Help with making a 4th axis

[Archer60x]

I am looking to build a micro arc. Something that is precision (thus the harmonic drive). I have lots of experience with the motors and harmonics...it is just the attaching a chuck part that i do not have any experience with.

 

[mattthemuppet2]

you can make your own set tru three jaw chuck by drilling and tapping holes for four set screws radially through the bottom of the chuck. There's usually a recess there that is used to fit the chuck to the backplate. Then all you need is a register on the mounting face that fits the recess on the back with a little wriggle room to spare (axially).

If you know the dimensions and bolt pitch circle diameter of the harmonic drive nose, you may get lucky and find a chuck with similar matching dimensions so no adapter would be needed. It'll take some digging but it's worth a look.

 

[markba633csi]

Be certain that the harmonic drive you are planning to use can handle the dynamic loading if you are planning on
using the drive to hold workpieces for machining. As far as I know this type of drive is meant for transmitting a certain amount of rotational torque, but is the output shaft and gear train capable of withstanding the forces you may be placing on it? Both axially and radially?
Are there backlash issues with this type of drive? Can it be adjusted out? Need to be mindful of that too.
The concentricity is really a separate issue, just wanted to make sure you understood the difference

 

[extropic]

What is not clear to me are your intended/acceptable moment loads on the drive unit. Also, how much axial length you are willing to sacrifice to the "simulated spindle"?

The D1-3 or D1-4 (more popular but I didn't check the dimensions) would be quickest to swap chucks, but would probably be more than 2" thick and non-trivial to manufacture. It might be cheaper/easier to buy a D1 lathe spindle replacement part and modify it to fit your harmonic drive.

The shortest and simplest approach would be to make a single, relatively flat adaptor plate that will receive all of your needed flat back (front mount) chucks.

Set-Tru features will add some thickness but with obvious advantage.

 

[Archer60x]

I have no idea. I am making it up as i go.

I am just doing research now to see what my chuck and collect chuck options are so i can make decisions about the design. I am only working in CAD. I have not purchased anything yet.

Chad

 

[extropic]

I have no idea. I am making it up as i go.

I am just doing research now to see what my chuck and collect chuck options are so i can make decisions about the design. I am only working in CAD. I have not purchased anything yet.

Chad

My guess is that your harmonic drive unit is intended for rotational drive only and not capable of significant moment loads. That would require supporting your spindle on an independent bearing set (back to the "buy a lathe spindle"). If you have intentions of creating a functional and durable unit in the real world, I suggest you get a real understanding of the loads involved in the intended application.

 

[Archer60x]

Ya know i just came here to learn about lathe chucks, not get lectured and told how crappy on my non-existent 4th axis design is. So far i have learned more from google then this thread on different chuck types that i could use.

Yall keep guessing about my 4th axis design that i have not made. I will keep designing and building IRL.

 

[markba633csi]

Not lecturing, just pointing out design considerations early on so you don't have unpleasant (and costly) surprises later

 

[homebrewed]

Folks here like solving problems. Plus many have the "been there, done that" experience in this kind of application. No need to get impatient with suggestions that you think aren't on-point, who knows, maybe some may be useful down the road.

Good luck on your project. Please let us know how it works for you.