Member postings for Neil Lickfold

A work mate once told me, the real competition , is not how fast you work, or how accurate you work, as with out those two, no one will employ you. The real competition is working and not getting dirty, Keep a rag handy to regularly wipe your hands and some paper towels handy to wipe down the machine tool handles etc. Then only use cold water for the hand washing. I always have clean hands apart from repairing old grungy things.

I have found that cutting steel with aluminium inserts works really well on the home hobby lathe. Mainly because the hobby lathe does not have the power or rigidity of a commercial industrial lathe, although most do still have the rpm range. The Al inserts on steel will still outlast a HSS tool and run a higher surface speed. I have also found that the smaller nose radius has a lower power requirement also. Another approach is to rough out using a grooving tool can also be really effective on smaller low power lathes. Like a 2mm wide insert with a 0.2mm corner radius or even a 0.4mm corner radius. There are MDT(Multi Direction Turning) inserts for some of the grooving series tools.These tools allow you to plunge and turn left hand or right hand, with a 1mm radius insert. Also is very effective when turning an area that is relieved, like what you are turning in the photo. Turning with a left hand and a right hand turning tools also work. Like using DCMT style inserts or the DNMG style inserts, are 55 deg included angle inserts. I use DCMT11T3xx , mainly because of the huge range of geometries that are available, and industry standard inserts are often cheaper than the smaller hobby based sized inserts. I have a selection of inserts in my album. Chip control is the real key to any turning, and finding the depth of cut and feed rate to make little chips instead of long strings of swarf is equally important. With grooving, this is easily achieved with the 1/4 or 1/2 turn of the cross slide for example, or the pecking style of Z axis feed when turning along towards or away from the chuck. Seldom have I found a negative steel insert for industry to be suitable on smaller lathes. The ones that are effective for me have been the cermit sharp finishing inserts, but I now rarely use them.

My ZX45 has the split nut and it is not really all that good. It can not be set to a low level of backlash like 0.05mm for example and hold that level for any length of time. Already after about 15 hrs of use, the backlash has extended to 0.2mm . I just can't be bothered to keep chasing it. With ball screws the real important part is keeping the seals in good order, so making sure that chips/swarf/dirt etc stay away. Making or coming up with a way to keep it dust free makes a huge difference to the life of the assembly, apart from the regular correct oil feed as well. Just need to find a way to do that on the ZX45 mill, especially on the X axis. There is also hybrid ballscrews that use precision ceramic balls, but they are way outside the scope of the home workshop. Preloading a pair of nuts with some form of spring system works well, and there are many options for this.

Why not place the vice so that Y axis is in line with the jaws? IE rotate it 90 deg.

Neil

The new Kurt with the sliding jaw stop and other jaw offerings make it look like a really nice to have vice Talk with who you brought the vice off, and see what they have.

Neil

When dialing in a vice, look down the table, and eye it close to the run of a T slot. Then just lightly nip up one of the hold down screws/bolt, at the end of the 1st dti setting. Travel along, and then move that end, a little more than the distance shown. Lightly tighten that end, go to the 1st end, loosen nut/bolt and move to the full distance to zero. Another quick way is to have one end with a dowel tenon that is a fairly close fit to the table T slot. Then it is just pivoting on one end. Another solution that was revealed to me recently from a farming friend, was he made some special T long T nuts. These are about 40mm long or so( just fit in the end of the table slot, and the top of the T nut protrudes the height of table by 3mm or so. Less than the tenon depth of the slot in the vice and rotary table.The T nut is split longitudinal to about 3mm above cutting through. Drill tap in the centre with what ever sized centre drill that is bigger than the diameter of the screw being used, ie M6 use a 7/16 centre drill. Then turn a 30 deg taper on the head of the screw to open and hold this T nut in place. Then just above the table , mill the side of the raised tenon parallel to the run of the table. Then place the vice or what ever, against the milled edge as the reference.

In my case where the run of teh T nut slot is not true to the run of the table, it is a great fix with and expanding T nut.

Neil

Andrew, you will be after the double nut type if you want a preloaded zero backlash ball screw. These days the rolled thread ball screws from Germany are just as accurate as the ground ones. There is also varying degree of the amount of preload as well.

