A really daft question

[PeeWee]

Hi All,

It embarrasses me to ask this question but I have no choice.  I have the Warco WM-280V-F lathe and seem to be struggling to slow down the auto feed to gain a really smart cut.  
I am on switch setting C from the options which is the slowest I can find.  Those of you who have this lathe or other make any help gratefully received.   I know the answer will be obvious but I just have a mental block.  

Its not really mattered whilst making some tooling, but I am now wanting to start on some engine projects.

cheers

[lordedmond]

I  have not got that lathe but would it not be quicker to ring Warco ? to get the answer as to the best feed




as a side note I have been tuning some EN3B 4.5 inches via with the feed at its slowest 0.002 per rev using carbide at 350 rpm the finish was awful , increased the feed to 0.008 per rev finish superb   chips came off blue though

what I am trying to say its not the finest feed that gives you the finish, its the correct feed for the job they are not the same try what bogs recommends a round tipped profile tool , he swears by they



Stuart

[Jasonb]

Position C will give the finest feeds.

Have you got the finest setup on the gear train on the banjo, mine came set up that way but it's possible you have another configuration.

You have got the righthand  of the three knobs set to drive the feed rod (one with the groove) and not the leadscrew as this would in effect give you a fine screw thread.

When doing facing cuts the finest 0.00075" / rev can be a bit fine on some materials but I've not had a problem getting a near mirror finish with the lathe

Assume sharp tools and on ctr height.

Jason

[PeeWee]

Stuart,
i have a round tipped profiling tool so will try that.  i have spent an afternoon with speeds and feeds to work out a combination, like you say its the combination.

Jason, PM sent.

cheers
both
Ian

[lordedmond]

Ian

the most significant factor in getting a good finish is as you have found out its a combination of rpm and feed, but a very important factor is the the tool profile not the shape its the point radius . the tip radius must be larger than the feed per rev.
the tip radius must span more than the feed per rev , ( that why the round profile cutter works so well )

the other most impotent question is what is your material is it EN1A , it may have been sold as such but it may be just BMS or worst GCQ ( good commercial quality ) in other words unmachineium , get a good supplier who understands what they are selling

as I mention in my first post EN3B its tough but it turns well not as good as EN1A leaded

don't forget to finish on our class of lathe HSS is still the best to take off that modicum and leave the finish OK carbide need to be worked hard fast and heavy cuts to perform


Stuart

[PeeWee]

Hi,
its supposed to be EN1A,  i am off to locate some HSS cutters/blanks to compliment the glanze cutters. 

[picclock]

Carbide is good for removing material volume, but to get really good accurate finishes HSS is the tool of choice. You can't take small cuts with carbide and get a good finish (well I can't  ). When there's about 5-10 thou to go to the required size, swap it out for HSS. Sharp tool tip with small radius, say 0.5mm. Fairly high lathe speed and very slow feed will give a satin like finish which can be mirrored with minimal application of very fine emery paper. Use lard as a cutting lubricant.

Only other thing to watch out for is low tool overhang from the holder (say 2 or 3mm), a toolholder which is not height adjustable (set tool height with shims) and good tight gibs. I've even removed the compound from my lathe and replaced it with a solid steel block to improve the stiffness at the tool tip. If its allowed to flex even slightly you will not get the eveness of finish.

Accuracy of final size is best controlled with a dial indicator on the crosslide and a micrometer for diameter, depending on how accurate you need the size to be.

It should be very easy to do with EN1A

Good luck

picclock

[PeeWee]

Hi All,

Well I have ordered some HSS blanks that should arive in the next day or 2.  Once correctly(ish) ground hopefully i will see an improvment.  though one key factor here is i also need to improve myself and only practise can do that. 

[Jasonb]

The Glanze ones should be fine if they are the CCMT type, (not so keen on the triangular ones) I use them a lot on the same machine and only revert to HSS on small delicate stuff or where I don't want an internal radius.

I think the feed rate was too low for carbide as I said in my PM.

