Go to Post And those who DO know won't talk, even for Krispy Kremes. - DonRotolo [more]
Home
Go Back   Chief Delphi > ChiefDelphi.com Website > Extra Discussion
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Reply
Thread Tools Rate Thread Display Modes
  #1   Spotlight this post!  
Unread 27-12-2011, 14:12
shai's Avatar
shai shai is offline
Team Captain
FRC #3083 (Artemis)
 
Join Date: Jan 2011
Rookie Year: 2009
Location: Israel
Posts: 22
shai has a spectacular aura aboutshai has a spectacular aura aboutshai has a spectacular aura about
pic: Artemis 3083 West Coast

Reply With Quote
  #2   Spotlight this post!  
Unread 27-12-2011, 14:13
MattC9's Avatar
MattC9 MattC9 is offline
Registered User
no team
Team Role: Alumni
 
Join Date: Nov 2010
Rookie Year: 2009
Location: Texas
Posts: 435
MattC9 has a spectacular aura aboutMattC9 has a spectacular aura aboutMattC9 has a spectacular aura about
Re: pic: Artemis 3083 West Coast

All I can say that someone is on the right track!
Reply With Quote
  #3   Spotlight this post!  
Unread 27-12-2011, 14:23
Mk.32's Avatar
Mk.32 Mk.32 is offline
Registered User
AKA: Mark
FRC #2485 (W.A.R. Lords)
Team Role: Engineer
 
Join Date: Jan 2011
Rookie Year: 2011
Location: San Diego
Posts: 770
Mk.32 has much to be proud ofMk.32 has much to be proud ofMk.32 has much to be proud ofMk.32 has much to be proud ofMk.32 has much to be proud ofMk.32 has much to be proud ofMk.32 has much to be proud ofMk.32 has much to be proud ofMk.32 has much to be proud ofMk.32 has much to be proud of
Re: pic: Artemis 3083 West Coast

It looks like the chain would interfere on the cross beans in your design?
Also for the bumper mounts I would look at 973's design, almost the same thing but a bit simpler.
And for mounting the gearbox, I would recommend using the KOP hex beams to brace them, or put in another set of bolts to hold it to the chassis.


But overall a great start, can't wait to see more.
__________________
Engineering mentor: Team 2485: WARLords 2013-

Team President: Team 3647 2010-2013

Last edited by Mk.32 : 27-12-2011 at 15:01.
Reply With Quote
  #4   Spotlight this post!  
Unread 27-12-2011, 15:48
Cory's Avatar
Cory Cory is offline
Registered User
AKA: Cory McBride
FRC #0254 (The Cheesy Poofs)
Team Role: Engineer
 
Join Date: May 2002
Rookie Year: 2001
Location: Redwood City, CA
Posts: 6,812
Cory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond reputeCory has a reputation beyond repute
Send a message via AIM to Cory
Re: pic: Artemis 3083 West Coast

What made you choose magnesium?

It's about 40% less dense than aluminum, but it's yield strength is nearly 4 times lower than 6061 and it's ultimate strength is 60% lower.
__________________
2001-2004: Team 100
2006-Present: Team 254
Reply With Quote
  #5   Spotlight this post!  
Unread 27-12-2011, 16:59
Tristan Lall's Avatar
Tristan Lall Tristan Lall is offline
Registered User
FRC #0188 (Woburn Robotics)
 
Join Date: Aug 2001
Rookie Year: 1999
Location: Toronto, ON
Posts: 2,484
Tristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond reputeTristan Lall has a reputation beyond repute
Re: pic: Artemis 3083 West Coast

Magnesium? Which alloy?

Also, do you take precautions against fire when machining? Magnesium shavings—at least in pure form (I'm not sure about wrought alloys)—are flammable. Most shops wouldn't have a class D fire extinguisher lying around.
Reply With Quote
  #6   Spotlight this post!  
Unread 27-12-2011, 17:38
shai's Avatar
shai shai is offline
Team Captain
FRC #3083 (Artemis)
 
Join Date: Jan 2011
Rookie Year: 2009
Location: Israel
Posts: 22
shai has a spectacular aura aboutshai has a spectacular aura aboutshai has a spectacular aura about
Re: pic: Artemis 3083 West Coast

Thank you all for your replies!

