MEW 239

Having, on previous occasions, called into question the direction which I felt Neil was taking his magazine , I would like to complement him on this issue ( 239 ) which I thought was especially good. I look forward to many more in a similar vein, Well Done Neil

Much appreciated.

I am really keen to receive brief but complete practical articles like those in Issue 239, especially designs for small tools that have complete plans and relatively concise writeups.

Neil

I fully support and endorse the initial comment and found that the content of issue 239 was exactly the format I have been looking forward to seeing.

Well done Neil and team.

I agree with Mike. I have enjoyed this issue far more than any of the recent others. It is like the MEW of the first few years. It may encourage me to keep on subscribing.

Well done, Neil, and thank you.

Agree with the above, excellent issue,

Well done Neil.

Paul

from me, too.

A great mix of articles ... although the Carversaw did make me a little envious of Mark Noel's 'Refuse Amenity Site' [or whatever we call them this week]. ... What an enlightened attitude !!

For comparison; the jobsworth at my local site flatly refused to let me take [or buy] the lens and mirror assembly off the column of an OverHead Projector "because it's a piece of Electrical Equipment".

No ammount of explanation would get me anywhere ... "Rules is Rules"

MichaelG.

Edited By Michael Gilligan on 24/02/2016 16:22:08

I too was envious of the Amenity Site's attitude.

If you are caught removing anything from our site you will be charged with theft.

The Isle of Man has its own government and laws... it isn't even part of the UK!

Neil

I believe they are called Civic Amenity Sites after the similarly named legislation. Where I live they can only be used by car drivers, a strange position.

I too enjoyed this issue more than most (and I enjoy most issues).

Can I make a couple of (hopefully) constructive comments?

As a beginner I sometimes struggle with the context of a story. For example, I now know how to make a spring centre, but I have no idea why I would want one!

As another example, I can see how to make the lathe stop, but I'm not really sure what to do with it once it is made. Is it something I Could use with a power feed for example? I'm about to do some largish turning on my lathe which will need to use the power feed and want to stop at the same point as I turn down a 40mm bar (up to a point). Do I spot this by eye, or should I make something which cuts the motor at a certain point?

I rather suspect most of the readers will be much further ahead than me so probably don't need spoon-feeding so much but perhaps others have the same struggle.

I loved the centring a 4 jaw chuck story - I've kind of given up on mine due to not having a clue. and I found something helpful in pretty much all the articles.

More like this!

Iain

No, that's a good point there Iain. I don't think regular readers would object to a few extra lines of explanation.

I will try to remember to prod contributors into better explaining what their devices do!

The spring centre has the main use of supporting a threading tap, but it can also be used to support an ordinary centre which is being used to align work in a 4-jaw chuck as shown near the end of the article on that subject.

The stops shouldn't be used under power - they will either move or something could break. Either disengage power feed before you get to the stop and finish moving the carriage by hand, or do the whole cut by hand.

You could use the same principle to make moveable mounts for microswitches that could be used to cut the power, if your lathe has provision for wiring low-voltage switches for this purpose (some do, most don't and need more ambitious electrical modification beyond the scope of a brief reply).

Neil

I was given a battery powered hedge cutter, because the chap had lost the charger ! Got in just before it went in the skip, so legal. The carving knife conversion has given me an idea, the motor should have enough power ,but the stroke will need altering. Always fancied a power hacksaw.

Iain

Normal practice when using powered and fixed stops is to follow the last part of the power fed portion with your hand on the saddle feed hand wheel. You drop the power feed just before you reach the stop and do the last portion by hand. It takes very little practice to get the knack of switching your hand from following to actual feeding giving a near seamless transition and almost constant speed so there is no witness line on the turned surface at changeover or variation in finish afterwards. If you stop powerfeeding then finish off by hand a visible witness is invariably left and the actual finish left on the workpiece will vary due to the change in feed speed. By eye it will stand out a country mile but if your lathe is in anything like decent shape and the tool sharp with no built up edge you won't be able to feel the difference. If I do the stop power then finish by hand with my Smart & Brown 1024 a 1/10 th thou indicator needle barely twitches when passing over the highly visible witness line!

I've always felt that a micrometer is an essential part of any stop system. Makes it easy to get things exactly the right length.

If you decide to make an electric stop containing a microswitch to turn off the lathe motor at the end of travel its important to have some overtravel capability giving time to intervene should it fail to function for any reason. Simply running up against the microswitch button is risky. Standard practice for this sort of thing is a spring loaded rod running past a microswitch with roller type lever actuator. The rod is in two sections. One small so the microswitch isn't actuated and one larger so that it is with suitable transition cone beween them. I guess something like half an inch of extra travel after the official switch operating point should give enough time for manual intervention if needed. One disadvantage of this layout is that the cone actaution is slower and less precise than a direct push on the button so the end point will vary a bit, maybe up to 20 thou, 0.5 mm scatter with a good microswitch. Another is that you are setting travel distance against a spring, the inevitable flexibility means its not as precise as going against a hard stop. Perhaps a setting shield covering the sprung pluger to give a hard stop when setting up is needed. But thats another thing to loose in the chip tray.

The obvious way to install such a device is via a jack plug or similar with built in mechanically operated changeover contacts. Plugging in the switched stop automatically puts the switch in circuit and removing it restores normal function. Simple and inexpensive but potentially dangerous as it fails hard with the switched stop out of circuit should the plug not operate the internal contacts. Such failure leads to an unpleasant surprise when the switch doesn't operate as it should. I've been considering such microswitch stops for both my lathe and Bridgeport milling machine but haven't yet come up with a neat way round this problem.

clive.

Edited By Clive Foster on 25/02/2016 13:16:41

You can get 'roller lever microswitches'.

Neil

Neil

Something like this would work.  About 1/2 inch overdrive on this one, came to of a spin drier lid mechanism.

Sorry about rotated picture.

Clive

Edited By Clive Foster on 25/02/2016 15:03:47

I have some electronic skills and some optical switches (OPB625 and OPB916​ I think) and should be able to cobble something together - as and when. I'm not certain if the switch would provide the right level of repeatability though. The spec sheet only covers the electronic aspects.

However, for my application (a lathe spindle) it is effectively going to be a 'pyramid' with the large end at the chuck side and the small end at the driving side, so I think what I will do is to use a parting tool to mark the end of a level (and a bit deeper than my target) and slow down or stop when it gets into that zone.

I seem to have spent a lot of time fixing or modifying the lathe and making tools and very little building my project!

Thanks for the tips, though.

Iain

Iain,

First law of serious model making, don't expect to work on a project all of the time, there are always tools and special setups to be provided, at times the project will only be 10%.

To be honest, the tools are the most fun part - that and learning techniques.

I'm not actually doing this hobby to make products (that's my day job - sort of). However, She Who Must... thinks I should be building things and it makes my life easier if I actually, sometime, can point to something and say, 'look'....

It would, however, be nice to do that sometime in 2016,...

Iain

Don't over think it, it's only February.......................................................