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Member postings for Cabeng

Here is a list of all the postings Cabeng has made in our forums. Click on a thread name to jump to the thread.

Thread: Indexable tool holders
11/09/2013 20:38:05

Pah! Call that swarf?

My record is over eight feet of tightly coiled stainless steel, that's real swarf.

Neil

Something like this?....

6.7.jpg

Yes, that's swarf. Nasty stuff, gets into lots of places you wouldn't want it to get into ..!!! I'll stick to chips with everything!

Something I forgot to mention, another check for a carbide tip cutting correctly, as intended. Watch the formation of the chips (or swarf, if you haven't got it right!), and you should see the waste material being directed to the left of the tool, in the direction of the un-machined surface. If it's going the other way, right and towards the newly machined surface, then a) something is wrong, and b) it can cause poor finish if it contacts the newly-cut surface.

11/09/2013 18:18:35

Hello Martin, thanks for the answers. 1 - 3 bode well for success with carbide tools.

Re 4 - I was hoping you would be able to provide the designation for the tips themselves, rather than the toolholder shapes. Something like Sumitomo CCGT060202-NSC T1200A. It's the -NSC bit that's of particular interest as this identifies the geometry of the chip breaker arrangements moulded into the tip, which in turn determine the ranges of feed and depth of cut for which the tip is suitable.

If you haven't got that information, your answer to 6 provides some guidance - you were cutting on the edge of the tip's envelope, or a little out of it. Have a look at this diagram, cribbed from a Sandvik publication, I think:

chipping.jpg

Tips are designed to produce comma shaped chips that are easily removed from the machine, and don't clog things up, and they would produce such chips if being used within their intended feed and depth ranges. Longer spirals suggests you're slightly outside the range for the tips you have. That's generally ok, a bit outside the envelope (in any direction) works fine in my experience, but as you are having some difficulties it would be better to have the tip cutting within it's range for now. So adjust feed and depth until you find a combination that gives comma chips.

Now to question 5 - mmm, no experience of those devices, but I can see a potential problem if either the lathe isn't perfectly level, and/or the chuck doesn't hold perfectly concentric - the tool tip could be off centre height. Carbides can be VERY touchy about centre height - get them even slightly above and you're in trouble as they'll be rubbing as well as cutting, which gives a poor finish. You might get away with ever-so-slightly high with a sharp HSS tool, but not with a carbide tip, as they don't have sharp edges. Sumitomo specify +0.000"/-0.0015". That's for a front mounted tool of course, reverse them for one in the rear tool post.

If you have a height gauge I would suggest that you use that for now, and aim for a thou or so below centre. But one thing NOT to do when setting a tool to height is to use the old trick of trapping a rule between the tool and the work - this kills carbide tips, stone cold dead. Micro-cracking again. Never let a tip contact stationary metal, they don't like up 'em, Mr Mainwaring, they don't like it up 'em.

11/09/2013 12:47:09

Martin:

Use of cutting oil. No, definitely not. Carbides need either a full flood of coolant, or nothing at all.

Dripping/brushing it on risks causing rapid temperature changes at the tip, which can lead to micro-cracking of the carbide and premature failure. Also the temperatures that can result when cutting without full flood can cause the coolant to dissociate into unknown chemicals - better not to risk that!

11/09/2013 12:41:43

Turning to rigidity (and this is bound to rattle a few cages!) - if a machine/tooling/job setup is rigid enough for HSS, then it's rigid enough for carbides!

The need for rigidity depends upon the forces generated at the tool tip, which depend on the force needed to shear the material (referred to as the specific cutting force), the depth of cut, and the feed. For a given material, depth of cut and feed, it is INDEPENDANT OF THE TOOL MATERIAL. Taking ten thou. off steel at 0.004" per rev. will require the same force at the tool tip whether the tool is HSS or carbide.

In fact, in certain circumstances, the forces with a carbide tool will be LESS than those with an HSS tool. Say your Myford has a 1h.p. motor and you want to shift the steel as fast as possible, using the full 1h.p. (I'm neglecting power and gear train losses here) An oft-quoted and reasonable figure is 1 cu.in. of steel per minute per h.p., so you can do this in one cut at lowish speed using an HSS tool, resulting in a certain force at the tool tip, trying to deflect it downwards.

Alternatively, do it with carbide in 3 cuts at one third depth of cut and three times the rpm, still removing 1 cu.in. of steel in one minute (neglecting time to wind the carriage back, of course!), still using 1 h.p.

