MACHINE SHOP TIPS #17 Threading to Shoulder tubalcain

[@danbreyfogle8486]

WOW, 12 year old video and I enjoyed it as much as your current ones.

[@mrpete222]

Thanks

[@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.

[@russtuff]

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

[@geoffmorgan7424]

Thanks for refreshing my memory about how to do this. It had been many more than a few years since I needed to do this very operation. A couple of footnotes. You do NOT use the top slide compound to increase the cut, this will move the tool closer to the spindle of the lathe and will put your starting place into the shoulder of the work. The way shown means that both sides of the tool are cutting, therefore small increments of feed are necessary and the tool profile must be spot on. The other thing I found to be essential was to fit the carriage stop to the bed set at the starting point. This assured that I got the tool in exactly the correct linear position on return of the carriage. (I tried it the first time thinking I could spot the right place, not a good idea and I ruined the first go.) Be sure and check all your feed settings because when the lathe is run in reverse the carriage feed is also reversed; therefore on most lathes the feed direction will reverse also, so just make a "dummy run" before proceeding. Thanks again!

[@mrpete222]

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

[@minnesotahoby]

I was rethreading oilfield drill collars up in Alaska. These are tapered threads that run right up to a shoulder. I caught the taper and put my hand on the travering handwheel and bent over to see the cut. My hand acted as a brake of some sort and wedged the half nut closed. I couldn't release the half nut and crashed into the shoulder. I learned a lesson. "Never rest your hand on the traversing handwheel when the half nut is engaged!"

[@blmeflmm66]

Haha! I just got my first lathe and glad to see that "my idea" worked so well. Had a bolt that was badly dinged on the end and used the reverse and upside down setup to pick up the thread and clean it up. Found out later how to pick up the existing thread and run it normally. Love this method for those crash prone setups, though. Works like a charm. Keep up the great videos.

[@fall22123]

That's a really good idea. I've always turned it off and let it "coast" the last couple of threads, then turn the chuck by hand.

[@heliarche]

I'd love to have that gearbox on my lathe. On mine I have a box of gears and a chart inside the gear cover. If you want to cut threads it's a few hours, at least for me, to get the gears switched around to do it. I can't reverse my spindle either so I'd just have to be very careful.

[@jaketank3217]

Thanks for #17 Mrpete. I used this reverse method last night on a 18 inch long threaded rod so that I could take a nap between runs without fear of a crash. I just set the stop near the tail stock and let it run south until the feed kicked out!

[@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.

[@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.

[@mazzmari]

You're the man tubalcain. Great tip! Happy New Year.

[@joeb570]

Great information! I'm working on a part with a high shoulder and I have half a second to disengage the lead screw. It's an old engine lathe and the lever is a bit loose, and if you don't hold the lever up it will fall down and re-engage. This will help tremendously, I don't understand why it's not so popular of a method.

[@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.

[@whitecaps775]

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

[@zippy308]

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

[@havebenthere]

I've noticed on my older lathe that when threading, chuck mount, that the threads are somewhat looser the closer to chuck. I'm wondering about flex or wear somewhere.??????? Thanks for videos, I go back and watch some at times to brush up!

[@alfonse4595]

Great trick! I learned how to cut threads the proper way, by engaging the feed when the the thread dial is on a correct line. I can appreciate the running back in reverse trick though. It works just fine if your machine has reverse. You do not run in reverse back through the threads, that would be silly. And backlash would be a problem. You are already feeding the cutter in using the compound rather than the cross slide. So you set the cross slide dial to zero at the beginning. Then feed in at 29-30 degrees using the compound. At the end of the cut you stop, and back out using the cross slide. Then run back in reverse with the cutter away from the work. Then you bring the cross slide back to zero and then you are ready to feed in with the compound and take another cut.

[@mrpete222]

Yes

[@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

[@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.

[@nexus01gr]

Ahh... Great Ideas ... They always seem so obvious! Thank you, Mr Pete!

[@bigfootGeorgia]

That is a fabulous tip. thanks for sharing!

[@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.

[@eartaker]

Awesome, I am about to do some shoulder threading and I was wondering a way to keep from crashing since the piece I'm making will be small.. I will give this method a go. Thanks for all of the useful vids =] What about internal threading to a shoulder... I would guess running a left hand threading tool with the lead screw reversed would work but I only have a right hand threading tool. Any ideas?

[@beatnic50]

Great idea. Your brother is very creative.

[@gwheyduke]

Great idea ! Smacking my forehead, why didn't I think of this? I'm wondering if there are special dies for threading right up to a shoulder with small threads like 1/4 - 32 ? ( Model engine spark plugs.)

