[Newbie] Spindle Taper Grinding-?diy

B

Bob V

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Hi,
I'm just getting my old Van Norman running-- my first metal working machine.

I have leveled the machine.
Then I checked the spindle for perpendicular to table, and runout.
The runout was checked with a dial gauge on a magnetic arm holder and I found about .005-.007 runout on each of three different tools in the drawbar. When I checked the spindle with the indicator, I got less than .001 runout-
--So, it seems to me (I could easily be wrong-- that's why I need you guys advice!) that there may be burrs in the female 5V van Norman taper up in the spindle. Some of the tools I inherited with the mill are quite rough, and seem to me could have produced a burr in the spindle taper to cause the tooling to be out of round. --does this ever happen? (its a 1940's machine).
How can this be fixed? Is this something I can do myself? Would I have to take off the spindle head?
--How does this work? (If you guys agree this is the problem!).
Thanks in advance,
Bob
 
If the problem is in the taper the maximum runout will always show up at the same point on the spindle. Does it? Have you stuck your finger up there and felt around?
 
Anything is possible. A visual inspection would be in order before doing anything. The problem may be in the tool holders and not the spindle. A flashlight and a mirror might be useful. Or Harbor Freight sells a reasonably decent inspection camera.

Regrinding a spindle on a mill requires pretty high precision and normally should be done in the spindle bearings when possible. Some creativity might allow you to grind the taper if you can come up with a way to feed the wheel into the taper at the correct angle and keep the wheel ridged. I'm not familiar with your mill, so I can't really comment on a method.

Another possibility would be to hand ream the taper if you can find the proper reamer.
 
Thanks,
I'll check to see if the max runout is in the same spot with all 3 tools, and see if i can feel, see a burr-
At least that will narrow it down--
 
You say you got less than .001" runout when you checked the spindle but .005 - .007 when using a tool holder. Your problem is with the tool holders not your spindle. My recommendation is you check runout using a new tool holder or one that you know runs true in another machine. Also check the spindle bore for burrs as others have suggested.

Tom S
 
Hi Bob,

JimDawson said:
Another possibility would be to hand ream the taper if you can find the proper reamer.
Click to expand...

I gotta agree with Jim, a taper reamer is an easy way to cleanup the spindle taper. An extremely light cut by hand can just skim off any burrs.

-brino
 
When I first got my Van Norman #6 I had significant runout.
Similarly it uses VN#C collets otherwise known as Hardinge 5V.
After very close inspection I learned it was a problem with burrs on the key that is fit into the spindle.
Replacing the key and carefully placing the collets cured my runout problem.
This was a huge learning curve for me as my Cincy Toolmaster vertical mill with Cincy Monoset collets is not keyed.

Daryl
MN
 
First, thanks to everyone.

Tom S, I thought the runout might be due to the tool holders, but I used 3 different ones--with the runout increasing on each tool holder the same amount the same distance down from the spindle- and since the spindle had no runout, I think it's the female 5V (or VN#C as I learned from Daryl just now!) inside the spindle. I don't have another machine to check that the tool holders are "true", but I figured with three all indicating the same runout-- that it's probably the spindle female taper--

Daryl, amazing coincidence you mentioned the small key inside the spindle since the fellow who sold me the mill gave me two spare keys and told me the key inside the spindle was "kinda rough" -- so I bet that's the problem! Seems to me if the key in the female spindle is muchroomed a bit, it couls easily cause this (just guessing).
Question: Can you tell me how to replace the key in the spindle? do I just drift it out from the external surface of the spindle and put in the new one?

JimDawson or anyone else: Question: how would I go about finding a reamer for the VN #C (Hardinge 5V) taper to use by hand if I need to clean it up?? I have some Dykekm high point on order to check if the taper has hi points.

-Sorry about all the questions-- but you guys are saving me a LOT of work by providing your knowledge.
Thanks.
Bob
 
On my #6 the keyway is drilled out and held in the spindle with a pin.
I sprayed Kroil then very gently tapped the pin out.
Try not to mangle the key as it has a funky shape which you may want to replicate (or at least mine does).

Daryl
MN
 
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