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Unread 02-22-2006, 01:48 AM   #1
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Join Date: Jan 2006
Location: Ann Arbor, MI
Posts: 34
Default acrylic joint fitup?

hey I currently have a modding project for my sophmore fabrication project at uni. Needless to say while it rocks to get a grade for modding and have access to a full fabrication and machine shop I need perfection and it's an ambitious project. to make a long story short I have an 1/8" acrylic sphere and I need to cut some holes in it. First of all I'm just guessing preventing this giant (24") globe from cracking is going to be a pain, and that I'll have to make a wood die on the insides to take the weight of the drill and prevent deformation and maybe help with squaring.
now here's my questions I need to make some clean joints. the problem is I'm trying to mount clear acrylic tube to a sphere so just joint fitup and squaring is going to be strange, the real problem is does any one know the tolerance of hole saws? and acrylic tube? I was thinking of using 4.5" acrylic tube and a 4.5" hole saw but I'm not sure of dimension tolerance as I believe acrylic needs a flush joint? I suppose I could cut say 1/2" too small and ream it out with a die grinder, but as you all know trying to get an exacting cut in plexi with hand tools isn't easy.
also can anyone reccommend cements or glues for acrylic? this tube wouldn't be under any other force save for its own weight. I also have access to a plastic welder but hot gas plastic welding tends to deform vaccum formed acrylic.
Any general guidelines to cutting holes in acrylic (especially formed spheres)
That sphere is $150 so I don't want to fudge it on the hole cutting, drilling, or bonding.
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