Something different - CNC milling machine build

[halfspec]

No more printed parts on this project (yet)

Boo! Unsubscribed

No worries, I'm still down for the read. I was just going to be extra interested if there was more 3d printed part design as that's a field I'm moving into myself 

So I had to repeat this process for each motor.  That seems simple but it really took about 8 hours, it's a lot of trial and error.

I feel you on this one. Manual PID tuning is no joke. Autotuners are only good if the loop is 'kinda-already-under-control.' Tuning it manually is only sorta fun if you've got really good feedback and you're moving towards a controlled loop, but it still takes time.

Good stuff
Lane

[Dvous]

No more printed parts on this project (yet)

Boo! Unsubscribed

No worries, I'm still down for the read. I was just going to be extra interested if there was more 3d printed part design as that's a field I'm moving into myself 

So I had to repeat this process for each motor.  That seems simple but it really took about 8 hours, it's a lot of trial and error.

I feel you on this one. Manual PID tuning is no joke. Autotuners are only good if the loop is 'kinda-already-under-control.' Tuning it manually is only sorta fun if you've got really good feedback and you're moving towards a controlled loop, but it still takes time.

Good stuff
Lane

I'll see what I can track down for pics of other things i've 3d printed, ill PM you if I find some of the more interesting things i've done.

Manual mode would be important for me as the only way I could fit this in my garage is if it replaced my full size drill press.  Also cranking by hand, or even using an autofeed, I can more easily judge on the fly whether I want to speed up or slow down the feed rate based on the chips and noise it's making.

Fair enough, In that case here are a few options:

1) conversions for an existing manual BP that retain manual function:
- http://www.microkinetics.com/index.php?page=conv_kits/floor_model
- http://www.elrodmachine.com/ (these are very popular and high quality kits)
- http://www.flashcutcnc.com/retrofit-solutions/bridge-port-kits

2) buy an existing CNC machine that retains manual control:
- Mitutoyo Millstar Conversion (like mine)
- Bridgeport series I CNC (not boss machine)
- Some Prototrak machines (though, many are only X-Y controlled)
- EZtrak systems (again, many are only X-Y control)
- Anilam CNC converted machine (basically the same as mine)

I would STRONGLY recommend you buy an existing CNC with a bad controller or other bad parts...the ballscrew conversion and buying all the hardware is very expensive.  Plus that way you get commercial quality motors and drive hardware and not some chinese crap.

[Dvous]

Time for an update:

So once I was happy with the motor PID tuning I had no more reason to have the motors off the machine (again, DO NOT tune the motors on the machine).  So I put the motors back and on and started back on the control enclosure.  To start with I removed all the old connectors and started thinking about how best to adapt the Ethernet bulkheads.  Finally I decided to just make a new panel, that process went as follows:

These are the abandoned openings from the old connectors for encoders/limits/controller
[attachimg=1]

So I just hacked that out with an angle grinder (obviously I removed all the new stuff first lol)
[attachimg=2]

Next I cut an aluminum plate off some scrap I had and started mocking up the bulkheads
[attachimg=3]
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So once I was happy with the layout I fixtured it up on the mill and bored some 1" holes in it
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Lastly I drilled 4 mounting holes, installed the bulkheads, screwed it back into the enclosure, and labelled the bulkheads.
[attachimg=8]

[Dvous]

So once the box was setup to work with the ethernet cables I started putting all the components back in for the last time, Including mounting the ESS and C62 boards properly with nylon spacers off the side of the box.
[attachimg=1]

And Started wiring everything up correctly, you might notice that the 3 braking boards are not connected...more on that later.
[attachimg=2]

And finally I could bring everything outside and set it up on a cart hooked up to the machine.  As of this point the machine would move in Jog modes only due to the lack of limit switches, but it moved none the less.
[attachimg=3]

[Dvous]

