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Member postings for Nicholas Farr

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

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Thread: Specifications for 3 1/2" Gauge
13/11/2011 21:55:10
Hi Neil, not my colour, but I can't see any problem with the carpet. Neat work on your chassis BTW.
 
Regards Nick.
Thread: Milling from a sheet
09/11/2011 22:08:51
Hi, (also sorry to digress) but after reading the posts about the "Goscut" I just had to go and find mine, which was originally my late farthers. My one has the last blade that I used in it some, can't remember, long time ago, the other two blades are somewhere in an old toolbox, no doubt. The first picture below shows it in action cutting a piece of 0.4 mm shim steel, and the secound with the piece of shim steel cut in two, with the resultant curl of steel that Clive mentioned. I agree with Clive that they were a bit hard on your hand if used for any lenth of time, but they were revolutionary when they first appeared for the DIY'er.
 
 
Regards Nick.
Thread: Help!
05/11/2011 22:55:33
Hi Mike, you may wish to find some yellow paint for your tray, below is a picture from one of Warco's older brochure's
 

Regards Nick.
Thread: Help
05/11/2011 11:07:30
Hi Wolfie, agree with the others, that crackling sound means imminent drill breakage, so retracting the drill bit before you hear that sound, the better. The deeper you drill a hole, the more often you need to retract the drill bit to clear the swarf, and if you retract it swiftly the more swarf will be cleared.
 
Regards Nick
Thread: How NOT to tap a hole
05/11/2011 10:54:51
Hi Bob, have to agree with Jason. Air impact wrench's very often have a four position torque setting fitted to them, thus allowing some control of power, and they can have the air pressure feeding them reduced which will reduce the speed and torque.
 
Norman I can't see any problem with the use of his vice, as it has a large footprint compared to its hieght, so its unlikely to topple or roll off during the opperations he was showing.
 
Regards Nick.
Thread: Small Steel Boilers
01/11/2011 22:21:16
Hi Dick, magnetite is a black mineral of iron oxide, Fe3O4 often occurring with titanium or magnesium, and an important ore of iron. A magnetically polarised piece of this mineral is called a lodestone. Well that's the way my dictionary describes it.
 
Many years ago the company I used to work for, used to add a portion of it into the mix when making resin coated foundry sand. It looked a bit like black sand, but was quite heavy for its volume, I believe it used to be mined in Russia. It would react near a magnet in just the same way as iron fillings do, but more dense, but the magnetic flux was clearly visable. Never knew why it was added to the sand, but before they used that, they used mill scale, and after magnetite was either too pricey or unavailable, they used some other stuff of a similar nature but I can't remember what that was.
 
I don't think it is the same as the oxide you get on hot rolled steel.
 
Regards Nick.
Thread: Have you recently submitted an article?
31/10/2011 21:33:04
Hi, I'm also with Neil and wish David all the best and help he needs, but also that everyone should backup and support Diane with her efforts, and be patient as well.
 
Regards Nick.
 
 
Thread: 1in Henry Greenley 1930's
29/10/2011 10:01:43
Hi, Maurice is correct, the series by Mr. Steel started in issue 2955 9th Jan 1958 vol118 and then continued in every other issue, with the exception of the Diamond Jubilee issue 2971 1st May 1958 and concluded in issue 2981 10th July 1958 vol119.
 
Regards Nick

Edited By Nicholas Farr on 29/10/2011 10:13:59

Thread: Distortion off BMS
23/10/2011 23:52:41
Hi chris, the annealing process consists of; heating, in the case of steel, to a temperature of 40 degrees C above its upper tranformation temperature, according to carbon content. Holding it at this temperature long enough for the carbon to distribute itself throughout the formed austenite, as a rule the component is held at this determined temperature for 1 hour per 25 mm of thickness. Then allow the component to cool slowly, either in the furnace or in hot ashes or lime.
 
