CNC lathe, HSS parting blade as a parting tool & tool overhang. Carbide vs steel and aluminium.
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- Опубліковано 16 лип 2024
- Parting tool overhang can be a real trap. Lets have a look at how this can happen and perhaps go unnoticed. From the standard 4 tool tool post that comes with most lathes to the ubiquitous Quick Change Tool Post, that everybody wants to fit. We look at single piece parting tools and HSS steel blades and holders. Shows a single piece $25 eBay parting tool dealing with 2011 Aluminium and S1214 steel. The eBay tool is a MGEHR1010-1.5 which was $25 on eBay including 10 inserts, almost half the price of a HSS blade and holder.
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"I'm just a draughtsman" statement there is very telling I've worked with engineers over the years that would tell you that they are no more than a glorified apprentice, whilst being very very very good at their jobs, I've also worked with people who will tell you that they are technicians without being able to work out one end of a multimeter from the other. Always love your videos keep up the good work.
Well I finished my apprenticeship in 1969 and became a draughtsman, so I do not attempt to be classified as a proper tradie with many years of experience on the tools. Started with cnc back in 2005 and never used a cnc larger than those I have now. My first one, an Emco had an 80mm chuck.LOL Thanks for your comment.
@@smallcnclathes All the good people did a proper apprenticeship, I've learnt in life to listen to all the people that don't say they know what they're doing, and ignore all the people that say they do. I look forward to more videos.
Been at this for over 50 years. Although carbide insert parting tools work well , so do properly handled HSS tools at a much lower cost. I am still using the HSS blade I got decades ago and there is no sign of it wearing out in my lifetime. At work they go through those inserts AND the holding blade , like candy.
I spend 10 years machining nothing but 304 and 316 stainless with HSS tooling and it was fine once you get familiar with it. I resist all carbide insert tooling because I feel like its like having an employee you have to pay, like renting your tooling , whereas HSS is like owning it.
Carbide is fine/essential for production but for my personal shop it is reserved only for tougher jobs. You are never "down to your last edge" with HSS toolbits.
Hi Bill, I have not spent much time in a general engineering workshop, spent most of my working life as a draftsman. When I got into cnc, I was happy to use inserts as I had a lot of learning to do and that was one area that was easy to pick up. Inserts are, as you say, quite expensive, but most of my work was non ferrous so my inserts tend to last a very long time. Thanks for taking the time to leave your comment. Input from folks who know what they are doing is always welcome.
Flipping from 90⁰ to 67.5° and 45⁰ is quick on my tool post. I often do it with a parting tool to do other small cuts. Especially delicately facing or chamfering.
Well done and well share informative keep your eyes open see what you are dealing with on your machine or lathe. Thank you, Lance & Patrick.
Thank You
Only time I think hss parting tool is actually the best choice is for plastics especially nylon due to the really sharp positive rake you can grind, all other time inset tools all the way
Hi Nigel,
As always a good video... Kurtis a CEE is very good indeed...
Take care.
Paul,,
its the grind geometry thats the challenge of HSS.
watch the insert... see how it makes the chips into little barrels? theyre shorter than the width of the slot being cut, so they dont jam!
usually the hss calls for a slight angle on the tip, to "part the work off".. i find doing that just makes tools make nasty crunchy sounds and send things everywhere. think about it. the reason is so damn simple...
whereas splitting the tip, so the swarth "caves in", you get the same barrel effect as the insert makes... sort of. thats the idea anyway, two cutting edges that fold the material inwards, rather than straight back. then you just split it off center for the same "clean parting" effect, one hangs out a fraction more.
super fine stones sharpened to a an obtuse angle, do the tip, do the top, gives you front clearance and the top/side rakes. a little squitty 1" stone has a small enough radius to make nice back rake without nearly removing the entire top... set the dremel up in a psuedo "tool grinder"...
yes, you can do a normal cut with a parting blade, as long as the side clearance is sufficient, and you got a decent side rake. it usually isnt. most people just wack em on the grinder and forget that the swarth is as wide, or WIDER than the slot...
one of the most important and overlooked aspects of turning is CHIP CONTROL.
For production, which is what I used my cnc for carbide inserts were the only way to go. I think in one of my videos I show those barrel type chips. Thanks for taking the time to comment, it is appreciated
@@smallcnclathes yeah, i wouldnt be too keen on hss for parting under power... then again, when you do get them to run nice... oh my. nah. keep it manual and resist all temptation to flick that lever...
still, ground inserts find a place on some work. razor sharp edge that doesnt mind interrupted cuts and severes plastic properly... seldom use but i keep a box of t,c,v**W on hand...
wish i could get stellite on an insert...