[@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.

[@poozor]

For those who say to simply reverse it, that's because you not a good machinist. If you are too lazy to do threading the right way (the way Southbend even says to), I know you will never hold really tight tolerances when it's critical. Laziness or arrogance.. Thank you MrPete and ignore the backyard machinists who haven't a clue

[@alehax27]

that's been something I've thought about but never actually done it. thanks for the video.

[@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

[@campbellmorrison8540]

Yes I like this way of threading too, far less risk and you can run the spindle faster which often gives a better finish. As far as I am aware the only cons to this is its harder to see the cutting tip and the job puts upward pressure on the cross side and tool holder but both of these seem minimal to me for small threads. Love your video's

[@jimbob1510]

i been watching you for awhile now picking up tips.. advanced student at the local college.. i just had a thought this method could be used for high speed threading in order to maintain correct cutting speed and get a better finish correct? and can you do this method on the 29 degree? with it be set up 29 traditional? or 29 lefty since your feeding the opposite direction?

[@ChimeraPrecision]

For a lathe with threaded spindle, could you run the spindle in the normal direction with the tool mounted normally, and put the leadscrew in the reverse direction so the tool moves left to right?

[@spaight711]

When you use this method, does one need to turn the compound to the left, like when doing internal threading? It just seemed to me that it would make sense, since the cut is being made away from the tailstock...

[@norbs]

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

[@hurst011]

Your problem could also be that your tool is not sharp enough and is causing deflection in the wok piece. As you get closer to the chuck, the rigidity of the wok piece forces the tool to cut deeper. Clear as mud?

[@Duckyistrippin]

if you have a thread on chuck or the machine doesnt reverse you can put the bit behind the work and upside down, so you dont have to reverse spindle direction or worrying about the chuck falling off ;)

[@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?

[@jxgreer]

Do you need to change the angle on the compound?

[@tomherd4179]

I can see where this would be a great way to thread. But on some lathes with screw on chucks (SB 10K) how dangerous is it to do this in reverse. I personally would consider doing it for light threading, but for heavy work it would be taking a risk. Too bad there was not some way to "lock-in" a screw on chuck. Guess a collet would be full proof.

[@hurst011]

I suspect that you have a bit of tool or work piece deflection and should try taking smaller cuts. You could also take the cuts as you normally do and occasionally stop feeding in the compound to let the piece clean up while making a couple of passes. The last several passes without feeding the compound will make diminishing cuts on the work piece until it almost looks like it is peeling fuzz from the thread. It is a "learned feel" that comes with experience.

[@bcbcbc55]

great ideas, thanks for sharing them

[@MrUbiquitousTech]

That IS a good trick! Thanks for sharing!

[@ronaldcrowder404]

I'm left handed so I wondered if that could be done in reverse

[@henryeversole5988]

Great idea for threading rifle barrels

[@VRsarojcomedy]

Thank you

[@mrpete222]

You are welcome

[@jxgreer]

What about the angle on the compound?

[@DimaProk]

Would same method work for internal threading? I think it should... I just ended up making a left hand thread because I had my tool pointing AWAY from me :) lol.

[@MichaelTravnikar]

Very smart idea...

[@mrpete222]

Thanks

[@normanclements2615]

Hi Tubalcain, most of the content of your machining tips are very good, but I don't agree with your comments about not stopping and reversing the lathe when threading short lengths of thread. At low speeds lathes stop pretty quickly and before you return to the start you have to withdraw the tool regardless of the method. Also for inexperience machininst or cutting metric threads with an imperial leadscrew it avoids engaging the half nuts at the wrong time on the thread index.

[@RollingEasy]

I wonder if you could jig the same method here into Metric Threading? I'm probably going vague with time but I seem to remember there is a way of cutting Metric where the half nuts can be disengaged just as they are with Imperial threads?

[@lordchickenhawk]

I find it best not to disengage if the lead-screw is Imperial when cutting metric threads. It is possible to do so by adjusting the position of the tool with the compound slide for every cut but it's a lot of mucking about and not all that accurate.

[@RollingEasy]

I've never tried this reverse method but today I'll give it a go. Even with having a power cut off, its nerve racking towards the chuck and I can see how reverse would take that part completely out of the job.

