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The Meticulous Z-Axis


#261

i see there is a design with “new clamps” is there a new file uploaded outside the community garden? the file that i downloaded does not show these clamps in it.

also i downloaded the large master file from the community garden however when i upload the .nc file into ground control it does not import to scale. i cut the entire file out but it made everything much larger than it should be. closer to a 22" sled than an 18"… unless this is correct and i didn’t read it. there are 260 posts in this thread so forgive me if i missed it.


#262

Sorry guys, missed a couple of comments here, will do my best to answer them now.

I’m not sure, but my theory was that the Maslow has low side-load for a CNC router given the typical 1/4" step-down and the low feed rate. I do plan on putting this design through its paces to find out if the guides will deflect from the side-load, but I need time to get back to working on my machine. I have a couple 1/2" bits I’d like to try and do full-depth cuts, so I’ll really get a chance to stress test the design. If the rods are in fact too flimsy for our applications, I plan on upgrading to these:

They’re more like what a gantry-style machine would use, although they up the cost. I was trying to make this as cost-effective as possible.

I feel ya, relying on the Rigid router base can be incredibly frustrating.

I’d love to see that massive axis slide set up! That would certainly solve the above deflection worries. :wink:

The one thing I’d want to look at is the location of the spindle on that. If you cut the DXF as is, the spindle could be either to high or to low, in the Y direction on the machine. That could result in a significant loss in accuracy. In the current design, the spindle centerline is 118.11mm to the face of the spine, where the slide would mount to. If the difference isn’t too much, you can probably compensate for it with the spindle clamps. If you’re familiar with Fusion, you can download the model I made, and add in your axis to see what changes you will need to make to get it to the right spot.

The DXF file with these clamps is in the community garden folder. They are in 2D CAD Files/Prototype Sled Nested V2.dxf. See the below image for location inside the CAD:

That sounds like it could be a scaling issue, but it’s really hard to say without being at your machine. The sled in this design is 500mm (19.685 in) to make room for the gussets. What you got is 112 % larger than the correct size, which means that the plywood won’t fit in the slots correctly. I can’t remember if ground Control can scale G-code or not. Couple of ways (I think) this could happen. First would be calibration, where it would be distorted in the X and Y dimensions. The other would be using a different tool than I programmed it with, which is a 1/4" bit. The latter I think would be less likely, because you wouldn’t be that far off.


#263

Thanks for the tip, @MeticulousMaynard. I was planning to do just that with the y-axis. The rail is 1.66" back to front, so I’ll compensate by making the clamps a little thicker.


#264

Thanks for the reply. The side load may not be that high, however, in my mind it would be magnified but the weight of the gantry and router. Maybe I am thinking about this incorrectly. The MGN linear rails are nice but I have had some hit or miss experience with them. The cheaper ones seem to “stick” in place. By that, I mean it takes a bit of force to get them moving but once they do then they go smooth. For 3d printers, this initial jerking motion of getting the rail slide moving caused some bad layer alignment issues. I don’t think you would see that problem here. Any linear guide (like the MGN or the rod type linear rails) is at the mercy of the flatness of the wood. In the case of the Meticulous Z axis design, if the wood isn’t flat then the rail that is bolted to it will not be straight.

I decided to go with a C-Beam setup. I have seen some other CNC machines use C-Beams as well. Waiting for it to come in the mail. I planned on 3d printing the mount for the beam along with making alignment pins that would precisely align the mount to the sled. I was also going to 3d print the router mounts as well. The Maslow is not a high precision machine but I figure anything I can do to help it would be good.


#265

According to the online Fusion 360 model, the distance from the front of the z-axis spline to the front of the z-axis carriage is 2 inches. As long as that matches the DXF file, I’m good. Since my rail is 1.66 inches thick, I’ll need to make the clamps 2.00-1.66 = 0.34 inches longer (assuming the clamps are right against the z-axis carriage on my rail).


#266

When I did the math, I got .249". I prefer to work from the distance from the spindle centerline to the spine myself. This is mostly because it’s the distance we will want to end up with in your design. Both our methods are valid, and entirely a personal preference.

The spine is 4.6654" (118.5mm) from the spindle centerline, which is actually 0.39mm off from what I had previously started. That’s because that’s the clearance factor I add into my models so that the plywood tabs fit into the slots in the base.

In order to determine how much the clamps will need to be elongated, I also took the measurement from the carriage face to spindle centerline, 2.756" (70mm).

To get the spindle clamp height, we would want to subtract the height of your carraige assembly (1.66") from the distance from the spindle centerline to the Z-axis spine (4.6654").

