Dumb question on R8 (i think) spindle

I'll disagree in re lube on collets.
Anything likely to retain chips is undesirable. I wipe every spindle taper out and each holder before insertion. A cared for R8 draw bar should literally spin into an equally cared for holder, like that clean ball bearing drill chuck closes on a bit.

Draw bar is not alone, the thrust washer, the seat it rides, even the hole have to be attended periodically. The unappreciated key becomes the weak link, as when dirt imposes a false sense of tightness, resulting in it shearing or at least burring, making each next change a little more difficult.
Other misuse occur by holding wrong diameters "it's just a little off" that springs or deforms the collet. All collets have a min/ max tolerance to diameter; only exact diameter initiates cylindrical clamping generated by the taper.
Only the collets split alternately from each end [such as DA, ER, TG, WW, C series.....] have appreciable deflection to accommodate variance from stated size; not 5C, R8, 215, 2J........... .
Also why those latter collets are proportionally longer, comparing cylinder section to spring section, recovering some grip size flexibility. Never as well as the former, which essentially are cylindrical all the way through. We knew those as 'accommodation' holders, easily identified by distinct dual opposing tapers, though most are two different tapers, simplifying orientation in respective holders. A few can insert correctly either way.

Of the smaller machines, R8 is hugely successful; because the spindle's easily made, just like the collets, making everything more economical, been around f-o-r-e-v-e-r. My horizontal 2B Milwaukee, ~1910, 40 taper has an aftermarket, adjustable R8 swivel milling head from slightly later period. That draw bar not even 4-5 inches long. I'm certain the key is original. I've only seen one other, both clamp the overarm. Sorry, unmarked in brand or patent.

Finally, the real limitation of R8 [our8?] is not support in a spindle of 1.875 in. (48 mm) or quill of 3.375 in. (86 mm); it's tool length per diameter. Large collets have reduced cylindrical sections. Look inside 1/4" 3/8" or 1/2" and then 3/4" or the worst of all 7/8". I'd no more expect to take any kind of material with 7/8" than a minimal squaring up square tube for weldment. Wonder why 3/4" standard double-end endmills are too long for R8? When that's needed, use an endmill holder, setscrew engages the Weldon flat. And you can pull and replace to nearly identical Z height.

[side note; a shop owner and his cohorts I despise, pronounce it weld-e-mint]. Byword in same place is 'we always did it this way'.
So astute! Not!
Me Judgemental? You bet, I had incredible, astounding, respected mentors.
 
brino said:
Is it just me,
or does the collet stick-out look very different between with draw-bar (from post 38):
View attachment 350261

and no draw-bar (from post 50):
View attachment 350264

Was that the same R8 collet?
Of course, one also has a tool in it and the other does not.
Is that the proper collet for the tool? (say both 3/8")

I'm suspicious of it being a Morse taper spindle.
Do you have any MT-2 or MT-3 arbors to try?

-brino
Click to expand...

I have centers in mt2 (too small) and mt4 (too large). I could buy a cheap mt3 shank to check.
 
Just for kicks, try the MT4 in the spindle.
I am going to try a MT3 in my spindle.
 
That big set screw near the top of the spindle might just be a bearing oiling port. I know my millrite has something exactly like that.
 
r-mm said:
I have centers in mt2 (too small) and mt4 (too large). I could buy a cheap mt3 shank to check.
Click to expand...
the measurements on your chuck arbor seem to be close to MT4.
Does it have a groove in it ?
An MT3 does not come close in an R8 spindle.
 
Last edited:
Discounting possibility of wrong taper, the 1st photo compared to 2nd is missing the thrust washer critical to R8. Tapers of Morse and Brown & Sharpe spindles qualify for milling, all there was in the old days. Most retained by drawbar, located by taper, driving friction aided by taper, compared to tang in a drill press. Not universally though.
Easy way to tell. Flashlight and mirror. Take out drawbar, shine flashlight at side from below, see view in mirror.
Or stick finger in. If you feel a taper end about 3/4 inch in, R8 TYPE collet, because of drawbar. TYPE in caps, due to some proprietary spindles. Continuous taper longer than finger is 'Long taper' of Morse, B&S, Jarno or a couple others. No big deal, first [way more common] two are not rare. Never saw Jarno on a mill.....just lathes and grinders.
Should taper be the case, we'll devise method determining it with you, remote control. Until then, Machinist's Handbook or

Avoid links to LinkedIn like a plague. Not just COVID variety. lol. Enough spam and info-piracy going on to make Facebook and most career sites jealous. Posers, armchair experts, witless toads, ad infinitum. Cornucopia if you prefer.
 
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