Harry C Shoaf ONE OF frustrating problems scale modeler often faces locating making proper wheel tireespecially tire would seem now wheel manufacturing companies would have complete line kinds sizes True can find fair selection air-wheel types few others like pre- World War World War 20s 30s wonder pet model areas WW flying scale usually around 1 inch ot Years ago thought ng people would surely have sizes wanted No luck tire diameter right section size would too thin usually ended up er tubing lousy joint using slug dowel finally discovered good joining method however consisted searing tubing ends hot iron dipping ends acidsulphuric acid thinkand finally applying some sort glue letting dry ajig day made very good joint still have D-VII Nieuport 27 equipped tires made method used about 25 years ago method troublesome problems using tubing aside joining getting proper size needed sort eliminates ti work rang simp rubb maki stanc noi stick get tI Ih desci scale mak dime ted swee c easy tube X teles hobt Ye much use w years ago stumbled way make res exactly like wanted method has d fine sizes have done far 1 inch OD 3 OD Very y put tire material used silicone r tire mold plaster ofparis After ig number different tires have sort ardized procedure Although method 100% foolproof tire sometimes mold may quite fill out ie size type want ye selected WW type tire subject the method step-by-step one-inch tire will 2 outside diameter cross section diameter first step tire template Fig 1 shows idea risions template template rotathe tube bearing plaster mold ps out groove tire use brass mponents mainly because rust-proof work solders well rass shaft template fits 9/32 OD OD brass tube bearing mold oping tubes readily available y stores i will note tire template bstitute funny looking wheels otherwise perfect scale job consider making own Pre WW WW II the2Os and3Os installment author describes making tires up 2 diameter Next month really gets rolling anysize tires mak ing wheels go themup 7114-in di ameterE shown located 15/16 r shaft centerline 1/16 less one-in radius true scale size have found advisable make tires somewhat under sized will snug tight wheel Exact size tires come off fairly easily unless glued can happen tire mounted its wheel will proper diameter top side arm opposite tire template shown two small templates about 1/16 r templates will cut overfill grooves shaft ends reversed recommended templates soldered sweep arm first arm located notched shaft tube proper lo cation square tube See Fig 1-A assortment templates mating tubes bearing mold must 36 Model Aviation 1 square surface mold arm template can rotate plane mold surface reasonably well two ways install bearing First allow mold cure out several days drill hole bearing tubes drill press thus insuring vertical hole must careful use 9/32 drill 9/32 OD bearing because drill will make oversize hole plaster causing very sloppy fit Try l ream good fit Glue bearing tube place using white glue Hot Stuff plaster dry enough method airight use small tires since amount hard dry plaster too great scrape out can problem bigger tires impossible large sizes say 3 inches up cast bearing place mold poured Also larger sizes have found advisable begin sweeping grooves shortly after has set few minutes after shapes lay fiberglass inside produce cowls etc like have couple ofpails water handy keep templates clean hands free plaster working As things good practice improves experience Now know something about pre liminary requirements have hand template bearing frame plus plaster water ready mix can start make mold Place mold bearing pin support mold frame shown Fig 4 Place frame sheet glass preferably e secure place weights modeling clay glass will give flat smooth surface sweep grooves Spray glass surface Pam silicone before pouring will prevent plaster sticking next step consists mixing plaster described before pouring mold pour made 1 plaster time ancs next five minutes hard like sort firm mush very easily scraped cannot support bearing unless bearing has arms soldered will serve prevent bearing rotating well stabilizing vertically careful handling necessary Fig 2 shows bearing wire arms sometimes use coat-hangar wire really too big handy cast-in bearing located place n extends up through hole piece wood drilled drill press squareness wood piece can lightly tacked mold frame held place weights during plaster pour Remove wood pin plaster has set mold frame material use whatever scrap wood have hand can 1A plywood thicker white pine spruce mold nailed together two nails joint Use small diameter nails joints can knocked apart easily remove mold Fig 3 shows approximate size frame 2 OD tire Since molds made plaster better take moment leam something Technically plaster ofparis primarily calcium sulphate CASO4 made heating grinding gypsum rock has certain chemicals added special uses US Gypsum Company produces several types art plaster casting plaster hydrocal hydrostone progressively harder art casting plasters fairly similar can used molds Hydrocal much harder cured difficult work expensive times have used mixture art plaster hydrocal needed harder mold would last longer art plaster mold Some care required mixing plaster wish scientific about big boys say calculate weight