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Grinding your own lathe cutters

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David Standing 117/08/2019 10:47:44
1266 forum posts
45 photos

Posted by Christopher judd on 17/08/2019 10:22:38:

My policy is never borrow a book as it lead to falling out if it gets forgotten, but your a mate for offerring.

Chris

Same here. Have had a few fallings out over exactly that in the past (books that were borrowed from me, in one case the borrower having subsequently 'lost' it).

Barrie Lever17/08/2019 10:48:24
323 forum posts
1 photos

Chris

If you want to borrow the book then send me via PM your address details.

Take a look at the reviews of the book on Amazon.

https://www.amazon.com/Tabletop-Machining-Joe-Martin/dp/0966543300#customerReviews

The book really is a bible for Sherline owners.

You will not fall out with me over a book.

Best Regards

Barrie

David Standing 117/08/2019 11:23:12
1266 forum posts
45 photos

Barrie

And obviously my borrowing/lending books comment was not pointed at you, Christopher, or anyone else on here smiley

Chris TickTock17/08/2019 11:47:06
163 forum posts
1 photos
Posted by David Standing 1 on 17/08/2019 11:23:12:

Barrie

And obviously my borrowing/lending books comment was not pointed at you, Christopher, or anyone else on here smiley

Thanks Barry my man is sorting out a copy of said book, I already have another 'the home Machinists book' so with the 2 should have a fair source of information.

Chris TickTock17/08/2019 11:50:31
163 forum posts
1 photos

Going back to inserts as I have been doing some research. I have found that the inserts that you rotate usually have a negative rake and this makes them unsuitable for a tiny Sherline. However as I am still grappling with the available issues could anyone state that there are decent positive rake carbon inserts suitable for the Sherline.

Regards

Chris

Vic17/08/2019 12:25:25
2204 forum posts
10 photos

It may be a generalisation too far but I’ve found the polished inserts work very well and suspect they would be good for small lathes like the Sherline, in a suitable size.

Something like this?

**LINK**

Maybe even the next size up.

Michael Gilligan17/08/2019 13:12:02
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13781 forum posts
599 photos
Posted by Christopher judd on 17/08/2019 10:29:47:

OK guys I have come across the CarbideDepot's insert table [ ... ]

(1) Looking under the Shape table is a Greek Symbol...anyone care to explain

.

If you mean this table, Chris: **LINK**

http://www.carbidedepot.com/formulas-insert-d.htm#shape

... I see no Greek : Just a misrepresentation of the degree symbol

[ it's a problem with the choice of font ]

MichaelG. [using an iPad]

.

and if that's not what you mean, just ignore me

Chris TickTock17/08/2019 13:34:27
163 forum posts
1 photos
Posted by Michael Gilligan on 17/08/2019 13:12:02:
Posted by Christopher judd on 17/08/2019 10:29:47:

OK guys I have come across the CarbideDepot's insert table [ ... ]

(1) Looking under the Shape table is a Greek Symbol...anyone care to explain

.

If you mean this table, Chris: **LINK**

http://www.carbidedepot.com/formulas-insert-d.htm#shape

... I see no Greek : Just a misrepresentation of the degree symbol

[ it's a problem with the choice of font ]

MichaelG. [using an iPad]

.

and if that's not what you mean, just ignore me

Thanks Michael that solves that one..well done.

Chris

Chris TickTock17/08/2019 13:40:31
163 forum posts
1 photos
Posted by Vic on 17/08/2019 12:25:25:

It may be a generalisation too far but I’ve found the polished inserts work very well and suspect they would be good for small lathes like the Sherline, in a suitable size.

Something like this?

**LINK**

Maybe even the next size up.

Hi Vic, look I am a green horn so I buzz around here and there forming opinions but my thinking based on my findings is that my Sherline works best with HSS but for tiny precise stuff quality brazed carbide will be better as it will be made more exactly than home ground HSS. Having said that the sharpness and rake of the Aluminium inserts has been offered up and seems credible for me at some point to explore. So thanks for your contribution it is noted.

