On Sunday, February 05, 2012 02:42:38 AM Erik Christiansen did opine: > On 04.02.12 18:04, gene heskett wrote: > > What would you folks use when you need an insulated pallet? > > If nothing out of the junkbox will do, I'd fish out my old tin of > automotive bog and make up a few suitably sized slabs. Admittedly, > they'd have to be machined on the outside too, to make them look half > respectable. > > If that isn't stable enough, then I'd fork out the $30 - $40 that a 3/8" > or 1/2" sheet of acetal (Delrin equiv.) costs here: > > http://www.iplasticsupply.com/shopping-cart/acetal-delrin-celcon-sheet/ > > or anywhere else handy. With shipping too, it's worth being inventive, > though. > > Here's hoping that the automotive filler will do. I've machined it after > filling in a missing bit in an aluminium casting, and it cut fine. (I > only had to mount a fuseholder there, so it was strong enough.) > > Erik
I hadn't considered the bondo approach, mainly because I tried to fix a broken tower on an ignition coil with it something like 50 years ago, and it shorted out the coil. The fire could be seen jumping from the wire socket on the inside, about an eighth inch, then back to one of the low voltage terminals on the side next to the bondo. That was a 60 kilovolt rated, rather high priced 'hot rod' part at the time. I made a new pallet out of micarta last night, including a "fits the T slot" fin on the bottom to maintain x axis alignment if I dismount & remount it, and it scans with a dial indicator on the mounted pcb with a variation approaching a full thou. My micrometers can measure that much just from thickness tolerance on the pcb, so I doubt if I'll get too much better unless I run down a more precisely made board than what the shack is peddling. I put a locator hole in the pallet, then thought I would re- enforce the hole with a short piece of brass tubing with a 1/16 bore from the hobby shop, something I could use my hole finder routine to locate its exact center, then run the machine to the corner of the board using the step jog function & home the machine there. Or I could home it there and just plug in those small, known offsets with G92. That leaves one final problem. That of reliably finding the boards own reference hole once the board is turned over to do the bottom side. I've found the 1 oz copper is quite easily pushed out of the way, so the hole finder can't reliably find the sides of the hole, no probe contact. So tomorrow I will get one of those pcb pens from the shack and see if I can dummy up a thou or 2 of 'plated thru' down into the hole with it, which should make that contact area quite a bit more robust, even repairable if I wear it out by repeated probing. Progress at least, and I'm certainly learning a lot about my machine. For one, if I don't keep the z post swimming in vactra, it shudders as it moves in about 2 thou jerks, possibly telling me I have the gibs too tight, so that is something else I need to fine tune tomorrow, but from the looks of the doppler radar page, we may have, if there is any left when it gets here in an hour or so, some of Denvers snow to shovel first. It was moving pretty fast when I looked about an hour back. Thanks for the suggestions Erik, you never know when something said on 16th Avenue (Rosanne Cash) might be magic. ;-) Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> There cannot be a crisis next week. My schedule is already full. -- Henry Kissinger ------------------------------------------------------------------------------ Try before you buy = See our experts in action! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-dev2 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
