Lee, thanks for letting me know.
Jonathan, thanks for the link. Fascinating!
Been at university recently so have not had much chance for router building. I came back on a couple of weekends and made a few bits - stepper motor mounts for X-axis and bearing mounts also for X-axis. I decided to scrap the latter and buy two SBR25-2000mm rails, which have now arrived. No customs charges either
Also had a change of plan with the Z axis. I couldn't get the drive mechanism I've used on the Y-axis to fit at all easily, so I decided to go for the easy option and bought a RM1605 ballscrew at the same time as the above bearings. I got back for Christmas holidays on Friday and on friday/saturday CNC milled the bearing mounts and ballnut mount for Z. One angular contact bearing at the stepper end of the ballscrew, and a normal bearing on the other end.
Somewhat randomly I picked a 42T pulley for the stepper and 22T for the ballscrew, so effectively the pitch is now 9.545 mm. PM752 driver with 3Nm motor as with the other axis and I'm getting 10,000mm/min :exclaim: with 1000 acceleration. That means only 2.5 seconds to travel the whole 400mm Z axis. I might try some other pulleys/ratios but that can wait until I've done the X-axis and found which of the pulleys I have is most optimal...
Backlash on Z is negligible. I've not measured it with the more accurate DTI yet, but the 0.01mm resolution DTI moves just over one division if I move the motor back and fourth one quarter-step (0.012mm)...To be expected really since the mass of the Z axis itself should eliminate the backlash.
All that's left now is to mount the spindle/router, mount the X-axis linear bearings and do some wiring. If I had the metal to mount the bearings I'd probably be 'making chips' by tomorrow morning. Can't wait
I'll add some photos soon.
Last edited by Jonathan; 12-12-2010 at 02:45 PM.
Question: do i need to keep my axis rapid speeds the same as my Y will run at 2000mm/min ?
I've got all the axis' at different speeds on my milling machine, so no you don't need to keep them the same. I'm using about 1800mm/min for the X axis on my mill. It will go maybe 20% higher, but it's not reliable at that speed any more. Possibly the ACME screws are getting worn (backlash has certainly increased) but I'm not sure if that would reduce the rapids.
cheers jonathan :)
i did a couple of cuts in alli and delrin yesterday, nowt spectacular, small pocket with a 3mm single flute,,,,, tickled me pink though to see it work.... my optimisme shot through the roof
i may just get there yet :)
Good to hear that yours is working. I've not tried a single flute cutter yet, perhaps I should. I did the bearing mounts with a 2 flute 5mm cutter using 1mm depth at 200mm/min. Took a while to cut through the 1" aluminium, however it didn't require cutting fluid which left me free to leave it running whilst I made other bits :)
I've finally bought the ER16 collet chuck and set of collets for my big brushless motor. I thought that it'd compliment a kress spindle nicely when I can afford one of those since this motor will do up to 6000rpm, and the kress from 5000 to 25000rpm.
[Meant to post this hours ago - helps if I remember to press 'post' after typing!]
12-12-2010 #37I've finally bought the ER16 collet chuck and set of collets for my big brushless motor. I thought that it'd compliment a kress spindle nicely when I can afford one of those since this motor will do up to 6000rpm, and the kress from 5000 to 25000rpm.
i used my 700w motor to do my test cuts(0.6mm depth) the bind with using that at low revs is the amount at which the revs drop under load, it needs factoring in.
i really need to re-work my 2000w spindle housing to fit the 43mm spindle mount (i bought a boat load of hss 5mm 2 flute of ebay to try in it, nice and cheap)
im not sure the single flute cutters are that important if you can get your revs down, youll have no worries there
my take was that with plastic the bigger the chip the less chance of melting but i am doing a lot of guesstimaiting at the moment, ill give a few diffrent cutters a try and see how i get on (delrin is pretty nice to machine)
I'm going to put one 12mm double row angular contact bearing in - same as I used on the Z axis. Do you think that'll be sufficient?
I still need to buy the ESC for this motor and a suitable power supply. 50V and lots of watts...expensive.
Were the 5mm cutters a one off? The reason I'd want to try a single flute cutter is it should clear the swarf easily. [and why isn't 'swarf' in the spell checker?]
I'll post some pictures in a bit - after the snooker!
Last edited by Jonathan; 12-12-2010 at 11:09 PM.
12-12-2010 #39I'm going to put one 12mm double row angular contact bearing in - same as I used on the Z axis. Do you think that'll be sufficient?
my 700w with the pre-loaded(belleview washers) skate bearing gave a nice finish, i cant see them lasting to long but they are cheap and easy to change
ebay search "5mm slot drills (pk of 10) hss slotdrill uk made" £17 including postage
iv read HSS works well with delrin so i bought two lots of these
I might get those 5mm cutters, or maybe go for a pack with some different sizes.
You read my mind with the 43mm mount - I was just looking at how easily it would fit.
Lots of photos...
Gantry with Z mounted:
Z ballscrew bearing mount:
Bits left to fit + old Z and 4th axis:
Top of Z axis with stepper, 42:22 pulley:
Ballnut, can just about see the mount:
Router bits from Aldi, very cheap:
Another view of Z axis:
Finally the whole router:
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