Member postings for Neil Lickfold

This is what a made up to enable an extend DTI down a hole to indicate it concentric to the front. As pictured, it was set on the front, as a check for it's effectiveness. It was within 0.02mm of the indicator being on the front of the hole directly. Then it was travelled down the bore to see what the run out was 220mm down the hole. In this case, the bottom of the hole was then zeroed, as well as the front of the hole zeroed. Then the out side turned concentric to these values and a new datum being established to then make the part as concentric as possible to the inner hole. In this case the correction was 0.1mm on the DTI.

Neil

The spring wire is a good idea, then one thing less to be remembering.

Just noting the amount you have to turn the dial back is usually good enough. I have seen where people have a spring on the cross slide to keep it in tension towards the feed screw handle. I have also seen where people have put small pneumatic cylinder to act like a spring as well on the X axis with a near constant pressure reservoir attached. ( a bike tyre tube ).

Neil

In my experience, a new or a chuck in good condition, only requires tightening on any one position. Older chucks that are near f---ed need to be done up on the other hole settings as the ring just flops around and does not tighten properly. I have seen on old chucks where you use 2 keys at the same time gives great repeat ability. In reality, if the chuck is like that, throw it away and buy a new one. Some people like wasting time and think they are saving money in the process.

All the book data is based usually on flood coolant and an insert edge life of 15 to 25 mins. Of course a production machine is going to be taking away a lot of chips at that rate. Stainless is often quite a high feed rate. There are stainless specific inserts to by with special coating and a cutting geometry to make it chip. On a home machine, I by the finishing inserts and don't run my spindle any more that the fastest position on the low speed main pulley. I no longer use the high speed main pulley. I went with the DCMT11T3 series of inserts and holder, due to the large availability of different inserts, and because the company I mainly buy from for home, does sell in small insert quantities. The depth of cut and feed rate is machine and material dependent. So take cuts deep enough that you can get good chipping and a feed rate that makes it chip. I would think that if you had a insert with a 0.2mm radius and a DOC of 0.5mm with a good coolant, will be able cut at 0.1mm per rev no trouble maybe higher. With stainless and Ti material, the coolants for those materials , have high pressure additives that aid in the sharing and deformation of the material. On small lathes, the larger radius inserts seem to load up the machine more, so my common radius choices are 0.2mm for steel and 0.4mm for Ali. I would use about 300 to 400 rpm with coolant.

Neil

For tool holders, there are screw type, ie hole in the middle of the insert. These same inserts generally also have various top clamp options. Some use the same hole insert, but have a centre pin that pivots in such a way that it retains the insert, while others may have a wedge design that then pushes the insert to a centre pin to hold it. There is also the top clamp that does not require a centre hole, and some holders will take both inserts of the same geometry, but with or without the centre hole. Where possible, I try and buy the top clamp style holders that take the common inserts with a centre hole. An outer turning tool insert can then be used in a boring bar if it takes that geometry insert, (usually a N neutral geometry insert) and the boring bars, especially the smaller ones under Ø20mm have a centre screw for the inserts anyway. Some brands will go down to 8mm shanks for the outer turning tools, but most are the 3/8(9.5mm) or the 10mm shank tools. Some tools like the TNMG16 holders often start at a 12mm shank, so need thinning on the bottom side to bring the insert to the holders centre line height, in my case 9.5 mm for my Myford S7. The smaller CCMT 06 inserts, are available in 8mm shanks. I try and stay with common industry standard insert sizes and get my holders to match best as possible, and only thin if I have too. You can tell the common industry standard by getting a book from a company that sells locally. The common ones have loads of geometry styles as well as material grades and coatings. The less common only have a few geometry styles , and often only offer the inserts in a few grades , sometimes with no other coating options. I learnt long ago that a cheap insert is not always cheap in the longer term. Most of the tooling company catalogues these days are a wealth of information, with optimised cutting conditions and what coatings etc can do what. If you do interrupted cutting, they have insert suggestions and grades for that as well.

The book is well worth having a look at to see what is happening.

Neil

Without seeing it in person, this looks like it is an ok thing. It has the 10mm thread for the draw bolt and a set of collets for a very reasonable price. If the collet chuck is good, to me it's worth buying just for the 2MTER16 chuck.Certainly beats having to make one. Sometimes making your own has benefits , like you know how good or bad it is right away. Hope this helps, Quite often I make stuff, mainly due to the long wait from overseas. If it is readily available and to the level of precision they claim, I buy locally when possible. I also make some of my own collets as well and other things for the ER series of tools. Neil 

http://www.rdgtools.co.uk/acatalog/ER16-COLLET-CHUCK--10-PIECE-COLLET-SET---2-MORSE-TAPER-SHANK-12568.html

Edited By Neil Lickfold on 16/01/2017 09:32:57

Ian, this is where I get my cutters from. https://www.carbidenz.co.nz/ I buy mainly 3 flute and 4 flute centre cutting. I buy the non coated Ali cutters for plastic, Non Ferrous, and woods . Coated for steels mainly. If you make your own MT2 with ER16, it can be made quite short, like about 35mm out from the spindle face, or shorter if you have some of the back end of the collet inside the spindle face, but then only leaves about a 3mm wall section.

