Member postings for Neil Lickfold

Thanks for the informative reply.

I have since learnt that the radial run out was due to the class of bearings I brought. It seems there are general, spindle bearings, and a lot better spindle bearings. In my case they were part of a headstock spindle cartridge I made. To get better concentricity will require a better class of bearing with a higher manufactured accuracy. There are other ways of improving the assembled accuracy, like measuring where the high versus low on the shaft are and then aligning it with the high/low on the bearing to compensate . Then there is the final grind/turn of the important faces/surfaces once assembled. I liked the idea of using TRB, but have since found out that the precision spindle class is like gold to buy. The ACB is a new can of worms for me to figure though with the various contact angles and precision.

It appears that the more accurate ones are made to the same tolerance as the cheaper ones, about 0.001 to 0.002 mm but have been measured for their concentricity and marked accordingly .Is this correct?

My goal with all of this is to eventually make a super precision spindle that rotates concentric to 0.001mm or better for another little project I am working on.

Thanks , Neil Lickfold

Ketan, I know this is an old thread, but where do you get high precision and concentric tapered needle roller bearings from ? I had a project recently and the best concentricity I was getting from the Timken Tapered needle roller bearings, 40 ID X 68 OD was 0.01mm , and was not as close as the 0.003mm that was obtained with Angular contact bearings . Both setups used wavy washers to keep a constant pressure with an 0.04mm expansion allowance. Preloading without the wavy washers did not change the concentricity of either setup. Granted these were not brought or ordered to be spindle rated precision bearings. In the Timken range , i was given a ballpark figure of 600-700 dollars each, but needed to be an indent and ordered item. I did not get a price on the AC bearings as the 0.003mm was good enough for what I was doing with it.

Neil

It is not that much more money to have the more accurate scale on the X + Z axis, you can choose if it reads in 2 or 3 decimal places as well, apart from radius or diameter.

Digital readouts have lots of conveniences. Some have the ability to set tool numbers and zero them , so interchanging tools is very easy without having to re zero or reset the tools.

Neil

Is there a particular reason that it has to fit the Offset indicator Holder ? Not sure of quality these days, but the Verdict indicators used to be very good at having the stylis aligned to the centre of the holding shank. A alot more money but a very good indicators are the ones from Interrapid, also very good for the stylis being aligned to the holding shank. I have the Verdict metrinch 0.01mm 0.005 inch, and an Interapid .0001 inch. I also have the Mitytoyo .001mm but it has the dovetail attachments . I find that the dove tail does not align all that well to the stylis centre line , so I use it as a comparator or with another adjustable indicator holder.

Neil L

When I make test pieces, I ruf down the od, then almost part it off, then I finish turn the diameter, and finally part off. That way the stresses in the bar are at the minimum. Some materials are not well suited to make test pieces out of due to the stress in the material stock itself. When looking for small errors it is not quite as easy as it may seem. Anyone who has worked in a metrology lab will know what I am talking about.

Neil L.

From my experience , when you turn a piece in a chuck, part it off, place it into a Vee block and rotate , then you will see the error. Something turned between centres, especially dead centres, should be round on almost any set up. I have a modified Taig type lathe, and when I turn something in it, measures ok with a mic and looks ok with a dti. Then rechuck the part and get it round, just won't happen. I have a 0.001mm dti that use for checking in a Vee block. It is a lobed shape, not triangular and not very round.The Taig has since been corrected with better accuracy angular contact bearings, but even with those is still no better than 0.003mm, but is a lot better than the original 0.01 to 0.013mm it used to be. A better grade of bearing is available, but am not prepared to pay for them .

Neil L

When looking at a lathe, the most important part is how round does it turn a piece. From what I have seen of these Taig lathes and others, is they can not turn to better than about 0.01mm of being concentric and round. The headstock bearings are just not up to it. On the taper bush like a myford, they can be made to be better than 0.002mm. To get that accuracy with precision taper or angular contact bearings, you are paying nearly the price of the machine, just for the bearings.

Neil

There are Ti specific soluble cutting fluid. Like others have said, sharp tools, low speeds and relatively high feeds.The centre cut point drills work a lot better than regular drills. Sharp positive rake carbide turning and boring tools also work very well. HSS works well , but does dull a lot quicker than HSS. As soon as heat starts to build, resharpen the tool or go to a slower speed. When drilling through plate, I put a piece of steel underneath for the drill to break into. On the lathe I try to avoid breaking through where possible and prefer to part off or face off the back end. Ti also expands quite a lot, and is a slow conductor of heat. When drilling the common problem is the material getting hot, and then contracting as the drill is either retracted or when more coolant is poured down the hole.

Neil

Jason interesting post.

So I just got 15 blocks and cleaned them as I normally do, then assembled them. My mic reads to .001mm,

Then I redid the test again, and this time put a thin film of non scented baby oil on them. I got the same measurement.

I really was expecting a measurable error of at least 4 to 5 um. I put together 1.01 to 1.6 and got 17.555mm should have been 17.550, but with the error of the blocks added up that makes it about right. I think baby oil is parafin oil as it just calls it light mineral oil.

