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-   -   233 telescoping arms how do they work? (http://www.chiefdelphi.com/forums/showthread.php?t=116765)

smart1 08-05-2013 16:01

233 telescoping arms how do they work?
 
i have seen pictures but i still can't figure how they work. I want to know how to make one this summer. any pics or cad would be great.

ehfeinberg 08-05-2013 16:17

Re: 233 telescoping arms how do they work?
 
Although I can't vouch for the pink team, on FRC-Designs team 75 has posted a CAD of their 2011 robot with a telescoping arm.

48 also seems to have a telescoping arm, but theirs uses a pneumatic cylinder instead of a lead screw for the telescoping motion.

I would still like to hear how 233 (and 2016) did their telescoping arms.

Nemo 08-05-2013 16:21

Re: 233 telescoping arms how do they work?
 
I had a chance to ask 254 a bunch of questions about theirs. Thanks to 254 for having a model out for fan boys and girls to look at and answering lots of questions. I was trying to explain some of it to people, but if somebody has a nice picture of a 233 or 254 arm, that make it a lot easier for us to develop something of our own. Figuring out a good telescoping arm that we're capable of fabricating is high on our list of generally useful things we want to learn how to do.

ehfeinberg 08-05-2013 16:32

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by Nemo (Post 1273391)
I had a chance to ask 254 a bunch of questions about theirs. Thanks to 254 for having a model out for fan boys and girls to look at and answering lots of questions. I was trying to explain some of it to people, but if somebody has a nice picture of a 233 or 254 arm, that make it a lot easier for us to develop something of our own. Figuring out a good telescoping arm that we're capable of fabricating is high on our list of generally useful things we want to learn how to do.

I don't believe 254 ever made a telescoping arm. Wicked fast elevator, yes. But telescoping arm, I believe not.

About 233, not a picture but a video.
Here is a picture, but you cant really see anything close up...

Thad House 08-05-2013 16:36

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by ehfeinberg (Post 1273395)
I don't believe 254 ever made a telescoping arm. Wicked fast elevator, yes. But telescoping arm, I believe not.

About 233, not a picture but a video.
Here is a picture, but you cant really see anything close up...

254 used 2 233 style telescoping arms for their 30 point climber this year, and had a spare one for people to look at at championships this year. It was really cool, but I could not explain it even if i tried.

smart1 08-05-2013 16:37

Re: 233 telescoping arms how do they work?
 
they had 2 this year on their climber.

R1ffSurf3r 08-05-2013 16:50

Re: 233 telescoping arms how do they work?
 
I'm on sketchy Internet in Germany right now so I can't post any pics, but the arm is relatively simple. Our best example would definitely be 2011, which in my opinion is the best robot 233 has ever produced.

We use three different sizes of box tube, with fancy bearing blocks holding it all together. The telescoping action is powered by a motor at the bottom and chain.

The most complicated pieces are probably the bearing blocks. I believe they are cut with a wire edm and milled, and everything moves smoothly with rollers. Its hard to explain without pics, but there are blocks on the inside of the tops of the tubes, and the outsides of the bottom of the tubes. If you find a good pic this will make a lot more sense. We keep about 6 inches of overlap when fully extended. In 2010 we tried out using waterjetted delrin in place of these rollers and blocks, and honestly it just sucked so don't bother.

Some other cool features of the arm include dual constant force springs that entirely counterbalance the telescoping portion, and a less slick system of surgical tube to balance the rotation. There are also delrin springs that act as shock absorbers when the arm retracts and slams closed. For rotation the whole arm sits in split bearings. But honestly the coolest addition to the 2011 iteration is how the rotation was powered. Instead of using chain like usual, there was one giant wire edm cut gear that fit directly to the arm.

