Cutting tools – what type is most suitable?

[SillyOldDufferModerator @sillyoldduffer]

Posted by Andrew Johnston on 30/09/2019 14:40:04:

Posted by SillyOldDuffer on 30/09/2019 13:54:39:

 

I feel it's best not to confuse him unnecessarily with well meant advice about personal favourites.

Soooooo, we should be offering ill-considered advice based on things we know nothing about?

Andrew

Nah, it's only ill-considered advice I worry about. In this case the advice about HSS is fine, but I suggest it's not all well tuned to the needs of a completely new beginner who hasn't explained what he wants a lathe for yet.

I remember only too well the fear, uncertainty and doubt involved in starting off in this wonderful hobby. Last thing the beginner needs is to get bogged down in a partisan debate about Metric vs Imperial, British vs Chinese, HSS vs Carbide, Digital vs Analogue, Quality vs Affordable, Inverters vs Converters, Myford vs the Rest, Pencils vs CAD, or Manual vs CNC. (Valuable subjects though they all are in their place!)

Dave

 

Edited By SillyOldDuffer on 30/09/2019 15:51:18

[JasonBModerator @jasonb]

Posted by SillyOldDuffer on 30/09/2019 15:50:02:

. In this case the advice about HSS is fine, but I suggest it's not all well tuned to the needs of a completely new beginner who hasn't explained what he wants a lathe for yet.

I thought we knew the use from the first post

" My primary use of the lathe will be turning jewellery items from materials as soft as wax (investment casting) epoxy resins, aluminium for prototyping, brass, bronze and at some stage stainless steel. I will be both turning including putting bevels on and when I get a tailstock chuck in place boring up to 22mm on 25mm rod."

[JasonBModerator @jasonb]

For what it's worth I would go with a bit of both.

Sooner rather than later you will want "custom" shaped cutters that Inserts won't provide so you will need to grind your own so get a small 6" bench grinder and a few 6mm square HSS blanks and have a practice on those. Avoid the really cheap prices but ones from a known supplier will do, name brands are better but you do pay a lot more for them and probably won't notice a difference to start with.

I would also get a basic right hand insert holder which will both face the ends of your bar as well as turn along its length, one that takes the 80/100degree rhombic shape inserts is quite versatile as the same inserts can be used in other holders. Again avoid the really cheap and the commercial brands which are expensive. Something from one of the known hobby suppliers like Glanze, JB Cutting tools, ARC, etc will be fine. 6mm or 8mm shank if your toolpost will allow this will have a code SCLC-R and will take a nominal 6mm insert so have 06 after the letters.

Boring bars take a bit more effort to grind so I would also get one of those to take the same inserts. You don't say how deep you need to bore your holes but diameter suggests they will just be for rings so a large rigid bar is not needed. Something with an 8mm or 10mm dia shank which will be a couple of mm less in height will do and can be used to open up a 11-12mm drilled hole so no need for large diameter drills. These will have the code S08K-SCLC-R 06 or S10K-SClC-R 06 with the first part indicating the shank diameter and as before the same 06 size insert.

Holders more often than not come with a general purpose insert which for these holders will be CCMT 060404 but for your needs the inserts for cutting non ferrous metals will work better on both plastics, resins, wax and the metals you mention and a suitable insert will have the code CCGT 060404

[Will ColeParticipant @willcole59380]

Thanks for the additional info guys.

I measured the height difference from the bottom of the holder on the tool post to the tip of the centre which comes out at about 7.5mm. I am guessing that would best suit either 6mm or 8mm tool stock.

Looking at the boring tool I have, that would need an 18mm hole drilling and then it would be just over 1mm above the centre line, so probably not usable. As Jason rightly guesses, the primary reason for purchase is for jewellery rings. The maximum width of any piece is 12mm, with most being 6mm or 8mm depth of bore, so comparatively shallow, the internal diameter ranging from about 16mm to 21.5mm to suit finger sizes. I intend using a stepped mandrel to hold the rings away from the chuck to do final sand and polish using the lathe.

