Getting organized before printing parts

Mostly Printed CNC - MPCNC Advice
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I’m planning to start printing parts on Monday for my MPCNC.
while those are printing I have a number of things I want to start looking into and figuring out as much as I can before I finish the build.

So…here goes.
1 - Wiring. I found the wiring page and looks pretty clear. Are there any good youtube vids that clearly walk through this? Most of the videos simply show that stage of build, but not a clear and concise “this wire plugs in here” sort of thing.

2 - I’m planning to use fusion 360 for tool pathing and the G-code. I found Guffy’s post processor for fusion (https://github.com/guffy1234/mpcnc_posts_processor)
is that still the best one?

I’m planning to do 2 sided 3D milling (cutting model rc airplanes). Will fusion and Guffy’s Post processor work?

3 - I read a post that the post processor for fusion requires a LCD. Will the $14.00 version from V1 work?

4 - Determine final Z height. Some of you may have read my post on purchasing either the Mpcnc or low rider. (I have chosen the MPCNC, mainly for cost).

I need to determine the overall length of tube and lead screw for the Z axis. The calculator, I assume, probably takes into account a typical shorter end mill, but I will need a longer end mill for the tasks I am doing.

I am planning that my largest cut size will be 4 inches. this means I will need about a 5" - maybe even 6" end mill (allows good clamping in the collet plus a little extra for the head to clear the material.) Plus what ever the machine needs to mount in the printed parts.

would it be easiest to take the calculator and add 4" for material and 4.5" for the length of the end mill?

5 - End stop. since I will be doing two sided milling and the milling time will probably quite long I will need the end stop. (I will practice with the basic set up and 2D - baby steps - before I get too far with using end stops) do the end stop come with the dual firmware and wire kit, or do I need to add those to the purchase?

6 - Are there any good videos out there on how to use the end stop? Pausing a project etc.

That’s it for now. I’m sure I will have more.

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Here’s a first run at some answers, I hope some are correct…

1: None that I know of. It’s not that hard, just slow down a little and make sure you know what you have in your hand before you just jam it on some pins.

2: IIRC, it’s the best for Fusion360. The general consensus is to use EstleCAM first before dealing with the complexities of Fusion360 CAM.

3: Not necessarily… You’ll need to have something hooked up. Either a computer with a gcode sender (RepetierHost, CNC.js, bCNC, whatever), or an LCD with an SDCard reader.

4: With that sort of bit length, you’re going to have some serious runout, and a lot of flex in your cutting edge. It can be done, just be aware that you’ll need (multiple?) finishing passes, and some adaptive milling, and you’ll probably never be able to mill any metal. But to answer your question, I don’t think you need to add anything. Just tell it what your desired Z travel is, and it should work out.

5: Milling time has little to do with endstops. Because you’re not going to leave your machine alone while it’s running. Assuming you’re talking about pausing your job, and re-homing to continue, it’s not that critical. People have been homing their MPCNCs without endstops for generations… :wink: And it makes things a bit more complex (especially the wiring).

6: Dunno. But I’m sure it’s been/being done.

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1 - OK, I figure it is pretty straight forward. if there are questions I will post before plugging things in.
2 - Forgive me, but what is IIRC - a bit new to this.
3 - OK
4 - Yeah, bit length does add some complexity. I’m planning to only cut xps foam at that size.
5 - the only reason I bring up end stops with milling is because of the time it will take to cut a project. I won’t leave it alone, but it will take more than one evening, plus needing to flip the part for B side cut. From my understanding this is where end stops help. Allows to pause, change bits if necessary, flip parts etc. Or are there ways to do this without them and how easy is that? - Edit I realized I didn’t read your full comment on #5. I’ll think of doing it without end stop. Any good resource on pausing and restarting without endstop? I’ll look too, but if you have a good place to look…
6 - I’ll keep looking. Maybe I end up being the one to make the video.

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2 - IIRC: If I Remember Correctly

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1 - I don’t know that there are any youtube vids that walk through this, but it’s pretty simple. The twho things I would recommend is line everything up and tape them together as you straighten. It makes life easier if you are going to use wire sleeve to organize, and if you plan to use the tape measure trick, I’d say almost absolutely necessary (see my new build in tampa thread to see what I did to make it easier). And also LABEL the wires as you connect them so you know which wire is which at the end.
The most complicated part of the wiring is literally at the end when you plug into the Rambo board and that you just look at the diagram of the Rambo and plug the X1 stepper into the X1 slot. If it’s turning the wrong way when you test it, flip the connector.

5 - I can’t answer how an end stop may or may not be used for doing 2 sided milling (I’m pretty new to all this) I did get the dual endstop kit from Ryan and it came with the end stop switches. You will also have to select the wiring at the time of the order for the dual end stop. I will recommend, if you go this route, make sure you leave plenty of wire for the end stops when wiring. I thought I left enough then I had to make 3 inch extensions.

6 - if you find one, let me know! :+1:

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@kvcummins hah :slight_smile: There’s my age… and I’m not that old.
I was thinking IIRC was some form of post processor.

@louspinuso Thanks for the feedback. I’ll check out your post this weekend

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So a buddy of mine has a 6" end mill and I will be getting the DW660 soon. We can test just how much flex and wobble there will be.

