Hi all
Finally got moving on this project.
I have decided to start with the electro-mechanical part of the build first. This is partly due to not having the floor space for the actual machine just yet, but mainly because I want to do a full prototype of the mechanics. I am not finally decided on the gantry design, particularly in regard to the Y-axis mounting so I am going to do a few test of my motors and ball screws first to be sure of acceleration and speed results.
Rather than buy motors from one place, controllers from another, I have bought an entire kit from Ocean Controls in Melbourne. To be perfectly honest, the kit price is a fair bit over the component price if I did a lot of web buying; the simple answer is that these guys are only a few minutes from home, they provide excellent customer service and are very knowledgeable. I basically paid more than I needed to in order to get a local warranty and I am happy with that decision.
I bought a CNC-011 kit as shown here
430 oz-in 3-axis CNC Pack with Sinusoidal Drivers :: Large Stepper Kits :: CNC :: Welcome to Ocean Controls and it arrived a month ago.
2x nice big power supplies
1x little power supply for the breakout board
1x breakout board that has plenty of I/O for limit switches etc
1x cable to suit
3x micro-stepping drivers
3x 410oz motors
Anyway, I spent the last couple of weeks testing various motor configurations and tuning with Mach3. i have settled on 1/8 micro-steps for now, the motors still have good torque at that setting and I can run them at about 750RPM to give me 3500mm per minute on all axis. Not the fastest machine going round but plenty fast enough for what I intend to do.
My test rig consists of the X-axis ball screw bolted to my workbench and hooked up to one motor. I fitted a bracket to the nut and attached a wire rope that runs to a pulley in the roof of my workshop, then down to a 20 litre bucket filed with sand. That gives me a nice load to pull against and is easily adjustable if needs be.
Next the frame
Herewith the first dry assemble of the frame.
This is only rough to ensure the fabricator sent all the right parts.
Looks OK so far, one minor quibble with the alignment holes at one end but overall very happy with what they did. Cost with freight from Sydney was just over $1k. That may sound high but remember this extrusion goes for over $200 per length and I got them to do all the drilling and tapping plus supply fixings.
Anyhow, off to the hardware store this morning to gather bits for making a proper table, then move onto the full assembly.
To do:
- Go 20km across town to the only electrical place that sells the cable I need by the metre
- Tear down an old photocopier, fabulous source of limit switches and optical sensors for free
- Ditto an old 19" rack server, free rack mount case for my electronics and VFD
- Back to eBay for the linear bearings and rails
- Source a 600mm ground ball screw for the Z axis, that's my biggest stumbling block so far.
I have also added a couple of shots of my 2.2kW HuanYang water cooled VFD spindle.
More to come this week, if anyone is interested I am happy to post my plans for the frame.
Cheers