Just thought I’d post about my MPCNC build. Selection of photos attached.
I’ll mention good material sources I’ve found in the UK for any Brits interested.
It took me about 2 weeks of non stop printing to print all the parts on my rather old, pretty temperamental Thingomatic. Sadly the build area is rather miniature so some of the larger components were printed in two halves, then fixed together with a combination of superglue, acetone and friction welding [guide to friction welding here]. However this hasn’t seemed to cause any problems.
I use PLA from Faberdashery
Having printed the parts I bought 25mm conduit from Screwfix which measures exactly 25mm with calipers.
This cuts fine with a chop saw [with multi purpose blade]. I used the Vicious calculator and [due to space restrictions] went with what I thought was a 700mm x 700mm cut area. This ended up as more like 680mmsq due to me deciding to use endstops [which I’ll justify in a bit].
I ordered the kit from Vicious. I found the price fine [including the 50 quid postage] given the ease of not having to track all the parts down, and the pre flashed Arduino. If you’re ordering from the UK it’s worth noting that you’re going to be hit by a £50 customs charge which is a pain.
The kit took under a week to arrive and came just in time for my build.
The build was pretty straight forward. I found the instructions on the website very helpful. Obviously use a socket wrench for the larger nuts. Otherwise it’ll take forever and you’ll go mental.
I tend to be heavy handed, and I had a few unsettling cracks when tightening parts. When it says “These can get snugged up, don’t crack the plastic, just snug.”…that’s good advice.
If you use the Screwfix conduit for the Z the nutlocks will need a bit of a shave on the sides and a good whack with a hammer, but they will go in.
With the analogue parts assembled I wired the machine, and discovered that the cables were short for X + Y at my build size. I spent a tenner on 5 x 20cm extenders. I’m not going to list these because it’s a waste of money. Just clip the ends off and solder and tape in extensions [which I ended up doing after one of my extenders melted]. Much cheaper.
Otherwise wiring was really simple with the wires in the kit. Ignore the colours, but pay attention to the clip orientations.
I was a foot short on belt. Amazon sell it for 5m for a good price.
All wired up I ordered a Large LCD from Amazon which was plug and play with the pre-installed firmware. It all worked straight off which was great. Tested with a pen and great results. Setup a grid to test accuracy which was spot on.
My next step was wiring endstops. I know that these are frowned upon by some, whoever I want to be able to mill multiple passes with different bits so intend to use endstops as part of my workflow. Long story short. If you use endstops and you put your clips in the wrong way round, you will short your GND and 5V and fry your Arduino. Which I did.
If you do this then you can get a nice kit from Kookye on Amazon for about £30 with a new non-arduino but perfectly fine Mega, Ramps, LCD [which I didn’t use], stepper motors and endstops. This is a great option if you’re not buying the Vicious kit.
Loading the RC7 firmware on here was fine once I’d tracked down the right LCD library, however I was having issues with manual control off the LCD. This was moving in 4x increments eg 40mm, 4mm and 0.4mm instead of single increments. This hadn’t happened on the old Arduino [now with a knackered power output], so I used AVRdude to clone the old drive. If anyone is interested in doing this I can give you a rundown.
With everything fully wired up and working I printed brackets for my Katsu router. If you use these mounts, beware that the router will clash with some nut head’s on your Z axis. These will need grinding right down. Bench grinder will do this nicely. Don’t rip your Z assembly apart like I very nearly did. Otherwise a very solid mount.
Took a while to get used to Estlcam, but it’s a great piece of kit for free. If you’re working from DXFs you do seem to be limited to 2.5D.
I’m an architect and intend to use the machine for milling complex surfaces for concrete formwork etc. so I need to be able to import 3D models. If you want to do this I recommend using the ‘Block Machining’ option which has the benefit of holding tabs and the ability to better define your workspace.
Briefly on feedrates. I’m using a 1/4" / 6mm collet. My router is set at 17.5k rpm.
For MDF after some testing I run my flat end mill at 1mm plunge depth @ 45mm/s feedrate.
For the ball end finishing passes I run 0.25mm plunge @ 30mm/s.
2mm plunge @ 15mm/s was fine. 3mm was not good. There was no difference in finish between 1mm@30 and 1mm/45 so this seemed like the fastest option. I haven’t tried any faster as it seems fast enough.
That’s it for now. Sorry for the essay but hope someone finds this helpful.