Now: Power = Torque x RPM

And: Torque = Force x Radius

Hence: Power = Force x Radius x RPM

And since the RPM is now three times greater than before, the force at the tool tip is only one third of that required to shift metal at the same rate as the HSS tool.

So, assuming that Martin and his machine can get good finish on FCMS with HSS, speed and rigidity are not the causes of his poor finish with the carbide tools. If his S7 is in good condition, then I know for sure that 700 rpm on 1" diameter FCMS is fast enough, and the machine is rigid enough, to give good results. We need to look elsewhere for the cause of his difficulties.

Some questions for Martin:

1) Is the machine (bearings, chuck, slides, everything) in good nick? If not, you need to fix it! Not for carbides, but for all cutting tool materials.

2) Do you get good results with HSS? If not, put away the carbides until you've sorted out things for HSS.

3) Are you an experienced user of your lathe, or still near the bottom of your learning curve? If the latter, see 2) above!

4) Do you know the exact details of the tips that are fitted to your tools? If so, please advise. If not, throw them away. Use of an inappropriate tip is, in my experience, the commonest cause of poor results for model engineers.

5) How do you set the tool to centre height?

6) Can you describe the swarf? Not bothered about colour, it's the form that matters, it will give clues as to whether or not your tool is cutting within it's design envelope. Very short comma shaped chips, short spirals less than say 10mm long, longer spirals, continuous spirals, wirey flat strips with a tendency to wrap themselves around everything?

11/09/2013 12:40:59

Martin/Thor/Clive - I might end up regretting starting on this, but here goes anyway.....!

The comments re speed and rigidity w.r.t use of carbides are commonly expressed, but they're not the whole story.

Speed is easily dealt with - carbides will cut quite satisfactorily at low speeds. Very low speeds - if they wouldn't do that then they wouldn't be capable of parting off, facing off, or drilling.

I suspect the idea that they need high speeds originates from manufacturers' recommendations that to improve finish one should increase the speed - someone has heard this in the past, and it's been handed down ever since.

Well, the recommendation is correct, but it's being taken somewhat out of context. A common cause of poor finish is the formation of a built up edge (BUE) on the tool tip, caused by material from the workpiece becoming welded to the tip. The formation of BUE depends on the material being cut, the material of the tip, and the temperature at the interface between the two. The normal recommendation is to increase the cutting speed, which increases the temperature at the interface and takes it above the region where welding can take place.

Industry isn't interested in going slower, so that recommendation would not be welcome! We, on the other hand, very often can't increase the speed sufficiently. So do the opposite, and slow down! The interface temperature drops BELOW the welding range, and good finish results.

To further illustrate this effect, we've all seen it many times, albeit without realising what's happening. Imagine facing off a 4" disc - good finish at the outside where the speed and temperature are high, then it falls off part way across as the temperature enters the critical region and BUE forms, and comes back to good when the speed and temperature falls below the critical region. If you were to double the speed for another cut with identical depth of cut and feed, you would find that the 'poor' finish region now occurred at half the diameter.

As far as the tendency to produce BUE goes, somewhat crudely and arbitrarily...

Aluminium/HSS - AAAAGH!

Steel/HSS - Not so bad

Steel/Tungsten carbide - Better

Steel/Titanium carbide - Good

Steel Titanium nitride - Gooder. Sometimes.

So the 'need for speed' is not intrinsically linked to the carbide itself, it's linked to the avoidance of BUE. The suggestions to increase speed will have an effect if BUE is the cause of the problem, as long as you increase it sufficiently to get out of the BUE region, and that depends on the actual tips you have. If you're comfortable with the S7 at top speed, go for it, but if you're not used to this, be aware that the carriage does tend to approach the chuck surprisingly quickly!

Clive's suggestion re increasing depth of cut - yes, try that, as taking more metal off will increase the interface temperature and might help you get away from the BUE region. But as far as not liking fine feed is concerned... well, that depends on the tip. A new Sumitomo CCGT060602 in T1200A titanium carbide will take off less than a thou. at 0.002"/rev, but one designed for turning tyres on 12" scale loco wheels would need a bit more than that!

You could also try going slower, of course, but not so low as to need back gear.

But when trying different rpm, keep the depth of cut and feed the same, otherwise you'll be introducing additional variables into the mix, each of which will affect the interface temperature, and possibly the finish that results. Which would lead to confusion.

