[kreutz]

John;
If I ever find the Altium schematics and pcb files for the HP UHU project I will contact you in order to send them via email. Also the compiled libraries for the project (if I'm lucky enough). Don't count on them yet...

[cnc2]

Here you can find the partslist for the UHU http://gsst.wikispaces.com/UHUget
Questions or improvements can be discussed in this thread.

Hi everybody !

I just got the parts from Reichelt.de and just found that the copper boards have 35 micro meter of copper on them not the 75µm claimed in the parts list, and after verification Reichelt.de sels only 35µm copper boards what ever the kind.

Thanks !

cnc2.

[rasta]

Hi; could someone please point me to a place were I can download the instructions to build these boards and the parts list?
Thank you
Mariano

- - - Updated - - -

Hi; could someone please point me to a place were I can download the instructions to build these boards and the parts list?
Thank you
Mariano

[jcdammeyer]

Hi; could someone please point me to a place were I can download the instructions to build these boards and the parts list?
Thank you
Mariano

- - - Updated - - -

Hi; could someone please point me to a place were I can download the instructions to build these boards and the parts list?
Thank you
Mariano

I don't think the boards for the HP_UHU are available anymore. Kreutz was the designer. Likely he may have a web link to gerbers etc. for making more boards. I can email things like parts lists etc.

- - - Updated - - -

Hi; could someone please point me to a place were I can download the instructions to build these boards and the parts list?
Thank you
Mariano

- - - Updated - - -

Hi; could someone please point me to a place were I can download the instructions to build these boards and the parts list?
Thank you
Mariano

I don't think the boards for the HP_UHU are available anymore. Kreutz was the designer. Likely he may have a web link to gerbers etc. for making more boards. I can email things like parts lists etc.

[kreutz]

Hi,

I sent a PM to Rasta, I will look into my old backups for the information required to make the board and email it to him. I don't have a website to post it anymore. If there is more interest I can upload it to Mega.

Regards,

kreutz

[jcdammeyer]

Up until mid June my Windows Home Server was reliably backing up WIN-XP, WIN-7, VISTA and WIN-10. Now it still does those but something in one of the microsoft databases for WIN-7 has been corrupted and I've not been able to fix that. And there's been too much new development not saved in that system.

It's a pity that WHS was dropped. If the hard drive on the your system failed it was a simple matter to install a new one, insert a CD and boot from it. Tell it to find the WHS and then select which system you want to restore. After X hours you'd be at the last back up point including all secret license codes unique to that machine. Something much harder to do with simple file backups.

At this point I don't know what to do with the WIN-7 system. Once option is to get a new hard drive, restore it from the point before it became cranky. Then pull in copies of any of the important data files. Of which there are a number of Protel-99SE and Altium.

[jcdammeyer]

Quick question about the current limit settings. Looking at the schematic of 1.0c or d there's a VREF and a VREF_OC. VREF is a lower voltage than VREF_OC but it's the input into the slow_limit RC network.

So how exactly does this work. If the motor is normally a 2.8A motor with a rated torque of 1.27 N.M. but a peak torque rating of 3.9 N.M. so I'd guess a peak amp rating is scaled the same to 8.6A.

The question then is what to set the reference pot to. The combined sense resistors with 0.01 Ohm will have 28mV across them (I * R) for 2.8A and 86mV for that peak current.

So what value is VREF at the "TP Current Limit" set to?

[kreutz]

I think you better increase the value of the sense resistors in order to improve the S/N ratio at the comparator, let's say you replace the two parallel current sense resistors by 0.2 ohm 5 Watts non-inductive resistors. Then the current limit Vref should be adjusted to 0.280 Volts and the OC_Vref to about 0.80 Volts in order to make use of the intermittent maximum torque capability of your motor. The resistors will get hot when in the intermittent torque zone but will lower the temperature during normal torque usage, make sure you separate the resistor body from the pcb surface to allow for airflow and avoid toasting the pcb.