Chris

JasonB17/08/2019 13:43:42
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15988 forum posts
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Do be careful looking at carbide depot and some other US sites as they use ANSI & ISO codes where just about all the information you are being given here is for ISO codes.

Yes There are decent inserts for the Sherline available, sherline even sell them but not worth buying from them as postage will be high.

Not sure what you mean by "rotate" but the CCMT, CCGT, DCGT etc that have been suggested can all be turned around in the holder to use the opposite corner and in the case of CC** inserts with an additional holder the other two 100deg corners can be used too.

Steve Crow17/08/2019 13:44:41
147 forum posts
32 photos

Posted by Vic on 17/08/2019 12:25:25:

It may be a generalisation too far but I’ve found the polished inserts work very well and suspect they would be good for small lathes like the Sherline, in a suitable size.

Something like this?

**LINK**

Maybe even the next size up.

I've been using those very same inserts all morning to turn tapers on 3mm silver steel on a Sherline. Run it at full speed - great finish.

JasonB17/08/2019 13:47:04
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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

Chris TickTock17/08/2019 14:01:15
163 forum posts
1 photos

I would be a fool to dismiss anyone's opinion yet on this matter. I suspect the truth is for most instances using the aluminium inserts will do just fine and yes I will be trying these. On the other hand One of the very top craftsman who can machine every part of a clock including the platform escapement only uses hss and quality brazed carbon for very small and fine work. I suspect the degree of accuracy is greater for the really small stuff. On the other hand you guys stating the inserts do a fine job may be right and my other forum friend hasn't had success with them. As always opinions and opinions, everyone welcome.

Regards

Chris

Chris TickTock17/08/2019 14:05:59
163 forum posts
1 photos
Posted by JasonB on 17/08/2019 13:43:42:

Do be careful looking at carbide depot and some other US sites as they use ANSI & ISO codes where just about all the information you are being given here is for ISO codes.

Yes There are decent inserts for the Sherline available, sherline even sell them but not worth buying from them as postage will be high.

Not sure what you mean by "rotate" but the CCMT, CCGT, DCGT etc that have been suggested can all be turned around in the holder to use the opposite corner and in the case of CC** inserts with an additional holder the other two 100deg corners can be used too.

Thanks Jason I will watch out for the ISO / Ansi issue.

Martin Hamilton 117/08/2019 16:23:29
130 forum posts

In my opinion & experience on my Sherline the **gt inserts are superior re finish & tool pressure on the workpiece for small lathes. I still use some HSS tools where i need a more dedicated tool to what i can use in inserts, there are more now starting to use aluminium inserts on very small lathes as they find out just how good the are on most types of metals & plastics etc on smaller machines. Using **mt inserts on these small lathes will not give as nice finish generally but i do also use them as well.

Chris TickTock17/08/2019 16:36:56
163 forum posts
1 photos
Posted by Martin Hamilton 1 on 17/08/2019 16:23:29:

In my opinion & experience on my Sherline the **gt inserts are superior re finish & tool pressure on the workpiece for small lathes. I still use some HSS tools where i need a more dedicated tool to what i can use in inserts, there are more now starting to use aluminium inserts on very small lathes as they find out just how good the are on most types of metals & plastics etc on smaller machines. Using **mt inserts on these small lathes will not give as nice finish generally but i do also use them as well.

Thanks Martin, there definetly is a body of opinion supporting their use.

Chris

Chris TickTock18/08/2019 09:33:10
163 forum posts
1 photos

To do posters here justice over their views on using aluminium inserts on a small lathe I went back to my horological friend for a second opinion. He stated in his opinion inserts can be used without issue for larger work but on micro work often undertaken in the horological field inserts are not appropriate. Regarding quality brazed carbon cutters as they have been recommended they can be used as they come needing no setting up. The person giving this advice is a world renowned craftsman so you can see why at this stage in my lathe experience I will be sticking with it as all my work will also be horological. Suffice to say though I will at some point try aluminium to gauge the results.