The reason for suggesting ER16 is it will be the shortest collet system with a MT2 mandrel. Realistically you are not going to use bigger than 10mm cutters anyway.

In a small mill like that, cutting steel, realistically, it will be best to use cutters 8mm and smaller. I would look at a collet system like an ER16 up to 10.3mm collet, with the smaller compact castle nut series. The shorter the holder the more ridgid it will be and also allow  slightly more room between the table and cutter.  Small cutters ie 6 to 8 mm will chatter less and can run at higher rpm and in turn you can remove more material quicker.

Cutters 8 mm and smaller are also significantly cheaper than the 10mm and up cutters. I would recommend that what ever collet system you decide to buy, get the highest precision collets that they make, like in the Regofix series, I would buy their high precision ones RegoFix is the UP range. They run more concentric that the regular ones, you get longer cutter life, (very measurable) and improved surface finish for not much more initial out lay. In the Regofix series of collets, they go to larger diameters than the generic suppliers of t he ER collet series. For MT2, you can also get MT2 collets in the standard cutter sizes. The industry standard is 3mm shank for very small, also 4mm shank for the very small, then, 5mm,6mm,8mm, Some 7mm cutters are on a 7 shank, but most are on an 8mm shank. Some 5mm cutters are also on a 6mm shank. This is all for carbide cutters.

Out here in NZ, you can get carbide cutters at such reasonable prices,and very good quality for less than averge cost of HSS cutters. I have not brought any HSS milling cutters in the last 6 years at all. My last HSS cutter was a woodruff T slot cutter and a small dovetail cutter. Lots of choices.

There is advantaged to the ER system, and I would recommend buying the smallest ER system that you need rather than the bigger one that you will most likely not use. The smaller systems have shorter collets, which is really good for the smaller endmills.

Neil

Edited By Neil Lickfold on 13/01/2017 20:11:56

That's roughed to the centre line with a 80 grit diamond compound wheel along with the backing off taper and the relief diameter and general shape. Then the centre line split is finished with a 180 grit diamond compound and the same with the finishing of the tool shape. So it is done in several stages, a roughing and wheel change then a finishing. The finishing is only done on the centre line split near the outer edge, just visible, about 0.02mm is left for this op, and then only on the leading and trailing of the form. The nose radius is done by hand very carefully with a fine diamond EZ lap. These are a desic diamond lap and the finest/smoothest grit that is readily available. Just don't use much pressure when using the desic laps ,or else the stuff just strips off them. Like I said earlier, I only make tools that are not redilly available from a tool supplier. The front edge of this tool is just big enough to cut a 0.5mm pitch thread. It will not cut a 0.75mm pitch thread. This particular tool is made from a micro grain carbide where the main part of the original cutter broke off. i just use their scrap high end endmills etc to make these special tools from. This blank is from Kobelco in Japan, but believe that Mitsubishi carbide has purchased the company at some point. That was the name on the tool blank. I have a 6mm ground stock D bit split to the centre line that I use for setting the tool height to the correct centre line, before using this tool. Micro tools are a lot less forgiving so extra care is required when setting up with them.

I make my circlip groove tools is a similar manner, so are roughed out and then finished.

Neil

Sorry Michael, oh well no more shortening of names from now on.

How do I edit a post and correct spelling?

Mike G, The same applies to any turning tool that is rubbed from the reverse. It is worse on a inner sphere as described, you have the work piece acting as a lap over the cutting edge. The above refers to only a solid turned sphere. If there is a small hole or if the bottom of the sphere is formed some other way it is ok. The problem with any small tools is the very centre of any part. As it has zero surface speed, it can only be removed by deformation or by the chisel effect. Very small tools are just not that strong in their geometry and by their nature are weak. That makes them very susceptible to centre line height setting. Often when boring having the tool slightly above centre height is an advantage as the loading of the tool, then deflects down and in doing so reduces very slightly the cutting load. When the tool is exactly on centre line, when it deflects down, it will take a very slightly bigger cut. When it is set below centre line, it will have the tendency to be digging in and taking cuts big enough to either damage the tool, or leave a very poor surface finish. So with small tools, the more rigid the material the tool is and the lighter cuts makes for the tool lasting a long time with good surface finish. Cutting fluids that promote the shearing of the material, ie reduce cutting forces, help a lot as well. On small stuff, I keep the corner radius to less than 0.2mm or 8thou. On micro bars, less than Ø3mm diameter, I have the tool radius at 0.1mm or 4 thou. This allows at a 1 thou per rev feedrate to get accptable surface finishes. If I need a very good finish, I hand feed at about the 0.01mm per rate approx. So when the spindle is doing 600 rpm, I feed the main hand wheel so that I do 1/4 turn every 7 seconds, or 1 rev in 30 seconds. This is for the 0.1mm nose radius tool. With .2mm radius tool it is turning the hand wheel 1 rev per 15 seconds, or 4 revs per minute. The myford box does not allow 0.001 inches per rev feed rate. It takes time to learn to turn a handle at a feedrate, but is really worth while to learn.

