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Forum Index : Other Stuff : Resurrecting the CNC router
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Some of you may remember the CNC router I built a few years back. When I sold my place in Mackay I pulled it apart for easy transport, and its followed me to my new home in Toowoomba. I haven't bothered putting it back together for a couple of reasons. First, I was disappointed with the speed, and secondly, it was too darn big. The last few weeks I've needed it to make molds and coil winders for the Axial I'm playing around with, so I decided to put the thing back together. To drive it originally I was using KCam, under Windows. The best I could get was about 400mm per minute. I did try out a Linux based control system called EMC, and it worked pretty good, I could get over 1000mm per minute, but being Linux, none of my favorite CAD/CAM software would work. If I wanted to continue with EMC, I would need two PC's or dual boot, a bit of a pain. KCam under windows was good because I could CAD, GCode and CNC on the same PC. Eventually I wanted to convert this router to chain drive, much faster, but for now I thought I would leave it as leadscrew drive so I could at least get it working for me. The other problem was its size. It had a work area of 500*1000*150mm, and the overall machine was about 700*1500*500. Too big for a small workshop. So I decided to cut it down. Here's the bottom chassis before I took to it with the cut off saw. 
And after. 
I had to cut and machine the leadscrews to suit. All back together, but missing the tool holder, its in a box somewhere, will go looking tomorrow. I've swapped the X and Y axis, so now the gantry moves in the Y axis. 
The PC I used to drive it died just before I moved to Toowoomba, so I needed a new one. A quick visit to the local tip-shop and I picked up this TPG laptop for $80. 
Its got a 1.6gig processor, 480M ram, runs XP and has a parallel port, which I needed to connect it to the microsteppers. I downloaded and installed the latest copy of KCam and set up the ports and motor tuning. As before I was lucky to get 400mm per minute out of it. I thought I would give MACH3 a try. Its another CNC software package to KCam, and seams to have a lot of support, even though its more expensive. I downloaded the demo copy and went through the port/motor tuning process. Holy cow! BIG improvement in speed. Even though MACH3 recommends you dont use a laptop due to power saving pauses in the printer port, I was able to get 1800mm per minute on the CNC table! It must use a different port pulsing technique, whatever, but it sure is fast. I ran a couple of test programs and it worked a treat. Next I need to find the tool holder. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| VK4AYQ Guru  Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Glenn Good to see it coming together again, I look forward to seeing it run. All the best Bob Foolin Around |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Yeah when its up and going you'll have to drop in for a visit Bob. Wait till I get the axial finished, will let you know. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Bit more work done on the CNC today. When I first built it I used sprockets and chain between the stepper motors and lead screws. Chain is a easy coupling mechanism, and it allowed me to play around with drive ratio's, but chain is noisy and has a bit of backlash. Today I changed the Z and X axis to direct drive. The lead screws have bearings at each end, so unless I can perfectly align the stepper motor axis with the lead screw axis, I'm going to need a flexible coupling. For the Z axis I decided to make a gear coupling using the existing 11 tooth chain sprockets and some polyethylene ( plastic chopping board ). By heating up the sprocket with a blow torch and pressing it into the polyethylene I could make a internal spline to suit the sprocket. A bit of machining and its done. 
Its not pretty, but it works. 
For the X axis I decided to make a Oldham coupling. Time to fire up the mill. Machined down some aluminum to make the two end disc's. 
And another piece of polyethylene to make the center disc. 
Then a tidy up in the lathe, and onto the CNC table. 
