You will all no doubt not be at all surprised that I haven't ye started on a 'proper' machining project (been busy recently wit parenthood for the first time). I have read the Tubal Cain steam engin books supplied by a kind forum contribnutor as well as several othe books suggested by forum members. I am still buying bits and pieces fo my ML7. Somewhere in one of my initial threads on assessing the ML7 someone recommended a type of collet for the ML7. I think it might hav been 'ER'. Could anyone explain the different types, and how the variou holders work? I would like to try some milling and want to use th collets for holding the mill tools. I've seen the morse taper type which are faily self explanatory. Is it possible to get a collet whic uses the headstock morse taper itself for compression, needing just nut screwed onto the mainshaft thread? I am guessing that the les attachments to the mainshaft the more accurate the collet. Should I bu metric or imperial sizes? I am obviously on a budget, so which of th usual suppliers would you reccommend?
I managed to get hold of a Sandvik insert type tool holder (8mm square and a set of inserts from a contact at work. Initial thoughs are that i is far superior to the steel ones I have tried in the past. I am tryin to get a few more to try. Question: can I use 10mm square tools in th ML7? I am using an RDG quick change tool holder, and even with th adjuster fully 'in' it seems marginal on height alignment. Maybe if ground the tool holder base down that would give some adjustment?
Myford's own collet system uses the headstock MT2 taper, with the collets pushed in with a threaded holder on the spindle nose. Each collet only holds one size. The ER collets have their own tapered housing, which is mounted to the lathe's threaded nose. Each can hold a small range of sizes, and can handle metric/imperial with one set. Don't totally give up on HSS tooling in favour of carbide inserts. HSS performs very well and is more flexible. You can lower the cutting edge by grinding it down for example.
I have 3 "Glanz" indexable insert tools 10mm and a quick change tool holder, all from Chronos and found I had to mill off 1mm from the bottom of the tools to enable setting to height. Since the quick changer is almost certainly identical to the RDG one I suggest you do the same. The annoying thing is that with the full 10mm one could almost, but not quite get it to centre height! The shanks of the tools are heat treated but are soft enough to machine with modest speeds and not too deep a cut. I have a small Sherline mill and if I recall correctly I took 4 passes to remove the 1mm.
Garth Hi, hope you enjoy "parenthood" you will find it hard work (understatement), expensive (significant understatement) and frustrating at times but ultimately nothing is more rewarding and enjoyable. I speak as a parent of two who at 23 and 21 are still costing me a small fortune. However, I can't tell you how much my day improves when they arrive on the doorstep.
Your collet question is a big subject and I'm sorry to say that I haven't time to do it full justice for you at the moment. A search of this group on "collet" or "ER collet" will provide a LOT of reading and the research will be worthwhile.
The Morse collet fits as you suggest in the spindle taper and can be closed in one of two ways, firstly Myford used to do collet closer that fitted onto the front of the spindle and closed the collet from the front. This was very expensive and seems to have been discontinued if you read their collet section of their on line catalogue. Secondly, other 2 MT collets (ArcEuroTrade, RDG, and Axminster to name a few) have a draw bar thread and close with a bar through the spindle. Obviously you have to buy/make a drawbar and nut. While MT collets have the advantage of fitting directly into the spindle taper they obviously rely on the spindle being in good condition to be accurate. Something that can't always be guaranteed on older Myfords. They only accept one specific collet size and therefore a full set of metric/ imperial can be very expensive. The draw bar type are not "through collets" so can only be used for short work pieces, but that would not be a problem if you are only going to hold milling cutters with them. Personally I wouldn't recommend buying a system with a view to just hold cutters as collets are a major advantage to work holding with a lathe. They offer much better accuracy and repeatability than a three jaw chuck and are much quicker to use than a four jaw.
The ER system has a major advantage that each collet will hold a 1mm range of sizes so you need fewer collets to cover the entire range of both imperial and metric sizes. A set of 18 ER32 collets will hold everything from 2mm to 20mm and all imperial sizes within that range. The ER system will not fit directly into the spindle of a Myford and therefore needs some form of additional collet chuck. These come in several types for the lathe, firstly a screwed body version that screws directly onto the spindle nose and close with a front nut. Fairly expensive and if not accurately machined (and I have heard of a couple of problems here) will not provide the necessary accuracy. The second type is a backplate mounted version (again ArcEuro etc do them) which is fitted to a Myford backplate. While this would seem to have the disadvantage of more interfaces therefore less accuracy, in fact the additional interfaces allow us the opportunity to correct things if they are slightly out by machining the mounting faces on the actual lathe it is to be used on. My own backplate mounted ER32 system once set up shows no visible run out on a 0.0001" indicator so it is working within a couple of tenths. These are again front closing with a nut so if your backplate has a hole through it they can within the limits of the spindle hole be used as through collets. One issue for some people with these is that they protrude out from the front of the spindle nose about as far as a three jaw; I don't find this a problem at all particularly as most old Myford beds are worn at the very front anyway.
Please accept my apologies for the rushed response but I hope it gives you a little to base your research on. I find my ER system excellent and it is in almost daily use.
If you use any of the QCTPs for the Myford you will have to machine about 1mm from the bottom of 10mm tools to get on centre height. I have done this easily with my small RF25 mill and it could be easily done with a Myford set up for milling. Take small cuts and if possible use a carbide cutter. The tools are not really that hard. I've done lots and they do provide better rigidity than the smaller 8mm holders. Don't abandon HSS altogether as you will find it useful in lots of situations.
