[Al_The_Man]

That is pretty high lead screws, nice but the inertia will be quite large, and the higher the lead you are losing reduction value of course.
BTW, those retro-reflective sensors only have 1mm sensing distance with optimum reflective material.
Al.

[hub]

That is pretty high lead screws, nice but the inertia will be quite large, and the higher the lead you are losing reduction value of course.
BTW, those retro-reflective sensors only have 1mm sensing distance with optimum reflective material.
Al.

Thanks
Yes, I did notice.. With my 400W servo (servoS in the future) the inertia calculations require reduction, but a low one 1:3 should work according to the servo tuning manual. That still would produce insane speeds, the servo rotates 3000 rpm, and @ with reduction (1000rpm) it's still way more speed than I would ever need. And low/moderate acceleration I would think.

Do you think it would be worth trying or just forget about the big (heavy; high dia; high lead) screws?
As it is, my machine is mainly made of aluminium extrusions. I will reinforce with steel later as needed.

About the sensors,
Yes the sensing distance is small, but pretty decent accuracy I think. I just need to make the mechanics according. Still on the drawing board..

Hub

[RomanLini]

Just a thought, retro-reflective sensors are not great for limit or homing switches, the "edge" they detect will shift depending on ambient light and of course even a tiny woodship or dust etc in there can affect the sensing point (or even disable the sensor).

You might want to check out the thread on;
http://www.cnczone.com/forums/open_s...made_easy.html

As they are a very good choice of switch for home and limit sensors, and are basically impervious to chips and dust and room lighting.

[hub]

Just a thought, retro-reflective sensors are not great for limit or homing switches, the "edge" they detect will shift depending on ambient light and of course even a tiny woodship or dust etc in there can affect the sensing point (or even disable the sensor).

You might want to check out the thread on;
http://www.cnczone.com/forums/open_s...made_easy.html

As they are a very good choice of switch for home and limit sensors, and are basically impervious to chips and dust and room lighting.

Thanks Roman, yes I agree. I bought them along with other stuff because the didn't cost much. Just to fool around with them & see if they might be useful for something. I had lots of doubt they would work (and still do) not to mention they would be very hard to solder... TINY. I'm not sure if they are even worth a try..
My original idea was to use micro switches to trigger rough limit position and a fork sensor to dial in the precise position from a disc attached to the leadscrew. (Like an encoder kind of).
But, LOL, the micro switches I ordered were actuators only..!

Anyway, I'm used to 24V industrial sensors, that's what I'm going to use in the end I think. I've had SO many problems with 5V triggering it's not funny anymore. Had to install scmidth triggers to filter etc etc...

Hub

[hub]

Since I had problems with timing pulleys connecting 2 lead screws, I got a couple of big steel ones to eliminate slipping etc. Bored the pulleys with a drill press.
But, when starting to CNC.. it resulted in 2 scrap parts.... First went very bad, after a while I located the problem(s), two motor wires had come off from the stepper drivers (X & Y). (Note to myself: connect everything properly, even if it's temporary).
The second part was scrap too, the Y stepper stalled. I lowered feed and after that the third go at it came out almost perfect. SLOW but result were good.

[hub]

Made one of the ball screw bearing blocks. Wow turned out very nice. BUT... wrong bearing fit I had by mistake designed the dimensions for a different bearing..
Made corrections & new gcode & machined again. Turned out good this time.

[CarveOne]

Made one of the ball screw bearing blocks. Wow turned out very nice. BUT... wrong bearing fit I had by mistake designed the dimensions for a different bearing..
Made corrections & new gcode & machined again. Turned out good this time.

CNC machines are very smart. They let us know about every mistake we cause them to make. Even when we have them make the same mistake multiple times on the same material.

CarveOne

[hub]

True But my machine is less smart at the moment. It has no limit switches, so if i tell it to move it will without a doubt, even if it destroys itself in the process

[CarveOne]

True But my machine is less smart at the moment. It has no limit switches, so if i tell it to move it will without a doubt, even if it destroys itself in the process

My machines have no limit switches, mechanical or software. I like simplicity. It forces me to think about what I'm doing. I'm not infallible though.