water full mold will contain measure out plaster weigh same water Now pour off r remaining water put mixing bowl plaster gently sifted slowly added water Let mixture soak about minute stir Note plaster about 1/16 below water surface about right add water plaster get ap proximately 1/16 before mixing after Proceed mix using hand spoon paddle After about four minutes will notice beginning thicken indication pour mold frame weigh out water plaster calculate volume mold fill bowl me done above However instead weighing plaster sift water until island appears water surface island plaster slowly melts down add little until less remains submerges bowl tapped few times method roughly gives about 1/16 water layer over plasteras first method eliminates requirement scale Plaster can mixed less water plaster will stronger mix Conversely thinner mix will yield weaker plaster dried Out cured Working plaster may new modelers Its possibilities good way take molds off wood plaster fingers bring bubbles top As liquid starts thicken overfill slightly let plaster set few minutes plaster firm gently remove bearing pin support pin being careful disturb bearing because plaster although set hard Strike off excess plaster straightedge flush frame Next need invert mold can cut grooves smooth side may bit troublesome get plaster off glass can usually slide offdue prior spray job silicone Now can sweep grooves Take care disturb groove edges may notice time plaster getting hot normal Just chemical reaction taking place Once tire groove cleaned out its full depth reverse shaft cut two overfill grooves Later mold fully cured cut fill connecting slots can about size automatic pencil lead Space about ughly 12 spaces After finishing grooving remove frame clean up reassemble make other half mold same manner Let molds cure out about week fully dried will sound like metal tapped hard object material used tire silicone rubber various brands silicone rubber caulk seal material available Most experience has General Electrics brand first used GEs black Silicone Glue Seal comes 3-oz tube available hardware stores isnt exactly cheap February 1980 37 thing dislike about tube has rolled like toothpaste get gunk out As result its difficult produce nice steady flow desirable Another material GEs Silicone Rubber caulk packaged about 1 l-oz cartridge requires ordinary caulking gun apply caulk material about half cost seal material per unit volume dont know cost difference due volume 3 ounce versus 11 ounce whether its content differ ence cannot distinguish except possible exception seal may cure faster caulk molds dry ready try first tire prepare having alignment pin ready pin lines up mold its bearing like axle Have couple C clamps ready well some plywood backs molds Before laying rubber spray mold silicone spray Give couple coats since soaks plaster pretty well Whichever rubber material opt use fill mold its full level best can judge Try fill groove full first pass pushing material out ahead nozzle no air trapped under material careful come back starting point no air trapped juncture Trapped air leaves nice dent finished tire causes loud gnashing teeth dire mutterings mayhem author least stuff isnt too easy smooth over though wet spatula works somewhat Try add tad fill some overflow will occur prevent starved tire groove filling operation sort guess job best remember too much better enough After filling grooves insert alignment pin mold slide other mold Bring molds almost together say within 1 / 16 rotate other back forth s sort wring together Dont worry gap remains Clamp together wood backs see Fig 5 place damage plaster Dont use too much pressure few minutes snug up clamps again satisfied molds fully together leave alone used seal material open mold about 10-12 hours caulk used wait about 24 hours safe-side times opening molds get clamps backs off remove aligning pin first important because case sticking problem halves may parallel molds parting Separate using wooden shallow angle wedges hammer work carefully Sometimes Ive sticking problem half tire would stuck mold other half other mold Forcing looking may damage tire molds separated study result Note amount overfill etc Remove tire look trapped air dents Trim off flash brush clean suede brass bristle brush Brushing under running water also cleans up nicely ready tire number two dont forget spray molds again before laying rubber tire has dent some sort imperfection may filled same silicone material working care fully repair will noticeable pretty well describes basic method silicone rubber tire making will note material does require heat cure out does need air moisture plaster porous enough supply need material will set up metal mold plastic Small tire sizes up 2 d just discussed suitable rubber power small engine jobs Models larger begin weigh pound two up will naturally have larger tires will need stronger wheels mount continued March issue lifted pictures Part II provide Impression ot typical range tire sizes including 7% inches diameter Right scale 7-in wheel tire classic quarter-scaler 30 5 wheel ended up ye eds big Aristocratoh joy 38 Model Aviation Fig 5 mold clamped up Note use plywood prevent damage plaster well spreading load clamping force
Edition: Model Aviation - 1980/02
