[boydage]

Moving through the lifetime of diy cnc machining I guess I am like several others and progress further towards a commercial machine. And in all honesty the work progresses to points where we need to think about maximizing flow. I have a few cool projects going at mo.

I am at a stage of manufacturing multiple parts quite often. They are becoming more complex. Alloy. Often these parts will need flipping and turning several times. Ive built jigs and stands to make it easier. What I do find is the forces created are not very forgiving especially even when using endmills as small as 10mm let alone the larger ones.

I am leaning towards building a 4th axis but keep thinking about those lessons I have learned when something has moved in the vice. Not very often, but hey this has happened. Is it worth doing? Like, do I build something that weighs 50-60kg and bolt it to my table with m16 bolts? Using a decent size lathe chuck and a stepper to drive it the necessary rotations to give me that 45/90/180deg turn to continue machining the other sides? Or is it a lot of work and only really worth doing if I use it every day or week? Or do I not worry so much and decrease the endmill size when using a 4th axis. No experience with them. Have built a lot of gear though.

Using Fusion I would be confident the g-code is easy enough to flip the part once its setup with the proper wcs. Dunno. Anyone want to share their own experiences with a good solid 4th axis build? My initial thought was just to build a block to rotate in a vice. This seems like a good idea. B

[ardenum]

What kind of a machine did you make? router? vmc? picture?

[Jim Dawson]

A 4th axis is like toilet paper, it is better to have it and not need it than to need it and not have it. I built my 4th axis to do one job that needed a 4th axis to accomplish. Since then I use it maybe once a year for something. Was it worth spending the time to build it? Yes, because I needed it.

Mine started out life as a 6'' Vertex Super Spacer, and can be used horizontal or vertical. I have run parts on it as large as 28'' diameter. In the next week or so I'll be using it to machine a 20'' dia x 1'' thick aluminum pulley for a project.

If you are moving parts in the vice then you are doing something wrong.

[ardenum]

Vertex Super Spacer sounds like a good solution, you can machine a servo mount and replace the handwheel with it. Seems like the simplest solution.

[boydage]

Thanks guys. There are some good examples online and some that look not-so-good ah. I am taking from what I have read here, and seen online. The 4th axis for my purpose needs to be heavy, robust and strong enough to machine alloy without moving. And accurate in all ways. A good brake would be to advantage is it silly just to think of a hydraulic disc on the rear somewhere? Massive stopping power there. Geared down good and proper with a tight worm drive.

Ok I am not much of a picture person. Not because my workshop is always busy and slightly messy. Along with my machine. The box was amazing for the first month, until I decided to install spindle control, then air control, then new Nema 34s in the place of 23s and suddenly the box is looking crowded and unfinished. But this is what I am working with. Actually, yes, I am a little embarrassed opening my box for all to see. But, it works reliably.

Anyways....... If I add a 4th axis, I am going to now need to change to a smooth-stepper to control the additional axis am I correct in this? I am still using a cheap-as-chips Chinese BOB yep. And I control the Y/A axis, Z, X, and there are no output pins left. Umm am I correct? Ive been meaning to upgrade the BOB just you know, have been using the machine and well, procrastinating. I either build a new box (not desirable) or move the VFD outside to its own home.

Jim your statements were the most memorable. Most impact. I need to do this. Am I on a semi correct path with what I have described?

[ardenum]

Thanks guys. There are some good examples online and some that look not-so-good ah. I am taking from what I have read here, and seen online. The 4th axis for my purpose needs to be heavy, robust and strong enough to machine alloy without moving. And accurate in all ways. A good brake would be to advantage is it silly just to think of a hydraulic disc on the rear somewhere? Massive stopping power there. Geared down good and proper with a tight worm drive.

Ok I am not much of a picture person. Not because my workshop is always busy and slightly messy. Along with my machine. The box was amazing for the first month, until I decided to install spindle control, then air control, then new Nema 34s in the place of 23s and suddenly the box is looking crowded and unfinished. But this is what I am working with. Actually, yes, I am a little embarrassed opening my box for all to see. But, it works reliably.

Anyways....... If I add a 4th axis, I am going to now need to change to a smooth-stepper to control the additional axis am I correct in this? I am still using a cheap-as-chips Chinese BOB yep. And I control the Y/A axis, Z, X, and there are no output pins left. Umm am I correct? Ive been meaning to upgrade the BOB just you know, have been using the machine and well, procrastinating. I either build a new box (not desirable) or move the VFD outside to its own home.

Jim your statements were the most memorable. Most impact. I need to do this. Am I on a semi correct path with what I have described?

I don't know what your running but AXBB from uccnc supports up to 6 axes, 2 axes need configuring some pins in the software. Could be a cheap alternative.(https://www.cncdrive.com/downloads/AXBB_E_manual.pdf)

I've been trying to find native clamping units that machining centers use but can't find any, neither pneumatic or hydraulic...they usually are full circumference clamping type.

I don't know how much stiffness you realistically need though, do you plan on updating to linear rails anytime soon? With your rails and spindle I think the worm gear in the Vertex Super Spacer would provide enough resistance in indexing operations.

[Jim Dawson]

Your shop and panel look fine, I'm embarrassed about mine also. Most home shop panels start out pretty neat and clean, then comes the feature creep. You just stuff parts in where you can fit them. That looks like a very substantial machine. Yes, you are going to need to add an axis. I have my VFD mounted on the back of my machine in open air, but in a position to be protected from flying chips.

I chose the Vertex Super Spacer because I had one I wasn't using, and I picked it up in a trade, so I think I had about $70 into it. 90:1 worm drive, with adjustable engagement so it's possible to adjust to 0 backlash by over engaging the worm. Maybe not the best practice for long life, but it works. It also has a built in brake that I removed, but could have been operated by an air cylinder. I should have left it in there, I'll re-install it if I ever need to.



And with the NEMA 23 stepper motor installed. I left the original worm shaft intact so the handwheel can be put back on for manual operation if desired.
Rapid speed is around 6 RPM, no reason to go faster.



The belt drive. 2:1 reduction



I added ball thrust bearings to the worm system. The original wave washer ''thrust bearing'' proved not to be up to the task.



The drive housing clamps onto the nose of the worm housing and can thus be rotated for vertical or horizontal operation.


First test cut. 2'' diameter 6061, about 0.250'' deep, 3/8'' end mill. Over all it's quite accurate. I bought the tailstock from Grizzly. https://www.grizzly.com/products/gri...y-tables/g9296

[boydage]

Guys I really appreciate the response to this thread. I have thought a lot. I think I need to get my machine to a better standard before I start adding axis's. I have a few issues. Ones that I thought would disappear with the improvements I have been making. They are smaller, but still there. I am going to begin a new thread with the subject more focused. As now its getting above my level of expertise. I think I need some help to avoid spending money where its not needed, and that I dont have ha.