CarveOne

[RomanLini]

My machines have no limit switches, mechanical or software. I like simplicity. It forces me to think about what I'm doing. I'm not infallible though.
CarveOne

Do you have homing switches though? I don't think I could live without mine. If there's a problem and I pull the plug halfway through a job, it can re-home later and start cutting at exactly the same position on the job. There's even been some jobs I've cut part of it one night then went to bed and the next day re-homed and finished the rest of the job.

But as far as limit switches go I never bothered fitting any, and have not missed them.

[CarveOne]

Do you have homing switches though? I don't think I could live without mine. If there's a problem and I pull the plug halfway through a job, it can re-home later and start cutting at exactly the same position on the job. There's even been some jobs I've cut part of it one night then went to bed and the next day re-homed and finished the rest of the job.

But as far as limit switches go I never bothered fitting any, and have not missed them.

No home switches either, but when I get back to working on the smaller steel machine I'll add Gerry's latest version of the 2010 screen set and add the three home switches and the zero plates. I have been taking a later than normal break from the CNC stuff this year to do much wanted property improvements. I should be able to start the upgrades in a couple of weeks now that the outside work has just about wound down.

CarveOne

[cornbinder23]

No home switches either, but when I get back to working on the smaller steel machine I'll add Gerry's latest version of the 2010 screen set and add the three home switches and the zero plates. I have been taking a later than normal break from the CNC stuff this year to do much wanted property improvements. I should be able to start the upgrades in a couple of weeks now that the outside work has just about wound down.

CarveOne

Dont you mean 4 home switches?:stickpoke

JTCUSTOMS

[hub]

Limit switches is like insurance. You don't need it/them until something very unexpected happens. So far, I have managed well without, as I have been very careful. And been running new g-code with my hand ready to push estop..
I will install some limit switches because: "just in case something goes wrong". They probably are useless hopefully, but just in case..

Automatic homing is another thing though. That would be very useful (or fast that is, not to have to edge detect etc etc to home when needed)

[Khalid]

Limit switches is like insurance. You don't need it/them until something very unexpected happens.

We i.e. Roman, Gerry ,CarveOne and me off-course not using Limit switches. Some of us however using soft-limits in Mach3. I never use Home switches and limit switches in my nine years carrier of CNC but now i need to install Home switches( This is the fact that i want to get real advantage of home switches as Roman mentioned) on my new router and to use Gerry 2010 screensets for auto tool zeroing and probing.

[CarveOne]

Dont you mean 4 home switches?:stickpoke

JTCUSTOMS

EEERRR, yeah, I stand corrected. Four it will be. For auto squaring function, plus A axis damage control.

CarveOne

[hub]

Soft limits is fine as long as the controller knows for sure the position. Would be fine I think in a closed loop servo system.
But, my machine has 2 steppers & only one servo at the moment. I just can't trust soft limits.. because at times steppers can stall (at least mine do), Mach3 happily moves on without knowing one axis is not moving. Soft limits & home position -> useless..

It works (kind of) if you are standing next to the machine all the time & press stop if a stall happens.
But I want the machine to know if it has made a "mistake"

We i.e. Roman, Gerry ,CarveOne and me off-course not using Limit switches. Some of us however using soft-limits in Mach3. I never use Home switches and limit switches in my nine years carrier of CNC but now i need to install Home switches( This is the fact that i want to get real advantage of home switches as Roman mentioned) on my new router and to use Gerry 2010 screensets for auto tool zeroing and probing.

[hub]

Time just flies...
Did the last part (bearing block) for the gantry ballscrew assy. A few minor problems, but it turned out well in the end. Hope to replace the old threaded rod with the new one tomorrow. (Or soon anyway).

[hub]

Machined bearing block. Made of thick chipboard for now...

[hub]

Installed the ballscrew assy And the servo is still not installed, but will be soon I hope..

[hub]

Got my "new" (used) servo & attached cyclo-gearbox today. It's big compared to my 400W AC servo..

However, I can't find much info on it. The best I found was: ABB - Servo Motor - 4412400131 - AC Servo Motors

The + & - is clear (), but what are those encoder wires? Which is which?

Type: Permanent magnet DC servo
Brand: ABB
Model: 4412400131
4000RPM
24A, 84V (wow...) that's 2kW.. Any suggestion on what driver I could use to drive it?..