Now all of these features aren't entirely necessary for an effective arm, but are the result of continuous improvement over the years. Effective programming and intuitive driver control should be considered the highest priorities in my opinion.

coalhot 08-05-2013 18:19

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by bliz213 (Post 1269774)
My team came to Champs this year with the goal to scout robots, sadly not to compete. A small crew of my team members and I went to close to 70 teams and took close up pictures of different their robots.

https://www.dropbox.com/sh/3fxabc28nvvkcr8/A2tQie9tgK

We spent Friday and Saturday running from pit to pit to get all of these pictures. There are close to 1000 pictures neatly organized by team number.

Hope those teams that couldn't make it can enjoy these pictures.

From one of the post photos threads. Look at 254's set, there are a few really good shots of the arm, and the bearing assemblies it rides on.

smart1 08-05-2013 18:40

Re: 233 telescoping arms how do they work?
 
thanks for the pics

Mike Marandola 08-05-2013 19:42

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by coalhot (Post 1273423)
From one of the post photos threads. Look at 254's set, there are a few really good shots of the arm, and the bearing assemblies it rides on.

This is awesome. I wasn't able to check out some robots up close at worlds so this is great.

Tom Line 08-05-2013 21:12

Re: 233 telescoping arms how do they work?
 
I understand the structure - the roller bearings and ball bearings etc.

How exactly are the belts driven and cascaded through the system? I'm not seeing how they are connected or function.

coalhot 08-05-2013 23:25

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by Tom Line (Post 1273471)
I understand the structure - the roller bearings and ball bearings etc.

How exactly are the belts driven and cascaded through the system? I'm not seeing how they are connected or function.

I'm not sure. The closest photo I could find is this.

Maybe someone from 254 or 233 could chime in, or you could spend about an hour looking at old 233 posts. I remember coming across a thread where 233 explained how their arm extended and operated (2007 version). Also, 254 talked about how theirs worked in the 7 second climb revel thread.

If I remember correctly (and don't quote me on this), 233 used a spring extend, while 254 didn't.

ablatner 08-05-2013 23:36

Re: 233 telescoping arms how do they work?
 
I remember it's a single belt going all the way through that's fixed to the stage that extends the most. I could figure out the belt path and pulleys from memory, but I'd have to spend some time drawing it out.

DampRobot 09-05-2013 00:28

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by Tom Line (Post 1273471)
I understand the structure - the roller bearings and ball bearings etc.

How exactly are the belts driven and cascaded through the system? I'm not seeing how they are connected or function.

Imagine a single stage system for simplicity. The belt is pulled by a pulley at the bottom of the "zeroth" stage, and runs over a idler at the top of the zeroth stage. The belt then connects to the bottom of the first moving stage. When the stages are together, the length of the belt is ~2*stage length. When the first stage is extended, the length of the belt is ~1*stage length. Retraction works in the opposite way.

A two stage system works similarly, but with the bottom and top of the first stage being idlers, and the belt being connected to the bottom of the second stage.

I believe there's a pretty good paper on CD-Media which explain all of this in more detail.

coalhot 09-05-2013 00:37

Re: 233 telescoping arms how do they work?
 
Also, specifics on this thread link

Spending a few minutes searching can get you a long ways along...

Travis Schuh 09-05-2013 01:02

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by coalhot (Post 1273423)
From one of the post photos threads. Look at 254's set, there are a few really good shots of the arm, and the bearing assemblies it rides on.

That exposed bearing assembly pictured in the referenced photos is for the simple level 1 hanger (hook on the end of a piston), which is entirely separate from the 233 climber arms. I am pretty sure that the 233 climber arms use bearings for only the front-back sides and use plastic on the other two sides.

-Travis

Jeffy 09-05-2013 01:46

Re: 233 telescoping arms how do they work?
 
Links that helped me solve this problem:

Take a long stare at a few of these and you will figure out how they work.

https://www.dropbox.com/sh/3fxabc28nvvkcr8/A2tQie9tgK
specifically: https://www.dropbox.com/sh/3fxabc28n...f:DSC_0149.JPG

Also: http://www.chiefdelphi.com/forums/sh...ng+a+clim ber

Good luck!

