o-ring belts
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Bill Weiler
Mar 14, 2013, 3:49:22 PM3/14/13
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I am trying to find o-ring belts for my Nanosumo robot. Researching online, it seems urethane is the best material for belts. However, I have been unsuccessful finding urethane o-rings around an inch I.D. What would be really great is a kit, so I could get the perfect size and not have to make a approximation when I order. Can anyone give me advice on where to get this? Thanks.
Bill W.
Bill W.
Ralph Gnauck
Mar 14, 2013, 4:54:07 PM3/14/13
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Have you looked at McMaster-Carr
Ralph
From: Bill Weiler <bill...@gmail.com>
To: hbrob...@googlegroups.com
Sent: Thu, March 14, 2013 12:49:26 PM
Subject: [HBRobotics] o-ring belts
I am trying to find o-ring belts for my Nanosumo robot. Researching online, it seems urethane is the best material for belts. However, I have been unsuccessful finding urethane o-rings around an inch I.D. What would be really great is a kit, so I could get the perfect size and not have to make a approximation when I order. Can anyone give me advice on where to get this? Thanks.
Bill W.
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Bill Weiler
Mar 14, 2013, 5:07:27 PM3/14/13
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I checked them out but I need belts 1" long but their minimum is 4". This is the same problem I have with other sites.
Bill W.
Bill W.
Bill Weiler
Mar 14, 2013, 5:11:31 PM3/14/13
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Maybe I could order 4" neoprene belts,cut them to size, and glue them together with gasket sealer?
On Thu, Mar 14, 2013 at 1:54 PM, Ralph Gnauck <ralp...@pacbell.net> wrote:
Ralph Gnauck
Mar 14, 2013, 5:34:08 PM3/14/13
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Check the 'High performance' belts, looks like they go from 1" and up in 1" increments.
Ralph
Sent: Thu, March 14, 2013 2:11:35 PM
Subject: Re: [HBRobotics] o-ring belts
Subject: Re: [HBRobotics] o-ring belts
Bill Weiler
Mar 14, 2013, 5:35:36 PM3/14/13
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But they specify a 3/4" minimum pulley diameter. My motor pulley is less than 2mm.
Bill W.
Bill W.
Chuck Nolan
Mar 14, 2013, 6:17:13 PM3/14/13
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G'Day Bill,
Don't waste your time with McMaster Carr or Grainger for this kind of item.
ERIKS Seals and Plastics, Inc.
http://www.eriksusa.com/resources/o-ring-technical-handbook/15.pdf
Ph: 408-988-2291
They normally have a $50.00 per order minimum and a $5.00 per line item minimum. I suggested to their inside sales person that they might consider waving to minimum, for students from Carnegie Melon or the robotics club. It never hurts to ask.
Miniature o'rings are regularly used in designing material transports, where they are used like tires on pulley like rims.
The smallest available seems to be 1/32" ID x 3/32" OD x 1/32 tire thickness.
The closest to 2-mm seems to be 5/64" ID x 13/64" OD x 1/16" tire thickness.
There is a 3/4" ID x 7/8" OD x 1/16" Thickness, which would require a pulley with a 1/32" deep 1/16" radius groove for a 50% - 50% retention.
If for some reason you can't buy just a small number, you could try Motion Industries in Santa Clara that sells small quantities of items to plant engineers and maintenance people.
Many of the hardware stores like Orchard Supply have hardware cabinets where they stock a few common sizes of bearings, o'rings, and other mechanical parts.
Repair parts, such as rollers for sliding doors, and other home repair items can be converted to wheels and other small parts for building mechanical prototypes or hobby projects.
Regards,
Chuck Nolan
Don't waste your time with McMaster Carr or Grainger for this kind of item.
ERIKS Seals and Plastics, Inc.
http://www.eriksusa.com/resources/o-ring-technical-handbook/15.pdf
Ph: 408-988-2291
They normally have a $50.00 per order minimum and a $5.00 per line item minimum. I suggested to their inside sales person that they might consider waving to minimum, for students from Carnegie Melon or the robotics club. It never hurts to ask.
Miniature o'rings are regularly used in designing material transports, where they are used like tires on pulley like rims.
The smallest available seems to be 1/32" ID x 3/32" OD x 1/32 tire thickness.
