Thread: It's begun....
You might want to look at www.ascmetals.com and remember that Aluminium can have both a crown and warp to the sheet. This means that unless you are buying engineering grade that you will most likely have to face the metal or have it faced to bring the surfaces into true parallel. Depending on how large the section of plate you are using this might have no effect, on the other hand the wider and long a plate is that has not been brought to tolerances the more likely the piece will have warp or crowning and that means surfacing/facing needed to be done to bring it into tolerances.
Just a few points that you might want to consider when looking at buying as the cost in material does have a bit of a reason behind it.
Link added to my list of suppliers.
The ali plate I have seems to be pretty accurate over the size I'm cutting it to, but I'm expecting some shimming being necessary, as my cutting of extrusion is likely not to the same tolerance. Hopefully I can get the machine true to itself to a certain degree and then work on replacement parts machined to better tolerances than the current tools I have been making it with, or of course issue some RFQs here for bits...
A quick update, as I got some time to work on the machine tonight, but no pics (will post some tomorrow):
I have my first ballscrew mounted, as I figured before I attach the Z-mounting plate the Y Axis needed to be finished. Used a Bosch 17mm bi-metal hole cutter to bore the holes in the gantry sides for the ballscrew and I find these tend to cut ~1mm over size (possibly due to my bench drill being a little wobbly). This is fine however as I need a little clearance to allow for alignment adjustment and have ~1mm rather than the intended 0.5mm.
The floating end is attached using an FK bearing block and circlip and the fixed is also a larger FK type which goes in the stepper motor mount and that is bolted to the gantry side also.
I have come across one of those annoying gotchas where the supplied ballnut mount protrudes ~1mm too far outside the gantry, so I need to work out whether I can "pocket" the ali plate for the z axis by 1mm using the tools I have. I'm thinking of very gently/slowly milling the pocket using my bench drill and an 8mm TC End Mill with the z axis plate clamped to my small cross slide table (normally only used for drilling holes in a straight line) - not sure I should mention a foolish move like this here, but it's a problem that needs solving (I have also toyed with using a low speed on my hand wood router, but I don't trust myself with that method.....).
Hopefully tomorrow I will also get try out the new circular saw on the ali plate (didn't finish work till late and the neighbours would probably not appreciate the tortured machining noises;-) ).
I must also try to resist connecting up the Y Axis just to get something moving under its own steam.....
Afternoon gents (and ladies),
Not posted for a little while but I have not been idle ;-)
Here are a few pics of latest progress and despite a few "rough" bits (z axis plates and spindle mounts), I am finally approaching the end of the mechanical side of things.
I do a have some deflection in the gantry, which is due to my crude mounting solution, but have an RFQ out to help resolve this and will soon order a second ballscrew plus pulley/belt to make sure both sides get equal x axis driving force.
In the meantime, I am now working on the cable runs for the steppers and then the water cooling system and VFD/spindle wiring.
Good news is I have the rest of the year off from work, so I'm hoping I can get at least some light material cutting underway before Christmas.
Lastly before finishing I had better relate some frustrations:
1. I had underestimated the weight of the gantry once all the "stuff" is on it and care is needed when assembling the z axis, as its easy to drop the spindle/mounts etc and if your fingers are in there pain can result - propping things up when securing bolts etc is a must
2. Constructing the z axis is a pain the first time you do it - everything had to go on in order to avoid not being able to get tools onto bolts/nuts etc.
3. Like a berk I assembled the gantry reversed as you can see in one pic, but luckily I needed to almost completley disassemble the gantry to get the y axis ballscrew mounting block in, so put it back the right way.
4. to align the x axis ballscrew I torqued down the fixed end (stepper motor end) then ran the gantry by hand to the far end and tied down the ballscrew and floating end bearing. Hopefully that is the correct method, but it turns and moves easily by hand (I'm assuming turning a stepper by hand is OK).
5. I had a job getting the rails into the bearing blocks on the z axis and actually stripped a bunch of ball bearings out of one of the block, so had to get some replacements, but they are relatively inexpensive and I've sorted out a method which involves only bolting one end of the rails to the front plate, which gives some play to allow for alignment. I then put the remaining bolts onto the rails once they are located in their bearing blocks - not a hard job just needs doing with the front plate in the right place, so I can get access from the rear.
Oh I should (fingers crossed) be moving house soon and I'm really looking forward to the new workshop :-)
Hopefully my next update will not be too far away.
Quick update and some questions someone maybe able to help with.
