Thread: Alpha Zoot ... new aussie machine on the way!

Greetings all,
Can I ask a dumb question? Whilst I am inside huddled around the heater I have been planning my control box and control panel. I have this idea to have the control panel a bit 'retro' style and use the old fashioned metal toggle switches with a separate LED indicator light. However all of the LEDs I am looking at seem to be 2V and as I will be working from my Xylotex power supply that has 24V output, is their some smart way that I can reduce a bit of the power down to 2V just to power the LEDs?
That way I could use DPDT switches with one side doing the power switching and the other doing the LEDs. Would I need some sort of transformer to reduce from 24V to 2V?
I am planning to use relays for all of my main power switching to keep 240V well clear of the other low voltage stuff.

I am with Rod and find 'electrickity' a bit daunting!

Cheers for now,

Alan

I should have mentioned that I have made a bit of progress ... not much, but very rewarding stuff anyway.

Cheers,

Alan

You know what they say? The only dumb question is the one that is not asked.

You can run an LED off any reasonable voltage, just need a series resistor.

Find the specs for the LED you want to use. Typically they will be something like, 2v at 20mA. To run that at 24v you would use a 1k2 resistor.

Look at this link for a good guide, http://led.linear1.org/1led.wiz

Greg


EDIT: That machine is looking pretty good Al.

Brilliant Greg,

Just what the doctor ordered. Have ordered switches, relays, resistors & LEDs online ... should be here in a few days. Even ordered a 'missile switch cover' for the main switch!

Thanks heaps ,

Alan

Here is a rough sketch of my proposed Control Panel ... it will tuck under the side of my table with a sloping face ... need to draw that up as well sometime.

No labels, but the toggle switches are grey dots ... 3mm chrome bezel leds are the red dots ... the 2 things at each end are d handles.

Can't think of anything else I need to switch ... the main control box will be below this panel and under the table as well.

Couldn't work out how to get a jpg file down to 600 x 600 or whatever, so ended up with a pdf ... sorry!

Cheers,

Alan

JPG resize made easy -

Use mspaint.
CTRL W and put in a new size, normally 50% for both values is a good start.
Save the file and then using windows explorer, hover over the filename (with your mouse pointer) and it will tell you the size and dimensions. Just make sure it's less than 800 X 800 from memory

PS: great work, i love it. I find progress on these machines is always slow. I spent tonight pulling the entire machine apart so i can machine the ends square and make sure the lengths are exactly the same. My mate who cut my ali has a nice saw, but unfortunately not all cuts were square and i found the chassis had a slight warp which caused my X-axis to bind.

sorry for the Long story, keep plodding away and check stuff is square and setup right. Saves lots of time.

/M

Hi Allan,
A couple of ideas for switches.
Coolant for the spindle - if you have water cooled spindle you might want to run a separate coolant switch to keep coolant flowing once spindle is switched off.
Driver Board - I quite often turn off the driver board as it stops heat build up in the motors. It is also good (almost essential) to be able to turn off the driver board when firing up your computer. Windows sends a signal down the parallel port on booting and this can turn on things attached to the port - eg spindles relays. Not an issue if you are using the USB port.
I also noticed the relays you are using are 24 volts. If you want to control things like spindles, blowers, etc through a BOB then you need 5 volt activated relays. These are avaialble for about $10 ex HK and Greg has previously posted links to them.
Perhaps move the handle on the right away from the E stop button.

If you use XP then microsoft has a nice little "right click" image resizer. No need to open another program at all.

http://www.microsoft.com/windowsxp/D...powertoys.mspx

Just thinking about the computer switch. Main power switch won't allow you to boot it up. Unless there is a method I am not aware of. (possible)

Perhaps add a momentary switch and wire it to the one on the front of the computer. That is what I did.

Greg

Thanks Rod & Greg for the suggestions. Have added a Main Board switch and a momentary switch for re-booting the computer.

Greg, is the PC re-boot switch 240V or is it some reduced voltage? The only momentary switch that I could come up with, in the same style as my other 'retro' style switches is 12V 20A. I am having a missile launch cover over the Main Switch and will also use one over the Computer Re-Boot ... wouldn't want to bump that accidently!

In my 'style over substance' approach (!) I have elected to omit a spindle cooling switch at this stage. 8 switches fit a nice grid ... 9 switches upsets the balance!!! Also, I will not be going for a spindle at this stage and if I circum at some later stage (inevitable, you say!) I will probably go for an air cooled one anyway ... still have trouble with the idea of water and electricity being anywhere near each other!

Also at this stage am not proposing to use a BOB, just the standard Xylotex board which has a semi-breakout strip on the side.

Thanks again for your help.

Cheers,

Alan

Alan

I don't know what voltage is at the momentary switch at the front of your computer.

Have not measured it. Probably 5v and may be 12v. Definitely won't be more than 12v and only a few milliamps.

On my computer here I must hold that switch for about five seconds to force it to shut down so I don't think that will be an issue.

As far as machine start up sequence is concerned always start computer and Mach before giving the machine power. And shut down machine before Mach and computer.

I strongly recommend you have a rethink on using a Xylotex on this machine. I believe it would be false economy.

You are putting a lot of work and a fair bit of money into this router. It will fall a fair way short of it's performance potential with an Allegro chip driver.

Greg

Hi Allan,
My recent experience with Morphy backs up what Greg is suggesting.
The Gecko 251's and a 49 volt power supply resulted in speeds of 8metres/min. You will probably get higher than this due to the gearing on your R&P.
The combination of mid band resonance compensation and morphing to single step at higher speeds is probably the reason for the good performance.

Xylotex are great entry level controllers but more suited to small and mid sized machines. There is no point running a small machine at 8m/min because you will not react quick enough to stop a crash.
On a Xylotex the best I can get is 300RPM from a stepper. Of course it will spin up higher but mid band resonance issues and lack of torque will bring you back to this figure. The 24 volt limitation means that the steppers are not getting their full potential.

Downside is the cost. You will pay more than twice the cost of the Xylotex and power supply combo for a Gecko setup.

Greg,
I must admit that I was having some second thoughts about the Xylotex set up. I purchased that with 4 269oz steppers about 9 months ago thinking that I would have the machine built in a few weeks!! I went Xylotex only because that is what I had on the Widgitmaster and I could work out how to make it work! (Stupid reason in hindsight!!)

Is there any way that I can proceed and still use the power supply and the 269oz steppers I have? Everyone seems to be talking Gekkos and BOB's and big steppers etc and most of it has gone over my head.

The other thing that has worried me looking at all the other fine machines coming out of this forum, is that whilst I have a 4:1 ratio on the r&p for the X axis, I only have the Y and Z axis with direct connection of the ballscrews to the motors.

Would appreciate any suggestions.

Alan

PS ... Rod, thank you for your comments ... I was sending this message at the same time as yours came through. Lots of things to think about!

An intersting aside here.
I built a machine with 20 pitch ballscrews and I got 14metres/min with a Xylotex controller. I can tell you that was a toe curling machine to operate - for me anyway.
Steppers have full torque at standstill and then the torque drops off rapidly so a high pitch screw compensates for this. The trade off is that you have less resolution on your machine. This set up was OK for routing timber but it is not something you would do to a mill.
It gets to a point of requiring different technology to gain speed and to do this you need to get into the servos.

Allan, I am not suggesting servos for your machine as a Gecko and steppeprs will give you good performance. I was just adding some useless information so others can understand the differences.

Alan

One of the limiting factors with the Xylotex is that it is limited to absolute max 35v and with recommended 30v max. The kits come with a 24v power supply.

So using the 24v supply is still very limiting. Although you will still get substantially better performance out of the 24v with G251s than the Xylotex.

If I were you I would put the Xylotex up for sale as a whole unit. Adequate for a small machine.

As far as cost is concerned if we compare a 3 axis Xylotex board at $155US against three G251s at $237US plus say $10 for an equivalent basic BoB then it is more expensive but better value I believe.

Regarding the ballscrews, Presuming they are 5mm pitch and assuming a conservative 800RPM that works out at 4000mm/min.

Not startling but very usable rapid speed. And you will probably get better than that.

Rapids beyond a certain point are pretty much useless IMO. Only good for bragging rights. Not much else.

Although I can get 30,000mm/min (not a typo) I use 7000mm/min. That is plenty fast enough.

Greg