Member postings for Neil Lickfold

It is interesting about brands and type of equipment. If it gets the work piece close enough for what you are doing than it is fine. It only becomes a problem when you are trying to indicate something and the indicator can not reliably put the part to that level of precision. You then either buy a new instrument with a finer reading amount, or make a design your parts in such a way that you are not reliant on the indicator for the precision. I did buy many years ago a Chinese finger type indicator with a 0.01mm reading. It would show after about 3 months that the work piece was indicatored to better than 0.01mm, but was actually out by 0.02mm. It went into the bin. The Tesa indicator I brought to replace it, is still very good and I check them about 3 times a year for repeatability and incremental reading error. An example of needing better reading indicators is when I modified the bearing races. It was a lot easier to indicate the inner race of the bearing to be reworked with a 0.002 mm indicator as to using the regular 0.01 indicator. Trying to gauge a 1/3 of a reading on the indicator is really for the very young eyes. With the 0.002 indicator, that becomes 1.5 divisions, much easier to see for sure.

Neil L

The tools to assemble the bearings with and the to get the front inner assembly together etc.

You can see the rear bearing puller and the assembled front inner race in the clear assembly housing. The hollow aluminium bar in the centre at the bottom, pushed the inner race and it's compliment of balls into the front outer race.

This is the crank and modified outer race assembled with ceramic balls in place, awaiting the heated case to be placed over the assembly. It is the easiest way to get the rear outer bearing shell into the case.

And when the case has been assembled.

Care has to be taken as if the shaft moves back in the case a few mm, the balls will fall out.

Crankshaft polished with balsawood mounted onto 1/8 shaft and 3000 grit diamond paste. These cranks have the inner race as part of the crank shaft, also know as an integral bearing crank.

I have set out to modify the the outer bearing races of 10X22 bearings for us in a 2011 Proi 2.5 cc speed engine. I want to change the existing that uses a 10X22 outer race with the polyamid cage and 9 balls to a cageless near full compliment ceramic ball rear bearing and a cageless front bearing. Both the rear and the front bearings become magneto bearings. The rear bearing taking the axial thrust and the radial forces of the crank assembly and the front bearing taking the radial forces and controls the amount of total endfloat between the two.

I made a fixture of sorts, that holds the outer ring while it gets turned. I made the inner bore of the shell holder slightly less than 0.01mm smaller than the outer diameter of the bearing shell. I used castor oil as a lubricant to assemble the ring into the fixture and had a clamp ring to aid in the assembly. Then I bored out to the diameter of the ball race to the centreline from one side and then diamond polished it. There is a ring inside that allows the extraction of the outer race. Some assemble tooling was required and some more tooling required to measure the position of the crankshaft to the front bearing seat. Other tooling to measure the position of the inner race to the outer race position as well. Instead of making shims for the outer race of the front bearing, I turned the end of the race shorter by the measured amount.

I have some pictures of the tooling and the shaft and case. The project worked better than I thought, and had a RPM gain of 300 to 400 rpm. I did not think that the cages could be producing enough drag to make that much difference. The idea of the project was to get a longer life from the integral bearing crank shaft, and a longer life from the front bearings. Im not sure on the front bearing life just yet as it has only done test bench running. The other engine with the home made outer bearing shell of the same design but using 2.5mm ceramic balls is lasting very well so far. This one uses 1/8 ceramic balls, so I expect this set up to last a longer time.

Fixture and Modified 6X15 outer shell. Turned using Kyocera insert ccgt060202mp-ck pr1425 on a 10mm shank boring bar at 500 rpm 0.1mm cuts 0.2mm diameter at a time.

Check this out from DMG Mori. https://www.youtube.com/watch?v=g8sT8ESfjrg

The new way of the future for manufacturing high tech things.

Neil

Taper pipe taps and dies are a lot easier to drive compared to a regular tap. Also most pipe is free cutting mild steel.

Neil

I had a look at my chuck, it has belleville type washers under the cap screws holding the chuck together.

What you say does make sense about the body screws. I have never has any issues with my chuck though.

Glad to hear the OP has found the cure to getting it running well again.

That sized tap will be hard work in anything other than free machining. As been suggested, screw cut to size, but with a full form threading insert makes internal thread cutting that size quite a simple operation. It will take quite a bit to even run the tap through to clean up the thread to size. Buying a 1.5mm internal threading insert and holder will be worth while if you are making quite a few accessories. The advantage of screwcutting is that the thread will then be true to the faced reference and location diameter.

