Jul 29 2008
I have received another set of bearing holders (Thanks Jaak!!). Yesterday I mounted 2 off them at the Y-axis and I made another nut from plastic. I also made a bracket from some scrap rvs to mount the stepper. The coupling with the spindle is made from a piece of scrap brass with some bolts.
To protect the axis I’ve put some inductive end sensors on it, and on the back I’ve made a cable duct for the cables from the Z-axis.
Aug 21 2008
I made another 2 stepper drivers:
Yesterday I made a new motherboard. The old 1 had a few design flaws in it. The new one is for 4 axis so I don’t need to build another one if a forth axis is added.
Circuit:
Pcb:
Partlist:
|
Name:
|
Value:
|
|---|---|
| R1, R2, R3, R4 | 4K7 |
| R5, R6, R7, R8, R9, R10, R11, R12 | 470R |
| R13, R14, R15, R16 | 330R |
| R17, R18, R19, R20 | 3K3 |
| C1 | 4700µF |
| C2, C3 | 100n |
| D1, D2, D3, D5 | 1N4004 |
| IC1 | ULN2803 |
| IC2 | 7805 |
| LED1, LED2, LED3, LED4, LED5, LED6, LED7, LED8 |
LED groen 5mm |
| LED9, LED10, LED11n LED12 | LED rood 5mm |
| OK1, OK2, OK3 | PC849 |
| TR1 | Transformer 1.5VA 9-20V |
| X1 | 25p sub-d connector |
| X2, X3, X4, X5 | 3p printkroonsteentje |
| X6 | 5p printkroonsteentje |
| X10 | 2p printkroonsteentje 230V |
Sep 06 2008
I designed the pcb for the stepper driver. It uses an L297 and L298 ic. The circuit I used:
Partlist:
|
Name:
|
Value:
|
|---|---|
| R1, R2, R3, R4 | 1R 3W |
| R5 | 100R 5W |
| R8, R9 | 10K |
| R10 | 25K trim potmeter |
| R11, R12 | 22K |
| C1 | 1000µF 50V |
| C2, C3, C4, C5, C6, C7, C8 | 100nF |
| C9 | 3,3nF |
| D1, D2, D3, D4, D5, D6, D7, D8 | MUR440RL |
| IC1 | 7805 |
| IC2 | L297 |
| IC3 | L298 |
| J1, J2 | AMP vlakstekker |
| J4 | 3p pin header |
| X1 | 3p printkroonsteen |
| X2 | 5p printkroonsteen |
| X3 | fan connector |
| F1 | 4A fuse + holder |
| M1 | 40mm 5V Fan (optional) |
Sep 07 2008
I finished the Y-axis and made a bed from epoxy coated plywood.
I also reinforced the pillars.
Oct 11 2008
Today I made a pcb with capacitors. On the pcb I soldered 12 3300µF 100V capacitors. I bought these cheap on a radio flea market.
Nov 02 2008
This week I have build the drivers in to the case.
I also finished the front panel.
The backpanel is almost finished.
On the right there are 3 connectors for the steppers missing. I still need to order those.
May 23 2009
I bought a Proxxon micromot for the milling motor. The micromot doesn’t has a speed control build in, so I build one myself based on some recycled parts.
Pictures:
The Proxxon:
The clamp I made for it:
A video of the x-axis working:
I’ve got the Y axis working to but with the Z axis there is something wrong with the stepper.
Jun 22 2009
I have had a new Z-axis construction made (Thanks Jaak!). This needed to be done because the old one had 2mm of play on it. The new Z-axis is based on a compact cylinder.
Drawing:
Video of the Z-axis working:
Aug 17 2009
The relays I used as “emergency stop” relays had some trouble with burned and sticky contacts. I replaced it with a bigger 40A relays but that also got the same problems (probably because of the inrush currents). Then I decided to make a solid-state relays with 4 TIP2955 transistors.
The circuit:
To drive this solid state relays and provide 12V for the fan in the back of the case I made a 12V power supply. On the cnc there will be led lighting, and that is also powered by this power supply.
Circuit:
The traces on the underside of the ssr are reinforced with wire so it can handle more current.
I also painted the top of the case.
Aug 21 2009
After a long time I restarted building on this power supply. I found a circuit where I’m going to base it on.
I’m not going to use this circuit exactly, but the main part I do.
In this design they used TIP142 transistors. In my version I used MJ2955 transistors. I was doubting if I would change the design or change the transistors on the heat sink. After a lot of thinking I opted for the second option. The new transistors are mounted directly on the heat sink, where the old ones used an bracket. This should provide a better cooling.
I didn’t trust the big capacitors I first planned to use any more. 1 of the 2 is so dehydrated that if you shake it you hear the inners rumbling louse. Instead of buying new big capacitors I opted to buy a few smaller ones. This is cheaper and gives a lower ESR. To mount them I made a pcb. Per side I use 3 capacitors of 3300µF 100V. That gives a capacity of 9900µF per side, this should be more than enough.
The next update will be the analog print. This design is 90% ready so it should not take too long (if no other project gets in between.)
Dutch 