JesseK 09-05-2013 09:01

Re: 233 telescoping arms how do they work?
 
2 Attachment(s)
233's 2011 Arm was a beauty to behold. Good luck to anyone who wants to make one :D

akoscielski3 09-05-2013 10:11

Re: 233 telescoping arms how do they work?
 
Can we please get a CAD model of those? Or extremely detailed pictures? It's so hard to see what is going on in there :P

Doug G 09-05-2013 11:13

Re: 233 telescoping arms how do they work?
 
Why is that when I look at 254's machine to see how they did something, I come away with more questions than answers... that machine and its mechanisms are so condensed, it's just insane.

Triple B 09-05-2013 16:00

Re: 233 telescoping arms how do they work?
 
I can only speak for the 233 arm on this topic. First off, a gearbox is attatched to the outside of the largest box (4d0 x 4d0 x d125 al box) at the bottom of the tower. It has a shaft that transfers power to a sprocket on the inside of the box. At the top of the box is an idler sprocket which is also the tensioner for this chain. We will call this chain 1. Chain 1 is attatched to the outside of the next box (2d5 x 2d5 x d125 al box) thru what I call the "chain anchor". The motor/gearbox drives this stage in and out directly.
The gearbox has a 10 turn pot attatched which controls the limits and also the PID control for ramping up and down the power as the tower nears its limits at each end of its travel. Now here is where it gets a little tricky, the opposite side if the 2d5 box has a shaft in the bottom with a sporcket on the inside and the outside, this is what drives the final stage of the tower. It also has an idler at the top which also acts as the tensioner for these 2 chains.
The chains both have a "chain anchor". The chain on the inside of 2d5 box is attached to the bottom of the final stage (1d0 x 1d0 x d125 al box). The chain on the outside of the box is attatched to the inside of the 4do box. The key is that the anchors are on opposite sides of the chain, this allows the second stage to use the anchor to drive the chain which extends the final stage at the same time. This is a very lengthy post and I may not of explained the subject completely but it has started an open line of communication. Ask any questions you may have and i can explain why Charlie did not like the delrin bearing blocks from 2k10.

Mike D "233 for life"

ASmith1675 09-05-2013 16:36

Re: 233 telescoping arms how do they work?
 
Awesome stuff. Thanks for all the info about these mechanisms.

When we've built these cascaded telescoping lifts/arms in the past, we've used a winch system for the first stage. What I'm having trouble wrapping my mind around with both of 233's and 254's telescoping arms is where the extra chain/timing belt, goes when these mechanisms are extended. Or are just the cascaded sections using the timing belt/chain?

Always trying to come up with better solutions, and these are the type of mechanisms we're all striving to make (in some small way).

Pat Fairbank 09-05-2013 17:43

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by Smitty1707 (Post 1273716)
What I'm having trouble wrapping my mind around with both of 233's and 254's telescoping arms is where the extra chain/timing belt, goes when these mechanisms are extended.

In this year's arms, the other end of the belt comes off the bottom pulley and then goes back up inside the bottom of 1x1 tube (the last stage), where it is clamped.

This section of belt (from the pulley to the bottom of the last stage) is what takes all the tension when the arm is being retracted. This way, the force exerted by the weight of the robot while climbing is just transmitted through the (large) bearings and shaft supporting the bottom pulley, and not on any of the tiny ones where the belt doubles back on itself.

The beauty of using a telescoping arm for hanging, in my opinion, is that there are no moments exerted on any of the stages during retraction.

CENTURION 09-05-2013 18:41

Re: 233 telescoping arms how do they work?
 
If I'm reading this thread right, the arms are basically a condensed version of this right?

Lil' Lavery 09-05-2013 19:05

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by CENTURION (Post 1273747)
If I'm reading this thread right, the arms are basically a condensed version of this right?

That's similar to 254's arm, in that it is a multi-stage, continuous lift.

If I understand MikeD's post correctly, 233's multi-stage arms are essentially cascaded lifts, but the second stage does not return to the original power source (and is instead driven "passively" by a sprocket that is turned as the first stage extends).

