gr 8.8 ht bolt steel which carbide tip

Don't know who Maureen is but I suggest you check all the usual subjects, bearings, gibs, tool on centre height, etc etc.

Tony

A puzzle? Yeah, but no, but yeah.

Carbine is harder and more heat resistant than HSS, and it's at its best used far more brutally. The bluntness improves edge strength but also suits the rate at which carbide works best. It's counter-intuitive compared with HSS in that improving finish with carbide usually requires higher speed, feed-rate and greater depth-of-cut. HSS tends to improve finish by taking lighter slower cuts.

Problem with Miss Maureen Myford is she's too slow, weak, and bendy to get the best out of carbide, partly because her electric motor is called Weedy Walter.

Carbide produces good results on slower machines but it's a tad harder to get good finish with it: experiment.

The bolt not being fully hardened is a misunderstanding too. 8.8 bolts are tough rather than hard so they can be cut with a hacksaw or filed. However, there's no reason why a steel bolt should machine well. Ordinary mild-steel is a bit soft and smeary, Boron Steels are tough and smeary - an unfriendly material. Pot luck,

Dave

FWIW, from time to time, I turn 8.8 grade fasteners quite happily with HSS tools.

They need to be sharp and on centre height, with a fine feed.

Carbide tips are not as sharp as a properly ground HSS. In this way, they generate the heat at the point of contact to soften the material.

If you must use carbide tips, increasing the speed, so that you are running at about 3-400 fpm may help.

May be difficult to run fast enough if you are attacking a M8 bolt!

Howard

Edited By Howard Lewis on 06/10/2021 11:46:33

So which holder/insert were you using? yesterday you mentioned triangular inserts yet today you post a link to a set with no triangular inserts. Say which it is and I'll point you in the right direction.

The bolts are not hardened they are just made from steel that has a higher tensile strength that is not so easy to cut. If you want to use the bolt as a hob then it will need case hardening but then that's only surface deep and not so good for cutting tools better for wear resistance. better to get a bit of silversteel and make a hob from that that can then be through hardened

Edited By JasonB on 06/10/2021 12:54:48

Most of these types of fasteners are produced by upsetting to form the head. The resulting grain structure in the material will show up any weakness or wrong feeds and speeds in the machining/machines being used to modify them from the "as supplied" form.

Martin C

Not entirely true Jason, if you miss-use the threading inserts as turning tools.

Oh, and then complain about the terrible quality

Edited By Dave Halford on 06/10/2021 15:08:10

JB AFAIK i am using a CCMT 06 02, is charcoal colour not gold

Maureens speed is 723rpm giving ca 150fpm about half whats needed I guess but Mo is limited to 1000rpm by recommendation for spindle bearings. 0.5hp Brooks Crompton motor

I dont have triangular tool holder, is that something I should look out for

obtw I think Ive been down this road before but it seems EB is utterly flooded with PRC offers of complet???? sets of tools and inserts most of which i dont want

AFAIK you cant buy individual tool holders like I want 3 for lh rh centre for a triangle insert say and 10mm (not the more popular 12mm

any suggestions - how i hate abusive EB pursuing profits before public benefit - where have I heard that already

Brian

Edited By brian jones 11 on 06/10/2021 15:33:32

I turn HT bolts or srews on an ML7 every so often - using HSS or carbide tooling, I'll happily use either dependant on the requirements of the job, or even what happens to be in the toolpost at the time..

Hand fed, 5 thou roughing 2 1/2 finishing, top gear Carbide, middle for HSS, this lathe hasn't been used since the weather was hot, everything felt a bit 'dry' and loose..

The tip is used and what was in the tool, likewise the HSS, it did get a quick swipe with a slip.. The bolt looks like a seat-belt anchor..

At various times I've bought single carbide tools and tips from JB Cutting Tools, Arc, APT, Chronos - have a shop around - there's no point 'saving money' on Ebay if what you buy isn't doing the job.. ..life's too short..

Even RDG doesnt offer anything????? conspiracy

It seem the 12mm /1/2" shank size is much more common and to use this with my lovely QCTP I would have to shave off either 2mm off the tool clamp or the cross slide surface (this has already been covered here AFAIK)

The alternative is to make your own by using the other end of the 10mm shanks. It seem possible as i did lower the insert depth by milling the base out which everyone said would work as it would leave the holder weakened.

Perhaps skimming 2mm off the base would be better now Doreen is full of beans, will investigate - another little job to do

Update

Ive just spotted a 12mm holder for R*G QCTP have ordered one, may solve problems

Edited By brian jones 11 on 06/10/2021 17:17:39

Posted by Brian jones 11 06/10/2021 15:24:33

obtw I think Ive been down this road before but it seems EB is utterly flooded with
PRC offers of complet???? sets of tools and inserts most of which i dont want

AFAIK you cant buy individual tool holders like I want 3 for lh rh centre for a
triangle insert say and 10mm (not the more popular 12mm

any suggestions - how i hate abusive EB pursuing profits before public
benefit - where have I heard that already

Brian

Hi Brian,

I buy my cutting tips from Ali*****ss the last set i bought were
CCMT 060204 VP15TF Mitsubishi they are only £2.30 for a box
including the VAT and free shipping for 10 tips and are as good as any
tips that i have had over the years .
If you look around on that site the tool holders are there for probably
less than £8 each.
I can't put up the part numbers on here as they will be taken down, if you
want them send a PM and i will send back by return.