Quote:
Originally Posted by Mk.32 View Post
It looks like the chain would interfere on the cross beans in your design?
And for mounting the gearbox, I would recommend using the KOP hex beams to brace them, or put in another set of bolts to hold it to the chassis.
Thank you very much, those are some important tips. Here is a quick update:



I looked at team 973's bumper mounts but couldn't find major differences. How would you improve the design?


Quote:
Originally Posted by Cory View Post
What made you choose magnesium?
It's about 40% less dense than aluminum, but it's yield strength is nearly 4 times lower than 6061 and it's ultimate strength is 60% lower.
We are using magnesium profiles as the main frame component for most of our robot for three years and it does a great work every time. When comparing it to our practice robots, that are usually made from aluminum, the magnesium parts seem to stand in impacts (that you can except for an FRC robot) just as well.


Quote:
Originally Posted by Tristan Lall View Post
Magnesium? Which alloy?
Also, do you take precautions against fire when machining? Magnesium shavings—at least in pure form (I'm not sure about wrought alloys)—are flammable. Most shops wouldn't have a class D fire extinguisher lying around.
I am not sure which of the alloys we use, but I'll make sure to find out. I do know, however, that this is the same alloy that is used to make the frame for Alubin's bicycles, in case that this gives you some useful information about it.
Magnesium alloy is much more stable than pure magnesium, and is similar to aluminum when machining. However it does require different treatment in some cases.
Thank you for your concern
Reply With Quote
  #7   Spotlight this post!  
Unread 27-12-2011, 18:16
Mk.32's Avatar
Mk.32 Mk.32 is offline
Registered User
AKA: Mark
FRC #2485 (W.A.R. Lords)
Team Role: Engineer
 
Join Date: Jan 2011
Rookie Year: 2011
Location: San Diego
Posts: 770
Mk.32 has much to be proud ofMk.32 has much to be proud ofMk.32 has much to be proud ofMk.32 has much to be proud ofMk.32 has much to be proud ofMk.32 has much to be proud ofMk.32 has much to be proud ofMk.32 has much to be proud ofMk.32 has much to be proud ofMk.32 has much to be proud of
Re: pic: Artemis 3083 West Coast

Quote:
Originally Posted by shai View Post
Thank you all for your replies!

I looked at team 973's bumper mounts but couldn't find major differences. How would you improve the design?
It seems your design means that to switch bumpers one would have to undo 8 or more bolts. Having had a similar system our first robot, I can say it wasn't fun and we promptly changed it to something much faster.

Also, just wondering, how does one go about welding magnesium alloy? Same process as alum or steel?
__________________
Engineering mentor: Team 2485: WARLords 2013-

Team President: Team 3647 2010-2013
Reply With Quote
  #8   Spotlight this post!  
Unread 27-12-2011, 18:52
apalrd's Avatar
apalrd apalrd is offline
More Torque!
AKA: Andrew Palardy (Most people call me Palardy)
VRC #3333
Team Role: College Student
 
Join Date: Mar 2009
Rookie Year: 2009
Location: Auburn Hills, MI
Posts: 1,347
apalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond reputeapalrd has a reputation beyond repute
Re: pic: Artemis 3083 West Coast

Quote:
Originally Posted by Mk.32 View Post
It seems your design means that to switch bumpers one would have to undo 8 or more bolts. Having had a similar system our first robot, I can say it wasn't fun and we promptly changed it to something much faster.
With four individual bumpers (not a one-piece bumper), you need at least 8 fasteners for a solid connection. We had 10 this year, plus flanges that hooked into slots in the bumper supports.

