First Project - Aluminium

[cchaos]

Hi everyone,

After a lot of reading on this forum and designing (nearly a year by now) maybe its time to show my project to you guys, and ask a lot of questions in the process.

Some of the goals I defined for my project where :
1) Working space at least 180cm x 60cm x 25cm (approx. 70” x 23” x 10”)
2) Build out of aluminium (except for the MDF working surface)
3) One long side must be placed against a wall of my workshop and can not be accessible
4) The Machine must be capable of handling MDF and occasionally aluminium.

The tools that are available for the construction are :
1) Drill
2) Standard that can hold a drill to make a simple drill press
3) Table saw with blade for aluminium
4) Router with aluminium bit

I will start by posting a single picture to give a general idea of what I have in mind. Please feel free to let me know if you see potential problems in this design or ask questions where the design is not clear.

And I already have some specific questions :

1) Stepper voltage and Power Supply voltage :

I have bought 4 steppers (RHT34-740) and 4 drivers (Gecko G203V) from HomeShopCNC.
After reading
http://www.cnczone.com/forums/showthread.php?t=76850
and some other sources the voltage for the steppers is either :
Simple formula : 2.0V * 10 = 20V
More complex formula : 32 * SQR(2.7mH) = 52.58 V
But on YouTube I find this impressive Clip from HAYDN812
"http://www.youtube.com/watch?v=3_qdZB9iGhU&feature=channel_page&fmt=18"]YouTube - CNC Stepper Motor Demonstration
in which he uses the same steppers at 60V according to his comments.

I could order the KL-6520 Power supply from Keling :
http://www.kelinginc.net/SwitchingPowerSupply.html
I already use 4 steppers for 3 axes and maybe will add a 5th stepper for the 4th axis in the future, so the 20 amps would cover that.
However, will the 65V (61.3V at 5A) from the KL-6520 be to much for my steppers ?

2) Sawing aluminium with a table saw :

I have already used my table saw (Festool CS50 with blade for aluminium) to saw Alu profiles without any problem. However, in my construction the sides of the base and the sides of the gantry are made out of aluminium that is 15mm (approx 5/8” inch).
Does anyone know if this will present problems for the tablesaw ?

cchaos

btw English is not my native language so please forgive me any accidental abuse of your language

Similar Threads:

• anodizing aluminium
• Aluminium passivation - for aluminium to be used outside
• Aluminium profile u.k
• Help with aluminium bed for pcb's
• DIY Aluminium milling anyone?

[ger21]

Cut the aluminum 3mm per pass.

[cchaos]

Gerry,

Tanks for the reply. Cutting in several passed will be the solution.

BTW, is my thread in the right forum, or should it better be in the parent forum (DIY-CNC Router Table Machines), since I am not yet actually building ?
If so, can you tell me how to move the thread ?

Cchaos

[cchaos]

Some more pictures of the design.

The machine will be build out of extruded aluminum :
100mm x 40mm x 4mm for the gantry (approx 4" x 1.5" x 1/8")
180mm x 50mm x 4mm for the base (approx 7" x 2" x 1/8")
The sides of the base, the sides of the gantry and the Z-Axis will be build out of masive Aluminum of 200mm x 15mm (approx 8" x 5/8")
(what is the correct English word for "masive aluminum" ?)

Ball screws on the X-Axis and Y-Axis will have a 10mm pitch.
Ball screw on the Z-axis either a 10mm or a 5mm pitch.

I've designed the machine so that the ball screws are Direct driven (because this seems the easiest way and I am a Newby) but it should be fairly easy to convert the machine so that the ball screws are driven through pulleys. (see 3th pic) This would make the machine smaller which is good as I also will have to build a cover for it. Using pulleys would also make it possible to change the ratio between the steppers and the ball screws if that is needed.

In some of the pictures I removed the MDF surface and the side of the gantry to give a better view on the construction.

Do you guys think that the unusual orientation (gantry over the long side instead of over the short side) will create some issues ?

Cchaos

[cchaos]

Rick, from HomeShopCNC, solved my question about the Max Voltage for the RHT34-740 steppers. It seems that 65V will be no problem. Hurray !
Well, in fact his answer was far more elaborated and better explained , but the conclusion is that 65V will be fine.

