HSS vs Carbide | Tooling For The Mini Lathe

One area of machining that can get a little overwhelming at times is tooling. For tooling nowadays there are two types that are common, high speed steel (HSS) and carbide insert tooling. Both have their place in the machinists workshop and have their own advantages and disadvantages. This is a very brief break down of the two types of tooling and their advantages and disadvantages and my experience of using them on my sieg c3 mini lathe.

I am sure that I have skimmed over some details here and there and not ever situation and material will turn the same as it turns on my lathe, but I hope the information in this video helps. I put all the information I wish I was told when I first got my lathe into this video.

Cheers

[robertburns]

With 40 years in the business this is the most complete video I've ever seen on carbide in the small shop. One thing I might recommend if you haven't tried it is 5 or 10% Cobalt cutting tools . I highly recommended them. Slightly more expensive than high-speed but hold their edge three to four times longer.
P.S. I just subscribed.

[aceroadholder]

I've found that brazed carbide lathe tooling is the best of both worlds. It is important to buy name brand brazed carbide and avoid the Chinese mystery tooling. The name brand stuff is inexpensive and with a 6" silicon carbide grinding wheel for $20 you are good to go. There are 3 grades of carbide tooling. One is for iron and the other is for everything else. The third is good for everything but is a little more expensive by a few pennies. I have brazed carbide lathe tools that are 40 years old and still have plenty of life in them.
You can grind your tooling as needed just like high speed steel and when it's chipped or damaged a few moments with your green silicon carbide wheel has you back in business.
In a commercial business insert tooling rules. Time is money and you can't waste time sharpening tooling by hand. Just as important changing a damaged or worn out insert with a new one often means the tool setting is very close to the insert just removed.
Cheers from NC/USA

[shanemeyer]

I sharpen all my carbide tooling except for some finishing ones with large radiuses and they cut like butter but will always be more prone to chipping and cracking, this is minimized with not backing out of cuts and making sure to smoothly and consistently pushing through the cut

[halflife]

GREAT summary video! I couldn’t agree more with everything you said as I’ve discovered using both types. 👍 I would have added that with carbide you need to nearly double your rpm & feed rates, as well as it not requiring coolant which is a huge benefit on the cleanup perspective not having to clean up spun cutting oil everywhere. Also would have been worth mentioning about the different carbide coatings which mate to steel vs aluminum.

[philoso]

One difference between HSS and carbide most hobbyist and myself didn’t know about was the (work stress) a lathe or milling machine can endure without excessive body twist and therefore chattering.

HSS cutting edge can be grind very sharp to reduce work stress in small / hobby lathe perhaps fitted with an upgraded motor.

On the other hand carbide cannot grid to equal sharpness without risk of chipping off at its cutting edge. To avoid chipping, carbide were manufactured with a designed radius (dull wo/apex) at its edge.

Caveat? Carbide cutting edge will glide / skid on the work surface at a load normally applied with HSS, unless we deliberately force / dig it into the material. That cause a small / hobby machine chattering.

Chattering? Can be improved with rigidity in the system beginning from removing free play at sliding junctions. This causes assembly difficult to slide. Remedy? Reduce profile ripple on sliding surfaces. How? By counterfeit scraping referencing to a flat certified granite block.

If chatter persist? Admit we are a creative hobbyists with a flimsy machine. Use HSS with coolant, reduce feed rate, reduce advance rate between each pass, change spindle rpm and continue creative.

[dodgydruid]

My first set of tools for my 1930's mini lathe cost me about £5 off of Aliexpress, brazed carbides and as long as I don't sweat them too much produce a very nice finish, better on softer metals but slowly handles steels with care. Got a sweet set of spot drills off there too for couple pounds, an angle protractor for about 80p and a very nice quick change tool post set for £20 coming with 5 tool holders incl a boring bar holder and a parting blade holder but they skimped on the grub screws so changed them for longer high tension allan bolts on the standard tool holders as the brazed carbide's are quite small, ideal for a mini lathe. I haven't fitted the tool post as yet because to do so, I have to pull a stud from my crossslide or make a sleeve nut to fit the existing stud. Next job is to try and find or build a transmission axle, I have en route a jack shaft with suitable 3 step pulley, waiting on finding a suitable tall mount to mount the pillow bearings to hold the jackshaft which will give me three speeds from my motor. I have watched most of your videos and learned so much too.

