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Member postings for MW

Here is a list of all the postings MW has made in our forums. Click on a thread name to jump to the thread.

Thread: Turning plastic bar
05/08/2016 05:07:37
Posted by JA on 04/08/2016 22:42:59:

I have not had problems turning Delrin but have found PTFE difficult. The first few cuts with a freshly ground tool are great producing a good finish. After that the finish becomes poor and eventually the PTFE tears. I have a feeling that the local heat at the close to the cutting edge of the tool produces very small amounts of HF. The amount HF produced being so small that it is not significant as a health risk, rapidly reacting with anything it can find, but enough to take the edge off the tool.

JA

Try taking all the material off in one cut, small cuts can be ineffectual due to the plasticity. You honestly don't need special tools, your normal turning equipment should be more than up for the challenge. If you can remove the swarf quickly enough then your bar wont suffer ill effects, this melting mainly occurs in drilling when the swarf gets stuck on the outside of the lips and flutes of the drill. 1500 rpm should be sufficiently quick.

Michael W

Edited By Michael Walters on 05/08/2016 05:20:00

04/08/2016 20:23:51

Honestly, I think you should be okay with your normal turning equipment, i wouldn't say there's a best but i use carbide, you could try diamond coated drills for glass filled if you're worried about a decent finish. Keep the speed fast. 

Michael W

Edited By Michael Walters on 04/08/2016 20:25:37

Thread: CE marking and Brexit
04/08/2016 20:20:50

These are not the droids we are looking for.

Thread: An unusual mini lathe repair...
03/08/2016 19:45:42

A good idea with a daring color to match. Is that some sort of mesh between the layers?

It may not be essential but i couldn't stand to look at that rust if it were my machine.

Good to see some designing spirit elsewhere in the community.

Michael W

Thread: Power Feed to Milling Machine Table
03/08/2016 13:19:39

Would using a DC shunt motor be a good idea, if not a little big?

Michael W

Thread: What did medieval/renaissance lathes look like?
03/08/2016 11:24:13

Yes, if you look at alot of the ancient monuments, and think of the inventions needed to make them also, Then you pretty much drive a coach and horses through the idea of "biological needs" being the primary driver of invention, clearly the pyramids in giza were never needed as such but the egyptians went to great lengths to design pyramids and tombs for themselves.

This kind of creativity can be witnessed in every society of people no matter how old. Even (and i don't say this in a derogatory sense because there isn't alot of proof they were dumb) the neanderthals had their own culture, due to interbreeding this has made their extinction causes unclear.

It is probably impossible to put a date on when people began being creative and develop culture because it seems to be inherent in our nature. Most skeletons haven't been found any older than around 200,000 years, but i suspect we will find older ones yet. The geological impact on the state of the remains can render them unrecognizable.

Michael G made a rather good point about the distinction between need and want (the separation of the two in the popular mindset was probably caused by the early labour party with their "social ills" campaign and perhaps even earlier with the christian concept of greed and gluttony) It's quite clear that we can create the need or desire for absolutely anything we wish and our bodies will adapt to that.

I have said before that i wager that the most interesting digs and discoveries are to be made right beneath our feet, the problem is we're still using the ground above! But if it's a good place to live today, it probably was a long time ago too.

Michael W

Thread: Power Feed to Milling Machine Table
02/08/2016 23:42:42
Posted by duncan webster on 02/08/2016 23:23:01:

Feeding too slowly results in cutter rubbing rather than cutting and going blunt very quickly. Tubal Cain's book (Model Engineer's Handbook) has useful table giving cutter speeds and feeds for various cutter diameters and materials.

I suppose you could say it's a steady medium you're aiming for, basically fast enough to keep a cut going, it should be working its way through the material, not dragging at snails pace, at the same time forcing the tool to work is quick way to not blunt it, but break it!

I find that for most turning cuts are done in a continuous motion and drilling or parting off can be interspersed with occasional retractions to ward off heat or apply oil.

