Machining steel round outside diameter on vertical mill

[JimFromAZ]

Hi All,
I'm making giant steel washers for my bench grinder (one step in trying to eliminate vibration, and, yes, I'll dress the grinding wheels). These disks are 2.5" in diameter and I'm milling them to 0.250" thick on a manual PM-728VT. The next step is to mill a 0.625" center hole which should fit perfectly on the bench grinder axle.

Finally, I want to mill the outside diameter concentric with the center hole. The final diameter isn't critical but I imagine I probably need to remove 5 or 10 thou. I don't have a lathe, just the vertical mill. How do I mill the circumference? On a rotary table? If so, and assuming I now have that 0.625" center hole, is there a recommended way to mount this disk to the rotary table? Any suggestions other than a rotary table?

Thanks Everyone! Jim

 

[RandyM]

Before I got my lathe I used a boring head to do things like this. It is unconventional, but it works.

 

[jwmelvin]

You could make an arbor to hold the bored disc in your spindle and use a single-point tool in the vise to true the OD.

Edit: probably more properly called a mandrel, as it holds the work rather than the cutter.

 

[Weldingrod1]

You could clamp it down with 2+ clamps out near the edge. Make sure its centered on a T slot. Pack it up off the table with something so you can go all the way through and make sure you won't hit them with the boring head.
Indicate the OD for decent centering.
Drill and bore the center first.
Install a clamp in the center and then remove the edge clamps.
Using a boring head, cut the OD.

Sent from my SM-G715A using Tapatalk

 

[talvare]

I think jwmelvin has the best approach to this task. This will greatly reduce set-up time and effort and should produce excellent results. And, when this job is complete, you will have a new tool to add to your collection.
Ted

 

[JimFromAZ]

Before I got my lathe I used a boring head to do things like this. It is unconventional, but it works.

Thanks, Randy! I have a boring head on my short list.

 

[JimFromAZ]

You could make an arbor to hold the bored disc in your spindle and use a single-point tool in the vise to true the OD.

Edit: probably more properly called a mandrel, as it holds the work rather than the cutter.

Interesting idea. I had thought about mounting the work piece in the quill somehow, but then I said, No, that's crazy! Well, I guess it isn't. I'll definitely give this some more thought. Thanks!

 

[JimFromAZ]

You could clamp it down with 2+ clamps out near the edge. Make sure its centered on a T slot. Pack it up off the table with something so you can go all the way through and make sure you won't hit them with the boring head.
Indicate the OD for decent centering.
Drill and bore the center first.
Install a clamp in the center and then remove the edge clamps.
Using a boring head, cut the OD.

Sent from my SM-G715A using Tapatalk

Thank you, Sir! Yes, a boring head is on my list. I'll need to learn how to use a boring head to cut the OD. This is my very first milling project, so experience is lacking! Take care...Jim.

 

[chips&more]

And take off that tie before you operate any machinery!

 

[RaisedByWolves]

And take off that tie before you operate any machinery!

LOL!!!


Jim, if you do this properly you could work the mandrel into a nice slitting saw arbor so its not a one time use part.

Im always looking to find a secondary use for something that needs to be made as a one off tool.