[jcdammeyer]

Thanks. I used the numbers I had off the top of my head for my Bergerda AC Servos. Actually the original motors I was using were:
Skewed Rotor Design:
Constant Torque: 1.6 N-m ( 226 oz-in)
Peak Torque: 8.0 N-m ( 1125 oz-in)
Max Speed at Voltage Constant: 3200 RPM
Terminal Voltage: 90V
Constant Current: 7.8A
Peak Current: 40A
torque Constant (KT): 0.182 NM/am
Voltage Constant (KE) 18.95 V/rpm
Resistance: 0.925 ohm
Inductance: 2.5 mh
Inertia: 3.4 kg/cm^2

But at the moment I want to play with a 24V motor that is marked with these spec's.
I sub n = 2.7A
I sub fm = 24A.

So say I change the two current sense resistors to 0.4 ohms to get a parallel value of 0.2 Ohms x 2.7A = 0.54V.
Attachment 483724

The Rev 1.0d drawing has two trim pots as shown above. My boards have only one. I should probably modify the boards for two or set up a different divider for the VREF while the VREF_OC is adjusted with the pot.

I think the references are not named to guide their purpose. The fast limit is designed to shut down drive when current exceeds VREF_OC which is the higher current setting. VREF_LOCKED_ROTOR is perhaps a better name?

The VREF signal controls the slow limit which requires the current to be there for some time before it trips and shuts down drive to the motor or restarts it. Perhaps VREF_MOTOR_MAX.

With those names it's obvious we'd want VREF_MOTOR_MAX to trip on 2.7A and VREF_LOCKED_ROTOR to be 24A or some value between 2.7A and 24A to prevent burning up the motor.

Have I got that right?

[kreutz]

In the HP_UHU Vref (slow limit) is the trigger point to integrate the current vs time the motor stays above Vref, VRef is equal to the Continuous Current limit of the motor times Rs (Ic*Rs). The motor is allowed to go over this continuous limit for some time, that is, to operate in the intermittent zone, factory limited (generally) by the temperature rise in the motor.
Vref_OC sets the Maximum Current limit for your motor (Fast Limit) because it will damage your motor to exceed this current.

If you replace the resistors by 0.4 ohm ones, they must be rated 10 Watts each, or they won't last. It all depended on how much time your equipment stays over the continuous torque limit of the motor and how frequently it does it. If you notice they get too hot, use some speed reduction mechanism after the motor in order to multiply the torque so to avoid overloading it.

[jcdammeyer]

Thanks Hugo,
I have a project in mind for one of my UHU or HP_UHU boards. Hence some of the questions.
I use both R8 and an R8-TT collet on my mill. So most of the tools are in TT holders that slip into the 0.75" flatted face R8 collet.
To drop a tool requires maybe 1 to at most 2 turns of the drawbar.
To remove the R8 TT collet and say insert my R8 Face Mill requires about 12 turns of the drawbar which I don't want to do each time I remove a TT holder.

Specified torque for R8 tooling is about 20 ft-lbs although it's unlikely I have ever tightened them that much by hand. But I did build a butterfly impact wrench system along with a socket revolution counter to try and automate things.
Attachment 483730
It sort of works but not well. There are two issues.
1. The socket doesn't always end up lined up with the head and can even jam on crooked so I added a sensor for all the way down.
2. If the drawbar is not very tight and a short blip of the air to the butterfly wrench sends it spinning and once loose can literally over spin and drop the R8 collet.

Essentially the problem with the butterfly impact wrench is unloaded is way too fast to be able to properly control.

I'm using a controller I scavenged from a different project.
Attachment 483732

Clearly the butterfly wrench isn't suitable for automated behavior. So I want to drive the drawbar socket with a motor and reduction that at highest power will create 25 ft-lb torque. But I never want to tighten it with more than say 18 ft-lb of torque.

What I thought I'd try is turn a DC servo for 12 turns or until motion stops and say a 2.0A current limit is reached or a timeout. That's to tighten.

To loosen if it's a TT Holder the button to release is just tapped and the motor torque is increased to 2.7A and turned for 2 revolutions. (actually way more depending on reduction gear).

To loosen and remove the R8 collet or tool, the button is held for more than 1/2 second and again torque is increased to 2.7A but now 16 revolutions or as long as the button is held or a timeout.