I have thrown an e-chain on for the x axis movement and wired up the 3 steppers with cables going back to my control box (shield connected at the control box end to my earth point and not at the machine end).
I figured I would get the stepper motors working first before moving to the spindle and VFD and to prepare for the first control box power up I have done the following:
- Manually moved the spindle to the centre of x, y and z travel so that if for some reason the machine decides to shoot to the extremes of my travel I have time to hit the estop.
- Loaded Mach3 and connected the PC I'm running that on to the ZP5A-INT controller board/BoB but not in the control box so I can set up the software according to this pdf manual without risk of the machine moving in an undesired fashion: http://www.zappautomation.co.uk/down...d%20manual.pdf
After running through that manual for setup I have loaded the Roadrunner.tap and run the GCode - the LEDs for the axis on the board are flickering nicely in sync with the movement on the Mach3 3D display, which is encouraging.
All good so far, but here comes the questions:
Having wired my steppers and drivers in bi-polar parallel mode (wiring diagram: http://www.zappautomation.co.uk/down...%20%281%29.pdf) I am now stuck with what dip switch settings to use on the drivers (PM752's - http://www.zappautomation.co.uk/down...vers/PM752.pdf) with the following Steppers: SY60STH88-3008B (Data sheet: http://www.zappautomation.co.uk/down...H86-3008BF.pdf)
My first guess is the following in order from SW1 to 8: OFF, ON, OFF, OFF, ON, ON, ON, ON which should translate to Peak Current 4.09A, RMS Current 3.32A, Standstill=Half Current, Microstep=4, Steps/rev=400 - I have no idea if this is correct although one of the manuals mentions setting the Amp rating to the closest for the motor and 4.09 seems to fit that bill.
Any help would be gratefully received before I wire the BoB back in and throw the switch just to see what happens :-)
Oh if it helps I have 1605 ballscrews on all axis.
Great Jonathan, I will throw the power switch tonight and all being well should get some movement out of the machine.......consider me excited now :-)
Quick update - powered up the control box and nothing has sparked or smoked, which is nice.
The steppers seem to have power to then as they are making a slight humming noise and the ballscrews are now solid (i.e. I can't hand turn them). However, I can't seem to get any movement from the jog control or up and down cursor keys in the motor tuning dialogue. Also I have green LEDs lit on the drivers, which I also consider a good sign.
I've probably missed something silly in Mach3 so will watch some more tutorials and see if anything jumps out at me.
Hmmm I think I am stuck now:
- I have checked my wiring several times (including continuity testing to make sure I haven't crossed any on the signal wires in error) and everything seems to check out.
- My drivers have their green lights lit.
- The breakout board seems to be responding on the axis correctly i.e. I use a jog key in Mach 3 or run the Roadrunner.tap GCode and the activity lights on the axis outputs seems to be lit when they should.
- I've tried the enables 1 to 3 ticked in the mach3 Outputs tab on Pin No.1 using Active Low ticked and unticked and using Pin 1 as suggested in the BoB instructions (when I have these checked the diagnostic screen in Mach3 is showing 3 red "LEDs" for each
- Tried 25000 and 35000 Kernel speeds (35000 is the setting suggested in the instructions)
- Checked to make sure the parallel Port's address is correct
- Checked and re-entered the Motor profiles for each axis as per the BoB manual, although I notice my G's value doesn't match theirs
Anyway all of that and each time I switch the machine on the steppers lock in place with a kind of high pitch hum and refuse to move, as if there is constant power going to them but no direction.
If anyone has any suggestions I'd be grateful , as I think I'm either missing something very fundamental, got some defective parts or some arcane setting in Mach3 is eluding me and I'm running out of things to try.
Having slept on the problem of my stuck machine can someone with wiring knowledge check a theory I have:
I've been wiring up according to this diagram on the Zapp website: http://www.zappautomation.co.uk/down...%20%281%29.pdf
Looking at it and taking the x axis as an example, the wiring diagram shows all the +ve connectors for Pulse, Direction and Enable wired together and going back to XN (which I am assuming is X -ve?). Shouldn't this be the other way round i.e. the Pul-, Dir- and Ena- should be wired to XN?
If so I can re-wire and try, but some wiser head than mine with a view would be appreciated.
Thanks in advance.
BUILD LOG: Web Goblin cnc has begunBy Web Goblin in forum DIY Router Build LogsReplies: 147Last Post: 12-02-2012, 07:49 PM