Member postings for David Littlewood

I usually treat my machine tools, steel items of workshop equipment and part completed models with Shell Ensis anti-rust oil, wiped on with a soaked rag. It seems to provide very good protection, but can easily be removed for painting with white spirit or similar solvent.

David

Ronan,

I have a Harrison M300, which is virtually equal in dimensions to the Colchester Master (though not quite so substantial) so I know what you mean about it not being ideal for turning very small parts. However, this position becomes a whole lot better if you use a collet chuck instead of a conventional 3-jaw. Probably the best choice would be an ER32 chuck, you can get an excellent full set of collets for around £100.

For a scaled-up engine, I was quite intrigued by an example at the back of the Building Victoria book - someone in Africa (I think) had fabricated a 2x version and was using it to provide power in some remote location. No constructional details given though.

David

Alex,

To be brutally honest, if you don't know how to do it, you should ask someone who does; messing around with mains voltages is not a good way to learn. To improve your knowledge, get hold of Jim Cox's books in the Workshop Practice series.

Anyone notice that the motor data plate has a howler on it? 0.18 kW is a quarter HP, not 1.5 HP (or conversely, 1.5 HP is 1.1 kW, but given this is for a Peatol I would assume it's the former, which is also consistent with the mains input current).

David

Edited By David Littlewood on 11/08/2012 14:49:54

Russell,

Quite right, my mistake, I apologise for the confusion. Shows the danger of replying to these things sitting at a computer and relying on memory, instead of actually going to the workshop to check. I hope the mistake would have become obvious to anyone who watched the scroll going round.

David

Edited By David Littlewood on 11/08/2012 12:34:27

Will,

I'm afraid Hansrudolf is quite right - I was not suggesting use of a file inside a bore, that would be doomed to awful results. I was suggesting making the bore (reamer, boring head, hone, whatever) and then adjusting the shaft to suit using a very fine file. I apologise if this was not clear.

Don't try this using the bog standard files described as "medium" or "fine" ; these are suitable for metal removal but not for fine surface finishing. Genuine Swiss files of the finest quality come in numbered cuts, 0 to 6 - mostly the even numbers only are found, one occasionally sees odd numbers. I use for preference a No 6 cut hand file; this has a rectangular section and one safe edge (but check it - may need slight attention from a stone) and leaves a finish like the finest cylindrical grinder. I can easily take less than a tenth off the diameter, and the amount is small enough that it's reasonably easy to maintain parallelism.

You will find that genuine Swiss files (and I don't mean the titchy needle files often called Swiss files even though most of them aren't) are hard to find, and the No 6 cut is the hardest of all; when you do find them, the price may take your breath away. The only source I could find in 5 minutes Googling was

**LINK**

And look under "Files - Pillar Standard (Swiss Vallorbe)" for the 150 mm No 6 cut - £35.65 + VAT. I tend to keep a couple of spares in stock as they don't last forever and are hard to find. You can get nearly as good a result with a No 4 cut, bit easier to find (and cheaper). Keep clean (bit of brass run along the grooves is the best - the brass will soon acquire a set of teeth to match the file's tooth profile).

The steel/brass thing is important. If you want to use a file on brass, never use it on steel, this will very slightly take the keen edge off the teeth and then it will skid badly over brass.The counsel of perfection is to save a new file for brass, then demote it to steel when it starts to lose its first freshness.

Always use a handle when using a file on a moving part in a lathe; your wrists are at serious risk if you don't. Holding the part in a collet is strongly preferred as there are no nasty chuck jaws to hurt you.

For fine finishing of bores, I suggest you use a cylinder hone or a lap; I'll leave you to research that topic.

David

Edited By David Littlewood on 11/08/2012 12:29:53

Merlin,

Diamond wheels are, in general, totally unsuited to grinding steel of any description; have a look at the link I posted above. You should get a decent white alumina wheel.

David

Jason,

If you expect retailers to always use the right word, you are obviously more of an optimist than I am.

David

If you buy a copy of this book - it's only a fiver - it has some very good colour photgraphs of metal at the relevant temperatures, far more useful than any attempt I could make to describe them in words.

**LINK**

david

Jason,

I think you are cofusing carborundum (silicon carbide) with corundum (aluminium oxide). Grey wheels, AFAIK, are aluminium oxide, not silicon carbide.

David

I think this reference **LINK** is fairly clear - and tells us that grey is commonly used for alumina wheels for fairly rough grinding. Now I come to think of it, my original bench grinder had coarse grey wheel on one end and a fine white one on the other.

David

The most common abrasive in grinding wheels is alumina (aluminium oxide), and the wheels made of this are most commonly white, sometimes pink, and possibly other colours. This is fine for grinding steel as alumina is harder than steel.

