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Ideas to remove metal before using cutter

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Chris TickTock24/08/2020 17:11:32
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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.

 

hogging out.jpg

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

JasonB24/08/2020 17:22:11
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Simple single point tool in a homemade holder. Tool can be ground from broken ctr drill or milling cutter shank if you don't want to buy a HSS blank. Holder is just a bit of round steel bar, cross drilled for the toolbit and tapped at the end for a lockscrew

photo 90.jpg

Edited By JasonB on 24/08/2020 17:22:34

Baz24/08/2020 17:26:12
642 forum posts
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Try making two angled passes per tooth, this will leave you next to nothing to remove with your flycutter. If it is so difficult for you to make a pinion why don’t you make a lantern pinion instead? Lantern pinion only involves turning a cotton reel shape and drilling a few holes and poking a bit of pinion wire into them.

Chris TickTock24/08/2020 18:07:08
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Posted by JasonB on 24/08/2020 17:22:11:

Simple single point tool in a homemade holder. Tool can be ground from broken ctr drill or milling cutter shank if you don't want to buy a HSS blank. Holder is just a bit of round steel bar, cross drilled for the toolbit and tapped at the end for a lockscrew

photo 90.jpg

Edited By JasonB on 24/08/2020 17:22:34

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

Chris TickTock24/08/2020 18:15:05
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Posted by Baz on 24/08/2020 17:26:12:

Try making two angled passes per tooth, this will leave you next to nothing to remove with your flycutter. If it is so difficult for you to make a pinion why don’t you make a lantern pinion instead? Lantern pinion only involves turning a cotton reel shape and drilling a few holes and poking a bit of pinion wire into them.

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

SillyOldDuffer24/08/2020 19:10:32
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Posted by Chris TickTock on 24/08/2020 18:15:05:
Posted by Baz on 24/08/2020 17:26:12:

...

... I am told making a pinion from high carbon steel is difficult especially with a fly cutter. ...

Chris

In my limited experience high-carbon steel isn't difficult to machine provided it's soft. Usually unhardened when bought I believe, but if necessary it can be softened by heating cherry red and allowing to cool as slowly as possible. To reharden, heat cherry red and plunge into cold oil or water.

The process is identical to Silver Steel, it's just that Silver Steel is formulated to harden with minimum fuss, whereas ordinary high-carbon steel is more touchy about time and temperatures. Only done it a couple of times, but I get the impression high-carbon steel is easier to heat treat in larger lumps, say about the size of a knife blade.

A Flymo Blade might be worth experimenting with because they're probably a plain high-carbon steel. Modern knives and chisels are more likely to be made of an awkward alloy, results unpredictable!

Anyway, not daft to remove metal with brutal tools to protect an expensive one. I've gashed with carbide, coarse files, cold-chisels, and an angle-grinder. An angle-grinder isn't suitable for fine clockwork, but it is useful for quickly hacking small lumps of steel roughly to shape from a bigger lump. Take care, angle-grinders can jump or snap blades, eye-protection essential. A Dremel is a sort of precision angle-grinder that can do reasonably delicate jobs.

Dave

Dave

Andrew Johnston24/08/2020 19:35:01
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Another illusion shattered; I though silver steel was a high carbon steel. crying 2

Andrew

Nigel Graham 224/08/2020 20:57:30
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I would not use grinding on a small machine-tool, because of the difficulty of keeping abrasive out of the bearing surfaces.

A slitting-saw is preferable, and the fly-cutter described by JasonB is a tried-&-trusted method for this sort of work.

Bazyle24/08/2020 20:58:37
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Quite often the blades of rotary mowers and such ike are fairly soft because the manufacturer is frightened of the consequences of a blade shattering if it hits a stone. My garden shredder blades seem to be mild steel again in case someone dropps a stone into it. I think garden sheers may be made of sterner stuff and before the era of tipped blades builder's circular saws were a good source.

SillyOldDuffer24/08/2020 21:27:20
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Posted by Andrew Johnston on 24/08/2020 19:35:01:

Another illusion shattered; I though silver steel was a high carbon steel. crying 2

Andrew

Only if you ignore the added Chromium, Manganese, Silicon, Phosphorous and Sulphur. DIN Silver Steel has a dash of Vanadium as well. It's an Alloy Steel.

