Blomberg B-Trucks
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CNC Lathe
CNC Mill
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CNC Mill

Mill scrap.jpg



   During the CNC Lathe build it was clear that I would have to build a CNC Mill to go along with it. I had planned to buy a new mill and convert it much the same as I did the Lathe. Since I had spent a little more than I intended to on the lathe I was in a hold pattern until funds were available. All holds were released when this "gem" arrived at the scrap yard, an old Sharp CNC mill. Even though the control system was junk it is a great start on the project. The machine is in very good condition, the ball screws are tight the ways are clean, and it is rock solid! Interestingly, it seems to be one of a kind, I called Sharp for some parts and said they could not identify it. My take on it is that is some kind of freak lovechild between Sharp and Dah-lih. anyway it will make a nice conversion. I have just ordered new DC drives with the intent on reusing the DC servos, It will save a ton of money even though I loath DC motors... one of the few times I have cheaped out. we'll see if I regret it.

                                        I have been accused of photoshoping this picture! Well, its real... True story!




Squeeze Play

Mill in shop.jpg



   In another page I mention how my shop is not big, well nothings changed there... I am still making it work but I am really getting squeezed!

   Anyway,  Since I brought the mill "Mel" home I have done quite a bit of work. I started with a little spruce up in the head. I had to remove the motor and belt head just to get it in the door, and in the process learned that there was an issue with the range selector. That was when I learned it was a one of a kind and was dificult to get parts for but with the help of a couple of great guys at Sharp I got what I needed and re assembled the head. I spend a week or two getting the machine cleaned up (if you ony knew what was in the coolant tank... Disgusting! ) .

   After doing some experimenting with a DC servo drive I was ready to start designing new controls. I bought a new control cabinet (and cut it down to the size I needed), bought a pile of new parts and off we go...

PHOTO: This was taken 9-4-13 mabee 2 months into the build. progress has been slow, funding and other projects keep jumping out.

Servo Encoder

Mill servo.jpg



   Part of the challenge with reusing the origional motors was that they had resolver feedback, and any modern drive uses an encoder. I calculated the Pulse/Rev I needed and got the best physical fit available, I did need to make an adapter plate though. In testing it performed very well. 





Finally! Progress!

Mill Panel.jpg


  Here is the assembled cabinet ready for wire, it hold some real goodies! On the door is the PC, it is a mini ITX chassis that is smaller than most modems. the top row in the cabinet holds a terminal strip/relays, and the Ethernet motion controller. below that the Main fuse, selector contactors for the "W" axis or coolant pump, and the Servo drives with their brake resistors mounted to the cabinet side. then underneath the Main contactor followed by2 VFD's the smaller for coolant/Waxis and the big mother for the spindle motor. Next Down, the power supply I built (20 amp 100VDC) and a 24VDC control power supply. It is a little tight in there but the door mounted fan will keep it all cool.



Last Lap!



     The spindle and power drawbar threw out a couple last minuite kinks: I mentioned previously that the range selector had been cobbed up at some point in its previous life, well I discovered "patient one" of that cobbling pandemic. As all power units put a hurting on the drawbar, at some point this drawbar had been replaced. As I have learned, parts for this machine are like unicorn horns, they can be difficult to source; this drawbar is likely a bridgeport part and therefor almost worked, but it did not fit down through the spindle splines and probably sealed the fate of the machine. When the Z-axis extended all the way down it took the lower coupling down with it knocking it out of gear and breaking the range selector shaft. Luckily I hadn't pinned the shaft to the handle yet so it slipped when I did this instead of breaking. I modified the drawbar to correct this issue and all is well.

"Rat Wired" I think not..



 This is the photo of the finished panel, pretty clean. It's cramped for space but ventalated well.






Coming down the final stretch, the build is nearly complete. I have just a few details to wrap up at this point. The system works great, the Elo touch screen, minicomputer, Servo drives, and Ethernet smooth stepper... all working harmoniously together with more blinking lights than a control station on the Starship Enterprise. It has been a fun build but I am anxious to start using it. I will need to make a few fixtures for my product lines, that will certainly take some time but I have a few side jobs to help familiarize myself with the machine before I begin that.

What’s next?  Stay tuned…

Final build notes:

Overall,  I LOVE this machine; it really fit my needs for size and budget. It doesn't have all the features I want but it is light years beyond the expectations I started the year with. What would I do differently? Not much...I do not cut corners on a build. I would have liked more cabinet space but that was a requirement of my limited floor space so not really negotiable.

Link to video on youtube: http://youtu.be/FAXkIG0l0eE



Smoke and Fire

   I've made it look quick and easy, haven't I? Truth be told it is (if you have patience), I have had plenty of trouble along the way. This project has been riddled with component failures and setbacks. Buying the machine from the junk pile I knew it would or could have some major defects that I would find, and did with the range selector and draw bar. Arranging transportation was no walk in the park; it weighs in at 3600lbs! The touch screen (which I bought used) had trouble connecting to the Pc, finally talking to Elo tech (great help, thanks!), I found it to be defective but covered under warranty. The pc decided to change video drivers out of the blue one day and led me down a bumpy road. I took it to a friend who loaded windows onto the machine for me and he mistakenly powered the wrong plug on the PC (I added an output plug for relay latching) which smoked the power supply in the PC, he took care of that, but it was a setback none the less. The machine DC power supply has been the biggest pain so far, first power up was fine it made 117Vdc first try, on the second power up- fire shot out of the panel! After a little snooping I found the rectifier had failed (a $20 high current rated premium part) I replaced it with the next step up ($40) and it shot fire twice as far... not the desired outcome... So maybe I skipped a step, I apparently had a current draw issue. I traced it down to the Servo braking modules ($30) for the servo drives, two of them had failed to very low resistance deciding that only one was really needed anyway I reconfigured and this time I ordered cheap $5 rectifiers just in case. It was now up and running. I tuned the servos, drove the axis' around and was happy, then the x-axis encoder failed, another $175 up in smoke... F-WORD- I yelled ... That may be covered under warranty I have yet to see. Well with all that out of the way I've powered it up a few times it tests well, I did the final touch ups in the panel added the wire covers and a little tidy up. I turned the machine on again....and nothing both main fuses blown. F-WORD- I yelled a bit louder than last time. This time I traced it down to the toroidal transformer. It  is now resolved, but it required several calls to Hammond (To whom I give great credit for their excellent tech help.) It turns out these transformers have an exceptionally large inrush current that no fuse can handle. They recommended a NTC resistor to damp the inrush. In the meantime I replaced the fuse holder with a breaker because fuses are more expensive. It has not tripped, even though I havenot yet added the NTC resistor.

On to making chips!