Wishing you quite a lot of luck, and once rebuilt, I think Allison will be way better than before. !
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Update:
It is DEFINITELY NOT PRETTY!!! But it allows for the adjustment that is required!
[attachment file=54785]
I carved out the motor mount plate to allow almost 2mm of adjustment on the motor positioning and with some fender washers, mounted the motor.
Of course the original cap screws were not long enough to get through a washer, a fender washer, the mount plate and then thread deep enough into the motor casing.
All I had was cap screws that were WAY too long - so a couple of nuts as extra spacers had to do.
Then I ran out of nuts AND washers - go figure!!!
I test fitted the Z axis guide shafts - did the “roll on a table” test - they as well as the lead screws were also nice and straight.
So I got the left side all sorted out but on the right side I had to relieve the motor mount plate even more… Which I did.
After making a cup of tea, as I walked back into the room I noticed from the angle I was looking at the machine that the lead screw was NO WHERE NEAR PARALLEL to the guide shaft!!!
While I had been sitting “up close and personal” working on her I had not noticed this.
Then when I loosened the first screw holding the nut to the printed part I noticed the nut lift ever so slightly away from the printed piece.
Grabbed a small straight-edge and had a look see and found that the area where the outer most mounting screw for the lead nut is was dropping away.
Now this surface is the one that is on the bed when the part was printed and “should” be perfectly flat and at 90 degrees to the axis of the guide shaft.
Obviously what must have happened is that this area had lost adhesion to the bed and lifted slightly which under other conditions would not have been too serious but in this case caused a major alignment issue because as you tighten down the lead screw nut, it gets forced out of alignment causing the issues being experienced.
So what to do about it?
[attachment file=54786]
Eventually I decided to NOT screw the nut tight onto the carrier but to leave a small gap and lock the nut with another nut so that nothing comes loose.
I repeated the process on the side with the fall-off, making sure that the lead screw was now parallel to the guide rod when the force was up the lead screw as it would be during operation.
And guess what? Now everything fitted nicely at the motor end of the lead screw as well.
(I remember correctly this is where I found the piece of match stick jammed in so “someone” had found this previously and done a “quick fix” which had not worked.)
The long and the short of it is that Alison is probably going to be printing herself a pair of new Z guide brackets in the near future - along with a good couple of other “bling” items like cable chains and other wire management goodies.
So basically I am stuck until I get some more cap screws of the right length. The only place you can get them from on a Sunday is RIDICULOUSLY expensive!!!
On my shopping spree last week I got a 100 meter roll of 1,5mm wire and a boatload of plugs so today its me and wired - heaven help us all…
Thanks for reading - and any advice would be appreciated.
Haha. I was going to suggest shimming it. Also grease up those screws a little. Are they moving smoothly up and down?
Hey Jeff - no motion yet.
Shorting a bunch of fasteners and every wire in her has been stripped out - ran out of cable wrapping too.
And was that ever a mess!!!
Anyway, laying new cables and wires where needed, routing the ones that I can keep properly.
All that sort of stuff going down at the moment but baby is getting a new party dress and she will be going to the prom hopefully before Wednesday.
I think that I will have to do the final setup as if it was out of the box because who knows what they “tweaked” to work around the mechanical issues.
I really wish I still had a dial gauge to measure the axis movements to get steps per mm right but I suppose a vernier will have to do.
Thanks for the interest and you have a good one…
You can tell just by twisting it by hand. In my experience the problem with this nuts not being perpendicular is that they really stick. If you cant turn them by hand, then thats a problem.
The parts are made very accurately and in metric sizes so you should be able to just calculate the steps/mm. Something like 200, 800, 160… They almost always line up with something like that (unless you have an imperial leadscrew, which I’m sure you don’t). Just a tape measure would be accurate enough, and just using one of the calculators is also fine.
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The exception to that is the extruder…
;>} Jeff, you do not know me very well YET!!! I’m kind of a major pain in the butt when it comes to setting up machines that I need to be pretty accurate…
Believe that if you take the time to dial everything in properly and make sure that everything is playing nicely with everything else then if you hit a problem it is normally far quicker to troubleshoot - and if there is no problem then it just sings along.
But of course everything has to be within reason as well.
I have a good smile when guys on the forums are discussing how to get their machines to within 0.01mm or better repeat-ability and then when you have a look at their machine its frame is chipboard or some similar material which changes dimension quite a bit based on the humidity.
And then you find out that they are machining WOOD!!!
Basically it is horses for courses ~ know the machine limitations and get the best results within those parameters.
I know that the MPCNC is pretty stable for what it is but I’m not naive enough to expect to build NASA or military spec components on it - that is definitely the way to go to get ulcers and migraines. I want to have fun with mine.
Enjoy whats left of your week end there buddy.
Well, actually in reality aside, the correct value should be something like 200.000, because there are exactly 200 steps per revolution and you are using exactly 1/32 microstepping and there are exactly 16 teeth per gear, etc. Thats why im saying the calculator is right. Any measurement you take will just add error.
The extruder is different, because its a hobbed gear gripping the plastic. The best you can get is close, with measurements.
