Thread: carbide tooling

hi i have a hercus 9 inch and i am sick of always sharpening hss cutter and not getting a smooth finish my questions are does carbide tooling stay sharper for longer and does it produce a smooth finish also what size would i need to fit my hercus with lanyer tool post thanks andre

If you are using HSS in a Lantern type tool post I would suggest you keep using the HSS.

If you decide to go Carbide are you thinking of Cemented Carbide Tools or Indexable Tools.

You will have to measure the width of the slot in your Lantern post and see if you can get suitable tools that will fit,if not you will have to machine the tools to fit the slot,you would probably have to use 3/8" or 1/2" shank tools.

Will the Carbide stay sharper for longer (maybe maybe not),depends on how you use the tool,whether you chip the cutting edge, bump the tool and chip the edge,can also depend on the grade of the tip and the material you are machining.

The finish you get from Carbide can be dependant on the RPM,FEED,DEPTH OF CUT,if the tip suits the material you are machining.

You may be better off making a FOUR way tool post or some other design that will allow you to use tools without having to modify there shank.

If you have a 4 Jaw chuck and Drill Press you can make your own FOUR way tool post for less than $30,00,if you dont have a Drill Press you can use a portable drill just mark your holes and drill square.

hi i am thinking of using index able cutter and i have already started to make a four way tool post

When you make your Tool Post ,I would suggest you make it to suit 1/2" tools.

That measurerment is from the base of the tool shank to the top of the cutting tip,that way you can use any tool shank size upto 1/2" without any problems.

The Depth of the opening in your tool post where the tool sits would be good if you could have it 5/8".

The Height of the opening would be good if you could have this at 3/4".

If and when you purchase your Indexable tools I would be looking for tools that will take ISO tips,some of the Cheaper tools you can buy require you to only purchase tips from the manufacturer of the holder,rather than from the manufacturers of tips.

2nd the 4 way toolpost but I'd be surprised if the Hercus had enough power and speed to successfully run carbides to give a good finish.
When you say the the tool doesn't stay sharp for long, what sort of time are you talking about? How smooth a finish do you want?
Without anymore info, perhaps the job material is not suited to a good finish. Perhaps your HSS bit isn't ground quite right for a good finish. There are just so many variables. Good HSS, ground correctly and set in the toolpost correctly, should have a reasonable life. Again depending on the material, cutting speed, coolant, etc etc.
Can you post some pics showing your tool bit, the setup and the material.

regards
bollie7

heres a couple of links to making your own tool post, I made my first one like this with the slot cut with13mm end mill
Quick Change Toolpost for Small Lathes
and then later i made some tool holders like this but still using the original column
http://members.optusnet.com.au/clear...s/article2.jpg
this second one is a bit harder to cut the piece out where the clamping bolt goes but i did it free hand on my metal cutting bandsaw
the 50x 25 mm bms came from bohlers ( see if you can get an off cut rather than them cut it its less expensive) i had a lot of trouble getting my lantern type holder to stay firm but these tool holders work well and its good practice
as for the carbide tip holders
the elcheapos the ones i got the tips kept moving but fixed it with better quality tips
suggest you get name brands or maybe a kit from h&f
boring bars i got from internet single ones seem ok
all use iso tip numbers ( more studying for you )
hope this is some help from what ive learnt so far
john

Personaly, I wouldn't bother trying to use carbide tools on a hercus lathe. The Hercus doesn't have enough power to utilize them. If you stall the lathe (and you certainly will) the carbide will chip badly or shatter. You are far better off to use HSS with Cobalt and grind the tools with precision. I use 3/16" HSS with Cobalt on my Myford Super 7 and it lasts well when roughing. I sharpen it and hone the tool for the finish cut/s and I get perfect results. To get a great finish, hone the tool before you use it. The honing must also be performed as accurately as you can. What material are you trying to machine? Let us know and I can give you more details on the tooling.
If you make a four-way tool post to accept 1/2" tools (5/8" is much better) dont forget that the dimension begins from the centerline of the lathe and is measured down toward the cross-slide.
The other members have already offered advice about rpm's, tool setup, material, coolant, tool shapes and these items have a huge affect on the final finish and results.

Kody

HI i had a look ant my tools i have a have found few welded on carbide cutter but i must not be grinding the hss tool right ( now thinking about it i a was not) so does any have instructions on how to properly sharpen hss steel. also i am not sure what type of steel i am machining on the recipt it just says 33mm polished bar all the best andre

There's an excellent document from Southbend called "How to grind lathe tools"
Available at a number of sites, here's one.

Check out youtube too.