Here is the micro threader, Great work there Danny.

I buy what I can as making things takes time. Not retired, I would rather just buy and use it. I only make special tools that are not available, like a threading tool to cut M5X 0.5 pitch thread that goes into a 45 deg cone, it is only 0.4 mm wide at the business end.

Neil

That's them Muzzer, I have them at work also, but in the larger sizes. The through coolant of commercial machines is nice, but at the same time, don't want to be showered in coolant at home. In the smaller sizes I like the CC style inserts, in the larger I like the DC style inserts and the TN style for roughing in the larger bars, ie the 32mm and 40mm shank bars.For Home I have the small ss inserts, the TNMG16 as a std oiuter turn tool, and the DCMT11T3 inserts for outer turning as well. For jobs where the work piece is like a bell and sings, then I like to use in those cases the tools with the active vibration dampening, ie the ones with a floating weight. Regular steel bodied tools can be dampened by drilling a hole and fitting a loose piece of carbide in the hole. So a 5mm hoe is about right for a piece of Ø3/16 carbide piece. The carbide slug wants to be big enough that when it vibrates it makes the bar sound dead instead of ringing. For boring bars, I make the hole no more than 50% of the area of the boring bar, and plug it with a brass plug. This can also be done to external tools as well, and is good when you have tools sticking out a long way, and a work piece that is likely to be vibrating itself. Work piece harmonics and cutting tool harmonics is an interesting subject all on it's own. Neil

The Dimple bars work great. I have a few and think they are great. I use these inserts in the ones I have. CCGT060202MP-CK PR1425 These inserts are by Kyocera but fit the Dimple bar really well. I have the 10mm shank dimple bar , and the 8mm shank bar, that both take 6mm series insert. These have a small 0.2mm nose radius and are very positive and sharp cutting geometry. Will cut all material, even ball bearing race ways. I also brought an external holder to use these same inserts for OD turning.

The only other option I think for boring bars are the vibration dampened bars from people like Sumitomo Corp, and others. They have a Carbide weight that floats around near the head of the boring bar, and cancels out a lot of the vibration, but they are quite pricey. The moving weight type are also made by Kennametal ,and Sandvik, or used to be anyway.

Neil

On 2MT I would go with the smaller ER25, as I assume you are going to use it for holding cutters and not a work piece. #2MT drilled out will only allow about a 13mm through hole if being used in a lathe spindle .The #2MT is shorter than the ER32, and being a smaller machine the short moment is more rigid.

For a lathe, and assuming you have made an adapter, it wont make any difference if you go to ER25 or ER32, as you won't get much more than about 15mm stock through that spindle, although some lathes do have the shorter #2MT and a 16mm spindle bore.

RegoFix collets go to slightly larger than the other makers of the collets, like with ER40, most only go to 26mm, but RegoFix make them to 30mm.

For mine, I went ER40 as I made a spindle assembly that takes the ER40 collets and has a 31mm spindle bore for a specific purpose.

Neil

There is a hot process that takes place at about 140deg C, you can buy the stuff from heat treatment supply companies. It has caustic soda in it, and other salts. I consider it safe to use if you take the appropriate precautions.

They will also give you the instructions for it's proper use. It does not work on stainless steels or steels with a high chrome content. But us great for MS or heat treated A2 tool steel and P20 that I know of, does not effect a steels temper as the 140C is below the steels tempering range.

Neil

Got it sorted. I made up come collet blanks and made some step collets that I needed.

I made the rear bearing diameter 23.98mm, nice slide fit into the collet closer. The body of the collet, I made parallel and put a Ø0.3 mm relief 10mm up from the bottom for 8 mm long. This is where I drilled 4 holes for the slots to run into. I also put a small relief at the bottom of the 15 deg taper where it meets the body diameter .I used a 0.2mm radius tool for the finish turning of the parts, and made the relief to Ø23.5 mm .The front taper I made 15 deg per side. The intersect diameter of the 15 deg taper to the front shoulder I made it 29.0 mm and then turned it parallel to Ø28.3mm .The front spigot I made that Ø22.0 X4.0 mm long. I wanted the front of the collet very close to the retention nut. The standard ones look to be 5mm long on the spigot .After splitting the collets, just made a shallow tapered mandrel to stretch the collet open. I made them from 4340 steel and left them in the supplied condition of about 30Rc. 70 ton steel. PS If the collets are not spread they do not release forward. Also the spread only need to be just enough to allow the retention nut to hold the collet when being placed into and out of the collet chuck.

Neil Lickfold