Polycarbonate Information Page

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5	<td valign="top" ><font size="2" face="verdana"><strong>Polycarbonate Information Page<br>
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7	Updated <!--webbot bot="Timestamp" startspan s-type="EDITED" s-format="%m/%d/%Y" -->07/30/2007<!--webbot bot="Timestamp" i-checksum="12528"
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9	<p><font size="2" face="verdana"><b>Why Polycarbonate?<br>
10	</b>Some of our robots use Polycarbonate. Why, because it is very strong. The image to the right is of me trying really hard to bend one of the
11	H2 bottom panels. It really hurt holding this long enough  for the camera to snap the image. When I let go it returned to its normal flat
12	shape, no worse for the wear. Now Polycarbonate is not indestructible, but it is very tough. A 1/8" thick x 1/4" wide strip can be
13	broken, but it takes several back and forth bends before it finally breaks.  </font></p>
14	<p> </p>
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16	<td align="center" valign="top " width="320"><img src="./Information on Polycarbonate_files/lexan01s.jpg" border="2" hspace="10" width="320" height="240"><br>
17	<strong><font size="2" face="verdana">Will it Break? No!<br>
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22	<td valign="top" ><font size="2" face="verdana"><b>Laser-cut Lexan properties</b> <br>
23	The cut edge has a black residue which can easily be cleaned with a damp rag or paper towel. It is normal and can't be helped. When the residue
24	is cleaned off, the edge will still be darker than the material. The dark edge is going to be present no matter what color the Lexan is. Most
25	people like the way the cut edge looks, but there are some who would prefer not to have the dark edge. Technically, it would be possible to try
26	to polish the edges, but beware it would be a very labor intensive project, and not worth the trouble in my opinion. <br>
27	<br>
28	<br>
29	</font></td>
30	<td align="center" valign="top" ><img src="./Information on Polycarbonate_files/lexan02.jpg" border="2" hspace="10" width="320" height="240"><br>
31	<font size="2" face="verdana">Figure 1.<br>
32	<br>
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36	<td valign="top" ><font size="2" face="verdana"><b>Lexan protective covering</b> <br>
37	The Lexan pieces have a protective covering that needs to be removed before assembly. When the laser cuts, the covering melts into the cut edge
38	which can make removal difficult. If you gently scrape the cut edge with a metal edge, such as a flat blade screw driver, the covering can
39	easily be separated with a thumb nail. </font></td>
40	<td align="center" valign="top" ><img src="./Information on Polycarbonate_files/lexan04.jpg" border="2" hspace="10" width="320" height="240"><br>
41	<font size="2" face="verdana">Figure 2.<br>
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46	<td valign="top" ><font size="2" face="verdana"><b>Peal and Separate</b><br>
47	Once it is started the covering easily peels off of the pieces. Note, you only want to scrape the edge. If done properly the pieces will not be
48	damaged at all. <br>
49	</font>
50	<p> </p>
51	</td>
52	<td align="center" valign="top" ><img src="./Information on Polycarbonate_files/lexan05.jpg" border="2" hspace="10" width="320" height="240"><br>
53	<font size="2" face="verdana">Figure 3.<br>
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58	<td valign="top" ><font size="2" face="verdana"><b>Stubborn Coverings</b><br>
59	From time to time the coverings can be more difficult to remove. If you have trouble you can gently scrape the cut edge as explained above, then
60	put a piece of Duct Tape over it, then rip it up. This really works pretty well. </font></td>
61	<td align="center" valign="top" ><img src="./Information on Polycarbonate_files/lexan09.jpg" border="2" hspace="10" width="320" height="240"><br>
62	<font size="2" face="verdana">Figure 4.<br>
63	<br>
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67	<td valign="top" ><font size="2" face="verdana"><b>The Finish</b><br>
68	Lexan has a beautiful mirror smooth finish. However, in time it will get tiny surface scratches due to cleaning and normal wear and tear. It
69	isn't really that noticeable, but under the right conditions it can be visible. Note: this step is optional!</font>
70	<p><font size="2" face="verdana">There are some options for modifying the finish.</font></p>
71	<p><font size="2" face="verdana">The Lexan parts can be sand blasted with a fine medium. I especially like the look on the black
72	components.  </font></p>
