First project - Delrin ring roller die set

[sru_tx]

Learning how to use a lathe, specifically my PM1128. I bought the lathe mostly to make some custom tooling and here's where I'm starting. Curious how others would go about making ring roller die for bending square tubing along the diamond shape (steel version pictured below) Material: delrin. 4" diameter. 2.5" width. 90 degree between faces.


My plan:
Assuming the distance across the V is 2", then the depth is 1" and the angled face is 1.414" = 1" /cos(45deg).
With 2.5" width of die and 2" across V, then flat is 0.25" on either side.
1.Set the compound to 45 degree.
2. touch left cutting tool to end of faced stock. pull back tool with cross slide, move saddle in 0.25" and lock saddle.
3. touch cutting tool to outside of diameter and zero compound and cross slide dials.
4. Initial cuts made by advancing compound feed.
5. As depth of cut gets too deep, back out cross slide, advance compound, then cut by advancing cross slide until it reaches zero.
6. repeat step 5 until compound indicates 1.414" (center of part).

Swap tool for right cutting tool and move compound 90degree for the other 45. Repeats steps 4 thru 6.

Does this sound reasonable or overly complicated. Thoughts?

 

[Bob Korves]

Sounds well thought out. I am not sure how this is mounted or how it is able to rotate, but I would try to make two cones and then bolt them tightly together if that is a possibility. If what appear to be the bearing or mounting surfaces are all you have for diameter and width there, I would recess the fasteners in the side faces. The shaft could be made from larger all thread with the ends turned down to serve as bearings. Or is that a through shaft with bearings in the outside faces of the cones?

 

[Bob Korves]

If it is to be made of Delrin, what are you planning to bend?

 

[sru_tx]

Through shaft. bearing in a counterbore. collars on either side keep the die centered. Ring roller shown below.

Using Delrin to bend aluminum with less marring and gouging than the steel set.