[nateman_doo]

The only helical I have is a SS one. It came with the ball screw.
My other couplings are all Oldham style.
No need to fiddle with the coupler when removing the motor.
Just real nice to work with.

I have oldhams on my X2 and the acetal wears giving them their own backlash. I do like that you can just take the motor off with them too. I just don't see anything wearing out with the helical type. I only see them as being weaker connectors, but with linear rails, thats not a problem.

[LeeWay]

I have heard of a lot of aluminum helical couplers failing. If I was to switch, it would be all SS ones. Little more heavy duty.
The ways with linear rails may prvide little friction, but you start loading some weight on an axis and there is still some mass to it. Any kind of quick direction change will all put pressure on those couplers. I would not use aluminum on anything as far as helical couplers go. Maybe on my 3D printer.

I haven't seen any wear on my Oldhams yet, but I know it will eventually. I have spare discs waiting on that day.

[nateman_doo]

My oldham discs are probably going on 3 years of usage so I guess the stuff doesn't last forever.

I agree that the aluminum ones are light weight. I want to give them a fair shot. I tried them and they failed me in my X2. I will try them out, and when and if they fail I will consider the stainless, or go to the oldhams.

Here is the the table sitting in the enclosure:


Just a "here is what it looks like so far" picture.

[vcatalasan]

Wow that is a back breaker putting that machine in its place! Looking good!

What electronics will you be using for movements?

[nateman_doo]

Wow that is a back breaker putting that machine in its place! Looking good!

What electronics will you be using for movements?

I have moved it in and out of there a few times. I am in pretty good shape

Keling steppers, gecko drivers, and the C11 BoB from CNC4PC

[scleaf]

There is no way I would be able to build this as strong as I want without anchoring it to the house foundation. I have no intention to move the machine. In fact I tore down a wall in the basement and moved it over expanding my shop just to accommodate this build.

The base will be hundreds of pounds. In fact with the weight of the four slabs of 4x4x3/4" MDF its already pretty solid. Toss between 400 & 800 lbs of concrete, and anchor it into the house and its a recipe for rigidity. Also the aluminum extrudes of the gantry structure will be filled with concrete to deaden vibration

The house is settled in enough, its over 30 years old. I already have my X2 semi secured to the house, but in order to get it more rigid I have to tighten the gibs which gives me more backlash. I am sure if anyone hasn't noticed yet I am not a lover of gibs.

Then I would say you have a solid foundation.

I personally have a KentUSA CNC with an Acu-Rite MillPwr 3 III control. (Bridgeport Clone with 3 axis control) It weighs 3700 lbs. I had to move it off the HD Trailer I rented to go pick it up in San Francisco and haul it to Sothern California. When we moved it into the garage from the driveway it was on three steel pipes with an electric winch attached. pulled it 25 feet, 6" at a time. It was quite the event but I can move it around.

I hope to some day make my own 4th or 5th axis mill. For now I am going to make me a 4th axis indexer/lathe attachment so I can cut gears and rotate the parts for indexing when needed. The funny thing is many of you out there are making mills on mills. Who is making parts for consumption? haha

Your build looks awesome, keep up the hard work, use a lift or cherry picker when moving it, helps the back and is safer.

Best regards,
Vince

[nateman_doo]

I was guess the entire weight will be just under 1500 lbs, but it will be more then 1000 for sure.

Wire arrived today:


Wire threaded into the cable carrier


Close up of the cable:

6 wires. 4 for the motor, and 2 for the home/limit switch. One wire per axis.

[SCzEngrgGroup]

Running home/limit wiring through the same cable as the motor wires is a recipe for VERY flaky operation. The home/limit wiring should be in a completely separate cable, and shielded. Running the two cables side-by-side through the "chain" is fine, if properly shielded.

Regards,
Ray L.

[nateman_doo]

Why? Its just a pulse of ground to trigger it.

[SCzEngrgGroup]

Why? Its just a pulse of ground to trigger it.

The motor signals will induce noise in the home/limit wires that Mach3 will interpret as valid home/limit signals. The result will be unreliable homing, and random limit triggers even when you're not anywhere near the limits.

