What's on YOUR CNC right now?

[pshupe]

Here is that new thread. All about CNC. Mainly so the builders that don't want to hear about CNC don't have to sift through a bunch of drivel in what seems to be a foreign language.

Here is a pic of my newest CNC machine which is about 1 yr old right now.

Since I took this pic I have jammed a Black Box Storm Vacuum pump in behind the control box.

Cheers Peter.

 

[ihavenofish]

My CNC is on my bench right now, in pieces. I've taken my large XZero Predator machine and gave it some surgery, implants, a new smile, some HGH injections...

I'll have some pics of it partly assembled later this week. Full assembly wont be for another 2 months. waiting on a new Z axis and new ATC spindle.

Anyone want my old ATC spindle? Its 55lbs and 3 phase. That should rule out, well, everyone

 

[Tweaker]

Regarding spindles from that other thread that ran away with CNC stuff...how do you know when the spindle is pushed too far?

The reason I ask is because if I push my Hitachi router as hard as what *should* be doable (1-1.8hp cuts) (this is a 2.25hp router, 2.25 obviously meaning peak usage, not continuous and should handle a 1hp cut at least), the motor sparks and really bogs down.

On my 0.8kw spindle, if I push too hard the bearings groan and sound awful, but the cut is acceptable. I guess ultimately the question is, when are the bearings complaining vs just operating normally?

And to answer the question in the first post...nothing on my CNC right now except a bunch of tools

 

[ihavenofish]

Bearings should never groan. You have something else going on if they are making noise. I find especially with hardware store router bits, there are RPM ranges where they want to vibrate the whole machine to death. Beyond that, the only noise I get is from the cutter (or spindle fan).

Heres an example.

The speed is slow, about 50ipm if I remember, not because of power (it's a 1.1KW spindle) but because that tool is tooooo loooong. It's vibrating a huge amount. like literally 1-2mm. Eventually it broke. That machine also had a floppy Z axis which didn't help. It is also held with double stick tape, which sucks hard. you don't see it with your eyes, but the part gets pushed over a large amount when cutting, adding tot he vibration.

With a 1/2" bit it would have cut with 8x less flex, and probably handled 2-3x the speed if not more.

in comparison

Same bit diameter, but a ball nose, and a little less extension, held with a vacuum, and on an actual mill. no vibration on that first 15mm deep cut, This machine has more torque and less rpm for a similar HP, so its not completely fair, but it shows the difference rigidity makes both in the machine and in the cutting tool and in the setup.

 

[pshupe]

Regarding spindles from that other thread that ran away with CNC stuff...how do you know when the spindle is pushed too far?

The reason I ask is because if I push my Hitachi router as hard as what *should* be doable (1-1.8hp cuts) (this is a 2.25hp router, 2.25 obviously meaning peak usage, not continuous and should handle a 1hp cut at least), the motor sparks and really bogs down.

On my 0.8kw spindle, if I push too hard the bearings groan and sound awful, but the cut is acceptable. I guess ultimately the question is, when are the bearings complaining vs just operating normally?

And to answer the question in the first post...nothing on my CNC right now except a bunch of tools

I work with a guy that's a machining expert and he says you basically just listen to the machine. I thought this was a little crazy but I think he knows the basic speeds and feeds very well and at a certain point to really optimize cutting it comes down to what you hear and see. If the spindle is bogging down the cut is too deep or cutting too fast. If you are burning wood then the speed is too slow or the rpm too fast. Having said that you should always start with the manufacturers recommendations for speeds and feeds. I find they are a bit fast and aggresive for how I cut but it may just be that I'm not really used to how that cuts. I have been cutting shallow DOC but now I want much deeper DOC and less stepover. As I said before I would really like to use most of the cutter length. Clearly Fusion 360 gives you the ability to do that. Also with the manufacturers recommendations the 1x diameter, 2x diameter, and 3x diameter DOC speeds and feeds get you faster the deeper you cut. Don't ask me why but that's the way the math works out.

Here is a feed and speed chart for one of the bits -

I did the math and with a 1/2" carbide spiral bit at

- 1/2" depth of cut I can run about 200 ipm
- 1" depth of cut I can run about 150 ipm
- 1 1/2" depth of cut I can run about 100 ipm

So what I have been doing is experimenting with the 3x diameter speed and feed and then adjusting stepover and listening and watching the machine. It will depend on the wood and how the wood is held down as well. I like using most of the cutter and with the recommendations above it is a quicker way of cutting. The scallop tool path seems to work really well on my machine.

