The distribution brake line block on the rear of an AD master cylinder is not available new (that I can find) so going to machine some. It is the fitting that is held to the m-c with a hollow banjo bolt. Although I use a lathe and mill on a daily basis I am NOT a trained machinist and have run into a problem. The OD of the flare seat is larger than the ID of the fitting threads so a tool to cut the seat cannot pass through the threads without cutting them away. Any suggestions ???
Last edited by coilover; Sat Jan 07 2023 03:15 PM.
Undercutting behind a thread is going to require interpolation so a CNC mill will be necessary. As for the cutting tool these guys are my go to for such applications:
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Evan
The MC on my '51 just has a single line attached to it and uses two division blocks over on the right side of the frame, one splitting front to back and another splitting to RF and LF. The one you're referring to is used on only some AD's (52 and later?) I think I may have seen them somewhere, which would be easier that machining your own. Have you looked HERE? [inlinetube.com]
I think you could cut the seat with a tool ground small enough to cut the seat and the undercut on a lathe, feeding it in parallel to the seat angle, either before or after the threads are cut.
Kevin Newest Project - 51 Chevy 3100 work truck. Photos [flickr.com] #2 - '29 Ford pickup restored from the ground up. First car '29 Ford Special Coupe Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Undercutting behind a thread is going to require interpolation so a CNC mill will be necessary. As for the cutting tool these guys are my go to for such applications:
You don't have to have a CNC for that. On a lathe it is relatively simple to use a trapezoidal cutter on a boring bar to do it. Set the angle of the blade for the angle of the seat, move it down the axis of the hole inside the threads, then bring it (radially) out at the bottom of the hole and finish the cut. Then reverse to get the cutter back out.
It takes some planning and attention to the geometry for your depth, but can be done manually by someone with moderate skills.
It would take some thought on how to do it with a mill unless you had a few extra axes to play with.
Last edited by klhansen; Thu Jan 05 2023 09:34 PM. Reason: added link
Kevin Newest Project - 51 Chevy 3100 work truck. Photos [flickr.com] #2 - '29 Ford pickup restored from the ground up. First car '29 Ford Special Coupe Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Looks like there are plunge cutters available for this. The undercut at the back is probably a thread relief groove rather than a taper that is larger than the minor thread diameter.
Evan, there is a much simpler solution that requires NO special machining. The part can be made on a drill press. Call me. Jerry
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