with them on this project.

Andy B.

07-10-2008 14:50

Akash Rastogi

Re: pic: Andymark's New Product

Congrats on a huge accomplishment RC.

Can't wait to see what else you come up with in the future.

07-10-2008 15:33

vivek16

Re: pic: Andymark's New Product

Nice, I know we're going to buy a few. They seem like a very cheap and effective way of tensioning chains.

07-10-2008 15:45

AndyB

Re: pic: Andymark's New Product

These gonna be available for both #25 and #35 hopefully? I'm assuming these will be molded. Has a material been picked yet? Polycarb? Delrin?

Question mark?

07-10-2008 15:55

Alan Anderson

Re: pic: Andymark's New Product

It's designed to work with either size. Check out the dual-step profile of the chain groove.

07-10-2008 15:58

gorrilla

Re: pic: Andymark's New Product

wow thats great now i just need to come up with something

any idea on price?

07-10-2008 17:55

R.C.

Re: pic: Andymark's New Product

The material will be UHMW and it will be molded. I think the price will be between $10-15 and I don't know for sure. The price will probably change.

07-10-2008 18:10

vivek16

Re: pic: Andymark's New Product

So is that for a pair? A single one? two pairs?

thanks, Vivek

07-10-2008 18:11

R.C.

Re: pic: Andymark's New Product

That is a pair sir.

07-10-2008 19:01

gorrilla

Re: pic: Andymark's New Product

a pair as in two or a pair as in two sets of two

07-10-2008 19:03

AdamHeard

Re: pic: Andymark's New Product

a pair as in two of what is pictured; enough to tension one run of chain.

08-10-2008 01:02

Gary.C

Re: pic: Andymark's New Product

Very Nice RC, now only if I could come up with something. Lol.

08-10-2008 12:04

Dan Petrovic

Re: pic: Andymark's New Product

Certainly cheaper than tensioners that you can get from McMaster-Carr... that's a huge bonus.

08-10-2008 12:15

FoleyEngineer

Re: pic: Andymark's New Product

We'll definitely be buying them. Only worry that comes to mind is if there's enough material to take the wear and tear without "wearing through"? The tensioners we made ourselves out of Delrin probably had a 1/2" of solid backing and I'll bet we wore through 1/8" of it. Looks like there might only be 1/8" there, but it's hard to tell w/o dimensions. Have you done any testing on wear?

Thanks,
John

08-10-2008 12:35

R.C.

Re: pic: Andymark's New Product

UHMW is a harder plastic than delrin. Our Mcmaster Carr ones only wore 3/16th's and we used them for almost 2 years.

08-10-2008 12:46

Greg Needel

Re: pic: Andymark's New Product

not in all cases. standard uhmw is around 66 shore D while Delrin is around 86 shore D

Since these are both plastics which can contain glass filling, other materials, recycled plastic it is not wise to make generalizations about materials. Especally in this case where you didn't state the exact material which these are molded and the exact type of delrin they used.


On another note, I am not sure that hardness is the correct measure for effective chain tensioners. I would think it has to do with the lubricity of the material and the ductility. While hardness probably comes into play (ie why gum rubber wouldn't be a good tensioner) It is not the only (or possibly the main one) which needs to be considered.

08-10-2008 14:10

MikeDubreuil

Re: pic: Andymark's New Product

I'd like to make a suggestion for this thread and the AndyMark website...

I have been following the development of this product since the first CAD drawings were posted on CD. Now, I think I'm a fairly smart guy... college educated and a pretty good software engineer.... it took me a very long time to realize these would be used as a pair and tie wrapped together. Now I realize why everyone thought the idea was so beautiful in its simplicity.

Now for the suggestion... could you show a picture of it used on a robot? I think that would help people (maybe I'm the only one) understand how to use it and why it's so effective.

08-10-2008 14:29

Elgin Clock

Re: pic: Andymark's New Product

Ok. I can safely comment about those curved features now.

In our typical chassis designs, we run our chain in a very tight area between 2 metal plates. I'm concerned in our design (and in similar one's I've seen) that those tabs are sticking out way too much to be effective & not get snagged on those plates, or anything mounted inside those plates. (Bronze bushings, spacers, screw heads, etc...)