Normalizing is heating to a temperature of 40 degrees above its upper transformation temperature, according to the composition of the steel, holding at this temperature just long enough to heat the component right through, and allowing it to cool in still air.
 
Stress relieving consists of heating the steel to a temperature of 550 to 650 degrees C and holding at this temperature long enough for the whole of the coponemt to reach this temperature, then allowing it to cool in still air.
 
Hope this makes it clearer for you.
 
Regards Nick.
Thread: Drawing Quality
23/10/2011 22:47:28
Hi, I don't know what fag pakets are like now, but there used to be plenty of room on the inside, but you had to chain smoke or give everyone a fag so you could turn them inside out to use them.
 
regards Nick.
Thread: hardening and tempering
23/10/2011 19:06:37
Hi John, as far as I'm aware, carbon steel has to be in the Austenite condition to be able to be hardened, that is from around 700 to 900 plus degrees C depending on carbon content percentage, red hot range.
 
Regards Nick.

Edited By Nicholas Farr on 23/10/2011 19:08:24

Thread: Distortion off BMS
23/10/2011 18:42:57
Hi, I agree with Jason to a point, as the term is known as strain hardening.
 
Recrystallization and Grain Growth
Crystal deformation can have a marked effect upon the mechanical properties of a metal. For instance, when a metal is being rolled in its cold state the crystals of that metal will become greatly elongated in the same direction as the cold working.
 
The crystalline structure will now be of a fibrous nature and strain hardening of the metal will become evident.
 
This undesirable structure can be greatly moified by the application of sufficient heat to produce a new growth of equi-axed crystal grains within the cold worked metal.
 
The temperature at which this takes place is known as the recrystallation temperature and when the metal has cooled down to normal temperature its new structure will be unstrained and the metal will now have regained those properties it had before cold working took place.
 
It is quite likely that an improvment in the metal's properties may now be indicated due to a refinment of the crystal grains, provided grain growth has not been allowed to take place.
 
Grain Growth
The occurance of grain growth, however, can be due to the excessive heating of a metal to a temperature well above its recrystallization point, thus bringing into being a very coarse granular structure similar to that associated with overheated steel.
 
Grain gowth can also be due to too slow a cooling rate after recrystallization has taken place. It is, therefore, always very important to hold the metal at its recrystallation temperature just long enough to allow the new grain structure to form, and then to control the rate of cooling so that this structure will be one of refined equi-axed crystals.
 
Enlarged Crystal grains will cause a decrease in the ductility and the tensile strength of a metal; but these properties will be enhanced when normal grain size has once again been restored by recrystallization.
 
Steel suffers from grain growth at tempertures above 950 degrees C (above transition teperature)
 
Regards Nick.

Edited By Nicholas Farr on 23/10/2011 18:49:27

Thread: Silver or Stainless?
21/10/2011 20:11:22
Posted by Robin Woodward on 20/10/2011 10:20:17:
Hi All,
 
Nick just took me back to 1970........................................................
 
 
I vaguely remember the terms "Face Centre Cubic" and "Body Centre Cubic" as regards where the atoms are and this may have something to do with the strength of the Magnetic forces, I am sure there are some who have a better grasp of the theory than I do after 40 years who can answer this.
 
Rob
 
Hi Rob, you are thinking of the Allotropy of Iron in which;
at room temperature ferrite has a "body centered cubic" structure and is magnetic, and will only take 0.006% carbon into solution.
 
If the Iron is heated above 720 to 920 degrees C (according to carbon content) it's structure changes to "face centered cubic" and it becomes non magnetic and will take carbon into solution. The name given to iron in this changed state is Austenite.
 
Regards Nick.
Thread: Scriber
20/10/2011 06:48:39
Hi Wolfie, basically no. Mild steel will not harden when quenched, but will case harden using a compound containing carbon. Most stainless steels will not harden when quenched either, you would need a martensitic stainless steel, and unless you happen to have some for nothing, it would be cheaper to buy a commercially made scriber. As has been said, Silver steel will be more suitable, or some of the other options mentioned.
 
