Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: pomprocker on March 31, 2008, 09:14:27 PM

Title: $50 MOBOT and ERP
Post by: pomprocker on March 31, 2008, 09:14:27 PM
What is that black material that is used for the base in the documentation of these two robots?
Title: Re: $50 MOBOT and ERP
Post by: Webbot on March 31, 2008, 10:36:45 PM
Quote
these two robots
Some kind of link would help. We know lots of robots  ;D
Title: Re: $50 MOBOT and ERP
Post by: pomprocker on April 01, 2008, 01:03:23 AM
its on the SoR pages here under robots.
Title: Re: $50 MOBOT and ERP
Post by: cooldog on April 02, 2008, 05:07:14 PM
there ared 19 of them which one

these 2

http://www.societyofrobots.com/robot_ERP.shtml

http://www.societyofrobots.com/robot_mobot_2007.shtml

i thinks it's black HDPE (does it come im black?)
Title: Re: $50 MOBOT and ERP
Post by: pomprocker on April 02, 2008, 06:04:02 PM
I was thinking either carbon fiber or acrylic
Title: Re: $50 MOBOT and ERP
Post by: Admin on April 06, 2008, 10:44:41 AM
I think its acrylic (or delrin?), I forgot what I used . . .

Its my new favorite material ;D
Title: Re: $50 MOBOT and ERP
Post by: pomprocker on April 06, 2008, 03:58:54 PM
Why is it your new favorite matierial?

HDPE has so many good properties!
Title: Re: $50 MOBOT and ERP
Post by: Admin on April 06, 2008, 05:14:28 PM
The best part of HDPE is its the easiest material to cut yet its still strong and lightweight and cheap.

However, the material is soft, scratches easily, and isn't that rigid. The translucent color also doesn't look as professional as a pure white or pure black color (like on my ERP).

Acrylic, nylon, and delrin have the advantages but not those disadvantages - but typically more expensive . . . Since money isn't a factor for me anymore, I no longer use HDPE . . .

Just search for those materials at mcmaster.com to compare - you may discover new options!
Title: Re: $50 MOBOT and ERP
Post by: pomprocker on April 06, 2008, 09:03:01 PM
What kind of thickness do you recommend on acrylic/delrin?



I found this place in Southern California, in Anaheim right next to the Angel's stadium that offers will call pickup.

http://www.indplastic.com/ (http://www.indplastic.com/)


I just bought some HDPE there, very good service
Title: Re: $50 MOBOT and ERP
Post by: Admin on April 06, 2008, 09:18:49 PM
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What kind of thickness do you recommend on acrylic/delrin?
1/6" is strong/rigid enough, but I often use 1/4" so I can tap it and put spacers and screws into it securely.

Oh, and its a bit heavier than HDPE, but I cut large holes into parts to reduce weight - like in the arms of my ERP.
Title: Re: $50 MOBOT and ERP
Post by: pomprocker on April 07, 2008, 03:31:33 PM
How is the caster mount on these two robots constructed?
Title: Re: $50 MOBOT and ERP
Post by: Admin on April 07, 2008, 04:43:59 PM
There are two flat plates with holes drilled halfway through the center of them. Then I used a .25" rod and placed it into both holes, with the rod also inside the caster wheel.
Title: Re: $50 MOBOT and ERP
Post by: Admin on April 11, 2008, 06:55:22 AM
Ok I looked it up.

I am using delrin on my ERP. Its about twice as strong, twice as rigid, heavier, and about twice the price of HDPE. In fact, I used about $80 worth of delrin on my ERP (per version).

However, because its so much stronger, I can use my CNC and FEA to cut away large holes into all my parts to dramatically reduce weight without sacrificing strength. If I didn't have a CNC or money to spare, delrin would probably not be my new favorite material.