The key difference for both arms is that all the stages are nested within each other, which presents numerous challenges and advantages.

CENTURION 09-05-2013 19:54

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by Lil' Lavery (Post 1273754)
That's similar to 254's arm, in that it is a multi-stage, continuous lift.

If I understand MikeD's post correctly, 233's multi-stage arms are essentially cascaded lifts, but the second stage does not return to the original power source (and is instead driven "passively" by a sprocket that is turned as the first stage extends).

The key difference for both arms is that all the stages are nested within each other, which presents numerous challenges and advantages.

Ah, okay, yeah we used a cascade like the 233 one you describe in 2011 to raise/lower tubes.

Yeah, the nesting sounds very hard to do. Maybe if I get bored over the summer I'll CAD up something :D

Tom Line 09-05-2013 21:05

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by CENTURION (Post 1273764)
Ah, okay, yeah we used a cascade like the 233 one you describe in 2011 to raise/lower tubes.

Yeah, the nesting sounds very hard to do. Maybe if I get bored over the summer I'll CAD up something :D

The nesting is only really difficult if you want to put it into a very small package. Pink's arm and Poof's variation show true engineering elegance in packaging, from the wide rollers to the usage of belt (low profile) to the threading of the linear springs through the system.

The question that you'll also have to answer is the orientation of the constant force springs. Do you use them to extend the arm and only pull one way with your motors? Do you use to retract the arm so they help you lift the robot, but power the arm in both directions?

It's a really awesome design that I wanted to understand to put it in our 'toolbox'.

MichaelBick 10-05-2013 04:14

Re: 233 telescoping arms how do they work?
 
If somebody is still having a hard time understanding how the poof's arm works, I took many pictures which are posted here: https://drive.google.com/folderview?...&usp=sha ring

Triple B 10-05-2013 09:34

Re: 233 telescoping arms how do they work?
 
In our application we use the constant force springs to assist the extend function only. It offsets the weight of the manipulator on the end of the tower/elevator. The motor/motors have plenty of power for lifting the robot and we use a locking type ratchet to hold the weight up after the buzzer but the idea of having the motor/motors stalled out to hold position while the tower is extended is not, in my opinion, a healthy one. This year we did an elevator and used constant force springs to assist the elevator in lifting our shooter deck, it weighed in at about 18lbs. I find it ironic that we did an elevator and the Poofs did telescoping towers this year

Mike D "233 for life"

Nemo 10-05-2013 09:43

Re: 233 telescoping arms how do they work?
 
To the people who have posted in this thread: I just want you to know that after the school year ends, I'm going to devour the information in this thread, including both the pictures and written explanations. I am looking forward to trying to figure out the guts of one of these arms and working with some students to create a model of something we could build. Thanks very much for all of the posts.

Steven Donow 10-05-2013 09:52

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by Nemo (Post 1273874)
To the people who have posted in this thread: I just want you to know that after the school year ends, I'm going to devour the information in this thread, including both the pictures and written explanations. I am looking forward to trying to figure out the guts of one of these arms and working with some students to create a model of something we could build. Thanks very much for all of the posts.

If only it were possible for Pink or 254 to send everyone here an arm :D

Lil' Lavery 10-05-2013 10:15

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by DevenStonow (Post 1273877)
If only it were possible for Pink or 254 to send everyone here an arm :D

I think the postal service might question why disembodied limbs are being shipped around the country.

Triple B 10-05-2013 10:55

Re: 233 telescoping arms how do they work?
 
good one Sean, and you are correct on your earlier post about the passive drive of the third stage on pinks tower.

roystur44 10-05-2013 11:08

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by smart1 (Post 1273383)
i have seen pictures but i still can't figure how they work. I want to know how to make one this summer. any pics or cad would be great.