Now, I still have to decide on a breakout board. Any Sugestions ?

[cchaos]

In the meantime some more hardware for the control box has arrived from Keling :
- Powersupply KL-6515
- Breakout board C11G

Sadly, after testing it seemed that the 12V output of the power supply does not work. The 65V and 5V outputs are fine.

Well, 12V is only needed for the fan(s) in the control box and for the moment I can power them using the 12V from an ATX Power Supply that I made a couple of days ago.

Next step will be to make that control box...

CChaos

[CarveOne]

I have a very similar setup and chose to buy a couple of 3" 120vac fans that will operate off of the standard ac line voltage we have here instead of using dc fans. The Keling power supply I have does not have the 12vdc output, just two 72vdc 20 amp outputs.

It should not be difficult to repair it, or get it repaired locally. Just be very careful of the large capacitors. They can dump a lot of amps if shorted when still charged up.

CarveOne

[cchaos]

For the control box I used the case of an old and broken PC.

First I removed everithing inside (motherboard, disk, power supply, ...)

The case itself exists of :
- An outer steel case = Bottom and Sides only
- An inner steel case = Bottom and Front and Back only
- Steel cover = Top only

I removed the inner steel case and replaced it with a new one made from MDF.
I choose MDF because at this stage I assume I will will make several mistakes, or have so called better idea's that will result in a lot of adjustments. These adjustments will be a lot easier in MDF than in Al.
Once I am happy with the result, I can replace the MDF with Al.

In the long run, MDF may be not a good idea to hold components that will become hot and an Al or plexi front would look nicer too.

CChaos

[cchaos]

CarveOne,

Thanks for the reply, I'm always very impressed with the things you show and describe in your threads.

About the broken 12V output :
I informed John at Keling about the problem, and will first wait for his responce.

Maybe it is easy to fix, but I have no experiance with electronics so I would need a good "How to" to perform the repair myself.

The AC fans are a good idea, however, if I can get my hands on some free fans from discarded PC's I would prefere that. I have no idea what a 220Vac fan would cost.

The capacitors are powerfull indeed. I could see on my multi meter (how is that thing called in English ?) that it took more than 10sec before they where drained after I turned of the main power.

CChaos

[cchaos]

Next step was making a heat sink for the Gecko drivers.

For the moment I have 4 of them, but I want to have space for a 5th one for if I decide to install a 4th axis later on. (The Y axis will be driven on both sides of the table, so 4 Geckos for 3 axis at the moment)

For the heat sink I used a piece of Al profile that I had laying around.

I cut off the bottom, and then cut a lot of fins using my table saw.

Looks good, although the Al is somewhat thin (1.5mm ~ 1/16").
I hope it has enough cooling capacity for the drivers.
I suppose this will depend mostly on the airflow in the case.

The last picture shows how I intend to fit everithing in the case. Still a lot of room at the moment, but I like this because it makes it easier to manage the wires, and it makes it possible to add stuff (2nd BOB ?) if I want to.

Next step will be to fix everything inside and start connecting stuff.

Cchaos

[CarveOne]

CarveOne,

Thanks for the reply, I'm always very impressed with the things you show and describe in your threads.

About the broken 12V output :
I informed John at Keling about the problem, and will first wait for his responce.

Maybe it is easy to fix, but I have no experiance with electronics so I would need a good "How to" to perform the repair myself.

The AC fans are a good idea, however, if I can get my hands on some free fans from discarded PC's I would prefere that. I have no idea what a 220Vac fan would cost.

The capacitors are powerfull indeed. I could see on my multi meter (how is that thing called in English ?) that it took more than 10sec before they where drained after I turned of the main power.

CChaos

Standard line voltage here is 120vac 60 Hz single phase for most lights and appliances. Homes have 220vac single phase for electric ovens, dryers, and airconditioners. I don't recall seeing any 220vac small fans, but have never looked for one.

We call them "multimeter" whether they are analog or digital type.


CarveOne

[cchaos]

Today I completed the heatsink for the Gecko's

Marked the positions for the holes.

Drilled and tabbed the holes.
This was the first time I used a tab, and it went reasonably well. Thanks to the thin Al (1.5mm ~1/16") and the small diameter (3mm ~ 1/8") I suppose.