The better solution is to either not have four individual bumpers, or use fitted bumper covers. We did the second this year, and it worked very well.
__________________
Kettering University - Computer Engineering
Kettering Motorsports
Williams International - Commercial Engines - Controls and Accessories
FRC 33 - The Killer Bees - 2009-2012 Student, 2013-2014 Advisor
VEX IQ 3333 - The Bumble Bees - 2014+ Mentor

"Sometimes, the elegant implementation is a function. Not a method. Not a class. Not a framework. Just a function." ~ John Carmack
Reply With Quote
  #9   Spotlight this post!  
Unread 27-12-2011, 21:06
AustinSchuh AustinSchuh is offline
Registered User
FRC #0971 (Spartan Robotics) #254 (The Cheesy Poofs)
Team Role: Engineer
 
Join Date: Feb 2005
Rookie Year: 1999
Location: Los Altos, CA
Posts: 803
AustinSchuh has a reputation beyond reputeAustinSchuh has a reputation beyond reputeAustinSchuh has a reputation beyond reputeAustinSchuh has a reputation beyond reputeAustinSchuh has a reputation beyond reputeAustinSchuh has a reputation beyond reputeAustinSchuh has a reputation beyond reputeAustinSchuh has a reputation beyond reputeAustinSchuh has a reputation beyond reputeAustinSchuh has a reputation beyond reputeAustinSchuh has a reputation beyond repute
Re: pic: Artemis 3083 West Coast

Consider moving your corner brackets on top of the frame, and pop-riveting them in. This will make sure your frame is all aligned before it is sent to your welder, and make it easier to weld.
Reply With Quote
  #10   Spotlight this post!  
Unread 28-12-2011, 05:05
shai's Avatar
shai shai is offline
Team Captain
FRC #3083 (Artemis)
 
Join Date: Jan 2011
Rookie Year: 2009
Location: Israel
Posts: 22
shai has a spectacular aura aboutshai has a spectacular aura aboutshai has a spectacular aura about
Re: pic: Artemis 3083 West Coast

Quote:
Originally Posted by Mk.32 View Post
It seems your design means that to switch bumpers one would have to undo 8 or more bolts. Having had a similar system our first robot, I can say it wasn't fun and we promptly changed it to something much faster.
Quote:
Originally Posted by apalrd View Post
With four individual bumpers (not a one-piece bumper), you need at least 8 fasteners for a solid connection. We had 10 this year, plus flanges that hooked into slots in the bumper supports.
The better solution is to either not have four individual bumpers, or use fitted bumper covers. We did the second this year, and it worked very well.
Actually, our bumpers mounts are designed so it can be used with no screws at all, or with 8 M4 screws. In order to lock the bumpers in place we insert a screw or a pin through the bumper mount and the frame, so it is fast to insert and prevent the bumper from moving.
We also use a bumper with changeable color as seen in this video by team 1937: http://www.youtube.com/watch?v=7PVkTPe7XIc , so we don't have to disassemble the bumper in order to get ready for a match.

Quote:
Originally Posted by Mk.32 View Post
Also, just wondering, how does one go about welding magnesium alloy? Same process as alum or steel?
We use gas tungsten arc welding for the magnesium profiles, so it is similar to aluminum welding, although it does require some special equipment and experience.

Quote:
Originally Posted by AustinSchuh View Post
Consider moving your corner brackets on top of the frame, and pop-riveting them in. This will make sure your frame is all aligned before it is sent to your welder, and make it easier to weld.
This is a good idea, I think we will do that.

Thanks you all
Reply With Quote
  #11   Spotlight this post!  
Unread 28-12-2011, 10:22
mott's Avatar
mott mott is offline
Registered User
AKA: Mike Ott
FRC #1619 (Up-A-Creek Robotics)
Team Role: Mentor
 
Join Date: Jan 2010
Rookie Year: 2008
Location: Niwot, CO
Posts: 105
mott is on a distinguished road
Re: pic: Artemis 3083 West Coast

Just a quick follow-up on the suggestion about the corner braces assisting with the welding...

As the mentor who handles most of the welding for team 1730, I would NOT recommend riveting the corner brackets into place before welding the frame. Doing so would create 2 "three-wall" pockets at each corner of the frame that are very difficult to weld (especially without actually welding the corner gussets in with the 2 frame members)!

I'm sure every welder out there has their own preferences but my suggestion on "helping out" the welder on a frame like this would be to make 2 "jig bar spacers" that are the exact length as the space you want between the left and right frame rails. Your 4 perimeter frame members can then be clamped together with 2 bar clamps in each direction (using your jig bars near each end of the side rails) to ensure you are parallel left to right. Then, with everything clamped together, you can verify you're square and weld.