The closest to 2-mm seems to be 5/64" ID x 13/64" OD x 1/16" tire thickness.
There is a 3/4" ID x 7/8" OD x 1/16" Thickness, which would require a pulley with a 1/32" deep 1/16" radius groove for a 50% - 50% retention.
If for some reason you can't buy just a small number, you could try Motion Industries in Santa Clara that sells small quantities of items to plant engineers and maintenance people.
Many of the hardware stores like Orchard Supply have hardware cabinets where they stock a few common sizes of bearings, o'rings, and other mechanical parts.
Repair parts, such as rollers for sliding doors, and other home repair items can be converted to wheels and other small parts for building mechanical prototypes or hobby projects.
Regards,
Chuck Nolan
Sent: Thu, March 14, 2013 2:35:41 PM
robotMaker
Mar 14, 2013, 6:57:34 PM3/14/13
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This is what I would probably do, from a hardware store, or other local supplier, I would find urethane hose, such as surgical hose, and cut the rings from that. Or I would try using caulking silicone and make my own rings. Then I can also control the thickness as well. You did not mention the thickness or your requirement. I've made O rings before, I used urethane molding compound from Tap plastics. First I made a straight rod of from the urethane then cut to size and used superglue to make the ring.
Also www.smallparts.com might have it. They once had a "sumo bot" picture on the front cover of their catalog, implying that they had the small parts to make one. I think that SmallParts is now owned by Amazon.
Cesar
Also www.smallparts.com might have it. They once had a "sumo bot" picture on the front cover of their catalog, implying that they had the small parts to make one. I think that SmallParts is now owned by Amazon.
Cesar
Sent: Thursday, March 14, 2013 1:49 PM
Subject: [HBRobotics] o-ring belts
Subject: [HBRobotics] o-ring belts
I am trying to find o-ring belts for my Nanosumo robot. Researching online, it seems urethane is the best material for belts. However, I have been unsuccessful finding urethane o-rings around an inch I.D. What would be really great is a kit, so I could get the perfect size and not have to make a approximation when I order. Can anyone give me advice on where to get this? Thanks.
Bill W.
Bill W.
Srihari Yamanoor
Mar 14, 2013, 7:02:33 PM3/14/13
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Cesar's advice should work. If you are willing to pay a little more, you could get them 3D printed (I believe a start up in Oakland does various shore hardness rubbers, I could dig up the name as I used them before) or contact Apple Rubber - they make custom O-rings and may do Urethane.
SmallParts is now Amazon Supply Inc.
Sincerely,
Srihari
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Bill Weiler
Mar 14, 2013, 7:31:28 PM3/14/13
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This advise is great. Small parts has many sizes. Part of my problem is my design. I am using the Solarbotics pager motor w/pulley and 11mm pulleys from Tamiya pulley kit from Pololu. I am using the 11mm pulleys as wheels and pulleys in one. I don't know how far the o-ring will rest in "V" of the 11mm pulley (it's a 4mm "V"). So I don't know what length the o-rings need to be.This also affects my ground clearance which is another critical parameter. Also, I don't know how soft or flexible I need the o-rings to be or how tight they should be. To be ready in time for Robogames, I have to order the o-rings before the bot is assembled. I may get a rough estimate of length and order several o-rings around that range. Going to Orchard supply and getting some o-rings of a close diameter would also help with the measure/estimate.
Bill W.
Bill W.
robotMaker
Mar 15, 2013, 2:12:45 PM3/15/13
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I understand what you're trying to do, and you're practically describing the sumo-bot on the SmallParts catalog. SmallParts no longer publishes the catalog.
I bought this kit from Harbor Freight some time ago, very cheap. It has 382 O-rings, an assortment of 30 sizes.
http://www.harborfreight.com/382-piece-o-ring-assortment-67554.html
To get the approximate size as close as possible to the real thing, I would try using rubber bands of different sizes and shapes, and use superglue to adjust the sizes. It's too bad that you don't have your bot assembled as yet, it would make things easier.
