Member postings for Neil Lickfold

It is very important for the cutter body, to have the full length of engagement in the collet itself. If the cutter is 3/4 of the way in the collet body, there is a high probability of it walking out on a big cut for sure . The thinner wall collets require the full length absolutely. It is for this reason that I have different collet sets, with the smaller series collets for holding the smaller cutters. Cutters with a 4mm shank or smaller I use the ER11 set. For 10mm to 5mm I use the ER16 set and for over 10mm use the ER32 set or ER40. Hanging onto a cutter with less than 1.5 diameters is never a good idea , so then you are better off buying a longer series cutter.

Using a pair of tools to tighten the collet nut is a zero torque arrangement and you can get a lot higher closing pressure instead of using just 1 tool and locking the spindle or 1 tool and a bench holder.

Neil

Buying precision collets saves a lot down the line. I suggest buying the highest precision collet you can afford at the time. Then buy more as you need them. Having cutters run better than .01mm every time is important and does make the cutters last longer. Also it means you have confidence is setting up a part and know it is concentric within the collets accuracy. I bought some AAA from China collets that are better than 0.005mm but not 0.002mm though.

Even though they seem expensive , precision collets really are time savers in the long run.

Neil

What I like best about the VFD and 3 phase motor on my myford is the use of a microswitch for the stop of the lathe when thread cutting. Especially when cutting internal stuff. I know some run it backwards and then feed out, but feeding in knowing that is is going to stop within 0.1mm every time is just great . I have breaking and soft start settings. I put a 3/4 kw motor on my myford about 1hp approx. I just wish I had done it many years earlier. It is smoother running and quieter over all. The smother running shows up in the improved surface finish of parts.

Not cheap , that is true, but well worth it in my view.

Neil

I really like the Hardinge top slide method. As it has a cam that retracts the tool on the flank angle.

The way I set it, is set the compound at 1/2 the thread angle. Have the lever in the forward position, and the compound wound to the forward stop position. Wind the cross slid to a touch, and then go in the full finished depth. Leave the cross slide at this position. Use the retract at the end of each cut. Wind back on the compound. Take all cuts using the compound slide only.

Without the retract lever, I do the same on my Myford, and do all the feeding to zero on the compound. For most threads, 1 turn on the compound is the max required amount of retraction required.

I have done the feed only on the cross slide method as well. But prefer the feed on the compound. Unlike the youtubers, my method does not require and trig to get the depth of cut. That is set from the cross slide , the same as if you were not incrementing the compound slide.

Neil

Get some of the same material you made them from. Create sticks of that same material, and then get it welded up with that material. Grind through the nitrided layer first for the area to be welded up. Then recut to correct profile and re nitride again. Welding with parent material is the best solution. Remove the nitrided area first, as the nitrided material is no longer the same as the original material, and it will crack trying to weld through the nitrided area.

Neil

Wire edm is the better process to make small tools from hss or carbide. Yes you can grind such a tool on your tool and cutter grinder. But asking how long it will take, is very difficult to answer. The grade of hss steel, the type of wheels you are intending to use, the type of cooling you are using etc etc. From 40 mins to several hours will be a ball park time figure. The other issue is the precision required of the tool dimensions as well.

Neil

Good industrial holders are expensive for many reasons, some because the retailer wants to tripple their margin, some because of the materials used, and increased difficulty in manufacturing, the heat treatment, the vibration dampening qualities, or other vibration control technology as well.

Then there is the through coolant range , where the coolant comes out near the cutting edges , like the new series of grooving and turning tool holders. These work well with coolant or chilled air for the dry cutting technology.

There is a fairly new material for tool holders so that the tool does not ring. No idea how it works or what it actually is. This is used in many of the shrink type milling holders, and some of the insert holders.

some examples

Swiss tools

**LINK**         

Mitsubishi part off tooling grooving          

**LINK**

Kyocera turning tool holders 

**LINK**

Edited By Neil Lickfold on 10/09/2019 20:29:50

I have an Emco 4 jaw self centering chuck that is a really good and has great repeatability as well. No idea if they are still made or their price now days.

Neil

One issue is that the collet is being supported by a Mt2 or MT3 shaft.

If the collet chuck was more solid, so like a plate that connected to the spindle with the collet int, would be more rigid. What you have is basically like turning a part at the end of a 60mm extension that is only 20 mm or so diameter.

Another separate issue is the bearings of the spindle itself and their influence as well..

So check the inside of the er chuck , and then see how little pressure is needed to move it 2um. It won't be as much as you might think. Next do the same but on the spndle directly, same again, the amount of pressure to move 2um. This time it should be considerably more. If it is about the same, there is something not quite right with the front bearing of the spindle.

Neil

Using a finger type DTI can help in setting the swash of the part on the side of the jaws if it has a flange to reference from. If it is a piece that has flat sides, then running an indicator up and down the length is the only way to check it is running true. You have to spend Serious money on a 4 jaw chuck that can hold flat stock true to the run of the chuck. Another option is to use sacrificial pads that are used to hold the part. Then it can be held and as you indicate the length, tap it true at the free end. It can take some time to set up some jobs and not that long with others. Having more than 1 indicator can be helpful, as well as 2 keys for the 4jaw chuck.

Neil

How viable are ceramic bearings for turbines these days ?

Neil

The grey on my Myford is no longer the same as the fixed steady which has been in a box in the dark for the last 20 years or more. I don't use it often. But the main paint of the lathe is either faded or oxidised or Both. If you have a sample piece like a cover or accessory, they can scan it these days and make a matching colour. New paints also have UV stabilisers in them, something that may not have been in the original paint.