Regards

Chris

Michael Gilligan18/08/2019 09:50:12
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13781 forum posts
599 photos
Posted by Christopher judd on 18/08/2019 09:33:10:

[ ... ] I went back to my horological friend for a second opinion. He stated in his opinion inserts can be used without issue for larger work but on micro work often undertaken in the horological field inserts are not appropriate. Regarding quality brazed carbon cutters as they have been recommended they can be used as they come needing no setting up. The person giving this advice is a world renowned craftsman so you can see why at this stage in my lathe experience I will be sticking with it as all my work will also be horological. [ .... ]

.

Forgive me please, if this an impertinent question

Has your 'world renowned craftsman' friend discussed the use of the graver ?

For work such as turning balance-wheel staffs [which is, I think, your stated ambition], this would normally be the preferred tool.

MichaelG.

.

P.S. have you looked at the Saunier book that I linked on your 'digital calipers' thread ?

[quote]

This is a very good place to start: **LINK**

https://archive.org/details/watchmakershand00tripgoog/page/n4

[/quote]

SillyOldDuffer18/08/2019 10:41:27
4587 forum posts
980 photos
Posted by Christopher judd on 18/08/2019 09:33:10:

...

The person giving this advice is a world renowned craftsman so you can see why at this stage in my lathe experience I will be sticking with it as all my work will also be horological. Suffice to say though I will at some point try aluminium to gauge the results.

Regards

Chris

I think you may be missing the point slightly: what a world renowned craftsman does may not be the best place for a beginner to start! Learner drivers shouldn't begin by asking Lewis Hamilton which oil is best for Formula 1.

Correctly sharpened HSS is very suitable for small lathes and - as lathes go - the Sherline is tiny. So the obvious answer is use HSS, and why not? The main objection is a beginner might find he doesn't have the skills or equipment needed to correctly sharpen HSS. The equipment is easy enough - a grinding wheel - but learning to use it may not be.

As is often the case, the operator is more important than the equipment. If Christopher Judd happens to be a grinding natural, and some people are, then all is well with HSS. But if he's cack-handed like me, then frustration ensues. In that case carbide inserts remove the need for the operator to develop grinding skills. Eliminating causes is useful at the early stages when it's not clear if the lathe, material, cutter-type, set-up, speed, depth of cut or feed-rate are wrong.

In practice I use both carbide and HSS. It's allowed! Mostly carbide because it's convenient - there's no point me wasting time sharpening HSS when carbide will do the job. When carbide fails, mostly by not getting a good finish or something very delicate is in hand, out comes HSS and a short fight with my grinder. It's possible to buy HSS inserts to fit carbide holders, but I'm not that clumsy. A good alternative to HSS for fine hobby use is the carbide inserts used by the grown-ups on non-ferrous metals like Aluminium. Like HSS they're sharp and polished, simple as that.

Part of the fun is developing the skills needed to get the best out of tools and materials. What suits other people doing other types of work on different equipment can be highly misleading. The best way to find out is to grind some HSS tools and cut metal: if the advice works for you, hurrah. If results are poor, try carbide.

You also said 'Regarding quality brazed carbon cutters as they have been recommended they can be used as they come needing no setting up.' That's a booby trap because brazed carbide tools often come unsharpened. The advantage of brazed carbide over inserts is they're cheap and can be ground to shape like HSS and resharpened. A special grinding wheel is needed. I never use them.

Dave

JasonB18/08/2019 10:45:51
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15988 forum posts
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Looks like you have already decided but going back to somebody else's comment that carbide inserts can't take small cuts which seems to be putting you off here is an insert designed for aluminium taking a 0.001" cut of some EN8 steel. Not ideally focused but if you watch it full screen on youtube you can see the nice ribbon of swarf coming off.

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