MACHINE SHOP TIPS #17 Threading to Shoulder tubalcain

[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.

[bigfootGeorgia]

That is a fabulous tip. thanks for sharing!

[norbsli]

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

[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.

[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

[whitecaps775]

Hello, Many thanks for vids. How many thousands of cut for threading steel, same as vid? No experience here...maybe soon.

[GK1918]

Just wondering, what if one were to run up the tail stock dead center to the work,

that should prevent the chuck spinning off? I should think. SP

[cannonball666]

@mrpete222

About keeping the half nut engaged constantly: I understand what you mean by backlash becoming a thread-damaging factor if you reverse the lathe. However, that is only the case if you don't back the cutter off completely before reversing.

[mazzmari]

You're the man tubalcain. Great tip!

Happy New Year.

[necedm]

I love your vids!

Question:

What set up would you recommend for internal threading? (not using a tap)

Do you use radial feeding instead of flank feeding?

[ytmachx]

This is the method I use for threading blind holes.

[russtuff]

i can't get over how great your video looks with the new camera!

great series! keep it coming!

[coriander2]

Good idea! Another tip saved to the memory bank. Thanks for posting

[outsidescrewball]

6am here and just started my day learning something new, you can't find that technique in a book....my lathe (crash) and I .thank you

[Petawatt]

Could you please do a video on using a micrometer at some point? I know how to add up the dollars, quarters, and pennies, and how to read the ten-thousandths digit, but I'll bet I'm missing something and I'm sure it would be helpful to everyone else too.

[Petawatt]

Thanks again. I never had a shop teacher, and picked up what I know about machining from books as HSM (& projects in metal) only. I had the distinct impression that this procedure was preformed with the tool mounted upsidedown on the far side of the lathe, but I see now that would not get you anything.

I suppose you could also mount it on the far side, right-side-up to do this operation, but you would still have to run the thing in reverse, which you pointed out is risky on some lathes.

[xKmotx]

Dang brilliant! :)

[mrmatt2525able]

knice

[JohnLoganMcKee03]

klever!!!!

[zippy308]

Pretty nifty trick. Is your video on acme threads coming up soon?

[SciStarborne]

Was wondering about running it backwards like this! Question answered before I asked! Didn't think of the backlash issue.

I'm sure I've seen pictures of someone who affixed a removable manual crank to their spindle for some reason, it might have been for threading. Might be another option for exceedingly tight to shoulder threads? Albeit likely a lot slower.

[Superpickupline]

@SciStarborne you most likely saw a collette chuck configuration the hand wheel is connected to the drawbar which tightens the collette much like that of a r8 milling machine set-up.

[alehax27]

that's been something I've thought about but never actually done it.

thanks for the video.