Page Numbers: 36, 37, 38
Harry C Shoaf ONE OF frustrating problems scale modeler often faces locating making proper wheel tireespecially tire would seem now wheel manufacturing companies would have complete line kinds sizes True can find fair selection air-wheel types few others like pre- World War World War 20s 30s wonder pet model areas WW flying scale usually around 1 inch ot Years ago thought ng people would surely have sizes wanted No luck tire diameter right section size would too thin usually ended up er tubing lousy joint using slug dowel finally discovered good joining method however consisted searing tubing ends hot iron dipping ends acidsulphuric acid thinkand finally applying some sort glue letting dry ajig day made very good joint still have D-VII Nieuport 27 equipped tires made method used about 25 years ago method troublesome problems using tubing aside joining getting proper size needed sort eliminates ti work rang simp rubb maki stanc noi stick get tI Ih desci scale mak dime ted swee c easy tube X teles hobt Ye much use w years ago stumbled way make res exactly like wanted method has d fine sizes have done far 1 inch OD 3 OD Very y put tire material used silicone r tire mold plaster ofparis After ig number different tires have sort ardized procedure Although method 100% foolproof tire sometimes mold may quite fill out ie size type want ye selected WW type tire subject the method step-by-step one-inch tire will 2 outside diameter cross section diameter first step tire template Fig 1 shows idea risions template template rotathe tube bearing plaster mold ps out groove tire use brass mponents mainly because rust-proof work solders well rass shaft template fits 9/32 OD OD brass tube bearing mold oping tubes readily available y stores i will note tire template bstitute funny looking wheels otherwise perfect scale job consider making own Pre WW WW II the2Os and3Os installment author describes making tires up 2 diameter Next month really gets rolling anysize tires mak ing wheels go themup 7114-in di ameterE shown located 15/16 r shaft centerline 1/16 less one-in radius true scale size have found advisable make tires somewhat under sized will snug tight wheel Exact size tires come off fairly easily unless glued can happen tire mounted its wheel will proper diameter top side arm opposite tire template shown two small templates about 1/16 r templates will cut overfill grooves shaft ends reversed recommended templates soldered sweep arm first arm located notched shaft tube proper lo cation square tube See Fig 1-A assortment templates mating tubes bearing mold must 36 Model Aviation 1 square surface mold arm template can rotate plane mold surface reasonably well two ways install bearing First allow mold cure out several days drill hole bearing tubes drill press thus insuring vertical hole must careful use 9/32 drill 9/32 OD bearing because drill will make oversize hole plaster causing very sloppy fit Try l ream good fit Glue bearing tube place using white glue Hot Stuff plaster dry enough method airight use small tires since amount hard dry plaster too great scrape out can problem bigger tires impossible large sizes say 3 inches up cast bearing place mold poured Also larger sizes have found advisable begin sweeping grooves shortly after has set few minutes after shapes lay fiberglass inside produce cowls etc like have couple ofpails water handy keep templates clean hands free plaster working As things good practice improves experience Now know something about pre liminary requirements have hand template bearing frame plus plaster water ready mix can start make mold Place mold bearing pin support mold frame shown Fig 4 Place frame sheet glass preferably e secure place weights modeling clay glass will give flat smooth surface sweep grooves Spray glass surface Pam silicone before pouring will prevent plaster sticking next step consists mixing plaster described before pouring mold pour made 1 plaster time ancs next five minutes hard like sort firm mush very easily scraped cannot support bearing unless bearing has arms soldered will serve prevent bearing rotating well stabilizing vertically careful handling necessary Fig 2 shows bearing wire arms sometimes use coat-hangar wire really too big handy cast-in bearing located place n extends up through hole piece wood drilled drill press squareness wood piece can lightly tacked mold frame held place weights during plaster pour Remove wood pin plaster has set mold frame material use whatever scrap wood have hand can 1A plywood thicker white pine spruce mold nailed together two nails joint Use small diameter nails joints can knocked apart easily remove mold Fig 3 shows approximate size frame 2 OD tire Since molds made plaster better take moment leam something Technically plaster ofparis primarily calcium sulphate CASO4 made heating grinding gypsum rock has certain chemicals added special uses US Gypsum Company produces several types art plaster casting plaster hydrocal hydrostone progressively harder art casting plasters fairly similar can used molds Hydrocal much harder cured difficult work expensive times have used mixture art plaster hydrocal needed harder mold would last longer art plaster mold Some care required mixing plaster wish scientific about big boys