Build Thread- Upgrading an old (1993) Minitech Mini-Mill 2.

[jalessi]

Hey Cat,

Are you using them for home switches or just as limits?

If you home the machine after cutting a wax and then rerun part of the job how does it look?

They must be very good with repeatability if you cant see any flaws.

Since at times you use a .003 cutter that would be awesome!

Jeff...

[Fixittt]

I use them for home switches. and have never seen any variations in flips ect.

[LegendCJS]

Its been a while since I've posted, but a lot has happened with the mill. The power supply and driver package from Minitech has been installed and works beautifully. We took the old driver board and steppers off the mill and can use them in some other less demanding motion control task that may come up in the lab.

The EMC2 software has been configured to work with the new steppers. The mill has 10 tpi led screws and I'm running the drivers at 1/8th micro-stepping for a jog speed of 1 inch per second. At this jog speed I can brace my hand against the X or Y stage and the steppers will move the entire mill in the opposite direction instead of stall out. And the Z-axis now moves smoothly on command. Previously it had been moving with a pattern of a rapid series of bind and slip sounds on the vertical rails.

We initially had some latency problems on the PC driving the mill. The System Maintenance Interrupt was causing a 290+ us latency every 20 seconds or so (as reported by the RTAI (or RATI, can't remember) latency tester) but we got a computer wizz in our lab to disable that. Now the worst latency reported is about 15 us- well within the EMC2 guide's recommended 10-20 us latency range for software micro-stepping.

The other big development besides the massively increased strength of the mill is that we found all the old tooling and documentation! So that is plus 3 additional collets (previously the mill had been stored since 1993 with only the 3/16th collets in the spindle) a drill bit chuck for the mill, and a half inch end mill holder the screws onto the threaded end of the spindle. The old box of tooling also had a lot of stair blocks and things for work holding and other odds and ends. There was also a pyrex glass tub of what feels and looks like 15+ pounds of woods metal or something similar- no ideas with what to do with that yet. Anyone have any good CNC use ideas or Woods' Metal? And there are a bunch of manuals for the mill. Hopefully they won't tell me that the grease and oil choices I made for the screws and rails are bad for the mill.... The last thing in the box was some old old software, I thin they were on 5 inch floppies... I'm glad that machine tool hardware doesn't get outdated lke computer hardware.

I bought some rubber sheeting to make way covers out of, and I need to mount the magnetic home switches. I'm glad that Fixittt posted pictures of his mounts, that will be helpful.

Pictures to follow in a later post, including details of switch mounts and way covers. Ultimately I want to put this thing on a standalone rolling cabinet type thing that hold the driver computer, 15 inch flat screen monitor, keyboard, mouse, the Minitech mill, a drawer for all the tooling, and the driver box. I need to shop for one of those platforms that has wheels that retract up via foot peddle or lever to let it stand on sturdy legs after transport.