I have thought about using Liquid Nitrogen before for heat treating knife blades? Dry Ice slurry works just fine, but at $6 to $8 each time it gets expensive and a bit of hassle getting the stuff each time. I've always wanted LN, but never considered it due to cost. The dewars were in the $400 range (and still are for a 20 liter size), but a company put a 10 liter on sale for $200 shipped (ebay added $15 tax)
I called around about price to fill the 10 liter dewar. Prices ranged from $15 over in Mobile, to $62 locally in Robertsdale. I called 5 different places, the other 3 places were $40 to $45 to fill. Big spread in price.
I like the U.S. Solid dewar better than the other Chinese made dewars. Per this site https://ussolid.com/about-us/ the website almost seems to sound like "made in USA", but it doesn't say that exactly. Note the "make our own" and "established our own manufacturing" which could sound like "Made in USA", but could well mean they are still made in China, but under U.S. Solid's specs and supervision which would give a chance to be better than the usual "lowest bidder" from China. "In our own research (Spectroelectrochemistry, Femtosecond-laser spectroscopy, Photochemistry and Biophysics) we’ve encountered a series of overly expensive equipment that haven’t satisfied the demands put up to by modern research. We decided to make our own. After some careful analysis we’ve established our own manufacturing and are rapidly becoming viable competition in the North American market."
Anyway, the dewar got here yesterday, I went to fill it this morning. A 2 hr round trip, about 60 miles total. I went to the $15 fill place. I called to double check price, filling, etc. This morning on the phone the salesman told me $8 to fill the 10 liter dewar. Hmmm, that's almost too good to be true. I drove over, when I walked in he says "Sorry, I gave you the wrong price on the phone....... it's $5.50 including tax!" Wow I thinks. I paid the $5.50, took my dewar around back and they filled it. I'm now back home.
Now to see how long the dewar lasts with me playing, freezing grapes to watch them break like glass. AND see how many knife blades I can get treated with that dewar before it runs dry. If you've never played with LN you need to come over and freeze some stuff {g} Throw the frozen grapes on sidewalk and they shatter like glass. The website says the 10 liter will hold LN for 60 days when it's not used. I'm hoping under normal use to get 30 days. I'm thinking I can profile up several blades during the next 20 days or so, then have them HT'd ready for bevels and finishing at my leisure. Anybody care to comment on expected holding time with the 10 liter dewar?
Ken H>
I called around about price to fill the 10 liter dewar. Prices ranged from $15 over in Mobile, to $62 locally in Robertsdale. I called 5 different places, the other 3 places were $40 to $45 to fill. Big spread in price.
I like the U.S. Solid dewar better than the other Chinese made dewars. Per this site https://ussolid.com/about-us/ the website almost seems to sound like "made in USA", but it doesn't say that exactly. Note the "make our own" and "established our own manufacturing" which could sound like "Made in USA", but could well mean they are still made in China, but under U.S. Solid's specs and supervision which would give a chance to be better than the usual "lowest bidder" from China. "In our own research (Spectroelectrochemistry, Femtosecond-laser spectroscopy, Photochemistry and Biophysics) we’ve encountered a series of overly expensive equipment that haven’t satisfied the demands put up to by modern research. We decided to make our own. After some careful analysis we’ve established our own manufacturing and are rapidly becoming viable competition in the North American market."
Anyway, the dewar got here yesterday, I went to fill it this morning. A 2 hr round trip, about 60 miles total. I went to the $15 fill place. I called to double check price, filling, etc. This morning on the phone the salesman told me $8 to fill the 10 liter dewar. Hmmm, that's almost too good to be true. I drove over, when I walked in he says "Sorry, I gave you the wrong price on the phone....... it's $5.50 including tax!" Wow I thinks. I paid the $5.50, took my dewar around back and they filled it. I'm now back home.
Now to see how long the dewar lasts with me playing, freezing grapes to watch them break like glass. AND see how many knife blades I can get treated with that dewar before it runs dry. If you've never played with LN you need to come over and freeze some stuff {g} Throw the frozen grapes on sidewalk and they shatter like glass. The website says the 10 liter will hold LN for 60 days when it's not used. I'm hoping under normal use to get 30 days. I'm thinking I can profile up several blades during the next 20 days or so, then have them HT'd ready for bevels and finishing at my leisure. Anybody care to comment on expected holding time with the 10 liter dewar?
Ken H>
But, what I did was build a plywood box, with a hinged lid. Inside as 2" bigger than the diameter of dewar, and lined the ENTIRE (including the lid) with 2" thick foil backed foam insulation. I place the dewar in the box, and fill ALL the airspace with vermiculite, and top it off with a piece of R30 fiberglass insulation covering the top of the dewar..... With normal use, the LN will last for 35-40 days..... basically doubling how long it lasts versus the dewar alone. I'll get you some pics over the weekend and post them here.
