OCCRA
Go to Post Canada has five regional events now. Canada. - Nick Lawrence [more]
Home
Go Back   Chief Delphi > Technical > Technical 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 07-21-2018, 08:11 PM
mikets's Avatar
mikets mikets is offline
Software Engineer
FRC #0492 (Titan Robotics Club)
Team Role: Mentor
 
Join Date: Jan 2010
Rookie Year: 2008
Location: Bellevue, WA
Posts: 799
mikets is a name known to allmikets is a name known to allmikets is a name known to allmikets is a name known to allmikets is a name known to allmikets is a name known to all
Mouting a work piece on an Omio CNC router

Our team recently acquired an Omio CNC router. We have almost zero experience using CNC routers. While it is relatively simple, for example, to mount a piece of aluminum sheet on the machine and cut a gear box plate, it is something else to mount a box beam to the CNC router and have holes cut in the precision of 1/1000th of an inch (or whatever precision the CNC machine supports). In cutting a part out of an aluminum sheet, the raw stock piece doesn't need to be mounted/aligned on the machine very precisely. However, if the holes must be cut very precisely on a location of the stock piece, precision in mounting the stock piece becomes a big issue. For example, let's say we are fabricating an Andymark nanotube (http://www.andymark.com/NanoTube-p/am-2200.htm) using a box beam. We need to cut holes on both sides of the box beam. Since the cutter bits on an Omio router are not long enough to "cut through" both the top and bottom surfaces, one must finish cutting one side, flip the box beam around and cut the other side. When flipping the box beam, if there is a slight misalignment in mounting, the holes will not be aligned perfectly. A slight misalignment may cause the axle to be not perfectly orthogonal to the surfaces. This could cause uneven stress on the motors/bearings. And making it even worse, you need to fabricate two of these nanotubes. If the left and right tubes are not perfectly identical, the robot may not run straight.

One of our mentors is experience in manual milling. Our manual mill can mill with a precision of 1/1000th of an inch and he has set up very precise stoppers on the milling vise so when a box beam is clamped, it is guaranteed one corner is at (0.0, 0.0) origin. Then he can crank the vise with high precision digital readout to the exact location he needs to drill/cut down to 1/1000th inch precision. In addition, the manual mill has long cutting bits that can cut through both the top and bottom surfaces of the box beam so alignment on both surfaces is not a problem.

How can we achieve the same precision with the Omio CNC router? I am sure many teams have solved this problem, we just need to learn the process. We have thought of a few possible set ups but would love to hear what other teams do on this issue.
__________________
Reply With Quote
  #2   Spotlight this post!  
Unread 07-21-2018, 08:19 PM
sanddrag sanddrag is offline
On to my 18th year in FRC
FRC #0696 (Circuit Breakers)
Team Role: Teacher
 
Join Date: Jul 2002
Rookie Year: 2002
Location: Glendale, CA
Posts: 8,825
sanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond repute
Re: Mouting a work piece on an Omio CNC router

You can mount some strips of MDF to the machine, then cut it with the machine to make a corner square/fence that is square to the machine. Or you can get some kind of square, maybe like a framing square and indicate it into square, and then rest your box tube against that. Rockler has lots of nice clamps and things you may want to check out.
__________________
Teacher/Engineer/Machinist - Team 696 Circuit Breakers, 2011 - Present
Mentor/Engineer/Machinist, Team 968 RAWC, 2007-2010
Technical Mentor, Team 696 Circuit Breakers, 2005-2007
Student Mechanical Leader and Driver, Team 696 Circuit Breakers, 2002-2004
Reply With Quote
  #3   Spotlight this post!  
Unread 07-21-2018, 09:07 PM
cpapplefamily's Avatar
cpapplefamily cpapplefamily is offline
Registered User
FRC #3244 (Granite City Gearheads)
Team Role: Mentor
 
Join Date: May 2015
Rookie Year: 2015
Location: Minnesota
Posts: 745
cpapplefamily is a splendid one to beholdcpapplefamily is a splendid one to beholdcpapplefamily is a splendid one to beholdcpapplefamily is a splendid one to beholdcpapplefamily is a splendid one to beholdcpapplefamily is a splendid one to beholdcpapplefamily is a splendid one to behold
Re: Mouting a work piece on an Omio CNC router

Yes i was thinking a fence milled to square the part in the machine. Then after milling the first side in the aluminium. Remove the party and mill the same features into the waist board. When you flip the part key off these features with a pair of bearings. This only works if the holes are centered on the 3" side and they should be. If they are not you may have to create a job to index the part to a known spot.
__________________
It makes sense in my mind.



