Hi there,
I am Flo from Munich Germany.
Just became a Member of this forum after finding the OX on the Net.
As you can see in my Avatar i already have a cnc , a very nicely build and very accurate machine but unfortunately
the cut area is too small for my needs ( isn`t it always?). Simply lengthening the x would be possible of course but, as i once bought this used, it is hard to find out what the original builder did use, meassurements ...back- engineering is? the right term i think,- sorry i am not a native english speaker.
Anyway, as i hardly need it s 3D ability but more than often cut plywood sheets i am in search of a cnc of larger work area. The OX fits the bill but i have some questions for you:
How fast can i expect to run (not mill - more easy to compare) the machine aprox? ( eventhough my machine runs only 2000mil/min but it is small, my buddies big cnc runs at a whopping 9000mil/min. Of course there is no need to go that fast but i do not want to get bored while cutting bigger file using 0,8 to 1mm mill-bits).
Do the belts or bearings need constant/ regular maintenance? I now use HIwin linear slides and so on but that would bee to expensive on a big machine, but these stay constant in performance for us modellars for a looong period).
How good is the accuracy of the machine aprox?

Sorry if this has been discussed before but beeing a long discussion i might have over-seen it.

Thanks
& greets

Flo

Is any one attempting the build out of MDF? -thought I'd give it a try. I see some assembly issues given the added thickness, but I think they can be overcome.

I'll give it a try and report back. MDF will save alot of upfront cost and hopefully will last long enough to replace with better material.

Hi Flo,

Welcome to the forum.

Check this build, it should answer a lot of your questions: http://www.openbuilds.com/builds/aluminum-ox.592/

Thanks Colin,
still leaves the question for me if it starts shaking when cutting smallish parts with lots of corners at high feeds?
(Think of wing ribs with cutouts for spars, and subspars, holding tabs... on my machine that is nice to look at at aprox 600mm/min but i want to speed it up significantly.)
Guess i will have to wait a little till more vids surface of the machine running...

greets

Flo

Flo, I never cut on my machine anything but foam at a speed of 2000mm/min, using a 0.8 to 1mm bits. Unless I make the cut-depth 0.5mm or less my bits will break, and they did break when I run too fast by mistake. Are you cutting on your machine at that speed with these bits wood?

Belts will need maintenance but not as often as you think. I have a belt on my machine and I never bothered with it. I only retightened it once when I had problem with the stepper motor.

If you look closely at the video you will see that it is not the CNC profile that is shaking, even at very high speed, it is the table that the machine rests on that is shaking.

The profile is completely stable.

Hi Justin,
I use a hf-spindle at 24 000 rpm and i do cut 2mm ply at 600-650 mm with a 0,8mm routerbit, no probs.
I am contemplating though to upgrade to a 50 000 rpm hf-spindle to increase cutting speed. Why you might think?
Well i do have a design build in wood with a geodetic rib construction (meaning ribs go +/- 45 deg instead of 0 deg. ) interlocking noumerous times ... each wing has 32 ribs (wich is quite a lot). Together with my tiny cutting area the whole plane takes 2 hours to cut... boring- especisally if couple of buddies ask for a set too. Still using the tiny 0,8 mm bit gives such sweet,sharp corners .. and is partially necessary as it interlocks with some 0,8mm ply pices too...
Generally i love the outcome of parts cut with those tiny bits.
My "Dust collecting tingy" for example detaches for bit change using a key-hole interlock. When the parts pushed into each other you will not /hardly make out the hairline thats seperates the parts. Using MDF it dissapears completely

Hi Colin
thanks for pointing this out to me, i was not sure what i was watching....

greets

Flo

You can make this go as fast as you want. There is an upper limit for cutting speeds that applies to all machines. A cool think about the openbuilds is you can up the speed by going to a laser, plasma cutter, etc. You could also go to a rough pass at high speed followed by a finish pass. With a good motor and controller you can hit 9000mil/min(286mm/min)... heck my routy hits 1500mm/min and I have pretty crappy hardware.

Hi Dude,
you are right with what you are saying about cutting speed.
So in
I was just wonering, as in a build further up front ( sorry do not have the name now) someone had problems on his x axis.
He was told to reduce accelleration.. while i was watchin the vid it did not look too fast or to hard in accelleration to me.

