Nice Joe, i'm a french Canadian and i spent 40 years in machine shop and it went by like a flash i am now retired. I used this setup all the time but to center my piece i just put a little pressure on it and centered it using a piece of wood in the tool holder and manually turning the chuck to rub on the piece of wood and it would center very precisely when i needed precision suppose i had only like .010-.050 to take off on the already round part. Thanks a million Joe you give me nostalgia....have a nice day!
I got a piece that was sheared to more of a rectangle than a square once. Right at the end of this operation, the material broke through and broke off. It came off in a string of 4 curved triangles with razor sharp radiused inner surfaces and needle sharp points connected by a remnant burr you could shave with. It was about 2 feet long and 1/8" thick. It was no doubt the most potentially damaging swarf I've ever seen ejected from a machine ever.
@@joepie221 my first experience with this was a piece of plexiglass that was 12 in in diameter and about a quarter of an inch thick. In addition to being brittle it wasn't uniform in thickness and I did not know this until I started to cut it about 400 RPM. The part ended up melting in front of the tool and the tool quit cutting. The outside diameter the part proceeded to explode in all directions and a moment later the part completely cracked and came out of the machine in three pieces. Do not turn plexiglass this way.
In having my students do this over the years I have also discovered if you use a tool bit with a 45 degree lead angle rather than a rather abrupt 90 degree lead, that you reduced cutting pressure on the work piece dramatically. And as Joe points out, anything you can do to help out in this type of operation is to your benefit. This is the same thing that takes place in face milling when you use a face mill (insert style) with a 45 degree lead angle vs. A face mill with a 90 degree or square shoulder. If you are trying this for the first time I would recommend you bandsaw the rough circle out.
Be careful putting angles on the nose of your tool. An 1/8 inch wide 45 degree nose tool has more surface contact than a blunt 90. If I understand you correctly, the part would have a large sharp burr on it once the corners fall away.
this guy has such great tips and shows so much. I think its really nice that a pro machinist like him is willing to share his way of doing things, and also to "teach" other people thing trough the internet. It probably cotst him some valueable time, but i havent come across a more skilled machinist on youtube yet that is sharing so much information.
Hey Joe, I've done this over the years (40). I've opted for a thinner profile bit, made of carbide, with larger face relief, to form a sharper point. Works very well... I've had my moments. Thanks for spreading the knowledge to all the newbies....they need it!
Wow sir, I completed my apprenticeship in '90, done everything from medical valves to battleship prop shafts in a variety of shops and had never seen nor heard of this. Now a simple hobbyist with a fairly complete home shop, I will certainly use pressure turning when the opportunity arises. Seems like smaller diameter pieces wouldn't even induce much terror and yes what a time saver. Thanks!!
I never heard of pressure turning or trepanning. But, I have been doing it for many years. I thought I may be the only one, first time I have seen anybody else do this. I devised method 2, trepanning, but my tool also has a profile on it too. It always lets you know it is about to break off with the noise you hear in this video. I devised the set up with a backing plate just a little smaller than the part. Never had any problems. I figured someone else must be doing it, logic says, and finally, here it is. I was doing 20 pcs about 3 times a year, but less frequent now. Definitely a great setup to loose body parts, seriously injure other parts, possibly even get to see if there is life after death.
Joe, you are a valuable resource in my toolbox! I would not call myself a machinist but I have had a few lathes. I have seen more recent tutorials where you demonstrate this technique. I came back to this video. I just built an ammo box stove and made 2 1/2" stove pipe and needed a damper plate. Not satisfied with making one out of ductwork sheet metal, I used pressure turning and trepanning to cut the damper from the centre of an octagon box cover. I owe you man!
I don't know how I got to see this video but Thank you So much for being so thorough, I am a CMM technician and have no Idea what's going on in the machining process. So very much happens amazing. Thank you very very much for posting this.
Early in my career I knew some manual metal spinners some of them were missing digits from this exact type of work. Indeed wise to use extreme caution when this work is necessary.