Cesar
This is the bot (MARV Jr. from Sandia Labs) that was on the catalog:
http://www.time.com/time/specials/packages/article/0,28804,1936165_1936255_1936636,00.html
I bought this kit from Harbor Freight some time ago, very cheap. It has 382 O-rings, an assortment of 30 sizes.
http://www.harborfreight.com/382-piece-o-ring-assortment-67554.html
To get the approximate size as close as possible to the real thing, I would try using rubber bands of different sizes and shapes, and use superglue to adjust the sizes. It's too bad that you don't have your bot assembled as yet, it would make things easier.
Cesar
This is the bot (MARV Jr. from Sandia Labs) that was on the catalog:
http://www.time.com/time/specials/packages/article/0,28804,1936165_1936255_1936636,00.html
Sent: Thursday, March 14, 2013 5:31 PM
Subject: Re: [HBRobotics] o-ring belts
robotMaker
Mar 15, 2013, 2:17:46 PM3/15/13
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Sent: Thursday, March 14, 2013 5:31 PM
Subject: Re: [HBRobotics] o-ring belts
Subject: Re: [HBRobotics] o-ring belts
Bill Weiler
Mar 15, 2013, 2:25:42 PM3/15/13
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Here is a video showing exactly what I mean. I can see the results from last year at Robogames and the top finishers were from other countries. Kind of clues me in the competition is going to be tough.
http://www.youtube.com/watch?v=PudhKY_5oG8
Bill W.
http://www.youtube.com/watch?v=PudhKY_5oG8
Bill W.
Chuck Nolan
Mar 15, 2013, 2:50:22 PM3/15/13
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G'Day All,
There is a big difference between the world of computer aided design and finite element analysis and the creation of demonstration devices or fully custom items.
The human mind has great capabilities in simulation, like the way we find a rhythm when driving nails or pressing the brake pedal in our vehicles. You can develop the ability to simulate mechanical systems and to visualize places where force concentrates or friction produces wear. This is very much like the way many of you learned to do simple math in your head. Nicola Tesla claimed that it was this ability that made it possible for him to design the Niagara project and other things.
Conceptual engineering, and in the real world most equipment engineering, is based on experience, comparison, and maybe some manufacturer's recommendations.
With regards to the selection of o'ring tires, the typical o'ring that comes in a o'ring kit at an auto supply store will usually work fine. Softer o'rings would increase drive system friction and tend to come off of rims in high torque applications. In some designs the surface requires more contact area. In this case a timing belt may be a better choice, tending to perform like the track on a tractor.
If the surface is not flat, then a trailing arm suspension, where each tire is at the end of a floating arm and is driven by its own drive belt can provide a very effective design. Think of this like the rear wheel on a high quality motorcycle.
In competitions or applications that present threats, the drive system needs to be behind flexible energy absorbing bumpers. The drive system it self can even be designed to absorb impact by slipping in reverse, or by spinning away from an impact, rather than taking the hit head on. This again is conceptual engineering.
Regards,
Chuck
There is a big difference between the world of computer aided design and finite element analysis and the creation of demonstration devices or fully custom items.
The human mind has great capabilities in simulation, like the way we find a rhythm when driving nails or pressing the brake pedal in our vehicles. You can develop the ability to simulate mechanical systems and to visualize places where force concentrates or friction produces wear. This is very much like the way many of you learned to do simple math in your head. Nicola Tesla claimed that it was this ability that made it possible for him to design the Niagara project and other things.
Conceptual engineering, and in the real world most equipment engineering, is based on experience, comparison, and maybe some manufacturer's recommendations.
With regards to the selection of o'ring tires, the typical o'ring that comes in a o'ring kit at an auto supply store will usually work fine. Softer o'rings would increase drive system friction and tend to come off of rims in high torque applications. In some designs the surface requires more contact area. In this case a timing belt may be a better choice, tending to perform like the track on a tractor.
If the surface is not flat, then a trailing arm suspension, where each tire is at the end of a floating arm and is driven by its own drive belt can provide a very effective design. Think of this like the rear wheel on a high quality motorcycle.
In competitions or applications that present threats, the drive system needs to be behind flexible energy absorbing bumpers. The drive system it self can even be designed to absorb impact by slipping in reverse, or by spinning away from an impact, rather than taking the hit head on. This again is conceptual engineering.
Regards,
Chuck
Sent: Fri, March 15, 2013 11:25:46 AM
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