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Degen's New Project

jcdammeyer said:
I bought the plans for a butterfly wrench manual system where the air valve is moved down to a place where it's reachable. An air cylinder pushes the wrench onto the draw bar. I think I posted some photos in another thread. I'll see if I can find it.

Here's the issue. Most of my tooling is Tormach Tooling; TT type but I have a number of other R8 tools. If you aren't familiar with the TT type it's a 3/4" R8 collet with the top ground flat. The TT holders are pulled up against the spindle as the R8 is pulled up. To release it takes 1/2 to maybe 1 turn of the draw bar to allow the tool to be pulled out.

R8 tooling can take 10 turns. If you turn the drawbar on the R8 TT collet 10 turns then out comes the TT holder and the R8 collet which defeats the whole point of the TT type.

What I've found is that I cannot control the Butterfly impact wrench well enough to make it turn 1/2 or 3/4 turn and then stop. This includes hall sensors and counting revs.

Here we go:
canadianhobbymetalworkers.com

Micro-controller controlled Pneumatic Power Draw Bar

This is a more appropriate place to continue the thread that started out asking about coil springs. https://canadianhobbymetalworkers.com/threads/coil-springs.3876/page-2#post-51519 Finally got around to casting the patterns today. Also since it appears that my AliExpress ordered pneumatic...
canadianhobbymetalworkers.com canadianhobbymetalworkers.com
Click to expand...
Well I your case I have a solution for you. Ditch the pneumatics and swap out for a Teknic Clearpath SDSK servo , you'll need to determine your torque required to pick accordingly (the 800 position encoder are more than sufficient for you. A simple controller to rotate 400 to 600 counts (1/2-3/4 turn).

These are just amazing. If you stall these thing you way over torqued them, like in the range of beyond 4x thier 100% duty cycle (don't ask how I know).

Expensive but worth every cent. I won't use steppers.
 
Degen said:
Well I your case I have a solution for you. Ditch the pneumatics and swap out for a Teknic Clearpath SDSK servo , you'll need to determine your torque required to pick accordingly (the 800 position encoder are more than sufficient for you. A simple controller to rotate 400 to 600 counts (1/2-3/4 turn).

These are just amazing. If you stall these thing you way over torqued them, like in the range of beyond 4x thier 100% duty cycle (don't ask how I know).

Expensive but worth every cent. I won't use steppers.
Click to expand...
Yes. The impact wrench will be replaced. But to keep things small I want a small reduction drive to boost the torque since speed isn't a big issue. A 3600 RPM motor with say 60:1 planetary reduction is one rev per second with a corresponding 60x increase in torque.

Make the motor current dynamically controllable and tightening torque can always be lower than loosening torque. I have an original UHU DC servo board supplied by Manjeet in India. It works well and the plan was to use it to be the drive for my little unimat spindle.
Test_UHU.jpg

Alternatively I had two of these running XY on the mill but the motors are huge since these HP_UHUs can do 150VDC and 20A way more than is required. Plus two more partially assembled.
HP_UHU.jpg
Finally I also have two of the GECKO G320 servo drives (unused).
www.geckodrive.com

G320X Digital Servo Drive - Gecko Drive

The G320X is our popular, low-cost DC brush type servo driver. The G320X has a power range of 18 – 80VDC and 0 – 20A meaning it can drive larger servo motors with ease. An internally closed PID loop ensures your motor will maintain position and correct for lost steps while under load. *For...
www.geckodrive.com www.geckodrive.com

However they all have the same disadvantage as would a stepper driver (I have two from Bergerda) in that setting the current dynamically is not possible. A Bergerda AC Servo drive (or any of the other Chinese brands) usually have MODBUS but that then requires a separate serial connection to set current and therefore torque.

With the UHU series I could wire a small dip relay onto the motor direction pin to parallel a second resistor in the current set circuit. So on tightening the relay is open and current set is through a single resistor. On loosening the relay is closed and a second resistor in parallel with the first to increase current and therefore torque. (Edit: I could do that with the GECKO too).

So what's holding me up? Casting the body and face plate of my harmonic drive (project #42) so that I can run my 4th axis and make my own gears for the reduction drive. Which is one reason why I started playing with the harmonic drives and other kinds of reduction drives.

But it's been another hot dry summer so casting is out for a while yet since I run the furnace outside. And now I have to wait 4 weeks before I can lift anything heavy after my TURP surgery on Tuesday.

I can wait. This is a hobby.
 
jcdammeyer said:
Yes. The impact wrench will be replaced. But to keep things small I want a small reduction drive to boost the torque since speed isn't a big issue. A 3600 RPM motor with say 60:1 planetary reduction is one rev per second with a corresponding 60x increase in torque.

Make the motor current dynamically controllable and tightening torque can always be lower than loosening torque. I have an original UHU DC servo board supplied by Manjeet in India. It works well and the plan was to use it to be the drive for my little unimat spindle.
View attachment 25487

Alternatively I had two of these running XY on the mill but the motors are huge since these HP_UHUs can do 150VDC and 20A way more than is required. Plus two more partially assembled.
View attachment 25488
Finally I also have two of the GECKO G320 servo drives (unused).
www.geckodrive.com

G320X Digital Servo Drive - Gecko Drive

The G320X is our popular, low-cost DC brush type servo driver. The G320X has a power range of 18 – 80VDC and 0 – 20A meaning it can drive larger servo motors with ease. An internally closed PID loop ensures your motor will maintain position and correct for lost steps while under load. *For...
www.geckodrive.com www.geckodrive.com

However they all have the same disadvantage as would a stepper driver (I have two from Bergerda) in that setting the current dynamically is not possible. A Bergerda AC Servo drive (or any of the other Chinese brands) usually have MODBUS but that then requires a separate serial connection to set current and therefore torque.