Take a look at how 1986 did their arm. They used heavy duty drawer slides and a cascaded cable and pulley system. It was simple, elegant, easy to manufacture and did the job.

smart1 10-05-2013 13:24

Re: 233 telescoping arms how do they work?
 
we have done many lift's with bosch 20 series with custom sliders and cable but that has it's limitations, mainly strength and weight.

M. Mellott 10-05-2013 17:33

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by Nemo (Post 1273874)
To the people who have posted in this thread: I just want you to know that after the school year ends, I'm going to devour the information in this thread, including both the pictures and written explanations. I am looking forward to trying to figure out the guts of one of these arms and working with some students to create a model of something we could build. Thanks very much for all of the posts.


Seconded. These are some great idea to digest! Many thanks as well!

craigboez 11-05-2013 20:13

Quote:

Originally Posted by Triple B (Post 1273873)
In our application we use the constant force springs to assist the extend function only.

Mike D "233 for life"

Would you mind elaborating on which constant force springs you use?

EDIT: I ask because I'm only familiar with the coil style constant force springs and if you used those I'm curious how they were implemented.

Chinmay 11-05-2013 22:17

Re: 233 telescoping arms how do they work?
 
Try looking up negator spring or constant force spring motor. It's a really nicely packed solution to the counterbalance problem. Ill update this when I'm at a computer with some links Ect.

craigboez 12-05-2013 01:14

Re: 233 telescoping arms how do they work?
 
1 Attachment(s)
Quote:

Originally Posted by Triple B (Post 1273697)
I can only speak for the 233 arm on this topic. First off, a gearbox is attatched to the outside of the largest box (4d0 x 4d0 x d125 al box) at the bottom of the tower. It has a shaft that transfers power to a sprocket on the inside of the box. At the top of the box is an idler sprocket which is also the tensioner for this chain. We will call this chain 1. Chain 1 is attatched to the outside of the next box (2d5 x 2d5 x d125 al box) thru what I call the "chain anchor". The motor/gearbox drives this stage in and out directly.
The gearbox has a 10 turn pot attatched which controls the limits and also the PID control for ramping up and down the power as the tower nears its limits at each end of its travel. Now here is where it gets a little tricky, the opposite side if the 2d5 box has a shaft in the bottom with a sporcket on the inside and the outside, this is what drives the final stage of the tower. It also has an idler at the top which also acts as the tensioner for these 2 chains.
The chains both have a "chain anchor". The chain on the inside of 2d5 box is attached to the bottom of the final stage (1d0 x 1d0 x d125 al box). The chain on the outside of the box is attatched to the inside of the 4do box. The key is that the anchors are on opposite sides of the chain, this allows the second stage to use the anchor to drive the chain which extends the final stage at the same time. This is a very lengthy post and I may not of explained the subject completely but it has started an open line of communication. Ask any questions you may have and i can explain why Charlie did not like the delrin bearing blocks from 2k10.

Mike D "233 for life"

After some analysis, this is my understanding of what Mike describes.

EDIT: would someone familiar with the 254 system we willing to describe or diagram that system? From looking at all the pictures, I believe they use a different concept.

R1ffSurf3r 12-05-2013 06:48

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by craigboez (Post 1274179)
Would you mind elaborating on which constant force springs you use?

EDIT: I ask because I'm only familiar with the coil style constant force springs and if you used those I'm curious how they were implemented.

look at post 18, and the second picture

smart1 13-05-2013 21:19

Re: 233 telescoping arms how do they work?
 
Thanks for all of the helpful insight.

craigboez 17-05-2013 15:53

Re: 233 telescoping arms how do they work?
 
1 Attachment(s)
After looking through the pictures referenced earlier in the thread, I was able to better understand the 254 telescopic arm. It is conceptually very different from the 233 arm.
  • 254 used a single piece of belt routed continuously through the assembly and then pinned to the final stage at each end of the belt. See attached for a diagram.
  • 233 used two loops of chain, one to drive the first stage and then in a cascading fashion used the first stage to drive the second stage. See my previous post 39 for a diagram.
Both elegant solutions to a similar problem, and as you can see from the pics, the hardest part of building one of these is in the packaging.