say calculate weight water full mold will contain measure out plaster weigh same water Now pour off r remaining water put mixing bowl plaster gently sifted slowly added water Let mixture soak about minute stir Note plaster about 1/16 below water surface about right add water plaster get ap proximately 1/16 before mixing after Proceed mix using hand spoon paddle After about four minutes will notice beginning thicken indication pour mold frame weigh out water plaster calculate volume mold fill bowl me done above However instead weighing plaster sift water until island appears water surface island plaster slowly melts down add little until less remains submerges bowl tapped few times method roughly gives about 1/16 water layer over plasteras first method eliminates requirement scale Plaster can mixed less water plaster will stronger mix Conversely thinner mix will yield weaker plaster dried Out cured Working plaster may new modelers Its possibilities good way take molds off wood plaster fingers bring bubbles top As liquid starts thicken overfill slightly let plaster set few minutes plaster firm gently remove bearing pin support pin being careful disturb bearing because plaster although set hard Strike off excess plaster straightedge flush frame Next need invert mold can cut grooves smooth side may bit troublesome get plaster off glass can usually slide offdue prior spray job silicone Now can sweep grooves Take care disturb groove edges may notice time plaster getting hot normal Just chemical reaction taking place Once tire groove cleaned out its full depth reverse shaft cut two overfill grooves Later mold fully cured cut fill connecting slots can about size automatic pencil lead Space about ughly 12 spaces After finishing grooving remove frame clean up reassemble make other half mold same manner Let molds cure out about week fully dried will sound like metal tapped hard object material used tire silicone rubber various brands silicone rubber caulk seal material available Most experience has General Electrics brand first used GEs black Silicone Glue Seal comes 3-oz tube available hardware stores isnt exactly cheap February 1980 37 thing dislike about tube has rolled like toothpaste get gunk out As result its difficult produce nice steady flow desirable Another material GEs Silicone Rubber caulk packaged about 1 l-oz cartridge requires ordinary caulking gun apply caulk material about half cost seal material per unit volume dont know cost difference due volume 3 ounce versus 11 ounce whether its content differ ence cannot distinguish except possible exception seal may cure faster caulk molds dry ready try first tire prepare having alignment pin ready pin lines up mold its bearing like axle Have couple C clamps ready well some plywood backs molds Before laying rubber spray mold silicone spray Give couple coats since soaks plaster pretty well Whichever rubber material opt use fill mold its full level best can judge Try fill groove full first pass pushing material out ahead nozzle no air trapped under material careful come back starting point no air trapped juncture Trapped air leaves nice dent finished tire causes loud gnashing teeth dire mutterings mayhem author least stuff isnt too easy smooth over though wet spatula works somewhat Try add tad fill some overflow will occur prevent starved tire groove filling operation sort guess job best remember too much better enough After filling grooves insert alignment pin mold slide other mold Bring molds almost together say within 1 / 16 rotate other back forth s sort wring together Dont worry gap remains Clamp together wood backs see Fig 5 place damage plaster Dont use too much pressure few minutes snug up clamps again satisfied molds fully together leave alone used seal material open mold about 10-12 hours caulk used wait about 24 hours safe-side times opening molds get clamps backs off remove aligning pin first important because case sticking problem halves may parallel molds parting Separate using wooden shallow angle wedges hammer work carefully Sometimes Ive sticking problem half tire would stuck mold other half other mold Forcing looking may damage tire molds separated study result Note amount overfill etc Remove tire look trapped air dents Trim off flash brush clean suede brass bristle brush Brushing under running water also cleans up nicely ready tire number two dont forget spray molds again before laying rubber tire has dent some sort imperfection may filled same silicone material working care fully repair will noticeable pretty well describes basic method silicone rubber tire making will note material does require heat cure out does need air moisture plaster porous enough supply need material will set up metal mold plastic Small tire sizes up 2 d just discussed suitable rubber power small engine jobs Models larger begin weigh pound two up will naturally have larger tires will need stronger wheels mount continued March issue lifted pictures Part II provide Impression ot typical range tire sizes including 7% inches diameter Right scale 7-in wheel tire classic quarter-scaler 30 5 wheel ended up ye eds big Aristocratoh joy 38 Model Aviation Fig 5 mold clamped up Note use plywood prevent damage plaster well spreading load clamping force
Edition: Model Aviation - 1980/02
