Full Circle

[Niels Abildgaard]

Chuck Fellows started a thread on homemade tangentials

http://www.homemodelenginemachinist.com/showthread.php?t=10702

with a round HSS toolbitt

http://s192.photobucket.com/albums/z195/cffellows/8b077207.jpg

In the mean time I have had fun making tangential holders

http://imgur.com/U3sK5bE


From left they are
Three press manufactured(4 hours making time each)
The first uses a 3/16 Crobalt bit that has one of its corners modified to 85 degree to go easily into corners without grinding top face with a rather obscene angle of 30 degree or more.Next is 5.3mm carbide treated same way and last is a rather expensive triangular carbide bitt.
The middle one was a test to make a holder even faster and is described somewhere in original thread. I do not like it.
The three last are the Rolls-Royces .First two are wire-sparked by a professional and the uttermost rigth is made by me as pure lathe work.
As You can see it is using a round 4mm discarded carbide endmill free and of good parentage.
Idea is that Carbide is nice but beasts to regrind for tangentials
For cutting steel I very seldom(never?) cut more than 2 mm deep and a 4mm round is apprecially less grinding than the 5.3 mm square one.
It works well on my extremely rigid Boxford lathe,but I really do not know if it is an advancement of the art.I have no QCTP with carbide and cannot really compare.It is 25.48 mm top to bottom at the moment and can easily be taken down to 22mm,or shimmed up of course.If someone want to try it and write a few words here it is up for grabs.

Kind regards

Niels

 

[Niels Abildgaard]

M8 screw and 4 mm round carbide are not made for each other.
Annoying as cutting was good.

 

[deverett]

Have you seen the Carboloy version of a tangential tool using round tool bits?
The design looks pretty old, but easy to copy.



Dave
The Emerald Isle

 

[Niels Abildgaard]

Hello Dave and You are absolutely rigth.
Next one looks like picture and is easy to make.
It it still worth a try to reuse scrapped 3,4 and 6mm carbide mills

 

[Niels Abildgaard]

Being widover I can rise at 5 o clock and make things.
First of the wasted carbide mill holders was tested.Interrupted cut,900 rpm,2.5 mm depth of cut and feed per rev 0.0012 inch (whatever that is).
4 and 3 mm is waiting for some EBay used endmills.
As a young man I did not think much of handsawing to within .3 mm of wanted dimension.
Am surely getting older as You can see.

 

[Niels Abildgaard]

Has got some 3 and 4 mm carbide endmills and tested new holders to day.The 6 mm thing was tested yesterday.
The 3 mm ran at 900 rpm 36 mm diameter with a depth of cut 1.5 mm and axial feed of 0.002 inch per rev with no problems at all.
The 4 mm 900 rpm 40 mm dept of cut 2.0mm axial feed 0.0033 and transverse 0.0008 beginning to chatter in axial mode and tool slipped unles really thigthened.

I will concentrate on 4 mm in future as lathe is not strong enough to use 6 mm
to limit and the ease of grinding difference between 3 and 4 mm is insignificant.
But I need a bigger screw for clamping.

Second picture was swarf after first 3 mm test run.
I tried to video with one hand phonecamera and swore never to try that again.

 

[Niels Abildgaard]

My Lumia 1020 makes nice videos so let me try.Some patience please.
I have reground the 3 and 4 and 6 mm round discarded carbide endmills and put them in their respective holders..First picture shows the 3 mm after having cut 1.5 mm deep(facing ) with a feed of 0.1 mm at 700 rpm on a 40 mm piece of some martensitic stainless steel scrap.430 FMC/S43020/1.4104



Video 3 mm tantool

[ame]https://www.youtube.com/watch?v=SEetSzkiK_E[/ame]

The 4 mm was tried afterward at 2 mm depth and began misbehaving ,shattering at a feed of 0.065 mm

Video of 4 mm round Tantool
[ame]https://www.youtube.com/watch?v=6svB_iTyxIU[/ame]

The 6 mm endmill was misbehaving at lowest possible feed 0.02 mm and 3 mm depth.

To check on that I used my normal square(almosst 5.3 mm carbide holder and got sligthly better result.But not much

http://www.homemodelenginemachinist.com/attachment.php?attachmentid=78919&stc=1&d=1442426342

Morale of the story: Nothing beats a discarded 3 mm round endmill for pure removal rate and surface was like ground in all cases.

