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Grinding hss

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Chris Farbrace	20/10/2009 22:44:04
17 forum posts	Hello,there have been several accounts of poor finish etc using carbide tipped lathe tools and I have to admit my disappointment with the results on my Asian lathe also.As a complete beginner I was undecided whether to go for indexed carbide or hss and obviously wrongly opted for a couple of glanze indexed tools,it seems no matter what i try the finish on fcms is rough and the tips seem to damage very easily.The lathe has been stripped and rebuilt after thouroughly cleaning and greasing and the carriage and slides gibs adjusted to eliminate any play but carbide does not seem to work for me, now to try hss.Can anyone advise on the right bench grinder to purchase,almost all seem to have one 30g and one 60g wheel,various power ratings and either 150mm or 200 mm dia wheels and ranging from cheapo to ultra pricey(like Metabo).Is there(peferably) a website with good instruction for grinding lathe tools suitable for a beginner?Any help you experienced guys could provide would be gratefully recieved,many thanks regards Chris Farbrace
LADmachining	20/10/2009 23:10:05
126 forum posts 11 photos	Hi Chris, I use the Glanze indexable tools almost exclusively, as they have always worked well for me, give a good finish and the tips last a fair while. Do you have SCLCR tools, with the rhombus shaped tips? Are you using any coolant whilst turning? What size is the lathe you are using? I first used the Glanze tools on a Chester Conquest lathe. Whilst the finish was better than using HSS, it was only just acceptable. Different grades of steel, even supposedly free cutting types, didn't improve matters much. Only leaded mild steel gave an improved finish. With my newer, much larger lathe (Warco BH600), the finish on most steels is very good with the Glanze tools. Aluminium, turned with a spray of WD-40, comes out with a very fine finish. Have you tried turning any aluminium on your lathe to see if it is just your steel causing you the finish problems? For the few tools I do use in HSS (radius or thin grooving tools), I have a Machine Mart 6inch grinder with supplied coarse and fine wheels - still going strong after 6 years of average use. There are many books with info about grinding lathe tools - look at 'The Amateurs Lathe' by Sparey (which contains a lot of other useful info). Another is 'Model Engineering - A Foundation Course' by Wright. A web search for 'lathe tool grinding' will list a number of sites that should give you some hints... Regards, Anthony
chris stephens	21/10/2009 01:01:06
1049 forum posts 1 photos	Hi Chris, First, your carbide tips chip easily if you stop a cut with the tool still at the end of the pass and still touching. Carbide is generally quite brittle, so if, say, you are turning down a cylinder and you stop to check the diameter move the tool slightly to the right before stopping the lathe, or better still move the tool to the right to clear the work before stopping. Carbides often produce a rough finish if you do not take a deep enough cut, the tips producers should/will give details if you can find the makers catalogue. The problem for us amateurs is that often we want to take a small finishing cut to get an accurate size, then we get a rough surface and wonder what the, er, heck. So the conditions for using carbide are, use the right speed, have the right depth of cut and the right feed rate. All of which will seem a bit fast, a bit deep and a bit quick, and you may not have enough power for the right conditions, either. As a guide there is one tip that is very good for finishing but for 1/2" diameter in steel the range of speeds is 1800-7000 RPM, bet your lathe doesn't go that fast! Fear not, obviously you can use carbide, but they are not necessarily the answer to all metal turners problems. Oh, and just because industry uses carbide and now increasingly ceramics, it does not mean that they are good for you too. Unless of course you have fifteen horse motors fitted, but I think that might not be the case. HSS on the other hand is, with a few exceptions, the answer to most hobby metal turning. I feel that model engineers opt for carbide because they look at charts giving all sorts of angles and shapes for HSS and think how am I going to be able to grind that lot, well you don't have to. All a lathe tool needs to cut is a sharp edge. 7-10 degrees of clearance and rake will cut most things, maybe it will be too blunt for some metals and maybe it will wear a bit too quickly in some others but it will almost certainly give a better finish than you are getting at the moment., yes it will work even on brass! (Mr. moderator take note) Now to grinding, any old grinder will do, if you change those awful wheels that they come with. Those wheels are for mangling bits of old iron, not your precision tooling. You will need at least one "white" wheel (nothing to do with BNP policy) of perhaps 80- 120 grit. A coarser one as well, would speed up roughing your tools but you can manage with the one. If you can buy a grinder with white wheels fitted it might be safer, as fitting wheels to a grinder is an art in its self and can be a touch risky.