Bought one of those eBay tools, . Looking forward to trying it out.
Please let us know how it goes
Parting is such sweet sorrow? (Had to do it) Learn a little every time. Funny how the basics of machine rigidity is so simple and yet it escapes so many people.
And in that you can include the manufacturers of mini lathes and mills. My Hercus weighs in at around 150kg probably two or possibly up to three times the weight of a Chinese min lathe. There ain’t no substitute for cubic inches transfers easily to pounds or kilos when you are looking for rigidity. Not only does making it lighter use less metal, but also makes it cheaper to freight around the world. Olfoundryman has a Cincinnati mill that is old, I think it weighs in at around 3 tons. It is a very rigid machine. LOL
Parting should not be the drama that it becomes. Before I started with the Hercus, I would not have dreamed it can be the way it is for me now.
@@smallcnclathes I am with you all the way. I have two 2.5 tonne lathes and a bridgeport style Elliot Millmor that's almost 2 tonnes. It's hard to beat these machines. The Milling machine is from the early 60's one lathe the mid 50's and the shorter Colchester is from 72 if I remember correctly. The Colchester Mascot is a unicorn. Larger motor and works compared with the ones afterwards. It was a university/government collaboration with Colchester to make a very high quality lathe. My smallest lather is just short of a tonne. Nothing CNC. Yet. Why for I watch what you are up to and learning along the way! I'm just a Cabinet Maker after all.
a few of the more NEW common (grizzly, craftex) lathes share the same cross slide
the weakness is in the material AND design of the compass/protractor mount for the tool post.
theres a guy who made a tutorial of his remade compass using basic 4140 with only slight changes to final dimensions and the rigidity difference was huge...
also some of these cheaper chinesium qctp's use a very flexible post that should just get swapped for a hardened bolt
Kurtis is making exelent stuff on Cutting Edge Engineering Australia Channel, so go and take a look what he is making, and remember to watch his videos all the way to the end because he also shows all his funny fu..ed up clips.
It is certainly a great channel to watch.
When using the blade type on a small lathe resulting in a large overhang, it works better if the tool shank is reduced in size to bring the blade closer to the tool post making it more rigid..
Fkng outstanding!👏👏👏👍👍👍👍👍👍👍
Thank You
i still use the HSS cutoff blades, but only because thats what ive learned on and not had many problems. getting a good grind on one is fast and easy and profiling for facing / grooving or even a turning path is par for the course.
steel brass aluminium no problem, copper and some stainless can be finicky.
edit:
I am optimistic in experimenting with one of these in future tho
Thanks Kazz, I know they are in use, but beginners could take a long time to reach your skill level. I just find the type I use work well for me, all my tooling is carbide inserts as I need the repeatability.
@@smallcnclathes oh i absolutely agree with you on that!...you gotta use what you know and experiment in the off time and be particular when you do so.
I'm totally keen on getting one of these newer carbide setups like you use because of your videos...
i just know my setup is very different than your and will take some old fashioned crash and burn experimenting to get it right (so its gonna take a bunch of time).
i may not even get them to work well for me...but im optimistic..
stopping to hand sharpen and re-calibrate is motivation killer to say the least
Glad I decided to always wear goggles when running my lathe. My self-ground parting blade shattered and threw a fragment at my eye. Looking to buy a parting tool now!
Did I convince you to not buy a hss blade?
You could use a machinist jack to support the HSS cutoff tool, but that is like putting a band aid on a broken leg. Get the right tool holder and a carbide cut off/parting tool, you will respect yourself in the morning.
I think I have seen a video of something very similar to that. Thanks for your comment
Some people suggest replacing the compound rest on those chinese lathes with a solid block of steel or cast iron. This of course means you can't turn tapers, but the increase in rigidity is massive.
Sounds a reasonable swap to me, as long as the compound can go back on if required. Thanks for your comment
Unfortunately my job has a ancient Victor 1660 lathe and I just barely got rid of the hss part off tool. It was horrible
Thanks for your comment
I hate those parting tool as well. Some are not sitting even vertically in that holder, they tend to lean at an angle against the holder, so one side would have a friction.