Never mind shattering the illusion, I've shattered the real metal.

angel 2

Martin Kyte24/08/2020 22:16:26
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Silver Steel benifits from annealing before machining. A certain amount of cold drawing in manufacture means it is not at it's softest as delivered.

regards Martin

Andrew Johnston25/08/2020 08:46:25
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Posted by SillyOldDuffer on 24/08/2020 21:27:20:

...added Chromium, Manganese, Silicon, Phosphorous and Sulphur. DIN Silver Steel has a dash of Vanadium as well. It's an Alloy Steel.

So what unalloyed high carbon steel are you comparing it to?

Andrew

Baz25/08/2020 08:57:08
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Silver steel is a high carbon steel because it is high in carbon, regardless of what else is in it.

Michael Gilligan25/08/2020 09:08:55
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Andrew & Dave

I am minded of the Raven Paradox: **LINK**

https://en.wikipedia.org/wiki/Raven_paradox

... I will leave you with that thought, whilst I make breakfast angel

MichaelG.

roy entwistle25/08/2020 09:13:11
1459 forum posts

Sillyoldduffer Surely any steel is an alloy cheeky

David Noble25/08/2020 09:37:48
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Posted by Michael Gilligan on 25/08/2020 09:08:55:

Andrew & Dave

I am minded of the Raven Paradox: **LINK**

https://en.wikipedia.org/wiki/Raven_paradox

... I will leave you with that thought, whilst I make breakfast angel

MichaelG.

I hope that you're not having black tea with you breakfast Michael

David

Martin Kyte25/08/2020 10:04:57
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Well I would say that Silver Steel is a High Carbon Steel in the sense that it has enough carbon to make it hardenable. It is however not a PLAIN carbon steel due to the other elements added, so should properly be classed as a high carbon alloy steel. Calling something a high carbon steel does not preclude the inclusion of other elements to the mix but calling it plain carbon does.

regards Martin

Chris TickTock25/08/2020 10:16:18
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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

JasonB25/08/2020 10:33:58
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Posted by Chris TickTock on 25/08/2020 10:16:18:

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

Add to that Do Not use cloth to protect the machine as if it gets caught up bad things can happen. If you need to then news paper or a paper towel will be safer. I also have a piece of board I can lay over the lathe bed if using any abrasive, likewise some boards to lay on your mill table are a good idea for anywork as they prevent damages and help keep the tee slots clear.

SillyOldDuffer25/08/2020 10:49:59
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Posted by roy entwistle on 25/08/2020 09:13:11:

Sillyoldduffer Surely any steel is an alloy cheeky

True, but to be technically accurate Carbon Steels (0.05 to 2.5% C) are defined specifically as:

  1. no minimum content is specified or required for chromium, cobalt, molybdenum, nickel, niobium, titanium, tungsten, vanadium, zirconium, or any other element to be added to obtain a desired alloying effect;
  2. the specified minimum for copper does not exceed 0.40%;
  3. or the maximum content specified for any of the following elements does not exceed the percentages noted: manganese 1.65%; silicon 0.60%; copper 0.60%.

Alloy Steels are defined in the opposite sense as being any steel containing more than 1% of elements other than Carbon and Iron.

Silver steel breaks Rule 1. It's not a Carbon Steel.

The distinction is important because adding small quantities of elements other than Iron and Carbon radically alters the properties of the metal, governing how tough, malleable, strong, springy, hard or machinable it is. And how it responds to heat-treatment.

My point about Silver Steel aka Drill Rod remains: it's an alloy steel designed to simplify heat treatment in ordinary workshops. High-carbon steels behave similarly but need more care. They have to be cooled at just the right temperature and speed. Get it wrong, and the metal won't harden, or will over-harden and crack during the plunge, or warp. Small parts are extra tricky. Silver-steel is less fussy, making it worth spending a few bob on it rather than faff about hardening plain carbon steels.

Carbon steels are often used for cheapness, but they require more elaborate heat-treatment facilities than a blow-lamp and bean tin full of water! These days manufacturing seems to favour other alloy steels for making precision small parts like razor blades. Cheaper in a production environment to grind hard metal than to machine soft and then heat-harden.

Dave

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