In article ,
Grant Erwin wrote:
Brian wrote:
If you have put new motors on BP's before, what frame and shaft size motor
is required? Different for a J-head to a varispeed head? What RPM, for
that matter
Use the same frame number as the motor it now has. When I replaced mine, I
[ ... ]
My head is a J-head, don't know anything at all about a 2J head (varispeed).
There, you get into a motor which is more specialized. I've got
a 2J head on my Series-I BOSS-3 CNC machine, and it uses a motor which
is special in at least two ways:
1) The motor is rather wider than it is long, TEFC, and on the CNC
version at least, it mounts below the head (a real pain to get
it mounted with everything else right, BTW. :-) If the motor
were on top (as it is on at least some manual vari-speed heads),
it could be longer and smaller in diameter, if it won't hit the
ceiling.
2) This one is the one which is harder to get around by mounting
the motor on top of the head. The shaft has to be large, long,
and have a long key in it. The vari-speed pulley mounts
directly onto the shaft, with the moving part sliding on a
Delrin-covered steel key. There is a nasty spring to fight to
get the whole thing together, and a spring clip to get in place
while holding the spring compressed. There is a threaded hole
in the end of the shaft (which is the same thread as the bolts
holding the cover on the head), which can be used with a square
'U'-shaped bracket with a hole through it to compress and hold
the spring while you get the circlip in place.
If you let it run too long without replacing the delrin sleeve
and the delrin-covered key, you'll wind up wearing the keyway
badly, and have difficulty varying the speed through the whole
range. If it *ever* starts making more noise -- get the
replacement sleeves and key and install them before you use it
again. Otherwise, you are out a significant amount of money to
replace the motor shaft and rotor, as well as parts of the
pulley.
Good Luck,
DoN.
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