For a profile cut I usually go less than 1x d just because the full engagement of the tool seems to put the most load on the machine. For my 3d carving I usually use a large ball nose like 1/2" with a very slight step over for the final carve and use a 1/2" endmill for the rough carve with a healthy step over to hog out the material.

Cheers Peter.

 

[Tweaker]

So with the bearing noise that I sometimes get, it’s only when there is a load on the router. I was told a while back that it’s because of a lack of power on the router. Seems like everyone has something different to say and it’s tough to know what is actually correct.

As far as listening to the machine goes...that’s all I’ve been doing anymore, since my first machine could never handle the manufacturer recommended feedrates and depth of cuts. My machine now can handle anything I throw at it. I’ve been using screws to anchor the workpiece down and it’s worked well for me. No vibration or parts moving.

I’m considering upgrading to a 3hp spindle actually. It just seems like a better overall system, and the cost is essentially the same as a 3hp router. Yes, it’s a Chinese spindle/vfd but my prior experience with the Chinese setup was excellent. No concerns at all.

 

[ihavenofish]

The Chinese spindle are all over the map. They all look the same too. Its irritating. If you have a supplier that gave you a really nice, one, you want to stay with them.

BUT... noise from the bearings seems like it could be a "problem" with the spindle itself. So you need to try and narrow down what it is first.

The "sound" of a spindle bogging down is very distinct. it's nothing to do with bearings. Its just a "slowing" sound.. lower of pitch.

 

[pshupe]

The Chinese spindle are all over the map. They all look the same too. Its irritating. If you have a supplier that gave you a really nice, one, you want to stay with them.

BUT... noise from the bearings seems like it could be a "problem" with the spindle itself. So you need to try and narrow down what it is first.

The "sound" of a spindle bogging down is very distinct. it's nothing to do with bearings. Its just a "slowing" sound.. lower of pitch.

Yes - I have heard the same thing about the chinese spindles but they are relatively inexpensive, as is most things from China. ;-) The guy I get my machines from says 5-10% of them fail but he orders enough that he has extra in stock and they are good with returns. I have had good luck with mine although I would expect to as I have only had two. One water cooled and one air cooled.

The sound I hear when my machine is overloaded is pretty obvious. It just sounds like it's working too hard.

Cheers Peter.

 

[jvin248]

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Just got this off the bench... A second in a similar shape is on there now but fabric topped.

.

 

[ihavenofish]

Yes - I have heard the same thing about the chinese spindles but they are relatively inexpensive, as is most things from China. ;-) The guy I get my machines from says 5-10% of them fail but he orders enough that he has extra in stock and they are good with returns. I have had good luck with mine although I would expect to as I have only had two. One water cooled and one air cooled.

Cheers Peter.

I'm not talking about the odd failure after some use.

What I mean is that those spindle are made by 500 different companies, priced from $99 to $999. They all look identical, but some are literal garbage - not hardened, not ground, 10 thou runout, AND It may be the $999 one that's garbage and the $99 one that's perfect. You are playing the lottery.

Hence, if you have a supplier that you know makes / sells good ones.. keep em!

 

[Ripthorn]

Yes - I have heard the same thing about the chinese spindles but they are relatively inexpensive, as is most things from China. ;-) The guy I get my machines from says 5-10% of them fail but he orders enough that he has extra in stock and they are good with returns. I have had good luck with mine although I would expect to as I have only had two. One water cooled and one air cooled.

The sound I hear when my machine is overloaded is pretty obvious. It just sounds like it's working too hard.

Cheers Peter.

Who's your guy, Peter?

 

[dcomiskey]

Here is that new thread. All about CNC. Mainly so the builders that don't want to hear about CNC don't have to sift through a bunch of drivel in what seems to be a foreign language.

Here is a pic of my newest CNC machine which is about 1 yr old right now.
View attachment 387297

Since I took this pic I have jammed a Black Box Storm Vacuum pump in behind the control box.


Cheers Peter.

OK, since I know very little about CNC, tell us more about this beauty! What's a setup like that cost?

 

[ihavenofish]

Its a nice little machine. my only concern is how much the spindle hangs down. I guess you did that to get close to the table for thin stock?