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Come to think of it you are absolutely right there Jeff - thanks for bringing me back down to the planet ;<}
Would it not be nice though if there was some way of accurately measuring the volume of the extrude out of the nozzle without having to “guesstimate” the diameter of the filament?
If the machine could automatically compensate for variations in filament diameter of say 0.10 either way then we would all be extruding our own filament because the allowable tolerance would be so much bigger and therefor 1.75mm plus/minus 0.10mm is FAR easier to achieve at home than 1.75mm dead.
At one point in my life I was a production planner in a factory that molded all the bits for household appliances (irons, kettles, toasters etc) and there was a couple of the large nozzle bore machines that had a gate valve in the nozzle to prevent ooze when the nozzle was retracted from the die set - something like that would take care of stringing and the need for retraction but on this small scale that would probably be overkill. But it would be nice because there is no way that the slicer can take ooze into account which means that WHEN you get ooze (stringing) the first part of your next extrude WILL be under-weight.
But I suppose that if everything was an exact science then that would take the challenge out of 3D printing.
Sort of like having to tune a CNC mill to take into account tool deflection and bed flex based on the feed speed, tool, material being used and the capabilities of the machine.
But when you get all of THAT right you stand back and think to yourself “NAILED IT!!!”
Yeah, that would be nice. There are some “improvements” to Marlin and another firmware called “klipper” that tries to manage the floor by pressure in stead of position to get the right volume, but it’s not using feedback to determine the pressure. In my experience, the filament size has been pretty consistent.
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Update:
Hi All - been one of “those” weeks!!!
But Alison is together except for the extruder/slide assembly and the heated bed.
Here is a “before” of the rats nest of wires
[attachment file=55354]
And here is the “after”
[attachment file=55355]
It was a total mess - the loom had been hacked, a black wire goes into the spiral wrap that someone used to hide the bad choices in assemble and a dark purple one comes out.
The one Z axis motor has a green going in and it came out as red, the red came out as green.
What a mess.
Long story short, all my photos and wiring diagrams made before the tear down were…USELESS!!!
So all sorts of looking up on the site and here we are.
11pm local so I’m calling it a day - tomorrow she must move under her own power and then we start the final dial-in - think I should go through the software settings as well, set everything back to default and start from there.
Later everyone.
Progress!
The before picture looks a lot like everything I build. 
I know EXACTLY where you are coming from but I also know the pain that it causes!
It is not “right” yet, the wire pairs should be twisted to reduce electro-magnetic bleed because the fish tank air pipe that I had and which I used as individual wire management conduits will harden and become a lot less flexible in time but what can I do? It is what I have right now.
I will print up cable chains and mount points etc as soon as I can - and the Z axis blocks as the current ones are somewhat “crippled”.
I also noticed that there is not enough space on them for a “normal” sized micro switch and you have to use one of the very small (read “expensive” here in South Africa) variety so that needs to be addressed too.
But that is something for another day.
One good thing though is that she had proper straight and hardened multi-start lead screws and not M8 threaded bar - that stuff is NEVER straight and the tolerances and finish on them is crappy wherever you source it locally and if you import it you might as well get lead screw - suppliers just pack it better and some times it gets here and is still straight.
Wish I still had my lathe! Making up improved parts would be so much easier…
Here is the WhatsApp I just sent to a friend:
Took a deep breath, gulped down a BIG mouthful of tea, plugged her in and switched her on.... NOTHING!!! Oh $#!T.... Unplugged her, got out the tester, disconnected the main electronics board power wires and started going through everything... Then I saw that I had put the negative board feed wire into one of the positive terminals on the power supply. That right there is a sure fire way to blow the electronics!!! Under "normal" circumstances....Then I noticed that I had put the positive board feed wire into the next positive connector on the power supply. In other words the electronics board (which needs both positive AND negative to even think about working) only had one. Just maybe it was NOT blown.... So I put all the wires where they should be, checked every wire again, 100 times, and switched on again. Did you know that Alison has blue eyes? The blue power light on the electronics board started winking at me.... Plugged the laptop in and connected the software and tested the 3 directional motor sets. ALL WORKING !!!! So now I need to finish assembly and set everything up as it should be ~ happy days... Thanks for being so supportive - means SO MUCH!!!
And thanks to everyone here on the v1engineering community as well.
Love Alison’s blue eyes 
And please know you have supporters all around the world.
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Thanks for that - I will be needing those people when I try to get the LCD working - its probably a miss-match for the board but anyway…
My melzi is connected to a reprap full discount display. Should be compatible, although I had to make/edit the cable. I can see if I have my notes on it. I also had to edit the firmware…
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Would be helpful although it is probably C and I have not worked in C since the early 90’s - but program languages are like falling of a bicycle - easy to do and hurts like heck sometimes ;>}
Configuring Marlin doesn’t require writing software, it’s all configured by #define’s.
[attachment file=55670]
That’s my chicken scratches there. Not terribly helpful, but I think the lower left one translates from the melzi pins to the function to the reprap pins. I can find the pins file I used later, if you want it. It might be easier to follow the instructions from someone who has the same printer as you. My melzi board is not 100% standard (its from a wanhao).
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Jeff - you are a star!!!
I will definitely be pushing on your button when I get to that stage.
Aubrey