(British understatement), most tool shops sell them but unless you know what you are doing get tuition first. Not rocket science but there are pitfalls to be avoided. The next thing to look at are the work rests, these need to be both rigid and adjustable. Some of the cheapest grinders have, at the best, flimsy work rests. All again is not lost because there are numerous designs for separate rests that would knock spots off the ones on even the most expensive grinders. Downside is that you might well need sharp tools to make one, Catch22?? It's a bit late for the next grinding course at SMEE, they are fully booked, but there must be a local club to you, where some kind soul can give you hands on tuition. Once you have the basic skills and safety glasses, you can experiment with shapes and angles, to see what works for you and your particular needs. Take all those drawings and angles as a guide, they are remnants of pre-war industry where maximum metal removal is all important, not the case with home use. It would not be me, if I did not blow the trumpet for Tangential/Diamond shaped tooling, so have a look at the web site for the Eccentric tools found at the top of the home page. There is a video which might open your eyes to the possibilities. Then you can look t this months MEW for plans if you want to make your own. You could also look at the great number of posts about the tools that there have been on this forum. Hope I have not bored you too much. A whole book, alright a chapter could be written about your requirements but not by me. I am sure someone will come back and say it is all bo**ocks, but works for me. Remember, for every twelve engineers you will get fifteen views, more if they are not feeling lazy. chris stephens
chris stephens	21/10/2009 01:56:49
1049 forum posts 1 photos	Just to add to the above, I am reminded that on another forum there was some debate about girnding wheels, where some disputed the analogy of grinding wheels and hand grenades. As some of you might appreciate a hand genade is not an explosive device as such, it is a shrapnel device with explosive as the energy source., in much the same way that a rifle bullet is not an explosive device, just powered by an explosive. Well a grinding wheel when spinning has an enormous amount of kinetic energy, and if it broke apart , you would have a shrapnel device. Any ATOs care to comment? I don't mean to put anybody off, just be careful with grinding wheels. chris stephens Edited By chris stephens on 21/10/2009 02:00:32
modeng2000	21/10/2009 07:56:33
340 forum posts 1 photos	I would second all that Chris has written, sound advice. The Tangential/Diamond tool has worked well for me and I wish I had had one sooner. John
Leadscrew	21/10/2009 10:41:00
1 forum posts	I too do not like spending money frivolously, but I purchased a Diamond tool from Oz, (which incidentally was posted as a commercial sample ~ no duty). It has done everything I've asked of it, although I have not had the need to use it for cutting a thread (to date). I'm using it on a Myford ML7 with QC toolpost and during repeated tool changes I just reload to the toolpost and away we go, it's on centre every time. Easy to sharpen, what more could you want. I concur with modeng2000's comment "Should 'ave had one sooner"
chris stephens	21/10/2009 11:58:37
1049 forum posts 1 photos	Hi John, Why, thank you kind Sir. One tries. Hi Leadscrew, If you don't like spending money, who does, well excepting the female of the species, why did you not make one. There is nothing too complicated about it, and once you have found how good it is, you can then buy a Pro. made one for durability. (Got to support the advertizers, you know. ) chris stephens
mgj	21/10/2009 18:34:40
1017 forum posts 14 photos	The one of grinding HSS which always puzzles me is the advice never to dip it in water to cool it. This apparently introduces cracksNwhich can lead to all sorts of dire things. not in my workshop is all I can say. Nowadays I do keep it cool by dobbing it with a wet paintbrush when clear of the wheel, right from the start. In the past I've dunked it when it was blue with heat. I'm sure that is all wrong, but I speak as I find. (I have only ever ground Eclipse, Sandvik or Cleveland bits. Once some chaep imported stuff and that is in the trash can) I think Chris advice is very sound. He and I have a habit of agreeing far too often. The tangential thingy looks excelelnt - no experience unfortunately. The only problem is that its too simple to sharpen and one might just live with sharpening that and leaving other bits - and one does need to be able to tackle them - screwutting tools, speciaist grooving tools drill bits and all sorts. So to back Chris, get Harold Halls book and get building a rest for an ordinary grinder. Even if you are a tipped man, and I am now, it will still be enormously useful - not least because if you have a green grit wheel you can sharpen all the blunt tips!. Perhaps I'm braver than Chris about grinding. If one fits the wheel with a proper arbor and spacer and uses the