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BP spindle key

docwilson

Cast Iron
Joined
Feb 28, 2004
Location
Macon, MO USA
How long is the spindle key in a bridgeport and is it very difficult to replace? How much length is actually needed to adequately engage the R8 tooling? Thanks
 
I'm not sure the answer to your question but the mills at my work don't have the key left. All worn out/off. The collets seem to function without the key. Hope this helps
Kuulnor
 
The spindle nose key is actually a set screw with an extended dog point. After replacing it as well as putting the backup screw behind it, put your best collet in the spindle and adjust it so the collet can be drawn upwith the proper tension on the end mill. The parts are available from J & L.
Just ask for sales, then High Quality Bridgeport parts.
 
This subject came up in a thread a few weeks back, as I recall. The conventional wisdom from quite a few members, was that this item is not needed and that in fact it could become a problem if the taper was overloaded and jammed. It seems the locating screw really does not do much and will not help hold the collett under load. Most reccommended that it be left out.
 
After going through the process of cleaning up my J-head and installing a new set-screw/key, I've come to the conclusion that the most likely reason for this 'key' is simply to make sure that the tooling always lands in the spindle with the same orientation, thus, repeatability. Although it doesn't guarantee any measure of accuracy, it does mean that any inaccuracy on the part of tooling, is always the same with respect to inaccuracy in the spindle. :rolleyes:
 
Dave,
What you wrote makes a lot of sense! I keep the Spindle Nose Keys in my 2J2 Mills and have always replaced them on every J/2J Head I've worked on if I found them missing. Collet Keys and Collets are an inexpensive throw away but if the Collet were ever to spin in the Spindle without a key it could cause expensive damage to the Spindle. To each his own!
Jim Larsen
 
if the collet wants to spin ...it will spin regardless if the key was there or not.
the only reason it will spin is
1. drawbar not tightend enough.
2. dirt on collet or in spindle taper.
3. a crash.
if the key is in it will snap it off and cause more problems.
it's there just as a help.
so that you can tighten the draw bar more easily.
Thats my conclusion.....
and it was put there mnaybe to stop people cutting there hands when tightening ....because you would have to hold the tool until it starts to grip when tightening otherwise .
I hold tooling with an old leather glove crumpled up in my hands until the endmill stops rotating in the collet and it can be just held with just the brake whilst you tighten the drawbar.
Also maybe the repeatability thing ..but this would not work with endmills direct in r8 collets only collet chucks .
all the best..mark
 
At work we remove the keys. Easier to load the collets and have never had a problem in the 24 years I have run the machines. Loosen the setscrew, remove the collar, remove the key (dogpoint setscrew) and replace the collar. Just remember not to tighten the collar too tight or it will eggshape the quill so the quill will not retract all the way.

Kevin
 








 
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