Neil

My main Griptrue chick is about 30 years old possibly more, the new one is about 20 years old. I have hardly used the new one. I have the outside jaws on the new one and standard jaws on the old one. I just change chucks instead of switching out the jaws. One thing that I thought of when I 1st got the lathe as it came with this chuck, was to adjust the chuck with the least amount of pressure to hold the part true. I think they can be damaged by over tightening the adjuster taper screws. When ever I need to hold something very tight, I use the 4 jaw chuck for that. I rarely need the 4 jaw.Over the range the old chuck is upto 0.05mm tir out. But if zeroed in on a size it is still better than 0.01mm every time. I have not taken it apart for a service yet, but will do after reading the info and articles. Here is a picture of modifying a 6x15 bearing outer race to become a magneto bearing. The bearing is a very light press fit into the fixture with castor oil to allow the over size part to assemble. There is an extractor screw to take out the bearing shell. It was set up in the Griptrue because if the inner race did not run true to the outer race, I could adjust it to be true, then I could turn away the part of the bearing to the race center line. It happened with this bearing that no adjust was required.

I use baby oil to lube the insides of my DTI's . Seems to work a treat.

Neil

I like using the dimple bars by Mitsubishi/ Kyocera or the vibration dampened bars from Sumitomo. I have done my own conversions on some tools by drilling a hole into the tool and then filling the hole with a lose tungsten carbide weight. They work very well at reducing the vibration from the tool and give a much better surface finish. Sandvik also do their range of tunable boring bars that are oil filled and have a piston that is screwed in and increases the pressure inside the bar.

Neil

Dean, can I call by and see it the engine ?

Just send me a PM if you want.

Neil Lickfold

Post a picture of the tool you are using. It is much easier for people like myself to be able to give you constructive feedback on the changes that will be required to it geometry or the way it is made. Sometimes very small geometry changes in a tool will have a big impact on it's effectiveness which is not always obvious especially to beginners or people who seldom ever make that style of tooling.

Neil

Guhring make a huge range of drills, some for specific materials. We use a lot of Guhring drills at my place of work and we have different ones for different materials. They are very well made tools and if you run them correctly get a lot of holes drilled per drill. They also drill very well to size also. Once re sharpened if they are not recoated, then I use the feeds/speeds for the uncoated drills.

Guhring also offers custom tooling for specific tasks as well, that most other companies do not offer to do.

Neil

I had a test piece checked on a Talyrond machine a couple of months ago. The result was better than 0.003mm , so I was very happy with the results. I was going to replace the main spindle bearing, but decided to scrap and blue it to the spindle some 25 years ago or so. I am still very happy with the machine.

Neil

Stubs Silver steel is more commonly called W1 as it was a water quench hardening steel.

There is also O1 steel which is an Oil quench hardening steel. Some companies sell centreless ground round stock that is actually O1 steel and name it Silver Steel. The Stubs Silver Steel that I have seen comes in 36 inch lengths.

Neil

Edit, It should read 0.5mm per 40mm, not 0.05mm. Not sure how to edit the post to correct the wrong data.Neil

Old School, This is the RSA-444 piston material, 30% silicon. With these hypereutectic alloys with high silicon, carbide will not take fine cuts on this material. I finish the end face/ piston crown and rough the outside to about 0.1mm diameter. I then change to the PCD, insert is NP CCMH060204 MD220 , it is a 0.4mm radius and is positive cutting. I chose this small size because of the positive cutting geometry which I could not see in the larger 9mm insert . image here ,http://www.mitsubishicarbide.net/mmc/ja/turning_inserts/no_srs/20043582 I used RiceBran oil in a spray can, usualy us canola oil but ran out, so grab what was in the kitchen. Now have to buy another, she won't use it because I had it in the shed.My win. Anyway, I learnt something new in trimming these pistons. Normally, I have to clean the piston and liner with contact cleaner to get the oil off to work out the dry fit height of the piston. But with the rice bran oil, if I just blew the piston off with compressed air, made sure it was clean and tried the fit. I could get the same fit if I cleaned it all with brake clean or if I just blew off the micro turnings.The diamond insert is expensive, but well worth it. I run my myford at about 500-600 rpm, top speed in the low main pulley. The cut is put on by winding backwards the compound slide. On my one, each division is 0.04mm of pitch, so the slide is set at 0.05mm in 40 mm of travel of the compound slide. I turn the main diameter to about 0.02mm of size, then do not touch the cross slide until it is finished.The cross slide centre gib screw is tightened slightly to not make the axis so free on the hand wheel. I keep oiling the saddle slide quite often as well. after the cut, I wind the compound handle exactly 1 turn forward to bring the tool away from the work piece. I hand feed the saddle at a rate of about 30 seconds to cover the 14 mm or so distance. Measure or try piston and then take another pass. The tool is set as close as I can get it to centreline. Neil

Here is a piston I am trimming for a friends model diesel engine, 2.5cc

I set the compound over to about 0.75 deg, it is actually at an angle so that
every 0.04mm that the compound moves backwards is 0.001mm diameter cut.
With a dti it is set at 0.05mm per 40 mm travel.
One picture shows the colour change with a 0.003mm diameter cut and the other shows the liner at it's
fitted position and the oil colour change for the amount taken off to fit the piston 0.5 mm more up the bore.
The bore taper is about 0.00061mm per 1mm of travel, so about Ø 0.0012 per 1mm travel.
Measured taper is Ø 0.012 for 10mm