Marathon Machining Session!

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Marathon Machining Session!

Postby bdring » Mon Jul 09, 2012 2:16 am

I just spent all weekend on my faithful 4x4 router. I cut over 2,000 parts for lasers, ORD Bots and a couple for the plasma. I only went through (1) 1/8 bit and (2) 1/16 bits.

The shop was about 85-90F and the water cooled spindle actually got hot for the first time. I just use a bucket cooler. I set the bucket in a try of ice and kept going.

DSC00246.JPG
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Re: Marathon Machining Session!

Postby lx007 » Mon Jul 09, 2012 12:18 pm

Bart, where did you get your spindle? I'm in the process of building a Kronos KRMX02 CNC and trying to determine which router or spindle to go with.
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Re: Marathon Machining Session!

Postby bdring » Mon Jul 09, 2012 1:08 pm

It is a 2.2kW water cooled spindle that I bought off eBay. I got it from the company that used to be called LoveHappyShopping. They are all the same units and you can buy it from stock at http://www.automationtechnologiesinc.com/

I used to use a big Porter Cable router, but I finally got so sick of the noise. The massive amount of air the Porter Cable puts out also tends to make a mess, especially with wood and MDF. The unit is very quite and well balanced. Most of the noise comes from bit and nut. It is virtually silent with no collet and nut.

It is probably more power than I need. I have never seen it slow down under load. I do not have speed control via Mach3. I just set it on the VFD panel. A Mach3 controlled relay turns it on and off. I have it take about 3 seconds to ramp up and down. You can do active braking too if you want, but you need to add some load resistors.

I use a simple 5 gallon plastic bucket for the cooling. Yesterday was the first day it actually got warm and that was after 5-6 hours of continuous run time in a very hot shop.
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Re: Marathon Machining Session!

Postby bdring » Mon Jul 09, 2012 2:04 pm

Here is a video of the machine running. It is hard to know the actual volume from the video. Most of the noise is the bit cutting the material. The stepper motors are probably louder than the spindle motor.

I nest the parts with about 1.2 bit diameters of separation. This means each part gets its own pass, but there is no left over material between parts. This pass cuts almost all the way through for all parts with a 0.005in offset from the cutline. I don't have to closely monitor the machine because the parts stay put on this toolpath.

I then cut all the parts on a single pass with 0 offset so they get a nice clean edge. The start points on each part are set so they pop off cleanly from the remaining clamped down stock. I still need to pay close attention because sometime a parts goes where it should not.

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Re: Marathon Machining Session!

Postby TLHarrell » Mon Jul 09, 2012 5:27 pm

Very nice CNC. Do you ever mill aluminum or other non-ferrous metals on it? And what size steppers does it run for the X and Y axis?
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Re: Marathon Machining Session!

Postby bdring » Mon Jul 09, 2012 6:23 pm

I have milled 6061-T6 aluminum. I have done some copper and brass. The spindle is designed to be high speed so it is not ideal. Even with a single flute end mill it tends to gum up and not chip like it should. I have a wooden sacrificial base, so I don't like to use too much lube.

The Z and X are NEMA 34 Steppers in the 700-800 oz in range. The Y is a 2000 line servo on a gecko drive. The gecko was really hard to tune, so the acceleration never beat the steppers. The servo is super quiet though.

About 1 year ago I swapped out my original Z axis for a K2CNC Z. After a few years my Z nut was starting to make some resonance noise. The K2CNC had the exact same noise right out of the box. :(

I was thinking a gas spring on the Z might reduce the resonance. A fast Z is the key to completing a job quickly.
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Re: Marathon Machining Session!

Postby artwood_decor » Tue Jul 10, 2012 1:21 am

What speed are you using for aluminum, and how deep for each pass?
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Re: Marathon Machining Session!

Postby sports.racer » Tue Jul 10, 2012 1:31 am

bdring wrote: After a few years my Z nut was starting to make some resonance noise.


I know nothing about your machine, so no clue if this might help, but I do know that this fixed my resonance problem http://grumpygeek.com/?p=915

I used 1/2" ball bearings instead of pennies. Works great.
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