J

[picclock]

@ jasonb
I can't agree with your post. I've been turning steel and mystery steel for over a year now (so still a relative newbie). Whilst you can get acceptable finishes with the best carbide its still not a patch on HSS with lard. Its almost impossible to to take a cut of less than 4 thou with carbide, yet with HSS cuts of <1 thou are easily achieved.

So while carbide is great for removing loads of material, it really sucks at getting the final finish with accuracy. Without accuracy, you can use carbide to get to within 10 thou or so and have an adequate finish (hot chips driving it hard) but for chasing the last few thou its hopeless.

So please do not take offence at this post. The info is won by many turnings and much experimenting with lubes, tools cutting angles etc.

Best Regards

picclock

[Bogstandard]

Picclock,

Its almost impossible to to take a cut of less than 4 thou with carbide

Actually, at one time I would have agreed with you fully on that score, but it has taken a couple of years to change my mind.

In fact the time it has taken to get my then new lathe fully tuned in and under my total control.

I am now just like Jason, unless I want a real sharp corner, I stick totally to ccmt inserts, and I sometimes work down to 0.0002", in all sorts of materials, and I can achieve the angel hair shavings that were once only the domain of razor sharp HSS tooling. With some of the junky materials I work with, HSS wouldn't even get a sniff in before it had a flattened off cutting edge, even with super tiny cuts.

After trying a few different insert makes, I have now settled on this one, not only about the cheapest you can get, IMHO, the best general purpose cutting ones as well for my particular setup.

http://cgi.ebay.co.uk/5-kennametal-inserts-CCMT-06-02-08LF-KC9125-47-/170625659989?pt=UK_BOI_Metalworking_Milling_Welding_Metalworking_Supplies_ET&hash=item27ba14f455

But one thing you must remember, I have a fairly beefy lathe, something like a minilathe, and you would be onto a hiding trying to use carbide tipped to get super fine finishes.


John

[Jasonb]

As bogs says you CAN take small cuts with insert tooling but it does depend on the lathe if its got any flex in it then the tool will just push the work away. As my lathe is the same as Peewees he should be able to get similar results. I would say 98% of the turning you can see in this album was done with carbide inserts, do you think the best I have worked to is 0.004"

What lathe are you using as this may explain why you can't take a fine cut, oh and another 25yrs turning experiance

Jason, no offence taken

[Stilldrillin]

I use brazed carbide tools for all the general machining in my mini lathe.......

Take "half a thou" cuts, no problem! 

Not happy with indexables though..... 

David D.

[Bluechip]

Take "half a thou" cuts, no problem! 



David D.

Me too !!

It's putting "4 1/2 thou" back on that I have grief with ...   

Dave BC

[Bogstandard]

Dave (first one),

They are a different type of carbide, and can be refinished to a very sharp edge, in fact to almost the same state as HSS. You should really purchase them for the type of metal to be cut, as there are several grades used for the tips. They are perfectly fine to use on all machines.

J&L stock them reasonably priced in their catalogue, and also give the information as to what type is used for which materials. I used to use the blue for general purpose and red for the harder steels and materials. The sky blue pink ones that the Chinese versions come in is no guarantee of the grade of carbide used, I think they are painted that colour just to make them look pretty. You need to traul thru their catalogue to find out where they are.

http://www.mscjlindustrial.co.uk/CGI/INPAGE?PMPAGE=catalogInfo/catalogInfo.html

For CC tips, which in laymans terms are moulded, and don't have the super fine sharp edges, then rigidity and grunt is what is required to get them to perform to the best of their ability. There is a very fine line about what size machines they should start to be used on, and in my personal opinion, a 9" lathe is about the smallest. Smaller than that, they don't usually have the rigidity or power, and if carbide needs to be used, then the best bet would be the brazed on type that you use.

Just a personal opinion, gathered by experience over the years.


John

[Stilldrillin]

Dave. (second one).
That DOH! moment......  

John.

Thanks for the link!

I handled my first Sandvic replaceable tip knife tool in 1961, and loved it! Obviously, this was on grown up, production machinery.....

For lots of years after that, I was a miller. Until retirement, and relearning turning with the mini lathe.

