G0704 CNC conversion

[Wizard69]

I would love to go with a brushless motor but they cost too much so I'm probably going to pick up a 1 to 1.5hp three phase motor and VFD. I found this one for sale locally on Craig's list, what do you think?

The drive is fairly big and open framed. The open frame drive will require an electronics / electrical enclosure suitably sized. This is an additional expense. Ideally you want a big enough enclosure to contain all of the machines electrics.

I mention this because the drive looks physically large. As far as the manufacture goes they have made good product in the past.

Here is the spec sheet on the VFD. I'm still trying to find specs for the motor but I think its only 1715 rpm from what I can read on the motor plate.

I don't have time today to look into the specs. You do need to make sure it is a proper match to the motor.

A 1715 (odd value ) RPM motor is probably a good thing. That should be a 4 pole motor which helps with torque at lower speeds. The motor should be capable of at least 3400 RPM and probably a bit over that. You should look for maximum rotor speed spec. The flip side here is that you can't achieve the higher speeds unless the drive is capable of operating beyond a 120 HZ. Most drives can easily go up to 120 HZ but you need to verify that as older drives may have limitations.

You should be able to get really good performance out of this motor and drive from 800 to 3400 RPM and probably well below 800 RPM.

Let me know any thoughts as I would be purchasing it in the next day or two! Thanks!

Dale P.

If you have the motors specs, especially its frame size, get out the drawing tools and mock up a paper / cardboard flange and see how it fits on the mill. Physical space is the number one reason for dismissing a 3 phrase motor upgrade. If you can't fit the motor in place obvious this would be a bad buy.

 

[Wizard69]

Just talked to the guy on the phone about the motor and drive for sale and he said he works for Tormach and this combo was used on their machines for several years before they moved up to digital drives. So I'm glad to hear it's been proven for use on milling machines with hours of continuous use.

If the drive is properly sized to the motor i don't think you should worry. Modern versions of these drives anyways are very reliable. At work we probably have dozens of different drive manufactures represented with probably hundreds of drives running right now. The failure rate is extremely low once you get past infant mortality. I don't think I've replace one in several years now.

Guess the only thing I worry about is the motors RPM. I see some people are going with 3000 RPM motors but this one is only 1715 RPM. With the VFD I should be able to get a lot more RPM since it can be turned up to a higher frequency??? I wonder what pulley ratio are guys between the motor and spindle?

Why worry? Seriously you want a 4 pole motor in these situations so that you maintain some decent low end torque. The drive doe s will tell you what the maximum speed potential is. If the drive can do 120 Hz you will be able to hit 3400 RPM. If the drive can go beyond that then you get faster speeds. Just make sure you stay under the motors max rotor speed spec.

Dam, too many questions to find answers to. I just want to build the machine, not engineer it.



Dale P.

Like it or not you will have to do some engineering.

As far as pulley ratios that depends upon what you are doing with the machine. You may be able to get buy with 1:1. This is again a bit of engineering but it pays off in the long run to think about what you expect out of the machine. Depending upon the drive and your low speed needs, it might pay to have two belt ratios. In other words a step pulley. A 50% reduction in speed might be a useful ratio.

This is still a small mill so I'm not too certain that extremely low spindle speeds will be all that useful. That is can the machine handle a shell mill of any size well. Is there any other tooling you need to run at a low speed? In the end nobody can say for sure what you need performance wise. If you expect to machine a lot of wood, plastic and aluminum materials a focus on higher spindle speeds is in order.

 

[ibuildstuff4u]

Thanks for all the replies! It's nice to get a second opinion when working on a project.

I was happy to hear from the seller that the motor and drive were originally designed for a CNC milling machine and that they are already sized to work with each other. I think the Tormach machines run at 3k or higher spindle speeds, but who knows what gear ratio they are running. A quick look at the drives specs says, "Adjustable 4 to 16kHz switching frequency: Higher frequencies result in audibly quieter motor operation. Lower frequencies produce less electrical noise. Choose the right setting for the environment."

