The Shop > Tools
Any advice on pressurizing (grinding) spindle?
philf:
Hi Pekka,
I think the max speed is about 8,000 rpm using a 3,000 rpm motor. I'll put a tacho on it to see. I have a 2-step pulley and think one ratio gives me 1:1. [Edit: I was close - 3,500 rpm and 9,000 rpm.]
The attachment in use cutting a ballscrew:
The spindle takes 8mm watchmaking collets and arbors. I have a Quorn T&C grinder which uses the same arbors so can use the wheels made for that.
The attachment fits in place of the quick change toolpost. The bore for the bearings was machined in-situ so the spindle is at the lathe centre height.
I reground my D1-3 spindle nose with it and have reground the jaws on several chucks.
The motor came off a small pump and I thought it may be too small but if I take things easy it's OK.
Phil.
PekkaNF:
That is a very nice ginding spindle. Quorn-type bearing arragement?
Thank you for showing that, it is very inspirational.
Pekka
philf:
--- Quote from: PekkaNF on June 16, 2017, 05:16:44 PM ---
Quorn-type bearing arragement?
--- End quote ---
No - just two identical 15 x 24 x 5 bearings with a spacer loctited in the bore between the two (made it easy to make with just one hole bored straight through). The bearings are slightly preloaded with two locknuts on the spindle. I did intend getting a preload washer but they're not easy to buy as a one-off. It seems to work fine as it is.
Phil.
PekkaNF:
Thank you Phil.
I tried to disaaseble the spindle, I see the bearing sizes, but dissambly is ont super easy. Everything is glued, even moderate heating does to work, have to heat it near 100C.
For set screw I had to modify allen key, 2,5 was way too loose, 3 mm or 7/64" would not go, I used diamond file to reduce 3 mm to 2,7 mm AF, hammered the key in, heated the spindle end to 65-100C and used pliers to crack open the set screw. You don't want to brak the set screw it is on alminium part and abuts agains spindle nose thread. Glued. Lovely.
After set screw is off the way, that aluminium shaft nut comes out easy with 17 mm AF spanner.
Spindle presses out from bearing housin easy.
There is a bearing nut inside the bell housing and that is glued and tight. Not off yet.
PekkaNF:
it needeed a got tightening on lathe tool holder from 43 mm circumfrence, application of heat gun on the castellated nut and a good grunt with a "special" tool + spanner. Bearings were finger tight on housing.
It had a liberal amount of green thread locker. Any recommendation? I don't want to go this tight again. Locktite 222?
Here are the pictures. It had some debris between bearings! And I could hear rought sound when I rotated them, nothing really agricultural wear, but clearly pasti it's prime.
Going to order some RS or RSL sealed bearings.
Pekka
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