ML7 Collets & General Update on Lack of Progress.

I've got some of those :-) The holders are OK but the screws amazingly soft.

Brian,

Why not just mill the holders down? They are after all adjustable an you are just increasing that adjustment range by 1mm or so. That wa you don't need to modify tools whenever you buy a new one.

Regards,

Garth

-- DR_

----------------------------------------------------------------------- DR_G's Profile:

this thread:

Tony,

I have a contact at work who represents Sandvik, and he supplied m with the tool and inserts for the materials and speeds I specified. A I said, the establishment I work for does aerospace related machinin research, so he knows what he's on about!

So far I have found it much better than the steel tools I wa practicing with before.

Cheers,

Garth.

It seems to work extremely wel

-- DR_

----------------------------------------------------------------------- DR_G's Profile:

this thread:

Richard,

Thanks for your comments - they are much appreciated.

Regading the insert vs steel tools, even though I am a complete novice and have only 'practiced' on various materials, everything I have don so far has confirmed the notion that a beginner like me is going to ge far more consistency of results by using replacable tips, than whe using self-ground HSS. How for example would I know that two seperat machining 'trials' gave different results because of feeds/speeds o because I'd ground the tool myself, to a slightly different geometr than the preceding operation? Maybe I am thinking about this too muc and should just get on with something!

Regarding collets - I agree with you totally that the best way is t get stuck in and do something useful! I am simply trying to take advic from several of the lathe books I was recommended to read, regardin 'essential' or very useful accessories. There is nothing worse tha having to stop a job half way through because you don't have the righ equipment! I intended to use the collets to hold milling cutter because I would like to practice a bit of milling as well as turning. could well be incorrect, but I think I need collets to hold the millin cutters?

Cheers,

Garth

-- DR_

----------------------------------------------------------------------- DR_G's Profile:

this thread:

Garth, you obviously want to take the more difficult route. A couple of small issues you might want to consider with your method; neither of which is a complete stopper if you feel the advantage is worth it. Most of the actual holders for the QCTP if it is the Dixon type are extremely hard, at least all the holders (dozen or so) I have for my two posts are. You would need to grind rather than mill. The second issue is that you are removing 1mm from the lower land that supports the tool and provides the stiffness during the cut. These holders vary in land thickness so I can't tell if that would be a problem with your particular one. Certainly on some of mine (cheap copy) it would leave the land fairly thin on the others it would be OK. Unless you want the ability to put the edge significantly below centre, on some of my 10mm tools I only needed to remove about 0.020", so not so drastic.

One of the problems when you are learning the ropes as it were is that we are all inclined to look for the "perfect" answer for all situations. The reality is that modern replaceable tipped tooling if properly specified (tip material, edge radius, corner radius, rake angle etc) works extremely well in most conditions. There will however be times that HSS is more useful if not essential. Tips can also be more easily damaged than most new starters imagine. One of the "don't do things" is rotate the work backwards with the tip in contact, excellent way to chip the cutting edge.

One other comment for either tipped or HSS, keep a magnifying glass handy to have a proper look at the edge, you would be surprised how many tools look good but the edge is obviously crap when looked at properly. For HSS or carbide, I also keep a couple of the small diamond files handy to "wipe" the edge every so often, doesn't help with a chipped edge but can work wonders with a slightly worn edge. Obviously an appropriate stone will do the same thing. As you become more critical of the cut you will find that the edge straight of the grinder even with a fine wheel can be improved significantly. I'm talking finishing cut performance here; if you are rough cutting a ground edge will be OK.

One other thing you will find with most tips is that their performance varies through the life of the tip, when taking the first cuts the finish might be a little rough and will improve with a little use. As the tip ages then the cutting pressure will increase and on our light lathes that can provide some interesting effects. The trouble when giving advice is that these changes can take a long time depending on your use and materials, I have tips that needed changing after a couple of cuts and others that seem to go on for ever producing superb surface finish???

Garth as in life in general it is a blend of both theoretical and practical solutions that will provide the best answer when things are not quite right. The trick, which comes only with experience or expensive trial and error, is to know which one will work this time. I've found that practical experience quickly narrows the possible theoretical solutions and saves a lot of time that I can spend doing what I want to. The most important thing whilst learning is have fun, be safe and make lots of swarf.

Keith

I had assumed that the holders were very hard, but on testing one of mine with a small file I find that they are probably machineable with extreme caution. There two points however:

The lower lip of the tool holder is only 6mm and would be reduced to 5mm so one should be careful when tightening onto the tool shank that excessive force is not used. This is probably not a problem as long as you are not superman or someone who automatically puts a 12'' tube on the Allen wrench :-)

Should you want to try this test the bottom surface with a small file (Not your best) I have tried mine and think they be machinable. The easiest way would be to put the tool holder in the

4 jaw independent and face of the required 1mm.

