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Member postings for Nigel B

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

Thread: DIY hearth
25/05/2017 09:00:12

My employer is currently making wood fired pizza ovens using a perlite or vermiculite & Portland cement mix. The cured shells have proven to be quite weak, prone to cracking & appear to be hygroscopic - the initial experimental attempts that didn't crack during production have failed after a few firing cycles, possibly due to getting damp during periods of non-use & then heating up too quickly when next used. IIRC he did try adding ground-up oil-absorbent clay granules as a binder at one point, but I think the recent builds have been without. The shell wall for these items is around 40 -50 mm thick. I think he is on Mark 5 or 6 at the moment - the latest "mod" being to tile & grout the outer surface to try & improve rain resistance (earlier versions had several coats of masonary paint). The earlier variations were experiments with the mix to get better consistency after failures either during manufacture or after a few uses. He is using a Belle cement mixer to mix the stuff & allows it several days to dry out before removing the forms & an intial gentle firing.

Don't know if that will help or not - but may point towards having to experiment with mixes etc. to get an acceptable result.

Nigel B

Thread: Chucks
24/05/2017 10:15:19

'2 keys', why 2 keys?

Easier / quicker to set with a key in each of the opposing jaws - you can only push with a jaw, so using one key means having to spin the chuck 180 degrees to get to the other side if that is where the push is required. Using 2 keys allows you to push from either side as required without having to rotate the chuck.

Nigel B (another who was taught to use a 4 jaw independant in an apprentice training school)

Thread: The diesel controversy
23/05/2017 08:42:16

They can and do, but they aren't supposed to.

**LINK**

HMG say otherwise - look at the column "Goods vehicles (not more than 7.5 tonnes maximum laden weight)" which shows motorway speed limt as 70 mph. This is the same as "Cars, motorcycles, car-derived vans and dual-purpose vehicles", "Motorhomes or motor caravans (not more than 3.05 tonnes maximum unladen weight)" , "Motorhomes or motor caravans (more than 3.05 tonnes maximum unladen weight)" and "Buses, coaches and minibuses (not more than 12 metres overall length)" - all are 70 mph on motorways.

Dual carriage ways & single carriage ways are another matter, but for motorhomes "not more than 3.05 tonnes maximum unladen weight" sets the limits, not maximum permitted weight.

Nigel B

23/05/2017 07:26:38

Once done you can drive at 70mph on the motorway, instead of 60.

Vans can drive at 70 mph on motorways anyway, so no change there ?

Nigel B

Thread: Engineers blue alternatives
19/05/2017 14:12:37

Or Cromwell Industrial Supplies if there is one near you

**LINK**

Thread: Truing up chucks
18/05/2017 19:39:40

Of course there must be many exceptions, but to me the need for a fitter either indicates small-run production or a firm vulnerable to competition.

I would put many machine tool builders in the "small run" category. Machine tools are not consumer durables like printers in terms of volumes produced & the market is too small to justify the substantial investment required to produce say, a mini lathe or mill in a robotised factory. If Joe Public bought a new mini lathe at Currys every couple of years like they do printers, things may be different !

My former employer was of the opinion that fitters should be unnecessary if the machine shop did their job properly - but also complained about the cost of having parts precision machined. I understand that some volume builders ( Haas springs to mind) do machine to tolerances that require the machines to be "assembled" to the required accuracies from a kit or parts, rather than being "fitted". They do this by using linear guides that bolt-on, rather than require precision fitting like plain bearing machines - which is fine if a linear guide machine does what you want. If it doesn't, then it's back to a "hand fitted" plain bearing machine. They have also invested very heavily in the plant to produce the parts to the required standards.

Michael, fabrications where you suggest would probably cost more than a casting. The 7 series lathes were designed to be mass produced & (initially) sold at a competitive price. I guess that as their volumes declined, they started to believe the hype about the "higher quality than an import" & adjusted the pricing accordingly, rather than investing in more modern methods to produce the same (or better) quality product cheaper. An affordable British lathe - rough edges or not - is not likely anytime soon, I think. Though if you know why it isn't rocket science to do so, please demonstrate how !

Nigel B

18/05/2017 12:53:45

I presume what lathe manufacturers did (or maybe still do) was to temporarily fix the tailstock and head stock body together and bore/ machine all the mating surfaces at the same time. so that everything lines up on the bed.

You presume incorrectly, Michael.