Neil

The pin is only to ensure that the tools are placed in a repeatable radial position. Especially when they are made from bored in position collets. If your quill is near perfect, the pin wont make much difference.

I have used a Starret one for years and recently bought a ceramic one with a 10mm ceramic pad instead of the Starret 6mm pad. What I like about the ceramic, is it is un effected by parts that have become magnetic. The wigglers do work but are not as good as the Starret or the ceramic centre finders.

This can also happen when trying to part off dry without coolant or lubricant.

Parting through a thread never can work well. One way around this is to place a piece of studding in the hole, and part off through the studding till you get to the non threaded stock. Generally leaves an ok cut across the thread.

Or else tap the part as a secondary operation, so you are just parting off a washer effectively.

Neil

Well done Adrian. It looks good. If you make a gang set , you can always make another cap to suite that length.

Also you can make different caps, to suite different ID saws smaller than 1 inch, by adding an adaptor ring to either the cap, or into the main holder.

There is lots of advantages to making your own tooling. One being you know the accuracy of it, sometimes you learn another skill in the process as well. It is best to make the cap of a different material to the body, to reduce the chances of it galling or picking up.

Neil

Out here , the accessory insert as we call them, can be changed out at any time or replaced and swapped with what ever you want, as log as they make the modules to fit that form factor of outlet or switch. So you can have a USB charge point, or a sensor to turn on the power point or light , or it can have a timer etc. It does give you some forward protection of obsolescence. In 5 years time, the now common USB port will not be very common at all. So for that reason, we are only putting in 3 usb power points and we are getting the latest design of power point with the new form factor for the swappable components.

An example is out here a vertical power switch is cheaper than a horizontal power switch. But the vertical one, just needs the switch module turned 90 deg and it becomes the horizontal for no extra cost. Some brands don't have modules at all, so a whole replacement is required. The modules are around 2/3 the price of the cheap non module switches and power points.

I like the 2amp usb charge ports we have so far and think they are great. The area does not get warm at all and it does not take up a power point to recharge the phone.

Neil

That is a good idea as an alternative to the carriage wheel. Being centred will have advantages as well.

Thanks for the idea.

Neil

I am trimming my pistons on a 1972 Myford Super 7 with 3phase motor VFD controlled with segmented belt drive drive, few would believe me. My smallest reliable cut is 1um on diameter, but have taken 1/2 um cut on diameter when fitting a piston for Glen Lewis. Rob is always impressed by what I am doing off a Myford S7. They had a new one back in 73 or 74 and it was not good enough for their liners or pistons back then. I have however refitted the spindle to bearing assembly, reset the bed clearances, and added a constant gravity oil supply, and refitted the compound slide as well. But nothing that anyone else could not do with time and care. Oh, and made a M8X 0.5mm pitch cross slide screw, but it is a normal RH thread, not the normal lefthand thread that is commonly used. The 0.5mm pitch with the hundred thou dial, makes it read just like a metric micrometer. My lathe is in room at around 20c temp to help with things. So do get there, I have the compound slide on a slight angle, so that 4 thou on the compound is 1um of X axis movement. The original compound as supplied was not capable of this fine enough and repeatable movement, so was reworked to be able to do so. I have a nice 1um 0-30 Tesa micrometer for measuring the pistons with in Combination with small Vee block. It gives a finer reading than just using the micrometer on its own. Another advantage is it allows you to see if the part is round as well. With the liners they are tapered so make for a really good gauge. If the liner is out of round you have to fit tighter to allow for wear etc to get a really good seal. Some piston alloys, even though they are from sintered stock, just will not stay round. So avoid those when possible. Some materials wont keep round to 8 microns or so. Typical taper is 2.5 micron per mm, but some have less taper like 1.2 micron per mm, while other earlier liners had lots of taper like 3.8 micron per mm. The only tool I have found to be able to take the very fine cuts on pistons is the very nice Summitomo PCD insert NF-DCMT11T304N-LD DA1000

Here is a picture of a piston being trimmed before I replaced the rear bearing set and reset the front taper and spindle again. and another just recently. Looking through the exhaust port , you can see the new bearing and refitted spindle is making a much nicer surface finish on the piston. It is hard to see in the 1st pic, but a 1um cut makes very fine sand is the way I describe it. I hand feed at around 0.02mm /rev, it runs around 700 or so rpm, and takes around 1 minute per pass for the less than 15mm length of piston. So that is like around 4 seconds per mm or so or 1/4 of a mm per second how ever you want to work the time/distance out. I don't use power feed as the surface finish becomes junk in comparison and it effects the repeatability of the carriage. Having an old fashion clock with a moving second hand is really helpful in gauging feedrates etc I find. I used to trim with the pison on a fixture and then fitted them to the rod. But with the new press fit pin pistons, the assembly has to be done with the rod in place, so a modified version of the fixture shown with a holder that held the rod and tightened from the back end through the spindle was made. Some days I don't trim pistons, due to temp in the room conditions, or if I don't have the right mindset to do it.

2019

Edited By Neil Lickfold on 07/07/2019 17:09:08

When fitting pistons for race engines where between good and worn out engine is 2um on diameter , being able to turn and fit a new piston without lapping it, shows a performance edge with the stop watch. The other option is to turn a lot of pistons at slightly difference sizes and then find the best one that fitted. In realty, making 4 different pistons of different sizes and then finding the best fitting one, takes the same amount of time, but you have 3 spares that may never be used.

If I could have something that allowed me to turn a piston to 0.1 um, and be round to that tolerance, I think would be really great.

Of course the real biggest issue is having the material that can be stable enough to be sized to 1um or better. Until powder metallurgy arrived, pistons for model engines could not be sized to 1um at all.