With the UHU series I could wire a small dip relay onto the motor direction pin to parallel a second resistor in the current set circuit. So on tightening the relay is open and current set is through a single resistor. On loosening the relay is closed and a second resistor in parallel with the first to increase current and therefore torque. (Edit: I could do that with the GECKO too).

So what's holding me up? Casting the body and face plate of my harmonic drive (project #42) so that I can run my 4th axis and make my own gears for the reduction drive. Which is one reason why I started playing with the harmonic drives and other kinds of reduction drives.

But it's been another hot dry summer so casting is out for a while yet since I run the furnace outside. And now I have to wait 4 weeks before I can lift anything heavy after my TURP surgery on Tuesday.

I can wait. This is a hobby.
Click to expand...
The nice thing about the SDSK's is that they are feed like a stepper, step and direction. Simple as pie.

As an example one of my units is about 240 in oz, 100% full rpm range from 0-1100rpm and 1050 peak @ 200rpm, I believe 10% duty cycle. Compare this with the same size stepper and the 240 is the peak before step loss.
 
Degen said:
The nice thing about the SDSK's is that they are feed like a stepper, step and direction. Simple as pie.

As an example one of my units is about 240 in oz, 100% full rpm range from 0-1100rpm and 1050 peak @ 200rpm, I believe 10% duty cycle. Compare this with the same size stepper and the 240 is the peak before step loss.
Click to expand...
How do these drawbar machines handle holding the spindle static? By hand I press the spindle brake while I tighten the last turn.
 
Degen said:
The nice thing about the SDSK's is that they are feed like a stepper, step and direction. Simple as pie.

As an example one of my units is about 240 in oz, 100% full rpm range from 0-1100rpm and 1050 peak @ 200rpm, I believe 10% duty cycle. Compare this with the same size stepper and the 240 is the peak before step loss.
Click to expand...
Servos are so much better than steppers.

All the newer servo drives are like that now. And size for the servos is way smaller with AC servos really being small compared to brushed type. These two have the same torque/RPM specs.

3000 RPM, 1.27 NM. (180 oz-in) 3.8 NM peak (540 oz-in).

For my heavier Y axis with the 4:1 that gives me 720 oz-in at 750 RPM way above what any stepper can do. On the X axis I have 3:1 so 540 oz-in all the way up to 1000 RPM. Looking at the current meter on the AC Servo drive display I'm not close to the max continuous current much less surge.
D8X_5544-TwoServos.jpg


And quiet.

But since I have a couple of those smaller 24V brushed motors rated at 2.7A and 3000 RPM and the drives I might as well use them.
 
PaulL said:
How do these drawbar machines handle holding the spindle static? By hand I press the spindle brake while I tighten the last turn.
Click to expand...
My Cheap House of Tools mill doesn't have a spindle lock. I used a WUT as described by Rick Sparber's article in Home Shop Machinist.

My now servo driven spindle locks the spindle so the impact wrench or even just wrench is fine. But I can turn it with a wrench and the V belts slip. Once I have toothed belts that will be less of a problem. In fact I could probably drop a lock down over the drawbar nut and tell LinuxCNC to turn the spindle half a turn since it now too runs step/dir for control. But then once again, have to have LinuxCNC running to make it work.
 
Seems Princess Auto is putting a refurbished electric ratchet that is 12V and rated at up to 22 ft-lbs. But the price is $49.95 w/o tax. Easy enough to replace batteries with a 12v power supply and a controller that limits current and therefore sets tighten torque to 18 ft-lb, loosen to 22 ft-lb. But I've never used an electric ratchet. Don't want to spend $50+ to find out it's somewhat useless. Already have an air ratchet that I rarely use.

Anyone have experience with electric ratchets?
 
Thyssen, commercial orders and for my products. Most should be used up by mid Sept, with about 30lbs of a shavings and 30lbs of scrap.
 
Last edited:
PaulL said:
How do these drawbar machines handle holding the spindle static? By hand I press the spindle brake while I tighten the last turn.
Click to expand...
Sorry didn't answer this correctly I use a butterfly wrench to tighten and loosen, no spindle locking required. I am going to convert it to a draw bar tightener/loosener, but have to do some mod to the system (time permitting).
 
Degen said:
You love my shavings and scrap.
Click to expand...
My shavings go to recycling. They mostly oxidize in trying to melt them. But scrap is always good. The big problem is that 6061 isn't that great a casting alloy. The plan this fall is to melt a bunch, raise the temperature way above pouring temperature and dissolve some copper into it. Even just 5% makes it more machinable.

But it has to be dissolved and then cooled back into ingots. Otherwise way too hot to pour. As it is I still have a lot of issues with porosity in my castings even after degassing before pouring.
SpindlePulleyBuild-2.jpg


I wouldn't be surprised if this even affects the pulley balance.
 
jcdammeyer said:
My shavings go to recycling. They mostly oxidize in trying to melt them. But scrap is always good. The big problem is that 6061 isn't that great a casting alloy. The plan this fall is to melt a bunch, raise the temperature way above pouring temperature and dissolve some copper into it. Even just 5% makes it more machinable.

But it has to be dissolved and then cooled back into ingots. Otherwise way too hot to pour. As it is I still have a lot of issues with porosity in my castings even after degassing before pouring.
View attachment 25625

I wouldn't be surprised if this even affects the pulley balance.
Click to expand...
Keep me informed, interested in your results.
 
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