This is no criticism on the machine or build but as i mentioned before i do "require" fast speed and accelleration for my building/ liking.

why?

I use CamBam and usually generate multiple different cutouts per set of file ( just as everyone else i guess) . Like drillings first, inner cutouts, then outers, somtimes a part is set within a cutout of another to save on material...
So first the machine travells all over the working area to drill attaching holes for the ply plate on the mill, then drills the holes in the parts, moves towards the parts that will be the first "cut outside" parts- the ones that are placed inside a "cut Inside" cut area... so it moves around a lot...
then on lots of parts ( say wing ribs) it has to cut a lot of interlocking-cutouts... like u-channels say up to 8 per rib... without a fast accelleration (very short straights in the u-channels) the cutting time will be arkwardly long.
At the moment my accelleration is at 350mm/secsec.

Again i am not criticising anything, i am simply asking as i am intrigued to build this but have zero experience with belt dirven machines.

greets

flo

Yeah dude I totally hear you. My machine just became very dangerous because of the speeds it runs at. I overclocked my board to 400kHz and now it runs wicked fast. It's dangerous to put your face into the cnc area because the machine moves too fast to get out of the way of it. It is moving as fast as a pick and place machine you see on videos. This is dependent on the chips on the motor controller board. SO yeah you can just pick your board to suit your needs. Your acceleration is about 30% of what mine is set at. I have mine set at 1000 and it's very difficult to move the axes manually because they can hit the end of the machine faster than you can stop moving it. You're talking about extreme speeds here and that's what we're doing in our shops every day. Yes it's brutal to set up and yes you have to be careful what you buy but that's what my routy does and it works on an OX too.

Super,
that is good news to me. I take it that in the case of the ox, it is more dependet on your Motors/controllers than restrickted by the machine itself.
That is what i am looking for since i have once watched the machine of my buddy in real life.
Just so nice to have a fast machine doing your work
Mine is set to conservative speeds and accelleration simply because it is so small...

greets

flo

True. I think the key factor here is the belt drives rather than threaded rod. There are other threads trying to make a rack and pinion, belt-rack and pinion, and some other ideas but nothing final yet. But anyway, at this point we're pushing the limits of what the motor controller chips can do. As far as cutting speeds, I'm not pushing the limits yet but should be able to soon. You can only go so fast with an airplane motor

Hi all,
which controller board would you suggest for this ?
The gSheild is hard to find.

You want something that can power a good NEMA23. I think the TB6600 boards can do 4A per motor?

How many axes can an Arduino BOB handle?

EXCUSE MY IGNORANCE AND ENGLISH, BUT PARTS OF THE FILE IS ALREADY THE RIGHT SIZE FOR CUTTING?

Yes

tks

Hi to everyone out there!

I´m Georg(e) from Germany (Halle/Saale) and following the open builds since a while and I will build my own OX-CNC Router asap (depends when the rails will be back in store - I would like to order right NOW).
I´m curious what you think about this one as the controller board for (not only?) my intended OX : http://www.tbone.cc
The specs and the final price looking to me quite outstanding…, it´s open (!) and can work without an extra PC (if necessary).
My investigations for the milling motor brought me to the UAL 23-RF produced by a Swiss company called Suhner. Will the OX router be capable to handle a 5kg milling motor without extra modifications?

I still have a set of 20t pulleys for the Ox sitting here if anyone wants them. International shipping ended up being too expensive to make it worthwhile for the last guy so maybe someone in the US needs them?

Hello George .I like this UAL 23-RF router spindle. How much it will cost ? Why dont you use a Kress spindle? I have in use one Kress FME 800 (W) and its outstanding. Plus , spare parts are easy to find and its from Germany , i guess ,easy to use and buy for you.

Has anyone with a completed OX tried v-carving some graphics or complex lettering?

Hi,
i had a kress 1050 ( like everyone it seems) and the downside is that it is awfully loud.
Now i use a hf spindle wich only costs aprox 40% more than the Kress but doesn`t need replacing the bushings...and is quiet.
Lighter too at the same power.

greets

Flo