Enclosures
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From: D Yuniskis on 19 Mar 2010 16:47 mpm wrote: > On Mar 19, 12:32 pm, D Yuniskis <not.going.to...(a)seen.com> wrote: >> I need a small quantity (~20) of small {plastic,aluminum} >> enclosures. But, I'm looking for something other than a >> simple rectangular prism shape. >> >> So far, I haven't found anything "stock" that looks >> appropriate (I did find a COTS "console-like" case but >> the angle is too shallow). > > Have you looked at PacTec Enclosures yet? > Link: http://www.pactecenclosures.com/ Ah, I had forgotten about them! But, no, they don't have anything "stock", either. Everything COTS seems to be "a box" -- with only minor deviations on that "rectangular prism" theme.
From: Joe Chisolm on 19 Mar 2010 18:13 D Yuniskis wrote: > Hi, > > I need a small quantity (~20) of small {plastic,aluminum} > enclosures. But, I'm looking for something other than a > simple rectangular prism shape. > > So far, I haven't found anything "stock" that looks > appropriate (I did find a COTS "console-like" case but > the angle is too shallow). > > If push comes to shove, I can have a friend mill them > out of blocks of aluminum but that seems terribly wasteful! > > I'm wondering, instead, if I can't hack together something > with a sheet metal skeleton (or, maybe even a cardboard or > wooden form!) and fiberglass? This doesn't need to be > terribly strong, structurally. And, I could no doubt > come up with a way of mounting everything to a *base* > (i.e., to eliminate the need for fasteners *in* the skin). > > Has anyone done this sort of thing before? Pointers to > helpful tips as well as things to avoid... :> > > Thanks! > --don I've done fiberglass molds before. If you want 20 or so units I would do a female mold. Modeling clay, foam and Bondo work great for shaping the male plug and fixing any problems. I use tooling polyester resin. Any cheap resin will work. Most local fiberglass suppliers will have some brand. Do not use styrofoam with polyester resin as it will turn into a lump of goo. Use a pvc foam - there are several makes. Use Bondo or some resin with a filler to coat all the foam and make sure and sand smooth. Coat with car wax or some other release agent. Then start to make your female mold from the male plug. Use lots of resin and a fine weave cloth for the first layer. For the other layers I usually use some fiberglass mat and any scrap cloth I have in the bin. Glass in some small wood blocks for stability in making the real parts. Let this all cure and then carefully pop the mold off the male plug. You might have to persuade it a little with a rubber mallet. Clean up any imperfections in the mold with Bondo and some sanding. Dremel with a cutoff wheel works great for cutting the edges of the mold. You can scribe drill marks and cut marks in the mold that will show up on the finished part. I have used a BB bonded to the female mold as a drill "center punch". You can get gelcoat from local suppliers or on the net or you can make a poor man's version using some clear casting resin and some pigment. I have gotten pigment and supplies from TAP Plastic in the past. http://www.tapplastics.com For the final part make sure and wax the mold several times. I usually add some form of spray on mold release as the final step. Lay down a nice layer of gelcoat or resin and then use fine weave cloth for the first layer. If needed stiffen the part by using foam and glass on the inside in various locations. For standoffs and screw inserts you can use a small block of foam. I use screw inserts and just fill the threads with a blob of hot glue. Any resin just pops off and the hot glue plug will pull out of the threads. If there is going to be any real stress on the screws you can carve out a pocket in the foam and fill with a milled glass - resin mix. Let it cure for a minute or 2 to thicken and then push the screw insert into the pocket. Biggest problem I had was making sure they stay aligned. What I did for one part was made a wooden jig where I could screw 4 insert onto locater screws and then pressed them into the milled fiber mix. The jig held everything square. Take a look at http://www.fibreglast.com If you want to go the acrylic sheet method browse US Plastics http://www.usplastic.com -- Joe Chisolm Marble Falls, Tx.
From: Anton Erasmus on 20 Mar 2010 04:53 On Fri, 19 Mar 2010 10:32:42 -0700, D Yuniskis <not.going.to.be(a)seen.com> wrote: >Hi, > >I need a small quantity (~20) of small {plastic,aluminum} >enclosures. But, I'm looking for something other than a >simple rectangular prism shape. > >So far, I haven't found anything "stock" that looks >appropriate (I did find a COTS "console-like" case but >the angle is too shallow). > >If push comes to shove, I can have a friend mill them >out of blocks of aluminum but that seems terribly wasteful! > >I'm wondering, instead, if I can't hack together something >with a sheet metal skeleton (or, maybe even a cardboard or >wooden form!) and fiberglass? This doesn't need to be >terribly strong, structurally. And, I could no doubt >come up with a way of mounting everything to a *base* >(i.e., to eliminate the need for fasteners *in* the skin). > >Has anyone done this sort of thing before? Pointers to >helpful tips as well as things to avoid... :> > Try http://www.tekoenclosures.com/ (USA site, actual fabrication in Italy) RS Components and Farnell sell some of their enclosures. Regards Anton Erasmus
From: Robert Baer on 20 Mar 2010 18:23 D Yuniskis wrote: > Hi, > > I need a small quantity (~20) of small {plastic,aluminum} > enclosures. But, I'm looking for something other than a > simple rectangular prism shape. > > So far, I haven't found anything "stock" that looks > appropriate (I did find a COTS "console-like" case but > the angle is too shallow). > > If push comes to shove, I can have a friend mill them > out of blocks of aluminum but that seems terribly wasteful! > > I'm wondering, instead, if I can't hack together something > with a sheet metal skeleton (or, maybe even a cardboard or > wooden form!) and fiberglass? This doesn't need to be > terribly strong, structurally. And, I could no doubt > come up with a way of mounting everything to a *base* > (i.e., to eliminate the need for fasteners *in* the skin). > > Has anyone done this sort of thing before? Pointers to > helpful tips as well as things to avoid... :> > > Thanks! > --don The idea of "vacuform" comes to mind. Do not know anything about the technology behind this, but it seems that: Make a mold of wood, of the shape and inner size; use 3 degree draft for ease of seperation (mold from part), and if mold needs to be multi-part (in your case i do not think so) then engineer the pieces so they can be pulled away easily. Glop mold release on, then vinyl coat (i think a sheet is used and heat for forming). Then again, once that mold is made, fiberglassing is also an option.
From: Robert Baer on 20 Mar 2010 18:24
Jeremy Bennett wrote: > On Fri, 19 Mar 2010 10:32:42 -0700, D Yuniskis wrote: > >> Hi, >> >> I need a small quantity (~20) of small {plastic,aluminum} enclosures. >> But, I'm looking for something other than a simple rectangular prism >> shape. >> >> So far, I haven't found anything "stock" that looks appropriate (I did >> find a COTS "console-like" case but the angle is too shallow). >> >> If push comes to shove, I can have a friend mill them out of blocks of >> aluminum but that seems terribly wasteful! >> >> I'm wondering, instead, if I can't hack together something with a sheet >> metal skeleton (or, maybe even a cardboard or wooden form!) and >> fiberglass? This doesn't need to be terribly strong, structurally. >> And, I could no doubt come up with a way of mounting everything to a >> *base* (i.e., to eliminate the need for fasteners *in* the skin). >> >> Has anyone done this sort of thing before? Pointers to helpful tips as >> well as things to avoid... :> > > Have you considered 3D printing in plastic. I have a friend in a > university lab who routinely does this for prototype enclosures. > > Jeremy > Expensive as all hell; buy sheets of plastic and solvent glue them together. |