Now the website says it was too long, so the bit about rigidity comes in the next posting!

Thread: Drilling accurate depths
31/05/2013 10:23:57

I've put 2 photographs in a new album (drilling to depth in lathe) to show how I do this - you might not be able to adopt the method directly (depends on what kit you have - I have a DRO on the lathe, plus a Dickson toolpost that has 3 mounting faces, which combine to make it very easy) but it might give you some ideas.

It's simple, quick and effective. Put a bar in the toolpost, with sufficient protrusion to contact the nose of the drill chuck. Put the drill point up against the work, lock the tailstock and barrel , then move the saddle to the right until the bar contacts the front of the drill chuck, as per first photograph.

Now move the saddle to the left, a distance equal to the required depth of drilling - second photograph. (DRO, saddle handwheel, DTI, ruler?)

Lock the saddle, drill until the nose of the drill chuck touches the bar again, and you've drilled to depth. But be careful when touching the bar, a screw feed tailstock can push a locked saddle along if applied with enough enthusiasm, and that would mess up your pre-set depth.

Thread: Centreing a rotery table
10/09/2012 17:22:23

Here are some further alignment suggestions, with photographs uploaded to a new album.

First photo:

My Vertex 6" RT is fitted with an adaptor with a Myford spindle nose, which itself has been centred on the RT so that the spindle nose is accurately located relative to the RT's centre or rotation.

The RT is placed on the mill table, but not bolted down. With an accurate bar held in both chucks, the RT can then bolted to the mill table, centreing accuracy being dependant on the accuracy of the chucks, of course. WIth collet chucks, the accuracy should be very good.

Second photo:

Same idea, but this time to align a mandrel with the vertical spindle - grip the mandrel in the spindle collet chuck, then bolt the angle plate to the mill table. The component (in this case the regulator bush for my boiler) can then be drilled and tapped.

Third photo:

On the right is a 3MT blank end arbor with two diameters machined on it, 19 and 20mm, to fit the largest sizes of ER32 collets. The Omnimill vertial spindle is bored 3MT, so this fits directly in the vertical head. Why two diameters? Because the Great Law Giver Murphy has decreed that whenever alignment is required, one of those collets will already be in use elsewhere!

The various tapered mandrels are used position pre-drilled holes under the vertical spindle - mandrel in a collet chuck in the vertical spindle, poke the tapered bit into the hole in the workpiece, then clamp the work to the mill table.

The two methods work well in combination - use the 2-chuck method to centre the RT, remove the chuck from the RT, substitute the faceplate, then use a tapered mandrel to align the hole and its surrounding metalwork on the faceplate - clamp the work to the faceplate, and everything's set up for milling around the hole.

Thread: Chip Tray for Myford Super 7
01/09/2012 01:25:47

Yes, it does, I have one on my Connoisseur.

Thread: Strange Noise from Myford Super 7+
10/08/2012 01:12:16

Andrew: RDG have a number of items that are are not yet listed on the website, so it would be worth giving them a ring and asking the question.

You could also ask them to measure the length of the main body of the eccentric shaft, which could be compared to that of an S7 - 2.566". The result might be interesting.

John Manning: temperature changes won't affect the clutch assembly as both the operating rod and countershaft are made of steel, so they will both expand/contract by the same amount.

09/08/2012 01:36:21

Andrew Moyes wrote:

I have just brought into use a new Super 7 Plus bought in the Myford closing down sale. Actually, it was made in 2001 and run as a demo machine at exhibitions but appears never to have cut metal

Mine was very similar provenance - I bought the long bed Connoisseur that was displayed at shows. And a total dog of a machine it turned out to be! It had never been run, which was just as well, since it vibrated so badly that no-one who heard it run would ever have dared buy a Connoisseur! So it wasn't just the 'siezing' problem that I've had to deal with, to that we can add:

Rattling, eccentric and wobbling countershaft pulley, motor out of alignment, wobbling motor pulley, motor clamping arrangements rattling, main spindle pulley wobbling and rattling, leadscrew bent, tailstock out of alignment in two planes, various grub screws loose - to mention just some of them. Net result - the machine was unusable as bought. Overall, I've formed the conclusion that the demo machines were thrown together, never test run, and perhaps even never intended for sale. At least, not before they'd been back into works for sorting out.

I've stripped it so many times that I can now take apart the spindle, countershaft, clutch and motor assemblies in less than 15 minutes! At least that's made me very familiar with the components of a big bore spindle assembly.

