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Looks a little light duty for your project. Maybe you should just send that pile of parts to me and buy some real - man parts.
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As stated in a previous thread... See images!
It just about KILLED me to drag the ball screws in to my shop by myself, but I did it. Two per box, 3 meters long. Everything is VERY beefy and very well packaged. I'm beginning to think that 4x6" and 3x4" - 5/16" wall square tubing isn't nearly heavy enough for this machine. Damn, what have I gotten myself in to?!??
Prices of the parts are as follows:
50mm rotating ball nut - $682 Each
3 meter rolled ball screw - $1415 each (I bought two)
( I think a 4 meter screw was only about $1700 and change)
SHS30 - 30 mm rail prices as follows
1 Meter - Each $195
2 Meter - Each $390
3 Meter, - Each $575
Pre-loaded block, sealed, standard length caged ball for 30 mm rail, each $110
Pre-loaded block, sealed, long length caged ball for 30 mm rail, each $120
I'm using the long blocks on the X and Y, and the standard for the Z. Each rail has two blocks on it.
I think this stuff was an amazing deal. It's super heavy duty, and it got here in under two weeks from the time I placed the order... and it wasn't made with communist slave child labor either!
Andy
The Kontraptionist....
Looks a little light duty for your project. Maybe you should just send that pile of parts to me and buy some real - man parts.
you're going to need some big motors to turn those screws.
Tom
Nice parts.
Curious... how does that particular nut fight backlash?
Motors, nuts...yeah. OK so as far as that nut goes, I believe that this particular nut has a preload built in, which is good. The whole point of the rotating nut assembly is to just be able to have everything you need in one easy to deal with package.
Now the motors... yes they're gonna be big motors. Depending on my gearing(belt) ratios, the servos are calculated to be either 2 or 3KW for the heaviest axis. If I gear down more, I can use smaller motors. With the long lead of the screws I'm using, I'm using mostly torque. With a 1:1 ratio, 500 RPM gets me a thousand IPM rapid. Pretty fast. With a rated RPM of 2000, the machine is, in theory at least, capable of a 4000 IPM rapid. 3.7 miles per hour. OK.. Do I really need this? Probably not.
Sorry
it was the wrong button....
Yes... you definitely need this... we all need this. We all need to know that someone out there is building a router so large that it needs a Chevy small block mounted on it to turn the screws. Go get 'em!!!
Well, here's the beast. It's been a few years coming, but its finally paying for itself. Two 1KW servos on the X and Y, and a geared 750W on the Z. Goes more than fast enough. Scary fast in fact. I ran a porter cable on it for a few months until I couldn't handle it any more. They're great and all for making bird houses, but if you want to do WORK, get a real spindle. I spent $2500 at Eckstrom Carlson and got my 4.7 hp WITH a VFD and line reactor. Worth every cent, and I wouldn't hesitate for a second to do it again. The noise alone is worth the upgrade, not to mention the upgrade in horsepower and run-out.
The machine has been tearing through 3/4 veneered plywood at 240 IPM, full pass with a compression bit. Again, expensive tool, but if you run them right, they kick amazing amounts of ass and my clients are VERY happy with the finish. I've also been cutting MDF, mahogany, pine, spruce, Corian, 3/8 plate aluminum, acrylic, 1" PVC, Masonite, and the occasional bit of brass and foam. I can't complain one bit. This has been an awesome project.
The control is a Smoothstepper coming out of Mach3, going quadrature in to Automation Direct servos. Everything is currently running on 3 phase, but I made sure that all the components could take single phase if the need should ever arise. The moving part of the Z weighs a little over 150 lbs. It's balanced with a gas spring, and the servo has a 5:1 gear box and a brake, so it's all good in that department. The 1:2 ratio from the timing belt on all the axes is adequate. I might think about maybe a 1:3 next time, but the resolution and power are good enough, and even on the heaviest, longest running jobs, the 1KW's don't get more than slightly warm.