Neil

An interesting topic for me. I have been using an old Kondia mill, that has ball screws for the X and Y. Just a wonderful old machine. The best part is the zero backlash, and the ability to climb mill. So my next upgrade to my ZX45 mill will be to get or find a set of ball screws for it. Then I can also climb mill etc. Later down the track if I decide on power feed etc can fit some stepper motors for that as well. Although it does have the bolt up nut to reduce the backlash in the threads, I'm not convinced it will be any good really, compared to the zero backlash ball screws.

If you are going to do any rebuild, I would recommend trying to find a set of ball screws to give the anti backlash. They are a little bit of work to fit at times as well.

Neil

Turn a test piece, with a very fine feed rate. Then place your DTI on that turned surface and try to asses the roundness of the test piece in place on the spindle. Then cut that piece off the bar, and then place that into a vee block , and again check for roundness. It also depends on the type of the DTI being used, and the rigidity of the stand/ DTI holder as well. Then decide if the roundness of the part is acceptable for what you are trying to achieve.

Neil

I am making a sub plate for my vice and rotary table etc. For the Vice, it will have some dowel positions so I can quickly have it parallel or set to 15, 30,45 deg. As I have a ZX45 mill, the plate will allow the holding things like teh vice and rotary table to be further forward on the table, so the cross slide is always in full contact area on the machine. If I have the vice mounted on the middle T slot, the edge of the back jaw centre line means that the cross slide is no longer on the full engagement. I guess it is an idiosyncrasy of my mill. I also have the vice and rotary table switched compared to how you have yours, mainly due the restriction of the vice to the rotary table handle. This is another reason for making sub plates. The I can quickly add or remove and accessory that for most things will be accurate enough. Yes I will have to re cut the edge of the T slot , as they do not run true to the run of the table, about 0.1mm over the run of the table movement. The down side the 14mm tennon slot won't be 14mm anymore. How ever , having the reference dowels always on the same direction against the trimmed edges will be more beneficial to me. The other option is to rework the whole table.

Neil

Lh or Rh end of the table all depends of the handed direction of the other accessories you are wanting to use. Re the table T slot and the alignment of the vice or what ever with a dowel, it should easily be with in 0.01mm per 150mm. If not, maybe the T slot that is your reference needs to be re cut again so that the edge of the T slot is true to the run of the table.

Neil

If it were me, I would not get the higher RPM motor, but would prefer to get the lower 1400 or so rpm motor. With the VFD the 1400 rpm motor can be over driven to 2800 rpm or so. But as the RPM increase so does the power needed to spin at that rpm range. But the 1400 rpm motor has a bunch of torque. But at partial RPM it is not so good. The only issue is at slow RPM's. Some motors do not like running below 15 hz for any length of time, as they can over heat. Although you can get to like 4 to 5 hz, based on a 3k motor, that;'s like 300 rpm. For me I use the 200-300 rpm for tapping etc and it really does need torque to tap successfully. But the 1400 rpm motor would be in the 10 z range.

As others have mentioned, the total power can be limited on the vfd to the motor, same as peak current draw. A 2 kw motor can emulate that of a 1kw motor.

A friend of mine was always asking how i was getting better surface finishes yet I was not running anywhere near the rpm he was. It was sharp tools. A sharp tool at 600 rpm will give a better finish than 1600 rpm with not so sharp tool.

Neil

On my Myford super 7 , the spindle runs to better than 0.001mm truely amazing. It was new in 1972, still has the original shaft and taper bronze bearing, and has been very well looked after over all. It was re fitted and I did lap the spindle back to being round again, and then fitted the taper bush to the spindle. But before I reworked the spindle, it had done more than 100,000 parts in a production environment that I know of, and who knows how many parts it made when used as a production small parts lathe before that. The roundness was about 0.002mm which is still way better than most Eastern machine tools today, except for their Tool range of lathes that do have better bearings. Most I have looked at recently only have a spindle that is about 0.006mm to 0.010mm of roundness. Depending on what you want to make will determine the roundness you require. For the competition model engine pistons that I trim on my S7, they perform better than the ones supplied by the factory who makes the engines. If I trim them on a lathe at work that has only a roundness of 0.002mm, they do not run anywhere near as well. If you can get a Myford second hand like one recently that came up on a thread with lots of accessories, I am sure they will be happy that it is going to a home where is will be used and appreciated. Yes they maybe a little more up front, but no one complains about a quality product or the really good surface finish that is achievable .