Cheers Brian

holder in the

Brian, interesting, are they the "Dixon" type as the five holders I have from Chronos (and the other places for that matter) are very hard and I can't scratch them. If the ones they are selling now are a bit softer a couple would be useful to me.

Keith

Keith, As it was the middle of the night (2.00am) when replied to Garth I just ran a very old needle file on the edge under the tool slot and it was not GLASS hard but very very tough and would certainly test some more before I attempted to do any machining of it. I am sure mine is same as yours since it is a Chronos Dixon clone. I have just test all of mine - all 13! and although the file can be made to just bight on the corner I am more convenience that the would be a pig to machine (if indeed possible), they are however 1 level less than glass hard which is reasonable as if they were glass hard the tool would slip around. In old terminology I would put then at Dark Brown rather than Blued. Blue is of course machinable as horologists do it all the time.

Cheers Brian

Just thinking about this (bit late but anyway)...I am correct i

thinking that collets are a good mounting for millers aren't I? Jus re-reading a model engineering book and they say that a theaded shan is best (either using a draw bar or otherwise) in order to stop th tool from being drawn into the work.

Is there a better way of mounting millers or are collets indeed th best way?

Cheers,

Garth

-- DR_

----------------------------------------------------------------------- DR_G's Profile:

this thread:

your best) I

tool holder in

just bight on

Brian, thanks I'll have a better look at mine before I invest in more to chop about. Not sure if the mill or the four jaw would give me the best chance of hogging a bit off. Perhaps I'll thow it up in a four jaw and risk a tip to see what happens. At least that way I will only have one tip to replace. :-) Not confident though with hard material, interupted cut and replaceable tip - think I've been there before :-)) Perhaps the mill with a solid carbide with very small cuts?? Thanks again, I'll let you know if I get any success.

Keith

On 28 Oct, 17:13, DR_G wrote:

Garth, in engineering most things are possible. You can use a variety of methods to hold milling cutters in a lathe and most will work with care and "light" use (very little heavy use is possible milling in the lathe anyway. You can hold the cutters in the three jaw and many have done so successfully for years. The problems are the three jaw is not particularly concentric or repeatable and so the cutter will not run entirely true. This makes for vibration, inaccuracy and cutter wear as the tooth loading will vary on the cutter. The cutter is also prone to slip if the cut is too heavy. Worn three jaws are certainly not the best way but can be made to work. Similarly if you have time to set it up all the time a four jaw can be pressed into use as well and will grip the cutter more firmly than the three jaw. Another "cheap" way is to buy a soft 2MT blank arbor (couple of pounds) with a draw bar thread and drill, ream for your chosen milling cutter. Cross drill and tap and secure the cutter with a grub screw from the side. Grind a flat on the cutter shank for the screw to grab on. Make up a draw bar and secure into the spindle. In my early days I made a few of these and they worked fine if a bit limited in the cuts they would take. A 2MT milling chuck can be used but have the problem that they extend the cutter a good way out of the spindle nose and with 2MT fitting being fairly light can be seen to bend and move about when milling. Again although not ideal on a lightweight lathe these can be pressed into service for light milling and will work. A collet system is the best for milling cutters and either the ER system or a threaded type will be fine for milling in the lathe. While the grip of the ER system might be slightly less than with a threaded shank if they are correctly tightened they will outperform any milling slide on a Myford. The main advantage with the ER system is that they are flexible enough to be used for cutters, drills reamers etc of any size within their range - very useful. If you are taking huge cuts in tough materials with a powerful milling machine then occaisionally an ER collet might allow the cutter to pull out, or so I'm told. I have used the system for years now and worked it very hard - I haven't had one move yet. I do tighten them correctly with the appropriate spanner and keep them extremely clean. To be honest Garth, I've even seen others hold milling cutters in a drill chuck for very light cuts in aluminium, I personally wouldn't trust them of feel safe but needs must, as they say adn I have seen soem sloww milling done with nothing more. The great advantage with collets is that they will hold both cutters and work, the ER type have the added advantage of having a range so that drills etc can also easily be used. The threaded type won't do that and the MT type will only take sizes that are almost exact for each collet, even a little undersize and the grip is almost non existant. So there are different ways, there are cheaper ways but in my opinion there are no better ways of holding a milling cutter in a lathe than a collet. Others opinions may differ as they say.

Have a look here for others experience with milling in the lathe:

Regards

Keith

Keith,

O.K. Thaks for that - confirms what I thought. I am quite taken wit the

"Shobha Collet Chuck with 15 Vertex ER25 Collets, £106.38 fro Chronos", although someone here said that they had a problem with thi type of system, and recommended a faceplate type collet mount.