Other Hints:

If possible, keep all your clamps on the same side of the frame, this allows getting a big framing square on the other side without obstruction (and allows easier corner-to-corner measurements as well.

Depending on your eventual frame design, these "jig bar spacers" can eventually become inner cross-members of the frame itself. Once your perimeter frame rails are welded, reposition the jig bars to where you'd like the cross-members and weld them into place as well.

If you want to use corner braces in addition to the welding (we actually haven't on Team Driven's frames) you should consider NOT making them triangles as you're probably better off without the 90 degree corner on the gusset where it would interfere with the face-welded joint of the 2 frame members.
Reply With Quote
  #12   Spotlight this post!  
Unread 31-12-2011, 21:33
shirraj's Avatar
shirraj shirraj is offline
Registered User
AKA: Shir Rajuan
FRC #2630 (Thunderbolts)
Team Role: Mechanical
 
Join Date: Feb 2011
Rookie Year: 2011
Location: Israel
Posts: 8
shirraj is an unknown quantity at this point
Re: pic: Artemis 3083 West Coast

Shay did you considered using 8 wheels? we did last year with the same 4" wheels and it worked really good. you can also look at 2010 robot and see the same idea of 8 wheels the different is the size.
the main though was to do the 2 middle wheels in each side a little bit lower. this gives you easier turns & in case of big bumpers (2010) with the right size of wheels its will be helpful. the problem of making this idea with 3 wheels is the robot is unstable.. can I ask why did you go with 6 wheels & 2 gearbox?
and I guess that the 4" comes to give a lower gravity center?
to see the robots I talked about you can go on our site under History and choose the year
emekhefer2630.com
__________________
"FRC is the way - person is the goal"

Emek Hefer Thunderbolts - love at FIRST sight XD
Reply With Quote
  #13   Spotlight this post!  
Unread 01-01-2012, 13:52
shai's Avatar
shai shai is offline
Team Captain
FRC #3083 (Artemis)
 
Join Date: Jan 2011
Rookie Year: 2009
Location: Israel
Posts: 22
shai has a spectacular aura aboutshai has a spectacular aura aboutshai has a spectacular aura about
Re: pic: Artemis 3083 West Coast

Mott, thank you very much for the great tips. I will make sure to work together with our welders when finalizing the design.

Shir, I remember your drive train and it did worked very well.
Our center wheels are indeed lowered.
A 6WD is not necessarily less stable than an 8WD. This is because a design that places the robot's center of gravity away from the middle will result in much less swinging over the center wheel. A robot with eight wheels might do better in those terms, but we find the loss of weight and improved simplicity of a 6WD more important to us.
Our decision to use 4" wheels is based on a few reasons; one of them is to allow us to have a lower CoG.
Reply With Quote
  #14   Spotlight this post!  
Unread 01-01-2012, 16:28
shirraj's Avatar
shirraj shirraj is offline
Registered User
AKA: Shir Rajuan
FRC #2630 (Thunderbolts)
Team Role: Mechanical
 
Join Date: Feb 2011
Rookie Year: 2011
Location: Israel
Posts: 8
shirraj is an unknown quantity at this point
Re: pic: Artemis 3083 West Coast

Quote:
Originally Posted by shai View Post
Shir, I remember your drive train and it did worked very well.
Our center wheels are indeed lowered.
A 6WD is not necessarily less stable than an 8WD. This is because a design that places the robot's center of gravity away from the middle will result in much less swinging over the center wheel. A robot with eight wheels might do better in those terms, but we find the loss of weight and improved simplicity of a 6WD more important to us.
Our decision to use 4" wheels is based on a few reasons; one of them is to allow us to have a lower CoG.
2011 was good but our telescope and gripper was way heavier then planed and all though we used 4" wheels the CoG was too high. this is why it was swinging over.. but also from my team's experience 6WD doesn't do the work as well as 8WD and its working differently - the 6WD is all the time on the middle wheels & either of the front or back wheels, the 8WD is all the time on the 2 middle wheels just while needed the other 4 wheels come to help.
anyhow see you at the Kick-off in a week!!
and here starts the end of our life
__________________
"FRC is the way - person is the goal"

Emek Hefer Thunderbolts - love at FIRST sight XD
Reply With Quote
Reply


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 02:07.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi