X1 CNC convertion

[HS93]

Hi I have just finnished the hardwear on my mini mill X1 , I decided to use belt drive as I did not want the steppers to stick out to far and I also wanted to have folding handels so I coud use it manualy. I used thrust bearings nad ball bearings, this makes a big difference on this mill and I think if was not going to convert one to CNC I would do this mod as it makes a difference.

Peter

[HS93]

Anothere couple of pictures. also first test under power

http://uk.youtube.com/watch?v=vvNn0qE0KJc

[HS93]

I did the mounting parts for a mate who who did my electrics, He wanted direct drive, they had ball races and thrust bearings , the pitures show the mk1 mount and the finnished mount

[Brass_Machine]

Hey Peter,

Nice looking conversion you got going there. Did you design it yourself or is it from plans. What size steppers are you using?

Eric

[HS93]

Thanks for that , I looked at what othere people had done and took the bits I liked, the problem was trying to find a way to pre tensison the lead screws and fit handels. I made an adapter to fit on the gear that is then bolted to it.
the steppers where from Arceurotrade the full speck is on the site.

Peter


180Ncm - 1/4"  Shaft - Hybrid Stepper Motor

http://www.arceurotrade.co.uk/Catalogue/Stepper-Motors

[bogstandard]

Hi Peter,

I am glad you have made your way here. Welcome.

I think this is a place to show how well you have got on with your conversion, and it is coming along real well.

John

[CrewCab]

Welcome aboard Peter, looks like your conversion's coming along nicely, it certainly seems nice and smooth under power.

CC

[Chris_b]

A few notes about the electronics for Peter's mill conversion.

There's a driver box and a manual control box plus a 24 volt power supply.

The driver box (not in Peter's photos)  is basically a packaged up MD3AXSI8435N controller from www.mdfly.com which is intended to connect three steppers up to a PC running CNC software. He sells a few variations on the theme, and not all of them all the time. Eg the board above isn't on his site at this moment, but will probably return at some point. There's several other people who sell boards like this, which really just wire up three Toshiba 8435 driver chips which do all the work, and usually add some optoisolators plus inputs for limit switches etc. There's a 25 way D connector and a cable to connect to a PC parallel port. Mods I did to this board include:

- fit a decent size heatsink and a fan on the outside of the box
- replace some of the ic's Mdfly decided not to fit, mostly optoisolators but also a voltage regulator
- change a diode in the power feed which wasn't properly rated
- fit some pullup resistors so the unit sits in a guaranteed safe state if you pull the D-type plug out/power it up without the PC connected

The manual control box replaces the PC and is homebrewed to Peter's requirements.

- a 100-step rotary wheel which can drive X or Y axes. With Peter's 2:1 belt drive, 2mm pitch lead screws on the mill and the right settings in the driver box (half-step I think) you end up with one rev of the wheel = 1mm table movement
- alternative to the rotary wheel, buttons for +/- X and Y movement (speed variable)

- buttons for Z movement

- a few switches to select the above, and some lights to show what's going on

- a big button for the spindle motor (see below)

Mostly on account of the rotary wheel, the manual control box contains a microprocessor (PICAXE 28X1 - see www.picaxe.com) and about 15 ic's. The circuit is not optimum and there could have been less ics if I'd not used the Picaxe which contains a Basic interpreter and is thus slow enough that I had to do some functions in hardware that could have been done in software.

If you don't require a rotary wheel, it could be done with a few ics and I'm currently (err rather slowly) building one of these for myself. Incidentally this will run a different driver board to the Mdfly one as he stopped selling them for a bit. As all the stepper control work is done in the Toshiba 8435 chip that's not a problem.

I've reverse-engineered most of the X1 control box (nb for MY model, I'm sure there are several variations) so I have some inkling of how it works, including the zero-volt safety feature which is particularly devious.


If anyone is interested I'm happy to let them have the circuits and software for the Picaxe which I'd release under the Gnu Public licence ("once free always free"). I'd post it all them on a website but I don't have one (=too lazy to set one up and look after it).

I've got some photos of the innards somewhere which I'll post when I've found some which don't demonstrate my chassis bashing skills too vividly (Peter has been *most* polite about this  )

Chris

[sbwhart]

Wow great job   

Have fun
 

Stew

[Chris_b]

Here's a couple of pics. I've added some explanation for those who aren't too familiar with electronics.

The first is the Mdfly driver board being built into its box. Things to note:

- More heatsink. The black one is bolted to the original silver one with a very thin film of heatsink compound between. The fan sucks air through the box from R to L. The inlet grill got a piece of loose weave filter gauze added later. Without extra heatsink and fan the driver chips would likely get too hot in this situation.

- The actual driver chips themselves are mostly hidden from view you can just see their legs to the left of the three capacitors in the big round cans

- most of the ics on the board don't do anything tricky. The little ones with 4 legs (black and white) are opto-isolators. When I received the board, they had been replaced by wire links (shows how important they were considered to be!). I happened to have some lying around so I fitted them. The general idea of optoisolators in stepper drivers is to protect the driver chips from any voltage "surprises" coming into the driver on the 25 way connector, and vice versa if there's a fault and the 24 volt stepper mtotr power gets fed back to the PC. The 20 pin ics on the left by the D type connector (you can see one and a half of them) will probably do as good a job of protection by acting as fuses!

- the 16 pin ics on the right of the picture drive some LEDs on the board to show when step pulses are being applied. The circuit is wrong and the LEDs don't work as intended so I ignored them!

- the red switches in the middle of the picture set the step mode for the three motors. This basically translates into how many pulses have to arrive at the connector to make the motors move one full step

[Chris_b]

Here's the second set of pictures - of the manual controller box, and the circuit board which is the heart of the controller, . Not much explanation that's worthwhile, except to say there's more ics than strictly necessary as I chose to keep the circuits that look after the push buttons completely separate from the ones that look after the wheel. This means a lot more wiring up, and the circuit board is an old rapid prototyping board I happened to have from 10+ years ago. These are now unobtainable and were very expensive in their day so I can't recommend that as a way of duplicating the unit. the bottom view shows the volume of wiring.

(looks like this will take 3 posts due to the attachment size limit)



I'll add some more remarks about duplicating the above in the next post - it doesn't have to be this hard!!

Chris

[Chris_b]

Circuit board - top

[Chris_b]

Circuit board - bottom showing the rat's nest!

[Divided he ad]

Sometimes I'm glad I didn't go into the electronics!!!!!! 

There's a lot of stuff in there Chris!!... Your a lucky man Peter to know someone who understands that lot!!


Chris, just a note, if you take a look at the post about pic's You might find it easier in the long run?

http://madmodder.net/index.php?board=11.0

It will save you having issues with the upload limit 


I know Bog's has a slightly    question about LED's too.... If he's not too quick to ask then I will as I want to know the answer too! 

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For future reference, how would I go about making a lighting block that only lit the lights as the votage got higher. So say the first one came on at say 6v, the second at 8v etc, and when it reached say a max of 20v sound a buzzer that will warn me to start slowing it down.

Wiggly amps and electric string are not my strong points, I basically understand things, so please, no words longer than three syllables.

Bogs
 
 

I want to make a similar item.... Sorry if this is an    hijack Peter.... If you have an answer to this Chris could you post it in the 'Gallery' under "my turbines" Thank you.




Ralph.