You're right.... The carbide tools (red, and blue), work very well, and sharpen very well with a diamond disc.

The very few indexables I have, just don't work for me...... Guess it must be the lack of power/ rigidity, as you say.  

David D

[Bluechip]

Hi Dave SD

Red Carbide tools ??

Like this one attached?   1/2" Sq. 102 CINTRIDE ENGLAND ??

Never used them 'cos they wont fit my QCTP. 

But I have another toolpost, cobbled up by myself which does. 

Got about 15 or so, still boxed. All sorts. RH, LH, etc.etc. Never been able to sharpen them very well, even on a green grit wheel.

So, what's the business with a diamond wheel ??

Dave BC

[Stilldrillin]

Dave.
About 1/2 way down the page.  http://madmodder.net/index.php?topic=963.30

And here.     http://madmodder.net/index.php?topic=850.30

David D

[Bluechip]

Dave SD

That was 2009 ?? Has he got any left ??  ( was 2009 AD I presume ... )

How do you go on with the round-ended tools ?? About 4mm dia IIRC.

Should look at them really.

I used to try to sharpen them on a green wheel, but always seemed to get the '6" wheel curve' (?) on the front of the tool, which seemed to screw up the angles.

Really good when new, but after I had a chew at them ... well .... downward spiral, road to ruin  etc. etc.

Was once told to do 'em on the side of the grinder, but I don't like doing that. Worked though. Can't be right can it ??


Dave BC
 

[Stilldrillin]

Dave.
I was there t'other week, he had some......  


Round end tools?  I just round end 'em.....

As long as the wheel curve is from below the cutting edge, it's clearance......

All apprentices are told NEVER to use the side......... Until they know what they're doing/ have gained a bit of finesse......
Then the side is used, as necessary...... Really, it's what works for you that counts!

Yer know me Dave. I can show better than tell..... Remember clocking the r/table?
Get yerself over here for 1/2 an hour, sometime. Soon!  

David D

[Bluechip]

Hi Dave SD

Good on yer -- will do.

Need my 7mm die anyway ... well not really, a mate wants me to do some bit for his Bing carb...

As if I don't have enough disasters of my own without importing his... 

Dave BC

[Chazz]

A little OT (ie feel free to water cooler this) , if you asked my machining Guru 20 years ago about switching from braised\ground tooling to inserts you'd be fired and chased off the property! 

Today? Not does he only swear by 'new' tooling, he gave me a 1/2" Kennametal, 2 flute end mill and a couple of 1/2" CCMT inserts to try out.  So I asked him, "At what speed should I run the Mill at?" 
He said "Well....How fast can your Mill go?"
"2400 RPM" I replied, he said "Go for 1,800 to leave you a little torque on that little puppy and obey the 1/3 rule on cutter size vs. cut width\depth." 
"So, what about feed rate?" I asked, he said "How fast can you turn the handle?" 
Well, needless to say, I was\am making a new cross-slide screw (6mm? to 7\16") and a QCTP base, both the cross-slide screw support bracket that mounts to the apron, and the QCTP base riser were machined from 4" Dia 4140 steel......guess what......as to the 1\2" mill, I'm still rough cutting with it 6mos later  soon to be retired, however, the current replacement cost (In Canada) is about $24.00 and come up on sale for $12~13.00. 
As to the inserts, right off the get go there was an improvement in finish, however being a rookie I could not figure out why I went from making a beautifull .002 thread to a pretty .0015 thread?    Well, Guru gave me 2 lessons (so far) concerning insert tooling, Lesson Number 1, No Matter What "They" Say, there is no cutting tool (insert) 'Truly' ready to go, he took a fresh insert (New-out-of-the-box) and we did a rough cut on a 3\4" dia chunck of MS stock (looked threaded), he then took the insert to the 'Green' wheel and a couple of quick touches, then he pulled out a fine India Stone, gave the relief edges a few deft strokes, re-set the tool and voila, near mirror finish.
As to using the side of a grinding wheel, if you have a dedicated grinder (like my Guru has) they have been using the same wheel for over 2  years (remember a production shop) with no issues.  Dedicated is the point here, all the 'green' wheel EVER gets used for is carbide inserts and the amount of pressure and grinding time are next to nil, if you are grinding for more than a second or two you have most likely ruined the insert or ground off the coating. (again we are talking 1\2" bits not a 3" wood chisle)
Lesson 2 (so far) Coated inserts will\can build up a 'smear' of material during cutting that may require a clean up with the India Stone' on the cutting edge and  I cannot stress chip clearence vis a vie carbide, that is they can easly chip due to their stiffness if swarf gets between the work piece and the tool.

