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About LinkBacksHave you ever tried dampeners to resolve the resonance issue with the HobbyCNC controller? I wouldn't be opposed to practicing my new machining skills by building a set of these.Originally Posted by DeusExMachina
My take on a stepper damper
Have you ever tried dampeners to resolve the resonance issue with the HobbyCNC controller? I wouldn't be opposed to practicing my new machining skills by building a set of these.
My take on a stepper damper
Well, you can try. This is a big, expensive project though. I mean if you don't have the aluminum stock of this size lying around, then buying that alone can cost you a bundle. The G540 is only $299 here, and it's excellent in many ways OTHER than just resonance suppression. There's like half a dozen reasons that could come up that'll make you want to replace an obsolete controller like this. The only reason to go with it would be if you already HAD a fully working HobbyCNC controller, power supply, and case built that you got with the mill and want to make it work better with dampers. If you're gonna buy a controller, where you have a choice, don't buy that one.
Actually I had a couple of dampener ideas:
1. Mine came with hollow knobs. The interior had 3 ribs which separated the interior into 3 chambers. By filling each about 2/3rds full of lead bird shot (cut open some shotgun shells, carefully), cover with a rubber pad then a plate of acrylic, it could be a fine damper.
2. Sorbathane urethane pad. That stuff can be really good. If you cut an interior wheel with a set screw, a spacing for the Sorbathane pad to be wrapped around, then an outer mass with handle knurlings, and proper compression holding it together, it should be a fine damper. Less noisy too.
I agree. Dampening should be done by the drive. Helluva lotta work and material saved. Not to mention frustration. Trust me. Been there. Done that. Gecko's rule for the price, function, and capabilities.
Listen to Leeway, buy gecko's, price, features, customer service, they are indeed unbeatable.
Amplexus Ender
Are you referring to this article?:
http://www.jeffree.co.uk/pages/taigcncpt2.htm
Cheers.
Yes that's it. Thanks for looking it up and posting it.
The other important thing to consider is not only the motors rating but how well it matches the power supply and stepper driver. I carefully chose the motors, power supply, and G540 to carry on my website as they work great together.
Jeff Birt
Looks like a bunch of obsolete info. First off, with higher voltage drives, the inductance is really not a limiting factor at high speed.
Second, this is pre-Gecko stuff. The Gecko can drive 318oz-in motors way over this "maximum" of 52.5ipm. It can lift the headstock mass at high speed too. The problem isn't specifically "inductance" making a hard limit on speed, it's midband resonance. In fact even installing dampeners would probably have given him radically different numbers in his testing.
Also not all high torque motors are high inductance anyways. Not all low torque motors are low inductance.
He did some experimenting, I respect that, but he didn't understand a lot about what he was looking at and his overall conclusion is completely wrong: Taig mills DO benefit from motors over 140-160oz in. In fact they require them to perform well. 282 oz-in in a good "minimum" and that will run the mill "faster than you'd probably ever really want to go". The 318-382 oz-in might be better for lifting the heavy headstock at crazy high speed but who knows. Well I put the 318 on there and it lifts fast too. But who actually needs to lift at 60ipm? It's not gonna save much time because the project time is mostly spent in the work and can't plunge at 60 ipm into much of anything.
I respectfully disagree.
The laws of physics are never out of date.
The difference in inductance between a 166 oz-in motor and 276 oz-in motor is such that even at 48V the larger motor will only provide more torque up to about 3 IPM on a Taig. The acceleration is also slower.
With 166 oz-in motors you can do 40 IPM rapids all day long, it will do closer to 60 IPM but there is little advantage as it would only take 2 seconds or so off a full X axis travel. Most of your time should be spent cutting which will be much slower than rapid speeds so there is no advantage to using huge steppers, 80 volt power supplies and such on a Taig mill.
The great thing that folks can choose the best route for them.
Jeff Birt
Jeff-Birt,
Not all Taig users cut metals or use slow turning spindles.
Some of us have 35,000 rpm spindles and cut wax at 50-60 ipm on a daily basis.
There is a big advantage in having the ability to cut at 60 ipm or even faster depending on the material being machined.
Jeff...
Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.
WOW where did you get a 35K RPM spindle? Link please?
Arrrggg...somehow the main point seems to be getting lost. The traveling time for the full 12" of the Taigs X axis would be as follows:Some of us have 35,000 rpm spindles and cut wax at 50-60 ipm on a daily basis.
40 IPM = 0.3 minutes
60 IPM = 0.2 minutes
So the difference is six seconds, discounting the time taken for acceleration and deceleration and presuming that your just going to run the X axis over its full length of travel in one shot. The Y axis has about half the travel so you can estimate the time difference as well.
If your doing any 3D profile work then the real difference will be less as the machine will be spending a lot more time accelerating and decelerating.
So if your only doing long straight runs in wax with a 35K RPM spindle then the additional speed might be of benefit. The thing is that 99.9% of folks with a Taig don't just cut wax and they don't have a 35K RPM spindle. For all these other folks the additional speed only adds additional wear and expense.
The point I am trying (in vain) to make is that there is little to no advantage to 99.9% of folks in putting large stepper motors on a Taig. Most of the reason folks do so is because they think a bigger motor has to be a better motor, or they try to find a motor that matches the max specs of their stepper driver.
The stepper motor needs to match the machine, the type of work being done, the driver and the power supply.
Jeff Birt
Jeff Birt,
For 99.9 percent of the designers or jewelers that use Taigs, larger stepper motors make an enormous difference in the time it takes to machine a part.
The issue is the torque fall off of a stepper motor as the speed increases.
It may save hour's per part depending on the size and its complexity.
The benefits would apply to machining foam as well as other rapid prototype
materials.
Jeff...
Last edited by jalessi; 06-30-2009 at 04:17 PM.
Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.
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