I had never seen this technique before. I appreciate the new addition to my arsenal, and in particular the heads up on the dangers of trepanning this way. Excellent video for which I am very thankful. Yet another good one! Sorry about the sad loss of your dear friend.
You had me holding my breath on the second part!- Sorry to hear of your loss, I lost my wife of 25 + yrs to brain cancer (in 2011) and I don't know if I could have kept the same up beat attitude and smile every day like she did knowing that you are not going to be around to see your youngest daughter Graduate High School she was the strongest person I have ever know or met.
Thanks for sharing this useful operation with us. A second circle slightly larger than the diameter of the pressure disk would help to locate the larger disc on center.
If you back plate was large enough, a series of short dowel pins could be added as locators and drivers for the various blanks you use regularly. It would help, but ( downside) the burr / cutoffs would come towards the tool and not the chuck.
Wow. That second procedure made me nervous just thinking about those parts flying across the room. I built a attachment for my 4" grinder to attach to my lathe to take off the square corners before I turn a part. It takes a couple of minutes to get those sharp corners off, but I feel better afterwards when I machine the part.
Hi Joe - Very neat information - at some time I am going to make a larger throttle butterfly, after I enlarge the the throat of the inlet manifold of my car. The bit that has thus far stopped me was how to machine the butterfly - you have answered the question. Thank You
Those butterflies should have 2 center holes in them to hold them to the shaft. Put those in first and screw the blank to the face of a soft arbor. Basically work backwards.
glenn whitchurch Just a note Glenn. Most butterflys aren't round. I machine them for carburetors and injector stacks fairly frequently. Most of them are 8 or 9 degrees. Mount your workpiece to an arbor milled to the appropriate angle and tapped for the necessary screw centers. Use a backer piece to mount the butterfly to the arbor. Stack three or four discs to the arbor. The middle ones will be burr free. Check your diameter only at the screw/ shaft centerline. Turn the butterflies 4 to 6 thou smaller than housing bore. It's kind of a wobble plate nightmare when you are machining it but that's the only way to get good closure on the throttle housing. Check the edge of your existing butterfly when you get it out, if it's not square to the plate read the angle and go for it.
Since it technically seals in a radial trajectory about the shaft centerline and is driven by the bore diameter, you may be surprised at what you find if you inspect it closely. Different on each side I bet.
Great video, I can see how useful this would be for turning thin walled parts that a chuck might warp in order to grip it as well. It's actually quite amazing what you can do friction and it continually surprises me how diverse it's applications are becoming. To get a better idea of how strong friction can be, a quick an easy experiment one can do at home is to take two books of about 100 pages each and interleave each page as far into each other as you can all the way through both books. Once that's done, see if you can pull them appart by the spines. JSYK, the correct term for a throwing star is shuriken and hails from Japan ;) Anyhoo, I love all the sound advice, techniques, tips and tricks you empart, I value it all highly as a relatively new and eager home shop machinist. keep up the awesome work my man, I'm loving every minute of it :)
I love your attitude towards danger; You inform, but then keep on to show -and keep on to show that experience is what you need to do that safely! Great.
Hey Joe. Seeing your channel for the first time. Former (90%... ish) manual machinist and enjoy seeing a skilled tradesman at work. Almost miss the smell of cutting oil and dykem... almost. Legitimate question. Is there a reason you used a relatively wide trepanning (plunging) tool for the OD on the square stock? And for all of the frightened non-machinists... This is not a super safe cut, but it's a fast way to get a part out the door. Speed in turn around on jobs is the name of the game. If you ever really want your pucker factor upgraded, watch an old VTL machine with some stringy material cuts. Keep making those 6's and 9's for the rest of us, you definitely have a new subscriber.
The ideal tool for this operation would have the cutting profile on the outside of the tool. That would allow for a thinner grind. With the tip positioned to the inside, ( like this one ) the underside relief weakens the tool considerably if the top is too narrow. Plus the material was soft enough to allow for a wider tool.
