Re: [Emc-users] Something to think about re the hack-a-day tool changer

2019-04-17 Thread Ken Strauss
The cheap load cells often use a HX711 for the amplifier and A/D. See https://www.instructables.com/id/How-to-Interface-HX711-Balance-Module-With- Load-Ce/ if you're using an Arduino. If you want to roll your own interface code see https://www.mouser.com/ds/2/813/hx711_english-1022875.pdf >

Re: [Emc-users] Something to think about re the hack-a-day tool changer

2019-04-17 Thread Chris Albertson
I thought the nut that needed to be torqued down was on the spindle. You would not be using a stepper for the spindle motor. So the "wrench" holds the nut and then you power up the spindle to tighten the nut. If that is the case then spindle motor current tells you the torque on the nut. But

Re: [Emc-users] Something to think about re the hack-a-day tool changer

2019-04-17 Thread Gene Heskett
On Wednesday 17 April 2019 15:06:02 Chris Albertson wrote: [...] > > But if maybe you lock the spindle and turn the nut. This is the case, except you are turnbing the nut by using the xy steppers to drive the carousel which is turning the nut. > Then your spindle > lock needs to have a torque

Re: [Emc-users] Something to think about re the hack-a-day tool changer

2019-04-17 Thread Gene Heskett
On Wednesday 17 April 2019 15:32:09 Ken Strauss wrote: > The cheap load cells often use a HX711 for the amplifier and A/D. > See > https://www.instructables.com/id/How-to-Interface-HX711-Balance-Module >-With- Load-Ce/ if you're using an Arduino. If you want to roll your > own interface code see

Re: [Emc-users] Something to think about re the hack-a-day tool changer

2019-04-17 Thread Gene Heskett
On Wednesday 17 April 2019 01:48:06 Chris Albertson wrote: > I think you could eliminate the load cell and simply measure motor > current. Given that the motor is locked at zero RPM, the torque would > be a function of current. Once you calibrate current to torque it > will not change. You

Re: [Emc-users] Something to think about re the hack-a-day tool changer

2019-04-17 Thread andy pugh
On Wed, 17 Apr 2019 at 06:57, Gene Heskett wrote: > Some more along the lines of finding out how much force I can figure on > as being available to tighten or loosen the collet nut. I can get, for > under a tenner, 4 ea 50Kg load cells and a processor board that converts > the very low level

Re: [Emc-users] Something to think about re the hack-a-day tool changer

2019-04-17 Thread Gene Heskett
On Wednesday 17 April 2019 07:12:53 andy pugh wrote: > On Wed, 17 Apr 2019 at 06:57, Gene Heskett wrote: > > Some more along the lines of finding out how much force I can figure > > on as being available to tighten or loosen the collet nut. I can > > get, for under a tenner, 4 ea 50Kg load