[Newbie] I bought a Haas Mini Mill basket case

M

Mjohnson

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Hi everyone. I just bought a 2005 Mini Mill. It has had all the controls stripped from it. The mechanical condition looks good.

My intended use is as a hobby mill making gun and airgun one-off parts, so speed is not a concern. It has the axis and spindle motors intact, but no electrical controls for them. I had planned to do a very simple Centroid Acorn conversion and use stepper motors on the axis, and a 3 hp induction motor on the spindle. Then sell off the stock motors. But, if there are non-Haas drives that can drive them, I might just reuse the stock motors.

So, does anyone know if the spindle can be driven using a common VFD?

Also, are there any commonly available servo drives that could work with my stock axis motors and use step and direction signals from the Acorn control?

Thanks!

Mike

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Congratulations on your new project. :)

First, putting steppers on that machine would be like putting a Yugo engine in a Farriai. I think the original servo motors are Yaskawa, so Sigma II drives for them should be readily available. You need to take a look at the data tags to get the model numbers so you can get a matching drive. Trying to mix brands of servo motors and drives would be more trouble than it's worth. A good alternative would be servo motors and drives from DMM Technologies https://store.dmm-tech.com/collections/types?q=AC Servo Drive

Also take a look at the data tag on the spindle motor to see what it is. If it's a standard(ish) 3 phase induction motor then it can be run with a VFD, but if it is a PM servo motor then the mating drive is going to be required. As I recall most of the mini's have around 15HP spindles, so that might be a bit much for the available power in a home shop, assuming you have an average home shop. Nothing wrong with replacing the spindle motor with one with a bit less power to meet your needs. If you decide to replace the spindle motor, I would take a look at the Automation Direct Black Max line. https://www.automationdirect.com/ad..._s=("Marathon Black MAX" "Marathon MAX Plus")

And their GS3 VFD line

General Purpose | Drives & Soft Starters | Products | AutomationDirect

General Purpose from AutomationDirect, the best value in industrial automation - low prices, fast shipping, and free award-winning service.
www.automationdirect.com
 
All the older minimill data I could find indicates it has a 5hp (or 7.5hp) induction motor spindle and uses a VFD. Spindle orientation is - I think - accomplished with a shot pin while the VFD jogs the motor slowly. Not a C-axis.

Jim's suggestion about a GS3 VFD is a good place to start. Here's a link to the HAAS spindle troubleshooting guide and is a good jumping off point for researching how to spin the thing.

https://www.haascnc.com/service/tro...--how-it-works-and-troubleshooting-guide.html

Since you're going with Centroid , they'd be the best resource on the drives and spindle. Get in touch with them and let them know what you have. It may make more sense to sell your Yaskawa servos and go with another brand - but be aware that not all servos have standard shaft sizes and frame sizes.

Suggest you get the dataplates off the servos & spindle motor. You can then talk to Centroid or do your own research and find out what frame size, kW, and shaft size the axis motors are.

Repowering everything with new drives may also give you an opportunity to switch everything to single-phase operation. Would make the mill MUCH more desirable if you decide to sell it. On the other hand, a rotary converter is probably less expensive than a 5hp+ single-phase VFD.
 
I know what you mean about the Yugo and Ferrari. Since I already have a good stepper system, I may try that first. It's just a hobby thing.
I've looked at DMM servos. That route would cost about $1800.
I'm also looking at Centroid Oak using the original servos. That would cost about $3200.
I just really like the simplicity of steppers.
I read the Tormach white paper on their stepper system and design philosophy of the model 1100. It made a lot of sense to me, since I only do one-off prototype projects.
The biggest issue is the lack of the spindle drive. The motor is 7.5 hp, and the original vector drive was a 20hp. I've read about others brand drives like Automation Direct, and their vector drives on single phase power would need to be 20hp too. That is just cost prohibitive.
So if I downsize the spindle drive to 2 to 3 hp, then there isn't a lot of need for high feedrate servos. 2-3 hp seems to do well on 220v single phase power, and the price is right.
My first hurdle comes Saturday when it gets delivered. The head is in the up position,it needs to be all the way down to make it through the garage door, and there is no way to jog it down because the controls are gone. Its being held by the brake on the Z axis servo.
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Well since you have the steppers already, you may as well use them. You can always change them out later if you want to.

As far as the spindle motor, you need to take a look at the data tag on the motor then start thinking about a spindle VFD. You can get one for about $400 that will work on single phase, but the motor data tag is important before even looking. As you say, a 3 HP motor would work too but it might be cheaper just to run it with the existing motor.

It might be possible to just overcome the brake with a ratchet & socket on the top nut (if it has one). I was able to do exactly that with the X brake on my lathe to move the axis. I don't think the brakes hold all that well. Or most of the brakes are 24VDC so just powering it up would be possible.
 
Well, I have completed the Acorn retrofit to my mini mill. I had a few unexpected problems. The spindle motor required a rebuild with new bearings, and the Z axis linear bearing trucks had to be replaced. Other than that, the upgrade went really well. I used my nema 34 and 42 steppers with Leadshine AM882 drives. I get 200 ipm rapids and I'm happy with that. The tool changer is missing a lot of parts, and I don't machine unattended, so I'm not sure if or when I will tackle that project. For now, I will hand load tools. It was a great project.20200329_191417.jpg20200329_181836.jpg20200229_153004.jpg20200229_131447.jpg20200227_200335.jpg20200226_203449.jpg20200225_212705.jpg
 
Man, that thing looks like it had a rough life. Good job bringing it back from the dead. What did you pay for the mill?
 
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