Big_Eddy
04-28-2008, 10:35 AM
On an earlier thread - I mentioned my home made brake for bending flues. Another member had requested details, so here are some pictures.
Basic brake handles 4' material, and uses a 3" channel for the base, 3x3x1/4" angle for the pivot bar, and a 3/4" x 2" bar for the hold down. (I have an alternate hold down for normal bending of 3"x3"x1/4" angle that allows for over center bending that is shown in 2 of the 3 pictures attached).
Picture 1 shows the overall brake with the angle hold down bar in horizontal mode for over center bending of thin material.
The tricky part of making a brake is locating the pivot points correctly. I welded a pivot bracket onto the end of the bed channel, then notched out the pivot bar to clear it. I drilled a hole in the handle material first, then lined the center of the pivot bolt up exactly with the corner of the pivot bar, and welded the handle in place. I then clamped the pivot bar to the bed and used the hole in the handle as a jig to drill then tap the extension piece.
Picture 2 shows details of the pivot. Note that in this picture the angle restraining bar is installed in vertical mode which provides greater strength but limits bends to ~90 degrees.
The third picture shows a test piece of 22gauge mild steel (old water heater shell) that was bent into 1"x7" flues. A couple of the bends are not that crisp as I whipped it off quickly for this thread, but with proper positioning and a tightened restraining bar, this will bend nice tight corners. In this case I am showing the 3/4"x2" restraining bar that fits down into the bottom of the flue to bend the "up" bend. Bending flues requires the material to be flipped every 2 bends so I recommend slots in the retaining bar hold downs to allow it on and off easily.
The 3" channel was used for the base instead of another angle , to allow for the full depth of the flue to be accomodated. Otherwise each new flue would be 1/4" longer than the previous. In hindsight it might not matter as the material is flexible enough that the previous flue might be able to be "opened up" a bit to allow full insertion. An angle would be stronger for other bending, but the channel is fine for the material I have been using. I use a press brake for thicker material anyway.
Hope this is of value to others. When I start bending my flue pan, I will take pictures and share.
Basic brake handles 4' material, and uses a 3" channel for the base, 3x3x1/4" angle for the pivot bar, and a 3/4" x 2" bar for the hold down. (I have an alternate hold down for normal bending of 3"x3"x1/4" angle that allows for over center bending that is shown in 2 of the 3 pictures attached).
Picture 1 shows the overall brake with the angle hold down bar in horizontal mode for over center bending of thin material.
The tricky part of making a brake is locating the pivot points correctly. I welded a pivot bracket onto the end of the bed channel, then notched out the pivot bar to clear it. I drilled a hole in the handle material first, then lined the center of the pivot bolt up exactly with the corner of the pivot bar, and welded the handle in place. I then clamped the pivot bar to the bed and used the hole in the handle as a jig to drill then tap the extension piece.
Picture 2 shows details of the pivot. Note that in this picture the angle restraining bar is installed in vertical mode which provides greater strength but limits bends to ~90 degrees.
The third picture shows a test piece of 22gauge mild steel (old water heater shell) that was bent into 1"x7" flues. A couple of the bends are not that crisp as I whipped it off quickly for this thread, but with proper positioning and a tightened restraining bar, this will bend nice tight corners. In this case I am showing the 3/4"x2" restraining bar that fits down into the bottom of the flue to bend the "up" bend. Bending flues requires the material to be flipped every 2 bends so I recommend slots in the retaining bar hold downs to allow it on and off easily.
The 3" channel was used for the base instead of another angle , to allow for the full depth of the flue to be accomodated. Otherwise each new flue would be 1/4" longer than the previous. In hindsight it might not matter as the material is flexible enough that the previous flue might be able to be "opened up" a bit to allow full insertion. An angle would be stronger for other bending, but the channel is fine for the material I have been using. I use a press brake for thicker material anyway.
Hope this is of value to others. When I start bending my flue pan, I will take pictures and share.