.png)
Tweet
Bought a Bridgeport Boss Series 1 CNC. Hardware good, electronics bad. Am looking at converting to Mach3/Mach4 (I have experience with Mach3) and an Ethernet Smooth Stepper. Don't have it in hand yet, but am going to scout it out this weekend. I have 3 stepper to servo boards that I got some years back, i believe they were developed by a guy in Australia, and if the drives are okay I will give them a try. My other option is some servo drives from CNC4PC- looking at the DG4S-16035 or DG4S-08020. will have to get the motor details. If I got for ESS I will probably use the C25 Ess breakout board like I currently use with my KX3 CNC.
-
-
My direct experience is with Centroid and the Acorn, playing with a DMM Servo right now -
OEM bridgeport servo motors are quite high voltage. I have done a few retrofits on bridgeport boss mills. I forget exactly but somewhere around 140V as I recall which eliminates a lot of servo drives from consideration, especially using mach3/4. The currents required are fairly large also. They are quite substantial motors.Originally posted by kf2qd View Post
Comment
-
the servos that are on the machine are certainly the least expensive way to go forward. It depends on how much you want to spend..
You go as far as re-using the existing servo amps if they still work. (using your step -> analog boards) I have never used these - I assume they are something like this
If it were me - I would certainly go that route - reusing as much as I could. If one of the existing drives went bad - replacing it with another analog drive isn't a big deal (Like AMC or such)
sam
Comment
-
It's an adventure. You will learn a lot. One of the things I learned was often my cleverer idea wasn't.Last edited by Bob La Londe; 05-20-2023, 08:39 PM.--
Bob La Londe
Professional Hack, Hobbyist, Wannabe, Shade Tree, Button Pushing, Not a "Real" machinist​
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.Comment
-
Well, I got the machine inside my shop. Had to disassemble the spindle drive and remove the spindle, fortunately it come apart in manageable sized pieces. The table had to come off also, but I was able to make use of a Harbor Freight motorcycle lift with an 18" high stand built on the top of it so I could get the table up to the minimum height of the knee. Pushed it up the slight incline into the shop using a couple 2x4s and my Jeep in 4 low. 6 inches at a time and no supprises. I like it when moving machines is boring...
Today I got the drive/computer cabinet hung and I need to rewire the interconnects between that and the power cabinet. Then I will see if the CNC will cooperate. Wish I could get hold of the info on the software in the machine, I think the Motorola 68000 has more than enough capability, but the existing software has a few details that are missing. Like work piece coordinates.
The iron on this machine it beautiful. A few scratches added to the tops of the cabinet, but the machine really looks lightly used. Serial 389 from week 45 of 1985.
I am still planning on converting to Mach and ESS but to do that I will need to sell my KX3 to have the cash.Comment
-
Got everything all back together and put some power to it. No bangs, no sparks,BUT... It goes through the computer checks and will let me run a keyboard test, 2 keys, the decimal point and the EXECUTE key don't work, but I knew that. The error light comes on and flashes off briefly when the button is pressed. It tries to enable the drives, but I think the error is keeping that from happening. And the error may be some glitch in the code. I have the right half of the screen displayed twice after all the system checks are complete. I briefly see part of a message with Bridgeport in it and then the screen messes up.
I bought it with the understanding that the computer was having issues and am intending to convert over to Mach, so nothing lost, nothing gained. I now need to see if I can enable the drives and have them behave. If they won't behave i guess it is 12V on the motor leads and the check the tach lines from the motors to see if they are behaving. I can get new servo drives with a Step/Direction control and that may just be the way I go.
The mechanical parts of the machine check out really nice. Another machine where I probably did more damage to the paint getting in the shop than the previous owners did.
Now to save the money for the next step...Comment
-
In my opinion Mach is far easier with pretty much all interface based setup, but after having run a LinuxCNC (PathPilot) based control for 6 years now I might actually consider it instead for my next build. I do not need a super fancy interface. Just to understand it and trust it. I've even considered hacking PathPilot since it is a pretty nice interface.
I've been watching a series on YouTube about setting up LinuxCNC for the first time, and I'm bored. I'm upto episode 8 and so far we haven't done much more than run a latency test. Geez. I've done that much already more than once. LOL.--
Bob La Londe
Professional Hack, Hobbyist, Wannabe, Shade Tree, Button Pushing, Not a "Real" machinist​
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.Comment
-
I will never touch another piece of software from that guy. Centroid is very nice, want to try Linux CNC next.Comment
-
Well, Bridgeport did something interesting with the servo drives on the Boss 9. From the drawing is appears that the tach feedback from the motors goes back to the computer instead of the servo amp. So any adjustment to compensate for the servo amp being out of adjustment is made in the computer rather than the servo drive. Hadn't seen this before. Other DC servos I have worked on had the tach feedback into the servo drive and the computer just gave an analog signal that could be adjusted for a zero offset. And when I took time to adjust the drives every so often I would adjust the drives back to zero offset voltage. I guess Bridgeport was trying to make a drive where the settings in the machine could stay hidden, and never be adjusted by a user..
I have been going through the drawings and chasing down the details of how the drives are connected, think I have the analog inputs to the drives figured out. Now to go through another drawing and figure out some more details...Comment
-
That's a true closed loop operation. As far as I know Mach 3 can't manage that. Don't know about 4. LinuxCNC is supposed to be able to close the loop to the computer, but you will know need some help... Not from me.--
Bob La Londe
Professional Hack, Hobbyist, Wannabe, Shade Tree, Button Pushing, Not a "Real" machinist​
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.Comment
-
When you say 'tack feedback' are you really talking about the encoders?Originally posted by kf2qd View PostComment
-
what are the 'stepper to servo' boards you have?Comment
-
Tach Feedback. Typical DC serv motors have 2 parts. The Armature - which is where the work is done, and the Tach - or as it used to be called - the tacho-generator. The tach is actually a generator that will produce - at low amperage - a voltage of, i have seen from 7 to 10 volts per thousand RPM. this would typically be fed back into the servo drive into the amplifier section and would help compensate for torque or load on the motor and cause the amp to drive the motor more or less depending on how the motor speed was compared to the analog input to the drive amp. By adjusting the tach gain the motor could be made to produce more torque when it was loaded down. There was also the gain adjustment on the analog input, and if someone didn't pay attention to which one they were adjusting it could really make a drive behave poorly. This was back in the day when servo tuning was done with a small screwdriver, which every technician had in his pocket liner, along with a small hex diddle stick and a pen or 2 to fill out reports... Don't know how many of those little screwdrivers I have lost/misplaced over the years. Used to get a few every year from the various vendors.,,
And then there are encoders that are attached to the motors, but they give qudrature feed back to the computer so it can keep track of where the axis are.Comment
-
The small boards I am talking about are some Rutex 997A Stepper to Analog Servo Boards. They have inputs for the step and direction signals, a couple for the A & B phases from the encoder and the +5V and common for encoder power, and an analog output to the servo drive. I believe it takes a supply voltage of 24VDC. It has a PIC16C711 on board, at the very least it has a counter with 2 inputs, one input driven by the step and direction inputs, and one driven by the encoder. And it uses the value in the counter to then control the analog output. If the counter has a positive value, the the output is a positive voltage, and if the counter is negative the the analog output is negative. as long as the servo drive can respond fast enough the counter value does not overflow and the servo behave a lot like a stepper, but with more speed potential.
I don't think it would be to hard to make one up using something like an Arduino (an ATTiny2313A that i sed fro a stepper driver), it would just be messy because the Arduino only has positive analog outputs. A similar type device with a plus and minus 10 volt output would make it simple...
Comment
Comment