The CNC table is much quieter now. The Y Axis uses chain to drive two lead screws, one at each end the the gantry, so unless I buy a 2nd Y axis stepper motor, or find a couple of 90 degree gear boxes with no back lash, it will have to stay that way. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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vasi Guru Joined: 23/03/2007 Location: RomaniaPosts: 1697 |
Nice couplings! So, this is how is made the center disc: you make the channels on a square piece to be sure they are crossing at 90 deg. ... You make it spherical after coupling it with the two aluminum ends? It have a hole in the center (sorry, this is how I bother my friends with questions about the things I don't know)? Can't wait to see it in action and specially, making PCB boards - curious to see if you can make smd boards. Or at least, if is able to make one trace between the pins of a PIC. Vasi Hobbit name: Togo Toadfoot of Frogmorton Elvish name: Mablung Miriel Beyound Arduino Lang |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Yes Vasi thats right. I cut it square so I could rotate it 90 deg. Marked the center point and drilled a 8mm hole, to suit the 8mm shaft size. I then used this hole to find the middle line on both sides. Once machined, I assembled the two aluminum end's and polyethylene center onto a 8mm shaft, so it was all lined up correctly, and then turned it down in the lathe to give the nice finish. I like polyethylene, its cheap, naturally low friction, and easy to work with. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
One last modification before I call it finished. The spindle and drive. My original spindle and motor was borrowed from my mill, but it was too slow and heavy, so I bought a cheap Ozito plunge router. It had two problems, it was noisy and the spindle didn't spin true. The noise was just annoying, but the out of whack spindle meant I couldn't do any fine work. So I bought a cheap engraving tool for the fine work. It too, had a out of whack spindle! Just goes to show, you get what you pay for. I did have a collet, spindle and bearings from a dead die grinder, it was pretty good quality and spun true, so I decided to adapt it to suit the CNC router. Machined up a lump of aluminum to support the bearings, so I could fit the new spindle onto the CNC router. For the motor I used a 300watt 24v scoota motor, with a chain drive to the spindle. I'm using a chain drive for now, but I may look at replacing the chain with a couple of O-ring belts in the future. 
Its works well. The motor has more than enough power for what I need, its no where near as loud as the Ozito router, and it spins true. And its all finished, for now. Time to put it to work. 
Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
OK, more work in the workshop. I did try a belt drive for the spindle. Chain is noisy. 
But under load it threw the belt, not a good feature. So I went back to chain. While I was in the mood for building workshop tools, I looked into improving my little lathe/mill combo. Its a neat little bit of gear, but to use the mill I need to pull a lot of the cross slide apart, and VV to use the lathe. 
What I needed was a dedicated cross slide ( also called a combo vice, XY table ). I could buy a nice Dawn model for $200, but while walking around the local Total Tool outlet I found a dirt cheap Chineese made combo vice for $69. It was a piece of junk, but for that money, I could only improve on it. First thing I did was pull it apart and take up some of the tollerances, added a bit of grease, scrapped off paint where it shouldn't be, and put it back together. 
Then I made a table to suit the combo vice and the milling head. Painted black to hide the ugly welding. 
And all assembled. 
Its not perfect but it will do for now. The only problem is the Y axis thread is backwards, so you got to crank in the opposite direction to what seams natural. Gives me an excuse to have a go at cutting threads on the lathe, I've never tried that yet. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Glenn, regarding throwing the belt when under load would suggest to me the shafts/pulleys are not perfectly aligned. But, looking at your workmanship I find that hard to believe. Did you try to fit an end plate to the top of the smaller spindle to stop the belt jumping up? I take it you made the spindle shaft barrel shaped where the belt runs on it. Have fun cutting threads with your lathe, I found there are a few tricks to it like advancing the tool with the compound slide only, set at the correct angle. Do back it out well when reversing or the gear backlash will make it cut and stuff up the thread completely. I just cut 4 gear worms in Acme thread, now *that* was tricky, especially sharpening the HSS tool bit. Klaus |
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| grub Senior Member  Joined: 27/11/2007 Location: AustraliaPosts: 169 |
You could try to cnc convert your lathe, then program it to cut your threads. |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Made a short youtube video or the router in action. http://youtu.be/CDzbbX6V_Sg Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| vasi Guru Joined: 23/03/2007 Location: RomaniaPosts: 1697 |
Awesome! Is fast and powerful! I stared at first model for months!!! Hobbit name: Togo Toadfoot of Frogmorton Elvish name: Mablung Miriel Beyound Arduino Lang |
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