Thanks for your comment
thanks Mate, was trying at 20rpm no lube 4 inch 4140, have 550x2000 Cazaneuve, will go try 320 with lube eh
I would try from around 250 to 320 at that diameter. Certainly more than 20!
Need lube!
Kurt at Cutting Edge Austrailia has just recently updated to QCTP on one lathe and since decided to probably change all. FYI. Anyway I agree about the Hss blades, they are a waste of toolholder, as a hobbyist nearly all my tools are from ebay/aliexpress. I have only 1 tool that is pro made and I cannot tell the difference on my small lathe.
Bound to happen I guess with the passage of time that a comment could become incorrect. The QCTP is saw though, was actually one very robust unit. Not many of us have lathes big enough to hold it. LOL
@@smallcnclathes CEE use the Dorian precision quick change tool post from Livetools. Dorian have a range of sizes which would probably fit your lathe. Only down side is --- with quality comes cost.
@@johnspathonis1078 I have a cheap QCt which is fine for me. I notice Kurtis still uses the standard tool post quite a bit. Thank you for your comment
Nigel, just checking to see if you're alive and kicking? It's been awhile and I sure miss your videos. I hope all is well.
Hi and Thank You for asking. My channel views are going down the toilet, so not very encouraging. I have been waiting to see how low the views would go. They seem to have bottomed out now. I have a few videos in mind, one is almost finished and ready for uploading. It is me attempting to put a camera on my turret to follow the tool, I hope it will be of interest. I am doing a job at the moment which will also be another video. The lockdown restrictions where I live, are not easy to live with and it feels like they been in place forever. I can hardly move in the shed due to bags of swarf which I have been unable to get to the scrap dealer! Otherwise keeping well thank you.
Just released a video! Let me know what you think of it. A bit different for me.
Number #9 created chips are what I was taught are the ideal. However your from Australia, so their called #6 !
Also, your NOT supposed to "turn" with a pocketed carbide parting insert. Too much side pressure will push the insert out of it's pocket. G'day Mate!
I have not found that to be the case myself. A friend with no turret on his small cnc uses a Sumitomo Profiling insert for all his turning. The geometry is different to make side cutting possible. This video (not one on mine) shows it being done. I think most manufacturers have videos on YT showing grooving inserts side cutting. Thanks for your comment
I found one of mine in which I mention being surprised to learn special grooving inserts were made to cut sideways ie profiling. ua-cam.com/video/tiFUZxXXzdI/v-deo.html
The large QCTP's that fit a 7 meter lathe are pretty rigid. Also the price tag for the toolpost and say 25 holders would be pretty high. It may be not worth it to buy. The rigidity will ultimately boil down to the lathe and its foundation. Maybe with a very large long boring bar like 10"+ stickout it would be different story even with a large QCTP
His previous lathe is actually the one to which I refer, it is a much smaller lathe, but still pretty huge. He does a lot of work on mining machinery.
@@smallcnclathes I watch the channel too 😅
Apart from being very skilled he is an amusing young bloke.
@@smallcnclathes sure. Actually the only real benefit of the QCTP after all is that you can save the tool offsets to the tool library of your DRO and know without measuring between tool changes where you are. The tool height is the same for all the OD tools that have similar size shank so you don't need to shim each one differently if the tools are chosen with that in mind
Hi Nigel, thanks for the tip. I was quite surprised that a small change such as moving the toolpost over the mounting axis would make a huge difference.
Perhaps it's something a keen eyed draughtsman can spot quickly ? 😉
Also link to Cutting Edge Engineering Australia channel ua-cam.com/users/CuttingEdgeEngineeringAustralia
Thank you for supplying the photos.
My friend I have an accusize carbide parting tool and I can't get it to cut through brass. It starts out fine but getting to the end it ceases to cut
Please help.
Whar rpm are you using?
@@smallcnclathes hard to tell. It didn't come with an rpm gauge
@@mosfet51 Two possibilities, you need higher rpm OR the tool is too high. Check your tool centre height first and see if it improves
@@smallcnclathes I've done higher rpm and centered the parting tool. I even went slightly under center.
No better?
1:14 I bought a parting tool just like this one but with a replaceable carbide insert. Tried to use it to cut through a 21/2 in schedule 40 steel pipe and my 7x14 mini lathe couldn't do it. It chattered badly and when I applied more pressure it caused the belt to slip if I applied more power or stalled if I kept the same power. Blue chips were being cut but I gave up. What are the parting tool limitations for a mini lathe??