Neil

A 4 flute endmill is not good practice when cutting a slot. In general there is too much swarf to cope with when there are 4 flutes or more. 3 flutes or less is better for slot cutting. If you take lots of small cuts , so in the region of 1 to 1.5mm deep the 4 flute will cut a slot. But in general a slot drill cutter will take about 50% of it's diameter as a depth of cut, like cutting a key way . I never bother with the wavy sided roughing cutters. For a 12mm slot, I would use a 10mm 3 flute end mill/Uni Mill cutter, and then go down it with a nice 12mm cutter. If the size of the slot is important, then using a new or very good condition 10mm cutter , 4 flute or 6 flute and finish the sides of the slot that way with a 1.0X cut off the centre line each way until it is at size. Most carbide cutters are about 0.02 to 0.03mm in diameter undersized anyway.

With tool steels, or steels harder than free machine MS, often the depth of cut is about 1/2 and the feedrate is about 20% less with a surface cutting speed also about 20% less maybe more depending on the steel and the sturdyness of the mill and set up.

Neil

This is correct. I can't find the reference for when I made some MT2 and MT4 tapers recently, but the spec was given as a diameter at one end, and a diameter at the other end, and the length of the distance apart of these 2 dimensions. The part that I found was interesting was the tolerance specified on the taper. The outside part could be made to the same taper, with the small end, could be made smaller by 0.0001 inches. The inside taper on the small end could be made bigger by 0.0001 inches. This difference would make then jam/wedge tight together. There was also mention to the reason for the sleeve extension outside of the sleeve, as an area to yield when the smaller sleeve is inserted and drifted to position.

Neil

I was looking into this recently.

Found this note interesting.

A question often asked within the clinical community is, “what specifically is a Morse taper and can it provide a stable connection between components?” A Morse taper is defined by the angle that the taper surfaces make relative to the longitudinal axis of the component and by the mismatch angle between the male and female part. The original Morse taper angle defined by Stephen Morse for tools was a relatively small angle of 2° 50′, with the mathematical relation that tang 2° 50 = 5 %.

Neil

The ultimate cnc still does not exist yet, but they are slowly getting there. Be it a manual machine or a cnc machine tool, to make very precise parts, still requires a high level of skill either way and the ability to be able to measure what you are making. Now there is 3d printing of metal parts from what look like regular plastic 3d printers, they those parts are sintered . cnc is just another tool technology to make things with and have fun doing so at the same time.

Neil

Google shows A set for sale with collets and adaptor for sale. http://www.myford-lathes.com/accessories2.html

Maybe it should be bonded with XXX glue/adhesive/bearing retaining compound/thread locker/ etc

Neil

Its the angle of the photo and the lens making an illusion. They are MT4 taper.

I used these inserts, picure in my album and on the recent insert thread. TNGG160402R-S PR1125 (Wonder Insert) One hard steel Iuse it at 25 to 30 M/min surface speed,slow feed like 2 thou per rev or so. For the Drill chuck, I put a 10mm dowel in the chuck, and did the chuck up tight with the C spanner that comes with them, normally for undoing the chucks. Anyway I held onto the dowel, and used the centre to support it. Then just nibbled away at them at about 200 rpm and taking about 0.4mm cuts(0.8mm diameter) till I got down to about 17mm diameter. Then used a hacksaw to cut off the excess, and cleaned up the end face with small cuts. Then re tapped the M16 deeper. The other holders we held in the reverse jaws. They were hardish on the outside, but soft under the 3mm or so skin thickness. Once through the hard skin, could up the rpm a bit. I should not have had the parallel part where the M16 thread is, I should have just round off the end. The Drill arbour did have already the M16 thread in it. It was not a tanged MT4.