It is not though hard enough for grinding tungsten carbide. The only commonly available materials for grinding this are silicon carbide and diamond. Green grit wheels are silicon carbide in a soft matrix. They do grind tugsten carbide, but slowly and with rapid wheel wear; they are really old hat, and diamond wheels are cheap enough, longer lasting and faster working.

Stick to alumina wheels for HSS and diamond wheels for tungsten carbide. You supplier should be able to guide you as to the best grade, but a middling grade alumina in a vitreous medium should be fine.

I don't know what the grey wheel signifies, you need to get him to be more precise. If it really is grey I doubt it is silicon carbide, but he must be able to tell you precisely what it is - he has no business to be selling grinding wheels if he can't.

David

Edit - DC's post appeared while I was composing this - he has asked the most sensible question of all!

Edited By David Littlewood on 10/08/2012 18:05:44

It's also worth looking on the Homeworkshop site:

**LINK**

every day or so, as although there is not the same volume of stuff on there, it tends to be from sellers who have taken care of it, and prices are mostly more reasonable. For those who don't know it, it's a great site, run on a not-for-profit basis by volunteers. Stuff does seem to sell extremely quickly though, so if you see something you like, don't hang about. Most sellers are perfectly happy to let you make a provisional reservation subject to inspection for large items like lathes.

Good luck!

David

Terry,

In theory*, it shouldn't matter. What is important is that you push the number 1 jaw into a slot and get the start of the scroll to engager the first tooth. Then, before the scroll front reaches the next slot clockwise, push the second jaw into that slot and rotate the scroll just far enough to grab that jaw; proceed similarly with 3 and 4. After engaging each jaw, give it a good tug to make sure it has actually been engaged; if not, back off the scroll and try again. You will know if you have done it correctly as if you haven't, the jaws wont all meet in the exact centre.

One some chucks I think the No 1 slot may be marked; if so, use it and then go round clockwise. It may also be interesting with an unmarked body to use each slot in turn as No 1 and see which gived the lowest runout. Then, obviously, mark that as No 1.

David

*Obviously, there may be cases of poorly-made chucks where this is not true.

Edited By David Littlewood on 09/08/2012 16:46:49

Link didn't work for me.

David

Gordon,

Lignum vitae is an excellent wood for bearings, so if you have any old bowling balls which are not fit for purpose, don't be too quick to give them away, save them against the day when you want to use them in this way. But if you do insist on getting rid of them, where do you live?

David

Just an afterthought - I find a carpenter's bench hook makes a very good bed protector when removing a chuck. If you don't happen to have one, it's cheaper to make your own, but if you do, it saves making one.

David

Michael,

The Kennedy monorail certainly looks a desirable collector's item. Like the writer of the first site you quoted, I suspect it could be quite tricky to operate; having spent many hours back in the 90s taking photos on a 5x4" sheet film technical camera, I remember how critical it is to get the focus spot on, and how tricky it is on the ground glass screen. I hate to think how much more challenging it would be with a 35mm image (36 x 24 mm max). Also, the design would seem to require use of lenses designed for larger format cameras (to fit the leaf shutters in the lens board. The generally have a markedly lower resolution than those designed for 35mm film - they don't need it.

Still, wouldn't get rid of it if I had one! Thanks for sharing.

David

Gordon,

You can get a hand-turning rest for a Myford 7 series lathe, and no doubt one could easily be contrived for most other models. This kit:

**LINK**

is an example, but I'm sure you will find some ready made ones if you search.

David

Edited By David Littlewood on 03/08/2012 14:15:15

Michael,

I think I'd need to lie down in a darkened room with a cold towel round the head to follow that. I suspect the degree of automation was largely if not entirely for the purpose of quantity production; for our purposes, mostly requiring one-off or very small numbers, there are much easier ways to cut multi-start threads.

David

Edited By David Littlewood on 03/08/2012 12:50:08

Mick,

You correctly advised that climb milling should be avoided (except, as DC pointed out, for very small cuts) but your description of what it was is confusing. Conventional milling has the tooth sweep up the curved surface from what might be called the bottom of the cut; climb milling has the tooth hitting the top of the cut and sweeping down the curve and back.

The left-right and right-left bit is wrong; you can do conventional cutting in either direction: to move the metal L-R past the cutter, it must be at the front and the cutter behind, and R-L it must be at the back with the cutter at the front. Some people like to go round the outside and then inwards in a spiral, but I don't as I can only use power feed on the X axis, and that gives a much better finish.

David

Edited By David Littlewood on 02/08/2012 11:06:59