Neil L

I use mostly a 1 mm wide hss parting tool in a dickson holder.The blade is hollow ground in top. As I mostly have the holder block true to the lathe axis. I don't use a rear part of because I have a router mount there for use with live tooling. For most things I part off at about 500 rpm and feed rate will be about 0.03 to 0.1mm per rev .I sharpen the front edge only on the tool when it either looks dull or the force required gets a little more than a newly sharpened tool. Steel, I sharpen a lot more than brass and ali. As for coolant, on Ali I us CRC or WD40 or cooking oil. For stel I only use cooking oil.

Never have issues parting things off.

Neil

I am a fan of using the size machine most appropriate for the size of the work. Sure you can do stuff on larger machines, but if you need to change chucks etc on the big stuff then it does not become viable time wise.

I made a Cuemaking lathe, and it has been alot more used than I thought it would be for working on small diameter stuff, but quite long.It has a48 inch bed and the headstock is ER40 with a through hole of 30.5mm. I have an adapter that then allows for the 3jaw or 4jaw Taig chucks with the 1-9/16 X 32TPI thread. Lately I have been making cue parts with it, but have made parts for tuned exhaust pipes and even did a work job once of squaring up the ends of some 400 mm long or so shafts between the two steady rests. All the accessories are quite light and easy to work with and change around. With care you can turn something to about 0.01mm in diameter and about 0.01 on length with great care. If I need better than that, I use my Super 7. A lot of things I hold between the 2 steady rests, then drive it with a drive dog, and then can bore and drill out the inside with ease, knowing that the work piece is in a relaxed unstressed state. The large steady uses a single bearing with a 68OD and 45 ID. Down side is it has no thread cutting capability.

Neil

The best of the ER collets are made by the BiG company in Japan. The Australian collet is like an ER series but has an 8 deg included angle not 16 like that of the Rego Fix design.

To make home made specials, the ER32 are easy to make in the home shop.

As to holding power for cutters, the Australian 8 deg included taper have more gripping capability, but the cutter body needs to be engaged for the full length of the collet like that of the ER series.

Neil

For the glow plug engine to work nicely, a real compression ratio of about 9:1 to 10:1 works very well.

The glow plugs only need enough to glow about a bright red, Not orange. Most glowplugs only require about 0.8 to 1 volt dc with a current draw of 2.5 to 8 amps, depending on the wire thickness and type.

Nicad batteries work well, but so do NiMh. I would recommend if you are using the 2volt cyclon batteries, that you use 0.15 ohm resistor if it is a higher current draw glow plug or a 0.2 ohm resistor if you are using the lower current draw glow plugs. Generally the higher heat range glow plugs have a low current draw, and the colder heat range have a higher current draw.

Running the engine on glow fuel will generally result in a cooler running engine. There are glow plugs designed to make the engines run with petrol instead of the methanol based glow fuel. These engines make a little over 1/2 the power of a glow fuel engine, and generally run a little hotter as well, but do have a good range on the tank capacity.

There is no adverse effect of leaving power on the glowplugs while the engine is running. It just flattens a battery. An enelope AA rechargeable NiMh battery will keep an engine running and restarting for about 10 to 15 mins depending on the heat range of the plug.

Neil Lickfold

If it was me, I would use a 10mm centre point sharpened drill, at 150- 200 rpm max, and 0.1 to 0.18mm per rev with flood coolant. In the past I have had best results when doing thin shims like you are doing is to have a 1/8 or so plate as a top plate and base plate.This stops the top shim layer from lifting up. Keeping the stack short reduces total heat build up.

Basic rule of thumb is 1/2 the speed and twice the feed.

Neil

I use SR44 or 357 cells for my Calipers. The SR 44 and 357 are Silver Oxide batteries. They have about 170 or so mah capacity, compared to the LR44 that has anywhere from 60 to 110 mah depending on manufacturer.

The 357 have a lower internal resistance and are used in camera's. So for me it is easier to just buy 1 part and use it in all my devices.

I do not bother turning off my calipers as they are the older type that need zeroing when started, apart from the newer solar powered one. I get about 18 months on my caliper brought in 1987, but only get about 1 year with the 2003 brought caliper. Not sure why the newer one uses more power than the older one. It may be that the newer 2003 one remembers it's last zero setting, Either way, the saving of turning them off is just not there to me, compared to the convenience of just using it.

Neil L

Another way is to make a broach , so that as it is pushed through keeps opening up the corners .

A broach is fairy simple to make , a one pass from broach will work as well, but there are situations where these are not the best way.

There are square drill setups that use a triangular drill bit etc, but they do leave a radius in the corners.

That is because they are not really making a part, but rather using it as a demo on what various types of processes and things that the machine is capable of being programmed.

The offset hole is just to show control between the rotating axis and the mill head rotated 90 deg.

Neil

I don't have access to that.

I have the latest model engineers workshop, but did not see any such article.

Neil

What was the outcome and how did you go about the job?

Just curious.

Neil