We attempted to build a nylon strap driven arm, similar in concept to the 254 design, and found it very difficult to get all the rollers, idler pulleys, and pieces of slippery UHMW from colliding with each other. In the end we ran out of time, kept the first stage, and just implemented a first level hanger.

The devil is definitely in the details with these mechanisms.

Travis Covington 17-05-2013 16:18

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by craigboez (Post 1275615)
After looking through the pictures referenced earlier in the thread, I was able to better understand the 254 telescopic arm. It is conceptually very different from the 233 arm.
  • 254 used a single piece of belt routed continuously through the assembly and then pinned to the final stage at each end of the belt. See attached for a diagram.
  • 233 used two loops of chain, one to drive the first stage and then in a cascading fashion used the first stage to drive the second stage. See my previous post 39 for a diagram.


The devil is definitely in the details with these mechanisms.

This is correct. Thanks for illustrating this for others.

smart1 17-05-2013 21:58

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by craigboez (Post 1275615)
After looking through the pictures referenced earlier in the thread, I was able to better understand the 254 telescopic arm. It is conceptually very different from the 233 arm.
  • 254 used a single piece of belt routed continuously through the assembly and then pinned to the final stage at each end of the belt. See attached for a diagram.
  • 233 used two loops of chain, one to drive the first stage and then in a cascading fashion used the first stage to drive the second stage. See my previous post 39 for a diagram.
Both elegant solutions to a similar problem, and as you can see from the pics, the hardest part of building one of these is in the packaging.

We attempted to build a nylon strap driven arm, similar in concept to the 254 design, and found it very difficult to get all the rollers, idler pulleys, and pieces of slippery UHMW from colliding with each other. In the end we ran out of time, kept the first stage, and just implemented a first level hanger.

The devil is definitely in the details with these mechanisms.

Thanks again.

fr05ty27355 21-10-2013 11:37

Re: 233 telescoping arms how do they work?
 
What did 254 and 233 do to pin the chain/belt to a stage? I'm wondering if they put bolts through the chain/belt, pinched the chain/belt against a toothed surface, or did something else. I'm guessing they might have had different methods since 254 used a belt and 233 used chain.

George C 21-10-2013 13:50

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by fr05ty27355 (Post 1297650)
What did 254 and 233 do to pin the chain/belt to a stage? I'm wondering if they put bolts through the chain/belt, pinched the chain/belt against a toothed surface, or did something else. I'm guessing they might have had different methods since 254 used a belt and 233 used chain.

We did something similar for a two-stage cascading mechanism driven by a Gates belt. We were able to saw and file a piece of aluminum to match the Gates tooth profile. The block covered about 6 teeth and we avoided putting holes through the belt. Worked perfectly on the second try.

Nuttyman54 21-10-2013 14:26

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by George C (Post 1297673)
We did something similar for a two-stage cascading mechanism driven by a Gates belt. We were able to saw and file a piece of aluminum to match the Gates tooth profile. The block covered about 6 teeth and we avoided putting holes through the belt. Worked perfectly on the second try.

971 did a similar attachment method with a machined block to match the belt tooth profile for their elevator in 2011.

For #25 chain, you can fit #4 screws through the gaps between the rollers to fix it to something, although I don't know if this is how 233 does it or not. Another method is to drill a hole in the fixed structure that one end of a masterlink fits through.

thefro526 21-10-2013 14:32

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by Nuttyman54 (Post 1297681)

For #25 chain, you can fit #4 screws through the gaps between the rollers to fix it to something, although I don't know if this is how 233 does it or not. Another method is to drill a hole in the fixed structure that one end of a masterlink fits through.

I've also used #4 Screws to fix #25 chain before, it works just fine when done right but can be a bit tricky considering the size of both the chain and the screws.

