AlfaGTA
Diamond
- Joined
- Dec 13, 2002
- Location
- Benicia California USA
Running a little job here that required some work around to handle the size of the needed parts.
Fitting new liners to a car set of brake drums on a 52' 340 mm Ferrari.
Originals had been worn and turned too many times where the liners had become thin and unreliable.
Original drums setup on the lathe (21" "Dong Yang" , stupid name, gorgeous license copy of an Okuma) And original steel liners cut out.
Drums cleaned up straight and round to the same size for the front and same for the smaller rear.
Material selected was Ductil iron,(80-55-06) supplied by "Dura-Bar. Sized at 14", and 15" OD's. being roughly 4 1/2" long.
Needed the material to have a center hole, but only supplied or available as a solid. Dura-Bar was able to supply the material by trepanning the center hole...Saving tons of time and
material cost.
Set the rings up on he lathe for turning. Lathe is 21" swing, but the starting material is too large to pass over the cross slide. To allow machining i used a boring bar (shop built)
to give the reach needed (over 5" long) .Design of the bar allowed turning both ID and OD by swapping the tool holder from RH (OD) to LH (ID)...
Material was purchased aprox 1 3/4" longer than required to allow for chucking. I wanted to be able to machine both the ID and OD in one setup.
Which brings us to the Deckel portion of this story.
Once the ID and OD were at size i needed to cut off the excess stock. tool long to allow use of the parting tool in a conventional setup on the lathe...
Could have ground up a parting style tool that fit the boring bar already in use, but i suspected that the depth of cut (1.3" on a side) would be difficult to handle and not really rigid.
Opted to do this operation on the FP4NC.
Took the 10" "Schunk" chuck off the Romi and fitted some extended soft jaws that would allow chucking the larger (front) liners on the ID....
Removed the cam lock pins from the chuck (D1-6) and set the chuck on the mill table. Without the pins you have in effect a flat face on the chuck back. Set the chuck in the center of the machine table
and using the rotary function set the chuck to run true with the table's rotation.....Used hold down clamps to secure the chuck body to the table....
Gripped the liner and mounted a .250" 5" diac saw to a stub arbor and i was ready to proceed.
Plunged the cutter till it pierced the inner wall of the liner, then used the rotary feature of the 2038 table to cut the unwanted stock from the liner.....
Working this way, found the best was to climb cut. Reduced the chatter and allowed relatively rapid rotation.....
Definitely not the most efficient way to get this done, but worked without issue so that i could continue with the job....
This was a case where a nice VTL (Bullard) would have been the ticket.
Another view of the job...Chuck has been changed to different jaws in order to run the smaller rear liners. Here i added some clamps to ade in holding the part...Gripping on the thin liners from the ID they tend to turn into a three lobed part and its hard to develop enough grip. Here i am clamping between the jaw of the chuck and the OD of the liner ....a more direct grip.
Clamps holding the chuck also clearly seen...Cutter is opposite side of the part , about to finish the cut....
Lots more to this job, but most involved different tools/setups that aren't relevant here....
Cheers Ross
Fitting new liners to a car set of brake drums on a 52' 340 mm Ferrari.
Originals had been worn and turned too many times where the liners had become thin and unreliable.
Original drums setup on the lathe (21" "Dong Yang" , stupid name, gorgeous license copy of an Okuma) And original steel liners cut out.
Drums cleaned up straight and round to the same size for the front and same for the smaller rear.
Material selected was Ductil iron,(80-55-06) supplied by "Dura-Bar. Sized at 14", and 15" OD's. being roughly 4 1/2" long.
Needed the material to have a center hole, but only supplied or available as a solid. Dura-Bar was able to supply the material by trepanning the center hole...Saving tons of time and
material cost.
Set the rings up on he lathe for turning. Lathe is 21" swing, but the starting material is too large to pass over the cross slide. To allow machining i used a boring bar (shop built)
to give the reach needed (over 5" long) .Design of the bar allowed turning both ID and OD by swapping the tool holder from RH (OD) to LH (ID)...
Material was purchased aprox 1 3/4" longer than required to allow for chucking. I wanted to be able to machine both the ID and OD in one setup.
Which brings us to the Deckel portion of this story.
Once the ID and OD were at size i needed to cut off the excess stock. tool long to allow use of the parting tool in a conventional setup on the lathe...
Could have ground up a parting style tool that fit the boring bar already in use, but i suspected that the depth of cut (1.3" on a side) would be difficult to handle and not really rigid.
Opted to do this operation on the FP4NC.
Took the 10" "Schunk" chuck off the Romi and fitted some extended soft jaws that would allow chucking the larger (front) liners on the ID....
Removed the cam lock pins from the chuck (D1-6) and set the chuck on the mill table. Without the pins you have in effect a flat face on the chuck back. Set the chuck in the center of the machine table
and using the rotary function set the chuck to run true with the table's rotation.....Used hold down clamps to secure the chuck body to the table....
Gripped the liner and mounted a .250" 5" diac saw to a stub arbor and i was ready to proceed.
Plunged the cutter till it pierced the inner wall of the liner, then used the rotary feature of the 2038 table to cut the unwanted stock from the liner.....
Working this way, found the best was to climb cut. Reduced the chatter and allowed relatively rapid rotation.....
Definitely not the most efficient way to get this done, but worked without issue so that i could continue with the job....
This was a case where a nice VTL (Bullard) would have been the ticket.
Another view of the job...Chuck has been changed to different jaws in order to run the smaller rear liners. Here i added some clamps to ade in holding the part...Gripping on the thin liners from the ID they tend to turn into a three lobed part and its hard to develop enough grip. Here i am clamping between the jaw of the chuck and the OD of the liner ....a more direct grip.
Clamps holding the chuck also clearly seen...Cutter is opposite side of the part , about to finish the cut....
Lots more to this job, but most involved different tools/setups that aren't relevant here....
Cheers Ross