MACHINE SHOP TIPS #17 Threading to Shoulder tubalcain

Tubalcain shows how to thread up to the chuck or shoulder the safe way. UPSIDE DOWN. I'm threading white DELRIN plastic to speed things up.

Category:

Science & Technology

Tags:

• bridgeport
• mill
• south
• bend
• lathe
• atlas
• clausing
• delta
• logan
• hardinge
• rockwell
• starrett
• steam
• engine
• stirling
• john
• deere
• ridgid
• toledo
• ream
• tapered
• threads

[oneeyedmac]

When a rifle receiver is accurized one of the processes is to re-cut the receiver threads so they are perfectly in line with the axis of the bore. So we have to line up the tool and thread into a blind hole. It's not hard to wreck the tool and the expensive receiver if it's not done right. Is there a way to mount the tool upside down and start inside the receiver so basically we're threading from the inside of the hole out? That would make life less stressful.

[mrpete222]

@oneeyedmac Yes. I have heard of gunsmiths using this method. You will need an undercut in that hole to start the thread.

[akotoun]

Ok, rookie here, what is the advantage of mounting tool upside down? is it because we are feeding L to right and now the cutting surface of the tool must be on the right side of the tool? why not just use an opposite side cutting tool? and my last rookie question is how do you adjust the height of the tool? I have a south bend 9a. Any and all help would be greatly appreciated.

[mrpete222]

@akotoun The spindle is being run in reverse, so the tool must be upside down. Otherwise it would be rubbing-not cutting. Set your tool on center ( with the tailstock center) . Height adjustment with the rocker wedge under the tool holder.

[bigfootGeorgia]

That is a fabulous tip.  thanks for sharing!

[norbsli]

Thats a great ideia, how did I didn't thought that before!!

[beatnic50]

Great idea. Your brother is very creative.

[pmfsv]

mrpete222 you got me hooked...:D

[rettibotta]

I have watched all your metalworking videos, and I have learned a lot. Thanks.

I have a comment on reversing while leaving the halfnuts engaged: I think there must be misunderstanding. You must, as you say, retract the crossfeed before you reverse. I have never heard anyone saying otherwise. The reversing technique is useful if you don't have a threading dial (my mini lathe did not come with one) or when cutting an imperial approximation on a metric lathe (or vise versa).

[bcbcbc55]

great ideas, thanks for sharing them