Wotcha welder, welcome to confusion, here's my dit, for what it's worth
Don't worry about speeds and feeds, just kick the gearbox about till she feels right, as we say on m/bikes
Carbide bits are automated mass production devices, run on high speed lathes with flood coolant, they are not ground and can be blunt, frankly not for us.
HSS will cut near anything and will do so at slow speed
Most poor finish on our small lathes are simply movement, could be tool bedded on a bit of swarf, loose gibs allowing backlash 'hum', suspect toolpost mount
Good luck reading tool grinding, that S'th Bend post is brill, just make absolutely sure the only part of the tool that contacts is the edge, so long as there is a wedge somewhere behind that edge it will cut
It's all practice, you have to do something tween getting up and going to bed
If you're not on the steep part of the learning curve you're wasting yer time on the planet, so good luck to you, we've all been confused and some of us will admit it, go for it bonny lad

I have HSS and Carbide tools at home on my small (10x24) 1hp lathe with QCTP. The best finish I have ever gotten has been using carbide tools to cut large HSS drill bit shanks down to 13mm. When cutting mild steel, the best finish I ever achieved was with HSS, but I only did it once. In terms of averages, I currently average a better finish using carbide than I do using HSS. Im typically working on sub 25mm stock, so I run the lathe pretty fast (1500 - 2000rpm for carbide).

I have read every article you can on the web about sharpening HSS, yet still cant grind a tool thats good enough for a nice finish (by nice I mean non striated, even, and with a certain amount of sheen to it). I reckon its one of those things where I need someone to actually show me how to do it before I stand a chance of repeating it. I also notice lots of the pro HSS guys here turn at very low speeds, with flood coolant. I have not tried this yet, but look forwards to doing so. Im keen to master HSS sharpening.

"Most poor finish on our small lathes are simply movement, could be tool bedded on a bit of swarf, loose gibs allowing backlash 'hum', suspect toolpost mount"

I second this opinion too, and im almost certain this is half my problem, but I cant rule out toolbit sharpening as I have no way of telling if my toolbits are ground OK to begin with!

Brendan when you next have a play try droping your RPM with the Carbide,I dont have the high RPM that you have,and as others will say you need High RPM for carbide I dont have a problem using them at the Hercus top RPM for my model of 700RPM.

I turn a lot of High Tensile material and Cast Iron as well as the occasional Aluminium,Brass and Bronze.

I use the Carbide for 2 main reasons,the type of material I machine plus the Diameters I work with,any thing from 1/4" through to 8".

For me Carbide allows me to run my lathe to its Maximum,and yes I have to adjust Feed and Depth of Cut when it starts to labour.

When you use your Carbide is the Feed Rate adjusted to suit the Nose Radious of the Tip.

And yes I do use HSS,for Form Tools,Screw Cutting,Parting,Finish cuts on Mild Steel and some Heavy Roughing cuts on Large Diameter Stock to get under the Scale as well as some Intermitent cutting jobs.

When you Grind your HSS do you end up with 2 different tool shapes for Roughing and Finishing,what I mean by that is are the Clearance Angles ,Rakes and Nose Radious different or do they virtually look the same.

If you are following a Book or Internet for Grinding Techniques dont concentrate on getting the Exact Geometry that they are asking for,you could end up chasing your tale for ages.

As long as the Basics are there for clearance to allow the Tool to cut without Rubbing it should be fine.

I would suggest that rather than try and achieve the Angles they show concentrate on Getting the Tool shape they show.

There is no Harm in having Larger angles,Clearances or Rakes,experiment a bit and see how it goes,after all most of it is Theory and dosent allways work so well in practice.

If you feel that there may be an issue with your Lathe inregards to finish it would be the FIRST thing you should eliminate.

I have to agree with Pipeclay here.
There seems to be a resistance to using carbide tooling because of bad experiences the earlier days.
Because of later advanced designs, I can use a lapped positive clearance ISO TC tip to take off very small amounts in metal like stainless, 4140, P20, and even chrome bar. And at low speeds with little power.
Sure, use HSS when it's suitable to use on the material (and for some, that's all they need). But don't discount alternative methods when they can be used to advantage.
Like anything, they might be designed for extreme use in industry, but with a bit of usage can be better understood.
Peter

Excellent stuff. I should add if the carbide inset is touched up with a diamond grind you have a very powerful tool at slow speed. Just each time I re-edge one I inadvertently find an intermittent cut and...ping, the bugger's gone.

When you use your Carbide is the Feed Rate adjusted to suit the Nose Radious of the Tip.

No. I basically feed pretty slow all the time. I generally use .003mm per rev for roughing, and .0016mm per rev for finishing (this is as slow as my lathe will go). I take a .5mm DOC for roughing, then .125 cuts or less to get down to finished diameter.

I have been reading the Army machinists guide, and one of the workshop practice series books. They both give similar angles and shapes for cutting tools, however...one of them says to have the tool on centre or 2 degrees above, the other says on centre or two degrees below! Which is correct?

My roughing tools are pointy, whereas my finishing tool has a very rounded edge, I think too rounded really...but this is the tool which got me the good finish.