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CNC Conversion lots of Questions!

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Garyrmck:
Hello all,

this is my first post here so please be gentle !!

I am fairly new to metal work. In preparation for retirement in 2 years (or earlier if I'm lucky). I've been putting together a small workshop. All my life life I've worked with my head, but really wanted to work with my hands!!! So now I'm going to do it. At this point I have a SIEG SC4/510 HiTorque Lathe, a 6x4 Metal cutting bandsaw grinder, pedestal drill and lots of bits and pieces.

I would now like to buy a small milling machine. I am restricted in size by the space I have, and the ability to get the mill into place. The mill I am interested in is this one:

http://www.ausee.com.au/shop/category.aspx?catid=64

Now I know this is small, but most of the things I'm interested in are small - telescope parts (my hobby is astronomy and I have my own small observatory in the back yard). In the future I have dreams of building a live steam train when I've developed the skills necessary. The mill will be converted to CNC immediately (I work in computers).This mill has a higher speed than the SX2 here:

http://www.ausee.com.au/shop/category.aspx?catid=59

For small parts (that may have slots that are only 1-2mm wide), would the higher speed be a great advantage, or would I be better to get the larger mill?

The smaller mill has the advantage of full conversion plans being available here:

http://www.siegind.com/news_detail/newsId=33.html

It also has a fixed column and a larger table than the usual X1 mills.

Given my usage, would the smaller machine be OK? I figure if it is CNC, I can take shallow cuts without effort on my part. My ambition is to let it do the work, whilst I sit back with a scotch watching it........

Now would the following motor / driver kits be OK for either of these mills?

http://www.omc-stepperonline.com/3-axis-3nm425ozin-nema-23-stepper-motor-tb6600-driverr-kit-for-cnc-router-p-296.html

or this one - a bit less powerful in the motors
http://www.omc-stepperonline.com/3-axis-19nm270-ozin-nema-23-stepper-motor-tb6600-driverr-kit-for-cnc-router-p-171.html

Sorry for all the questions, but as I am on a budget I can't afford to make an expensive mistake.

TIA and
cheers
Gary in Australia

NeoTech:
My tip is, can you afford it go with the bigger motors.. Holding power and torque is often a bigger issue in those mini mill conversions than speed.

I would say neither of those is a good conversion tho, but if space is a problem, and you are only gonna cut alloys - im guessing they work fine.. it will just take a buckload of time.

Before you choose controller, you need to decide on software. Are you gonna take the Mach3/4 route, Kflop route or are you going with LinuxCNC - TB6600 will work with either one.
But in the case of mach3 and Kflop you will prob. want a USB interface, because finding parallel EPP ported machines these days arent that easy. And if you are going linuxcnc, i would
suggest a cheap MESA card like the 7i90HD and a stepper driver.

I ended finished converted my BF20 mill, and found it lacking, it could do alloys but not touch steel. And that is a plenty bigger machines than those you are looking at.
So just never used it, it was faster hand cranking it on the Aciera machine ironicly.

So, what are you gonna make, is it only small telescope parts, are they all in alloys, do the require high precision, if so, precision needs ballscrews and they are not always that cheap. C7 graded ones is commonly used, but i choose to double up in those cases with an extra ball nut. And that adds cost.

I know this isnt an answer, its just more question to ponder about - before jumping into the pool. =)

John Stevenson:
Go for the larger machine, OK it has a lower top speed but provided you only want to use small cutters you can increase the speed.
That kit you linked to is a joke. You will never be happy using the standard screws. Under CNC they really work especially doing circles and arcs, something it never does under manual moves and backlash will soon appear and it's then a uphill struggle for quality.

They also drive the Z axis from the back and the slides are on the front. What will happen is at each change in direction the head will tip before it changes direction.

Next thing keep well away from those all in one driver boards, for a start they are absolute $hit but if one driver goes and it's when not if the whole board is toast.

270 oz/in motors are more than enough for a machine this size, it's the driver that's rubbish. Also you need to drive the head via a 2:1 belt reduction and not bother with a gas strut.

Sorry if this sounds so negative but been there, done  that, got the tee shirt and been sick all over it and I'd hate to see you start off on the wrong foot.

EDIT Just read NeoTech's post and not sure why he can't machine steel. We take the KX1, which is the same size as the second machine linked in the first post, to shows and machine steel and stainless with no problem. This is running Mach3 and no expensive Galil board which probably cost the same as the machine.

Brass_Machine:
Go with a solid mount column X2. You will regret getting the X1. Go even bigger than the X2 if you can.

Plenty of info on converting the X2 out there. More perhaps than the X1.

Free X2 plans:

http://www.hossmachine.info/ - Ton of info

http://www.cnczone.com/forums/benchtop-machines/168634-cnc-12.html - nice conversion. Plans on this page but read the whole thing.

Eric

Brass_Machine:
Not sure if you access to this model of X2, but I would buy this one if I was doing it again.

http://littlemachineshop.com/products/product_view.php?ProductID=3990&category=1387807683

Yes.. I own an X2

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