Am I correct in thinking that the above Shobha type would give stiffer mounting solution, since the tool would be mounted nearer t the mainshaft bearings? The faceplate system seems quite bulky, an would appear to place the tool at a considerable distance from th mainshaft bearings.

Any comments?

Also, I could do with a full set of drills, but can't afford a 'name set. Does anyone have recommendations from any of the usual suppliers Ti coating? Polished? which are the best compromise?

Thanks a lot,

Garth

-- DR_

----------------------------------------------------------------------- DR_G's Profile:

this thread:

Keith,

Of course, you are correct. On closer inspection I don't have much t play with on bottom flange depth. I will re-check how much I would nee to remove to get a 10mm tool to fit. If it is around 0.5mm then I woul do it, any more and I will stick to smaller tools.

Thanks,

Garth

-- DR_

----------------------------------------------------------------------- DR_G's Profile:

this thread:

In article , DR_G writes

I use mostly 10mm indexable tools* on my S00 Dickson set - original post

• 4 holders from Myford, the other holders from all over the place - and none of them make the holder bottom out on the post. One or two are a paper's thickness away, though, and I have to be careful to clean swarf and debris from underneath before fitting the holder. (A 3/4" decorator's paintbrush lives nearby for this.)

On the rare occasions I need to use a heavier tool (for example, when roughing large items) then a 1/2" + tool in a Gibraltar toolpost serves admirably, just takes a minute to replace the topslide with this behemoth.

*ISTR that one or two brazed tip tools did cause problems, but I don't use these any more.

If I did have problems, I wouldn't hesitate to remove a smidgeon from the tool itself. If you just cut away the part that is in the holder, and leave the rest full depth, with a shoulder hard against the toolholder, this should minimise the loss of stiffness.

David

In article , DR_G writes

Garth,

I started out with a "grey box" metric set from Millhill, they are pretty decent - was about 20 years ago, and they are mostly still usable (though quite a few need sharpening and the odd couple have been replaced through breakage) . A few years ago I got a genuine Dormer set, they are noticeably better quality, but I can't say the holes are noticeably better (maybe in part because I usually drill undersize and open out). This year I treated myself to a Dormer TiN coated set, but they don't seem to me to offer much over the normal Dormer set, maybe because I am not subjecting them to heavy production use. I probably haven't given them a fair test yet.

I bought a giant-size bargain fraction + number set from Arc Euro a few months ago, the drills are OK-ish imports but the box is decidedly poor.

If you shop around, the branded sets are often available at fairly decent prices, especially at shows. My own view is that they last longer and are worth it in the long run, but YMMV.

I have also got fractional and number size sets, but quite frankly the metric sets (1.0-6.0 x 0.1mm and 6.0 - 10.0 x 0.1mm) are much the most useful, even when working in imperial dimensions (since you would normally be reaming any hole of critical size anyway). The 1/2" set does get used, but mostly only because it has some bigger drills in it. I suppose if I made loco injectors, the number set would get more use....

I am however a great believer in stub drills, especially if there is the slightest chance of the drill wandering. These are harder to find and rarely available in sets; Millhill do sell a reasonable range of individual sizes though. A handful of long series drills will get used once in a blue moon, but when you need 'em, you gotta have 'em; the set sold by Tracy Tools, though a bit of a mongrel collection of different makes, has covered my needs for years.

David

Garth,

There is not much difference in the overhang between a backplate mounted holder and a nose mounting holder. To all intents and purposes, they are the same. I could go out to the workshop and measure it to a fraction of a mil ;-)

Regarding the problems with runout on the nose mounted holders, the problems occurred with the 'British Made' ER25 holder still featured in the Chronos catalogue, and also the Arrand version. The Shobha version wasn't around at the time and could be better. At the cheaper price, it might be worth a try.

Jim.

My first lathe was a 10 inch swing Taiwanese job, which turned out to be a good choice. It weighed around 300 kg with stand. I was floundering with grinding HSS bits, and like you thought that "perfect" carbide tools would be a godsend. I was disappointed in that I seemed to be having even more trouble with these, damaging the cutting edges very quickly. Clearly these needed particular treatment, and I think are happier with a really big lathe - more solid, less vibration. And, there are several grades of carbide, adding to cost and possible confusion. After learning how to do a reasonable job of grinding HSS properly, it was a relief to get back to economical machining. It's not so hard to get to the point where you can make a reliable cutting edge. It took one night's lesson with a metalwork teacher, who showed the class how to do it all offhand on a bench grinder, to get the hang of it. He provided gauges to check angles, which are different for different materials to be cut. An adjustable angle gauge would do. Final lapping with a stone gets a satisfyingly keen edge. I'd encourage you to invest some time in learning to grind HSS bits. It might be a blessing in disguise.