Mill

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kb1gtt
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Mill

Post by kb1gtt »

So they put the mill in the garage. Now I need to CNC this guy. I'm making progress on a servo system.

Current plan is to use LinuxCNC to generate step and direction pulses. Then use a local Coreless DC motor with encoder to servo the local motor. I'm currently layout out a board for the local servo. I call this combined Stepper and Servo, Stervo. See attached.

It currently has a 3 phase motor. I might have a lead on a single phase motor. Either that or I have VFD's so I could use a VFD to take my 220 single phase and generate 208 V 3 phase.
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ecologicalleds
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Re: Mill

Post by ecologicalleds »

SWEET! I was going to get one of those, but decided to build my own system due to my light rail lengths I build.

I tried using linuxcnc, and spent about 6 months worth of effort, even compiled my own versions. very disappointed in the functionality and reliability. very slow.

Ended up buying a csmio ethernet 6 axis controller, added 5 fiber optic channels to it for encoders and use mach4 for the software. Could not be any happier with that choice. I use my gaming laptop for the cnc computer also. Used hybrid 1200 nm steppers and 5000w vfd drive/motor from china. I'm only 3 axis right now, but have the parts to build the other two rotary axis's then I will have 5 axis capabilities(I don't need 5 yet).

Just bought a 1000w output power medical co2 laser unit to install inline with the routing head(need to adapt water cooling to the laser head).

I would post a pic of it, not quite sure how to do that yet.
stefanst
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Re: Mill

Post by stefanst »

A friend of mine, who has a machine shop, has some linear encoders he may let go for cheap.

Edit: Nevermind, I see you already have a numerical readout.
Also, a lot of machine shops run spindles off a simple static converter.
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kb1gtt
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Re: Mill

Post by kb1gtt »

Pictures can be added via attachment. Perhaps needs forum permission.

I agree, that LinuxCNC is hard to deal with, but it also allows you under the hood. I also know that many people poo poo Bridgeport CNC, I understand that a Bridgeport is not a good CNC, slow and not accurate, etc. However my primary goal is to NOT turn the crank the wrong way, and to NOT dial in the wrong number.

I'm missing the optical Z axis. I plan to add that some day. For now I want to get X and Y moving, then I want to get the optical DRO into the LCD screen, then Z control over the bed (not quil) then Z DRO, then no plan is complete with out world domination.

In the near future I'll be looking to learn how to get the optical pulses decoded by LinuxCNC. For now I'm looking for open loop bed control.

I'm also starting with a wrong sized motor, but I figure meh, it's low cost and I can upgrade the motors easy enough later on. For now I have a pile of 22CL-3501PG purchased from ebay for like $5 each. They are 120 RPM with Stall torque: 16.5kg*cm (230 oz-in) and Continuous torque: 5kg*cm (70 oz-in). I plan to 3D print a gear that attaches to the handle, such that I get a gear down ratio from the motor shaft to the handle. I know that this is way undersized for a stepper, but when I make it servo, it won't skip steps like a stepper will do. So I can cut into the torque limits a bit more. As well Bridgeport are missing rigidity, so you have to run them with a light cut any how. AKA light cuts means less torque.

The Stervo board I'm laying out is using the BTS7960, which can drive 40V at 40A DC motors. So I'll have the abilities to increase the abilities. For now I'll start small and cheap. I also plan to allow a connector such that these motors can be selected with different RPM's such that you have some flexibility. I would like to find a better motor, preferably coreless (brushless) However for now I'm planning on these motor options.
https://www.servocity.com/motors-actuators/gear-motors/heavy-duty-gear-motors/premium-planetary-gear-motors-with-encoders
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kb1gtt
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Re: Mill

Post by kb1gtt »

Oh, I've also been disappointed with the lack of progress in LinuxCNC. I see 3D printing which does all sorts of crazy predictions and reasonably accurately determines the amount of time it takes to print, and the amount of materiel that will be used. I don't see why LinuxCNC can't allow me to enter some parameters like what alloy I'm cutting, and how many teeth I have on the cutter, etc, then predict the torque or horse power required for that cut. AKA I can determine the peak torque, and make sure I'm below what the motors can provide. However that does not seem to exist, which is a bit disappointing. I see many features like that which could be really handy. However free and lets me under the hood, so I'll give it a try.
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ecologicalleds
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Re: Mill

Post by ecologicalleds »

heres a few pics of my setup.

i really wanted to use linuxcnc.

i have not had problem with missing steps with these hybrid setups, if they did, it goes into e-stop. the only reason i know that is due to my stupidity. i did not tighten a 13mm carbide fully. ten minutes later at 10,000 rpm, 2500mm cut speed she came loose and cut almost in half a large chunk of 6061 i was milling. i may have even got to the e-stop button before the step error.