Regards,
Ray L.

[691175002]

Ray is right, it is bad form and has the potential to cause false triggers.

You can get around it by using low resistance pullups/downs, capacitors and other noise filtering.

[nateman_doo]

Is that the "driver watchdog activated" or whatever random fault i get in Mach on SUPER random occasions?

What is a low resistance pullup/down? where would the noise filtering go, in the home wire? I was only planning on using a single home wire and have the machine touch and send a single ground pulse down the wire. Instead of a traditional switch, use those lathe turns of delrin and aluminum so when the machine actually touches it, it will be home.

[Fastest1]

Start with a good star ground. IME This will do more to prevent noise issues than everything else combined. None of the other techniques helped me at all til the V- of my power supply was landed on the star ground. Now I can't get it falsely trigger no matter what I do.

[nateman_doo]

The table is completely electronically isolated from everything, as well as the gantry structure...unless there will be a small ground through the motor wires themselves into the chassis of the motor into the table & gantry themselves.

trying to figure out of thats a good thing or not.

[DRock]

So how do you guys properly ground your electronics? What do you do with the cable shielding?

I am trying to take all precautions to reduce noise so this info would be extremely helpful.

Thanks!

[SCzEngrgGroup]

So how do you guys properly ground your electronics? What do you do with the cable shielding?

I am trying to take all precautions to reduce noise so this info would be extremely helpful.

Thanks!

For safety, securely ground the machine itself to the AC ground. Where the AC line comes into your E-Box, connect it securely to the metal of the E-box case. All other grounds should be connected to this same point. If you're putting everything on a metal panel or plate, ground that panel. Never, never, EVER daisy-chain power or ground wires to multiple devices. Run separate wires from the power source to each device. For sensitive logic-level signals like limits, use shielded cable, and connect the shield ONLY at the BOB end, NEVER at the machine end. Keep the un-shielded sections as short as reasonably possible. For better noise immunity, use 12V or even 24V for things like home and limit switches, then use a resistor divider to drop the level down to an safe level for the BOB input. In reality, even 5V signals will work fine, if you follow the other rules, and use a stiff pullup resistor to 5V (200-300 ohms) at the BOB input. Follow the above, and you should never have a problem. I have ALL my electronics - computer, KFlop, Modbus board, 3 BOBs, four servo drives, a stepper drive, two servo power supplies, 5V, 12V and 24V power supplies, VFD, PWM speed control, several relay boards, pendant interface, etc. all in a single 24" x 24" x 12" enclosure. Encoder and home/limit cables are Ty-wrapped to the motor drive cables for their entire ~15 foot lengths. Limits and homes all running at only 5V. Haven't had a single "glitch" in four years.

Regards,
Ray L.

[nateman_doo]

I thought home switches received a ground pulse, as in when the bob received ground, then it triggered a home state. If thats the case, how would it be any problems? I don't question your experience, I am just trying to visualize it.

[SCzEngrgGroup]

I thought home switches received a ground pulse, as in when the bob received ground, then it triggered a home state. If thats the case, how would it be any problems? I don't question your experience, I am just trying to visualize it.

Home and limit switches can be wired active high or active low. Either will work. The problem is, as I said before, logic-level signals can pickup noise from other wiring in the system, particularly motor wiring, which radiate a lot of electro-magnetic energy. That energy can induce a signal, high or low (more often, just changing randomly, often at high frequency), on a home or limit wire where there shouldn't be one.

Regards,
Ray L.

[691175002]

Your BOB is not really detecting ground, it is just detecting low.

Your BOB will have a resistor connected to the input to pull it to high, or 5V.
Connecting the input to ground overpowers that pull up resistor and brings the signal low.

Your original "clean" signal might end up looking something like this if it is unshielded next to the motor wires.



The above is of course a pretty brutal example. The actual amount of noise seen depends on a bunch of different things.

[amishx64]

If you are worried about getting more shielded wire, etc it's not a big deal and it is cheap.

CAT6E networking cable is shielded.
Common telephone cord is shielded.
Some alarm system cable is shielded.

You should be able to just run a second length of wire dedicated to switches along the motor wire (assuming small enough noise).