Grinding your own lathe cutters

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 18/08/2019 16:42:14:

… I think you mentioned a 20mm long staff for a platform escapement

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For general info. **LINK**

http://www.learnclockrepair.com/balance-staff-critical-dimensions-variants/

… and no, I've never managed to make a useable one yet !

MichaelG

[JasonBModerator @jasonb]

Thank's for that Michael. I was thinking of asking whet the part looked like.

Are the "trumpet" shaped ends critical or would a taper do? As I said in the thread about radius tools a graver would more than likely have been used and for those trumpet shapes and the undercut it would be the best tool for the job as I can't see it being done with off the shelf brazed tooling or inserts for that matter though you may get close with a RCGT one.

[Michael GilliganParticipant @michaelgilligan61133]

Trumpet shape is not critical, Jason … it's just a smooth blend, for appearance and to avoid stress-raisers.

I don't know anyone who has done these without using a graver : But obviously it must be possible with the right machines, because the modern factories churn them out.

These days they are probably available as truly interchangeable parts, but they were typically supplied to the repair trade in 'machined but not finished' form.

MichaelG.

[Chris TickTockParticipant @christicktock]

Posted by Michael Gilligan on 18/08/2019 17:49:52:

Posted by Michael Gilligan on 18/08/2019 16:42:14:

… I think you mentioned a 20mm long staff for a platform escapement

.

For general info. **LINK**

http://www.learnclockrepair.com/balance-staff-critical-dimensions-variants/

… and no, I've never managed to make a useable one yet !

MichaelG

Hi Michael, thanks I already have that link in my notes.

[Chris TickTockParticipant @christicktock]

Obviously many members on this forum have far greater expertise than I currently do in terms of machining. But and it is a big but I see no one yet who is an expert in making a balance staff. That is obvious and to be largely expected and on that basis all I really seek from the forum is help with general lathe technique and tooling.

As some of you are aware I do have the help from a very well known horologist / craftsman who has been making clocks including balance staffs for many years that I rely on for this specific advice.

Whilst I trust the advice given to me detailing specific cutters and general technique from my friend is accurate and genuine there are obvious hurdles in skill level to overcome that he may for good reason leave out at my early stage.

Therefore all further posts will be directed to more general points of lathe skill where a great deal of work must be undertaken in order to progress..

A big than you for the help thus far.

Chris

[Douglas JohnstonParticipant @douglasjohnston98463]

I'm glad to see that polished carbide inserts as sold for aluminium are making more fans amongst hobbyists. I have been using and advocating these inserts for some years but there always seemed to be a distinct prejudice against any carbide for hobby size lathes.

I was lucky enough to buy a whole bunch of these inserts very cheaply on ebay a number of years ago and have become more and more of a fan ever since. The ones I got were top quality branded ones but I notice that you can buy this type of insert very cheaply from China. I don't know if the Chinese ones are any good but they must be worth a punt.

It is the sharp edge and high positive rake that makes all the difference on a small lathe. You can feel them slicing through metal with very little effort and I have found they work very well on all types of metal including hard steel and cast iron. They are also an absolute delight for boring.

Doug

[Martin Hamilton 1Participant @martinhamilton1]

Doug i have been using the cheap aluminium inserts from China for a while now on small lathes, i find they are a delight to use on most materials. They make such a clean crisp accurate cut with very little tool pressure on the work piece needed, which is what small low powered lathes need.

[Douglas JohnstonParticipant @douglasjohnston98463]

Martin- nice to know that the Chinese ones are worthwhile. If my stock ever runs out I know where to find more without breaking the bank.

Doug

[John HaineParticipant @johnhaine32865]

Christopher, given the you have a small lathe you may find this thread interesting.

**LINK**

also somewhere I described using it on a flat base like the "Turnado " for hand turning.

[JimDParticipant @jimd42132]

Posted by Martin Hamilton 1 on 18/08/2019 21:48:48:

Doug i have been using the cheap aluminium inserts from China for a while now on small lathes, i find they are a delight to use on most materials. They make such a clean crisp accurate cut with very little tool pressure on the work piece needed, which is what small low powered lathes need.

Morning Martin, do you have a link to the Chinese Aluminium inserts? Pm me if its classed as advertising here.

Thanks!

Edited By JimD on 19/08/2019 08:44:01

[John HaineParticipant @johnhaine32865]

Found it!

