Step 22: 4th Axis (design)

posted in: Construction CNC DIY | 0

I’ve always been sticking around to build me one day a fourth axis, in order to cover more types of machining operations, and expand my repertoire. In fact, that has always been my intention since I buy electronics. There was only about 30 € difference between buying a kit of 3 motors and one of 4.La decision was clear, right?

Few days ago, gossiping online, saw some pages of people who had made a 4th axis based mdf panels in the same way I had mounted my router, and the truth, I did not find anything complicated. In fact riding a simple structure and a support shaft with bearings and a counterpoint, I would have done.

The concept of the 4th axis, basically consists of the following:

It consists of two aligned structures. One of these supports a shaft on two bearings, embedded in the structure. This shaft has a platform where the integral part is screwed. At the other end, there should be a crown wheel was connected with the stepper motor. For the transmission system, it is easier to mount a timing belt, it is something that I have not yet defined. The motor must be bolted to the first structure, and must have a system for belt tension, a bearing that can swing for example, to adjust the degree of stress.

The other structure, basically be a simple copy of the first, it does not need any type of transmission, it does not have to move. One has to support a counterpoint, which is basically a pointed shaft. This axis, interests that may be moved forward and back, to hold any piece sticking tip on this material. In the same way as in a lathe. No need to rotate the tip, it does not have to rotate at high speeds, their only function is to hold the piece in place and allow the rotation. To get the axial adjustment going from a M12 threaded rod, so that when in its position, can fix it with a locknut.

With all these concepts, it’s time to start designing.

Maybe what I see more complicated at first sight is basically the metal part: Axis, platform, counterpoint and transmission. The rest with the CNC machining can himself all the necessary parts.

Take advantage of a visit to the workshop to machine a shaft and the platform, and get a proper threaded rod.

Here is the result. The shaft is not very good finishes, but the pieces are perfectly functional. The platform has not yet made ??the holes to attach the pieces with flanges, but it’s something I can do from home quietly.





The transmission, I’m still looking for her. I’m still tracking some websites and ebay, when I find the perfect solution it will hang on the next post.

I have already started the design, and start having good looking:

What I need is a good shaft. where seat the bearings, and which couple the ring gear.

4o eje 02

4o eje 03

4o eje 04

4o eje 01

4o eje 05

In this design you can already see how I’m going to build. Now I only get the rest of components, design and finish. Of course, then we will have to do with the electronic connections, configure the LinuxCNC, and what it will cost me more surely learning to program the CAM so that it can be machined with 4 axles … promises to be entertaining.

Continue with Step 23: 4th Axis (Metallic Parts)