Michael W

Thread: What did medieval/renaissance lathes look like?
02/08/2016 23:24:04

Well "my life!" As some might say, it's certainly given me alot to look at, theres something quite enchanting about watching the bow lathe turner work on the king piece in marrakeck, it's so simple yet the results are marvelous, his chisel certainly looked mighty keen though!

The reciprocal motion isn't something i considered, and my entire mindset about lathes revolved entirely around the continuous motion concept, the evidence that Romans had considered this and especially the ever famed leonardo had drawn a treadle lathe is simply startling,

it's pretty much the simplest form of a modern lathe i can imagine, meaning, if i had to make a lathe out of what i could find in my garage, that's what i'd be going for. One larger foot pedaled wheel turning a smaller one mounted on a bench between two centres and a rest.

Having said that, it did note on the history website provided by Martin Kyte that it would turn far too slowly for turning work. In an attempt to justify leonardo's drawing, I would say knowing that he had a penchant for coming up with unique designs (that he could sell to provide a living for himself) i would argue he wouldn't be naive enough to not realize that, he never intended for it to be a simple turning machine.

I once picked up an old victorian book on "ornamental" turning in my town bookshop, the illustrations showed spiralled columns turned from ivory, and it listed an extensive list of devices for accurately creating very fine pitch spirals, it shows how during this age the limits of turning were pushed.

Now, leonardo living several hundred years earlier, would've been in a position to market a special machine designed to turn much slower so that intricate groves could be more closely controlled than a faster turning machine. I could never verify this, but unless he was just using artistic license, i find it hard to imagine he would not realise that an extremely large drive wheel would not turn the machine too slowly for normal usage.

Michael W

02/08/2016 13:39:23

This is probably a question for both people who know their materials and also those who have an interest in history.

We know that in earlier times, pre-industrial, that lathes did exist and the evidence is in the items made with them, particularly wood and soft stones, maybe even some bronze, copper, silver and gold items too. Ever since you've needed a round wheel or pottery you can almost assume they knew what a lathe could do. 

What is thin on the ground though is the evidence for the machines themselves or perhaps even the interest in them. I wonder, such as materials which became relatively common in the industrial age, such as cast iron and fine iron, were once considered uncommon, not because the iron wasn't there but the equipment to work it was rare, due to it's higher melting temperature.

Before lathes could be driven by a watermill or steam plant, the instrument itself was almost considered a two person machine, one to carve and the other to drive. Some mills could be driven by animals so maybe a similar arrangement was made with a beast of burden. 

 

I wonder, in a modern sense, we worry about things such as rigidity of the machine, didn't they atleast eventually, come to the same conclusion, that a good lathe needed a solid rigid base from a material that wasn't uncommon and could be worked, why was stone never considered as a material for a rigid base? (for me at least, it ticks all of those boxes.)

So it took a long time to get there but there are these considerations before the question is immediately dismissed as odd and irrelevant. It could create some interesting discussion!

 

Michael W

Edited By Michael Walters on 02/08/2016 13:46:44

Thread: CE marking and Brexit
01/08/2016 21:23:53
Posted by Michael Gilligan on 01/08/2016 19:09:53:
Posted by Neil Wyatt on 01/08/2016 18:59:37:

I think the ONE change we will all welcome is that it will be possible to have 'Buy British' campaigns again!

.

Sad though, that so much of British "manufacturing" involves the assembly of imported parts and slapping a sticker on.

MichaelG.

I wouldn't have such nonsense under my watch. When i say made, i mean made in Britain! yes

Michael W

Thread: A very accurate lathe quick change tool holder
01/08/2016 20:43:08

pounds per square foot/inch was a much better system, It's easy to understand how much force is involved when you imagine it. Originally, like most imperial systems it was based on real life examples. A pound/s weight applied on the leverage of 1 foot long scales.