The drive is an open frame design, but I have a nice 14"X16"X8" Hoffman enclosure for all of my electronics that should be able to fit the drive as well so that shouldn't be a problem. If I remember right the motor is a C56 size and I have seen a few examples on the web showing other G0704 mills using the same size motor. However it is a tight fit and this is my largest concern with using this motor. Guess if I buy it and don't like it I could always use it on my drill press or band saw. Would be nice to have adjustable speeds with just the turn of a pot switch instead of changing belts.

99% of the material I cut is aluminum so low end speed/torque isn't really needed. If I can hit 3K with my spindle I would be happy for most of the work I do.

Thanks again for the help.

Dale P.

 

[ibuildstuff4u]

So a few things have changed.

I really been thinking of up grading to Mach 4 in the near future and came to the realization that this USB controller will only work for Mach 3. I really like the motion control boards that PMDX sells but they only work with Mach 4 so if I get one I will have to up grade to Mach 4 right away. PLUS I have a CNC lathe that has a parallel port breakout board so it also needs a motion control board to get it up and running.

SO... after a lot of thinking today, I ended up pulling the trigger and ordered a PMDX-424 motion control board with the 407 spindle control board for the milling machine build, and a PMDX-410 motion control board for my lathe. I also bought a copy of Mach 4. With this being said, I'm broke and won't be able to buy a new spindle motor for a while.

I really liked the price of this motor and drive combo and it was located in my state. As a bonus my wife and I are traveling to that city this weekend for a small vacation and I could have easily picked it up saving shipping fees. Oh well, guess it wan't meant to be.

Dale P.

 

[ibuildstuff4u]

Trying to get my Mach 4 license and it has been very stressful so far! The coupon code process has many steps and I think I just messed up. I hope I didn't just throw out $200. As an added bonus, $400 dollars worth of motion controller cards was suppose to be delivered to my house Saturday and the tracking info says the address was undeliverable and it's being sent back to the sender if possible!

I spent $600 dollars and have nothing to show for it. My blood pressure it through the roof right now.

Dale P.

 

[ibuildstuff4u]

Ok, got Mach 4 to work. What a pain in the butt. It took two days to get my coupon code after I paid for it, and then I had to jump through several hoops to get it my license from New Fangled Solutions. Not a fun process.

Now I just need to find out about the missing package.

Dale P.

 

[RonGinger]

It would be useful if you sent a note to [email protected] and explain what problem you had in getting the license. You had two vendors involved here, PMDX and Newfangled. I know the Newfangled system works very easy, we had 12 coupon codes in the last mill build class and they all worked very quickly. I also know there is no company any better at customer support than PMDX so I am sure your package will get sorted out.

 

[ibuildstuff4u]

Just seems like a lot of steps to get a license code up and running. I know it's to prevent people from stealing their hard work, but in the end its the customer who ends up having to do a lot of extra steps to get the product that they paid for. Just a bummer that software companies have to do this to protect their work.

I thought I messed up my coupon code at first and was pretty stressed out till I was able to get it all working. There are lots of warnings saying that you only have one shot with the code! You have to read the instructions very carefully.

PMDX mailed out the package using a printed label from Pay Pal so it looks like the post office is to blame at this point. I'm wondering if the address label was damaged in transit? I tried to call the post office today, but realized that it's president day and they aren't working. $400 is a lot of money to get lost in the mail, hopefully the package will be found and delivered to me. I actually at the point where I need the boards to move to the next step and put together my control box. I'm hoping to have a running machine in the next 30 days.


Dale P.

 

[M130]

Hello, I have just taken a look on your build tread and I must say i'm impressed of your build. Your build look much more tidy and nicer than mine :bow:
I hope you don't mind I show you a picture of my electronics encosure here:hDe:
Regards Morten

 

[RonGinger]

Nice job. What is the box? It looks like it has hinges for a cover. Ive been looking for a good size box for that kind of control but have not found anything, except very expensive industrial boxes.