The spindle cannot be displaced left relative to the headstock casting itself by more than a midges nudger, otherwise the spindle would lock tight in the front bearing bush.

Changing the distance sleeve won't make any difference to where the spindle sits, the only effect of making/installing a longer one would be to shift the angular contact bearings leftwards to achieve the correct spindle/bush clearance for the front bearing, and push the gear sleeve left as well, thereby affecting the mating of the gear sleeve with the tumbler gears.

The spindle pulley then sits and runs against the right hand edge of the distance sleeve - since this abuts and is clamped against a step on the spindle, the pulley will sit in exactly the same position, once the front bearing clearance has been adjusted.

You say: The bronze gear on the end of the pulley does not fully engage the larger of the two gear on the backgear cluster by about 1/8", by which I take it that you mean that the large cluster gear sits to the right of the pulley gear, and overhangs it by 1/8", running into the groove between the end of the gear teeth and the bull wheel drive collar.

So, since the pulley is more or less correctly located (it must be, unless there's something else drastically wrong, and I can't think what that might be), your problem must be that it's the backgear cluster that's displaced to the right. Since the cluster gear position on the eccentric shaft is fixed, the eccentric shaft must be displaced to the right.

Have a look at the backgear operating lever - it should sit close to the front of the headstock casting, and, of course, the detent should engage with the holes in the casting. Since anything wrong there would be immediately obvious, I guess it's ok, so look at the protrusion of the eccentric shaft from the operating lever - there shouldn't be any, it should be flush.

If it does protrude, that will be the problem, fortunately it's easy to fix. There are two grub screws securing the lever to the shaft, undo them - they're bloody awkward to get at! Then insert a flat bladed screwdriver into the top detent hole and twiddle it round - there should be a slotted head grubscrew down there, that fixes the longitudinal position of the eccentric shaft by engaging in a groove in the shaft. Loosen the screw, so that the shaft can move, but keep a little turning pressure on the grubscrew. Push the shaft to the left whilst gently turning the grubscrew against the shaft and you should feel when the groove gets to the screw as it will suddenly turn and enter the groove. Keep turning the grubscrew to fully engage it, but don't tighten it onto the shaft or it will prevent it from rotating. Then engage the gears with the spindle, as per the instructions in the manual, re-fit the handle and tighten the grub screws.

Now, if my analysis of the problem is correct (here's hoping!), the cluster gears should align correctly and you can re-adjust the position of the bull wheel on the spindle. There should be a little clearance to the pulley, the book says 0.005", but I've not found this to be critical.

But if it's not fixed, there's one other possibility that I'm aware of, but this has to be very unlikely - assuming that the S7+ big bore has the same components as the Connoisseur, which I think it does, except for the pulley itself, your machine might have the wrong eccentric shaft fitted! The big bore headstock has many detail differences to the old S7 version, one of which is that the backgear cluster sits further to the left in a big bore machine than it does on an old S7, so the eccentric shaft seems to be longer. Can't say by how much exactly - I measured the shaft from my S7 when I had it dismantled for the poly-vee conversion, but I haven't yet measured the shaft from the Connoisseur - but I think, from comparing my machines, that it's about 1/8", so you might (unlikely, but might) have an eccentric shaft from an S7 in there. On the other hand, given what I've learnt about Myford's assembly quality on their demo machines, I wouldn't be entirely surprised.

08/08/2012 03:12:08

Bob:

I've had (have?) the same problem with a Connoisseur - I don't have a definitive answer as yet, but this posting will at least let you know that you are not alone! Apologies in advance for the length of this one.

On my machine, the spindle would slow dramatically, accompanied by the squealing noise. But knock out the clutch, and the spindle would rotate freely thereafter. The noise is the belt slipping - on my machine, I think (but can't be sure) that it was the primary drive belt that was emitting the noise, the spindle was siezing, but not always completely. In fact, I'm not sure it did ever actually stop completely of its own accord, as one's inevitable reaction was to knock the clutch out pdq.

It would do this every time I tried to run it from cold at speeds of say 1500 rpm upwards, but if I warmed it up gradually, it would behave itself. Then having done some work at say 2000 rpm, leave it for half an hour, then go back and start it at 2000 ... and the bloody thing would try to sieze again!