Parts are made indvidually to tolerances & then "adjusted" on assembly to the required accuracy - that is what machine tool fitters are for !

Nigel B

Thread: Aircraft General Discussion
18/05/2017 12:38:04

3/4 scale ?

1:1 scale - the real thing.

**LINK**

Thread: Doncaster show
13/05/2017 15:35:38

I Agree regarding comments about Doncaster being better than Harrogate.

Maybe better than Harrogate as you remember it from the last ME Show, but not now after it has been redeveloped. I was there last weekend for the Northern Shooting Show & can see why the cost of hiring the venue has increased - the replacement for the rather dingy hall that used to house the model boat pond & most club stands is bright, airy & about 4 times the size it used to be. And there is another cafe at the far end of the new hall as well as the "between the halls" original, as well as extensive outdoor catering on a piazza that I don't recall being there before. Still no easier to get in though - 2 mile que at 8.15 for a show that opened the doors at 8.30.

After seeing the exhibitor list for Doncaster, I chose the NSS instead this year - maybe reconsider next year, depending on who (trade-wise) can be enticed to attend.

Nigel B

Thread: The diesel controversy
10/05/2017 11:41:57

the emission test passed no problems

The MoT test for diesels is a visible smoke test, not "emissions" such as Nitrogen Dioxide. I am pretty sure I have seen something about proper emissions tests being developed for MoTs, as the current test is acknowledged as being inadequate. As well as being illegal, tampering with emissions control equipment is downright antisocial IMO.

The "problem" of older diesels will work it's way out in reasonably short order due to attrition. Euro 4 limits came in in Jan 2005 & Euro 5 in Sept 2009 - I pass a vehicle breakers on my way home & most cars there are post 2000 (many post 2004), so it won't be long before many of the Euro 4 cars are getting recycled naturally. The costs of basic repairs are such that even a relatively minor failure in a 10+ year old car makes it unviable to repair - even if you can get the parts. I have shifted 2 out of my last 3 cars because of actual or potential repair costs, the last being a 5 1/2 year old Toyota Avensis with 85000 showing that was eating money. It had 1 front wheel bearing under the 5 year warranty (just within & done with bad grace), another front bearing failed 3 months later & Toyota wanted £500 to replace it (Independant did it for £275). A rear bearing was noisy 2 months later + the CVT gearbox ws getting noisy & Toyota didn't supply parts, only a brand new gearbox for £4500 ! I got £4500 in P/X for another car instead - pointless pumping money into an older car.

The bigger problem with older diesels would appear to be busses, taxis & large commercial vehicles, which have a much longer operating life than cars and light commercials. Legislation to mandate retrofitting of emission control equipment or re-engining with compliant equipment of these vehicles would appear to me to be a more sensible option if faster air quality improvement results are required than car scrappage schemes would provide.

Nigel B

Thread: warco lathes.
09/05/2017 11:33:20

Various Colchester Student 1800s, Chipmaster, Triumph 2000 + Harrison M300s at this auction, ending this week **LINK**

Nigel B

Thread: Alternative to PC based Cnc controllers
12/04/2017 07:39:51

I thought that I could mount it inside the machine main casting / body to keep the noise down

Not a good plan to put an air cooled compressor in a small enclosed space, or to introduce a heat source within the carcass of a machine tool.

Nigel B

11/04/2017 19:17:40

Power drawbars, and presumably the gear selectors, tend to be transitory. They don't need continuous air flow at pressure to work. Provided there's enough capacity to operate once it comes down to how often you're going to be tool or speed range changing. Probably not that frequently.

Indeed. But oil-free compressors don't take kindly to this application - been there & killed a Wolf unit with a 25 l receiver in a very short period doing just this. Killed two of them, actually - the first one was replaced when it died, as it was presumed faulty. I was working part time for the company at this point & the first one came & went while I wasn't there. I read the booklet that came with the second unit & found it had a 15 minutes in an hour duty cycle. Unfortunately this enlightenmant came just as the second unit turned it's toes up. OIl-free compressors are OK for very light use, infequently, or they die young.

Nigel B

11/04/2017 17:56:53

found that the mythical "suitcase compressor" was finally in stock at Lidl as of yesterday. Clouds and silver linings etc. So now I have a means of operating the power drawbar and gear selection solenoids. The CNC gods smiled on me again.