 

[canadianhorsepower]

We all have our set up, here is a picture of mine
all build in house driver and all. The face plate is also home made the holes
on the left is a matrix with LED showing the activity of the axes and errors from the driver
the two panel meter are top RPM bottom Ammeter of the spindle,
Enjoy

 

[blighty]

nice build canadianhorsepower, i see you stuck your pc in there as well. i thought about doing that, then got into all the noise debates from people that say you should to ones that says you shouldn't, the main decider for me was the extra £60 for a bigger box.

 

[M130]

Nice job. What is the box? It looks like it has hinges for a cover. Ive been looking for a good size box for that kind of control but have not found anything, except very expensive industrial boxes.

The box is actualy a circuit breaker box used in norwegian houses in the 60th and 70th. It was just something I had lying around.

 

[ibuildstuff4u]

Yes! My package finally came!!! Post office must have lost if for a few days because it just showed up even though the tracking # said it was undeliverable as addressed. There was absolutely nothing wrong with the package and address label.

I was hoping to move forward and start working on the electronics, but I realized that the enclosure I bought was going to be too small for everything that I want to put in it. I bought a nice Hammond 14"x16"x8" box but ended up ordering a 20"x20"x8" box and hope to have it by the weekend. I decided to go with a three phase spindle motor for the mill and wanted to have room to put the inverter in the same box with the stepper drives. My goal is to make this box easy to move so I can use it for a future CNC router build and just share the control box between the two machines.

Dale P.

 

[canadianhorsepower]

nice build canadianhorsepower, i see you stuck your pc in there as well. i thought about doing that, then got into all the noise debates from people that say you should to ones that says you shouldn't, the main decider for me was the extra £60 for a bigger box.

Thanks,
yes the PC is in. I don't know why people are so concern with noise
and I don't mean music
Keep the power supply away and wires as short as possible and you're in business. One experiment I get my students to do in class is taking a small
OP AMP circuits with no noise at all then take one resistor mount it away 12 inch using wires. That produce so much noise can't see anything on the scope

 

[blighty]

Keep the power supply away and wires as short as possible and you're in business. One experiment I get my students to do in class is taking a small
OP AMP circuits with no noise at all then take one resistor mount it away 12 inch using wires. That produce so much noise can't see anything on the scope

i should know about this, as i look for stuff that shouldn't be there for a living. i'll get the hang of it one day

 

[ibuildstuff4u]

It's been a few weeks and I finally have my CNC control box done and ready to power up. Tonight I ran a new 240 volt outlet to the machine so I'm all ready to power it up and test it out.

I ended up adding an outlet to the bottom of the control box which is controlled with two digital relays so I can use it to turn on and off a coolant pump, shop vac, or something else.

I'm hoping to build a CNC router in the future so I wired up everything with plugs so I can move this control box from one machine to another. I just need to get one more stepper drive for the forth axis.

Next step is to wire up all the motors and try this out. Then I need to take apart the mill and install the new ball screws and motors.

It's been a slow process, but hopefully I will have this up and running soon.

Dale P.

 

[DICKEYBIRD]

Nice job Dale! Clean & well laid out, I like it. Like my ol' buddy Bob Stewart (rest his soul) used to say: "If it looks right, it IS right!"

Got a link to where you sourced those plugs & sockets?

 

[ibuildstuff4u]

The plugs are Speakon jacks and are used for Pro Audio speakers. The smaller ones have four connectors and are to connect the stepper motors. The larger one has eight connectors and is used to input the limit switches and E stop. The jacks can handle 20 amps and are a lot nicer than the cheap mike jacks that some systems use. The best source for them is Parts Express. Just go to their sight and search for speakon jacks.

I fired up the system last night and so far everything is working good. The motors are so quiet I didn't think they were working at first! I really like the digital drives, they are much more quieter than regular ones.

Dale P.