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4- If you’re doing foam, then a huge Z and bit are ok. If you ever want to cut some wood, you can get some rigidity back by putting a bunch of wood under your workpiece (to bring it close to the gantry) and using a regular sized bit.

3- The Ryan LCD is the LCD on the forums. It will help you with the fusion PP if it puts any pauses in the gcode, which it does with sone settings and the tool changes. Estlcam is much easier, BTW. Even if you still use fusion for CAD.

5/6- While the machine is on, the two X motors are moving in lockstep. They move exactly the same distance on either side. If they start square, then they will stay square. Dual endstops allows the firmware to move the axis to one end, and measure the distance for each motor before it is square. After it homes, they move in lockstep again. In the years of MPCNC before dual endstops, what we did was just hold the gantry square when we started it up. The hackiest way to do this is just to use the tap measure and nudge it square. The more reliable way is to put sone clamps or print some spacers at the Xmin and Ymin positions and just pull the gantry up against the hard stops while enabling the motors. The next day, you can do the same thing and get it the same squareness.

The other half of the problem is. When you’re starting your work, you have to jog the machine to the origin and reset the origin (Tell the machine that THIS is now 0,0). Before you do that, write down the coordinates so you can move the exact same distance from Xmin and Ymin before setting the origin for the second cut.

When you are doing dual sided work, you will probably want to just set up one gcode file for one side, and the other side in another gcode file.

Some Old Guy Coding has some videos on tool changes and double sided milling. They were made before dual endstops.

This will all make a lot more sense after you have done a few jobs.

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That is so true. It took me a little reconfiguring to get my origin correct in relation to the axes, gantry and how I arranged the wires. You know that video from Some Old Guy Coding where he shows how to to loop the belt for the ZenXY? That type of illustration for routing the wires through the conduit would be helpful. Something I’ve thought about. You might want to draw out a block diagram that includes the motors, the conduit, the sides of the machine and where your controller is going to end up. then draw out the wires as the go from the motors, through the tubes and sleeves along the sides and then finally connect to the control board.

The LCD connectors can throw folks, as it did me first. Endstops are another complication. Then there are different boards in play so sifting through the different examples can be tricky. I should have printed out several copies of the board as a reference. I kept going back and forth from the reprap wiki illustrations for my Archim2 and the board I have trying to figure out orientations and what went where.

Had the worst trouble jamming the power wires into the small connectors.

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Sorry for the delayed reply. Thanks to those who have responded.

Yup. I’m actually looking at building a table where the MPCNC is up on blocks for tall parts and then can be lowered when doing wood etc. Though it might be easier to keep the MPCNC where it is and build a platform that can slide under it…

So when the machine is off the steppers are free to move - correct?

So simply check for square, then clamp the the moving rails before turning on?
Using spacers is a good idea. keeps it the same each time.

Can the touch plate, sold on the side, that is used to set the Z axis be used to set the x and y? Seems like it should.

I was even thinking of setting up seperate G codes for different lengths of tools. start off short and switch to a longer mill as I go.

@scrounge79
I’m thinking I will actually go through setting up all of the electronics before assembling and labeling things before too.

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Correct.

Yeah, I used spacers on my mpcnc and I use the end of the table for the LR. The zip tie holders can also be used on the LR.

No, marlin doesn’t support that.

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OK, so I’ve been printing the 23.5mm version of parts and my tubing is very tight fitting. The Z_Lower_C_Burly will be a challenge to fit on the tube - to be honest, I feel I would need to sand it out a bit.

I checked the lock corners too and those are also really tight.

I re-measured my tubing and it is 23.6.

I feel like I would need to hammer some of the parts on, which I don’t think is the idea.
I did do a print test at 100mm and all dims measured fine.

Will this be an issue? could this just be a tube out of tolerance?

Update, I just measured the Z_Lower_C_Burly part that I just printed. It is measuring at 22.4mm dia.

Is there an easy way to sand that out a bit.

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Is it consistently that diameter, or only one one side? I find that I have to sand off the elephant squish on my first layers fairly often if I’m working with tight tolerances.

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yeah, it is consistent between the two.

I was able to pry the hole wider and slide it. Not sure if this will cause issues in the future though.

image
image.jpg642×580 113 KB

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So a buddy of mine, who has some experience with printing, suggested using a small flap wheel sander with a couple quick passes. Should clear it out enough. I think I will give that a try.

will let you know how it works.

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That is pretty far off, the ones I ship are showing 23.1-.2. You said a cube came out okay, print a large test piece there are several 100mm versions, that will show real issues and also you need to check all six diagonals to make sure your printer is square. That is the one no ever checks and the one that is most commonly bad.

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Thanks Ryan
I’ll test again. What is the recommended settings for a test cube? Fill, walls etc?.

Based on the measurements I have will I need to reprint it or do you think I can get by? I’m about half done. Haven’t done the big parts yet.

I can get a list of what is done tomorrow.

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I print my calibration cubes in vase mode.

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Look up a bigger test part the 10-20mm test cubes are very deceptive and easily hide errors large enough to be an issue. There are lots of 100mm test items.

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OK, So here are some measurements I got.

Unfortunately I did not get Z measurements. it started to separate from the build plate. I will try another one soon but thought I’d share these for now.

These don’t seem too bad right?
The diagonals are the farthest off.

image
The 00.6 measurement on the left should read 100.6. It got clipped when getting the screen shot.