I think a reasonable rule of thumb is about the bore of the spindle times 1.5. So headstock bore of 20, no more than 30 diameter should be attempted. I have quizzed a number of friends and they agree with that sort of figure. How wide was the insert on the tool you used?
@@smallcnclathes Thanks for the quick reply! The parting tool is 1/2 in wide and 3/8 in thick. Using the stock indexible tool holder. I had to extend the cross slide as far back as possible and then the compound on top as far back as it would go to just provide enough clearance for the 2 1/2 in pipe. Wow!
I meant the width of the insert. Small lathes like narrow inserts, I use 1.5 or 2.0 as a maximum. Wide inserts need more power.
@@smallcnclathesOk. It's about 2 mm or 1/16 in.
Me too facing same issues with parting tool, often ending with broken inserts . I have used from 1 mm to 2.5 mm inserts but all failed. nowadays I am scared to do parting on my mini lathe. I am just a hobbyist.
what surprised me is usually everybody suggests slowest rpm for parting job so I usually do with 300rpm, but in this video it was suggested 2500rpm. I doubt my lathe can even do that speed which is a 3 feet lathe running with 1 hp motor.
A fair number of former soviet union machinists persist in using non quick change tool posts and its not because they couldn't get them if they wanted to. That should say a lot.
The only really nice thing about hss is it needs less tool pressure to cut
I will really take some convincing about that. The inserts for aluminium with 20 degrees of rake are extremely sharp. One of my parting inserts is actually called a low cutting force insert, the rake on the front is 30 degrees. Pretty sure I have a video about rake reducing power required.
I think hss wins on its being able to be ground to do things that would hard for the average operator to grind in carbide. That would be the only time I use it and of course in twist drills. Thanks for your comment, they are always appreciated.
A blade style parting tool must be sharpened properly.
A bench grinder with a dressed wheel, and an angled steady rest to ensure proper relief usually does the trick.
"Hot Tip"
Pun intended.
Keep a cup of water close to keep it cool.
You must not change the color of the steel when sharpening it.
Otherwise its case hardened, aka useless.
I use to run Davenport Screw machines, and they all used blade style cut-offs.
But they had a carbide strip on the top.
The one you have is only good for low carbon steel, and most non-ferrous metals.
With spindle power of 1/2 hp, 4140 is the toughest material I have attempted. Mostly work brass. No way could I be bothered with hss blades. If insert is blunt, replace and off we go again. Thanks for your comment, always good to hear how other folk do things.
Fill it with water and set off the explosive in the centre
I think this comment must belong on another video. Makes no sense to me at all.
@@smallcnclathes yes, it was a comment I left on the last beyond the press video. I have no idea how it ended up in here
I think there is a place for HSS especially with the addition of 5% cobalt to the HSS. Machinists (professional or home grown) have to machine all types of materials. I believe HSS is much better for plastics as they are sharper. Also using an insert type tool holder with HSS can lead to isuues such as the top rake angle. Insert parting blades have the top rake angle built into them. The better designed HSS blades have ground bevels on the top and bottom and have tapered sides. These should only be ground on the front face (not top) as the holder should already has a 5-7 degree rake back angle. I suggest your viewers watch Joe Pie who demistifies the HSS parting blade.
Thanks for your comment. I just think carbide is much easier to use than HSS. I have had no issues parting plastics with carbide, just changed the parameters to suit. There may be a place for HSS parting tools, but I never found it, perhaps because of the production type bias of my work.
@@smallcnclathes Thank you for your reply. Can you please be more specific about these parameters. Eg. what parameters would you use for parting off a 50mm rod of UHMWPE. How would you ensure there was no nib left on the parted off part?
@@johnspathonis1078 I don't part that big and usually only acetal and nylon and pvc. Recently found I had to peck acetal when normally I never peck when parting. My parting tools are from Sumitomo and Kennametal, I have not had any issues with them. If folks want to use HSS, that is fine with me, just not for me. My experience is doing production work that suits the size of my lathe which is 100mm chuck and 1/2hp.
@@smallcnclathes Oh sorry my fault for not looking further. I mistakenenly thought you were talking about a workshop lathe. I will shut up now. 🙂
Hi John
No need to shut up. LOL My turning experience is pretty much limited to work I can do an my small lathes. Often when larger work came in, I simply passed it onto others. 1/2hp can be a bit limiting at times, the same as 1" through the spindle.