Original poster: "huil888" <huil888@xxxxxxxxxxxx> The TCML wrote: "When drilling SS you need to go slow and keep from heating, the heat hardens the SS as your drilling." Actually, with regards to the 300-series stainless steel material used in the gazing balls, this is NOT true. Heating the material will soften (anneal) it, not harden it. What is happening is that the material has already been work-hardened by the spinning or deep-drawing process used to form the half-spheres, and any additional "cold-working" will continue to rapidly increase the hardness. When drilling, you MUST use a dead-sharp drill bit, the bit must start cutting the instant it first contacts the workpiece, and you must maintain pressure on the bit until you penetrate the material. Allowing the drill bit to spin against the material without actually cutting immediately work-hardens the material under the bit and further increases its hardness. You can see this effect easily when working with half-hard or 3/4-hard stainless steel sheet. If you just try to drill a hole in this material with a sharp drill bit, the bit will instantly "bite" into the material and start cutting. If you center-punch the material first to locate the hole, the act of center-punching the material will locally work-harden it to the point that the bit will not bite, it will just spin aganist the material and get hot. There are a few speciality alloys that have the characteristic of "precipitation hardening", that is, they will increase in hardeness if they are maintained at elevated temperatures for a specific time, but gazing balls are not made from these expensive materials. Regards, Scott Hanson ----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx> To: <tesla@xxxxxxxxxx> Sent: Saturday, October 21, 2006 12:48 PM Subject: Re: Gazing Ball Terminal ?
Original poster: Stan <wsmg@xxxxxxxxxx> When drilling SS you need to go slow and keep from heating, the heat hardens the SS as your drilling. What I found to work best is using a hand drill and inching it. Tesla list wrote:Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx> Hi Dave, At 12:01 PM 10/21/2006, you wrote:Hi again, sorry to be a pest :-( , but, your gazing balls come with a small hole in them ?Yes, I enlarged them yesterday with one of those multi size bits: http://www.sears.com/sr/javasr/product.do?cat=Power+Tool+Accessories&pid=00920921000 It is pretty hard on the expensive drill bit... Go real slow and gentle since the stainless steel is super ultra hard (they will NOT dent easily!!!)!!! Let the bit do the work with a little cutting oil. I drilled to a little less than the final size and then reamed the hole exactly: http://www.sears.com/sr/javasr/product.do?cat=Hand+Tools%2C+General+Purpose&pid=00940884000 Then you hold it with the hole straight down and shake it for ten hours trying to get the &^%&$ shavings out. Also had to de-burr the hole a little..., is there any coating on it ? I though I read there was, but, ??????????? .. I see the "Mystic " ball has the coating , ..........:-(The cheapest "silver" or bare ones are just bare stainless steel. The mystics might look real cool if you got them! The base steel is indestructible if it is a disaster and you had to strip the coating.Also, when you slip your slider tube in and epoxy it, how will you assure its directy in the center ? , some kind of jig or somethin' ?Yes, I will have to make a jig to hold the ball centered and the rod perfectly perpendicular to the ball. I will pour epoxy into the hole so it smears inside opposite the hole to hold the far inside end. I was thinking of using conductive epoxy on the outside end but maybe I will just leave it for the moment. The holes are fairly tight.Heck, I dont know!!! Man, your gonna have one awsom coil !!!:-)) Mostly working on the wood box today while the weather is reasonable. I will CC the list too since others may have such questions. Cheers, Terry