Glen, Your point is well taken. I have a couple of reasons why we look to build stuff in our garage.
1. We're engineers...That's what we live for! You're dealing with a man who has invested hours of cutting, planning, scraping, thinking...to make a dining room table since last February...when I could buy one for $150 at Walmart. (Although, you could park a hummer on the one that I'm making...and the one at Walmart would be lucky to support a hummingbird) 2. Some manufacturers don't do themselves any favors by price gouging such ancillary equipment. For instance, we have an ESD gun from a "to be unnamed" manufacturer. We bought the gun; and we were offered "Horizontal Coupling Planes" for $1500 and "Vertical Coupling Planes" for $750. Being new to EMC, we thought that they must be some highly complex devices. But, we researched and found that they were just metal plates with a resistor loaded wire and alligator clips. We made both the HCP and VCP out of Aluminum obtained locally for about $200 in materials...compared to the purchase price of $2250. 3. Obtaining the billiard balls for the bearings could be an adventure. For instance, a race with a 2' diameter would have a 75" circumference; which would require an estimated 37 cue balls (assuming 2"diameter). These could be gotten for free if you just went bar hopping for a few weekends and stole the cue balls from the bars...For engineers what could be better? Bar hopping, socializing, shooting some pool, obtaining materials and making something neat. By the way, I have enough scrap lumber and plywood around to make such a device. I also have a fully equipped 1400 sq ft wood shop where I live. So to mimic an old visa commercial... Plywood----free 2 by 4s----free One broken jigsaw blade-------$2 37 cue balls-------37 beers and 74 quarters An excuse to go bar hopping ending with a little time in the shop....Priceless Respectfully submitted from one of the last individualists. Chris Maxwell Nettest From: Glen Watkins [mailto:[email protected]] Sent: Thursday, August 26, 2004 3:23 PM To: [email protected]; Chris Maxwell; [email protected] Subject: RE: Turntable design/construction Speaking as a manufacturer of tables like the ones described here, and reading all of the various comments, I have to wonder how much money is really being saved building one in the garage over purchasing of a ready made system that is guaranteed to work, includes a warranty, and has people ready to support it when (and if) something breaks. Not to mention electronic controlling systems with GPIB interfaces, etc. From: [email protected] [mailto:[email protected]] Sent: Thursday, August 26, 2004 1:48 PM To: [email protected]; [email protected] Subject: RE: Turntable design/construction How about a Formica layer on the wood to prevent the billiard balls from denting the wood. Or, instead of that, make the bottom layer of plywood some nice oak plywood. Dave Cuthbert Micron Technology From: [email protected] [mailto:[email protected]] On Behalf Of Chris Maxwell Sent: Thursday, August 26, 2004 11:47 AM To: IEEE EMC-PSTC GROUP Subject: RE: Turntable design/construction Races for a "cue ball bearing carousel"...Hmmm... There are probably a million ways to skin this cat. May I recommend the following: Obtain pieces of plywood that are as big as the outside diameter of your race, allowing a couple more inches for the outside of the race itself. For instance, if your race is to have an outer diameter of 2', get (or cut) pieces that are about 2'6" square. Mark one piece with two concentric circles. One circle for the inside diameter of the race, one circle for the outside diameter of the race. You will need to stack a couple (or few) of these pieces in order to get the proper thickness for the race. For instance, if the billiard balls are 2" in diameter, stack two pieces 3/4" thick in order to get a nice, 1-1/2 inch thickness, which leaves 1/2" of billiard ball diameter protruding for your "ball bearing" surface. So...stack your pieces up with the marked one on top and a coating of yellow glue between them and screw them together with regular old wood screws on a grid of about 4" to 6" in each direction. Pick screws that will connect all of the pieces together without protruding too far through. Make sure that you don't put screws on the circles that you drew. Buy, borrow or steal a jigsaw and cut the inner circle. (You just need to drill a hole in the waste area to start the blade) (Leave the line as a guide for a belt sander or file). Then cut the outer circle. You should now have the inner and outer sections of your "race". Sand, file...whatever to get the circles smooth enough to do the trick (I have fallen in love with "microplane" files. They work like a cheese grater and smooth up stuff in a hurry) Now all you need to do is figure out how to pivot the table on your race (maybe a rod up through the middle) and what to put under your race to support the billard balls. Epoxy on a piece of plywood (as Ed suggested) may be a good idea The nice thing about it is: you can make the support disposable. For instance, if your epoxied plywood gets worn out after a while, remove your race pieces from it, gather up your cue balls and put the whole shebang on another piece of plywood (or whatever you use for support) The billiard ball idea for bearings is a hoot! I'm just now trying to figure out an excuse to use this idea in my home shop. Frustrated woodworking EMC engineer, Chris Maxwell Nettest PS, after going through all of this...I beg to ask the question. Does your test setup have a ground plane? If it does, a metal carousel under your ground plane is sort of a moot point. If not, then the billiard ball idea sounds pretty neat to me. PS # 2... If you decide to try the "lathe-like" operation that Ed Price suggested...A 1/4" lathe parting chisel would work the best. You may get some nasty splinters/kickback/other annoying repercussions if you use a regular wood chisel. Definitely wear good gloves and eye protection...if not a chain mail suit!!! This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