 

[Niels Abildgaard]

I have 6 tangental holders surplus to requirement seeking new homes.
Lathe shall have at least 25 mm from top of compound to centerline.
That is Southbend 9 inch ,Boxford,Hercus etc
First from left carries a non describt 4mm HSS in a round hole and can be had for postage.
Second is a holder with a reused 6 mm carbide endmill and can be had for postage
Third one breaks the inserted 4 mm endmill if You thigthen it senseless.If not it cuts very well.Postage only.
The three on rigth side carries a piece of 3/16 Crobalt for which I want 15$/10£ plus postage.
Gone within a week or scrap

 

[mcostello]

Something to add to the post, I turn abrasive plastics now and then. They are rough on HSS, so I sharpened a plain square nose carbide tool bit to tangential suited angles. It does not worry about the plastic, has it for lunch easily. It might not take a very big cut in steel as the joint is now in shear, have not tried in in anything else but plastic.

 

[Niels Abildgaard]

Something to add to the post, I turn abrasive plastics now and then. They are rough on HSS, so I sharpened a plain square nose carbide tool bit to tangential suited angles. It does not worry about the plastic, has it for lunch easily. It might not take a very big cut in steel as the joint is now in shear, have not tried in in anything else but plastic.

Sounds like advice from an old man will not be quite out of place.
I have made a lot of tool holders and think that I keep three .

http://i.imgur.com/1VjMSlS.jpg

http://i.imgur.com/iyr6LSC.jpg



The left one uses 3 mm discarded carbide endmills and cuts stainless steel at alarming rates.
It is very easy to regrind;not because it looses its edge,but the 430 FMC material builds up.
If this was a real production problem I would use the CCMT holder with Lamina Swiss inserts coated everywhere.
Regrinding an unusable endmill is cheaper than buying swiss inserts.
For alu,non glassinfected plastic etc I will use the pressformed holder with modified 3/16 Crobalt bitts.
One side has been ground so that active cutting corner is 85 degree.It does not need to be ground with the rather obscene angles
of the commercial Diamond tools.Good for durabillity of cutting point.

 

[Niels Abildgaard]

A friend has a Myford and I made a Tantool with 3 mm round carbide.Heigth of holder body is 16.41 mm.
http://imgur.com/TREAJAH
http://i.imgur.com/TREAJAH.jpg


[ame]https://www.youtube.com/watch?v=3j00T-fhvvc&feature=youtu.be[/ame]

 

[Niels Abildgaard]

The most used tool on my lathe is a 3 mm round best german carbide.
Chuck was right,round is best.
For cornerwork I have reground some 2 times 2 mm best German to have a 85 degree corner.
I can supply 3mm round 60 mm long for 5£ and almost square 2*2 for 10£
The holders are not difficult to make within 5 to 10 hours.
A better resolution picture

http://i.imgur.com/bceGPwQ.jpg

and

http://i.imgur.com/bqBhT9p.jpg

 

[tornitore45]

I notice some reference and pictures to use of a drill bit as tool.
Drill bit shanks are soft to allow a grip by the hardened chuck's jaws.
No good for tools. The businesses end is hard, but not round.

End mill shanks are hard because are held in a collet that grips on a wider surface than 3 jaws or are held in a End Mill Holder which depends on positive engagement rather than friction.

 

[Niels Abildgaard]

Hello Mauro

The 3 and4 mm drills shown was just testing for size while waiting for scrapped carbide endmils from E Bay.
At that time I did not know that 3 mm is best for my lathe and I did not know that I can buy unused ,polished carbide from Germany for less than broken endmills on EBay.

 

[tornitore45]

I can buy unused ,polished carbide from Germany for less than broken endmills on EBay.

A good thing to know.

I had a hunch the drills were just for show.

 

[Niels Abildgaard]

A short video showing cutting 40 mm stainless with a 2 times 2 mm almost square stick of carbide

[ame]https://www.youtube.com/watch?v=DeFLeNPhqDY[/ame]

 

[Wizard69]

Niels, looks like you need a chip breaker.

 

[Niels Abildgaard]

Niels, looks like you need a chip breaker.

A VFD controled feed rate (Like on Schaublin and Hardinge) will be a better solution,but I am going to try a loose chipbreaker.