Then I fitted the drivers to check if everything fits together. It did
I used no thermal compound yet as I first want to check if the all the drivers are working as expected.

CChaos

[cchaos]

Now I have to fit everything in the control box.

I wanted to use some sort of standoffs because this would allow for a better cooling and it could make the cable management easier.

I removed the MDF bottom from the case.

I placed the components on the MDF and marked the position of the mounting holes.

Next step was to drill small pilot holes through the board.

From the back side I drilled counter holes (is that what they are called?) that were large enough to hold the washers and the heads of the bolts that I planned to use. That way, the bottom would stay flat.

Then I fitted all the bolts, washers and nuts.
As I could not find M4 bolts that where long enough to hold the breakout board at the desired height, I used threaded rod and nuts instead.

I mounted the breakout board, the power supply and the heat sink with the 4 Gecko's.

Last step was to put the MDF bottom back into the case.

Next steps will be :
- Find a socket and on/off button, probably from some discarded appliance.
- Get some fans.
- Mount the above in the back and the front of the case.
- Start connecting things.
But that will all be for next weekend...

CChaos

[cchaos]

Gutting an old power supply.

While the power supply (from a PC I used in the eighties) is no longer functioning it contains some usable components for the control box :

1) Fan (12V)
2) socket for power cord

After a couple of minutes both components were freed from their old enclosure and ready for a new and fruitful life.

The 3th needed component I will need, an on/off button, I had laying around.

CChaos.

[cchaos]

The front cover of the control box.

I decided, as this is a prototype, it would be a good idea to connect the motors/switches through the front of the control box.

I have no idea where and how I will connect them, so I installed a whole row of connectors (34) in a first slit the front. They can be used for motors, home/limit switches, and whatever I may need later on.

I included a picture of the type of connectors I used. I found them in a local hardware store. Wires can be connected using screws, or using some sort of plugs. This can be done both from the inside, and the outside of the box.

Another slit in the front is positioned right in front of the heat sink so that fresh air that is drawn into the box is passing by the heat sink. I am not really sure if one slit is enough, but I can always add another one if needed.

The 3th hole in the front is to hold the on/off button.

CChaos.

[cchaos]

Now on to the back of the control box...

I made a hole for the fan and for the power cord connector.

The DB25 cable is also put through the back cover as I have not yet found a small ribbon cable with a male and female DB25 connector. (Anyone can point me to a site where I can buy such a cable ?) Such a cable would allow me to connect the breakout board to the back of the control box, so that I can use a separate cable to connect the control box to the PC printer port.

I also made a small hole so I can power the fan using an external power supply until the 12V module of the internal power supply is replaced.

CChaos

[cchaos]

Wiring and testing.

I wired everything up. This took me a couple of hours.
I also had to replace the yellow parallel cable with another one, as the yellow cable did not work correctly.

And finally, connecting the motors, configuring Mach3 and testing.

Did it work ? Yes it did (well, after replacing the yellow cable, it did )
See the boring (except for me) video in attachment.

Now I can start building the machine itself, but ...
There seems to be a lot to do about Rack and pinion recently, and the long ball screw in my current design is approx 220cm (~7ft). Maybe I want to rethink the design... not sure yet...


CChaos

[jalessi]

CChaos

The power supply you have is manufactured by Antek, it is simple to troubleshoot.

Did you check to see if 12 volts a.c. is present on the brown wires?

If that is ok the transformer is good, next examine the corresponding PCB for a bad solder joint.

The next step would be to test the output of the bridge rectifier for d.c. voltage

If you have d.c. voltage present its time to replace the regulator.

Most likely it is a LM7812 regulator.

See the attached image for more details.

http://tinyurl.com/ykf522n

Jeff...

[cchaos]

Jeff,

Thanks for the clear explanation.

AC is OK at the input side of the 12V module. I tested that already. So the problem is indeed in the 12V Module.

Keling Inc will send me a new 12V module, so I will wait for that.
Afterwards I can make the checks you described on the faulty module.

CChaos .

[cchaos]

Today I received the new 12V module from Keling.
After replacement of the faulty module, the power supply now delivers the needed 12V and the fan in the control box is spinning happily without the need of an external power supply.

CChaos