Hobby CNC, the rotor way

The Something Awful Forums > Discussion > Hobbies, Crafts, & Houses > Hobby CNC, the rotor way

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

I'm halfway through building a probotix cnc router. It's all assembled and the motors move, but I haven't got the spindle mounted and my wiring is dangling everywhere. I've only got a 12"x18" cutting area.

I threw a quick program together for you. 8x6 piece of wood, only cutting .01 deep. XY zero is lower right corner, Z zero is top of stock. Small(1/4" or less) engraver or ball nose endmill will work.

This is with a shopbot post I found. Their code looks really loving weird.
http://ppl.ug/Nmhox8Noz6w/

Here it is in generic g-code.
http://ppl.ug/8rBDqUxTh08/

# ¿ Jul 14, 2013 05:44

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# ¿ May 2, 2024 07:51

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

You want a TB6560. Super cheap, 1-4 axes, controlled through parallel port. There are issues with build quality, signal noise, etc. You won't get blazing fast speeds or maximum power out of it, but you can't beat the price.

You can get the basic controller for around $30,
http://www.ebay.com/itm/CNC-Router-...=item4613b55d0d

Or a bundle with some small motors and a power supply for around $100,
http://www.ebay.com/itm/Free-Shippi...=item2ecaa8dff2

# ¿ Oct 2, 2013 04:54

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

Don't waste time with machine shops, call metal recyclers and ask them if you can buy scrap metal. It'll be way cheaper than buying new, but you won't know what alloy you're getting if that matters.

gently caress any aluminum that isn't 6000 or 7000 series. :colbert:

# ¿ Oct 23, 2013 19:57

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

quote:

The mill uses stepper motors and they can cut dependably to a tolerance of +/- 1/5000th of an inch

I totally believe this 100%.

Loving Africa Chaps posted:

I'm not sure why you'd need 5 axis unless you like impellers because thats all i've seen them make

People who don't understand machining think more axes = better.

5 axis is great for holes and fittings at odd angles and off centerline. Transform plane milling is so easy.

oxbrain fucked around with this message at 21:12 on Nov 21, 2013

# ¿ Nov 21, 2013 21:07

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

You can use the A and B axes to rotate the part so you can do 3 axis milling at different angles, that's not too difficult. Doing true 4th or 5th axis profiling is a gigantic pain in the rear end and the only CAM software that will do that is expensive as hell and most machine controllers won't do it well anyway.

For $3k you could get a 3 axis mini mill, a cnc conversion kit, and a mini 4th axis. Another $2-4k will get you a copy of OneCNC, which will do all your 3 axis and some 4 axis stuff.

Or you could drop $20-50k on something more industry standard like mastercam.

# ¿ Nov 22, 2013 07:13

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

Speed, power, and build quality. Cheap controllers start skipping steps when you run them too fast or when they're too hot. Now your computer thinks the machine has moved further than it has and everything gets progressively more hosed up. Bigger controllers can drive bigger motors too, which lets you use less reduction from motor to axis for even more speed.

The only backlash I could see is if it can't stall the motor, which even the chinese special can do no problem.

# ¿ Nov 23, 2013 03:04

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

Do you have a grinder and a steady hand? Relieve the shank of the endmill ~.015" in diameter above the flutes to 3/8" length. That will keep the shank from rubbing as you cut the lower parts.

Or buy a longer endmill.

# ¿ Mar 7, 2014 05:05

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

http://www.mscdirect.com/product/37289741

# ¿ Mar 8, 2014 01:44

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

Drilling up to size might be what screwed you. Unless you're perfectly on center and the drill geometry is perfectly balanced it'll try and walk. With more engagement area it can average out better.

I'd either buy a reamer or mill it.

# ¿ May 14, 2014 19:05

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

Vacuum chucks are a pain in the rear end. A couple strips with the profile milled in will make good enough parallels to clamp down on.

I'd make the whole thing using side tabs, then mill or saw them off at the end. You'll get a lot of chatter, but the bead blasting will cover that up.

# ¿ Aug 13, 2014 00:13

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

Oh those are way smaller than I was thinking. Mill it from a bar in a 4th axis.

Basically what this is doing,
http://youtu.be/ztDQMeinfAM

edit: I am not a cheap machinist. :colbert:

# ¿ Aug 16, 2014 07:29

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

I bought one of those ebay boards and never got more than a couple inches per minute out of any axis before it would miss steps. I'm saving up for a better control setup and working on other projects in the mean time.

oxbrain fucked around with this message at 16:03 on Oct 6, 2014

# ¿ Oct 6, 2014 16:00

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

gently caress arduino, get dedicated hardware. Planet-cnc makes controllers that take g-code over usb and generate a step signal at a much higher rate. Like several orders of magnitude faster.

Buildyourcnc.com sells a 3-axis version for $75.

# ¿ Oct 14, 2014 04:08

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

Drive ratio is based on required torque. With micro-stepping the resolution is significantly smaller than the repeatability of the machine anyway. If you're doing 3d printing and a touch probe, go for belt drive. It's a lot cheaper, and is plenty accurate.

A hobby mill won't be doing anything where cutting fluid would matter. They aren't rigid enough to drive a large enough tool to get that kind of surface speed. Unless you're still using HSS. :corsair:

# ¿ Oct 18, 2014 00:25

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

Most of the world calls it cable carrier. It's cheap it you buy Chinese. This should work.

http://www.ebay.com/itm/390917609516

# ¿ Dec 15, 2014 21:40

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

Height x width since they will be wider than tall. You want everything to lay flat side by side with a little wiggle room in between so they don't rub off the insulation. Tallest cable is 3/8" and combined width is 7/8" and 1-3/8" so this and this should fit nicely with spare height for a 1/2" cable if you ever need it. If overall height is an issue, multiple runs of this 10x15 side by side would be a bit shorter.

Calculating lengths can get really :spergin:

so just buy more than you think you need. Double the axis lengths and then add a bit of margin.

# ¿ Dec 16, 2014 02:30

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

Yes, much less, but then you have to think about math stuff. Like I said, it can get really :spergin:

. In an ideal mounting situation the minimum will be the bend length plus half the stroke length, plus one fixed segment on either end for mounting.

# ¿ Dec 16, 2014 03:52

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

rotor posted:

thick rods, indicator studs, swingin back & forth. that post has it all.

If there's one thing I've learned it's that machining is basically all dick/sex jokes.

# ¿ Jan 3, 2015 00:42

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

For most purposes you can get away with a really small amount of air. With a small enough nozzle you could get away with a good airbrush compressor. 1-2scfm would be plenty.

# ¿ Feb 4, 2016 19:07

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# ¿ May 2, 2024 07:51

oxbrain: Aug 18, 2005; Put a glide in your stride and a dip in your hip and come on up to the mothership.

There's a reason it's hard to find small indexable end mills. Inserts are never as sharp so you get higher side loading. They will never be perfectly aligned so you get worse finish in side milling. They can't helix around the tool so you get a big solid edge slamming into the cut all at once, which is terrible for vibration. They're great in large diameter tools where solid carbide would be really expensive and in big machines that can handle a big enough cut to keep several inserts engaged.

If you're having issues with machine rigidity a smaller diameter tool will give less side loading for the same cut as a larger tool. A 1/4" carbide end mill will be similar in price to a 3/8" or 1/2" HSS tool, but will almost always give better performance.

# ¿ Jan 7, 2017 05:16

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