73	<p><font size="2" face="verdana">The parts can be lightly sanded by hand, or with a random orbit sander with extra fine sand paper. This is easy
74	to do, but should be done carefully to avoid removing too much material. The key is to make light even passes with the sander. </font></p>
75	<p><font size="2" face="verdana">The result is a durable charcoal gray appearance that can't be scratched, because it has been pre-scratched in
76	every direction.<br>
77	<br>
78	Lexan can also be painted, but use paint specifically designed for use with Polycarbonate. Your local hobby shop can help with this. There
79	has also been some new developments in the paint industry specifically for plastics. Check out Krylon Fusion. <br>
80	</font></p>
81	</td>
82	<td align="center" valign="top" ><img src="./Information on Polycarbonate_files/lexan03.jpg" border="2" hspace="10" width="320" height="240"><br>
83	<font size="2" face="verdana">Figure 5.<br>
84	<br>
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88	<td valign="top" ><font size="2" face="verdana">Here is an image of our old Pan and Tilt with the random orbit finish.<br>
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90	<td align="center" valign="top" ><img src="./Information on Polycarbonate_files/lexinf06.jpg" border="2" hspace="10" width="320" height="240"><br>
91	<font size="2" face="verdana">Figure 6.<br>
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95	<td valign="top" ><font size="2" face="verdana"><b>Finishing the holes</b><br>
96	The holes in the panels just need a bit of a push and they just fall out. I am using a 3/32" ball end hex driver here. It works quite well
97	and it's required to build the kits anyway.  <br>
98	</font></td>
99	<td align="center" valign="top" ><img src="./Information on Polycarbonate_files/lexan06.jpg" border="2" hspace="10" width="320" height="240"><br>
100	<font size="2" face="verdana">Figure 7.<br>
101	<br>
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105	<td valign="top" ><font size="2" face="verdana"><b>Separating the parts</b><br>
106	Some of the kits have parts nested to simplify packaging and reduce errors. Larger parts can be snapped apart. The smaller parts can be easily
107	separated with a hobby knife. Be careful! Use a large wood backer and work slowly. <br>
108	</font></td>
109	<td align="center" valign="top" ><img src="./Information on Polycarbonate_files/lexan07.jpg" border="2" hspace="10" width="320" height="240"><br>
110	<font size="2" face="verdana">Figure 8.<br>
111	<br>
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115	<td valign="top" ><font size="2" face="verdana"><b>Separating the optional openings</b><br>
116	Some of the kits have optional openings that need to be cut out before assembly. Carefully press a flat Exacto knife into the opening where the
117	part is attached to the main panel. <br>
118	<br>
119	Caution! Do not attempt to snap these optional openings apart.  <br>
120	</font></td>
121	<td align="center" valign="top" ><img src="./Information on Polycarbonate_files/lexan08.jpg" border="2" hspace="10" width="320" height="240"><br>
122	<font size="2" face="verdana">Figure 9.<br>
123	<br>
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127	<td valign="top" ><font size="2" face="verdana"><b>Caution!</b><br>
128	Lexan is the same material used in bullet proof glass. It is very strong, but has one important weakness. In the presence of certain chemicals,
129	it will "craze". This means it will crystallize, become brittle, and even shatter. One substance in particular to watch out for is 1,
130	1, 1 Trichloroethane. This is a solvent, present in some motor cleaners and degreasers, which will crystallize polycarbonate on contact.
131	Trichloroethane is a liquid CFC and has been removed from use, but may still be out there. Some products have switched to its cousin, 1, 1,
132	Difluoroethane. While not as vigorously reactive as the previous chemical, it is still capable of crazing Lexan if allowed to come into contact
133	for too long. Also avoid using Loctite or thread locks on the chassis assembly. They are not necessary and may cause damage to the Lexan.<br>
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139	<td valign="top" ><font size="2" face="verdana"><b>Other Information</b><br>
140	Lexan is a bit on the expensive side compared to foam PVC and acrylic, but the added strength makes it well worth the added cost. It can be
141	drilled and cut easily using standard wood working tools. Use a low speed on the tool and low feed rates to prevent the plastic from melting to
142	the tool. Have fun building your robots, and above all be careful!<br>
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