Grinding a spindle taper. ( First time)

I have a spindle problem. Cat 40. Cincinnati arrow 1000. I will attempt to re-grind the taper. Looking in the catalog for a suitable wheel, I found this:
http://www1.mscdirect.com/eCommerce/NavigationServlet/Abrasives/Grinding-Cutoff/Grinding-Cutoff-Wheels/Internal-Grinding-Wheels/_/N-77chp?refinementB92403719&searchandizedOk=Y
MSC Item #: 78708088
I was trying to find a wheel that would fit my tool post grinder, and there were two choices.. I ordered a few of each.
The plan is to tear the draw bar and retaining balls out. Cheat the limit switches to allow it to run, align everything, and use the axes to grind the taper.
It seems straightforward. The taper certainly NEEDS to be fixed. It was worn when I got it, and since that machine does not get the high tolerance work, I was living with it, for a as long as possible. The time has come to come to the aid of the spindle taper.
I tried to blue the spindle with a fairly new toolholder, and the bluing pattern I got matches what I am seeing in the taper.
OK, Flame away!
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http://www1.mscdirect.com/eCommerce/NavigationServlet/Abrasives/Grinding-Cutoff/Grinding-Cutoff-Wheels/Internal-Grinding-Wheels/_/N-77chp?refinementB92403719&searchandizedOk=Y
No flames but
Generally speaking, much better to remove the spindle and fixture it, using a stand alone slide that's been angled at the proper taper what is it like 3.5 in per foot IIRC instead of your expecting to obtain an accurate result by interpolating xz or yz slides at the machine tool
--the reality here is if you are using the xz slides, the best you can hope for is a "stairstep"...whereas it takes a certain amopunt over so many .0001 counts tally in order for another count to be applied in the other axis's motion profile.
That said, you might do well to program an overshoot in your "stroke_...1/2 in or so on each end would be nice, in case your servos tend to arrive at a different time and if following error is whacked ( common esp with Z...also, suggest crown your wheel, later hand lapping with a cat 40 "cleaning tool" or similar.
--








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it will be helpful if your controller can output "following error" to a screen--allowing you to test your program in advance, and to subsequently set amplifier gains so that actual error count is an equal vector in relation to both axis that you are trying to _trace_
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On Apr 29, 10:07 pm, "PrecisionmachinisT"

It should be better with a separate slide. Others have one this, this way before, and it will be a BIG improvement over how it is now.
As far as going 1/2" over, the small end will not have that much clearance. The small end of the taper is near .9" Diameter or so.
Going slow, should reduce the following error.... Sometimes you do what you feel you have to.
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Preserving
And sometmes, if your lucky and it so happened that you asked the right people--you find out just in the nick of time that it's not something that you really needed to do.
--





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On Apr 30, 1:00 am, "PrecisionmachinisT"

Well with a little bit of help and local adult supervision I got the spindle ground. Spotting shows 80 to 100 points per inch.
The wheel I asked about in the OP was useless for the spindle. Luckily next door is a large shop, that does a TON of internal grinding. I called the grinding supervisor, to ask for a recommendation for a wheel.. He literally Ran over, and brought me a Borozon wheel. YIKES!! That worked sweet! They were very helpful, actually three guys came over to see what I was up to, and offer help.
Another friend of mine has been repairing machine tools for many years, and he just kept saying Wow! The spotting pattern looked to be about perfect from his point of view.
Only glitch is the big nut on top of the stack of belleville washers, it has nylon locking pads, and they are not cooperating..... Grrrr.....
Thanks to everyone for the help! It is good to have friends. And to help out when you can.
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On Fri, 29 Apr 2011 20:24:09 -0700 (PDT), Cross-Slide

Going *real* slow - like creep grinding - is probably your best option. A single run should do the trick. Dress the wheel using the machine control (the taper is 3.5" in12" = 8.297° from centerline) and make sure the wheel is on center with the spindle or you'll end up with a curved surface.
--

-JN-

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Curious, what are you seeing, what is the condition? Condition of Spindle bearings and Draw bar force?
..............
http://www.practicalmachinist.com/vb/cnc-machining/lapping-spindle-taper-120483/
"We use a guy named Frank from CSP. This guy is damn good and fast. He grinds any spindle in the machine. I've had holders that let loose and bell mouthed the opening and welded itself to the small end of the spindle. He came in and fixed it in under an hour and had less then . 0001 runout on a 12" test bar. I back this guy and recommend him to anybody."
"He charges $600 per spindle with a (2) spindle minimum. Even if you only needed one spindle done and paid for two, its still a crap load cheaper than it would cost to do otherwise plus the added downtime."
"He used to charge a $200 trip charge. No room and board needed."
I think this the company referred to, main location Bend, Oregon:
http://spindlegrinder.com /
Even if you don't use them they have some helpful information on their site. ...............
"WE have used a toolpost grinder on the machine table to grind in a taper. Program the CNC to the angle. The key things are to make sure the machine is level and square with the world before you start, and creep up on it a tenth at a time, if it appears that there is going to be more then a few tenths metal removal, you probably have a problem you can't fix. We have done #40 & #50 CAT on HMC and VMC machiines. We have our toolmaker and CNC programmer do the work. It's not a job for the shop newbie."
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On Fri, 29 Apr 2011 19:36:51 -0700 (PDT), Cross-Slide

What about heat from grinding? Cold air gun? shop vac sucking through top of spindle to pull air + grit up and out?
Heat might distort the taper.
Just my .02
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