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Grinding your own lathe cutters

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Steve Crow18/08/2019 11:52:19
149 forum posts
32 photos

Chris, with respect to your mentor, I strongly advise that you take the advice of the forum members.

I did and I don't regret it.

I had a similar problem regarding the Sherline. See my thread "A Kitchen Table Workshop - Grinding Problems" (I don't know how to link it). I took the forums advice and bought a holder and inserts and some HSS Co5 6mm tools.

Centre them properly and you'll be getting excellent results straight away. They are fine with silver steel down to sub-millimeter diameters. I've cut a M1 thread with the HSS and turned a 0.5 diameter with the inserts all in silver steel with a good finish.

Take my word, try these and you can be cutting metal as soon as possible. There is no substitute for getting stuck in and making some swarf.

Steve

Old School18/08/2019 12:21:03
239 forum posts
7 photos

I was also helped along my way to "model engineering" by a clockmaker he taught me to grind lathe tools in hss and make form tools from carbon steel for making pillars and fly cutters for wheel cutting. This person was my father who made his living from making clocks from simple skeleton clocks with escapements you only saw in books to orrery clocks all to his own design and made from scratch.

JasonB18/08/2019 13:26:21
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Chris, you also mentioned a need for precision, you don't say what accuracy you are chasing but having now finished the part in the video I posted earlier I thought I had better measure it.

I was aiming for 10mm, on crankshafts I do tend to use my micrometer so dug out the analogue one as I find the feel better than my digital one, as this is imperial I need to get 0.3937", the mic has a 10ths scale that is each line represents 0.0001" or 0.0025mm. I'm happy with the size I managed to hit, you may feel you need more precision.

Even the hand fed cut on the taper came out nicely straight off the tool.

Michael Gilligan18/08/2019 13:58:12
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13800 forum posts
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Posted by Steve Crow on 18/08/2019 11:52:19:

[ ... ]

I had a similar problem regarding the Sherline. See my thread "A Kitchen Table Workshop - Grinding Problems" (I don't know how to link it). I took the forums advice and bought a holder and inserts and some HSS Co5 6mm tools.

[ ... ]

.

Allow me, Steve: **LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=142594

... It's a thread well-worth a look.

MichaelG.

Chris TickTock18/08/2019 15:18:43
163 forum posts
1 photos
Posted by Michael Gilligan on 18/08/2019 09:50:12:
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]

Thanks Michael the answer is yes we have discussed gravers and that the advise was years of practice are need to turn a staff on a graver and to not go that way as a beginner.

Chris

Chris TickTock18/08/2019 15:26:57
163 forum posts
1 photos

Hi guys thank you for all your posts they have not been in vain because as I said I will use aluminium inserts at some point and assess the difference. At the moment I ask a lot of questions and take a view that in all likelihood may change with experience.

To an extent tools used are like one's politics deeply believed right but at the end of the day we are all but bigots.

Regards

Chris

SillyOldDuffer18/08/2019 16:08:05
4592 forum posts
980 photos
Posted by Christopher judd on 18/08/2019 15:26:57:

...

To an extent tools used are like one's politics deeply believed right but at the end of the day we are all but bigots.

Regards

Chris

I hope not Chris! Evidence based choices are the foundation of engineering, not personal opinion.

As advice often depends on context don't be afraid to test ideas and reject them but never reject advice simply because it doesn't happen to align with what you believe. People are often wrong, especially me!

It takes time and experience to filter good from bad - the important thing with machining is to try it and see. Actually using HSS and Carbide for a few weeks will make the issues much clearer.

Dave

Michael Gilligan18/08/2019 16:42:14
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13800 forum posts
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Posted by Christopher judd on 18/08/2019 15:18:43:

.

Thanks Michael the answer is yes we have discussed gravers and that the advise was years of practice are need to turn a staff on a graver and to not go that way as a beginner.

Chris

.

I will, genuinely, be very interested to know how you get-on; turning a staff with any tool that is not making a shearing cut.

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

MichaelG.

ChrisB18/08/2019 17:03:15
394 forum posts
162 photos

I started off with HSS, could not get proper results with it and rather than turning I spent more time grinding - which was frustrating. So I quickly turned to carbide inserts. Most probable reason for my bad experience with HSS is that the material I use for turning is of ''unknown'' origin, ( read recycled bolts etc) so I could be turning HT steel, stainless etc without any idea of what the speeds and feeds should be.

Using carbide changed all that, I mostly use tnmg inserts which I see as economical (having 6 useable tips). My time at the workshop immediately became more enjoyable and less frustrating. I also got some used cbn inserts (same shape) which give mirror finish at high revs even with shallow cuts (it's more burnishing than cutting I think)

I had read forums (on here as well) telling beginners to only use hss and learn how to grind tools, and to read books etc. To some extent I agree with that, but I think that sometimes it's better to do what you feel comfortable with and learn as you go, rather than getting bored and then loose interest.

My 2cents worth as a beginner.

Michael Gilligan18/08/2019 17:49:52
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Posted by Michael Gilligan on 18/08/2019 16:42:14:

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

.

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

JasonB18/08/2019 18:26:22
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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 Gilligan18/08/2019 18:36:59
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13800 forum posts
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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 TickTock18/08/2019 19:07:59
163 forum posts
1 photos
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 surprise

.

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 TickTock18/08/2019 19:43:32
163 forum posts
1 photos

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 Johnston18/08/2019 20:14:12
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599 forum posts
32 photos

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 118/08/2019 21:48:48
130 forum posts

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 Johnston18/08/2019 22:57:48
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599 forum posts
32 photos

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 Haine19/08/2019 08:04:24
2591 forum posts
133 photos

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.

JimD19/08/2019 08:43:36
13 forum posts
3 photos
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 Haine19/08/2019 08:55:17
2591 forum posts
133 photos

Found it!

**LINK**

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