[badhabit]

45Kn on such a small machine is quite high to release the tool, but I guess you have a double spring drawbar to release ? Did you try a hand pump to find actual pressure needed ? You could try an air/ oil intensifier if stroke isn't too long.

Yeah, i talked to the manufacturer and minimum is 40kN and recommended 45kN. I also find it extremly high, i was a bit surprised that it was so high. I don't know if there is double springs or not....

I solved it with a block cylinder:
https://shop.amf.de/application/amf_...SEITE:Liste)=Z
...together with a pneumatic pump:
https://shop.amf.de/application/amf_...SEITE:Liste)=Z

....with the correct pneumatic valves and pressure sensors and a bit of control, I believe i'll get both a fairly fast release and the pressure i need to release the tool...I'll know later if this works :-)

[badhabit]

Hi Badhabit- If the cable fatigues use synthetic cable. Dynex, dyneema, hampidjan have suitable cable. Cheers Peter

https://hampidjan.com/

Yeah, i searched for synthetic cable(looked at kevler "wire" amongst others), but actually wasn't able to find any that would work....but yeah, might need to investigate a bit more if the steel wire starts acting up...

[badhabit]

the hose bending problem, there are these 45, 90 degree bent steel connector hoses with high pressure rating from SKF, these plug directly into a quick connector. come in different diamater and mount on a high pressure black hose. skf recommends using the ones with a notch at the end of the steel tube

https://schmieranlagen.shop/armature...r/rohrstutzen/
https://schmieranlagen.shop/armature...druckschlauch/

The issue is not as much the connectors, but more the "dynamic" bending of the those/tube inside the cable-chains when the saddle or the table is moving... this radius is very small in my setup and this will cause premature fatigue or kinks in most tubes...so the challenge is to find a tube/hose which allows for very tight bending during movements....

[servtech]

Yeah, i talked to the manufacturer and minimum is 40kN and recommended 45kN. I also find it extremly high, i was a bit surprised that it was so high. I don't know if there is double springs or not....

I solved it with a block cylinder:
https://shop.amf.de/application/amf_...SEITE:Liste)=Z
...together with a pneumatic pump:
https://shop.amf.de/application/amf_...SEITE:Liste)=Z

....with the correct pneumatic valves and pressure sensors and a bit of control, I believe i'll get both a fairly fast release and the pressure i need to release the tool...I'll know later if this works :-)

Seriously high rated pressure at 500bar when most industrial CNC machines run at 60 to 80 bar. Presumably the pressure you will use is much reduced and reduced to compress the drawbar spring?

[badhabit]

Seriously high rated pressure at 500bar when most industrial CNC machines run at 60 to 80 bar. Presumably the pressure you will use is much reduced and reduced to compress the drawbar spring?

Yeah, i'm not gonna need 500bar, around 350bar should do it with the cylinder i've chosen.... but even 350bar scares me a bit...and forces at 45kN is also scary... its going to be a scary machine :-)

[badhabit]

It seems like the AMF shop does not like me linking to their items...so the links above dont work :-(

Anyways, their catalogue is here:
https://www.amf.de/files/amf-assets/...ng-Systems.pdf

I've ordered their air-hydraulic pump order no "69450" together with a 24V valve(no. "259242") and a clock cylinder with orderno "63461" ....

[servtech]

Yeah, i'm not gonna need 500bar, around 350bar should do it with the cylinder i've chosen.... but even 350bar scares me a bit...and forces at 45kN is also scary... its going to be a scary machine :-)

Special pipes needed if used. In old money 350bar is around 5,000 psi !

[badhabit]

Special pipes needed if used. In old money 350bar is around 5,000 psi !

...soooo, my old gardenhose aint going to cut it? ;-)

I talked to a local hydraulics supplier and they had no problems supplying the correct hosing for the connection, they just needed to know the final length i wanted. So my plan is to get everything mounted, measure the required hose-length and then have them make the proper hose for the connection...

[ardenum2]

Do your hiwin rails have channels running on the underside or are they fully flat?

[badhabit]

Do your hiwin rails have channels running on the underside or are they fully flat?

