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Author Topic: Success! Mini Machining Center under Mach3 control - Video link  (Read 331550 times)

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Offline simpson36

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Re: Success! Mini Machining Center under Mach3 control - Video link
« Reply #40 on: July 08, 2009, 06:06:25 AM »
The purpose of the threaded collar is to preload the bearings. The spindle runs silky smooth with zero play. The bearings are so big, they will literally last indefinately in this application.

I don't understand the purpose of a sleeve, unless you are suggesting a 'crush' sleeve as used for example in older independent rear suspensions (Corvette, etc). Those are to maintain a specific clearance as opposed to preload.

The reason I chose an open frame instead of a solid block is the difference in expansion between the steel spindle and the aluminum head. I rely on the 'spring' of the open frame to accommodate the differential without binding the bearings. I considered a steel or cast iron solid block, but I decided against that because of the extra mass it would add that has to be moved around by the little steppers on the table. Ideal would be a hollow cast iron box similar to the x2 head, but I have no way to make such an item. I did consider using an X2 head casting. The open frame also provides more mounting options. With slotted mounting holes, I can mount the 4th axis anywhere from 0 to 45 degrees on the table. although there are keyways for quick alignment with the x axis.

I've had the motor up to 3,500 RPM so far at 62V. In service, it will run at 72V, but with a 1 ohm braking resistor, so I'm not sure yet what the top speed will be. Without the resistor, it calculates to almost 4,600RPM at 72V. I'm looking for 4,000.


« Last Edit: July 08, 2009, 06:25:17 AM by simpson36 »

vmax549

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Re: Success! Mini Machining Center under Mach3 control - Video link
« Reply #41 on: July 08, 2009, 09:55:10 AM »
YEP the sleeve would go between the two inner races of the bearing just like the Chevy rearend. This would spread the load of the inner races across both bearings AND allow you to tighten up the shaft to the bearings MORE. The standard bearings were NOT designed for much side load so spreading the load across the bearings would help to reduce stress and wear on them.

(;-) TP

Offline simpson36

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Re: Success! Mini Machining Center under Mach3 control - Video link
« Reply #42 on: July 08, 2009, 05:01:05 PM »
Imagine the weight of the armature of an electric motor with a 45mm shaft . That's what the bearings are made for . .  my little X2 is not even going to get their attention . . . ;D

I have the Rutex driving the assembled 4th axis now up to 350,000 steps per second with awesome silent holding power, and decent accel. I can set the accel up higher in Mach by being mindful to ramp up the speed from a dead stop to max RPM if the code calls for same, but that's a compromise I can live with for now.

Still running only 62V 5A on the bench.  Will get 72V  20A when on the mill. Once i get it there, I'll be able to see my max speed and cut some metal with it . . should be fun.


QUESTION (for anyone):

I have a  1 ohm 100W power resistor in series with the motor per Rutex spec.  It is in a finned aluminum housing and it gets friggin HOT!  I have no accurate way to measure how hot this thing gets, but you definitely cannot touch it. How hot do these things run normally?



Re: Success! Mini Machining Center under Mach3 control - Video link
« Reply #43 on: July 09, 2009, 12:05:10 AM »
Simpson,

Those resistors are intended to be heat-sinked, to keep the temperature reasonable.  I would expect probably up to about 70C to be a reasonable max operating temperature.

Regards,
Ray L.
Regards,
Ray L.

Offline simpson36

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Re: Success! Mini Machining Center under Mach3 control - Video link
« Reply #44 on: July 09, 2009, 07:12:02 AM »

This thing is a lot hotter than 70C so I better do something about that.

The resistor was mounted on the outside of the aluminum box that houses the 4th axis servo drive, but it was heating up the entire box!

I have some huge old finned heat sinks from Pentium 3 CPUs. Methinks perhaps I'll bolt the resistor to one of those and mount it remotely away from the control box . .  where I won't burn the crap out of myself by accidentally touching it  :'(

 . . .  -or- . . . I could mount it to the mill itself behind the Z axis post.  That should be able to absorb a days worth of heat and would not result in having longer wire runs to the motor.

 . . .  -or- . . . I may just run without it and risk toasting the drive with deceleration voltage, although in my application, I just don't see that happening since Mach controls the decel rate.

Decisions, decisions . . . .

Offline simpson36

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Re: Success! Mini Machining Center under Mach3 control - Video link
« Reply #45 on: July 14, 2009, 10:19:54 AM »

Below is my solution to the resistor heat issue, FWIW. The fan at the bottom blows into the box and cools the Rutex drive inside and the air exits the top and flows past the resistor, which is bolted to the box along its rear edge. It stays cool enough to touch most of the time.

Final score on the servo drive. With the Gecko I could get a .015 cut at about 700 RPM max spindle speed. With the Rutex drive, I am getting an .080 cut at 1,100 RPM max spindle speed. There seems to be power available to exceed this, but the maching rigidity is now the limiting factor. Needless to say, I am well pleased with that result  ;D

I am sort of a servo junky now and I'm waiting on yet another servo drive, this time a Leadshine 810, to put the small NEMA 23 servo (from iteration 3 or 4 of the 4th axis project) on my X axis.  Now I have discovered a small very reasonably priced ($180) AC servo drive made by the same outfit . .  so probably I'll be playing with that sooner or later . . . my wife just got a new dining set, so I may be able to spend a little more on my toys . .   :-X

Review and comparison of the servo drives I have played with so far is here if anyone is interested: http://www.thecubestudio.com/ServoDriveReview.htm

« Last Edit: July 20, 2009, 03:22:23 AM by simpson36 »

vmax549

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Re: Success! Mini Machining Center under Mach3 control - Video link
« Reply #46 on: July 14, 2009, 03:36:17 PM »
SImpson you are not from the land down under are you??? That is the only reason I know to run the NOTICE  sticker upside down (;-)  LOLOLOL

Good Job, (;-) TP

Offline simpson36

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Re: Success! Mini Machining Center under Mach3 control - Video link
« Reply #47 on: July 27, 2009, 04:48:42 PM »
Project completed!  Here's a new video link showing the finshed 'mini machining center' doing its thing with Mach3.  ;D

Feel free to ask questions or make comments. I tried to keep the 4th axis project uncomplicated so that anyone who wants to build something like this can duplicate these results. I don;t have drawings to share, but would be happy to provide sources and part numbers to anyone who wants them.

Once again, many thanks to all who helped this project along with information, ideas and generally sharing knowledge.  I'm a newbee at CNC retrofits and could not have accomplished this without everyone's help   :-*

Here is the link . . . just pay no attention to my wife's excited chattering in the background  . . she thinks it's  8)   and wants to know how to use it to do her wall art scuptures. . .  which of course it will do beautifully . . . just as soon as I do this one last modification . . which won't cost much . . .  really! :D.

http://www.youtube.com/watch?v=b2-Kdud7eiA
« Last Edit: July 27, 2009, 04:54:59 PM by simpson36 »

Offline Bloy

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Re: Success! Mini Machining Center under Mach3 control - Video link
« Reply #48 on: July 27, 2009, 05:06:37 PM »
That is just SOooo Cool!    Great!

Offline Hood

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Re: Success! Mini Machining Center under Mach3 control - Video link
« Reply #49 on: July 27, 2009, 05:34:04 PM »
Looking and working  great and whats even better is you can now gift this machine to the good lady for her wall art and you can go get yourself a full sized mill while she is busy using that one and not paying attention ;D

Hood