So I thought I'd use a UHU and make it possible to adjust the reference so it always has reserve torque to loosen but can never tighten more than a preset value. Once the motor stops the continued steps into the UHU will create a following error. That's the indication that the drawbar is tight. A signal from the controller will toggle the reset line on the UHU to undo the fault.

So either a relay that switches in a parallel resistor into the reference setting or even a PWM generated filtered voltage to serve as the reference.

So that's the background. Where I'm undecided is which Vref to 'tweak'.

[jcdammeyer]

I've been here before so to speak. What you see in this photo is a servo motor controller by CAN messages into a 100:1 reduction drive which goes into another reduction drive. The square aluminum bar represents a mast that is raised and lowered. The module at the end of the mast is an inclinometer, also reporting via CAN messages.
Attachment 483972
The motor is controlled via Torque and Velocity mode. As it approaches an angular set point it switches over to torque mode to nest smoothly against an end stop. It also moves off the stop with torque mode in case the locks are in place. Then at full speed until the next angular set point and then back to torque mode.
I 3D printed the motor and reduction drive holder.
Attachment 483974
I've attached the pdf of the motor. It's 5000 RPM, up to 5 NM and 1.6kW all at 24V. Way too big for what I need but then what it actually lifts is way heavier and it does it very quickly. Would have been nice to score the test system for myself but I no longer work for that company and they are still using it for firmware changes.

[kreutz]

There is a thread, somebody tried to make it work with steppers: https://www.cnczone.com/forums/mecha...-software.html
No conclusion but it might give us ideas....

You should keep on pursuing the DC servo/gearbox approach, the air-cylinder driven solution doesn't go well with using different types of tool holders, which will require complete disengagement from the drawbar. The torque limits (Vref) could be made to change via relays/mosfet-switches driven by the tool-change macro. But it still will require a way to align the drawbar square with the driven socket, some kind of drawbar position sensor or magnetic forced alignment, there is also the drawbar brake which must be handled by the macro too. It will be good to include a selectable impact phase to tighten the nut and release it without over-stressing the motor by stalling it.

That Brushless CAN motor seems interesting too.

[jcdammeyer]

That's exactly what I had in mind! He uses two air cylinders and has the spindle brake so he can turn the nut until it engages. That's been one of my problems with nut rounding happening when the impact wrench doesn't set the socket properly and then spins.

Or, now that the nut is a bit damaged, jams when down and then pulls out of the 3/8" drive and stays stuck to the draw bar nut. Eventually I'll have to replace the draw bar nut.

I don't have an encoder on it. Just one PPR pulse with hall sensor. I do have a sensor for socket all the way down.

I've also whipped up a drawing and G-Code for a spindle lock but haven't actually made it yet.
Here's a JPG of the assembly. The shape of the lock has changed a bit but you get the idea. Having a spindle lock will make even just manual operation easier.
Attachment 483982

And I had thought about using a DIP relay to switch in a different current limit resistor just as he did. But if I have a processor available that can do PWM or D/A then I have much better control over torque.

I've been in contact with H.O. with respect to his MicroChip PIC version of the HP_UHU micro-controller. To see about adding a torque mode motion.

I have some time. It will be a while before the planetary drive arrives. May turn out that 25:1 isn't going to be enough. I'll worry about that later.

[jcdammeyer]

I've been looking at my HP_UHU boards and have a question. (A couple actually).
My boards are marked Rev.10.b 12/2007

R54 feeding the VR16 reference pot has been shorted out and there's a 1N4148 diode to ground. This matches 1.0d+ drawing except there's an R20 2.2K replacing that R54 and now 1.0d+ has two trim pots for references.

There is one jumper on the top and some trace cuts near R55 and R16. Rev 1.0d schematic shows R16 is now connected to 15V instead of 5V. Why was that done? Something to change the behavior of the Slow Limit?

There are 3 jumpers on the bottom which look like they add the Rev 1.0d+ change of connecting the O.C. LED to pin 2 of the 4013 instead of the U9A comparator.

I never did change any of my boards to have the dual trim pots like in 1.0d+ or 1.0e.

I don't think you ever made any Rev 1.0c, 1.0d or 1.0e boards right?

[kreutz]

The latest PCBs I designed at the time were all Rev 1.0b 12/2007, the modifications on following revisions were made on those boards.