Reveiw: Stepmores SM-3040 CNC Router/Mill

[Nixie]

Hi guys, bit of a newb here, but would this machine be good for me? I want to work in aluminium mainly, wood and plastics also but less, to make fairly 3-dimensional parts, that is - create underhangs, hollow/2 sided works. I will be using STL files, only have a WIN 7 machine with USB, and both my space and money budget is low!

I'm pretty novice but im sure I'd be able to get along with cnc given some time and experimentation. Can I expect good quality results with this machine and am I going to need to spend more money on other hardware to bring it up to snuff or is it already good as it is?

Thanks for your help! (in advance)

Chris

[irving2008]

Hi guys, bit of a newb here, but would this machine be good for me? I want to work in aluminium mainly, wood and plastics also but less, to make fairly 3-dimensional parts, that is - create underhangs, hollow/2 sided works. I will be using STL files, only have a WIN 7 machine with USB, and both my space and money budget is low!

I'm pretty novice but im sure I'd be able to get along with cnc given some time and experimentation. Can I expect good quality results with this machine and am I going to need to spend more money on other hardware to bring it up to snuff or is it already good as it is?

Thanks for your help! (in advance)

Chris

Chris

These machines are primarily 2d (cut from sheet) or 2.5d (cut varying depth/pocketing) routing. They will not do underhangs tho the 4th axis option may help if your workpiece is cylindrical. To do true 3d with underhangs you need 5 axis machine such as MINI 5 Axis CNC Machining center: http://youtu.be/NOcxwRUeh_4 but your budget won't get close I suspect.

[Nixie]

Thanks for the response, I think i wasnt very clear before, I realise it wont cut underhangs by itself, what I meant more was say could I cut a figurine or reasonably '3d' object by cutting one side and then another? Mostly I was thinking to cut parts for my motorbike and other functional items which will be pocketed and then flipped to shape the exterior. Is this machine too weak for this kind of work?

Thanks!

Chris

[DarrenGrant]

Chris

I have spent a fair bit of time looking into aluminium milling reading things on-line and some assistance from Eric at stepmores.

Most of the machines can be used for aluminium but to varying standards.

The common basic machines with a 230w spindle (well more of an engraving tool than a true spindle) will engrave aluminium and with a bit of effort to get the right depth of cut and feed speed you might just about cut aluminium but the results will be pretty poor and the spindle is likely to wear out quickly due to the basic bearings. To be honest I would avoid this sort of machine unless you are only working with soft plastics and wood and have modest needs.

The next step up is the 800W type spindle and realistically it would look like this is the minimum realistic option for metal work ideally coupled with ball screw feed system. You will typically get good results for engraving and it will also do some cutting jobs but one issue you have to account for is that when cutting metal you don't need high speed you need torque so that the motor does not stall. As you will be slowing the spindle speed down probably to somewhere around 8000 RPM for aluminium the motor will loose power. The cost of upgrading to a 1.5KW spindle is not huge so is probably worth it rather than having to buy one later.

With this kind of set-up you will get adequate results with aluminium as long as high precision is not essential. The aluminium framework on the machines is sturdy but there will be some vibration, you will probably have to polish surfaces to get them smooth after working.

One of the ways to reduce the vibrations is to have a moving table machine, stepmores have SM-4040 and 6060 where the gantry is securely fixed to the heavy cast base instead of moving on rails. This is perhaps the cheapest way so the best compromise for someone on a tight budget to achieve more accurate results without having to go to the expense of cast iron. If you are going to do a lot of cutting aluminium and accuracy is important then cast iron will essentially eliminate vibration because of the density/strength of the iron. Stepmores offer Iron casting option on those two models.

You can turn your object on the table to cut each side but it does take a bit more effort to do your cutting in a way that makes sure your object can lay flat when you turn it. From what I have seen the 4th axis gadgets that turn the object can easily be turned by hand so I wouldn't imagine they would do very well for metal work unless someone has one and can say otherwise. You can also cut some underhangs using an appropriately shaped tool but you are somewhat limited in what you can do.

[Nixie]

Darren, Thanks for the detailed response! I will look into the 4040 and 6060 then, I think 4040 would be large enough for most of my needs, and I can always divide parts up. But does the moving table vs moving spindle result in less useable space?

So, things I will probably need are: good 1.5kw spindle, ball screw on all axis, potential 4th axis would be nice, at least for wood, and USB input is pretty high on my list. Is the control board from Stepmores good?

I think I'l contact them within a week or so to see what kind of price I can get, TBH i'm nervous about being slapped with huge import duties and other charges, but this is the trade off with paying less by ordering from China!

Chris

[DarrenGrant]

Chris

A moving table doesn't result in less usable space but it does mean the machine requires more workspace as the table will extend beyond the back of the machine when moving so where as a 6040 moving gantry type machine has a set footprint the 4040 & 6060 you will need to allow extra free space at the back of the machine for the table to move into.

I believe that all the stepmores machines have a USB controller but not having one yet I am afraid I can't give any feedback on the quality. I will likely upgrade the controller to a smoothieboard board http://smoothieware.org/smoothieboard as it controls the machine directly rather than rely on a PC running a multitasking OS that is not well suited for real-time machine control.

You will be charged VAT currently 15% for Luxembourg so be quick and make sure it is delivered before January 1st 2015 or you will have to pay 17%. So on a $2500 machine you would be paying approximately €300 VAT.

[Nixie]

If I have this correct, I would take my .stl file, run it through software to generate a Gcode, which i then place on sd or usb, which the smoothieboard feeds to the cnc? does this mean I can keep the PC and cnc separate?

Thanks for the VAT tip, Im actually British, I just live and work here for the moment, so I can have it shipped to either country.

I'll see if I can get stepmores to give me a discount to remove the controller, I guess the first Job would be a smoothieboard enclosure!

Chris