**LINK**

[Chris TickTockParticipant @christicktock]

Posted by JasonB on 17/08/2019 13:47:04:

Posted by Christopher judd on 17/08/2019 13:40:31:

brazed carbide will be better as it will be made more exactly than home ground HSS.

Chris

When you buy brazed carbide tools they come roughly shaped and will at a minimum need to be touche dup with a diamond stone, in teh long tem they will need freshening up with a bench grinder and that will need either a green grit or diamond wheel, the supplied wheels won't sharpen carbide.

So the brazed ones will be no more exact than HSS and as they are harder to shape and sharpen probably less exact

You then get into the quality of the bit of carbide that is brazed to the holder, plenty of cheap ones about for 50p but the carbide is not the same as ones for £20.

Edited By JasonB on 17/08/2019 13:50:22

Hi Jason , I am looking again into inserts and brazed carbon cutters. I chipped the first one I used almost immediately. OK I'm a beginner so half expected. But now looking at the other brazed carbide (all Sherline made) it has its cutting edge without any chamfer or landing. This makes it fragile I believe. So is the buyer of such cutters supposed to introduce a chamfered / honed edge on these cutters. As the Sherline is such a small lathe it would increase the power needed to make cuts with a honed cutter. Your thoughts?

Chris

[JasonBModerator @jasonb]

Quite the opposite brazed carbide is less prone to damage as the edge is not so fine and is better supported.

As I said earlier you will need to grind and hone brazed cutters as they seldom cone ready to use certainly for fine work despite what your Guru says. I gave details of what you need to grind and hone them with.

[Chris TickTockParticipant @christicktock]

Posted by JasonB on 27/08/2019 12:52:48:

Quite the opposite brazed carbide is less prone to damage as the edge is not so fine and is better supported.

As I said earlier you will need to grind and hone brazed cutters as they seldom cone ready to use certainly for fine work despite what your Guru says. I gave details of what you need to grind and hone them with.

thanks Jason, yes I have all the notes to sharpen brazed carbide. I have looked on the Sherline site where they sell these no mention of fettling with them in terms of either honing or sharpening before use. The cutting edge removes a scraping from my finger nail so they are sharp. But is honing the edges necessary?

chris

[JasonBModerator @jasonb]

Just as with HSS a honed edge to the tool will give a sharper edge and therefore better finish than straight off the grinder so either an oilstone for the HSS and or Diamond lap or scary sharp for both types of tool will give a better finish for fine work

It also prolongs the life of the tool, if you just grind it each time it looses its edge you will wear it quickly, a touch up on a stone will not take much off but restore the edge.

[Chris TickTockParticipant @christicktock]

Posted by JasonB on 27/08/2019 13:46:04:

Just as with HSS a honed edge to the tool will give a sharper edge and therefore better finish than straight off the grinder so either an oilstone for the HSS and or Diamond lap or scary sharp for both types of tool will give a better finish for fine work

It also prolongs the life of the tool, if you just grind it each time it looses its edge you will wear it quickly, a touch up on a stone will not take much off but restore the edge.

Jason as the greenhorn here I expect I am misunderstanding something. But honing as I have seen it defined is creating a certain radius between two cutting edges and to improve the surface finish and use of the tool. Putting a curve in place of the sharp edge makes the tool more robust, helps prevent dig in but is not in itself sharpening the tool. Thus if I was to hone the Sherline tool as sent me I would be in effect blunting it???? So what is thev purpose of the stone to sharpen, to sharpen then hone or?

Regards

Chris

[ChrisBParticipant @chrisb35596]

The radius you create is at the tip not the cutting edges. When you hone you create a rounded nose on the tip and sharpen the edges.

Look at this video, it's explaining the process in detail:

[Chris TickTockParticipant @christicktock]

Posted by ChrisB on 27/08/2019 15:05:20:

The radius you create is at the tip not the cutting edges. When you hone you create a rounded nose on the tip and sharpen the edges.

Look at this video, it's explaining the process in detail:

Great video thanks Chris

[Chris TickTockParticipant @christicktock]

What I have been trying to get across is that there is a difference between sharpening and honing. In the LINK Chris B posted the man sharpens and hones the tool (nose radius). Now my former question in relation to brazed carbide inserts is valid at leasr I think so. Some brazed carbide sellers offer tools honed in other words there edges are tailored for additional tool life and different rake angles. My question in relation to the Sherline brazed carbides which came without apparent honing but sharp was is the user normally expected to hone these tools upon receipt. As always common usage probably means the words sharpening and honing may just be used when either may well apply.

