Reveiw: Stepmores SM-3040 CNC Router/Mill

[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

[DarrenGrant]

Yes

The typical set-up is that the controller box that comes with a machine is just basic motor controllers it has no intelligence. The PC using something like Mach 3 software is directly controlling the machine by sending pulses over the parallel port to cause the motor to step. As you have probably read on here this can be problematic for so many reasons but mainly because a PC running a multitasking OS has issues of latency where sometimes it can miss a step because the machine is preoccupied doing something else like re-drawing the image on the screen instead of sending the pulse.

The smoothie board has its own ARM microprocessor that does all the controlling work making the PC redundant. Because the processor is dedicated to controlling the machine it doesn't suffer from the problems a PC controller would. There are 3 ways you can load the Gcode onto the smoothie board...

Save the gcode file on an SD card on your pc and then take it and slot that in the smoothie board.

Attach a USB cable and load the file onto it that way, the best thing is that you can then use the computer for other things or even shut it down as it is not needed once the file is transferred.

Alternatively if you get one with a network interface you can load the files remotely from any computer on your network.

I wouldn't bother asking for a discount from stepmores for removing the controller as the box contains a power supply to power the stepper motors and the VFD speed controller for the spindle. So the actual controller boar inside the box is probably only worth $30 or something.

[Nixie]

Thanks again Darren,
Im gonna look through my options, it seems that Stemores is one of the better chinese manufacturers, But the potential hastle might not be worth it. Maybe a kit/second hand is also good for me so I will spend my time.

http://www.ebay.co.uk/itm/1714913169...%3AMEBIDX%3AIT

This looks intersting, and in the EU!

Chris

[DarrenGrant]

Personally I wouldn't go for the eBay link.

To me it looks like a DIY effort made from box section extruded aluminium and will wobble more than Jessica rabbit. My guess is that the project started off as a little project with a dremil or similar engraving tool and having realised that would them nowhere they have tried to improve the machine by getting the most powerful spindle they could find only to find that the machine shook itself to bits so they have given up and decided to sell it all.

You will notice that the support rails (those two outer bars running down the middle) look thin and have no support. This means when the machine moves to the centre the the rails will flex causing the Z axis to change depending on the positioning.

If you look at the pictures in post #32 you will see that machine has rails that are supported, i.e they are mounted on the solid base with an upright section supporting round bar. This is the next best thing to having square rails as it reduces the deflection of the bar as the mechanism moves to the centre.

The way I see it you have three options, buy a very cheap machine and use it to experiment with machining forget about metal and use only soft materials like plastic and wood and put up with some of the problems and limitations that you will get along the way. Then if you find it is something you want to get more involved in put the machine on eBay and buy something better when you are ready.

If you are serious about making a go of it but have not got the budget to go for a real high end machine then try and get a half decent machine that is built on a sturdy cast base. This should be enough for a reasonable amount of hobby work to an acceptable standard.

Go in at the top and buy an all iron heavy duty milling machine that will do everything including steel and take out a mortgage for it.

[Nixie]

I think you are right, perhaps milling machinist wax and doing some lost wax tests might suffice me. I think il look at some of the chinese stuff on ebay that seems to ship from the UK or Germany, aswell as contact Stepmores directly.

Thanks again, I will consider your input!

Chris

[DarrenGrant]

One thing I would add is don't be worried about importing, I was somewhat hesitant the first time I imported something but now I do it all the time sometimes whole shipping container loads that I wonder why I ever worried about it.

The shipping agents take care of everything it is just a question of how VAT is paid. If you buy something made or sold in an EU country the price you pay will have the VAT included in the purchase price. So you are paying the VAT to the seller and they are paying the government. The only difference when importing is that no VAT is charged on the purchase price and when it lands in the country the shipping agent is legally obliged to charge you VAT on the value of the item and pass that to the government. As the shipping agents don't like being unpaid tax collectors for governments they charge you for the admin.

It is a simple process, usually someone from the local branch of the shipping company in your destination country calls you to say the parcel will land today and tell you how much you need to pay. You already know approximately what this amount will be anyway as you will need to factor it in as part of the cost of making the purchase. Simply pay the VAT immediately to avoid delays causing storage charges and make sure you can take delivery as soon as the agent is able to deliver it.

Just make sure it is a door-to-door delivery service, if it isn't just factor in an estimated €100 for the final leg of the delivery for a pallet.

[Nixie]

I don't mind the importing so much, Eric of Stepmores promises to get back to me tomorrow with prices + delivery for the 3040/6040 by sea and air, so I'l see what this comes to. In fact, here in Lux i've imported from the us before and since the item didn't disclose a value, the tax guy just emailed me asking for an amount!

Last random question of the night: different milling bits of different sizes ect will be better suited to certain passes or materials ect, how do you change 'bits' to perform each step? does the machine prompt one a general roughing stage is completed?

Thanks :)



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