I've had the spindle out a number of times, and was surprised to find that despite Myford's much-vaunted scraping of the front bearing bush, the spindle was only contacting the rear half of the bearing, which did indeed show some signs of ... how shall I describe it ... well, wear, or rubbing, or slight siezing. I did give the bush a very gentle rub with 1200 wet & dry to clean it up, but that didn't seem to have helped. And yes, I was VERY careful to ensure that I didn't leave any nasties in there when I re-assembled it!

I adjusted the bearings several times, according to Myford instructions. Not the ones in the manual, but as more recently recommended by Myford. I've put a copy in a new album, Myford spindle adjustment. But I never seemed to absolutely cure the problem. So I decide to kill it or cure it - use the machine until it siezed solid, then at least I could identify exactly what was siezing, even if I did have to take it apart with a hammer!

I used it to do a lot of cast iron machining to convert my S7 to poly-vee drive on both primary and secondary drives, so it did a lot of heavy cutting (four castings, plus the original Muford clutch pulley), but never got above about 800 rpm. Since that exercise, it hasn't siezed once, despite being subsequently run up to 2500 rpm a few times! So the question is - did that heavy use 'bed it in' and eliminate the problem, or is it still there, waiting to appear again? I don't know, and it will take some time, and a lot of use, before I get any confidence that the problem has indeed gone away.

I'm tempted to take the spindle out again, and have a look at the bush. But I'm reluctant to do that whilst it seems to be behaving itself.

It turns out that poor scraping of the front bush is not unusual - I had to remove the S7 spindle to fit the poly-vee conversion and found that spindle had only been running on the front half of the bush for nearly 40 years! Machine made in the second half of 1975, been in my possession since new, and never siezed, even though it's spent most of its life on top speed. But there were some signs of distress in the bush, including one score line around the bush, but nothing on the spindle. As before, the score was removed with 1200 wet & dry, the machine re-assembled, the bearings adjusted as per the latest instructions, it went straight on to top speed, and was left to run for several hours. No problems with the S7, and it takes good heavy cuts without chatter, so the bearing adjustment is obviously not too slack.

None of which is of much actual help, I'm afraid. All I can suggest is that you pull the spindle out and inspect the front bush to check its condition, and the state of the 'precision scraping', see if you have the same features as found on my machine(s). Pay particular attention to the top and rear section of the bush, as this is the area that takes the belt and cutting loads. Then re-assemble and adjust the bearings as per the revised instructions.

You can easily check that the bush is lubricating adequately - clean the inside area of the headstock casting, adjacent to the bull wheel, then fill it up and run it, oil should run out down the headstock casting. Mine suffers from incontinence, there's always an oil puddle in the tray to the left of the headstock raisning block.

Oh, what belts do you have on your machine, vee or poly-vee?

One other snippet - I know someone else who has a Connoisseur, and he says that he never runs it at high speed from cold, always runs it up gradually, letting it warm up. I have never been able to find out exctly why he does this, he seems a bit cagey about it.... maybe he has the same problem? Or maybe he's a just member of the Royal Society for the Prevention of Cruelty to Myfords? It's not something I've ever found necessary with the S7, to which I have been unremittingly cruel over the years.

Thread: DRO kit 600-82948 from Newall on 1969 Myford Super 7
26/05/2012 02:02:54

Newall photographs sent to you directly, unfortunately they add up to about 5Mb... sorry about that!

Another apology - there isn't a photograph of the saddle clamp in the S7 album. Well, there wasn't, but there is now, I've just uploaded one.

25/05/2012 01:57:42

Jon: thanks for the comment, most kind of you!

The scale guards are cut away at the bottom to allow access to the gib screws, which are lower than the Microsyn scale, so no access problems.

Loss of saddle travel to the tailstock - yes, I too was concerned about that when I did the original installation, but it's never been a problem over the years that I've had the Newall.

The original guard does bump into the tailstock (actually quite convenient for pushing the tailstock to the right!) but does unfortunately knock the c**p out of the paintwork on the tailstock. To stop this happening on the nice new blue one I fitted a bump stop to the saddle - new photograph added to the album.

The protrusion at the rear of the cross slide has never been a problem, other than occassionally knocking over oil guns parked behind the machine! The original guard on the S7 is steel angle, so solid and substantial - the Newall guard is a light extruded aluminium thing, not so substantial. Time will tell whether or not it stands up for itself.

Oh yes, another point for Olaf - you might have to file away some metal from the underside of the cross slide scale support to allow it to pass over the oil nipple for the front shear.