Reply With Quote
  #4   Spotlight this post!  
Unread 07-21-2018, 09:47 PM
juju_beans's Avatar
juju_beans juju_beans is offline
Registered User
FRC #3647 (Millennium Falcons)
Team Role: CAD
 
Join Date: Jan 2016
Rookie Year: 2016
Location: California
Posts: 98
juju_beans is a name known to alljuju_beans is a name known to alljuju_beans is a name known to alljuju_beans is a name known to alljuju_beans is a name known to alljuju_beans is a name known to all
Re: Mouting a work piece on an Omio CNC router

You can make a vise jig like my team did (inspired from 1678). Heres a photo.
__________________
It worked in the CAD!

CNC Router and HSMWorks Series
Reply With Quote
  #5   Spotlight this post!  
Unread 07-22-2018, 07:19 AM
DonRotolo's Avatar
DonRotolo DonRotolo is offline
Broke a hundred!
FRC #0832
Team Role: Mentor
 
Join Date: Jan 2005
Rookie Year: 2005
Location: Atlanta GA
Posts: 7,372
DonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond repute
Re: Mouting a work piece on an Omio CNC router

As with anything, there are many ways.

Even if your machine could cut completely through to the bottom surface of the box, it will likely be incorrect because of the bit deflection: The tip of the bit deflects sideways, affecting the cut.

If your machine has "auto homing" which repeatably brings the cutter to a known position (such as 0,0), use that. If this can be added - almost certainly it can - make that a priority. Similarly, get an auto-Z setter if possible, although not as essential since you are cutting through.

Make a fixture to hold the box, fasten that firmly to the machine, and use that. Think of a 1" deep slot machined into a 1.5" deep piece of plywood, perfectly aligned with the machine (have the machine make it!). Put the box in there, hold it down*, and if the machine X,Y is zeroed you know exactly where the work piece is...including when you flip it over to machine the bottom.

*Hold down: The open ends are a good place to start, clamp the bottom surface down. If necessary, a cross-strap can hold the middle down.
__________________

*All comments are mine and do not represent my place of employment*
Reply With Quote
  #6   Spotlight this post!  
Unread 07-22-2018, 11:28 AM
Oblarg Oblarg is offline
Registered User
AKA: Eli Barnett
FRC #0449 (The Blair Robot Project)
Team Role: Mentor
 
Join Date: Mar 2009
Rookie Year: 2008
Location: Philadelphia, PA
Posts: 1,900
Oblarg has a reputation beyond reputeOblarg has a reputation beyond reputeOblarg has a reputation beyond reputeOblarg has a reputation beyond reputeOblarg has a reputation beyond reputeOblarg has a reputation beyond reputeOblarg has a reputation beyond reputeOblarg has a reputation beyond reputeOblarg has a reputation beyond reputeOblarg has a reputation beyond reputeOblarg has a reputation beyond repute
Re: Mouting a work piece on an Omio CNC router

We have a permanent tube jig set up with three of these vises (we should probably add one or two more):

https://littlemachineshop.com/produc...y=196325691 4

The difficult part is getting it trammed properly, so that it is parallel to the machine axes. You can do this with an edgefinder, like we did, but it's tedious - the easiest way is to use a dial indicator. Put an end stop on one of the vises at the end of the jig, and then set your zero relative to the jig, and you're good to go.
__________________
"Mmmmm, chain grease and aluminum shavings..."
"The breakfast of champions!"

Member, FRC Team 449: 2007-2010
Drive Mechanics Lead, FRC Team 449: 2009-2010
Alumnus/Technical Mentor, FRC Team 449: 2010-Present
Lead Technical Mentor, FRC Team 4464: 2012-2015
Technical Mentor, FRC Team 5830: 2015-2016


FRC Drivetrain Characterization
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 03:57 PM.

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


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi