I am now officially out of hibernation now the weather has got slightly better and I have been putting together something I have been thinking of doing for a while now, a new variable speed DC spindle drive.
Gathered together the following parts -
1HP DC Motor - Its bigger than i thought it was going to be and quite heavy but good quality DC motors all seem to of a similar size to this. Max RPM is 2000 which is slightly slower than I wanted but will gear it up to get more speed.
DC variable speed motor control board - This is 240V input and will drive a DC motor at 180V up to 8A which will be slightly more than I need for the motor I have got. This is a very good quality board which has a lot of features that I will probably never use but the ones I will be using are the ramp up and down speeds, forward and reverse, and it accepts 0-10V input for speed control so should be easy to interface with my controller so that I can get it working with Mach3.
AC Mains filter - Apparently the motor speed control board needs one of these to clean up the electricity going into it so I bought a 30A one. Bit overkill but the price was right!
Spindle 2 board - Got this from Roy at DIYCNC, I have used Roys boards for everything on my machine and do rate them. The spindle 2 should allow me to send the 0-10V signal to the motor controller. Not tried it yet but somehow I don't think it will be too difficult to setup.
Spindle cartridge - Found this in a box of stuff that came with my lathe, I have re-engineered it and replaced the original spindle which had some odd size taper in it for an ER16 collet version. Was a pretty straightforward mod and the original bearings are very nice quality German ones so should be perfect for what I want.
Toothed belt drive - Gone for a toothed belt drive because....well.... I wanted to and I got them for nothing! Spindle pulley is a 22 tooth which was the smallest that I could get to fit onto the spindle cartridge and the motor pulley is a 72 tooth. This gives me a 3.27:1 ratio which means I should be able to get the spindle running at about 6,500 RPM max. This should be perfect for what I want to use it for but not convinced that it will provide the torque at low RPM so may need to double up the sprockets later to give me an additional 1:1 option. Just have to wait and see! I will be making provision for quick mounting my original Kress spindle to the machine for when I need a high speed option, trying to cover all the bases.
Electronics enclosure - Once I have everything running then I will put together a nice enclosure for all the electronics, want to make sure that it works first!
Ordered some more aluminum plate today to make a couple of mounts for the spindle cartridge so hopefully next week I should be getting close to putting everything together.
I will update this thread as I go so if anyone fancy's building something similar then you will be able to learn from my mistakes!
Photo's below of the bits and pieces and also a quick screen grab from my CAD software of what I have got in mind.
Last edited by HiltonSteve; 26-03-2010 at 12:17 AM.
Sweet. Looks similar to what I was planning, although I'll be using a 3 phase motor and vfd. Any reason for using DC? Where did you get the ER collet with the threaded end or have you made it?
I got the ER collet chuck from Fleabay via China, it came with a straight shank and I machined the thread on etc, 19mm x 1mm pitch left hand! Why is nothing ever simple.....
Last edited by HiltonSteve; 31-03-2010 at 09:54 PM.
Spent another few hours at my DC motor spindle upgrade tonight and I think another couple of hours should see it mounted on the machine and ready to go.
I removed my Z axis from my machine and mounted up the new spindle and motor to it, all went together pretty nicely and pretty much just as I drew it up.
Mounted the motor on a couple of old 15mm linear rails for belt tensioning which may seem a bit over the top but I had a couple of old ones lying around and on further inspection they would not be much good for anything else, certainly made life a bit easier.
Just need to make up a belt tensioning screw tomorrow, get it all back on the machine and wire it up. It looks like it should work so fingers crossed!
Photo's below - think that the bench may need a tidy up after I get it running....
The Following User Says Thank You to HiltonSteve For This Useful Post:
Looking good Steve
We will have to meet up sometime seeing that we are not to far away from each other.
Looking good Steve
can't wait to see some videos, will be doing the same thing but my motor is 4000 rpm, will still gear it 3.1 ratio.
Got the Z axis back on the machine tonight and spun it up, I'd like to say it worked perfect first time but afraid not, lifes never that easy but thats what makes it interesting!
Noticed some vibration around 500rpm on the motor which after some investigation I found that after running the spindle for 5 mins the bottom half of the spindle head was getting a bit too warm. Disconnected the drive belt and turned everything by hand to find that my smooth as silk running spindle head was now feeling a bit tight and lumpy, BASTARD!
Stripped it down and looks like the bottom 2 bearings are either knackered or the inner race has been slipping on the spindle shaft or a combination of the 2. Flushed out the bearings, re-greased them and fitted them back on to the spindle with some bearing fit loctite.
Now all feels smooth again but not 100% convinced that it has solved the problem, will leave it over night and give it a run again in the morning. Got a feeling I will be off to the bearing shop next week!
Other problem is the weight, when the steppers are powered off the z axis now slowly falls down. Thought this may happen and will be ordering a couple of 150mm stroke variable pressure gas springs tomorrow. The stepper drives it up and down fine but not comfortable with it having to shift that much weight.
But.... it does look nice...!
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