Internal Threading Away From The Chuck On A Steady Rest - Metric Threads Can't Use The Half-nuts
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- Опубликовано: 25 авг 2024
- Single point internal threading to a blind shoulder in some strut tubes for a 1989 Buick Reatta. Had to thread away from the chuck to control the stopping point to a blind shoulder. Also had to cut these threads on a steady rest due to the distance from the chuck. When cutting metric threads on an imperial lathe you can't disengage the half-nuts so stopping quickly at a blind shoulder is not an option. Cutting away from the chuck eliminates the challenge and you can cut at decent a speed.
Cutting a 51mm x 1.5mm internal thread on a lathe at over 600 rpm in Aluminum to a blind shoulder is manageable if you cut them away from the chuck. I also cut these same threads in steel strut tubes at 380 rpm using a PM 1440TL lathe (Precision Matthews PM 1440TL).
Struts for a 1989 Buick Reatta are no longer available so the customer came up with a modified design to thread the original strut tubes and insert the strut from a Buick Regal locked in with a Nut.
Left handed SHARS boring bar with lay down threading inserts.
How to calculate bore diameter for metric threads?
How to calculate depth of cut when threading?
Using the Machinist Pro Calculator from www.cncdirt.com to determine your threading passes when cutting single point threads.
Thanks for watching!
Bud Beets
BladsesIIB Knives
www.BladesIIB.com
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IMPRESSIVE VIDEO and machining, thank you so much, Paul down in Florida
@ypaulbrown - Thanks for the comment and the feedback. Glad you liked the video.
You can disengage the half nut when doing metric thread's. I can go into detail on how to do it but Abom has a video on it. That is how I do it and it is a great way to do metric thread's on a manual lathe. I like your approach at threading out of your bore, great work.
Marc Ward - Thanks for the comment and the insight. I would never have thought to try this. I did a little reading and watched the Abom video where he threads some Titanium rods. He does disengage the half nuts to stop quickly in his thread notch, however, he goes backwards and uses the thread dial to re-engage in the same spot on the lead screw and still runs in reverse to reset for the next cut. So The way I am seeing it, you have to clamp on the exact same spot on the lead screw and still run the machine both ways vs. how you would thread imperial where you can wind back and forth by hand? Let me know if I missed something or watched the wrong one. So, based on that, I will likely try this for external metric threading since I don't have an upside down tool to thread away from the chuck. For this project, stopping in the blind hole would have added another complication so I think leaving them engaged and threading away was my safest method. Then the coasting to a stop is a non issue. Also, from the reading I did, after you disengage the half nuts, you do need to need to make sure you don't move the carriage or let the thread dial go around past your mark before shutting it off. Just to make sure when you reverse you get the same spot. Not sure if that is true or not, just what I read so far. Will definitely have to play with this. I like having more options to use when needed. Thanks again for the great comment!
Cool project.
EZ Shop - Thanks! Good to hear from you. Hope all is well.
@@BladesIIB All is well thanks. Good luck at Blade Show. Ciao, Marco.
@@EZ_shop Glad to hear it. Thanks!
It's fun to watch "manual" machining, haven't done that myself in a while 😋. Some things I would like to "say":
- Squaring tools is easy to do with a parallell, on end at the chuck and one end at the holder. If the face of the chuck and the face of the holder are in line the center of the tool and the center of the spindel are so to...
- "Tolerance of dimension pretty close", remember the 25,4X difference between imperial and metric. Yes, 0,001"=0,0254mm so +/-0,05mm is +/-0,002". That is quite tight tolerances...
- Someone was either drunk or just used what was at hand to use M51*1,5, the "normal" among us "metric people" in my opinion is even numbers as M24*2, M36*3 and so on... Anohher way to get the bore "rightish" is subtracting the pitch from the diameter: M12*1.75→12-1.75→drill ∅10.2mm. Is there a similar "rule" for imperial threads? Yes, there are tables to look from, but us there a easy "rule of thumb"? Still wanting to learn new stuff 👍🏼😋!