233, in 2011 at least, machines a part that appears to 'look' like a #25 chain link at either end and uses that to fix the chain to the stages. Here's a few pictures on their flickr.

http://www.flickr.com/photos/thepinkteam/5787028180/

http://www.flickr.com/photos/thepinkteam/5787033770/

http://www.flickr.com/photos/thepink...n/photostream/

BurkeHalderman 21-10-2013 15:03

Re: 233 telescoping arms how do they work?
 
Has anyone tried using these to attach chain? Specifically the K-1 style connector.

http://www.mcmaster.com/#roller-chai...hments/=p1acmb

Seems like an easier option than machining an attachment for the chain.

Nuttyman54 21-10-2013 15:17

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by BurkeHalderman (Post 1297695)
Has anyone tried using these to attach chain? Specifically the K-1 style connector.

http://www.mcmaster.com/#roller-chai...hments/=p1acmb

Seems like an easier option than machining an attachment for the chain.

I'm sure it's been done, but #35 chain is the smallest size that you can get those style links in. Most of these style elevators have space and weight at a premium, so #25 chain is preferred.

yash101 21-10-2013 21:55

Re: 233 telescoping arms how do they work?
 
Maybe fill it up with pressurized air (like a piston out) to make it longer, and have a spring retract it. Maybe that will work for light/medium loads

Jared 21-10-2013 22:12

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by yash101 (Post 1297782)
Maybe fill it up with pressurized air (like a piston out) to make it longer, and have a spring retract it. Maybe that will work for light/medium loads

If you could get the thing air tight (which would be really tough) I don't think it would be legal per the 2013 rules. I know a team wanted to fill a balloon with air from the compressor, but they weren't allowed to.

EricH 21-10-2013 22:14

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by yash101 (Post 1297782)
Maybe fill it up with pressurized air (like a piston out) to make it longer, and have a spring retract it. Maybe that will work for light/medium loads

Except that if you don't do that with a COTS pneumatic cylinder, you're in violation of the rules (specifically R76). I don't see the ban on non-COTS pneumatic items going away anytime within the next decade, if not century. On top of the large volume of air you'd need for any reasonable extension length, and the fun of fitting at least one cylinder that long inside the arm, which make for a very nasty engineering challenge between them...

Brandon_L 22-10-2013 00:45

Re: 233 telescoping arms how do they work?
 
Am I the only one that likes the lead screw method?

Its beautiful.

If you ask, they're more then happy to share some drawings on that arm. I have them saved somewhere. To me, it seems a little more simple and solid then all these chain runs. Cons being I'm not sure how you'd have multiple stages.

DampRobot 22-10-2013 01:22

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by Brandon_L (Post 1297804)
Am I the only one that likes the lead screw method?

Its beautiful.

If you ask, they're more then happy to share some drawings on that arm. I have them saved somewhere. To me, it seems a little more simple and solid then all these chain runs. Cons being I'm not sure how you'd have multiple stages.

Very cool! I love the robot, I'm really surprised not to have heard of it before.

I suppose another disadvantage of the leadscrew would be it's expense and inefficiency. Of course, it does look like a very elegant solution in that situation.

Jared 22-10-2013 19:15

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by Brandon_L (Post 1297804)
Am I the only one that likes the lead screw method?

Its beautiful.

If you ask, they're more then happy to share some drawings on that arm. I have them saved somewhere. To me, it seems a little more simple and solid then all these chain runs. Cons being I'm not sure how you'd have multiple stages.

If you use lead screws right, they are a really solid and durable solution, but may be overkill for some applications. This year, our climber used two lead screws, and although it was heavy, we never had a single mechanical problem with the lead screws, which was the only part of any robot we've ever built that was this reliable. We fell off of the top of the pyramid, and from the second level, and our climbing device wasn't damaged at all.

MichaelBick 28-10-2013 04:19

Re: 233 telescoping arms how do they work?
 
Stuff got moved around in my google drive, and the previous album link now does not work. I got a PM to repost the link so here it is: https://drive.google.com/folderview?...&usp=sha ring

I will have to try to find a more permanent solution for the future.


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