  • 4.6654 - 1.66 = 3.0054"

To make the clamps the right offset, we would need to take their current size from the required size:

  • 3.0054 - 2.756 = 0.2494"

So you would need to offset that back line 0.2494" to get it right on centerline.


#267

Thank you! I’m glad I said something. I see now that I made mistakes taking these measurements.


#268

Not a problem, I’m always happy to help. :slight_smile:


#269

X7JAY7X —

Have you been able to get your C beam in? I am curious because I have one and have spent months working on dust collection for the C beam and I think I might finally be close! I had to take some design ideas of my own and combine them with the meticulous chute and it seems to be operating well. I hope to have pictures of it soon. But I would love to see pictures of your setup when you get it done.


#270

I have not received it yet. Hoping any day now. I had some ideas for the chute but haven’t started designing yet. I would definitely like to see your pics and design. Are you sharing design files?


#271

I can absolutely share what I have! Just know it is still a work in progress, however it seems to be working for me. Tomorrow I will see if I can’t get some stuff uploaded. I may put it on the thread I already have about my Z axis as to not hijack this one. If I do that I will mention you.


#272

I cut the sled with the MeticulousSled_0250-1FL.nc file. What’s the best way to get the alignment holes, or screw holes for the ring system on there in the right places?


#273

I just checked the files, the holes for the ring system are not in any of the G-Code that I have put in the Community Garden. Here I merged the code between the predrill and 0250-1FL files to see where all the holes would end up.

This is proving to be a little problematic to determine the best way to add those holes to the part. I was able to find the file I had used to make the nc files in the Garden, but I had to dig through the previous versions of my nest file to get it. I added in the ring system holes, since the model is old enough that it predated me adding the system in. The only weirdness about doing it this way is that the holes are blind, and are drilled from the side with the counterbores, which would typically be facing down. However, all the counterbores are for the linkage systems, so they will not be needed if you’re making your sled with the ring system, so it shouldn’t be an actual problem.

This is the updated, nested model of the sled:

https://a360.co/2TBJ971

I also took a moment and made up a drill program for the ring system holes using the same origin as the nc file with the 1/4" end mill, so you can just run that using your same setup. I don’t have the Maslow post on my work computer, so I posted it using the GRBL post. Should still work fine for drilling.

MeticulousSled_RingHoles.nc (917 Bytes)


#274

@MeticulousMaynard You are a mensch, thank you!


#275

Just an update on this: I decided not to go with this rail because I didn’t want to figure out all the engineering on my own. I’m going to use the parts spec’d out in the BOM.


#276

Hey all, I just got all the wood parts cut for this new Z axis and I want to thank MeticulousMaynard and everyone else that has helped with this design. I am excited to get it together but I do have a few questions.

I can not seem to find any specific information as to the locations of all the mounts for the rails and lead screw brackets. Is this not critical? It looks as if the rail brackets are mounted right up to the edges of the vertical spine and the lead screw is right down the center.

Is there a way to calculate the z-axis pitch? I opted for 16 tooth and 24 tooth pulleys so that they could be purchased on Amazon.


#277

The location of those elements needs to be fairly accurate. I need to make more documentation on how to do that myself. You can use the Fusion 360 model to help determine their location. I will have to make up a drawing on that at some point.

When I was assembling the rail guides, I actually started by putting the rail guides on the Z-axis carriage plate. They should bolt on to the 4 outer corners of the plate so that they are parallel to the spindle. This is where the 3D printed designs are really nice, because they make that alignment easy. Once those guides are secured, you can attach the end anchor points to each end of the guide rods, and then position them on the spine. I drew the where the centerline of each of the rods on the spine’s face so I could line them up parallel to the direction of travel.

You will want to make sure you mount the guide rails in a way that you have a hard stop before the bottom of carriage can come in contact with the dust chute or interfere with the triangulation system. In the model, I show them mounted as far up as they can go, but you still may want to shorten the rods so that they don’t interfere with the chute, ring, or linkage systems.

The lead screw is also not documented very well. It does mount along the center of the carriage. I attached the brass nut to a short piece of 1 1/2" x 1 1/2" x 1/8" angle iron because I had the scrap lying around. There is a 3D printed version of this as well that would make this part easier. The bearings for the lead screw will need to be mounted down the center of the spine.

This has proved to be a little tricky in the past, and required some trial and error to get the value spot on. I dug this out of one of my earlier comments (waaay back) of how to calculate the pitch:

So in your case, you are using 16 and 24 tooth pulleys, you would have a ratio of 0.667. You want to start around -7.1438mm, and tell the axis to move in 1mm increments to see how accurate that pitch is. You may need to tweak it up or down until the movement matches the input.