Threading square stock / workholding at the mill

[r-mm]

Hello all

I am looking to recreate this small aluminum specialty bolt. It is made from bar stock and threaded M5-1.0. I am looking for advice on: how to hold this work at the mill and what dimensions to cut the square shank to in order to thread it.

I'd planned on starting with 4mm bar stock.

Thanks

 

[ChazzC]

I’m confused: you’re starting with 4mm square stock? It looks like you need to use 10mm or 12mm, 1/2” stock to get the width you need.

How I would make it:

• Put stock in a 4-jaw in the lathe, turn and thread the end
• Cut stock to rough length
• Holding threaded end in a collet in a square collet block in the mill vise, mill thickness (remove half the “excess” stock, rotate block and remove the rest) & then mill to finished length.

Charlie

 

[r-mm]

I'd planned to start with 4mm bar (but not square) stock. https://www.mcmaster.com/9146T31/

Thanks for the advice I'd not thought about using the lathe, I'd planned to thread the rectangular stock with a die. Perhaps threading it as the last operation (by hand, with a die) would give best purchase in the collet block.

 

[ChazzC]

I'd planned to start with 4mm bar (but not square) stock. https://www.mcmaster.com/9146T31/

Thanks for the advice I'd not thought about using the lathe, I'd planned to thread the rectangular stock with a die. Perhaps threading it as the last operation (by hand, with a die) would give best purchase in the collet block.

Making it from rectangular bar will be more difficult. I that case I would just to a workable length (so you can clamp the flat end in the 4-Jaw), then rough saw the profile of the threaded end. You could then turn the threaded end (to what appears to be M6?) in the lathe (but carefully since 4mm bar is not very rigid) use a die to cut the threads and just finish the rest of the part on the bandsaw and filing/sanding.

 

[r-mm]

Were you suggesting starting from rod? I suppose there's no reason I couldn't turn the threaded are down to ~5mm, set in collet block then mill the flats into the ~12mm rod then finish with a die.

 

[ChazzC]

Were you suggesting starting from rod? I suppose there's no reason I couldn't turn the threaded are down to ~5mm, set in collet block then mill the flats into the ~12mm rod then finish with a die.

At my computer now (was on the phone previously so hadn't downloaded the drawing). Does it matter if the treaded part stays round, or does it need to be 3.6mm thick to fit through a hole?

I would start from 12mm square bar the size of the widest point, then proceed as I outlined. But could start from round bar as well. To minimize the amount of material to mill away you can rough cut on the bandsaw. after turning the end.

The manufacturer probably started with 3.6mm sheet, punched the profile of the part out then threaded the end.

 

[ChazzC]

You could also start with the 4mm x 12mm bar:

• Saw to rough length
• Hold flat on parallels in the mill vise machine to 3.6mm thick & drill the hole, then clean up the ends to finished length
• Rough out the 5mm portion on the bandsaw
• Place on edge in the mill vise so the full length is clamped by the jaws and mill one half of the 5mm portion
• Flip and mill the other half of the 5mm portion, again clamping the full length
• Hold on edge in the bench vise and thread the 5mm x 4mm rectangle
• Round the big end by filing or on the belt sander

Alternatively, just use the bandsaw, files & sander to make the profile and then thread the end.

 

[Makintrax73]

I'd probably start with 1/2" round stock just so I didn't have to change chucks on the lathe, and there's always some laying around. Turn it to size (ie the size of the width of each section), thread it, part it off leaving some 1/2" on the end for workholding. Put it in a collet block and mill each side down. Cut off the tag end with a hacksaw and clean it up with a file if you're feeling froggy.

Lots of ways to skin this cat. Always interesting to see how different people would approach it.

 

[r-mm]

Yep this is what's in the lathe right now. Just popped up to the computer to find the right OD to turn the M5-.8mm threads (typo on my drawing calling them M5-1.0)

 

[r-mm]

Yep this oughta work