[@lordchickenhawk]

Yeah, that's still something I get edgy about, even after 35 years. The big advantages of the upside-down method are that you can safely and easily run at much higher revs so you get a better finish on the thread flanks... and it's a fast method too. It's a bit more difficult to set up the tool but if you're making lots of the same thread it's still good. On some lathes you may have to make a special purpose built tool holder. However there are two major disadvantages you need to watch out for. Firstly, as mentioned in the vid, don't do this with a screw-on type chuck. It can spin the chuck off... most embarassing. Secondly, some old flatbed lathes do not have a saddle that "wraps around" the bed. The lifting forces generated at the tool tip tend to lift the saddle off the bed, ruining the work piece. The same can happen if you have much slop/wear in the cross-slide or compound-slide dove-tails. Adjust them up before you start. Also, don't bother with this method unless you have a lathe with proper dove-tail guide-ways. Old flat beds sometimes had square cross-slide guides and these can lift up. Use your Mecha-nous and you'll be fine. I thought I was soooo clever when I discovered/invented this method for myself as a young fella that I was a bit disappointed when I found out I was not the first bloke to think of it by a long way! Happy turning! Chook

[@RollingEasy]

lordchickenhawk I was tapping 1.75mm pitch threads into lugs held on a bracket on the toolpost and using the chuck to get them best centred and started. (Manually turning the chuck in neutral). There was tightness when I engaged the half nuts. I assumed that gear ratios allowed for a tiny % error against a machined tap? Meaning tapping and single point threading are almost the very same but not quite. What would you think?

[@lordchickenhawk]

In theory they should be the same. I've never really tried tapping in the lathe by putting the tap in the chuck. How did you get the tapping hole centred and in alignment with the spindle axis? By drilling it with a drill in the chuck? If not, even a small mis-alignment between the spindle axis and the tapping hole axis could result in binding, especially once the pitch is being forced by the half-nuts. Usually when tapping with a lathe, I like to put the tap in a jacobs chuck mounted in the tailstock and put the job in the main chuck. I then leave the tailstock free to slide along the bed and let it pull itself in and out as the tap requires. That's my thoughts on the matter, but without actually seeing what exactly you are doing I can't really say what's best since I've not actually tried this, like I said. Perhaps it will work if you leave the half nuts out while applying GENTLE feed pressure on the saddle hand wheel. You should be able to feel resistance changes as feed back while you turn the chuck with your other hand. Don't forget the love-gel and let me know how it went.

[@robertduncan2742]

Looks like delrin can be machined slow. I've watched other films saying the white doesnt machine as good as the black. Thank you

[@Tom-ic7hw]

is the compound angle set to 29 °

[@mrpete222]

Yes

[@jacobvincent5861]

Awsome

[@pmfsv]

mrpete222 you got me hooked...:D

[@lyndone.2682]

I've got an SB-9a w/ a thread on chuck. I know that if you try this method (as shown), your chuck will spin off. Has anyone tried anything to lock the spindle on the SB-9a? I've been thinking about drilling and tapping a set-screw hole in the rear flange of the chuck and barely touching the spindle. Thoughts?

[@mrpete222]

I would very much like to find a good way to lock the chuck on the threaded spindle. Maybe that would work I do not know.

[@Triquetrahikist]

I suppose for hobby machining leaving the half nut engaged is fine, but if the thread length were something like 10 inches or even 5, that process becomes painfully slow. If my boss saw me doing that I would be chewed out, unless it was a metric thread. Where I work it's a race to the finish for everything.

[@xKmotx]

Dang brilliant! :)

[@Fixinthatupvideos]

T=up

[@havebenthere]

You would be cutting a left hand thread! A person really has to almost make a visual aid to keep threading various ways understandable. Machining is a thinkers world.

[@mrmatt2525able]

knice

[@Duckyistrippin]

he is talking about reversing the machine to back your bit up. not working upside down and away from the chuck. and he is right. kicking the machine into reverse instead of using the half nut correctly is hack machinist shit. just because you are a hack and were taught by hacks doesnt mean its the right way. Mr pete just explained to you clearly and concisely why you dont do it. with the backlash involve you are dragging the cutter in reverse rotation which dulls it. believe it or not, its fact.

[@mikehorn6457]

are you sure you understand yourself what you're talking about? the only way to dull your cutter is by not lifting it when returning to start for the next pass. since you obviously don't know that you're probably a hack machinist yourself taught by hacks. keep ignoring however the reversing method is as proven as the one in mrpete's video. just because it's not your personal preferred one doesn't mean it's wrong, that's the only real fact !!!

[@mikehorn6457]

In this particular situation this method to run away from the chuck ist certainly the better method however anyway all designers will work with an undercut anyway. Finally - to simply say that the stop and reverse method is used by poor machinists only is b....sh...! working now in the mechanical industry for +35 years and learned it that way and never had problems. anyway all the lathes used in the different vids are not even 2nd but 3rd class quality machines.