Regards Nick.
Thread: Silver or Stainless?
18/10/2011 20:55:21
Posted by Wolfie on 18/10/2011 13:17:52:
As a matter of interest, why is stainless non-magnetic surely it has plenty of iron in it??
Hi Wolfie, to understand this fully, you would have to learn a bit of metallurgy. Below is a graph of carbon steels, the temperature on the left and the carbon content at the bottom. The graph shows the metallurgical state that cabon steels are in against temperature.

The next bit is a reply I made in the "Chronos Silver Steel, water or oil quench" thread.
 
Sam, I believe you are describing the allotropy of Iron.
I had to dig out my college notes from 1977 for this one.
Iron can exist in two forms, Ferrite and Austenite. On cooling, it is in its Austenite form at temperatures above the upper transformation line (695 to 920 degrees C)
As cooling continues through the transformation zone (between upper and lower lines) the Austenite changes to Ferrite. During this change Carbon is precipitated from the Austenite, because Carbon is insoluble in (Iron) Ferrite. The precipitated Carbon is in the form of Cementite which goes to form Pearlite, or in the case of steels with over 0.83% Carbon the excess cementite remains on the grain boundries.
Time is needed for these changes to take place. A slow cool will enable the changes to take place and will result in a large grain structure. A faster cool will result in a smaller grain structure.
However, if the cooling rate through the transition range is increased sufficently (i.e. quench) time will not be allowed for the changes from Austenite to Ferrite to take place. In this case there is insufficient time for the Carbon to be precipitated out of solution and this result in the Carbon atoms being forcibly locked in the Ferrite structure. This may be described as a super saturated solid solution of Carbon in Ferrite Iron.
Due to the distortion caused by the Carbon, the grains are acicular (needle like) and are very hard and brittle. The name of this structure is Martensite.
 
As I said earlyer, only Austenitic stainless steels are non magnetic, and this is because there is sufficient Nickel, Nickel and Chromeium or Manganese, to maintain the structure of Austenite.
 
Hope this helps.
 
Regards Nick.
Thread: midlands model exhibition
18/10/2011 18:54:17
Hi Mick, Jason is correct, 1/16th from Reeves.
 
PS. hi Jason thanks for the link to the photos, especially of those of the ones outside which I somehow didn't get round to look at. But the Meccano Wild Mouse display is one I meant to take a picture of when it was a little less busy, but forgot, I though it very impressive.
 
Regards Nick.

Edited By Nicholas Farr on 18/10/2011 19:26:20

17/10/2011 21:00:43
Hi, I also went on Friday, had an enjoyable day, and watched a casting demo, the guy who did that made his furnace from and domestic spin dryer and other bits and bobs from domestic appliances. Got most of the things I was after and as an extra, even bought castings for a little model engine with my namesake that was used on Savages Organs which accopanied their fairground Gallopers, don't know when I'll get round to machining them up though. Didn't manage to see the taction engines in steam though. My round trip was about 240 miles, and I think it was worth it.
 
Regards Nick
Thread: Electric motor on my Tom Senior Vertical Head
16/10/2011 15:43:20
Hi Len, cars are very often like that as well. I guess you have probably had some insulation breaking down inside the motor windings for some time without any noticeable difference, but today those enthusiastic little electrons finally made their breakthrough and spoilt your day.
 
Sorry to hear of your dilemma.
 
Regards Nick.
Thread: Posting pics
15/10/2011 22:15:30
Hi Charlie, yes your photos are visable.
 
Regards Nick.
Thread: Screw cutting gears
15/10/2011 20:13:00
Hi Andy, I believe Norman's yellow arrow is pointing to the correct gear to replace, the other three you can see are never normally removed on most lathes with this type of arrangement.
 
Regards Nick.
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