Thread: CE marking and Brexit
01/08/2016 16:20:36

On a technicality we are still members of the E.U until the negotiations are settled, presumably in the culmination of an amnesty for those foreign citizens who are already here and those Britons abroad, this would need to be limited though if done properly, to make sure the treaty can't be abused in practice.

It could be decided that many of the laws initiated under the E.U would still be adhered to and a formal legal arrangement would need to be setup in order to make sure new products still comply to the C.E standard.

This would be completely necessary because if we were to ignore the legislature and simply carry on as normal, there is no formal framework on which to base our own quality assessments in the future.

I imagine that the full disentanglement will take around 10 years. We will need to decide on everything we wish to keep and enact that, and discard everything we don't want.

So as you can see, the question is never "will we" have a CE mark, but more like "how and what form will it take".

The UK has on the most part been a very negotiable country and it's more a question of how open the other parties are to discussion rather than the other way around.

Michael W

Thread: Boiler Testing
30/07/2016 11:56:51
Posted by colin hawes on 30/07/2016 11:47:50:

There should be no brass directly attached to the copper boiler and, yes, a bare boiler is required for the cold examination and the initial test at twice working pressure. It is likely the pressure gauge and obviously the safety valve(s) cannot be in place. Colin

I think anything brass above the waterline is fine. Of all the things on this forum, this seems to be the issue people and busybodies tend to get irate about, life is too short, so i'd rather keep out of it.

Michael W

Thread: Electronic ignorance
30/07/2016 11:41:33

Well any kind of useful knowledge has always had the ball and chain of jargon and confusion, sometimes unintended and sometimes deliberated.

I read "success in electronics, Tom duncan" ISBN 9780-719-572-050

I'll kinda summarize here, 

There are questions on each section you can answer, It provides a basic understand of the principles related to electronics, practical applications and real products are picked apart to help you relate to real life scenarios and usage of electronics in action as it were.

Maths requirements are minimal and it's also pretty handy if you're considering taking an educational course on the entry level of electronics. It's been updated here and there to try and keep pace with the rapid developments in digital and fully integrated systems. 

Michael W

 

Edited By Michael Walters on 30/07/2016 11:48:48

Thread: Polishing Brass - or where to get P5000 paper
30/07/2016 10:58:41

I'd use some flour paper and then maybe a little bit of brasso, Incidentally, if you want to get a good finish with aluminium or stainless go for PEEK paste, works really well, slight ammonia smell to it though.

Michael W

Thread: lathe tool sizes
29/07/2016 19:52:39

I think logic would be that you should aim to own a good range of small tools for internal turning and thread cutting, and with external turning you can afford to go a little bigger, but it doesn't really matter alot if you're only taking small cuts, obviously a bigger tool normally means a bigger cutting face.

I find that the "general use size" for me is around 3/8" maybe 1/2" tool steel on some occasions, i know other production workshops where the same rule applies. I have never had a use for a tool any bigger than 16mm square. ever. 1" square is simply ludicrous, it isn't necessary for all but the most titanic of lathes. 

Michael W

Edited By Michael Walters on 29/07/2016 19:57:47

Thread: Pair Of Mystery Tools? Info please.
29/07/2016 14:33:51
Posted by Steven Vine on 29/07/2016 11:52:15:

I see you have one of those new rulers, that redefines the inch. You'll be out by nearly 5mm using that to convert 12 inches.smiley

Yes, definitely not kosher to call an inch 25mm, even if you're at 2 inches you're closer to 51 than you are to 50. It was hardly worth bothering with the lettering.

Michael W

29/07/2016 09:55:37

Can anyone tell what kind of steel has been used?

Michael W

Thread: DECENT DRO
26/07/2016 19:22:36

Well considering a hairs breadth is about 30 microns and a globule of cigarette smoke is around 10-15 microns you'd need to either be eating an awful lot of carrots or came straight out of a comic book.

Michael W

Thread: Files- best bang per buck
26/07/2016 18:27:09

How intriguing, I look forward to it.

Michael W

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