Nov
10
Dan R technique MOLD ACRYLIC PLEXI MAKE A PARABOLIC MIRROR CUT A CIRCLE SAW
By
www.greenpowerscience.com CUTTING A PERFECT CIRCLE ON A TABLE SAW. MAKE A PARABOLIC MIRROR COPYING A PARABOLOID. MAKE PERFECTLY BALANCED FLYWHEELS OUT OF WOOD. THIS METHOD FINDS THE PERFECT CENTER WITH NO MEASURING. THE SAFE WAY TO CUT A PERFECT CIRCLE ON A TABLE SAW.
25 Comments
November 10th, 2009 at 1:07 am
love ur vid and thanks for posting, i wanted to say right away- and yes i am a laymen here- you dont have to drill into your table saw u only need some C clamps and wood and put the screw in the underside of the wood , thread side up, and there u go.
i would imagine one should be able to cut one time all the way around if you work VERY slowly-. hah?
November 10th, 2009 at 1:32 am
I agree. might need thin strips to keep from wrinkling too much. it might also be possible to just heat remove the paint on a dish and polish it like Dan R here suggests in another of his videos. but if you want many done right I still believe in vacuum molding clear thermoplastic on a parabolic dish as a mold and then coat it with a chemical mirror like silvernitrate like this: watch?v=hUX_cpFWNso
November 10th, 2009 at 2:08 am
I’ve always wanted to try gluing some aluminum foil to an old satellite dish just to see how well it concentrates sunlight. Al foil is very shiny on one side and should work, I think.
November 10th, 2009 at 3:05 am
21 holes now:-) Still works perfect. I cut a 6ft dia base out of 2×4 glued and screwed together. Cut the circle with a steak in the ground 36″ from blade and a pin pivot. 5 minutes to cut through 2×4s
Rolls like a tire, really cool.
November 10th, 2009 at 3:14 am
I agree – in a throw away society my point sounds highly moronical
In engineering a jig means no machine modification
Maybe I can wriggle out by pretending I was thinking about countries where these machines might cost several months wage – and drilling holes in a loan machine is not an option
November 10th, 2009 at 3:26 am
You sound like YOU’RE the one not thinking. He bastardized the saw by just drilling one 1/4″ hole? And if the plywood circle isn’t a JIG, what the hell is it? You think he cuts another wood circle every time he wants to cut another piece of plexiglass? You must be a moron.
November 10th, 2009 at 4:11 am
You didn’t show yourself removing the finished mirror from the glass parabola form. Does it remove easily or does it stick? I’m sure you’d have to allow it to cool but you skipped through these details. And that mirrored plexiglass is expensive. But this is a very cool method overall.
November 10th, 2009 at 4:43 am
Duh, mount a sheet of plywood to the tabletop! Of course, make sure that you have a dowel, or a nail located where you want the radius of your cut to be. Then drop your material which you are cutting onto the nail (or have a hole drilled in the material, and mount the hole where the dowel is). Then raise, and spin!
November 10th, 2009 at 4:44 am
DO NOT EXCEED 190F.
The Curve does not have to be a true Parabola for solar as the target heated is usually larger than the spot produced. These actually cast an image reflection that it pretty good. True parabolas are great but for solar, not worth the time.
In regards to chrome paint, it does not work well. Chrome plating does but the dish requires stripping. If you go that far you should just do this:
watch?v=f8kYbOb2TwA
Thank you for the comment:-)
November 10th, 2009 at 4:58 am
I tried melting plexiglas in an oven once. made the food taste of burned plastic. don’t use a food oven.
also there is no guarantee that a curved product is parabolic. a parabola is a very particular curve, not just any curve.
why not use a small satellite dish as the mold, vacuum form onto it and mirror coat the backside, either the chrome paint you can get or silver coating. that should get you an actual parabolic mirror and good size
November 10th, 2009 at 5:30 am
Great work! Keep it up!
November 10th, 2009 at 6:05 am
I cut about 15 circles a day this way, have one saw “bastardized?”:-) just for that purpose. Works on wood and acrylic. The only jig I have is for hole free cuts. Keep in mind, this is a $129 dollar saw.
All my sizes are fixed and it works fast. Amazing made three round 1/4″ acrylic counter tops 30×30 for a local store in 15 minutes.
November 10th, 2009 at 6:28 am
wrong again…..:) to make a perfect circle you should use a CNC
November 10th, 2009 at 7:05 am
and no holes in your table saw…
November 10th, 2009 at 7:19 am
I second psychomikeo500 – it’s totally bad form to bastardize your tools – make a jig like a pro
It’s not the waste of the tool that is important – it’s the lack of creative thinking that is the problem – making jigs will stand you in good stead for other projects
November 10th, 2009 at 7:32 am
To make a perfect Circle you should use a Router on a string=perfect every time even for a beginner.set a nail in the center and adjust the length of the string to get the size radius U want.
Perfect every time!!
November 10th, 2009 at 8:00 am
this is awesome
November 10th, 2009 at 8:47 am
Awsome use of the saw! I cut larger arks with a skillsaw but never tried such a tight radius!
I found plexiglass at delviesplastics
November 10th, 2009 at 9:30 am
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November 10th, 2009 at 9:46 am
This is awesome !
November 10th, 2009 at 10:01 am
where do you get a plexi glass mirror?
November 10th, 2009 at 10:49 am
i would have made a jig that locates in the miter slot and could have then made a movable pivot in the wood panel laying across the saw top.
November 10th, 2009 at 11:01 am
absoultely freakin awesome, nice work and good use of the table saw!~
November 10th, 2009 at 11:39 am
You showed that shop teacher xD
November 10th, 2009 at 11:57 am
CAPS I LIEK TO TALK IN THEM!!!!!!