Tool Post Grinder

whydontu

whydontu

I Tried, It Broke
Premium Member
PeterT said:
Is that the same motor? The Amazon link shows an output shaft (presumably running through bearings) & separate ER 'collar' mounted on shaft retained by set screw.
But your disassemble pic looks like an integral ER shaft running through motor housing/bearing(s)

View attachment 42383View attachment 42387
Click to expand...
I should have been more careful in my selection of Amazon offerings. The motor and controller I bought has a solid shaft with the ER11 collet socket machined directly into the shaft.
Some if the specs are BS, maximum RPM is 12,000, and actual current draw is more like 100 watt at 48 volt. But it is very smooth and quiet and is a massive improvement over the original brushed 24v spindle I had.

 
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PeterT

Ultra Member
Premium Member
Yup, that's why I was asking. The integrated ER shaft brushless model you show seems to be a step up in a few respects & seems to get better reviews with a few mini CNC posts I've read (but I have no firsthand experience with). Probably why it costs more too. Yes the power specs are bogus & I've very suspicious of stated runout too. I'm contemplating the same one, so keep us posted how it runs. Heat is the enemy on these & despite seeing some teardowns, I can't see if they have any temperature compensation meaning floating (typically rear) bearing assembly. Maybe mini CNC guys just know how not to push them, but grinding can be a power consumer even with innocent looking material removal rate, so something to be aware of.
 
whydontu

whydontu

I Tried, It Broke
Premium Member
PeterT said:
Yup, that's why I was asking. The integrated ER shaft brushless model you show seems to be a step up in a few respects & seems to get better reviews with a few mini CNC posts I've read (but I have no firsthand experience with). Probably why it costs more too. Yes the power specs are bogus & I've very suspicious of stated runout too. I'm contemplating the same one, so keep us posted how it runs. Heat is the enemy on these & despite seeing some teardowns, I can't see if they have any temperature compensation meaning floating (typically rear) bearing assembly. Maybe mini CNC guys just know how not to push them, but grinding can be a power consumer even with innocent looking material removal rate, so something to be aware of.
Click to expand...
My no-load runout is perfectly acceptable. Video at https://canadianhobbymetalworkers.com/threads/new-cnc-engraver-spindle.9344/#post-137483

I didn’t pull the rear bearing, but the front bearing is live loaded with a wave washer.

Might be a bit before I try the motor as a tool post grinder, project #42c.
 
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