Re: Degassing Tablets
Posted: Sun Dec 04, 2011 1:44 pm
Thanks for the feedback guys. HT, not sure which part you meant sounds complicated? The tool is simply a bell reducer (3/8" x 1/2") welded to the end of a piece of square tube. There is a shot of it in the video I posted in the Hybrid burner thread. The 3/8" pipe nipple I use to make the degasser packet, wrap a piece of foil around the outside with 1/2" or so hanging off the end. Twist it up then fill the nipple and slide it out so the degasser stay in the foil tube and twist the other end shut. This then stuffs into the bell reducer and is ready to plunge into the melt.
Will take a few pictures next time I am in the shop.
I do preheat my tool at the beginning of each casting session, in fact one time I tried to load it too quickly and set off the degasser. Have to let it cool back down before reloading but I usually have 20 minutes or so between each pour while I am making more molds up so that is no trouble. I make up a bunch of packets and and wait to load the tool right before I am ready to pour the next set of molds.
I might not be using quite enough of the degasser from the sounds of it. The packet I make is about 1/2" diameter and 1" long.
Once I get a chance to mill some more parts up that have been degassed I will report back on any differences I find. Whatever it takes to eliminate the very small porosity I am seeing I will do even if it ends up that I have to buy a tank for nitrogen and go that route. I am almost thinking that might be best in the long run anyhow for ease use and eliminating the noxious gasses.
The way my foundry is set up now I have pretty good ventilation with 2 18" and one 36" fans but if the wind is blowing the wrong way it can kind of mix up the air a little. Working on that now, I picked up some more OSB and 2 x 4s to close in the foundry area more which will make the fans draw better and have less chance of the fumes coming around the end of the wall and back into the foundry. Also thinking about taking the 42" barrel fan I put on my home made porta cool and putting it on my exhaust wall, that thing moves quite a lot of air.
Will take a few pictures next time I am in the shop.
I do preheat my tool at the beginning of each casting session, in fact one time I tried to load it too quickly and set off the degasser. Have to let it cool back down before reloading but I usually have 20 minutes or so between each pour while I am making more molds up so that is no trouble. I make up a bunch of packets and and wait to load the tool right before I am ready to pour the next set of molds.
I might not be using quite enough of the degasser from the sounds of it. The packet I make is about 1/2" diameter and 1" long.
Once I get a chance to mill some more parts up that have been degassed I will report back on any differences I find. Whatever it takes to eliminate the very small porosity I am seeing I will do even if it ends up that I have to buy a tank for nitrogen and go that route. I am almost thinking that might be best in the long run anyhow for ease use and eliminating the noxious gasses.
The way my foundry is set up now I have pretty good ventilation with 2 18" and one 36" fans but if the wind is blowing the wrong way it can kind of mix up the air a little. Working on that now, I picked up some more OSB and 2 x 4s to close in the foundry area more which will make the fans draw better and have less chance of the fumes coming around the end of the wall and back into the foundry. Also thinking about taking the 42" barrel fan I put on my home made porta cool and putting it on my exhaust wall, that thing moves quite a lot of air.