It is unlikely at this stage, that they lathe will be used for much other than working with jewellery rings, although I do realise things can become addictive..

[Howard LewisParticipant @howardlewis46836]

Whatever tools you use, they must be mounted so that the cutting edge is on the centreline of the lathe.

make yourself a centre height gauge, it will save a lot of messing about getting the tool to the correct height.

For the materials that you listed, I would think that HSS would suffice.

Learn how to grind HSS tools, the knowledge will always be useful. If you cannot find a book showing the clearance angle to which they should be ground; PM with your E mail address, and I'll look out my Apprentice notes and send you a copy.

But, +1 for the Diamond Turning tool. Easy to sharpen, only one face to grind, and works really well for turning or facing. A centre height gauge is invaluable for setting the toolbit correctly. may seem expensive to buy initially, but easy to use, and sharpen, and they last. Much cheaper than replacing tips, and more tolerant of impacts / intermittent cuts!.

If you intend to make 22mm holes, my advice would be centre or spot drill, pilot drill and then gradually open, in sensible steps. If the lathe is a mini lathe, a 400 or 450 watt motor won't take kindly to drilling 22mm diameter from scratch. To be safe, limit the cuts to 1 mm a side. Motors or control boards tend be expensive and inconvenient to replace. They always fail at the most inconvenient times, is there ever a convenient one?.

Howard

[old martParticipant @oldmart]

You are going to run into trouble straight away boring 22mm in 25mm stock, the finished wall thickness is only 1.5mm. 

It would be easier to get hold of tube and part it off while holding it in a collet.

Edited By old mart on 30/09/2019 21:44:28

[Will ColeParticipant @willcole59380]

I have looked at thick wall tube for the stainless only 'Old Mart', but I am not sure whether the welded seam on those would polish or machine out?

One of the problems with jewellery rings, is that the wall does need to be relatively thin for wearer comfort and weight considerations, as even substantial rings seldom exceed about 2mm wall thickness. Most ring sizes are under 21mm bore but I have to cover the full range of sizes so would probably have to move up to 30mm stock for larger ring sizes above if needed. This is one product where one size doesn't fit all sadly.

[John ReeseParticipant @johnreese12848]

I suspect at some time you will want to make some form tools. You will want HSS for that so get a grinder with proper wheels. Learn to grind your own tools. You will also want a Dremel or similar tool form inside radii on some tools.

[JasonBModerator @jasonb]

Posted by old mart on 30/09/2019 21:41:59:

You are going to run into trouble straight away boring 22mm in 25mm stock, the finished wall thickness is only 1.5mm.

Where is the problem? Hold a piece of bar with say 20mm sticking out the chuck, bore and then part off. No risk or distorting the ring with jaw pressure.

I managed a much deeper hole in some 38mm not long ago to leave 0.5mm wall

[IanTParticipant @iant]

Yes, I recently needed an adaptor ring for a 5/8" Freud saw blade to match my 1/2" saw arbor – so drilled & bored some mild steel stock to 1/2" and then turned it down to 5/8" – in that order.

It was then very easy to part off 1mm slices (the blade thickness) and with the parting 'flash' removed the 1/16" x 1mm ring worked perfectly… and I also now have five spares for when I lose the first one.

Mention this because I've always bored to size and then turned down the outside diameter (in that order). Not sure if this is really essential thinking about it but it has always seemed the better way to do it…

Must try for a 0.5mm ring – just for fun.

IanT

P.S. Will Cole – my only advice would be that if you do decide to use HSS tooling (which I'd recommend) – then buy 1/8" or 3/16" (my own preference) HSS blanks rather than anything larger. Smaller HSS tools are much easier & quicker to both initially shape and then to keep sharp.

[SillyOldDufferModerator @sillyoldduffer]

In defence of sets, I came across this nice graphic on Warco's Website showing types of cut taken by various holders and inserts.

Anybody not doing all of them?

Dave

[Anonymous]

Posted by SillyOldDuffer on 01/10/2019 12:20:10:

Anybody not doing all of them?

Me! I don't do all of them.