Page Numbers: 36, 37, 38
Harry C Shoaf ONE OF frustrating problems scale modeler often faces locating making proper wheel tireespecially tire would seem now wheel manufacturing companies would have complete line kinds sizes True can find fair selection air-wheel types few others like pre- World War World War 20s 30s wonder pet model areas WW flying scale usually around 1 inch ot Years ago thought ng people would surely have sizes wanted No luck tire diameter right section size would too thin usually ended up er tubing lousy joint using slug dowel finally discovered good joining method however consisted searing tubing ends hot iron dipping ends acidsulphuric acid thinkand finally applying some sort glue letting dry ajig day made very good joint still have D-VII Nieuport 27 equipped tires made method used about 25 years ago method troublesome problems using tubing aside joining getting proper size needed sort eliminates ti work rang simp rubb maki stanc noi stick get tI Ih desci scale mak dime ted swee c easy tube X teles hobt Ye much use w years ago stumbled way make res exactly like wanted method has d fine sizes have done far 1 inch OD 3 OD Very y put tire material used silicone r tire mold plaster ofparis After ig number different tires have sort ardized procedure Although method 100% foolproof tire sometimes mold may quite fill out ie size type want ye selected WW type tire subject the method step-by-step one-inch tire will 2 outside diameter cross section diameter first step tire template Fig 1 shows idea risions template template rotathe tube bearing plaster mold ps out groove tire use brass mponents mainly because rust-proof work solders well rass shaft template fits 9/32 OD OD brass tube bearing mold oping tubes readily available y stores i will note tire template bstitute funny looking wheels otherwise perfect scale job consider making own Pre WW WW II the2Os and3Os installment author describes making tires up 2 diameter Next month really gets rolling anysize tires mak ing wheels go themup 7114-in di ameterE shown located 15/16 r shaft centerline 1/16 less one-in radius true scale size have found advisable make tires somewhat under sized will snug tight wheel Exact size tires come off fairly easily unless glued can happen tire mounted its wheel will proper diameter top side arm opposite tire template shown two small templates about 1/16 r templates will cut overfill grooves shaft ends reversed recommended templates soldered sweep arm first arm located notched shaft tube proper lo cation square tube See Fig 1-A assortment templates mating tubes bearing mold must 36 Model Aviation 1 square surface mold arm template can rotate plane mold surface reasonably well two ways install bearing First allow mold cure out several days drill hole bearing tubes drill press thus insuring vertical hole must careful use 9/32 drill 9/32 OD bearing because drill will make oversize hole plaster causing very sloppy fit Try l ream good fit Glue bearing tube place using white glue Hot Stuff plaster dry enough method airight use small tires since amount hard dry plaster too great scrape out can problem bigger tires impossible large sizes say 3 inches up cast bearing place mold poured Also larger sizes have found advisable begin sweeping grooves shortly after has set few minutes after shapes lay fiberglass inside produce cowls etc like have couple ofpails water handy keep templates clean hands free plaster working As things good practice improves experience Now know something about pre liminary requirements have hand template bearing frame plus plaster water ready mix can start make mold Place mold bearing pin support mold frame shown Fig 4 Place frame sheet glass preferably e secure place weights modeling clay glass will give flat smooth surface sweep grooves Spray glass surface Pam silicone before pouring will prevent plaster sticking next step consists mixing plaster described before pouring mold pour made 1 plaster time ancs next five minutes hard like sort firm mush very easily scraped cannot support bearing unless bearing has arms soldered will serve prevent bearing rotating well stabilizing vertically careful handling necessary Fig 2 shows bearing wire arms sometimes use coat-hangar wire really too big handy cast-in bearing located place n extends up through hole piece wood drilled drill press squareness wood piece can lightly tacked mold frame held place weights during plaster pour Remove wood pin plaster has set mold frame material use whatever scrap wood have hand can 1A plywood thicker white pine spruce mold nailed together two nails joint Use small diameter nails joints can knocked apart easily remove mold Fig 3 shows approximate size frame 2 OD tire Since molds made plaster better take moment leam something Technically plaster ofparis primarily calcium sulphate CASO4 made heating grinding gypsum rock has certain chemicals added special uses US Gypsum Company produces several types art plaster casting plaster hydrocal hydrostone progressively harder art casting plasters fairly similar can used molds Hydrocal much harder cured difficult work expensive times have used mixture art plaster hydrocal needed harder mold would last longer art plaster mold Some care required mixing plaster wish