We had our frame spaced so tightly one year in terms of area between plates, that a rushed replacement socket head cap screw (rather than the original flat head screw) actually popped the chain right at the link in the finals match of a competition.

I love this design, but I'm just saying that if we were to use these, we would more than likely just use zip-ties, not use the rubber bands or o-rings (which I think will wear out even more quickly over a competition anyways and require more maintenence - even more so than the blocks themselves with the concerns Greg N. posted) & we would probably cut or shave those curved tabs right off.

Just a thought from someone with bad experience with a hardware vs chain matchup in a real world design application.

Of course, your results may vary.

08-10-2008 14:46

Zflash

Re: pic: Andymark's New Product

http://www.snapidle.com/

This website with a similar product has a picture that shows the concept. However for what it matters I endorse the AM product, might as well support a fellow FIRSTer!

08-10-2008 15:01

Richard Wallace

Re: pic: Andymark's New Product

The Snapidle Mini appears to be the same kind of tensioner sold by McMaster-Carr (5973K1 or 5973K2, depending on the chain size). Those sell for about $30 each.

08-10-2008 20:44

R.C.

Re: pic: Andymark's New Product

As for the picture of this thing in action, I will take one tomorrow and upload it and why it is so effective:

-Lightweight
-Cheap
-No maintenance
-Easy Removal (We wasted so much time taking the snap ones on and off).
-Can be left floating or can be made stationary
-No lubrication



The zipties don't wear really, you could ideally go 7-8 matches without even worrying about the zip ties. As long as you cut the ends of the zip ties off. If the frame is really too tight. We used only one of the blocks then. We mounted it in between and made it stationary. If you upload a pic of your frame. I could give you solution. We had this problem when we were using the mcmaster carr ones 3 years ago.

08-10-2008 20:55

Zflash

Re: pic: Andymark's New Product

Having used the snap idle version I know how those are pulled together in order to keep the chain properly tensioned. With this you either use ty wraps or o-rings. My question is how easy is it to get enough tension on the ty-wrap without having to use a ty-wrap gun since most chassis do not have the room for it.

08-10-2008 20:59

Aren_Hill

Re: pic: Andymark's New Product

I like the simplicity, but it puts too many things out of control for me, such as the slack between the two sides when the sprockets change directions would be undesireable in my opinion. Our method was swiped from 118 with nice tensioners that just involve tweaking a screw a little tighter. And the chain loops were stable and not whipping around all over the place.

the main reason they wouldn't work to well in our situation is the proximity to victors... so no whippage room was available, kinda cause the swerve drive. We may use them elsewhere though it looks like a solid product, congrats

efficiency wise ball bearing idler sprockets and pulling the drive/driven sprockets to adjust the chain wins vs sliding on plastic

08-10-2008 23:13

R.C.

Re: pic: Andymark's New Product

You could always tension these with a hose clamp if you wanted to.

09-10-2008 18:15

DonRotolo

Re: pic: Andymark's New Product

Now how cool is that? Can they mold your initials on it just for bragging rights?
Ah, so that's why our tensioners kept wearing out...

Seriously: I would have some concerns about stress on those hooks breaking them off. I'd want a bigger fillet, or even a small gusset, where the hook meets the body. (Then again, it's just a CAD drawing, Andy or Mark probably saw what I am seeing already, before committing to a mould).

Don

09-10-2008 20:49

ParkerF

Re: pic: Andymark's New Product

This product looks great. I'm glad AndyMark was able to market these items at a cheaper price than what was on the market before. Tumbleweed used a set of those Snapidle Minis on the chain to the 'front' wheel. We went through these unfortunately quickly with the amount of driving the bots went through with practice and competition. The straps for the set we used would become easily worn and annoying to deal with. In order to take them off you actually had to take one side of the tensioner apart. I think zip-ties will be much more cost efficient for teams, along with just plain easier on the pit crews. I hope to see these in action some time this season!

10-10-2008 09:27

Josh Goodman

Re: pic: Andymark's New Product

Very nice RC, congrats on this accomplishment! The only thing that can make it better is taking suggestions from other FIRSTers!