Member postings for Chris TickTock

Chris

You really should get yourself a copy of the book written by Joe Martin who was the owner and real driving force behind Sherline, although not the creator.

The book is called 'Tabletop Machining' ISBN 0-9665433-0-0 and covers exactly the points you ask.

The book is a complete inspiration on using small machines.

I visited the Sherline factory about 6 years ago, they make a superb product that punches way above it's weight.

If you are going to buy the book, you can borrow my copy until yours arrives.

Regards

Barrie

Barrie, very kind offer, let me have a look through my books first which as I have not needed to to date I have not read. My policy is never borrow a book as it lead to falling out if it gets forgotten, but your a mate for offerring.

Chris

Chris

This is the one I made. No plans just made it up as I went along!

If you have a look on the JB website there is a link called"Applications for toolholders" This will help you visualize the various types and what they can be used for.

I find the SDJCR type useful for smaller stuff.

I have no connection to the company, It was recommended to me on this forum and I found the quality and service to be excellent.

Incidentally, what workholding method are you using on the Sherline? Collets or chucks? It has no bearing on your question, just curious.

Steve

As I have little experience it would be silly of me yet to say I plan to use a given method. However I have 4 jaw and 3 jaw chucks also collets. As I understand things certain sizes / shapes require one or other I will find where one or another is needed. Any pointers always gratefully received.

Chris

The SCLCR code is

S Screw to retain insert

C Shape of insert

L Holder shape

C matches relief angle of insert

R Right Hand

You then get 06 06 which is a square 6mm x 6mm shank

Then say 100 which is the length of the tool.

Note the Glanze site uses the same ISO code for an 8mm shank holder for all their cutters

Further homework here

Jason you've done this before.

Regards

Chris

Stresses will generally be the same for all grades between black and bright.

Silver steel is a specific type of carbon steel, having a certain composition, carbon percentage and ground finish. There are many other steels with different cabon contents and usually drawn or black finishes.

If you look at the price list from M-machine that Adrian took his link from and go down to about page 20 you will see that this supplier states the type and finish of their various steels so you know what you should be getting.

If you want to post the link to your local supplier I'm sure we can point you to what you need.

Thanks Jason my local supplier only states black and bright and is none responsive. I have emailed my order to the Link kindly given and think all is well as at the moment it is solely for EN1A.. However i could do with a hand getting the right holder with the insert recomended. I think I will be working with right handed tools and I guess that also applies to inserts.

Regards

chris

Edited By JasonB on 16/08/2019 15:11:12

Christopher,

Re the inserts for aluminium. The main difference is that the surface is polished smooth instead of being just the sintered rough finish. Aluminium has a habit of welding itself to the cutting tool tip, this effectively makes the tool blunt till it is scraped off. The rough surface of **M* inserts makes it happen a lot faster than the smooth surface of the **G* inserts. The **G* inserts can be used on ferrous materials and may produce a better finish as they can be sharper.

I would still keep using the **M* inserts for general ferrous turning as they are cheaper, keep the **G* for finish cuts and Aluminium.

I did not see it mentioned in the thread, but EN specifications are the "old fashioned" names. You may also see the steel quoted as.

Free cutting EN1A = 230M07

Leaded free cutting EN1APb = 230M07Pb

Mild Steel EN3b = 070M20

There are lots of others, this is a good intro then just to scare you the European BS EN

Adrian

Thanks Adrian good reply will digest it slowly. I am obviously still a bit confused as I though silver steel was a high carbon steel yet when I just went on a metal suppliers site they offer separately silver steel and carbon steel...anyone help with this?

Chris

ENIA can come in both bright and black forms but if your supplier does not state the exact metal spec then goe elsewhere or ask. For practice get bright.

Bright bar is also known as cold rolled which means it goes through the shaping and sizing cold and the scale drops off. Black is known as hot rolled so shaped hot and a scale that is "black" forms as it cools. Bright can has some stresses in it but for turning don;t worry about that now.

Thanks Jason I have picked up on the stresses but does this apply as well to the EN1A graded stuff as well as the ungraded bright?

chris

Have a look on eBay - or **LINK**

I found a world of difference when I went from a local supplier to a good EN1a source.

I've just discovered Mallard and they are very reasonable.

They are inserts MADE FOR CUTTING aluminium, not actually made OF IT

On my Sherline i use inserts & hss, the ones i use of choice by a long way are the aluminium inserts. DCGT070204, CCGT060204 & TCGT1102040, these are fantastic inserts for Alu, brass & steel including silver steel. They give a finish like you would,t believe, i also use DCMT & CCMT inserts as well sometimes. I use a QR tool post on my sherline & 10mm insert holders mainly + a couple of 8 mm insert holders.Re taking fine cuts & precision with inserts, this is where the aluminium inserts really shine ( no pun intended on surface finish ), you can take cuts that fine that the metal comes of not as swarf they are to small to be called that really. You see more shinny particles glistening in the light rather than swarf falling, more of i dust coming off. Of course you can also take much deeper cuts also with the aluminium inserts, these are very sharp inserts indeed & care needs to be taken on catching your fingers & hands on the tool.

Edited By Martin Hamilton 1 on 16/08/2019 11:21:53

With no radius if you magnified the cut surface it would look like a very fine screw thread being made up of a Vee shaped helix and could feel quite rough but the pointed corner of the tool will easily cut into the material* . Another problem with a pure point is that it would wear very quickly and also be prone to damage particularly on brittle carbide tooling.

On the other hand a large radius will tend to flatten out the magnified form so you will get a smoother finish. however the larger contact area can increase the chance of the tool deflecting slender work and if deep cuts are taken you can also start to get chatter along the increased area being cut. A more rounded tip will have the advantage of being more durable.

Another thing to consider about a tool with a rounded end is that when working into a corner the face and edge will not meet at a crisp angle, this needs to be taken into account if something is going to be slid onto say a spigot turned on the end of a shaft usually by chamfering the mating holes edge. Where parts will be stressed it is an advantage to have a rounded internal corner as it helps to dissipate the stresses thus reducing the risk of a fracture starting in the corner.

* the angle of the tool also plays a big part in what the surface may look like. Taking the thread example if you had a tool with a large clearance angle behind the cutting edge it would form more of a Vee than one with a shallow angle that tends to flatten things out in much the same way that a rounded corner will do. Luckily the C*** inserts being discussed give a shallow 5degree angle behind the tool so you get the best of all the available shapes. The down side is that in some situations this can prevent you getting to the work and a more pointed shape will be the best bet such as when working close to a tailstock centre where a DCMT tip and matching holder are ideal.

So it's a case of weighing up finish, durability, work in hand, access, etc and picking the best combination for the job.

I get excellent results on my Sherline with silver steel using CCGT inserts with a 6mm JB Cutting Tools holder.

Also with Arc Euro 6mm HSS Co5 tools.

They also work great with brass and EN1A.

With small stuff, It's important to get the centre height bang on.

Edited By Steve Crow on 15/08/2019 17:37:05

Hi Steve what exactly is a 6mm JB Cuttings tool holder and where can i sorce one from. The main problem identified with inserts according to a poster here is fine cutting are the CCGT insets up to precision work?

Chris