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Marlin
14-08-2014, 11:26 AM
Hi, This is my first post (Thank you Lee for your help). My Build project is for a 'Budget Optimum' xyz gantry Router. I am a retired Carpenter/joiner with a 50m2 workshop. My interest is building Musical instruments, primarily Acoustic Guitars and Mandolins. So, only really machining Wood (Exotics), and possibly plastics.
So far, I have built a (800mm x 600mm Table) floor mounted frame from Tubular steel with Side and Gantry rails made from 13mm HPL (Trespa) with lots of 608 bearings and have quite good stability.

It was watching the 'OX' cnc Vid that prompted me to have a go in the first place and have decided on a 15mm x 5mm HTD fixed Belt motion system similar to the 'OX'.

I have now arrived at the 'Buying the Motors and Drivers' stage and could really do with some advice.
Being on a budget I am tempted by the Longs kit of 4 nema 23's 2.2 for a miserly 108 but having read many of the other threads and having had unhappy experiences of (not) understanding Chinese/English instructions... hmmm

I have a few Basic questions..
I would like to 'slave' 2 motors to run the 'X'. Will I need separate drivers?

Can I mix and match with motion options? If I use Timing Belts on X & Y is it ok to use Acme thread on the Z?

There seems to be a huge choice of Nema 23's all with different No.s.. how do I know what is my best choice?

Polar, Bipolar, Unipolar, 4,5,6,8 wires? help..

I am not quite sure what a 'Breakout' board does and as electronics quickly advance has it now been absorbed into more modern Driver boards? (The Spark Concepts new xPRO (US) looks very tempting at $120..)

And finally software.. I am reasonably experienced with Sketchup and have downloaded SketchUcam which seems to bypass Mach3 (being cheap again) to give me the Gcode. I think this will give me the facility's I am hoping for. Is it possible to have Manual control with a Joystick or something.. does only certain Drivers give you that option?
I am sure you can gauge my level of (in)competence from this post. Thanks


:stung:

EddyCurrent
14-08-2014, 12:44 PM
I would like to 'slave' 2 motors to run the 'X'. Will I need separate drivers?

Yes you will but you could use one motor and drive the other screw via a long timing belt.


Can I mix and match with motion options? If I use Timing Belts on X & Y is it ok to use Acme thread on the Z?

I don't see why not, each axis is it's own little 'system', you just need to make sure the parameters are correct in your software so that when told to move 200mm, it actually moves 200mm.


There seems to be a huge choice of Nema 23's all with different No.s.. how do I know what is my best choice?

Obviously choice depends upon your particular application but most people use 3.1Nm motors. My machine cuts wood at 900 x 600 and I used these ones; http://www.cnc4you.co.uk/index.php?route=product/category&path=83_85 They work well.


Polar, Bipolar, Unipolar, 4,5,6,8 wires? help..

This is a useful read; https://www.geckodrive.com/gecko/images/cms_files/Step%20Motor%20Basics%20Guide.pdf
Most people use the bipolar parallel connection.



I am not quite sure what a 'Breakout' board does

Just what it says, it breaks out the wiring from your machine to the controlling PC. If you look at most boards they have a PC parallel port and several rows of terminals. The computer connects to the parallel port and your drivers, limit switches, etc. connect to the terminals. Instead of using a PC parallel port, as these have been phased out now, you can use an interface board such as a Smooth Stepper that connects via USB or Ethernet.


And finally software.. I am reasonably experienced with Sketchup and have downloaded SketchUcam which seems to bypass Mach3 (being cheap again) to give me the Gcode. I think this will give me the facility's I am hoping for. Is it possible to have Manual control with a Joystick or something.. does only certain Drivers give you that option?
I am sure you can gauge my level of (in)competence from this post. Thanks

SketchUcam produces G code from drawings, Mach3 enable a computer to control your machine hardware, G code is the instructions that Mach3 uses to move the machine in such a way that your drawing is realised in wood etc. So SketchUcam does not bypass Mach3, you need three pieces of software basically, CAD, CAM, controlling software e.g. Mach3.

For manual control you can use a device like this; http://www.ebay.co.uk/itm/MACH3-CNC-USB-Electronic-Hand-wheel-Manual-Controller-MODBUS-MPG-For-Mach3-/121118366986?pt=UK_BOI_Industrial_Automation_Contr ol_ET&hash=item1c33379d0a
or there are more expensive ones and some people make their own from X Box controllers and the like.

Finally I would say that if you build a 'budget' machine you will get 'budget' results. From what you have described I would have used none of that stuff, I know there are videos showing MDF made routers and they seem to work but I think you will be disappointed with the results. Have a look at these build threads to get an idea of what you should be thinking about.
http://www.mycncuk.com/forums/253-DIY-CNC-Router-Build-Logs

Clive S
14-08-2014, 01:45 PM
http://www.mycncuk.com/images/misc/quote_icon.png Originally Posted by Marlin http://www.mycncuk.com/images/buttons/viewpost-right.png (http://www.mycncuk.com/showthread.php?p=60746#post60746) Can I mix and match with motion options? If I use Timing Belts on X & Y is it ok to use Acme thread on the Z?

I would not use an acme thread. Ball screws are the way to go. ..Clive

Marlin
14-08-2014, 04:25 PM
Thank you for the comments, some helpful stuff there.
I have very limited space in my workshop and this machine has got to earn it's place. There are many ways to machine a bit of Wood and I may find out that it is just not worth spending hours in CAD to achieve results I could do in minutes with hand or power tools.
I like the fine detail and repeatability that CNC should offer and I do love building machines (6 Bandsaws so far.. some out of MDF.. and very accurate cuts too..). I am quite happy to go cheap to understand and learn what I am building and then do it again with better components at a later time.
My Tubular steel frame is very adjustable and rigid. I have been reading a lot of the build logs on this and other sites including a lot of Youtube Vids but I do realise my limitations and understanding Electronics is my biggest problem area. I am hoping to just take recommendations from other builders as to what components would best suit my project and personal experiences with, say.. The German Longs88 stuff..
Thank you Clive, I was being generic.. I didn't/dont know how connected the different drives were to each other and if they all had to have a similar ratio..
I am still interested in anyone's opinion of this xPRO http://www.spark-concepts.com/cnc-xpro-controller/
Thanks all