Another of the machine put back together (I took the cover off the Z-axis mechanism for a reason ill mention later).
[attachimg=3]

Once the motors are installed back on the machine and you hook up your controls the first thing you really need to do is tune the Mach4 end of your motor control.  This primarily consists of calculating you Count/unit value which is the amount of steps your encoder will count per unit distance.  My controller is setup for inches so that means how many steps go by per inch of travel.  This is a product of your steps/rev setting I mentioned before, your gear reduction ratio in the belt drive units, and the pitch of the ball screws.  You enter that in the motor tuning tab under configuration>mach in Mach4.  Your curve should be a trapezoid as shown here:
[attachimg=1]

You can see in that pic Mach will automatically calculate your rapid traverse speed as well (mine is about 220 Inches per minute, which is excellent for a machine like this).  Once you have this sorted out you'd be best off to check your results.  The easiest way to do this is put an indicator on the spindle in the direction you want to test and zero it, command the desired axis to jog a specified amount (.001 for example) and confirm you see an equivalent movement on your indicator.  That setup is shown in the following pic, I was testing the x-axis travel.
[attachimg=2]

Also you need to test the movement over longer distances.  I don't have pics but I tested down to .0005 movement with a dial indicator, and up to .900 with a drop indicator in every direction.  Once I was happy with that I moved it 8" in the X-axis, and 8" back into the indicator.  If it still hits zero after that much movement then your good to go.  I made that movement via the following very simple line of code.
[attachimg=4]

Also, that was the first line of code that this machine has run for me, good times!

EDIT: the reason the z-axis is partially ripped apart in that first pic is because I was having trouble dialing in the z-axis movement, and actually I'm still having an issue.  Somewhere i'm loosing .005", I hesitate to call it backlash, Because the ball screw setup alone has no measurable backlash.  The difference occurs between the ball nut and the bracket that attaches it to the spindle.  At first I had like .030" play which is ridiculous, I pulled it apart and found the bolt that attaches to the spindle ram was loose.  After tightening that I still had .005 play.  I know you can compensate within the program for backlash so I should be able to work around this but really it shouldn't exist at all.  Fortunately it's only in the Z-axis so it'll only effect my depth's.  The X has ZERO backlash, and I really mean nothing.  And the Y-axis has about .0005" backlash, which is no problem.

[Dvous]

So I also got my limit switch setup in the mail the other day so I started messing with that.  Once again CNC4PC makes it shockingly foolproof by wiring everything to an ethernet connector.  And since the C62 board is made by them too, and I run Mach4 with installer settings provided by them I literally just plugged them in and they work...literally that simple.  I needed these plugged in for Mach4 to actually run lines of code, so at this point I just wrote some basic lines to move the table around and measure relative movement.

Pics of the switches:
[attachimg=1]

And it plugs into the board here:
[attachimg=2]

So I've been thinking for a while about how I want to mount these.  I knew I wanted them enclosed to protect them from oil/chips (and eventually coolant).  So I came up with these little aluminum switch "pods" if you will.  I started on the X-axis first.

First I cut some 3.5" sections of 1"x1" aluminum tube:
[attachimg=3]

And used the BP to mill a slot in each:
[attachimg=4]
[attachimg=7]
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Next I mocked up the switch and drilled a couple mounting holes:
[attachimg=6]

Then I started looking at mounting.  I figured at first I'd use T-slot nuts but didn't have any for this particular size.  So I snagged some nuts, tightened them onto a bolt and thought about ways to precisely cut them to size...how should I...ohhhh wait, the bridgeport sitting in front me
[attachimg=8]
[attachimg=9]

[Dvous]

Next I pulled out ye olde mig welder and welded some washers to the back of those nuts:
[attachimg=1]

And in case anybody is still in the dark as far as where i'm headed with these:
[attachimg=2]

