CNC Power Supply

[hemsworthlad]

So a question, which one of the limit switches will fit best? Smaller one or a larger one ? With or without the roller ? Short or long lever ?

And generally what do you think about the gear so far ?

Hi Tomov,

The switch's I would choose are the one's with rollers( the 4th from zero on ruler) I have very similiar on my Z axis and it works good. Depending on how you mount them on the machine most of the ones with levers would work ok but the roller ones just seem to work nicer to me.

The cable doesn't look sheilded, if it's not I wouldn't use it.

Connectors look good.

[Tomov]

These are the non-shielded cables which I have. I'll take that as the shielded cables are the better ones. When the time comes, I'll try both of them (gotta find out where on the connector to solder the shield wire). Here is the 4x0.75 mm2 shielded cable:


What do u think ?

[hemsworthlad]

Dont use any unshielded cables for control signals like motor wires or limit switch's you will only come to regret it at some point.

If your unlucky enough to experience noise issue's it will drive you crazy and for the sake of a few pounds more It's just not worth the potential for hassle.

If you use sheilded cable along with good Star grounding then you'll be ok but try to skrimp on things like cable and your wide open for a life of missery and machine that appears possessed.!!

Edit: Only connect one end of the sheild and take it all the way back to your main ground point. Same for every cable take them all back to the one ground point.

[bobsch]

These are the non-shielded cables which I have. I'll take that as the shielded cables are the better ones. When the time comes, I'll try both of them (gotta find out where on the connector to solder the shield wire). Here is the 4x0.75 mm2 shielded cable:


What do u think ?

That cable should work. The bare wire is in contact with the foil around the wires. Connect it at the common ground point for your system, leave the other end unconnected (ground loops will drive you nuts). The only possible problem is that the foil shield won't stand up to a lot of movement, the foil tears. Braided shield cable are better if the cable is going to be kinked or bent a lot.

[JD_Mortal]

Those cables with foil are meant to be crimped with a shielded connection. Both the center (bare wire), and the shield should be connected at the crimp-connector.

Braided is better for durability, and also due to the fact that it absorbs RF noise in a wider range. The foil is limited to super-high frequencies, as it is thin and solid, like a capacitor film. (Dual-shielded often have both foil and braid, with braid being the outer shield, and foil inside. Both help reduce capacitance issues and cover nearly all RF noise.)

Additionally, if you find that signal noise is an issue, you can use ferrite RF choke coils, as you often see on power-supplies which often have RF switching noise.

[Tomov]

A little update. I found that two types of cable in one of my catalogs.

1. 4 x 0,75mm2 + braided copper shield, covered with Sn:


2. 4 x 0,75mm2 with braided shield (w/o PVC wrapping between shield and the conductors):


The first one is made for powering production lines, industrial machinery, etc.
The second one is rated "communication cable". But since there is enough wire diameter and insulation..

Which one will fit best ?

[hemsworthlad]

First one will be better at handling movement due to pvc between braided sheilding but both will work ok, if not much cost difference then go with first one.

[Tomov]

Hey Guys!

First of all ... Happy New Year!

During the holidays I made some corrections to the design of the CNC machine. Now the Z axis distance is set to 80 mm (80mm + 20 reserve for adjustments). I moved the Y axis rails on top of the steel profiles (just as you suggested), lightened a bit the whole gantry and a little change to the router holder. As soon as I assemble the construction, I'll post some rendered images... Any day now

[Tomov]

Here it is, with the general modification - as you can see on the steel frame underneath the table... the Rails are mounted on the top side of the steel profile:



I'm thinking to "squeeze"the gantry a bit to tighten up the construction. As a result the X axis distance will reduce by 20 mm per side, which is fine.
Therefore the Working area will be:

540(x) x 750(y) x 80(z) mm

So ... what do you think... I'm working on better quality images btw...

Ooh and take a look at the spindle mount... is it better than the first design ?

[mmcp42]

just read through the entire thread
good luck to you
you seem to be doing all the right things!

[Tomov]

Here we go again. There's a photo of the corrected gantry. I think it went out quite well. The dimensions of the working area shrunk a bit but that's fine. The X axis movement is reduced by 50 mm.

Here it is...


A link to the actual size image: http://img404.imageshack.us/img404/3...crouterbig.jpg

I'll keep you in touch with more photos and will update the thread when I got any of them new parts

Right after I'm done with the design, I'll post drawings to all parts and instructions for the assembly if you're interested

Yet another idea.... instead of using distribution box for the electronics... I found at my local electronics dealer, an enclosure made of steel.. suitable for the Gecko 540, only to add one fan hole:


...what do you think ??

[hemsworthlad]

Hi Tomov,

I can see a problem.? The bed will flex if just supported at the ends like that.!

You really need a frame for the bed base material to fasten onto if not even thick base material will bend and flex when plunging or drilling.

Without a doubt it will flex if left like this.!!

Also I would not use unsupported rails for the Z axis or any axis for that matter.?

Remember a machine is only as good as it's weakist link, in this case, no point having supported rails on X & Y if the Z flexs due to unsupported.

[Tomov]

hemsworthlad, nice to see you

I will add support pieces under the bed, will post photos when start to assemble it for real.

For the unsupported rails on the Z axis...it's a long story, will leave it this way for test purposes only (like the threaded rods). I will use supported rails in the future.

What do you think about the spindle hold design and the enclosure ?

[hemsworthlad]

Hi,
Both look ok to me, yes I remember now you saying about Z rails for testing purpose's.
Just remember everything attach's to the base frame so get this wrong and every thing else will be wrong. . . . Take your time.!

[Tomov]

Thank you, for the advices. As soon as my exam session is over I can start doing some real work on the mechanics. Until then I will work a few things on the electronics stuff so the last thing will be to order the gecko drive. I will upload images of my progress

[Tomov]

A little update...
...just received the bearings for the threaded screw:



...all six of them SKF 6000-2Z Energy Efficient radial roller bearings 10x26x8 (d x D x b) mm

And.... finally.....I'm ready to order some new type of cable to supply the stepper motors:
There are two options:

1.
Copper wires, PVC insulation, PVC covering, Sn covered copper shield and silicone outer coat.
The price is: about $ 3.00 / per meter

2.
Copper wires, PVC insulation, PVC covering, Sn covered copper shield and PVC outer coating.
The price is: about $ 1.60 / per meter

The both cables are: 4 x 0.75 mm2


The General question is: Which one ??

...btw I'm thinking about the one with the silicone coating... don't know why... but on the other side the price is double so... Which one will fit best