[peterfitzpatrick]

I have 8mm HSS blanks that have been used & reground for 20 years... 😏

I'm not a big fan of carbide unless I'm machining something unusual... particularly when running a small lathe, you can grind a fairly aggressive rake which will DRAMATICALLY reduce the horsepower required to make the cut... 😎👍☘🍺

[smallcnclathes]

Because my small lathes are cnc and used for production, I use carbide inserts. AK style inserts for aluminum are not the only inserts that have the really sharp ground edge. I use the Sumitomo FC style inserts which has the ground edge but a rake of 15° which makes the edge a little stronger. There must be other inserts around that are similar, these are called "Finishing" inserts, so intended for light cuts, which are probably still pretty huge by are our mini lathe standards. I would suggest that metal removal can be much the same, as the spindle can be run flat out with carbide, for most of my work the maximum of 3000rpm is theoretically too slow. As a guide anything non ferrous below 30ø can be run at 3000rpm and for steel at 100m/min surface speed (which fairly conservative and a low figure) anything below 10.5ø can be run at 3000rpm.
I must admit though that in my larger manual lathe, I do like moulded inserts. They deal better with any operator that is a bit clumsy and bangs the tool into the work, not me of course! LOL

[crazypj]

One major advantage of coated carbide I've found is machining aluminium.
There is far less edge build up compared to HSS. Saying that, I still mostly use HSS on 6061 but it does need lubricant ( usually mineral spirit) which can sometimes be messy. I have also used cheap synthetic motor oil thinned down which works very well (diesel also works well and isn't too smelly)

[freeloader]

Just getting into machining with a little lathe I picked up and this was very helpful. Looks like I need to grab some HSS

[HM-Projects]

Nice video for folks starting out. You can use the sharper AK geometry in carbides. eg. CCGT060204 AK H01

[Ketis]

More spindle rpms and no need for coolant are couple advantages that carbide inserts have against HSS, but yes HSS has its place. I prefer carbide inserts.

[mikerr]

This was a great video, thanks!
I don't think I can manage a grinder in my apartment so I was wondering what to best equip my mill with.
I think I'll stick to carbide for aluminum but after hearing about HSS being sharper, I think I will use that on my plastics.

[nicolashuffman]

Stefan Gotteswinter showed on his channel that while mass produced carbide is not as sharp as HSS, you can grind it to be just as sharp. Just use diamond abrasives and don't breath the dust.

[fna-wrightengineering]

Great video, full of good information.

There are a couple of improvements I'd suggest for your mini lathe, that will further improve accuracy and surface finish.

First and foremost: That tool post. I had one just like it... It's a quick change, your tools are "always" on center, and the price point makes it VERY tempting... But after using it a few times, I can honestly say that those cheap aluminum tool posts are absolute garbage. First, they're aluminum, so your rigidity is handicapped right out of the gate. Further, the tolerances on the dovetails are terrible, so repeatability in X, Y, and Z is utter trash. And again, rigidity suffers greatly. Do your lathe a huge favor and upgrade to an Aloris-style 0XA wedge-type tool post. They're a bit more expensive, but the Chinese clones are actually pretty damn good, and the increase in rigidity and repeatability are MORE than worth it. I can't recommend this enough... It's probably the single best improvement I've made to my mini lathe. Deeper depth of cut, and improved surface finishes are a tangible result.

Second: Inserts. Inserts meant for aluminum are where it's at for these small lathes, even in steel. They're much sharper, and have a positive rake angle. This reduces tool pressure considerably, which helps a great deal with the inherent lack of rigidity these little lathes have.

Another easy thing that can improve rigidity is adding locking screws to the compound and cross slide. Simply drill and tap a hole for an M4x0.7 socket head cap screw between the first two gib set-screws of each slide. Tightening the screw locks the gib against the dovetail, and you'd be surprised with the difference this can make with rigidity.

Optionally, getting rid of the compound completely, in favor of a solid tool post block, is also a great way to improve rigidity, though this requires some effort and tooling to make. Again, though... It's well worth it for the deeper depth of cut, and better surface finish.

Keep up the good work. These lathes get a bad rep, but they can be capable little machines, if you put in the work. Great to find someone else making good parts, and good content, with a mini lathe. Cheers!

[myth-termoth]

I believe the trick with carbide inserts in a small machine is to use the type of insert called a finishing sharp. Unlike standard tooling, made for deep fast cuts, finishing sharps are optimised for lighter work.

[jimmycote]

just try CARBIDE TURNING INSERT, ALUMINUM with ebonite pen blank and it work pretty well when we turn nylon, acetal.

[EngineerSteve]

Good video with helpfull information, underrated in views tbh...

[TABE-O]

Thanks mate. Just what I needed. Where in Sydney is a good place to buy?

[ChriFux]

i mostly use inserts made for cutting aluminum. those are sharp as and you can also cut steel with em, and the resulting finish is excellent.