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Re: Using a Shapeoko3 to drill aluminum

Posted: Wed Jan 13, 2016 3:56 pm
by DRobs86
Good luck with the build. What cutting tool do you plan to use? I ask because, as others have mentioned, a router is too fast for a drill bit and and an endmill should be helixed into the material to make a hole. I doubt you will find an end mill for your hole diameter and depth requirements. Even if you did, there would be measurable deflection doing a helical plunge with that much stickout.

Re: Using a Shapeoko3 to drill aluminum

Posted: Wed Jan 13, 2016 6:17 pm
by twforeman
One thing that has been floating around in the back of my mind is to replace the router with a real headstock, kind of like this one:

http://www.sherline.com/33060pg.htm

Unfortunately that headstock weighs 10 lbs.

You might be able to make some changes to it and hang the motor on the back side of the X rail with another carriage plate, but you would need some method of moving the spindle up and down...

Using a sliding spline connection for the spindle drive would work, but at that point you might as well build something from scratch. Which would be an interesting design project to be sure.

Re: Using a Shapeoko3 to drill aluminum

Posted: Wed Jan 13, 2016 9:20 pm
by samc99us
Hmm, that is a nice unit, but not sure how it mounts? And it is getting darn heavy! I noticed most spindles aren't rated lower than 6,000 rpm either and you really want to be down around 1,000 rpm for most smaller drill bits.

I don't like using an end mill to drill holes as it is designed for cutting sideways in the material, so any stiffness issues in the machine will manifest themselves as an eccentric hole. Just not acceptable to me.

Re: Using a Shapeoko3 to drill aluminum

Posted: Wed Jan 13, 2016 10:43 pm
by jimg
FWIW, I still plan to use a drill bit rather than an end mill to make the holes. In addition to the reasons that have been mentioned, bits are cheaper than mills and we have plenty of them around already. They should fit the 1/4" collet of the router fine, but if not, I'm sure I can make an adapter to fit a small drill chuck or something. (We have a 17x20 3-in-1 machine (mill-drill-lathe) in our shop, too.)

As for the router speed, I should be able to use a speed control like this to slow it down:

http://www.harborfreight.com/router-spe ... 43060.html

or just replace it with a Dremel.

-Jim

Re: Using a Shapeoko3 to drill aluminum

Posted: Wed Jan 13, 2016 11:16 pm
by WillAdams
The problem w/ such a speed controller is the router depends on its fan for cooling.

Why not consider a real spindle, preferably one w/ belts and pulleys for speed?

Re: Using a Shapeoko3 to drill aluminum

Posted: Thu Jan 14, 2016 5:23 am
by DRobs86
I agree with Will on this. In addition, it's my understanding that many routers can lose torque when you drop the speed too low.

Have you looked at a water cooled spindle with a vfd? I bet for under 600 bucks you could get a setup like that and have much more control over your speed.

Re: Using a Shapeoko3 to drill aluminum

Posted: Thu Jan 14, 2016 3:40 pm
by samc99us
One interesting thing I noted when shopping for spindles is most are listed as 0-24,000 rpm but usable 6,000 rpm and above. Anyone with a real Chinese spindle care to comment?

Re: Using a Shapeoko3 to drill aluminum

Posted: Thu Jan 14, 2016 6:43 pm
by DRobs86
I can't speak from experience on ythe Chinese spindles, but I do know that some thatbarebon the market are useful at slow speeds because some are used to tap threads and the speed and plunge are synchronized

Re: Using a Shapeoko3 to drill aluminum

Posted: Fri Jan 15, 2016 3:15 am
by Jimf
samc99us wrote:One interesting thing I noted when shopping for spindles is most are listed as 0-24,000 rpm but usable 6,000 rpm and above. Anyone with a real Chinese spindle care to comment?
I have a 2.2kw water cooled. 8000rpm is the recommended minimum. There really is not much torque below 5000rpm. I've read you can damage the spindle/vfd by running them at low rpm. The vfd has a programmable minimum rpm setting. Mine is set to 8000 just in case the gcode has a wrong S value.

Air cooled spindles have a minimum RPM that you must adhere to. You need enough fan air flow to keep it cool else it will overheat really fast.

Re: Using a Shapeoko3 to drill aluminum

Posted: Fri Jan 15, 2016 3:33 am
by Jimf
DRobs86 wrote:I can't speak from experience on ythe Chinese spindles, but I do know that some thatbarebon the market are useful at slow speeds because some are used to tap threads and the speed and plunge are synchronized
Those are vector type AC spindles. Basically a very expensive high HP brushless AC servo motor with encoder feedback. You can run them slow and reverse quickly for tapping operations. Usually found on bigger machining centers.

However I've seen people use smaller DC servo motors or even AC brushless as a spindle. Servo motor and drivers are expensive so it's not something very common yet.

I have a 2.5 HP AC brushless servo and driver that I will be retrofitting on my mill. I believe the motor runs about 2k and the servo driver is another 1.5k. I found them on eBay for $150. Way to expensive to buy new.
I can do rigid tapping on the mill when it gets installed.