The Gantry is attached!

Now the fourth axis finally looks at home on the CNC plate.  The new gantry sides are almost 100mm taller than the old ones and share a similar shape. While the gantry was off the machine was a good time to attach the new Z-Axis which gains a similar amount of Z travel. Final adjustment of where the spindle sits in its holder are still needed but it makes sense for the cutting edge to be fairly high up when the Z-Axis is fully retracted as shown.

After a day of great success early on a day of great problem solving arrived before the attachment was possible. The day of great success involved testing the two new sides to see if or how well they attached to the mount points at the base of the machine. These holes in the gantry were hand marked, drilled, and tapped so there was some good chance that they were off target enough to not work well. But those all went fine.

The second success was mounting the Z-Axis to the existing points on the gantry. I had in the back of my mind the thought that one side (the three holes on the bottom of the mount) to line up and attach fine but the top holes to be out of alignment. Both of these plates, seen in horizontal in the image above, were made by CNC so the holes should be where I intended. Though these plates were both mounted to the Z-Axis and the bottom plate goes right through to the lower steel bracket so the alignment might not have been 100%. I registered both plates to the smooth side of the spindle backing plate so the alignment in that axis should have been ok. To great surprise and joy the top holes also aligned perfectly and the second phase fell into place.

It was only when putting the new sides onto the gantry that interesting things started to happen. I will have a new blog post on that part soon and likely a video of the problems and solutions for that part. One thing I will say now is that it helps to have washers, bolts, and spare skate bearings on hand for this process depending on how you have designed your far side gantry upright.

Waiting for the other Gantry to drop

When cutting the first side of the gantry I used the "traditional" hold down method of clamps and the like on the edges. That works ok when you have a much larger piece of alloy than the part you are cutting. In this case there isn't much spare in the height axis (left right as shown) and as you can see very little in the x axis (up/down in the below image). My clamping allowed for more vibration on the first cutting than I like so I changed how I went about the second side of the gantry.

For the second gantry, after flipping things in the software so that I was coming in from the other side I drilled out 4 m6 holes and countersank them.

This way the bolts (m6x40) were almost flush with the work piece. These bolts go straight through the plywood and connect with t-slot nuts in the alloy bed of the cnc. So there isn't much ability to use bolts that are too long for this application. Counter sinking the bolts helps on a machine with limited Z travel as using some non stubby drill bits really locks down the amount of free play and clearance you can get. The downside of this work holding is that you are left with 4 m6 holes that don't really need to be in the final product.

In this case it doesn't matter as I can use them and a new plate to mount one or two cameras on the back gantry facing forwards. I have found that the best vantage for CNC viewing is when not in the same room and looking at the video streams.

In future jobs I might move the countersunk bolts to the edge so they are not on the final work piece.

So now all I have to do is free this piece from the waste, tap a bunch of m5 holes, drill and tap 5 holes on 3 sides of the new gantry pieces and I'm getting close to loading it on.

Printer bracket fix

Similar to many 3d printer designs, many of the parts on this 3d printer are plastic. Where the Z-Axis meets the Y-Axis is held in place by two top brackets (near the gear on the stepper is a bolt to the z alloy extrusion) and the bottom bracket. One flaw here is that there are no bolts to the z-axis on the bottom bracket. It was also cracked in two places so the structural support was low and the x-axis would droop over time. Not so handy.

The plastic is about 12mm thick and smells like a 2.5D job done by a 3d printer 'just because'.  So a quick tinker in Fusion 360 and the 1/2 inch thick flatland part was born. After removing the hold down tabs and flapping the remains away 3 M6 bolt holds were hand drilled. Notice the subtle shift on the inside of the part where the extrusion and stepper motor differ in size.

It was quicker to just do that rather than try to remount and register on the cnc and it might not have even worked with the limited z range of the machine.


The below image only has two of the three bolts in place. With the addition of the new bolt heading into the z axis the rigidity of the machine went right up. The shaft that the z axis is mounted onto goes into the 12mm empty hole in the part.

This does open up the mental thoughts of how many other parts would be better served by not being made out of plastic.

Keeping an eye on it

The CNC enclosure now sports a few cameras so I can keep an eye on things from anywhere. The small "endocam" mounting worked out particularly well. The small bracket was created using 2mm alloy, jigsawed, flapped, drilled and mounted fairly quick. These copper coated saddle clamps also add a look good factor to the whole build.

A huge plus side is that I now also have a good base to bolt the mist unit onto. It is tempting to redesign the camera mounting bracket in Fusion and CNC a new one in 6mm alloy but there's no real need for this purpose. Shortest effective path to working solution and all that.

3040 spindle upgrade: the one day crossover plate

Shown below is the spindle that came with my 3040 "engraving" cnc next to the 2.2kw water cooled monster that I am upgrading to. See my previous blog post for videos of the electronics and spindle test on the bench.

The crossover plate which I thought was going to be the most difficult part was completed in a day. I had some high torsion M6 nuts floating around with one additional great feature, the bolt head is nut shaped giving a low clearance compared to some bolts like socket heads. The crossover is shown from the top in the below image. I first cut down the original spindle mount and sanded it flat to make the "bearing mount" as I called it. Then the crossover attaches to that and the spindle mount attaches to the crossover.

Notice the bolts coming through to the bearing mount. The low profile bolt head just fits on each side of the round 80mm diameter spindle mount. I did have to do a little dremeling out of the bearing mount to fit the nuts on the other side. This was a trade off, I wanted those bolts as far out from the centre line as possible to maximize the possibility that the spindle mount would bolt on flat without interfering with the bolts that attach the crossover to the bearing mount.

A more side profile is shown below. The threaded rod is missing for the z-axis in the picture. It is just a test fit. I may end up putting the spindle in and doing some "dry runs" to make sure that the steppers are happy to move the right distances with the additional weight of the spindle. I did a test run on the z-axis before I started, just resting the spindle on the old spindle and moving the z up and down.

I need to drop out a cabinet of sorts for the cnc before getting into cutting alloy. The last thing I want is alloy chips and drill spirals floating around on the floor and getting trecked into other rooms.

3040 for alloy

I have finally fired up a 2.4kw 24,000 rpm spindle on the test bench. This has water cooling and is VFD controlled. The spindle runs on 3 phase AC power.



One thing that is not mentioned much is that the spindle itself and bracket runs to around 6-7kg. Below is the spindle hitting 24,000 rpm for the first time.


With this and some other bits a 3040 should be able to machine alloy.