 

[ihavenofish]

This was my machine a few years ago now:

This is what it will look like in a few weeks:

Shortened by 2 feet. newly designed Z axis, reinforced uprights. Smaller single phase ATC spindle. Will get a 15 tool tray.

750mm x 350mm vac table surface. Good enough for most guitars and hardware i want to make

New control panel for linuxcnc made from adafruit parts, an ipad screen and 3d pritned case.

Fun Fun

 

[pshupe]

Who's your guy, Peter?

I've purchased two machines now from the same company close to me. They are just outside of Toronto and called CAN CAM. They are very good to deal with and the price is good as well. Their machines are manufactured in China, as are most, but they put them together themselves and do the contol box and wiring locally with excellent components.

Cheers Peter.

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[pshupe]

OK, since I know very little about CNC, tell us more about this beauty! What's a setup like that cost?

It was about Can$9000 for the machine and the vacuum system was another Can $2500 or so. If I had to do it again I would probably pass on the vacuum system. I would probably use just a T-track for hold down and build a smaller vacuum system with jigs which would have been much less expensive.

Cheers Peter.

 

[pshupe]

Its a nice little machine. my only concern is how much the spindle hangs down. I guess you did that to get close to the table for thin stock?

That is the way it was setup when I got it. I had a concern as well but I have had zero issues with it. I purchased this machine because it had a taller Z axis and I wanted to cut guitar bodies that would sit in angled jigs and needed more clearance. I still have to move the Z up a bit but have to work out the best setup to be able to use the tiny short bits on thin material combined with the large diameter long bits with a thick guitar body sitting in an angled fixture. They actually make another model with a higher Z axis travel, so maybe a 3rd purchase may be in my future?? ;-)

This is what I would like to be able to do with this machine -

I need to minimize how far I raise the spindle so I can cut fret boards on the vacuum table but also need to get a 2" long cutter above the work piece in a setup like above.

Cheers Peter.

 

[ihavenofish]

For the fretboards, just put them on a taller fixtures. 2.25" of MDF, vac passage through it, and a gasket on the top.
Now, obviously you need to cut that fixture in the first place closer to the table, so some monkeying around is needed.

It's always easier to deal with "too much" clearance, than not enough, and it keeps things more rigid. reducing overhang by half reduces flex by 8.

That's was one of the main points I fixed with my machine's new Z. it overhung "out in front" too much, and then down too much. In its new form I have 135mm from nose to vac table surface minimum (and 310mm max). The standard ER20 tool holders is 35mm from the nose. A very "short" tool like one for fretboard inlay would put me 70-90mm from the surface. A 1/2" x 2" tool that you'd contour a thick LP body with gets me 50mm from the table.

So, I need to make up 50mm of distance to cut through something, like a body blank. 50mm is a commonly available MDF thickness. you can also laminate anything else to 50mm but MDF is already nice and flat. Stick it on the vac table ON TOP of another thinner sheet of MDF so short vac channel bits can reach it. Cut in some registration, then remove the middleman MDF, seal, and put your work piece on it.

To some this seems like a really big amount of work vs just lowering the spindle, but now I have a vastly more rigid working setup and can push the outline and pocket cutting MUCH harder. You also only need to make that fixture once.

 

[pshupe]

That sounds good. I'll give it some thought. I have lots of room to move my spindle up, as you have noticed. Ideally I will see how much I have to move it up to still cut fret boards. If that works that would solve my issues. I can't completely visualize the higher fixture. I could have a few stacks of MDF cut out in the middle and then a fixture on the top with a casket so the air isn't pulled through 2" mdf but rather like and empty plenum then a 1/2" piece with the gasket. I never thought of that. Thanks.

Cheers Peter.

 

[ihavenofish]

Don't ened to be cut out in the middle really. just a hole or 2.

I just drew up a Z plate for my existing heavy spindle (in the video). "backup plan" (I already own it and have tools...)
With that, my spindle gets 93.5mm from the table.. BUT, the tools are 60mm long, so I can hit the actual table with any tool longer than 35mm. so I wont have to stack up as much MDF.. but all the same rules apply.

That spindle is a monster though. It's the same type on all the large machined from biesse, scm, etc. It can take right angles and saw blades! Kinda why I bought it. but its sooo heavy.