But on the other hand I do several that are not shown.

Andrew

[Will ColeParticipant @willcole59380]

Okay, have managed to get a photo of something similar to what I am planning to create.

This is actually a two piece titanium ring base with screw thread to connect the one side flange but gives a visual representation of the sort of thing.

At this point, I stress the point I am not looking to work with titanium nor create screw threads, but to create this as a one piece item in stainless. On some designs there would be two inset channels rather than one, but hopefully you guys will see what I need to machine.

[Mick B1Participant @mickb1]

Posted by Andrew Johnston on 01/10/2019 12:42:46:

Posted by SillyOldDuffer on 01/10/2019 12:20:10:

Anybody not doing all of them?

Me! I don't do all of them.

But on the other hand I do several that are not shown.

Andrew

Same here as you say. And I don't need a separate tool to do each of them. And I've still got 22 different HSS tool profiles to hand, even if some of them have only been used once or twice.

[JasonBModerator @jasonb]

Will for something like that you would also need a parting tool I suggest insert type or combined parting/grooving to cut the central recess which I assume is filled with resin or other metals. The advantage of the combined tool is that you can also get half round ended inserts which leave a nice internal fillet

The convex outer edges could simply be shaped with a file held against the work as it rotates after a few roughing cuts to remove the excess. You could also grind up an HSS tool with a concave cutting edge that would do the job and may be better if you have a number of similar rings to make.

I would tend to do most of teh external shaping while still on the end of a solid bar, then drill and bore to size before parting off (use same parting tool as above) Then mount on your mandrel for final finishing and polishing.

[JasonBModerator @jasonb]

Don't think I would touch Dave's set those parting and threading inserts are not common, seem to remember a couple of posts where posters were trying to get them.

[Will ColeParticipant @willcole59380]

Thanks Jason. The angles at the top edge of the ring going from the inset outwards are just regular bevels, it is the reflections off the material that makes them look rounded. There is also a tiny bevel on the edge of the inner surface of the ring to prevent the ring edge digging into the finger.

At the moment my thought is to buy a small set of insert tools, preferably with a boring tool and insert, but also get some HSS blanks to create my own tooling as well. Whilst many of you guys have perhaps decades of experience and can create tools for any job imaginable, for those of us new to lathe turning, it is a little more challenging. With my CNC mills, I buy stock cutting bits and if they get broken just buy some more, but I appreciate that lathes are a whole different ball game and it is possible to create some really bespoke tools.

I do take on board all of the comments that people have made and have gained a lot of insight from this thread. You guys are incredibly helpful and I appreciate the time that all of you take to help newbies like myself.

[Will ColeParticipant @willcole59380]

*** UPDATE *** Thanks for all you guys for your input into this thread, which has helped me a lot.

I bought some decent quality hss tool blanks as suggested and found it much easier to grind them 'freehand' than expected. I did however buy a pre-ground hss boring tool, as the geometry on that is far more challenging for a newbie.

Having an outstanding birthday present from my wife, I decided to switch from a potential replacement wheelbarrow, to a set of inexpensive TCMT indexed cutting tools. Surprisingly these are actually very good quality and work well for my intended use.

Do I prefer one set of cutting technology over another? Well I am still at the stage where both of them create the shapes I require in a much quicker timescale than I had anticipated, so am happy with both.

You guys on this forum are great and it is a pleasant change to find folks that actually give practical helpful advice, rather than making pointless sarcastic comments.

[Howard LewisParticipant @howardlewis46836]

One advantage of HSS is that if you chip the edge late on Saturday evening, the tool can be reground and back cutting again, in minutes. Sod's law says that if the same thing happens at the same time with a replaceable tip, the last spare is the one that has just failed, so work has to stop, at least until Monday!

Most of the time, for turning, I use a Tangential tool with a HSS toolbit, but if the material is hard, Carbide will cut it. (Lovely red hot wire, or pretty blue chips, coming off! ) I use carbide for roughing, a lot of the time, and always for boring.

Carbide does not seem to like me banging it into the work, HSS is a bit more tolerant!

Howard

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