For the time being I slapped this together but it actually works. In the somewhat near future, "if" I don't end up buying a lathe, I'll build another jig with an electric motor, variable speed controller and the works. Jason bet me I'd end up breaking the very first one I bored. Well, Jason, as you can see this jig works like a charm and I didn't break a single one.
Nice OCD. Let us know what kind of life you get out of them. They are a consumable. The 1/4" TCs are economical but they do cut down on the available wall thickness of the gouging rods. I use 1/8" Inconel sheathed K-TCs and it gives you more wall thickness and life per sheath. They seem to have good contact with the sheath and response time. Build yourself a holder with a stand to hang it on. They're fragile and especially so when hot so it's good to have a place close by where you can quickly hang them. Best, Kelly
Got a link for the 1/8" Inconel K-TC's? Just tried looking them up on McMASTERS and don't see them. I just went with what was recommended but would like as much meat left as possible on the gouging rods.
I watched eBay and finally found the high temp range 1/8" Inconel units on Amazon comparably priced to the 1/4" ceramic separator types at McMaster. Mine are 18" length just because that's how I'm set up but it does give the connection good distance and thermal isolation from the melt so I can use a common mini k-type connector. I paid $30 delivered but shorter lengths are more economical. Search Inconel K thermocouple on Amazon or eBay. Be sure to check temperature range. -Not all K-Types are created equal. I have a similar 6" long 1/8" K-Type Inconel inserted through the lid of my electric furnace for temp control. It's been in service at <=2000F for over a year now. I think you have seen my set up but I can post again if you want. I have a chunk of stainless tube as an extension to the gouging rod to get the TC out of the furnace. Best, Kelly
OCD, that's a really simple, but effective solution. How about adding a drill guide at the front, sized exactly for your 1/8" & 1/4" drills (or 7/16") then the drill would be concentric without eyeballing...
If you talking about adding the throat guide for the drill bit at the end of the gouging rod tube guide you can’t as the rod has to be able to travel all the way down the drill bit to bore out the ID. The ideal setup is a bolt anchored motor with a chuck and a speed controller which allow you to adjust the placement and speed of the drill bit.
...but couldn't it just be a bushing you slide in to start the drill on center and then remove it once that has been done? Getting it started on center for the first few inches is probably the most critical part. You have to clear chips frequently or it will load up and break the rod. Best, Kelly
I've had good luck drilling it by hand with a small drill bit the first couple of inches. After that, the long drill bit usually follows the pilot hole. I'm going to see if I have some scrap tube laying around and try this.
A removable bushing would work to get you started. Being blind in 1 eye and barely able to see out of the other I need all the mechanical help I can get.
Forgot to mention, when you drill out the holes in the wood for the metal tube guide drill it with a forstener bit.
I tried just about every known piece of piping which would provide a snug fit for the gouging rod and nothing was adequate except a piece of tubing which I salvaged from a crutch. Upon pondering how to make this little contraption a little easier to build I came up with the following. Take a piece of 1/2” ID PVC piping and drill it out with a 11/16” bit. The rods measure right at .627 / 5/8” OD. This will give you 1/32” clearance around the rod for sliding. Now, for the bushing guide. Use a piece of 3/4” ID PVC pipe, a coupling and a screw in end cap. You could also fill the ID of the end cap with epoxy or pack it with JB weld to give you a deeper/meatier guide throat for the drill bit. Drill your center guide hole on a drill press, slip onto the 3/4” ID pipe and slip that over the end of the smaller rod guide pipe. This same method could also be used for a larger drill bit if required, to get a perfectly straight hole started.
I think it's easier to send you a box of rods and some beer and say drill 'em.... (did your neighbors calm down yet?)
Forcefully....... yes. Did what I had to do when the wife started getting riled up about it. They scattered like roaches.
Neither have I. Can you send me yours so I can play with it for a feeeeewwwwww years? I promise to make sure it's tucked in snuggly during the winter and it gets to bed on time. Oh, Kelly, I do have one of those 1/8" Inconel thermocouplers with the porcelain plug at the end. I just can bring myself just yet to stuff it into the belly of the beast. If the gouging rods go POOF, then yeah, it's going to be getting used.
I use 5/8 inch gouging rods in bronze and get at least 25 or 30 dips out of one. Probably more. Here is a tutorial I posted years ago over on AA that explains how I make these things. It also explains in simple terms how thermocouples work. http://www.alloyavenue.com/vb/showthread.php?11337-Original-Post-of-How-to-Make-and-Use-a-Pyrometer Richard