"...and found I had to mill off 1mm from the bottom of the tools t
enable setting to height. Since the quick changer is almost certainly identical to the RDG one I suggest you d the same. The annoying thing is that with the full 10mm one could almost, but not quite get it t centre height!..."
Brian,
Wouldn't it be better to mill 1mm or so off the base of each too holder - that is what I'm thinking of doing?
To add to what Keith has said on collets, watch out for the nose mounted ER collet holders. One or two of us have had mixed results with holders supplied by Chronos and Arrand. If you dig back in the Google archive of this group over the past two or three years you should find threads on the problems. I finished up using a backplate mounting holder from Warco - like Keith - and that has given me acceptable accuracy at a cheaper cost than the nose mounted holders, and with just about the same overhang.
The Myford 2MT collets are the neatest solution, but the cost of the collets is high and the accuracy could be better.
I'd also endorse the backplate mounted ER chuck approach - I have an ER 25 chuck on my Myford and my X3 mill, and have just fitted a matching chuck on my Peatol (Arc do a very nice 60mm diam backplate mounded chuck which is great for these small lathes). The great advantage over the MT2 collets is (as mentioned by others) the ~1mm gripping range - a full set of Metric collets covers all diameters that you might want to grip in the chuck. ER25 gives you up to 16mm diam - you might want to go for the ER32 which goes up to 20mm diam, but on the other hand, an ER25 chuck and a full set of collets is cheaper and in any case it will take as large a diameter as the spindle bore on the ML7. If you want a simple solution (no backplate machining) then a MT2 ER chuck could be the way to go, but the disadvantage is that you don't have the through bore capability.
I previously had the Myford lever operated collet chuck with a full set of Imperial collets - great for holding Imperial sized stock, but crap for holding anything that is more than a gnat's bollock smaller than the nominal collet size. I believe the same is true of the MT collets, so even if you manage to find some, I suspect that you won't find them nearly as versatile as going the ER route.
I would strongly advise against an MT2 mounted collet chuck if milling cutters are to be held in it.
I bought one of the MT2 mounted Vertex Pozilock chucks from Chronos for holding milling cutters. I soon found that the MT2 fitting combined with the overhang of the chuck, results in a combination that can be _seen_ to bend even with a 1/2" cutter.
I solved the problem by turning up a body to screw directly on the ML7 mandrel. this is about 10X stiffer and is actually usable.
The only problem I've found with the ER type of collet is that the material you are gripping must be at least as long as the collet body or you won't get a good grip. Whereas with the more basic type of collet, you can grip short stumps of material.
--FWIW I've still got one and I *love* it. The trouble is it's hard to get collets 'across the pond' and if I need a special one in a hurry I'm outta luck. The thing I like about the MA99E collets is that they can hold short parts easily. I had to make a depth stop but that was easy enough..
I did the same as Mark, bought a lump of leaded, free-cutting mild steel and made myself a body to screw directly on to the spindle nose of my M42-threaded Myford. Then turned the end to accept ER 20 collets. A nice little exercise for you perhaps?
--
Chris Edwards (in deepest Dorset) "....there *must* be an easier way!"
The item to be attacked is the shank of tool - the bit that has the carbide tip fixed onto it with a nasty little Torx screw. The shank size is normally width 10mm x height 10mm after modification width 10mm x height 9mm - all the metal being removed from the bottom face thus lowering the tip without playing around with the tip seating which is very accurate to support the tip.
Where I went wrong in my explanation was to mention the word "indexable" which you not unsurprisingly thought referred to the QCT (Quick Change Toolpost). In fact the carbide tips are referred to a "indexable" tips since in industrial use a damaged or worn tip can be replaced without resetting the machine since they are made to very close tolerances and the seating and fixing mechanism (often a tapered screw) are designed to ensure very accurate and repeatable positioning of tip.
To repeat! Do not touch any part of Quick Change Toolpost or its Holders!
Take your Sandvic tool and remove 1mm from the bottom face of the shank. Test the hardness of the shank first it will normally not be too hard to prevent cautious milling
Hello Garth, A couple of comments slightly tangential to your post. You say you've not started a 'real' project yet..... You should! I am as guilty as anyone for buying toys, but you really don't _need_ collets to have a lot of fun and satisfaction from your machine. I have built steam engines, model IC engines, parts for vintage motorcycles and cars and only within the last year acquired some collets and then only because they 'came my way'.
Similar comments apply to the carbide insert tools. HSS ones are perfectly servicable and do offer some advantages in that they can be re-sharpened and/or ground to a 'custom' shape for some particular job. Indeed, occasionally for some particular jobs even old carbon steel tools can be a benefit. Carbide tools are a major benefit for manufacturing as they can be used at high speeds and feeds on nasty materials in a CNC production machine, but you're unlikely to use those materials and can't get the speeds and feeds from your Myford.
Start using the machine in earnest (not anger ) and you'll get to find what it is that you want to suit you own taste.
I know that is the received wisdom, but in practice, I have found indexable carbide tools to be perfectly usable on my Myford on "normal" materials - in fact I started using them when the only lathe I had was a Peatol/Taig. As long as you keep to good quality inserts with small tip radii they cut very nicely in my experience, even at the relatively low speeds achievable on hobby lathes. The only problem I have had with indexable tooling was with an el cheapo set of dubious imported origin, where the holders were not accurately machined, the inserts were useless, and the torx screws appeared to have been made from soft cheese.
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