24 replies to this topic

[Phil Hackett]

This was a while ago but it still hurts. The fix was much easier than it looked but it cost 3 days of running down the problem, getting the parts delivered, modifying the machine because the parts (not OEM but better quality and were available in 24 hours not 8 weeks!), and installation. Of course, this happened when the machine was needed the most!

 

 

 

 

[Dennis David]

what machine was this?

[Racer36]

Looks like the ship hit the sand.....

[Phil Hackett]

I wish I had a picture of the screen when the error flashed up and the machine stopped. All those errors were flashing red. I initially thought that either the x-axis motor/encoder destructed or the servo amp died.

 

As it turned out, the cables running from the amp to motor failed. Somewhere I have pictures of those cables and it wasn't pretty with *broken* wires in 2 separate places.

 

One of the advantages of having a "mainstream" system (even though you pay a lot for it) is the support, OEM or independent, that's available. The OEM quoted me 6-8 WEEKS for the cable assembly. I was able to find a company that makes cables for CNC machines, here in the US, and they had the cable in stock... and for less than the OEM.... and better quality than the OEM. The fix was less than $200 for parts and about a day for installing. (that sounds like a long time but all the chip guards have to be removed and replaced. Not a minor job).

 

The machine is a 3-axis vertical machining center.

[Dennis David]

Post a picture of the entire machine if you can.

[Phil Hackett]

Here you go... this machine is 14 years old, bought new in 2005.

 

 

[Phil Smith]

That's looks really expensive.

 

Is a machine that big required for slot car parts? Maybe you manufacture more than just slot stuff?

[Dennis David]

Awesome. Perfect for making weapons of mass destruction.

[Dennis David]

Datron makes a similar "small" mill for 80k

[Phil Hackett]

It was very expensive. The machine has 40" x 20" x 20" travels and a 12,000 rpm spindle, side-arm tool changer, all kinds of control software options. It weighs 12,000 lbs.

 

I was looking for a much smaller machine and when I priced them out they were as expensive as this machine (which was on sale) with less features (think of buying a new Ferrari at new Porsche 911 prices). The advantage of a machine this large is that many jobs can be set-up at the same time and left in place. In this picture there are 10 separate fixtures. You can't see it but the back of the table isn't used so I could get another 6-10 fixtures on the table easily.

 

I learned from a previous CNC machine that bigger is better (up to a limit). The Z axis (spindle up and down) is *very* important and there's no problem with this machine.

 

I have made parts that use quite a bit of the table. One "slot car part" was over 2 feet long, made a gimble mount for a telescope (small one) and some others I can't think of right now.

[Dave Crevie]

That is a pretty good machine. My experience is with Deckel 5 axis machines. Any true 3 axis machine is overkill

if all you are doing is slot car parts. They need to be running 24/7 to pay for themselves. That means a tool changer

working from a magazine and robotic parts changers, and all that can double the price of the machine.

[Phil Hackett]

Dave, I agree BUT when you price out a simpler, smaller machine they're not that much less than a full-featured VMC. There's also resale to be considered: a specialized small machine just doesn't command much in the used market unless you can find "the guy" who absolutely needs one and if finding "the guy" is that much trouble or time waiting for him to show up, the delay of a sale discounts the price.

 

(note the Haas control.... 4 axis)

[Dave Crevie]

Phil;

 

It depends on what you are classifying as a small machine. You are absolutely right about resale value. A name brand

machine will always bring more money. Most important is keeping a good log of machine time if the computer doesn't

have elapsed time recording. Anyway, most people making slot car parts aren't going to buy a 20 X 40 CNC machining

center. The trick is to balance need against price. In reality, the best thing for someone who is going to make 10, 20, or

even 50 parts is actually to work from prints with all dimensioning from a 0-0 datum, and just do it in a simple machine

with a DRO. It is too easy to get in too deep with equipment you don't really need.    

[Phil Hackett]

I only posted the pic because I was asked to. Sonic typically doesn't make onesies-twosies on this machine. It's what the Bridgeport mill (with DRO) is for.

 

When I was looking for machines I was looking for the 20 x 20 x 20 range. I consider those "small". I had already had experience with a CNC VMC that had a 10 x 6 x 6 envelope. It was entirely too small. I consider VMCs smaller than 20 x 20 x 20 as miniatures... they are perfectly capable of making small parts, and do, but they often require proprietary (expensive) and sometimes unavailable tooling and when large production runs are needed not enough fixturing space is available.

[Dennis David]

I like the idea of putting fixture space into the equation. Saves on setup if they are all calibrated in. I had not considered the idea of setting up multiple fixtures but will do for my own small projects

[Dennis David]

My fixture space is about 600mm x 800mm but my z axis is a lot less at only 110mm. Enough for a lot of flat parts. ;-)

Everything is low profile and some of my first projects will be creating my own fixtures.

[Rob Voska]

Use a sub plate with 3 dowels to locate.  Fixtures will repeat, clamp in place quickly & be interchangeable.

[Dennis David]

I'm having a custom t-slot table made.

[Samiam]

David,

 

All this equipment has got to cost a pretty penny. Is your plan to spend all of your children's inheritance? 

[Dave Crevie]

A subplate only needs two dowels for location and squareness. Easier for fixture changing. By the way, this type of set-up

is called "palletized fixturing".

[Dennis David]

Sam, a man's gotta do what a man's gotta do. Plus my son makes a pretty good living as it is.

[Phil Hackett]

Not the cables that failed that started this topic but this was from about 1 year earlier. There wasn't any replacement for this cable so we had to make one up. Still, a small cable like this can bring a very expensive machine to a stop in a big hurry. It's necessary to note that this cable failed in the cable carrier.

 

 

 

 

and a close up....

 

[Ecurie Martini]

I find it hard to imagine what the cause of that kind of failure might be other than a 90 degree turn around sharp corner.

 

EM

[Phil Hackett]

The picture can't show it but the outer insulation became very hard and wouldn't flex. You can see the curvature of where it lived. Since it lived in a cable carrier there was no 90° sharp corner and the only place it did flex was the beginning of the carrier. So, yeah, I guess you're ultimately correct about flexing 90° but there wasn't an object it was flexing around.... if that makes sense.

 

Turns out PVC isn't the best insulation for machinery that uses oil/coolant. We replaced with urethane insulated cables.

[Dave Crevie]

Fortunately these cables usually have color coded wires inside, and in an emergency you can splice it back together. I have

had to do that in the past, both with servo control harnesses and reader head harnesses. Just use lots of good heat shrink tubing 

over all the splices.