Member postings for Chris TickTock

Hi Guys,

This is almost an embarrassing question to ask, nonetheless I think I will, so forgive me for my stupidity in advance.

Question I need to turn down a 9.5 mm Dia, 75mm long piece of EN1A steel in my Sherline lathe to mostly 4mm. I have put it in the chuck then thought should I center drill the end or not. Basically is there a rough guide to what can be held in a chuck without the other end being supported. There surely is a table somewhere saying e.g. 3mm Dia only 4 times its Dia sticking out unsupported?

Or is this another instance of its up to the machinist, which is all well and good once you have sufficient experience of machining.

Chris

Edited By Chris TickTock on 27/08/2020 13:54:36

Thanks Dave,

It would be easy for me to just blindly accept the use of Silver steel or EN24T both are up to speed. My issues are understanding why and that eventually makes for a better understanding and hopefully result. Totally agree with your analysis but it is good now to know I have EN24t as a viable alternative.

I am guilty of not reading my books as often as I should but will make an effort. Will also see if I can get the book you recommend .

Thanks to all posters really helpful especially converting tensile strength to Rockwell as an approximation.

Chris

Hi Guys,

I am trying to find a machinability index of steels that include EN24T and Silver Steel. I have so far failed miserably.

Silver steel in its annealed state comes in at around 27 RC but cannot find what EN24T would come in at. I realise there are other factors that affect machinability but these points are a good starting point.

Anyone help with these couple of points?

Chris

Hi Martin,

Can you clarify whether you are recommending the use of EN24T over the use of Silver Steel and if so why. I am becoming a convert as both silver steel and EN24T are reputedly not the easiest steels to machine but EN24T as you say can be left once machined without further heat treatment. Or have I got this wrong?

Chris

Hi David, at the moment just accessing alternatives / possibilities.

Chris

Hi Guys,

If I buy EN8 or EN24 steel how easy is it for the man in the shed to harden and if necessary temper these metals. If for example EN8 comes as normalised can it be machined then hardened easily without expensive equipment. I have tried to find the answer to this but all I find is can be hardened by flame or induction process and tempered at approx 600 to 700 degrees C for a period dependent on size. My thoughts would be holding such a temperature would be quite an accomplishment for a period without an oven.

I fully understand you can get variants of these steels but some basic pointers would be helpful. my aim is to look at the best substitute to silver steel should I wish to. Are the steels I stated more practical to use for a one off pinion on a clock than EN1A which is readily machinable though not as strong.

Chris

Martin,

My understanding is the rpm recommended is for each individual cutter on the commercial cutter. Whilst it is obviously the case for commercial production a commercial cutter would be more durable and cost effective this does not apply for a man in the shed replicating a single wheel or pinion. A fly cutter is made easily given practice, is cheap as chips to make and is sharpened each time before use so a better result can often be achieved.

Moving on to the choice of metal if not using silver steel. This is a bit more confusing for me so maybe others can chip in. i note Cousins and John Wardle sell pinions made from EN8/EN8DM. Maybe they come from the same supplier, maybe they are trying to replicate age characteristics?

Could anyone compare EN8 to EN24T in terms of using it on a small lathe for making a pinion with a fly cutter?

Chris

Edited By Chris TickTock on 26/08/2020 10:38:23

Nigel,

This came as news to me. But after having a quick look it appears you are right that heat treating steel (and other metals) can indeed cause dimensional changes. However I would need to know if the changes are of such a scale to cause ilikely issues.

Thank you for posting this as I need to be aware.

Chris

Upate: Making a 90 degree cutter from HSS was much easier than I thought . Will see how it cuts but it opens the door to making numerous other cutters. Picture attached

whilst on the subject I came across a video of a man cutting a lantern pinion. he was cutting between 2 shoulders with what looked like a wider parting tool. I should add the distance between the shoulders was approx 15mm so not possible I think  with right or left handed as you can imagine. Can anyone help out with the shape of a cutter to make as in diagram.

Chris

Edited By Chris TickTock on 25/08/2020 12:01:47

good point..thanks

chris

Thanks for all posts, points I have picked up on are;

If using Silver steel anneal it first to be sure it is at its softest.

If you have as I do a rotary table you can run more passes at a slightly different angle.