soft packing washers and cup washers on a wheel of KNOWN PROVENANCE one should be OK. First thing is to dress it properly and second thing is to remember that .001" is a very big cut grinding. However caution and goggles are good things. As for using carbide - I must say that I've read all the stuff about speeds and feeds, and it is, no doubt, very sound. I just use it exactly as I would HSS - never changed coolant either, just 20:1 dilute soluble oil for everything from cast iron to titanium. I have never had anything other than good results on a 6" Chinaman and a Super7B. However, I have never used cheap tips, and I have never used cheap tools. It is just that last time someone had an agony about finish with tips, it turned out that the tools were not giving him clearance
Tony Pratt 1	21/10/2009 19:29:29
2319 forum posts 13 photos	I too dip all my HSS tools in water when I am sharpening them as they can just get too hot to handle. In my nearly 40 years as a Toolmaker I had no problem with this practice and no one ever said it was detrimental [ although in theory I am sure it is !] I never dipped carbide in water after grinding. My latest practice at home is to rough with a tipped tool and finish with a nicely honed HSS tool, I believe I have arrived at the best solution for me. Tony
Ian Abbott	21/10/2009 20:12:46
279 forum posts 21 photos	A couple of comments. Years ago, a friend who owned a brass foundry had a wheel disintegrate. The flying matter embedded the pieces of his face shield and the grinder shield into his face. After a lot of surgery, they managed to rebuild his face and sort of save the sight in one eye, he lost the other. He took all the precautions, had all the safety gear. Since then, I never stand in front of the grinding wheel, always to one side, always wear leather gloves and face shield or goggles and never, ever trust a stone. I've had angle grinder discs shatter on me, but I always wear heavy gloves and keep the shield between me and the spinning round bit. And. I use a coarse open white stone to rough HSS and finish on a fine disc sander. You need to be careful though, as a disc sander can build the heat up way too quickly. Ideally, I'd like a proper tool grinder, but that 'aint going to happen unless the lottery comes up. This system has worked for years though and the old Randa gives as good a finish as I've ever produced on a modern commercial lathe. And, I always use water to dip HSS tools and they've always come out ok. Ian
mgj	21/10/2009 22:48:58
1017 forum posts 14 photos	Yes - I rather prefer those full face masks for anything like that. One can see rather better! I have a couple, one hangs up by the Quorn and one by the grinder, and I even use it when I am polishing.
chris stephens	21/10/2009 23:24:22
1049 forum posts 1 photos	Hi Meyrick, and others, As I got slated for saying something deemed to be outrageous dangerous before, I was trying to give advice that was not just sound but also "safe". Of course I am a little more cavalier when I am on my own, but I know my abilities and the risks. The risk , perhaps that should be one of the risks, with people unused to fitting wheels is that they think they only have to true the outer rim. More than once I have been given the task of stopping a grinder dancing about after the owner has "just put a new wheel on". If sharpening of a tool is too simple, just how is this a problem? Of course you can use tips at slower speeds, my Bantam only goes to 800 RPM, and I use them. When not using a Tangential, of course. Now, Meyrick, there is no reason two practical people should not agree on a regular basis! Unless they are talking about football or some other daft pastime. chris stephens
mgj	22/10/2009 10:37:49
1017 forum posts 14 photos	I agree about setting up a grinding wheel - one does HAVE to use the correct spacer and discs. And the grinder wants to be in reasonable nick too - and be bolted down. I must admit I am quite keen on face protection. I once picked up a single spark from an angle grinder. I was wearing goggles, so this spark had to have come off the wheel, hit my cheek, bounced under the goggles, hit the back face of the goggles and then bounced back again into my eye. Uncomfortable session later in the Addenbrookes and all was OK , but these things have a surprising aount of energy, in certain circumstances. Also the big face jobs don't mist up! Too simple - of course. Very obviously its an excellent device. Wish I'd heard about them earlier, because then I wouldn't have struggled to build the Quorn accurately. - chickens and eggs. Edited By meyrick griffith-jones on 22/10/2009 10:39:30
michael bird	22/10/2009 10:44:22
22 forum posts 9 photos	Hi, Having read the comments regarding tangential tooling, I have looked at the website and the video and yes I am ready to buy. However, I am very much a beginner and find it somewhat confusing as to what size I should order. I have a 6" lathe and its X dimension is slightly shy of 14mm, so I assume that the B16 is not for me. The A 9.5 is said to be suitable for 4.1/2" lathes - I am hoping that one of you learned gentlemen can advise me which size I should order. Mick Bird.
