Ordered my new CNC machine

[Rochey]

What is it's reposition accuracy? That will be a major key especially for PNP work. Nice find though! that price is amazing! 

I emailed them, got a very fast reply, but it didn't answer my question very well. I think my question wasn't well worded.

I started reading through the product reviews on amazon. Here's a quote.

The cuts are very precise (also purchased the spindle listed here on amazon). They are easily in standard with several hundreds of an inch or higher which is more then I need for most of my prototyping needs.

 

[jsteiger]

That will probably be perfect for what you are doing. I remember the standard for wood was a repeatability from home to anywhere on the table, back and forth, back and forth of .003". Half a human hair! Not to shabby.

It's funny when I calibrate the RTCP software on the Robot is all done in metric so microns. Just leaning on the table throws the needle like crazy in microns.

 

[sahib]

Sh*t....that is cheap! I like how he claims that a 3 axis can do "3D"...while sort of true, pretty misleading description.

It can in the sense that the object will be created on flat plane.

 

[Rochey]

the term I've seen thrown around is 2.5D

It's hardly this: http://www.youtube.com/watch?v=RnIvhlKT7SY

 

[sahib]

Generally yes but not specifically. We used to machine model boat hulls in full 3D, deck being flat. I have some photographs showing it. I'll see if I can find them.

 

[Ptownkid]

the term I've seen thrown around is 2.5D

It's hardly this: http://www.youtube.com/watch?v=RnIvhlKT7SY

I WANT I WANT I WANT!!!

 

[Rochey]

what i love about it, is that the starting weight of the Aluminum is 120kG's, and it finished 3.5ish...

what a waste.

 

[sahib]

You would actually be surprised about the amount of scrap you get back as chips.

 

[Butterylicious]

You would actually be surprised about the amount of scrap you get back as chips.

Messy, slow, tedious work with a fairly steep learning curve.  Awesome results when thangs go right.  I've certainly made my share of rejects.

 

[signalflow]

I've been thinking about one of these for awhile. it works off a dremel so probably not as good as the one your looking at but for PCB prototyping and one offs(which is what I'd be using it for it doesn't look too bad.

http://bluumaxcnc.com/Gantry-Router-Purchase-page.html

-Casey

 

[owel]

Have fun with your new CNC!  Buy a lot of bits, because you're going to break a lot of them at the start during the learning curve.   Been there.

Re: I'm using a Rotozip Router for my CNC... it's not the ideal but so far, it's still working. I would be wary of dremel routers. Underpowered, and maybe good only for wood or pcb routing?  I would love to replace my router with a high-speed spindle... but they're pricey.

 

[Rochey]

The plan is that I'll use the spindle that they supply to made toolholders for other thingsm in HDPE.

that's the plan anyway.

By the way - what kind of accuracy should I aim for with a pick and place? It's probably a little more forgiving than proper CNC.
I think the hardest thing I'll be placing are TSSOP packages, with a pin pitch of 0.635mm, and a pin width of 0.3mm ish.

Assuming that lighter packages will align themselves with teh surface tension of the solder. I think being accurate to about 0.2mm should be enough to make sure the right legs of the IC land on the right pads, without shorting any other pads.

is 0.2mm accuracy doable?

 

[sahib]

is 0.2mm accuracy doable?

Easy. Large industrial robot arms swinging hundreds of kilograms at 1m/sec give that accuracy without a sweat.

But the machine you are buying? I don't know.

Accuracy also does not mean very much alone. Repeatibility is what matters.

 

[Rochey]

What's the difference between accuracy and repeatability.

If it's accurate, then it should repeat itself over and over again?

 

[jsteiger]

Accuracy is how accurate would a machine cut say a 3" by 3" square. Location on the table should not matter as long as the finished part measures 3" by 3".

Repeatability would be say you have a pre-cut part or pcb fixed at 0,0. You want the machine to travel from it's machine home and drill a hole precisely at X1", Y1". No perimeter cutting. If we do this 100 times, how accurately is that hole drilled at X1", Y1". Is it maybe X1.005" sometimes?

Since you plan to PNP, it sounds like repeatability is much more important to you than accuracy. Ball screws, backlash, gantry design, spindle mounting and so on are very important.

Best, Jeff

 

[Ptownkid]

I've been thinking about one of these for awhile. it works off a dremel so probably not as good as the one your looking at but for PCB prototyping and one offs(which is what I'd be using it for it doesn't look too bad.

http://bluumaxcnc.com/Gantry-Router-Purchase-page.html

-Casey

Hey casey...it would seem to me at first glance that there are some better machines out there in that price range...that one is VERY cheaply made and I would not trust it's accuracy/repeatability/durability for a second...

 

[signalflow]

I've been thinking about one of these for awhile. it works off a dremel so probably not as good as the one your looking at but for PCB prototyping and one offs(which is what I'd be using it for it doesn't look too bad.

http://bluumaxcnc.com/Gantry-Router-Purchase-page.html

-Casey

Hey casey...it would seem to me at first glance that there are some better machines out there in that price range...that one is VERY cheaply made and I would not trust it's accuracy/repeatability/durability for a second...

Brian,

Yeah after seeing the one Rochey bought and your valid points I'll probably hold off and do some more research. Mind you this is something Ive been dragging my feet on for quite a while as it's not been much of a priority as it is a luxury.

-Casey

 

[tskguy]

HI all,
I just recently finished my 100% DIY CNC router/mill. This pic was taken before it was 100% completed. Now it has a mic6 cast aluminum table and aluminum z axis.(it was mdf in this pic)
It works really well. I built it to drill microphone capsules! I still am dialing in the fixture to hold down the capsules but so far the accuracy and repeatabilityis outstanding. The biggest flaw is the spindle, its a real crappy trim router from Harbor Frieght. I recently just completed my new spindle, I am pretty stoked about that!
The best part of this is it all started here and I have been down the rabbits hole for over 9 months or so. Be careful CNC is a dark hole to go down. Hey but thats why we all do this right, for fun!

 

[shabtek]

Nice going E!
I am always impressed by your dedication.

 

[tskguy]

Ha you guys probably thought I gave up this audio stuff! I hope to get some capsules ready to test in the next month or so. Shabtek you will be on my shortlist of testers. Thats if you want to build a mic!

Here is a pic of my new spindle. Its also almost all diy(the er16 collet is not) Not shown in the pic is the 850 watt brushless motor that will drive it up to 20000 rpm!!!