TechnomadicJim's Mostly Printed CNC (MPCNC) Project


#1

I wanted a place to discuss and log my MPCNC build as I’ve nearly printed all the parts and I’m beginning to construct it. I would also like to discuss a possible home for it at the Helsinki Hacklab.

I plan to use a cheap chinese spindle for milling wood / plastics and engraving. Bearing in mind the Lotta CNC isn’t to be used for wood I feel my CNC would be a good addition to the lab if space could be allocated to it ?

I’m about to buy some chip board for the base and start cutting my 25mm pipe into the desired lengths. I’m mostly settled on 120cm x 80cm for the outer pipes for a few reasons:

  1. 80cms is the depth of most tables.
  2. 120cms will allow for 1 metre mill area.
  3. 80cm+120cm = 200cm which is the length the 25mm pipe comes in.
  4. 80cm x 120cm fits 3 times into cheap €12 plywood for the base / sacrifical boards.

Here’s a few pictures from the flickr feed of my progress:

Here’s a link to a youtube playlist of other MPCNC builds.

Here’s my current TODO list:

  • Finish printing the few remaining parts.
  • Buy plywood and cut to size.
  • Cut pipe to size.
  • Research and buy cheap chinese spindle and end bits.
  • Assemble.
  • Find a good home for it.

I’m interested in any comments, suggestions and feedback any of you may have. :relaxed:


#2

Depending on the kind of spindle you plan to use, you may wish to think about how to arrange water cooling. Many high speed spindles are liquid cooled and need an external pump/reservoir for the coolant.
I would be happy to assist in anything i can/you need. Especially should you need some parts machined out of metal, say. But equally in implementing the controls, motion systems and associated power electronics as those are in the line of my past work & education.
I am sure a place in the lab can be found for this machine since it would be a nice addition to the current capabilities.


#3

I’m sure if Helsinki Hacklab is too full of nice toys, some other lab (especially near the center of map of Finland) might have enough room for such a cool tool :wink:


#4

@Kremmen Thanks for the offer of help. Here’s a link to a 500w air cooled spindle I have my eye on : http://www.aliexpress.com/item/CNC-Spindle-Motor-500W-power-supply-mounting-bracket-4-x-Screws/846164469.html

It’s got pretty good reviews and costs only $105 shipped by fedex to Finland. I’m interested in any comments you (or anyone else) may have on these cheap chinese spindles. I hope to be able mill wood, plastics and maybe some aluminium (slowly). Would you think this spindle is up to the task / a good choice ?

@Otter Thanks! There seems to be a consensus that space can be found for it. We are probably going to mount some handles and/or wheels so it can be tucked away under a woodworking bench so as not to take up too much space. :smile:

Project Update: @Depili found us a nice flat tabletop to use as a base as the plywood we bought from K-Rauta wasn’t very flat. It should work well as sacrificial board but isn’t up to the task of the main base. We cut the tabletop down to to 120cm * 100cm which will leave some extra room for the electronics and and handles etc… Next @daned33 and I cut the pipes to 120cm and 80cm lengths and started to put it together but had a couple of issues with some of the printed parts being quite tight and needing filing down a bit. We also broke one of the corner blocks as it was poorly printed as I printed it too fast and there was some under extrusion problems. AFAIK @daned33 is printing a new one as `i write this so we’ll try and put it together early next week. WIll post some more pics then.


#5

To be perfectly honest i have no practical experience of such small spindles. If it has got positive reviews then that should be an indication that it should work at least reasonably.
The torque is given in a slightly opaque dimension of gram-centimeters but if my arithmetic works, that translates to about 0.5 Nm. Aluminium could be a challenge but you never know.
It seems to be a regular DC motor with brushes that will wear out eventually, but that won’t hapopen anytime soon if the quality is at least reasonable. I’d say go for it because the price is not bad.

P.S. I mentioned Kress router motors: http://www.kress-elektrik.com/Power-tools.71+M5aabe1784b7.0.html?&tx_commerce_pi1[catUid]=17&tx_commerce_pi1[mDepth]=1&tx_commerce_pi1[path]=2%2C68
I tried to check the weight of the Chinese spindle but could not find it. The Kress is over a kilo so may be too heavy but it is definitely a quality item and will turn some 29 kRPM where the Chinese one does 15.