chris stephens	22/10/2009 12:16:31
1049 forum posts 1 photos	Hi Mick, Glad we have convinced you, but I am afraid I can't help on which size, but I am sure that the Ozzies can tell you, if you E-mail them the lathe type. Don't you have a workshop, though? I do and I find it quite useful for making things like tooling! Whichever way you go, home made or shop bought, i doubt you will regret it. If you do think about making one either from plans in the last MEW or say The Gadgetbuilder site, you will get more satisfaction than buying. Anybody would think I only have topic for conversation, but it is not true, I can talk about many things, just give me a few hours to think of one. Happy turnings chris stephens
mgj	22/10/2009 14:31:21
1017 forum posts 14 photos	Michael - don't worry about what it's "suitable for", because your toolholder may not be the same as his. Measure from centre height to the lowest edge of the tool holder (in its lowest position if you use a Quick Change type), and that will tell you the one for you. I use 12mm tooling on my 6" lathe and thats perfect for me, but my toolholder may be differnt from yours.. Just to damp Chris firework slightly, I can take a 250 thou cut on radius on a Myford at 600RPM, on a standard tool ...... its just the hot fingers and rough grinding it takes to get there thats the PITA. Edited By meyrick griffith-jones on 22/10/2009 14:34:10
Nigel McBurney 1	25/10/2009 22:59:15
1101 forum posts 3 photos	Hi I would advise turning with HSS,carbide tooling ,on small lathes you will get far better results and good machined finishes,carbide is ok for modern production with high power and very rigid machines,insert type chips tend to force the metal off into chips rather than cut it,Carbide is useful for roughing castings where there is sand and hard spots in the skin,I do use carbide insert tips on my colchester master when roughing out items made from steel bar as the the chip breaking grooves do their work and produce a pile of small chips which can be shovelled up rather than miles of stringy swarf which is difficult to manage.For grinding I would advise a 200 mm wheel as one day you may get a bigger lathe,and use bigger tool bits and it takes too long to grind them on a small wheel.When I worked as an instrument maker it was common practice to cool the HSS bits in water while grinding but do not get the steel too hot,quench frequently,
Chris Farbrace	26/10/2009 22:13:47
17 forum posts	Hi,very many thanks to everyone who replied to my posting,I shall be trying the diamond tool and hope to get the success that others are having.Regards,Chris Farbrace
Smike	29/12/2009 23:13:55
7 forum posts	Hi, could anyone give me a definite answer as to whether it is safe to use the SIDE of a grinding wheel (the normal ones that come with off the shelf bench grinders) for grinding drills and lathe tools? Or do I just use the front and end up with a hollow ground finish? Or do I replace the wheel with a different one? Lots of grinding rests and articles seem to use the side, but I thought this was a no-no. Thanks for your help, Mike.
mgj	29/12/2009 23:34:11
1017 forum posts 14 photos	I agree - lots of pix so I assume its safe. The problem is having dressed the side a few times would it not start to go taper? Thus making it awkward to get a straight edge - though there are edge cutting techniques to avoid that - but it would be difficult to sweep across a side face and still hold an even cut. Build a Quorn !. Save the offhand grinder for roughing, or tangential tools which appear to be an easy solution. Still that doesn't solve the drills and tapers problem.

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