SAE-8 Banjo Fitting Autocad
- Thread starter tomrscott
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Then I used a center drill to mark the center of the first port sleeve, and drilled it with an 1/8", 1/4", .406", and .5" drills. The first three drills I drilled through to what will be the core of the banjo, but with the 1/2" drill I stopped at 1/2" depth to make a shoulder to stop the tubing.
The profile radiusing is almost impossible to get very smooth by hand. I just don't the proper trig calibration in my hands to CNC it manually. /forums/images/graemlins/smirk.gif The last thing you want to do is to cut too far, so I left it a little big. I will be cutting a similar radius profile at a right angle to this which will allow me to take some of the roughness out.
/forums/images/graemlins/smirk.gif
The profile radiusing is almost impossible to get very smooth by hand. I just don't the proper trig calibration in my hands to CNC it manually. /forums/images/graemlins/smirk.gif The last thing you want to do is to cut too far, so I left it a little big. I will be cutting a similar radius profile at a right angle to this which will allow me to take some of the roughness out.
/forums/images/graemlins/smirk.gif
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I forgot to take shots of cutting the second port, but of course that would have looked just about like the first port. I got kind of distracted because I had gotten impatient and fed the starting 1/8" drill too fast and snapped it off. Steel is pretty unforgiving of impatience. Anyway, it was just the very tip and I was able to drill past it with the through hole and then push it out with a drift punch (ie: I got lucky).
This shot shows the piece turned flat so I can face it, and drill the 3/4" through hole. I set the piece as flat in the chuck as I could get it, and then cut a clean face. Then center drilled the piece, drilled with an 1/8" starter drill, 1/4", 3/8" 1/2", 5/8", and finally a 3/4". I did a bit of deburring and here it is.
/forums/images/graemlins/smirk.gif
This shot shows the piece turned flat so I can face it, and drill the 3/4" through hole. I set the piece as flat in the chuck as I could get it, and then cut a clean face. Then center drilled the piece, drilled with an 1/8" starter drill, 1/4", 3/8" 1/2", 5/8", and finally a 3/4". I did a bit of deburring and here it is.
/forums/images/graemlins/smirk.gif
Attachments
In this shot you can see that I decided to put some stubby bolts in the braze sleeves to spread out the chuck jaw pressure. With the violence of boring a 3/4" hole, I had to clamp down the chuck jaws real tight and it would have left deep impressions on the braze sleeve ends. This way they came out without a scratch.
This shot is a bit misleading. It looks like the profiling is about done, but the far corners are still pretty rough and will get profiled more in another setup.
/forums/images/graemlins/smirk.gif
This shot is a bit misleading. It looks like the profiling is about done, but the far corners are still pretty rough and will get profiled more in another setup.
/forums/images/graemlins/smirk.gif
Attachments
Finally a quick deburr with the tool bit that I used to face the piece (forgot to shoot that process).
I've left the whole body a bit oversize on purpose. I can cut it down if I want to later, but I was thinking that since this is a two port banjo, maybe I'd make it a bit oversize inside for increased flow. I would rather cut the inside bore first and leave a little extra beef for now.
I am not trying to follow the print exactly, but having the print handy keeps me from overcutting and it is real hard to "cut it bigger."
/forums/images/graemlins/smirk.gif
I've left the whole body a bit oversize on purpose. I can cut it down if I want to later, but I was thinking that since this is a two port banjo, maybe I'd make it a bit oversize inside for increased flow. I would rather cut the inside bore first and leave a little extra beef for now.
I am not trying to follow the print exactly, but having the print handy keeps me from overcutting and it is real hard to "cut it bigger."
/forums/images/graemlins/smirk.gif