scientific about big boys say calculate weight water full mold will contain measure out plaster weigh same water Now pour off r remaining water put mixing bowl plaster gently sifted slowly added water Let mixture soak about minute stir Note plaster about 1/16 below water surface about right add water plaster get ap proximately 1/16 before mixing after Proceed mix using hand spoon paddle After about four minutes will notice beginning thicken indication pour mold frame weigh out water plaster calculate volume mold fill bowl me done above However instead weighing plaster sift water until island appears water surface island plaster slowly melts down add little until less remains submerges bowl tapped few times method roughly gives about 1/16 water layer over plasteras first method eliminates requirement scale Plaster can mixed less water plaster will stronger mix Conversely thinner mix will yield weaker plaster dried Out cured Working plaster may new modelers Its possibilities good way take molds off wood plaster fingers bring bubbles top As liquid starts thicken overfill slightly let plaster set few minutes plaster firm gently remove bearing pin support pin being careful disturb bearing because plaster although set hard Strike off excess plaster straightedge flush frame Next need invert mold can cut grooves smooth side may bit troublesome get plaster off glass can usually slide offdue prior spray job silicone Now can sweep grooves Take care disturb groove edges may notice time plaster getting hot normal Just chemical reaction taking place Once tire groove cleaned out its full depth reverse shaft cut two overfill grooves Later mold fully cured cut fill connecting slots can about size automatic pencil lead Space about ughly 12 spaces After finishing grooving remove frame clean up reassemble make other half mold same manner Let molds cure out about week fully dried will sound like metal tapped hard object material used tire silicone rubber various brands silicone rubber caulk seal material available Most experience has General Electrics brand first used GEs black Silicone Glue Seal comes 3-oz tube available hardware stores isnt exactly cheap February 1980 37 thing dislike about tube has rolled like toothpaste get gunk out As result its difficult produce nice steady flow desirable Another material GEs Silicone Rubber caulk packaged about 1 l-oz cartridge requires ordinary caulking gun apply caulk material about half cost seal material per unit volume dont know cost difference due volume 3 ounce versus 11 ounce whether its content differ ence cannot distinguish except possible exception seal may cure faster caulk molds dry ready try first tire prepare having alignment pin ready pin lines up mold its bearing like axle Have couple C clamps ready well some plywood backs molds Before laying rubber spray mold silicone spray Give couple coats since soaks plaster pretty well Whichever rubber material opt use fill mold its full level best can judge Try fill groove full first pass pushing material out ahead nozzle no air trapped under material careful come back starting point no air trapped juncture Trapped air leaves nice dent finished tire causes loud gnashing teeth dire mutterings mayhem author least stuff isnt too easy smooth over though wet spatula works somewhat Try add tad fill some overflow will occur prevent starved tire groove filling operation sort guess job best remember too much better enough After filling grooves insert alignment pin mold slide other mold Bring molds almost together say within 1 / 16 rotate other back forth s sort wring together Dont worry gap remains Clamp together wood backs see Fig 5 place damage plaster Dont use too much pressure few minutes snug up clamps again satisfied molds fully together leave alone used seal material open mold about 10-12 hours caulk used wait about 24 hours safe-side times opening molds get clamps backs off remove aligning pin first important because case sticking problem halves may parallel molds parting Separate using wooden shallow angle wedges hammer work carefully Sometimes Ive sticking problem half tire would stuck mold other half other mold Forcing looking may damage tire molds separated study result Note amount overfill etc Remove tire look trapped air dents Trim off flash brush clean suede brass bristle brush Brushing under running water also cleans up nicely ready tire number two dont forget spray molds again before laying rubber tire has dent some sort imperfection may filled same silicone material working care fully repair will noticeable pretty well describes basic method silicone rubber tire making will note material does require heat cure out does need air moisture plaster porous enough supply need material will set up metal mold plastic Small tire sizes up 2 d just discussed suitable rubber power small engine jobs Models larger begin weigh pound two up will naturally have larger tires will need stronger wheels mount continued March issue lifted pictures Part II provide Impression ot typical range tire sizes including 7% inches diameter Right scale 7-in wheel tire classic quarter-scaler 30 5 wheel ended up ye eds big Aristocratoh joy 38 Model Aviation Fig 5 mold clamped up Note use plywood prevent damage plaster well spreading load clamping force