A couple mounting holes later and I wound up with this:
[attachimg=3]
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So now that I had a viable switch mount for the X-axis I had to make a "striker" for the switch to hit and activate.  All BP's have these two threaded holes in the front side of the table for only god knows what to mount to.  So I cut a 5" piece of the same aluminum tube and bolted it in...the studs are temporary, its all I had handy in that thread.
[attachimg=6]
[attachimg=7]

And much to my surprise with no more work on the striker piece it actually activates the switch, I'll add a piece later to create a more positive activation but nonetheless it does work:
[attachimg=8]
[attachimg=9]


And that's were I'm at for now.  I need to fabricate limit switch mounts for the Y and Z axis, setup the limit/homing parameters in mach4, sort out the Z-axis .005" discrepancy, mount the control box/computer/monitor/keyboard/mouse, build a small switch panel to run this thing (e-stop, on/off, etc), straighten out all the wiring, setup the control pendant.  Then its on to the next few stages, but i'll have a running machine at that point.

[Dvous]

I've been really busy at work lately and got sick this past weekend so progress has been slow on this.  I did manage to mount the Z+ limit/home switch though:
[attachimg=1]
[attachimg=2]
[attachimg=3]

And also got the parts to put together my panel which includes: E-stop button, On/Off for VFD (spindle), On/Off for controller, USB panel mount for thumb drive for programs, USB panel mount for pendant to plug into, Extension cable so I can mount the VFD control panel remotely and put the VFD in a box.
[attachimg=4]

[Dvous]

Haven't updated this in a while.  The machine is now up and running, I finished the limit switch setup, built a redneck computer swing mount, and dialed in the programming side of the equation...It's pretty much been making chips non stop since the second I got it running right.  I've built a couple car related items, a couple gun related items, and one artsy project that is just a great evaluation of the machine capabilities...I'll updated with pics and more info soon.

I also wrote an 18 or so page instruction manual on how this could be replicated and why I did things the way I did, I'll attach that here as well for those interested.

[freeskier7791]

Cool!  Did you make one of those cube ball thingys?

Sent from my SM-G920V using Tapatalk

[digitalsolo]

Very cool!   Congrats on getting it sorted out.   I just spent the last 6 hours rebuilding my 3D printer (had a bent guide rail and it was not nearly rigid enough).

Machines are more fun when they work.   Very jealous of your ability to force metal to your will now.   I will own one of those someday...

[frijolee]

Solid work.  +1 to what Blake said.

[Dvous]

Alright guys the time has come for pics.

So the next thing I did was finish the Y-axis limit switch situation.  I basically did the same thing as the X except I mounted the switches inside a single tube and moved the striker instead of moving the switches, it works great:
[attachimg=1]
[attachimg=2]

So all I had to do to run this thing was build a control mount.  I started with the most redneck monitor/tower mount you've ever seen:
[attachimg=3]
[attachimg=4]

Then I moved forward by adding the most redneck keyboard/mouse tray you've ever seen...and wrapped up by adding the most redneck switch panel you've ever seen!
[attachimg=5]

But, at this point I had a complete machine, so I threw the covers back on and started making chips...project completed...for now:
[attachimg=6]
[attachimg=7]
[attachimg=8]

[Dvous]

Cool!  Did you make one of those cube ball thingys?

Sent from my SM-G920V using Tapatalk

Wow, well done sir!

Yes, I made one of those "cube ball thingys"

I couple years ago I machined a turners cube on my little mill with a rotary table for my girlfriend for our anniversary, this year I made her this (and am doing a really neat stand for it next, I'll post pics when done):

Solidworks Drawing:
[attachimg=1]

Mastercam Toolpath view (one side of the cube ended up being about 20,000 lines of code):
[attachimg=2]

Finished product:
[attachimg=3]

I only squared the block up to about .005" so you can see some overlap between the faces, i've already started filing it off and polishing it...it looks killer.

[freeskier7791]

I couldn't think of the real name.  That looks way cool, and a good test of the machine I bet