The cabinet has a PLC that talks with Mach3 over Modbus. The PLC handles homing, dust collector, and a few fault conditions. I'll eventually hook up a cycle start button, but for now, clicking is easy enough. I may also think about hooking up an analog module to the PLC to monitor servo and spindle loads on the screen, but I might just buy an RS485(or is 442? whatever.) converter and try to set up a multi-drop network and read everything over Modbus. I hear its a pain in the ass, but I'd be in to trying it if some spare time ever materializes.
I'd love to brag more, but I've got work to do. If anybody wants to ask questions, get a pep talk or some motivational feedback, drop me a line.
Best regards!
Andy Baker
ewest, nicely done!
I'm still learning CNC controls. Why did you choose to use a PLC and what kind of step pulse frequency are you using? Thanks.
The PLC only controls coolant and other non time critical stuff. Pulse, actually, quadrature, is handled by the oh-so-awesome SmoothStepper unit.
You should buy one.
Chose not to use step-direction because of electrical noise issues. Quadrature control is two waveforms out of phase with each other by 90º. This means no issues for pulse duration, etc. The waveform is identical to that supplied by a quadrature encoder. So far it's been WAY more reliable than step direction, but it depends on if your drive supports it. Automation Direct servos (Delta, same difference) can take quadrature, step/direction or CW/CCW pulse inputs. Most hobby grade stuff doesn't support quadrature. Too bad, so sad.
The PLC is an automationdirect DL-06. All I'm using it for is a better way to convert Mach3's signals to a more industrially friendly DC 24V signal. You can drive relays directly. Basically, and I know I'll draw a lot of flack for this, but the LPT port is kind of a sissy girl way of interfacing. It works great, yeah I know, but if you F up, then poof, there goes your motherboard. LPT ports were designed for printers,and yes you can hack them to run motion control, and for the most part it works fine, but if you screw up, they're toast. A PLC is a little more robust, and for NON TIME SENSITIVE SIGNALS, which are NOT your axis controls, like coolant, flood, mist, dust, tool change, blinky-light-for-needing-attention, start button, whatever, they're WAY better in that they put out an amp or two at 24 V and don't need an "simple transistor circuit" the only bummer is that they cost $200.
For homing, I don't use "home" switches in the normal sense, as these are clearly a bogus method when you have the "index" pulse available on your drive. Here's how it works. Homing of an axis commences. The axis drives in whatever pre-determined direction until the limit switch is encountered. The drive then slows down, and either reverses, or continues on until the encoder encounters the "index" pulse, then THAT is the home position - either the index before or after the home/limit switch. This means that the limit switch can have an error of +/- one revolution of the motor before it becomes a problem. As long as it hits "home" within one rev, the encoder will take care of the "fine" adjustment. This doesn't dismiss me from having to use good limit switches, it just lets me be free of worrying about if there's a chip or some other obscure artifact that causes that little tiny piece of metal in the home switch to click one way or another over the course of 0.001" which is asking a LOT. This is how the big boys do it, so this is how I decided to do it. Sadly, your drive has to support this feature. I think there are breadboards for this, and they'd be worth it. What this does is keeps you from having to worry about truly being home with your rig in case of a crash or power outage. Total no-nonsense, and it's saved me a TON of time on many occasions.
Cheers!!
Andy
Yeah using 10160 pulses per inch out of the SmoothStepper (did I mention... buy one)
Thats a 1:2 belt drive going in to 50mm/rev ball screws. They are huge mofos.
The Z uses a 5:1 gear reduction as well, since the axis weighs about 150 lbs, which is balanced by a gas spring, but still.... the gearing helps a LOT. It's still 10160 Pulses per inch though, because I introduce a 1:5 electronic gearing in the servo drive. It's just handy to have all the same number in Mach3.
Cheers!
Andy
Thank you for the info, Andy.
For the homing index pulse, this is available on Automation Direct AC servos? How do they do this with incremental encoders?
And fwiw, I've been on the waiting list for the Smoothstepper for a few weeks and they just contacted me recently telling me that mine is ready to ship.
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