# US 2014/0193763 A1 · Expandable raku kiln > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0193763 A1 - Document ID: US20140193763A1 - Status: Published application - Kind: A1 - Application number: 13/842,995 - Filed: 2013-03-15 - Published: 2014-07-10 - Earliest claimed: 2013-01-08 - Inventors: Kellogg S. Johnson - Web page: https://patentgrep.com/patent/US20140193763A1 ## CPC - F27B 17/0041: {specially adapted for burning bricks or pottery (F27B17/0033 takes precedence)} - F27D 1/1808: {Removable covers} - F27B: FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS - F27D: DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE ## Abstract A raku kiln has a fire ring with a cylindrical sidewall and bottom made of refractory material with a kiln shelf supported a few inches above the bottom to enclose a space that is superheated by burners. A firing-chamber rests on the fire ring and is lifted by a two aligned pulleys on top of a pole which rotates to move the chamber out of the way. A vertical pole mates with tubes on the chamber for vertical guidance during raising and lowering of the chamber. Flanges on the lower end of the chamber allow adding an extension chamber. ## Claims ### Claim 1 A raku kiln having at least one burner emitting sufficient heat into a primary tubular firing chamber for firing pottery; comprising: a primary firing chamber with a thermally insulated sidewall and a closed top, the firing chamber having a bottom opposite the top, and at least one vent in the primary firing chamber top, a sub-chamber located below the firing chamber during use, the sub-chamber having a refractory bottom and having a sidewall that provides more insulation to heat transfer through the sub-chamber sidewall than the chamber walls, the sub-chamber having an upper end substantially blocked by a kiln shelf, the burners being directed toward the kiln shelf, the firing chamber having a bottom engaging the sub-chamber sidewall. ### Claim 2 (depends on 1) The kiln of claim 1, wherein the at least one burner is located in a hole in the refractory bottom and emits combusted gases directly against a bottom of the kiln shelf which is located a few inches from the refractory bottom. ### Claim 3 (depends on 2) The kiln of claim 2, wherein the firing chamber has a bottom and a top, with the bottom of the firing chamber resting on a top edge of the fire ring. ### Claim 4 (depends on 1) The kiln of claim 1, wherein the firing chamber has a top configured to engage a lifting device to raise and lower the top vertically. ### Claim 5 (depends on 4) The kiln of claim 4, the firing chamber has a bottom engaging a tubular extension chamber having insulated walls and a bottom configured to engage the sub-chamber sidewall. ### Claim 6 (depends on 1) The kiln of claim 1, further comprising a lifting device having a pulley actuated arm engaging the top of the primary firing chamber during use to and raise and lower the primary chamber vertically along a longitudinal axis of the kiln. ### Claim 7 (depends on 5) The kiln of claim 5, further comprising a lifting device having a pulley actuated arm engaging the top of the primary firing chamber during use and raise and lower the primary chamber vertically along a longitudinal axis of the kiln. ### Claim 8 (depends on 7) The kiln of claim 7, wherein the lifting device comprises a vertical pole having a longitudinal axis and a laterally extending arm having a first end connected to a sleeve constrained to move along a length of the pole and able to rotate about the longitudinal axis of that pole, and further comprising at least one pulley connected to a pulley base that is configured to rotate about the longitudinal axis of the pole; a cable passing over the at least one pulley, the cable having a first end engaging the arm and a second end connected to one of a counterweight or a winch to raise and lower the lift art, sleeve and primary firing chamber. ### Claim 9 (depends on 6) The kiln of claim 6, wherein the lifting device comprises a vertical pole having a longitudinal axis and a laterally extending arm having a first end connected to a sleeve constrained to move along a length of the pole and able to rotate about the longitudinal axis of that pole, and further comprising: at least one pulley connected to a pulley base that is configured to rotate about the longitudinal axis of the pole; a cable passing over the at least one pulley, the cable having a first end engaging the arm and a second end connected to one of a counterweight or a winch to raise and lower the lift art, sleeve and primary firing chamber. ### Claim 10 (depends on 8) The kiln of claim 8, further comprising a first guide tube extending outward from the primary firing chamber, and further comprising: a guide post aligned with the longitudinal axis of the pole and sized to releasably engage the first guide tube and constrain the guide tube to move along the guide post as long as the guide post is engaged with the first guide tube. ### Claim 11 (depends on 9) The kiln of claim 9, further comprising a first guide tube extending outward from the primary firing chamber, and further comprising: a guide post aligned with the longitudinal axis of the pole and sized to releasably engage the first guide tube and constrain the guide tube to move along the guide post as long as the guide post is engaged with the guide tube. ### Claim 12 (depends on 10) The kiln of claim 10, wherein the primary chamber has a vertical height H and the guide post and guide tube engage for a length of at least about H. ### Claim 13 (depends on 11) The kiln of claim 11, wherein the primary chamber has a vertical height H and the guide post and guide tube engage for a length of at least about H. ### Claim 14 (depends on 12) The kiln of claim 12, further comprising a second guide tube extending outward from the extension firing chamber, the second guide tube being sized and located to releasably engage the guide post and constrain the second guide tube to move along the guide post as long as the guide post is engaged with the second guide tube. ### Claim 15 (depends on 13) The kiln of claim 13, wherein the primary chamber has a height H1 and the extension chamber has a height of about H2, and the guide post has and the second guide tube are configured to be engaged for a length of at least about H1+H2. ### Claim 16 (depends on 14) The kiln of claim 14, wherein the primary chamber has a vertical height H and the guide post and guide tube are configured to engage for a length of less than H. ### Claim 17 (depends on 15) The kiln of claim 15, wherein the primary chamber has a vertical height H and the guide post and guide tube are configured to engage for a length of less than H. ### Claim 18 (depends on 8) The kiln of claim 8, wherein the at least one pulley comprises two pulleys each rotating about separate longitudinal axes which axes are parallel and spaced apart, both pulleys being mounted to the pulley base. ### Claim 19 (depends on 9) The kiln of claim 9, wherein the at least one pulley comprises two pulleys each rotating about separate longitudinal axes which axes are parallel and spaced apart, both pulleys being mounted to the pulley base. ### Claim 20 (depends on 19) The kiln of claim 19, wherein the two pulleys are connected by a brace and wherein the pulley base has a tubular portion sized to fit over a distal end of the pole and rotate about a longitudinal axis of that pole, the tubular portion having a closed end of sufficient strength to rest on the distal end of the pole during use. ### Claim 21 (depends on 1) The kiln of claim 1, further comprising: a lifting device having a pulley actuated arm engaging the top of the primary firing chamber during use to and raise and lower the primary chamber vertically along a longitudinal axis of the kiln, the pulley actuating the arm vertically being mounted to rotate laterally in a plane orthogonal to the longitudinal axis of the kiln to allow rotation of the primary firing chamber in said plane. ### Claim 22 (depends on 21) The kiln of claim 21, further comprising a first guide tube extending outward from the primary firing chamber, and a guide post aligned with the longitudinal axis of the kiln during use and sized to releasably engage the first guide tube and constrain the first guide tube to move along the guide post and restrain rotation of the kiln in said plane, the guide post having a length selected to allow the first guide tube to move off the guide post and all rotation of the kiln in said plane.