spindle cross section view

[routercnc]

Hi Ross,
Sorry, that's it. I've found the original picture - scroll to post #9
http://www.cnczone.com/forums/showthread.php?t=101803

There is a model reference number in the bottom right corner of the picture, maybe search on that?

By the way, I stumbled across Steve Hilton's post from earlier this year where he was making a spindle. I notice you replied - but worth another look?

[Ross77]

Thanks Barry, this spindle thing is driving me around in circles........

Yeah I remember that, Think he already had the cartridge spindle and quality bearings, just remade the spindle for er 11 collet. cheers I will look again tho.

[coredump]

Thats the bit thats confusing me as there are plenty of designs like that but the manufactures say dont do it. The locked bearings should be at the bussiness end and free floating bearing at the other,

Deckel do the opposite: free floating (needle bearing) at the nose, locked bearings (dual andular ones) at the end. This allow very sturdy spindle with a short distance between nose and bearing (almost 0 since the needle bearing is outside the taper nose).

[Jonathan]

Deckel do the opposite: free floating (needle bearing) at the nose, locked bearings (dual andular ones) at the end. This allow very sturdy spindle with a short distance between nose and bearing (almost 0 since the needle bearing is outside the taper nose).

I might be being pedantic, but surely as the spindle heats up the shaft will expand and push the cutter down slightly further. Clearly won't happen if the fixed bearing is near the chuck. Negligible?

[coredump]

Sure if you are milling in the micron ball park. Anyway once you spindle reach thermal equilibrium you don't care anymore about this.

Edit: to be precise, FP1 have two needle bearing outside the taper and directly behind them, a trust bearing. On the other side of the spindle, a single trust bearing.

[Ross77]

Sure if you are milling in the micron ball park. Anyway once you spindle reach thermal equilibrium you don't care anymore about this.

Fair point and and seems to be the mailn difficulty with building high speed precision spindles is getting the correct clearances at operating temp.

You did only mention axial expansion but the real problem (for a diy spindle) I think would be the radial expansion and the resulting change in bearing clearance

if its preloaded when cold it can cause brinelling problems if not used regularly and if the preload increases during the warm up period then there is the risk of overheating and to much preload binding and associated damage.

Therefore I think needle bearings would be difficult to use if mounted in the front. Btw Did you mean needle bearings or roller? as I dont think needle are suitable for high load and cant have a taper added to change the preload. Are they?

Do you have a diagram and design use for that spindle?

[Jonathan]

Surely you want angular contact bearings? I've got a spare pair FAG 7206 bearings... ABEC7 grade (so intended for spindles)! If you're interested...

You need to work it out such that the spindle temperature remains in a certain range, so etc.

[Ross77]

Cheers, yeah I do I was just trying to clarify what coredump was suggesting with the needle bearings.

I already have a matched pair of Barden precision bearings 109HDL (45mm int.) for the nose, if I can make the spindle accurattly then most of an ER 32 collet will be in side the bearing anyway. I do need some bearings for the rear but they will need to be floating or have end float, allowing them to slide on the shaft or housing just adds more maching headaches.

I intend to do a practice run first so might be intested in the bearings.what size are they,contact angle , clearance etc.

cheers

[Jonathan]

They are FAG B7206C.T.P4S.UL
The info is all on the FAG site if I recall correctly.

[coredump]

Hi,

You can find the cross view of FP1 spindle here: http://www.usinages.com/manuels-docu...fp1-t3738.html page 55 of the documentation (sorry in french).

Still in french, if you look at this thread: http://www.usinages.com/conception-f...xy-t15107.html the guy build a spindle very close from Deckel spindle (and he got one FP3, no wonder why).
His spindle is made from 42CD4 (no post treatment), BT40 spindle nose (done on an asian lathe), Needle bearing in front, runing on a bearing ring (NKI bearing), double angular bearing (normal SKF) on top.
The trick to have low radial clearance is to use the fact that needle bearing race is thin, so a very tigh adjustement make the race growing, or shrinking. In fact in his case the adjustement is a little bit on the high side. He explain me that Deckel use a wide range of needle, spaced in micron, to found the correct adjustement when building or refitting a spindle (he used to work a lot with Deckel in his professional life). There is also some growable needle bearing (INA), but more exotic.
Btw, all his epoxy granit mill has been done with pure DIY spirit: no big machines (not even his FP3, which he doesn't have at first), no exotic component. I have seen it IRL and it's pretty impressive.