And you'll loose the clamping device at the back of the saddle. One solution is an excellent clamp that can be seen in the S7 album, at the front of the saddle. This is so good and convenient that it won't be long before I make another one for the new machine.

24/05/2012 15:05:52

Olaf:

I bought and installed a Newall DRO last year, about October 2011. Different kit as mine was a long bed machine, and I had specific requirements for the diplay mounting arrangements, but the installation of the scales should be exactly the same.

There are some photographs of the original installation of a Newall onto an S7 in one of my albums - not exactly the same as the Newall arrangement, but the photographs show the installation on which Newall based their design.

I have some photographs of the more recent installation, I'll upload them later today, and I also have some Newall piccies as well. I won't upload these as they are strictly speaking Newall copyright, but if you send me a PM I'll send them to you direct. Between them, they should make things clear.

A few points:

Make sure you have the correct scale and guard for the cross slide - Newall sent me the wrong one! They insisted it was correct, but it definitely was not right - too short for a long cross slide machine, would probably have suited an ML7.

The right hand side of the cross slide has to have I think 3 holes drilled and tapped into it, for which the cross slide needs to be removed. It can be done with the slide in situ, remove the tailstock and wind the saddle to the end of the bed for access, but you'll still have to make up an extended drill and extended tap wrench to gain sufficient reach.

When installing the cross slide scale guard, ensure that it sits slightly below the top surface of the cross slide to avoid interfering with anything that might get bolted to the tee slots.

I think (it was only 7 or 8 months ago, but I can't remember - it is said that short term memory goes first!) that the guard for the bed scale is pre-drilled at the same centres as the taper turning attachement holes in the bed. You'd better hope so, as drilling for the bed scale guard is awkward if the lathe is installed backing onto a wall - my S7 was like that when I did the original installation. Definitely a tricky job with the lathe installed backing up to a wall - difficult to position accurately whilst effectively standing on your head, and some drilling machines won't get in there - the larger of my two Makita battery drills was too long, fortunately I had a shorter one that would just do it.

The support brackets for the scales are really easy to use, all should become obvious if you have a dummy run with them. But do take some trouble to get the scales and reading heads properly and accurately aligned so that the head runs freely on the scale and doesn't impose any side loading on it - it'll be ok if it's free at both ends of it's travel, but do check carefully as the scales don't like being bent.

Also, take some time to think about where you mount the display, and how you run the cables to it. Avoid leaving them just hanging loose in the mud, blood and swarf, they would get very messy as time goes by. And you don't want them somewhere you can drop chucks, faceplates, vertical slides etc. on them - replacing a cable means replacing the reading head, and that's not cheap.

Funnily enough, replacement scales are relatively cheap - I damaged one of about a metre length installed on my milling machine, it was only GBP80 to replace it, I had expected much more, and it arrived within a couple of days. On the upside, I now have a very good supply of precision 5mm diameter steel balls!

Other than that, installation is straightforward. Any questions, send a PM.

Thread: Leaking Oil From Myford super7 Plus Big Bore
28/02/2012 00:42:02

Bob: wlecome to the dripping big bore club! Mine does the same, also drips oil from the headstock (look under the lathe, on top of the raising block) and the right hand countershaft bearing, although this oozes out of the end of the housing, around the operating handle.

Is the oil completely clean, or does it have some black stuff in it? If so, that's almost certainly a contribution from the front spindle bearing.

It's certainly an incontinent machine - my old faithful S7B doesn't do it anywhere near as much - but maybe that's because I don't oil it as often as the new one!

Thread: Sumitomo insert help
24/02/2012 02:38:09

Well MAC, it might be worth thinking about buying a new toolholder as well! I suggest that for three reasons:

1) If you happen to buy a box of 8mm tips just before the holder wears out (and they do, unfortunately), you could be left with a load of expensive bits of carbide that you won't be able to use because you won't be able to replace the toolholder.

2) There's another holder available for the CCGT tips, one that uses the other two corners, the ones with the obtuse angles, so you get twice the number of cutting edges for the same cost! It's designation is SCRCR for the right hand cutting version. Unfortunately, the toolholder is no longer available for 8mm tips.

3) Nobody other than Sumitomo makes 8mm tips, so there wouldn't be any opportunity to use alternatives, should the urge or need come upon you. 6mm & 9mm are standard sizes from many (if not all) manufacturers.