I use an MDF face plate and use double sided sticky tape between it and metal. This allows me to cutvinto the wood. I also use more tape if adding extra discs for stacking. Slow speed..and gentle advance.
Saw a guy who used double sided sticky tape on the face of his chuck,he set the stop so the tool just touched the tape, when he cut through the off cut stayed there and took some prying to get it off, he also used the tail stock center to apply pressure.
Very Interesting. I have to do this kind of job several times a year with 1/4" thick material. I cut the blank square and hold it by the outside edges in a four jaw chuck.....so not pressure turning....when I cut through (or almost) I stop and tap the circle out later once removed. Joe's method here will make me think next time about trying it! Thanks Joe.
Why didn't you draw 2 lines across the corners corners, then draw a circle equal in size to you center block so you could take the guess work out of lining it up?
May be a dumb question, but why not mount the cutter upside down and run the machine in reverse? Still pretty dangerous cut, but at least then you would have material rotating away from you and if it did come lose, it would hit the back panel or the ways instead of flying at your face, right?
If the workpiece can have a center hole, start by drilling center partway through with standard 60 degree center drill. Then pressure turn between that (tailstock live center) & the chuck plate. The workpiece is positively held throughout the process. To center already cut-round work, clamp work lightly & HAND TURN spindle while letting toolholder rub against work and slowly feeding in. Setup works like wiggler finder; the work tends to center itself unless you overfeed the tool. When manually centering work, use small mallet to tap work on center. Movement is much more controlled and there is less tendency to offset tailstock.
The larger the pressure pad, the better. On a part this size, you can be assured a single center would let the part slip under load. If you are allowed a center hole, make a cap with a recess and bolt it securely
Nice, I have done this in the past a couple times with very thin material using a large driver and pressure puck. I's been a few years but I may give this a shot. I like trepanning , done a nice piece on video for my indexing angle plate build. I'm new to your channel, thanks for the video. I subscribed and belled you
Joe. Fantastic tutorial .. as always. Can I ask on behalf of us slow oldies that you leave your written comments on screen a little longer please. Steve.
What are the pros/cons of doing this way vs. the superglue approach that Clickspring often uses? Not sure I'd have the courage to do this on my baby 9x20 lathe. If I needed a big circle, I'd probably bandsaw and belt-sand the part to size and suffer with the total lack of precision.
Tad Harrison time constraints. That is an awesome way if you are doing a few, but, doing hundreds or thousands of parts, gluing, heating, and cleaning the chuck between parts will take way too long unless you have a few people to do other steps with lots of glue chucks.
Joe Pieczynski my suggestion would be to spray adhere your paper/super fine sandpaper material to the drive and tail stock surfaces so there is less messing around. Just a thought.
If your tailstock is not as strong as a vice this should not be attempted. If there are any variations in the thickness or flatness of the workpiece you may get uneven grip. I would suggest supergluing a flat rubber ring on each pressure plate. The rings should be about 1 inch different in diameter to suppress vibration and between 1/2" and 3/4" wide for about 4 to 5" diameter good for cutting up to 12" diameter. Use 1/16 to 1/8 thick rubber. This will conform to any variations in material surface and give maximum grip with no need for paper or Emery cloth. Larger diameter cuts will need larger pressure plates and rings. Always feed by hand because if the tip breaks or gets dull it will be more likely to throw the part out if its power fed. I've been a manual machinist for 20 years and finding the safest most productive way to do dangerous jobs is what I do. Still many are better than me. Remember safety precautions only mitigate risk they don't eliminate it. Work carefully at your own risk.
This kind of operation is far less hazardous if you have a variable speed drive. With a geared lathe, you have huge amounts of torque that you don't need and definitely don't want in situations like this. The slower you go with a geared lathe, the more torque and the greater the danger. With a variable speed drive on a geared lathe, you can select a high gear and then use the drive to drop the speed to what you need. The torque on Variable speed drives drops off as the speed decreases so you can set it up so that it will just stall if things jam up. This technique is very useful when parting off under power too.