The rails have two groves on the underside, but otherwise flat:
Attachment 488604

We had a lot of problems getting things as "flat" as we wanted when the rails were mounted. The rails "twisted" in all sorts of directions after mounting, not much, but it wasn't "perfect". So we ended up machining a grove for the middel part so the rail "only" rests on the two outer flats:
Attachment 488606
...after this the "flatness problems"(twisting) went away....my/our theory is that i've designed the mounting surfaces wrong and should have "counterbored" the mounting holes... the teory is that when i torque down the bolts in the rail i actual "lift" the metal around the thread in the mounting surface and this causes the rail not to sit flat against the surface(the surface around the threads are "bulging" up and preventing the rail to touch on the outer edges)... With the slot machines around the thread there is room for this "bulge" and it can now sit flat and the weird "twisting" disappeared....if i were to design it again i could have "counterbored" the threaded holes in the mounting surface a couple of milimeters to avoid this in the first place...

i don't know if this makes sence or answers your question :-)

[ardenum2]

Thanks, it does, seems like a design flaw on hiwins part. On their newer ones CG they went away with the middle part



Have to think more about it or just go one size smaller size20 rollers have no grooves, fully flat.

[badhabit]

Thanks, it does, seems like a design flaw on hiwins part. On their newer ones CG they went away with the middle part
Have to think more about it or just go one size smaller size20 rollers have no grooves, fully flat.

It would be easy just to counterbore all mounting holes a couple of milimeters and the problem is not an issue...It isn't too much work and it is an easy way to completely avoid this (potential) issue...

/Thomas

[ardenum2]

are you happy with CTB's servo drives? Have you had a chance to test them out yet?

[badhabit]

are you happy with CTB's servo drives? Have you had a chance to test them out yet?

Yeah i've been testing them, but not really been putting them through their paces just yet. Everything seems to work fine through EtherCAT. The only thing i cannot get to work(yet) is the motorload feedback from the driver to LinuxCNC. I'd like to show the load of each axis and the spindle, but it seems to only return 0 whatever i do. I've talked to a couple of engineers at CTB about this and it should work, so it might just be because i've misconfigured something in either the driver or in LinuxCNC...it woudn't be the first time this happened ;-)

I'm currently wiring all the motors and sensors and plumming the spindlecooling...i'm currently struggling with "humongous" leadtimes on the Beckhoff EtherCAT modules i need for all the sensors, valves and stuff, ETA is in August(6months from now!):-/ But when all this is done i'll hopefully be ready for the first real movements of the machine...then i'll be able to give more information on the CTB-stuff...

[ardenum2]

The issue is not as much the connectors, but more the "dynamic" bending of the those/tube inside the cable-chains when the saddle or the table is moving... this radius is very small in my setup and this will cause premature fatigue or kinks in most tubes...so the challenge is to find a tube/hose which allows for very tight bending during movements....

you could move the bend outside the carriage and use an energy chain with a bigger minimum radius, you're using telescopic steel covers not bellows so you should be able to fit it right under, how big is the current bend in mm?

[badhabit]

you could move the bend outside the carriage and use an energy chain with a bigger minimum radius, you're using telescopic steel covers not bellows so you should be able to fit it right under, how big is the current bend in mm?

Yeah, well, that is the exact issue. There isn't room really inside or outside for anything with a bigger bendradius, i've maxed it out and i've still only got something like r=30mm which isn't great... but i think the brake-line solution will work just fine...

[ardenum2]

Yeah, well, that is the exact issue. There isn't room really inside or outside for anything with a bigger bendradius, i've maxed it out and i've still only got something like r=30mm which isn't great... but i think the brake-line solution will work just fine...

oh ****, that's exactly how much I have, the hoses I linked to earlier I mistook r for d, the smallest they have has a r=35mm so I'm gonna have the same issue now, damn, I always use d in cad so I naturally think in d's...

[badhabit]

oh ****, that's exactly how much I have, the hoses I linked to earlier I mistook r for d, the smallest they have has a r=35mm so I'm gonna have the same issue now, damn, I always use d in cad so I naturally think in d's...

Yeah, that is too small... you are also going to have problems with finding cables that can handle that small of a radius... so change it if you can...r>60 and things start to lighten up...

[ardenum2]

you have 35 size rails right? what's the diameter of the pin that you use to push the rail against the edge? where did you get them?

[badhabit]

you have 35 size rails right? what's the diameter of the pin that you use to push the rail against the edge? where did you get them?

I've used 4mm dowel pins. I tried 3mm but i thought they were a bit too small for my liking. I actually made a small test-jig where i mounted one of the countersink screws to figure our the correct size and the correct distance. I just found my original drawing with the 3mm pin:Attachment 488786

I kept the 41mm distance, but changed to 4mm during assembly...but make sure to test it for yourself and not just use my drawing, the head of your countersink bolts might be different!

You can buy these pins in almost all "professional" hardware stores. I bought mine at a local "bolt supplier"(mw.dk), but you can buy them online aswell, like this one: https://uk.misumi-ec.com/vona2/detail/221000596803/