HB Cutting Tools can supply German manufactured holders at about half the price of the Sumitomo items - I just changed to 6mm tips and bought 4 of these holders (Right hand, left hand, right hand obtuse and neutral) from them, £28 each plus VAT, although I think the obtuse one was a bit more pricey. I've only just got them, so it will be several years (I hope!) before I know how long they'll last, but HB assured me that these were items that they sold into industry, and that I wouldn't notice any difference.

Maybe of interest - I've used the Sumitomos for many years on a Myford S7B PCF machine with VFD drive - it loves 'em, and shifts metal at an amazing rate. 2300 rpm on 1" FCMS is fine, the lathe hasn't been on the slow speed range since I got them. But watch out for the chips, they go ballistic!

Oh, and if anyone tells you that they don't like interrupted cuts.... don't believe them. The trick to making the tips survive interupted cuts is to cut DEEPER, e.g. 1.25" FCMS hex bar down to round in one cut.

23/02/2012 01:22:13

I have both those Sumitomo tools, albeit with slightly different designations - SCLCR1010-03S & BBPT 210R 303. They've given many years of satisfactory service, and consumed a lot of tips in their time!

I think the BBPT designation has indeed been superseded (it may have been a Sumitomo designation), their recent (2008) paper catalogue uses the ISO designation, which would be S10K-STUP R. Not exactly the same, the only difference is in the tool ength - the BBPT is 150mm long, the S10K is 125mm long.

The catalogues lists exactly the same tip for the S10K as I've used for many years in the BBPT- TPGT110302LW in Sumitomo T1200 grade, and have never felt any need to try anything else. I can recommend these tips wholeheartedly, superb finish and not prone to chatterring.

For the SCLCR1010 - that looks longer than the one I have, in comparison to the length of the boring bar, maybe that's down to the 03 code as opposed to 03S on mine. But the tip size looks the same in proportion to the size of the shank, in which case it could be an 8mm tip. I've always used Sumitomo CCGT080202N-SC, T1200A grade, and again wouldn't use anything else.

But check the size of the insert by measuring the length of one edge. The 8mm tip was not an ISO preferred size, a special for Japan I think, but that was what was being sold when I bought my tooling from the chap who first started selling them to model engineers - Ian somebody? Bought them at Stoneleigh umpty-one and a bit years ago.

The 8mm tips are still available, I bought some a few weeks ago, but they have to be ordered from Japan. The same cannot be said for the toolholder for the 8mm tips, Sumitomo don't make them anymore. As I found out recently when my toolholder went past it use by date and had to be replaced.

If you have the 6 or 9mm tip (actual sizes 6.4 and 9.7mm) , the inserts you require would be CCGT0602N-SC T1200A or CCGT0902N-SC T1200A respectively.

T1200A is an uncoated cermet grade, the N-SC part of the code refers to the design of the cutting edge and chipbreaker. For the TPGT boring bar inserts, the W designation is the part of the code that specifies the edge and chipbreaker shape.

I obtain my inserts and tooling from:

HB Cutting Tools (Ormskirk) Ltd.

Unit 2, Langley Court

Higgins Lane Estate

Burscough

Lancs

L40 8JR

Tel: 01704 897722

I don't know how they would compare with your Mr. Carter, I paid £4.70 +VAT each, buying a box of 10 inserts. The bad news is that they'll only sell them a box at a time - but who wants to buy one on it's own anyway? Break it, and your stuck until the next one drops through the letter box - better to have a box of 10 on the shelf, then you can get right on with the job, and order another box when you're down to your last two inserts!

Thread: Taps & Dies
05/10/2011 01:15:50
From Adam Gregory: "Just my luck to get a duff one."
 
I suspect you might have to be very lucky to actually get a good one!
 
I've put some photographs in an album, but be warned -these are not for the faint-hearted!
 
First picture - a montage of nested taps. One might reasonably expect that the threads on each of a set of taps would match, but t'ain't necessarily so. The carbon steel 5/32" x 40 taps do fit together beautifully, the same cannot be said for the metric taps, despite them being ground thread HSS from a supplier to industry, and not cheap. Additionally, they don't bear any resemblance to a metric thread profile.
 
Second picture - a thread cut in the lathe using a die in a tailstock die holder. Felt very strange when cutting the thread, subsequent inspection with a lens showed the thread WAS somewhat strange.
 
The third picture shows the die in question mounted on a properly cut thread - I think you can see why it cut a strange thread when held by the tailstock. Again, ground thread HSS.
 