Hi Joe, I just subscribed, this is the second video I have watched of yours, WOW! I bet OHSA has some thoughts on this procedure...... Your stressing SAFETY, is spot on... Looking forward to running through your catalog of vids, nice to meet you ....in a YT way!!
Paper towel is a good buffer, I use the butt of a tool bar gently against the plate with a little tail stock pressure to the plate to center it, works well and saves extra cutting.
Another great video Joe. I have used this technique on smaller plate and always avoided this for plates as large as you show here for the very reasons you so well point out. I do have a superglue plate someone else mentioned and is another good technique, in my case I made .250" deep slices with about .1875" spacing on a horizontal mill. When you're done lathe machining, drop the superglue backplate, part and all in a shallow pan of acetone and the part will fall off in short order from wicking up the channels. Something for my channel if I ever get the courage to do some videos. I'm not so good at video editing., lol.....
Joe Pieczynski , so what do you use to edit now? They look fine to me. I'd like to make another vented slot superglue plate and might be my first video.
Thanks for sharing this method - a great tutorial. Sorry hear about your friends fight with cancer. I have a close relative with the same type of tumour...
I watched on my 22" monitor and turned my head sideways, lol. I'd be farming these pieces out to a shop to water jet. a couple of days turn around is worth my face. Great video though, I love this stuff.
I find that a healthy pucker keeps you safer on the lathe in general, but this particular operation requires a sphincter clenched so tight it makes your hemorrhoids scream.
Nahhhhhaaa as an 80 year old old machinist (with all my fingers ) I would head to the band-saw. Sorry about your close friend, Prayers go out to you and his extended family, I lost a friend some time ago, your perfectly correct, seems if you have five friends like that in a life time, your lucky. Take care and keep preaching SAFTEY
I wonder if you could use a rubber(like old car tire inner tube ) instead of paper,to make it more secure and reduce chance of that thing flying out.I had a mini heart attack when i saw you trepanning that thing. There is one more thing you could do but it takes a little bit more time-you could use plywood to make some sort of face plate(or use one if you do have it )and then use screws to hold aluminum (like drill the holes in corners and attach it with screws to a plate ,then you can push tailstock center and trepann it safely without fear of thing flying out and killing you. ) Many ways to skin a cat! Thank you old timer for sharing your life long experience with us.
i used that on a lathe once when i needed to make a custom copper washer ,from a flat thin plate of copper.I used peace of plywood put it in a jaws and just used wood screws in 4 corners.
Joe could you make a video about what to look for when buying used machines.Like how to check for backlash on a lathe,how to check for wear in the lathe bed,what to check when you buying milling machine ,drill press etc.You can cover basic shop machines like drill press ,lathe ,milling machine,bandsaw,tool grinder.
Double stick tape holding the center section on a sacrifical platen. Corners restrained. Trepan tool on mill. Faster to set up and and about the same run time.
Not always available and takes a bit of investment but a CNC-mill and vacuum-table would definitely be a safer way. (Drawback, only possible to break/chamfer one side in one set up)
R K You could use a clamp on each corner, go past the bottom of the material with the end mill to minimize the burr, chamfer both top and bottom edges with a double angle chamfer mill and Voila!! One single operation and one complete part per cycle that you can walk away from and go do something else. For a high volume job this is a great method, for one offs it's a pricey investment.
A double angle chamfer cutter could also be used to deburr the back side of holes on CNC operations. Sure beats manually chamfering over 100 bores as a secondary operation.
Thanks for the video! But for me it just seems like a good way to destroy a set of bearings in a live center while risking getting sliced up. With that CNC in the background I would have just made up a vacuum plate from a plate of aluminium and then with an inexpensive vacuum pump you know you have around 14psi hold down. On a disk that big over 800lbs of hold down and it would be fast! If that wasn't an option I'd use a super glue arbor and reduce the risk of flying parts and damaging a live center.