Do not use abrasives on machine (My comment: but if you do use a cloth to protect ingress)

Because the final cutter is machined HSS is not to my knowledge normally used to make the fly cutter. However I am minded to attempt cutting HSS as Jason says using initially the grinder and then my new bench sander where I have more control. How easy it is to get such a small cutter by hand will be interesting to find out. This HSS cutter in theory should cut a chamfer and be easily modified / sharpened for another pinion.

I would also add I am keeping in mind the use of EN8 to use which is I believe machinable and can be through hardened.

Chris

Thanks Baz, I am making a pinion purely to know how to and in doing so trying to look at best options. The lantern pinion is for another day. I am told making a pinion from high carbon steel is difficult especially with a fly cutter. Part of the fun is finding the best way to tackle a job, given I am a man in his shed economics comes into play.

Chris

Jason,

No need for me to make the holder as I can use the HSS blanks I have in the fly cutter holder. I think this may be the easiest solution ...thanks for post.

Chris

Edited By Chris TickTock on 24/08/2020 18:07:24

Edited By Chris TickTock on 24/08/2020 18:07:47

Hi Guys,

           Using a fly cutter to cut a clock pinion is not an easy task on higher carbon steels. I am told it is a good idea to remove as much metal as you can before using the cutter.

Using a slitting saw achieves some removal.

However what I am looking for is an economic way to remove metal after the slitting saw to leave a chamfer which the pinion cutter can hopefully finish.

There are several possibilities and I have a rotary table so can rurn the stock as needed.

My ideas off the top of my head

Dremel diamond disk used on Sherline mill. A purpose made fly cutter just for hogging out. A chamfer bit (but is expensive) A double angle bit (is expensive), a rotary burr.

What do you more experienced guys suggest (apart from buy a Thornton's cutter).

Chris

Edited By Chris TickTock on 24/08/2020 17:13:55

Edited By Chris TickTock on 24/08/2020 17:14:18

Edited By Chris TickTock on 24/08/2020 17:14:52

Jason can you confirm just in case there is something I don't know that as a slitting saw is a circular saw the teeth must point in the direction of rotation (clock wise when viewed looking down from the front on the Sherline mill).

I have read so much negative stuff on using slitting saws that I am checking everything before starting. Things like climbing up the work etc and not straight cuts do little to comfort a novice to the procedure.

Chris

Hi Guys,

My aim is to cut approx 1.5 mm deep cuts in a 6mm dia by 20mm long piece of mild steel that is part of a longer thinner length of stock to enable clamping.. This is just practice to see how I get on. The purpose is to learn how to remove as much metal as possible before using a single fly cutter to make a pinion. Single fly cutters are fine with brass but wear rapidly with harder steels.

So my question is:

Can anyone / does anyone have experience on the best set up to use a slitting saw for this purpose. I should add I have several thicknesses of saw and have learned to go slow and plenty of lubricant. I will be using the Sherline arbor which has no key way.

Chris

One of my many failings to date (which I can now see and am trying to address) is the pace of my accumulation of knowledge. By this I mean I see something interesting find out about it make notes with the intention of making it then see something else that diverts me. mostly I have made that I have intended but not in the case of the square broach or tapered square punch.

With regards to a square broach if my memory serves me i was looking into ways of making a key. The tapered punch was looking at a way i read on the clock forum of enlarging a hole for a particular function, I think for making the small 'counting' cam on the strike rack. On first thoughts using a tapered square punch sounds decidedly risky as opposed to using a file carefully. However if I remember the person advocating this was a English clock maker with a good reputation so my thinking was it is worth noting.

Thanks to all posts, as always noted. Bob 's method as stated is helpful. As my lathe and mill  Sherline I could either do the same or even use index blocks and the mill.

I am improving but as my machinery / accessories grow I have had to slow things down to make more comprehensive notes so when I go back I fully have documented all relevant detail.. All going well and

As I have said before no hurry,...it is but a pleasure.

Chris

Edited By Chris TickTock on 23/08/2020 09:48:08

well spotted Jon

Chris

Thanks Guys, all helpful

Chris

Steve,

A big thank you, I am just ordering the lathe attachment to make the MT.

Chris