olcarguy Posted September 29, 2009 Share Posted September 29, 2009 I need to fab a transition from 4"OD to 2.25"OD for the air supply on my new forge. Problem is I seem to be forgetting many of the tricks I have learned along the way. I have built many transitions in the past but I'll be xxxxxx if I can remember how. I know I need the circumference of each piece and lay out with dividers on a perpendicular, but thats about it. Old age sucks....new metal beater....old millwright Quote Link to comment Share on other sites More sharing options...
Glenn Posted September 29, 2009 Share Posted September 29, 2009 Lay a center line down on some paper. The length of the center line will be the length of the transition. Top of the center line make a line perpendicular to the center line and the length of the circumference of the of the 4 inch OD pipe. Bottom of the center line make a line perpendicular to the center line and the length of the circumference of the of the 2.25 inch OD pipe. Divide both circumference lines into equal segments and make tick marks at the divisions. Connect top one with bottom one, top two with bottom two, etc. Bend on the lines and see how it lines up. Transfer to metal. Be sure to add a bit beyond the circumference lines for a collar. Quote Link to comment Share on other sites More sharing options...
olcarguy Posted September 29, 2009 Author Share Posted September 29, 2009 Thanks Glenn.....I knew somebody on here would know. Roy Quote Link to comment Share on other sites More sharing options...
olcarguy Posted September 29, 2009 Author Share Posted September 29, 2009 OK Glenn. Your post got me to thinking, it jogged the memory, gave it a kick start if you will. I remember the old way I did it. Draw a straight line the length of the #1 circumference, from the centre of this line draw a line at 90 Quote Link to comment Share on other sites More sharing options...
Glenn Posted September 30, 2009 Share Posted September 30, 2009 Leave a tab to connect the sides (grin) Give the credit to Irnsrgn as he showed me how. Quote Link to comment Share on other sites More sharing options...
olcarguy Posted September 30, 2009 Author Share Posted September 30, 2009 So thank you for the extended help Irnsrng....... Quote Link to comment Share on other sites More sharing options...
Nakedanvil - Grant Sarver Posted September 30, 2009 Share Posted September 30, 2009 You can try this Quote Link to comment Share on other sites More sharing options...
WillMag Posted September 30, 2009 Share Posted September 30, 2009 Making it out of sheet is great but another way which is perfectly feasible is if you have a peice of say 3" heavy wall pipe to forge the end down in a swage and flare the other end out to the size you need. It would probably be quicker too. Quote Link to comment Share on other sites More sharing options...
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