Fourth picture - the teeth on some ground thread HSS dies, bought to go with the taps of the first picture, but a different supplier. Looks like they were ground with an angle grinder. Macbeth's witches probably had better teeth!
 
Lest you think this unusual, have a look at the BA dies in the fifth picture, another supplier. These are just 2 examples rom a 0 - 10 BA set of taps and dies - NONE were usable. The supplier offered to replace them - REPLACE THEM WITH WHAT? MORE RUBBISH? Oh yes, ground thread, HSS again.
 
And if you want the really bad news it's that, with the exception of the HSS taps, all the bad examples came from sources that have been mentioned on this thread. And I have examples from some that haven't yet appeared!
 
The first (and obvious) moral of the story is, of course, caveat emptor. The second is that if you're having difficulty with getting a good thread, your difficulties could well be caused by the tool you've been using. And the third is that paying more for a tap or die does not necessarily guarantee better quality.
 
Since those unsatisfactory experiences, I will only buy taps and dies with the manufacturer's name on the tool. If he doesn't put his name on what he makes... well, you can draw your own conclusions as to why he doesn't. That's the manufacturer's name, not the seller's. I stick to Apex (the 5/32" taps are Apex, from Kirjeng - never sold me a duff one yet), Presto, Dormer and Lyndon. And even those go under the microscope before being put into use.
 

Thread: myford super 7 mk1
15/09/2011 00:42:38
Des:
 
Another possibility is that the pulley has broken loose from its inner bronze bush. I know of two machines where this turned out to be the reason for the pulley rotating without driving the spindle.
 
Not a disaster, after dismantling just loctite the bush back in place, re-assemble, adjust the spindle as already mentioned, and it's fixed.
Thread: Myford Connoisseur Countershaft
08/09/2011 13:54:49
As I mentioned on the Myford sale topic, I bought one of Myford's 'show' lathes, the long bed Connoisseur lathe. It had never even had any oil in it's bearings, slides or gearbox, so it's effectively a new machine. But there's a problem with it, something I haven't come across in 40 years of S7 ownership and usage, so I'm hoping that someone here might have some suggestions. Long description of the problem follows!
 
After oiling everything up I started off by giving it some gentle running in, just letting it run whenever I was in the workshop doing other things, gradually increasing the speed at which it ran, working it up to 2500 rpm over a couple of weeks. It's not cut metal, it isn't even bolted down as yet.
 
The machine has developed a very distinct (for distinct, read quite loud, and very annoying!) clattering from the countershaft, originating from the area of the left hand bearing. It sounds as though the balls in a bearing are rattling around, a sound I'm familiar with from my youth, when car alternator front bearings would pack in, identifieable by putting the business end of a screwdriver on the housing, and the left ear to the other end!
 
The sound is only present when the countershaft is turning, i.e. when the clutch is engaged, and it's affected by belt tension - slacking off the spindle belt can eliminate it, but only by slacking off to such an extent that the belt is very loose.
 
It's far less noticeable when the machine is running in reverse, it even disappears at times, and when running forward it's worse with the belt on the left hand section of the pulley.
 
If it's been running in reverse, and is in nice and quiet mode, switching to forward without touching either the clutch or belt tensioning levers will usually (but not always!) result in it running quietly in the forward direction. But then disengage the clutch and re-engage it and the clattering invariably returns!
 
I suspect it's the thrust bearing but I'm not even sure that a Connoisseur has one. It must have, but the problem here is that Myford don't seem to have ever updated the manual, so the only reference I have is the S7 drawing in the manual supplied with the machine. This shows a thrust bearing (99 on Drawing Q), a collar (100) and a circlip (101) - the collar and circlip should be visible between the bearing housing and the left side of the countershaft pulley - and on Ye Olde Greye S7B/PCF machine they are indeed visible.
 
But they're not present on the Connoisseur countershaft, so something's been changed, but as I know not what at the moment I'm a bit wary of starting to pull the shaft for examination. So, before I resort to drastic action...
 
1) Has anyone out there come across a clattering countershaft on an S7?
 
2) Did you find out the cause, was it the thrust bearing?
 
3) For anyone else with a Connoisseur, have you experienced a similar problem?
 
4) Has anyone ever dismantled a Connoisseur countershaft, and if so, exactly where do I hit it with a big hammer?!
 
All very annoying and frustrating, so perhaps big hammer, should be changed to BLOODY BIG HAMMER!
 
 
 
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