Chris

[JasonBModerator @jasonb]

You don't have to hone just the tip, you can hone the two flat vertical edges and the flat top, A cutting edge is where two flat planes meet the finer you get that meeting point the sharper the cutting edge. You are better off using the terms grinding and honing, grinding will give the basic shape, honing will refine the cutting edge.

Please post a link to these pre honed brazed tools.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Chris TickTock on 27/08/2019 15:34:38:

What I have been trying to get across is that there is a difference between sharpening and honing.

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I think what you need to appreciate, Chris, is that 'honing' is a process [which typically involves removing much smaller quantities of material than 'grinding'] … It is not, of itself specific to the production of any particular shape.

MichaelG.

[not done it yetParticipant @notdoneityet]

Even HSS cutters benefit for honing. In fact, any cutting edge benefits from honing. However, there is little point in honing a rough edge, unless it is soft enough to be adjusted by the honing process.

Very wide cutters, for wood planers, were always sent out for re-grinding. However, they were always honed regularly, to retain a keen cutting edge until they needed to be sent back for re-sharpening. The re-sharpening process ensured an even cut across the 300mm, or more, of the planer – but the honing kept that cutting edge sharp for as long as possible.

If you were old enough you might remember the barber honing his cut-throat razor on a leather strop, before commencing a shave.

Just remember, the cutting edge production process might comprise both coarse and fine grit abrasive wheels for starters – neither of which will provide the optimum cutting edge – or not for long. Honing is simply an extension of improving the basic tool geometry.

Just like converting rough machined surfaces to a mirror finish – no point in missing out on the intermediate abrasives – or one would simply be polishing the rough edges, not removing the coarser finish.

[Nick Clarke 3Participant @nickclarke3]

Posted by ChrisB on 27/08/2019 15:05:20:

The radius you create is at the tip not the cutting edges. When you hone you create a rounded nose on the tip and sharpen the edges.

Look at this video, it's explaining the process in detail:

Thank you for the video link – really learnt a lot.

Nick

[Paul LousickParticipant @paullousick59116]

I recently found this article in a 1956 edition of Popular Mechanics magazine for a basic tool cutter grinding holder, used for sharpening tools on the lathe and written by Rodney B Wyatt.

Neil, any relation ?

Paul

[IanTParticipant @iant]

Just to add a few thoughts on "honing" (entirely my own views).

A good deal of time I don't hone my HSS/Carbon tooling because I'm working larger pieces or don't need any special finish. I'll just touch up a HSS tool on the grinder but it's useful to be able to use roughly repeatable settings, so some aid/guide in grinding is essential and for some tools I'll make a scratch mark to show where the tool 'sat' in the jig/fixture previously (when using the Diamond jig for instance).

Where honing is important is when you need a very sharp tool – for very small work, a very fine cut or awkward work needing a tool extension (a sharp tool helps reduce chatter). For some time now I've tried to always use the front of the wheel on my 6" grinder and this will give a small curve to the grind. This can be exaggerated by slightly lifting the tool above the grinders centre height. This curve does two things, it gives a small clearance but also creates two edges (top & bottom) that can be honed much easier than a flat surface.

I always hone with the tool out of the tool holder and although I do sometimes use a small stone to 'touch-up' the tool in-situ, I don't really think of this as "honing".

It's a very simple thing to do once you get the general idea and does give a very sharp edge. A tool can also be re-honed several times but (in my view) the tool must be removed from the holder to do this properly. I've dug out a photo I thought I'd posted before (but it wasn't in my Albums – so maybe not). It's a shaper tool I probably honed for cast iron but you can clearly see the (bright) honed cutting edge (the bottom edge just helps to level the tool when honing). The 'dull' face between the bright parts has in fact been ground and you can see the grinding marks in this face – the honing smooths this and gives a very good edge. This approach works for just about any cutting tool.

For context, I work on mainly on smaller stuff and others may have very different needs and experiences. I do use insert tooling but not for my general work. Maybe it's a matter of personal preference – a bit like Marmite.

Regards, IanT

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