John

Brian, did you even follow my link yesterday to APT? As well as decent inserts sold in two they have individual holders in a wide range of styles available individually.

I would stick with the CCMT and CCGT types rather than triangles and usually the holders are servicable so don't rush to get rid of them without at least trying with some half decent inserts.

I would suggest these for general use on mild steel and cast iron, yes that's almost £5 an insert with VAT and postage but they work unlike the 25p ones.

And these for non ferrous, stainless steel and more difficult steels

If you want a new 10mm sq holder then a RH one will do both turning along the length of the work and facing the ends so a LH is not really needed. You can also get individual 6, 8 and 10mm Sq from the likes of ARC, Chronos and JB Cutting Tools so no one is conspiring against you

And this is the finish with the fine feed and CCMT060208, don't have an Ra tester like andrew but it passes the reflection test at least in the middle (see Martins comment)

Edited By JasonB on 06/10/2021 16:39:04

Edited By JasonB on 06/10/2021 16:41:36

Don’t forget that tool holders are just metal, and can be modified.

My 2 mainly used ones are both larger than ideal for my tool holders, so I chucked them in the mill and removed a chunk from the underside.

Dave

Right on JB got those links, one day I might do a proper turn

Dave not all tool holders are than compliant I see ones from Vevor are Cr Steel

but the problem maybe solved see above

Now Im puzzled by this JB area you saying that there are carbide insert on EB that are little better than butter for cutting steel? Yet there are reputable inserts costing 10x 20x that perform a job ask expected

This implies a massive fake fraud with serious implications

Not quite sure about fakes or fraud - unless of course they are being passed off as a quality brand (and even some of those can be doubtful today what with world-wide manufacturing and selling on of brand names!)

These may just be lower quality items, but at the price they might be good for some tasks and good value as such - just not able to do as well in a more difficult situation.

Well NC I started this thread cos I was having such rubbish results wit a so called Carbide insert. turns out that gr 8.8 steel is notoriously variable and can be difficult but mine was terrible so I doubted my abilites and whether in fact I was using fake inserts

eg you try buying a diamond lapping wheel. It seems most are just rubbish, a few bits of diamond gravel and dust. you have to pay 10x price to get a proper item. yet its all there for the unwary egged on by EBAY

Not all carbide is created equal just as not all HSS is created equal you pays your money and takes your choice.

Some get lucky with the various market places but the few times I have dipped by to they were very poor.

You would only be using fakes if they were being sold as something like a brand name, they may have slipped out a back door, been rejects or simply made down to a budget and the first part of the code eg CCGT060204 is only the half of it there are then many grades, geometries and coatings which a lot of the market places don't either tell you the rest of the code of if they do there is no explanation of what it's designed to cut or what cutting parameters to use.

In other threads you have kept going on about jobs taking a long time so why are you wasting time getting cheap unknown tools and faffing about trying to get them to cut, put your hands in your pocket and get something that is likely to work straight away.

For what it’s worth I don’t think these are made of chinesium or cheese, but the modified quite easily with a quality HSS endmill

Dave

JB its all very well taking the high minded attitude but there are i suspect many of us who dont have your fund of knowledge and experience and WE DONT REALISE WE ARE BEING RIPPED OFF.

Are you in fact saying "dont buy any carbide stuff from EB = its your loss"

I have to say in HSS tool steel I largely get what I expect

Note for twist drills most gold plated on offer are poor quality and wont last long, so buy from a recognised make

Same goes for thread taps, many packs sold are simple carbon steel efforts only suitable for repairing damaged thread in a garage say.

but we know this

unfortunately the carbide world seems 99% fake but people can get lucky with exceptions as shown

Imagine you are sold carbon steel piece for a lathe tool - well simple inspection would show the difference

Try and tell a fake carbide inserts apart?????????????????

I'm saying it's upto the individual if they want to take the risk but don't come here moaning if you can't cut it or make statements that Myfords can't use carbide if you have not tried any half decent inserts.

So why is your HSS not touching your bolt or were you not expecting much from it, there is a reason you can buy a HSS blank for 50p and a decent one of the same size may cost £20, there must be a reason why one costs more than the other

Never seen any gold coated drill bits so who knows what you are talking about but I get very good results with Dormer A002 and A022 TiN coated bits

Carbon steel taps and dies can cut very well, it's down to the quality that one is getting and that is usually dictated by price

is that the royal We as what you say seems to differ from what others know.

Edited By JasonB on 06/10/2021 19:18:24