i will look around and see if i still have the box of left over parts from my build, but that may have gotten tossed when i did major cleaning. i know i have some of the pci cards for linuxcnc, bought a lot off ebay couple yrs back. i also have the huge 220v 8 core poweredge 6850 server i was going to use for the main controller, hardest thing was getting the driver right for the display. but it worked.

i will use a r/c style of esc and custom wound motor for the 5 axis head. (r/c esc and motor can be powered via a modded server power supply)
Attachments
rotary encoder modded for fiber optics
rotary encoder modded for fiber optics
IMG_20160111_175509.jpg (3.05 MiB) Viewed 8179 times
under the hood of the csmio-ip, added fiber optic receivers
under the hood of the csmio-ip, added fiber optic receivers
IMG_20151230_115457.jpg (3.7 MiB) Viewed 8179 times
some 6061 parts i cut, not bad for first go at it
some 6061 parts i cut, not bad for first go at it
IMG_20160920_155619.jpg (1.42 MiB) Viewed 8179 times
testing
testing
IMG_20151119_195631.jpg (4.15 MiB) Viewed 8179 times
control panel, before i added the 110v relays for the vacuums
control panel, before i added the 110v relays for the vacuums
IMG_20151124_104124.jpg (3.47 MiB) Viewed 8179 times
vacuum table completed
vacuum table completed
IMG_20160217_114358.jpg (3.11 MiB) Viewed 8179 times
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kb1gtt
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Re: Mill

Post by kb1gtt »

When you say hybrid, do you mean stepper with encoder? I understand those exist as the next upgrade to a stepper. Basically it lets you know when you skip a step. I kind of do not like steppers with feedback, as the steppers are larger, and the frequencies are much higher. Higher frequencies makes for more problems with tank circuit resonance.

Looks like a nice old building basement, which has been spruced up with some nice shinny CNC equipment.

I usually have trouble finding the e-stop when things go wrong. I know it all happens in a blink of an eye, but it feels like hours while you moving your hand to the big red button. Some times I don't make it to the button, my feet some times loose traction in the slippery brown stuff that suddenly appeared around my feet :roll:

I hope I can make LinucCNC work. I just got my replacement wifi USB devices. I apparently got the good ones jumbled with the bad ones, and then lost the good ones. So I now have more good ones, and I get to attempt to make it go again.
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ecologicalleds
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Re: Mill

Post by ecologicalleds »

Big old home built in 1896 with 2 1\2 foot foundation and brick work.

You barely have time to react when things go wrong, for sure. ;)

They are called hybrids from the manufacturer(hbs86). I think the "hybrid" part is how the stepper and stepper driver pid controller loop " acts" like servos with feed back.

You definitely need good shielded wiring. Differential signaling helps a lot. I used cat7 Ethernet cables 30ft long to each driver from the controller. When I'm milling, I rarely hit 5000mm/minute federate, so not clicking super fast.

The encoders I added for indexed homing, position indication, and rpm. The fiber optics so I can easily split my encoder signals(for tracking position with arduino or something, so I can back track if issues) and get rid of some delay issues with the csmio indexing 4000ppr signal.
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Re: Mill

Post by kb1gtt »

Does the hbs86 have a PID setting? Typically those just verify that you made it to your desired position. Some will continue to drive the stepper if it does not measure that you reached your target, and some will turn off power to the stepper when you reach target, such that you save on power, and have less of a chance of overheating the stepper.

On the board which I'm calling Stervo, It gets added to the coreless DC motor, such that you do not need shielded wires, or a control module in an remote enclosure. Also I'm planning for an optional fiber optic buss to the brain PCB. I don't know if it will be fast enough of a bus for this, but it might be. It has been some years sense I last use the below item.
http://www.digikey.com/product-detail/en/IF-E10/FB104-ND/3724

I'm also planning for CAN, TTL, and opto-isolated inputs. So I should have many options for LinuxCNC to make this go click click click.
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ecologicalleds
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Re: Mill

Post by ecologicalleds »

I have these db25 cards, cables, and nema23 steppers you could have, unsure of torque rating(2 are single shaft, 2 are double shaft. Have not found the other box of misc parts, yet.

I did not want to use a separate controller and pc, but that's where I ended up.

Yes, they have pids I can change along with, amps, duty %,speed, resolution, gain, dir, error, holding power, and other things I haven't touched. I will test this, but I'm pretty sure if she missteps, set to estop everythin.

The controller will also estop if indexing signals are off or missing.

Servo drives would be my next step up, but I'm very happy with my setup right now. If I were, most likely build another larger mill.
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ecologicalleds
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Re: Mill

Post by ecologicalleds »

I stand corrected, sorry about that. Leadshine Hybrid servo drives and easy servo motors.

Each motor has two encoders, one for the drive, and one I added for indexing/position tracking.
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