Hello,
Just picked up my new series II CNC mill, and found a "feature" that I was not told about and didn't find untill it was in my shop and paid for.
How serious is this crack?
The way I see it I have 3 options:
Do nothing and run the mill and hope it dosn't crack more.
Remove the piece and weld/braze it.
Weld it in place.
What do you think I should do?

I checked the run out and it was about .001"?
Is that an acceptable amount?
Thanks

Sorry pictures didn't show up.

I think I would just drill a small hole at the end of the crack, that should stop it spreading.
What is the runout you are talking about?
Hood

The runout was the spindle. Measured on the inside of the tool holder with the quill all the way extended.
Thanks for your help.

Is there a difference with the quill fully up? should be the same all the way so if different then maybe the crack is more serious than the pics suggest. More important test would be to extend the quill and put a DTI on the spindle and push the quill and see if there is any deflection.
Hood

Oh and for a spindle runout it is best to indicate the inside of the spindle rather than a toolholder as the toolholder itself could have the runout. You may need to remove the nut from the spindle if you cant get a DTI in there.
Hood

There was no difference in the runout when the quill was extended or not.
I was measuring on the inside of the quill with the nut removed. Sorry for the confusion, I shouldn't have said toolholder.
Is .001" bad?
It was supossed to be a rebuilt head with less than 500 hours on it.

Cant remember exactly what mine is, but I know its less than yours, think mine is 0.001 or 0.0002 but I will measure tomorrow if I remember, I should really keep a note of things like that as my head is like a seive ;)
Sounds to me like they have maybe put in new bearings but not had the spindle taper reground in these new bearings, I think that is the normal way its done but others more experienced may come back and let you know for sure.
Hood

About how much does it cost to get a head rebuilt?
Thanks

Sorry dont have a clue, never had it done. I know to get new bearings and the spindle re-ground in these new bearings costs about £250 here in the UK but I think I remember seeing it a lot cheaper in the US. If I remember correctly I think someone said there is a company that advertises on eBay that does this, might be worth a search.
Hood

OK just had a look, seems Wells Index will do it, not sure if they will supply/fit new bearings but worth asking them I think.
Heres the link to the eBay add
http://cgi.ebay.com/9-B-S-to-R-8-spindle-grinding-Wells-Index-or-Index-mill_W0QQitemZ7594441090QQihZ017QQcategoryZ25290QQssPageNameZWD1VQQrdZ1QQcmdZViewItem

Oh also make sure you ask them if they can do the 30 taper as that add is for R8

OK heres the link for the 30 taper, not sure how this would affect the closing of the Ericson system though, if you mail them make sure you tell them its a QC spindle you have.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7605631910&ssPageName=MERC_VI_ReBay_Pr4_PcY_BIN_Stores_IT

Thanks that looks like a cheap and easy fix, I will contact wells index.
Thanks

I measured my runout today, only have a metric dial that is long enough to reach into the spindle. It is graduated 0.01mm and there was hardly a flicker on the needle so I can safely say the runout is less than 0.005mm (0.0002")
Hood

That is good compared to mine. I think I will have to get it fixed.