- Maybe an O-ring to seal up the tube and keep debrie out of there?
Johannes Laxen - Always appreciate your comments and questions. Good tip on squaring the tool holder with a parallel, will have to try that one. Also good tip on the 25.4, I use it for converting but never thought to break it down to .001 is .0254mm or .002 is about .05mm. Will help me mentally think about this in the future for sure. As for the pitch, the tube wall is thin on this so I am sure that is what led to the 51x1.5mm thread. Doing 51x2 or 51.3 would have made the thread too deep for the this tube I suspect? As for the hole size, yes being able to subtract the pitch in metric does make it easy to find your bore size or drill size. The same does technically work for imperial threads as far as I know but the numbers are so random that it is easier to look at a chart. But for example a 3/8x16 thread has a pitch of 1/16 or .0625 and .375-.0625 = .312 or 5/16" which is the tap drill size for this thread. I have a lot of science background and know the metric system well, I just don't do much machining in mm and don't have many tools that measure in mm. Also, the customer said there is a rubber boot that goes over the top so that will do nicely to keep all the crud out.
@@BladesIIB My oh my, that was a really nice answer to me almost on the other side of the earth 😋. I learn alot watching your videos, thank you 🤗!
good to see you again
Tom Giorgini - Thanks, appreciate the comment.
Great job. Appreciate your sharing the setup and info. You do some great videos and some interesting projects.
Bruce Williams - Thanks for the comment. Glad the videos are helpful. They are fun projects and I hope the detail helps. If I ever skip a detail don’t hesitate to ask, always happy to share.
Your machining videos are always awesome i learn something every time wish i would of bought a PM Twainian made lathe that was a mistake i got a 14/40BV and the dang tailstock cracked thank god it is under warranty looks like to me the casting wasn't centered it is a hollow casting and was very thin on the side that cracked 95% of my work is gunsmithing i do taper cut barrels so the tailstock does get adjusted a lot
Owel just hope it gets fixed sooner than later. keep the good work Sir awesome channel
Greg - Thanks for the comment and the feedback. Glad the videos are helpful. That is truly a bummer about your tailstock. PM has great customer service, but I imagine that is still a special order part? Hopefully no issue getting it lined up height wise with your headstock. Sounds like you do some great work, I have a buddy who does gunsmithing, some interesting set ups for sure. All the best getting your lathe back in shape.
Just wondering what insert you used? Im guessing the internal thread going backwards is the same as external going forwards ?? You do make very good videos. Cheers
@richardmills5450 - Appreciate the feedback on the videos and apologies for not covering more detail on the boring bar and insert. This is actually a lefthand boring bar with a left hand threading insert to go away from the chuck in reverse. Still cutting a right hand thread but running in reverse you need a left hand insert to get it all going the right direction, relief on the correct side etc. Hope that makes sense, thanks for the question.
Beauty!
Blue Hornet - Thanks!
Looks Like You Need O Ring to Keep Water & Dust Out
Fort Next Time
@rek32839 - Thanks for the comment. In this case the strut is already fully sealed and ready to go on a vehicle as is. Fitting it in this tube is just to make it fit on a vehicle it was not designed for. So not additional seals needed. There is a rubber dust boot that goes over it.
So basically you have one chance getting this right lol. no pressure at all.
tdg911 - Yep, nothing like a little pucker factor to help you pay attention. I said "in reverse" out loud every time I ran a threading pass just to make sure I would start up the right way. Fun project, thanks for the comment.
@@BladesIIB No pucker factor? Not learning in my book. lol. I just finished a project that took me a while reverse engineering making sure my bolt holes were good for alignment so I 3D printed the pieces. Got one chance to make several plates for a jeep bumper armor plates so was puckering close to the end. No scraps and successful in the end :). Always great content you put out
@@tdg911 Nice! That sounds like a fun project. Glad it turned out well. Appreciate you always tuning in. 😁