CNC Bridgeport with Heidenhein control

I need to do a lot of reading about CNC in short order so that I can understand all the terminology, such as double loop, etc.

If anyone can suggest an intro book into this, I would greatly appreciate and buy it immediately.

Here's a guy who converted the same exact mill to EMC2

The repair mostly will take good schematic diagrams and good troubleshooting information in the manuals, and good test equipment (logic probes, oscilloscopes, and other such things.)

As for fitting a newer control -- look into the EMC package running on a modified linux kernel with a real-time sub-kernel which runs the normal kernel as one task. The software is free. It runs on boxen which used to be Windows boxen. If the mill in question has servo motors instead of stepper motors, you will probably need something like the Servo-2-Go board (which can handle eight axes at need. Three for X, Y, and Z, another for spindle speed, and two more for something like a two rotary tables at right angles to each other. :-)

Well ... my Bridgeport Series I (BOSS-3) CNC mill has the X-axis leadscrew (ball screw) locked stationary, and the nut is rotated around it in the saddle. This suggests that there is no practical way to fit handwheels to the existing leadscrews. The Y-axis one does rotate, but there is no exposed way to rotate it unless you take the cover off the belt guard and fit a handwheel.

I don't know the Series II -- other than that it is larger. And the Heidenhein controller is newer than what my Series-I came with, which was a Bridgeport home brewed one built around a LSI-11 CPU and some custom wire wrap boards (which were later replaced with printed circuit boards).

The price sounds good, if you can move it and have room for it, and with your familiarity with linux, the EMC package is probably the way to go.

Good Luck, DoN.

If that is all that is wrong -- that should be easy to fix.

Good Luck, DoN.

Focus was unusually poor for your work.

Looks like servo motors, based on the one to the left of the head, so if it is more than just the monitor, you may want to go with the EMC package based on linux.

Tooling looks nice -- including a sacrifical tooling plate to protect the table.

Enjoy, DoN.

The major cost here will be your time. A lot to learn. My pure guess would be about two man months. The more equipment you can reuse the more you save and the more time you'll spend. Its easier to do a simple machine first, this one isn't it. Look in to how you do the servo drives with the Heidenhein scales and what all you'll need to interface all the I/O to your Linux box. These will be the two largest costs.

You'll end up with a machine you control from a computer keyboard - fine for hobby work. Most of my experience is with refitting a machine so its a professional job that is better than new. Costs easily run 15K to do this.

Karl

Did it not come with a controller, Iggy?

You remember when you made printouts of coordinates and then turned the handles to those positions to make shapes? That is what CNC control does, but it will do it on all 3 motors at around 1000 times per second depending on controls. The double loop, for example, is when the control gets a feedback from the motor and also gets feedback from the scales on the axis. The motor feedback is used to sense what the motor is doing, the linear scales sense the actual table position. These could be the same but if your ball screws get a tiny amount of backlash, the motor will try to make up for it.

The servo motor gets power to run forward or backward and has something to sense turning so it can be controlled, usually through a Proportional, Integral, Derivative (PID) control loop.

My system uses motor feedback to the motor amplifiers and uses encoder or scale feedback to the CNC control. So, if my position is off a move is required, my control will send out a signal to tell the drive to move the motor at a speed and direction. The amp will send power to the motor and sense the motors movement, as the position error is smaller, the controller sends a smaller signal until the motor stops at the correct position.

RogerN

Looks like a center drill to me..

Load up and run EMC2 or Mach3 in demo mode with no machine. I use Mach3, mostly because it was ready for prime time before EMC2 was. When I started with CNC I tried EMC (EMC2 wasn't out then) and Mach3 side by side on identical PCs controlling the same machine (at different times) and chose Mach3 as the more polished solution. EMC2 should be more on par with Mach3, but I haven't tried it since I already have Mach3 and the hobby license is unlimited.

CNC controls are a *lot* simpler than you might think, and a little fiddling and you should have it figured out very quickly. The G code that CNC controllers operate on is nothing more than simple positioning commands for the most part. Where is gets complicated is in the CAD/CAM end and generating code for full 3D work, and you really don't need to get fully into that for hobby work. Most hobby work tends to be 2.5D, not full 3D and that makes it quite a bit simpler. Look at SheetCAM for an example of a decent 2.5D CAM package.

For hobby work, you'll find that the few things you really need 3D moves for are usually ones that are easy enough to hand code. There are specific G code commands for arcs and stuff which are useful if you're hand coding, but they aren't typically used by CAM programs which mostly generate the code as line segments since code length isn't a concern on an modern CNC control.

I have not brought it home yet, but it does come with a controller and, if I am to believe the seller, the only thing wrong is the display that has a bad transformer (which is something weird and cannot be replaced).

OK, I think that I understand that. I will look for some webpage that described architecture of a CNC system. I already have all the manuals in my possession.

Thank you Pete. Are there some provisions for using this mill in kind of manual mode. Let's say that I just want to drill a hole in a part and mill off a corner, something that is easy to do with a manual mill. How much harder would it be to do with CNC. Maybe with keyboard arrows or some such. The question probably shows my ignorance, but I want to know how much I am giving up by switching to CNC.

So, Karl, what would you (with your skills and all) do with this bridgeport, would you just try to restore its Interact 2 controls?

Two "manual" functions:

MDI - Manual data input, basically a CLI interface to the G code interpreter. You just enter a single G code command at a time like "G01 X4.5 Y3.7 F150" which moves to the specified X and Y position at the specified 150 IPM feed rate.

Jog wheel - You can manually move one axis at a time using the jog wheel and you can set the jog steps to increments like 1", .1", .01", .001".

Once you get familiar with G code, jog will only be used for "touch off" functions to establish your zero, and then you'll use MDI input for anything manual, or just pop up a text editor and write a quick chuck of G code then load and run it.

I haven't looked at the EMC2 docs, but I know there is a decent G code reference section in the Mach3 docs you could download and look at. G code is a standard, so it's pretty much the same for any control (they do have custom extensions on some).

My recommendation would be to use the existing controls if it's a simple thing like replacing a monitor. Then investigate those controls to see if the servo drives and encoders would be reusable and plan the EMC2 or Mach3 retrofit while you use the current controls. When the current controls finally die and can't be repaired you'll be ready for the retrofit.

Mach 3 has "Wizards" included in the licensed version that will allow you to simple code very quickly for mill drilling, pocketing and surfacing.

If you're looking to make some money:

I'd part the machine out. The servos, scales, and head - sold separately - will bring you about a 4:1 return.

If you want a CNC machine:

I'd spend a short fixed amount of time, say 2 days tops, trying to make the old control run. It it works, great, but it won't last long. Either way, start learning EMC2, you're used to linux so its your best bet.

Iggy, you're in the heart of a dying industrial machine town. You can find a professional working CNC machine real cheap. IMHO, spend maybe 5K and get a real CNC machine. Have Gunner tell you what to get.

Karl

I don't think Iggy has the space or desire for a full VMC for hobby stuff. Even a small nice machine like a Mycenter 1 is pretty big compared to the Bridgeport.

None of the full CNC machines will fit. If my spouse sees me bring one in, I may have to sleep inside of those machines.

The Series II Bridgeport will fit, with some adjustments, such as getting rid of some of my stuff for sale.

If I can get it to work, and if I can use it for small hobby projects that one normally does with a manual mill (like drill three holes and round two corners), as well as for CNC projects, I will be very happy and it will be a useful upgrade over my existing Bridgeport.