Go to Post The FIRST program is different. It has a different purpose. It isn't superficial, it's results are long term and lasting. I hope that FIRST is still on message. - JohnBoucher [more]
Home
Go Back   Chief Delphi > Technical > Motors
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Closed Thread
Thread Tools Rate Thread Display Modes
  #1   Spotlight this post!  
Unread 04-02-2002, 01:26
Travis Covington's Avatar Unsung FIRST Hero
Travis Covington Travis Covington is offline
Engineering Mentor
FRC #0254
Team Role: Engineer
 
Join Date: Oct 2001
Rookie Year: 1998
Location: San Jose, CA
Posts: 574
Travis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond repute
Send a message via AIM to Travis Covington
using set screw or dowel pin/pin to hold on drill motor coupler thinggy

i was wondering what would be best to attatch the drill motor extension shaft to the motor shaft with (the design is similar to team 45'sa dual gear switching design)

should we pin it using a dowel pin, regular pin, set screw *yuck* or regular thru screw?

thanks
__________________
-Travis Covington

2008-2017 - Engineering Mentor of Team 254
2001-2008 - Engineering Mentor of Team 968
1998-2001 - Mechanical Director/Driver/Member of Team 115
  #2   Spotlight this post!  
Unread 04-02-2002, 03:02
Ken Leung's Avatar Unsung FIRST Hero
Ken Leung Ken Leung is offline
Dare to Live!
FRC #0115 (Monta Vista Robotics Team)
Team Role: Mentor
 
Join Date: May 2001
Rookie Year: 1999
Location: Palo Alto, California
Posts: 2,390
Ken Leung has a reputation beyond reputeKen Leung has a reputation beyond reputeKen Leung has a reputation beyond reputeKen Leung has a reputation beyond reputeKen Leung has a reputation beyond reputeKen Leung has a reputation beyond reputeKen Leung has a reputation beyond reputeKen Leung has a reputation beyond reputeKen Leung has a reputation beyond reputeKen Leung has a reputation beyond reputeKen Leung has a reputation beyond repute
Send a message via AIM to Ken Leung
socket head screw

I know the technokats used to use a coupling to go around the drill motor shaft, and drill and tap through it, and screw in a #8-32 socket head screw. The coupling/extended shaft should be good enough to hold the drilled motor shaft together. And this screw should provide enough strength to hold the motor shaft and the extended shaft together.

That is not exactly the drill motor extension shaft the technokat's have on their motor mount design, but the concept is the same. A pilot hole on the coupling/extension shaft will make the drilling much easier, because you know you are drilling the dead center.

It might be a little challenging to line up the pilot hole to be straight, but you can always just put a long pin with exact size as the hole, use the drill chuck to grab onto that, lock down the vice around that shaft and lock down the vice, and then pull away the pin and replace with a drill bit. Then you know you are drilling the exact center and the right direction.

If you don't have the pilot hole on the coupling/extension shaft, I suggest you drill one first before you start drilling through motor output shaft.

And then it's pretty tricky to tap through the drill motor shaft, just imagine how strong that metal is. Make sure you talk to a machinist about taping that hole, or consider using steel spring pins or steel dowel pin... Or else, you will break your tap in the drill motor shaft, and probably have to replace it. Use the tools suggested by Andy Baker in quote below.

A question to engineers: Is a steel 1/8" spring pin strong enough for this purpose?


Anyway, you know me and quoting. Here is quoting Andy Baker's exact words:

"Here's what we did, and by the way, this operation was made by a machinist, since no coach or student on our team has ever had sucess doing this operation without buggering it up. So, if you want to do this, get a professional's help.

Put a 3/8" lock washer on the shaft, then thread the motor coupling on (yeah, the one provided by SPI). Screw it on until it bottoms out on the lock washer (lock washer holds it in place).

There is a 1/16" dia. pilot hole on the coupling... use a "spade drill" or a "carbide bit" to drill a pilot hole for a #8-32 screw, all the way through the coupling (this is hard to do).

Once your hole is drilled, use a titanium coated #8-32 tap... I think it's called "titankote" (or something like that)... to tap all the way through the coupling, with the shaft included. Take your time as you tap... don't break it or your gearbox is junk.

Then, put a #8-32 socket head cap screw in there, and voila, a killer coupling attachment.

No, the #8-32 screw is not too big, as long as you don't drill your pilot hole too big."
Closed Thread


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 21:47.

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