My 2 cents and cheers,
Chazz

[Bogstandard]

Chazz,

A few years ago I saw an article in a magazine where a chappie had made a honing guide, similar idea to the ones used for honing wood chisels, for use with a diamond lapping plate that did just what you mentioned, sharpen up the edges a tad. He even got it to put back the tiny radius on the ends.
He reckoned he had very good results with it. I think the article might have been in the early editions of MEW. I will have to root thru to see if it is.

I have a cunning plan.

Over the last year or so, I have gathered together and bought all the bits required to make a vertical rotary water dipped lapping system, to do the same sort of job. But I am looking at restoring dulled carbide inserts, rather than treating them before use.

But to my way of thinking, they would only be able to be re-used for fine finishing or with softer materials, rather than the heavy cutting exercise they usually get, because of the weakened razor sharp edges.

It would only require twenty inserts to be brought back from the dead to pay back the outlay I have already laid out.

I already hand lap the tops of the round tips used in my profile cutter on a water soaked diamond lapping plate, but the restriction then is that the top rake is gone, so can really only be used for brass etc, but at least I get three or four re-laps before they are ready for throwing away.

I have had some good test results by using a horizontal water cooled sharpener/grinder that was used in the cutlery and blade sharpening operations in higher class restaurants. I used it in my model boating days for grinding flat or bevelling the edges of small 1mm thick glass sheets for making into windows on models, but it was a bit precarious getting the angles correct, because I was hand holding the tips.


Depending how my tuit list goes, will see whether I start on the machine this year or next.



Bogs

[picclock]

@ JasonB, Bogs
I'm amazed that you can get such fine cuts with carbide. I would like to see that with my own eyes to find out what you are doing that I am not. Assuming we are talking steel here. 

I'm using DCMT inserts purchased from Glanze, I also have some triangular ones and the squarer shaper line yours bogs but smaller. I have noticed that some inserts (DCMT) are better than others from new, and of course its all about the edge. I can't think that the CCMT edges are going to be much different to the DCMT ones.

Not sure if the lathe has that much effect, because if I can cut 0.5 thou with HSS why can't I cut it with carbide. The only reason is that the edge is not sharp enough. Having said that I'm only using a 7x14 minilathe, tapered head bearings, metal head gears modded with reduced gearing for higher torque. The compound has been replaced with a solid steel block which makes it more rigid than the standard offering.

I'm currently fitting a 0.01mm dial indicator to the crosslide permanently (well, with magnets so I can remove it) because with normal magnetic holders they always seems to be in the way. This easily resolves 1/2 a division giving me  .2 thou resolution.

I'd like to get to Harrogate but its about a 4 hour trip each way for me which is a bit far.

Best Regards

picclock

[Bogstandard]

Picclock,

I honestly think you have answered your own question.

No matter what type of bearings or how tight the gibs are and how the machine is set up, your machine really has too much inbuilt flexibility to take advantage of the higher power requirement of the ccmt tips.

As has been said before, compared to HSS and brazed tips, moulded tips are actually nearly blunt. So when your small lathe tries to push them thru the metal, the machine flexes and the tips deflect away rather than cutting. Because we have larger more beefier machines, the tips are forced thru the metal without being deflected.

When you start to go into the deep physical and maybe chemical properties of cutting materials with ccmt tips, the metal isn't actually cut like you would normally expect it to be, but actually almost peeled off the surface. I only know about this because of articles I have read, but don't ask me to explain it, as it was way above my head.


Bogs