LMW All that for a job that you bid a couple hours on at best ? Good luck staying in business. How is using a live center as he is going to destroy it ? This puts no more stress on it then any other operation .
900 STX putting extreme pressure on a live center will cause wear, I've done it they get fucking hot and have had to change out fucked bearings before. A vacuum plate is something I've used alot and making yourself one when you have time is a good investment. If your making alot of these then CNC will shit all over doing it manually. Just because you want it done cheap is never an excuse to do it dangerously, I've done some dodgy shit in the past to "just get it done" it's not worth it.
Hey Joe, what about using double face tape as your driver medium? Also locating a center point for your circle and rough locating that with the tailstock center before you add the front driver support. I also knock the corners off to an octagon on the saw, doesn't take as long as cutting a round and really reduced the flying triangles of death that trepanning the OD gives you. Just my $.02, would be interested to hear what you think.
I was thinking a similar thing... A light dusting of 3M super 77 on the paper and then letting it dry would give it just enough tack to keep if from slipping, without gluing it to the part or fixture.
Hey thanks Joe for that instruction on a "quick and dirty" method that can be very cost effective when done right. And thanks especially for sharing about your friend Joe...long-time friendships are always the best friendships....sorry for your loos.
You have a very good eye :) Why would you not use instant glue like watchmakers? I guess it saves the clean up and having to heat the part to get it off but it would give a bit more confidence ?
And you’ve got some tinsel for Christmas now too lol. Excellent work. Just wondering would a slip of vinyl or something similar be great as a backing mat? I would think it would make the grip very good.
do that often. had to make rings of 1.6mm brass plate that are split in 2. could not cut the ring after turning so i had to do it in one sitting. made a sacrificial back plate out of steel. stuck the plates on with lock tight green in the press. then did the honors and removed whit mild heat. nothing go flying as long as you cut slow and controlled. trepan the whole lot like that. the slowest part of the job is changing stock and waiting for the lock tight to set off.
Your video is very interesting. Im training to be a machinist and I never do pressure turning. Quick question: when you were setting up the square piece of sheet metal to the driver which is seated to the live centre on your tail stock. I noticed you ‘eye-balled’ the workpiece to ensure concentricity. How do you know it is completely concentric without using a dial testing indicator to set this job up on the lathe.
What about turning a long giant bar of aluminum to the correct width, and then cutting slices off of that like salami with a band saw? I am sure there are various reasons that won't work at these tolerances you need, but I have seen people mass produce gears that way. Cutting the teeth long ways, then slicing the bar like salami in to gears.
That would work if the parting of the slices could be controlled and produce the desired finish. Ideally, a laser or waterjet cut blank would be ideal.
yes this is the video i think you meant. i didnt have a name for this operation but pressure turning sounds good. i have done this a lot on the lathe. i always need a thin round circle andhad no idea on how to achieve it and then it donged on me make a samitch of metal with my cheese in the middle great video
Painters tape and super glue work really well. Of course you would have had to turn a large piece of round stock to act as a sort of face plate. The large surface area allows the tape to have extremely impressive holding strength. The glue simply holds the back sides of the tape. I've employed the technique on milling operations several times. Never a bad result. Give it a whirl some time if you haven't tried it.
I had been cutting discs on a lathe from square plates in-between the jaws, until a new machinist told me about pressure turning the other week. So much easier 🙈
Hello there Cap'n Another superb "How to" Video. Guess just as many ways to solve a machining problem, with due care. Seeing this was relatively thin material, or even thicker, could we would not do this with our Iscar left facing Parting Inserts which would cut the same as Your HSS ground bit ??? Just a thought. Thanks for showing and sharing. We never stop learning at 69 on. ATB aRM
Oooops. Sorry. It should be Right Lead Angle cutting Insert similar to Your Bit. Has a Width of 3mm which will be perfect for these sorts of jobs coming in from the front of the work. aRM
I'm guessing productivity. This is a very quick setup. I might be tempted to superglue the clutch material to the driver and backplate though. That loose paper could get annoying after 20 parts.