Not with that compressor they havn't. Have you read the specs ? - 1.5 minutes operation, then 8.5 minutes rest to cool down ! No receiver. "Hearing protection required" This maybe OK for the occasional tyre top up, or football inflation, but it won't run a machine tool & survive very long.

The vee twin compressors on a 50 litre receiver that Aldi did recently would be more like it - you would still be deaf when it ran, but at least the receiver would keep the machine operating between deafening bursts to top it up. And, being a wet sump compressor, it is continuously rated. Unfortunately it also cost £100 more !

Retrofit looking good.

Nigel B

Thread: Bronze, Phosphor Bronze, Cast Iron or Graphite for LTD Stirling bearing
11/04/2017 09:58:28

The graphite we machine is man made from, as I understand it, a mixture of coke and pitch. The coke is ground to specific grain sizes according to the grade of graphite required. Other compounds may also be added, like iron filings or sulphur to vary the properties. The resultant thick paste is either extruded or isostatically pressed into blanks, then baked to form a carbon block. The carbon blocks are stacked, covered in deep layer of coke, then heated to very high temperture by passing an electric current through the stack - this converts the carbon to graphite. Improperly graphitised blocks have a higher resistance & are harder to machine & I understand that the graphitisation process is "one chance" process - if it is not done properly first time around it can't be re-visited..

The properties of the blocks vary depending on the mix & how it is processed - some are soft enough to be able to take chunks out with a teaspoon, while others are almost like ceramic & can only be worked with diamond tools - with many variations in between. My understanding is that these man made graphites are different to the natural deposits that are used for graphite lubricating powders - but my understanding may be flawed. When we are asked to supply graphite powders, these come from different suppliers & are physically different to the talc-fine dust that comes out of our dust extractors from machining extruded & isostatic blocks.

Nigel B

11/04/2017 07:50:16

I work for a specialist graphite machining company. so see the stuff (in various grades - and there are many, with widely differing properties) being machine daily. Most grades are easy enough to machine with normal metalworking tools - HSS, carbide inserts etc. For short run special profiles, form tools made from silver steel & gauge plate used unhardened also work. It is abrasive to the tools - a bit like cast iron. It is also very dirty, but (according to HSE investigations conducted at my employer's previous company), poses no particular health hazards and, in particular, poses no explosion risk as airborn dust as it requires the continous application of heat to cause it to burn. Motor brushes are mainly carbon IIRC, not graphite (we don't make motor brushes).

If you PM me the dimensions of the billet you require, I will see if I can get you a suitable piece of fine grained Isostatic graphite from the oddments bin. My employer is usually OK with this & only requires that photos or videoes of the finished item / machine are sent so he has the option of using them for publicity purposes. This grade machines to a good finish & parts can be made to close tolerances (we hold sizes to better than 0.01mm) - it is a bit dirty, mind !

Nigel B

Thread: Is it ok the hold a small lathe chuck in a larger one
07/04/2017 21:06:12

You could put the whole of a Super Adept in an 8" 4 jaw

To turn it into something useful ?

Nigel B

Thread: Boxford BUD restore
07/04/2017 15:04:21

I would be inclined to remove the spindle to clean out any old, hardened, grease from the bearings, check the gearing for damage (missing teeth from locking the spindle with the back gear to remove a stuck chuck are common), then re-grease and reset the bearing pre-load. The mid-60s CUD I inherited from my father had grease in the bearings, nipples & drillings that was the consistency of candle wax & took quite a bit of shifting. There is also a good chance that the back gear shaft will have been greased rather than oiled at some point, so that would also benefit from a good clean out & correct re-lube. Same goes for the saddle - anything with an oil nipple could well have been (incorrectly) greased.

Colour ? Your choice, but lighter colours make for a lighter workshop & something really "off the wall" could have an adverse effect on future resale value.

Good luck in your endeavours,

Nigel B

Thread: Is it ok the hold a small lathe chuck in a larger one
07/04/2017 10:06:40

The turners at work regularly hold a small 4 jaw in the normal, larger, 3 jaw as it is easier than swapping chucks.

Nigel B

Thread: Source for pneumatic fittings?
31/03/2017 15:22:49

Haha, sky hook, tartan paint...

Bucket of sparks for the grinder, a gallon of 10 thou backlash oil ("we havn't got any 10 thou in stock - go back & see if 2 gallons of 5 thou oil will do " etc. etc.

Nigel B

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