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Member postings for wotsit

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

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Thread: What exhibition?
12/09/2011 21:06:57
Hi, Goran,
 
I have the same problem as you - not even any modellers in Romania. I know you said shows in England, but if you get the chance, go to the show in Karlsruhe, Germany between 12 to 15th January - this used to be held in SInsheim, then moved to Karlsruhe - way better than any of the English shows. (IMO)
Thread: Hacksaw blade tension
12/09/2011 20:59:27
I was always told to tighten them up till they broke, then back off the tension nut by half a turn........

What is the thinking behind slacking off after use?

Mike - I can buy stiff hacksaw blades in Romania, but they are totally useless (or my technique is suspect!) - the metal seems to be so hard, that 'any' misalignment results in a small chunk of the blade breaking out, rendering it useless. It seems very difficult these days to find good blades which will last - there seem to be many useless things offered for sale which simply will not cut anything. The best I have found in recent years are the bi-metal type, (usually sold singly at exorbitant prices), so I tend to stick to my bandsaw - I can (oddly) still get good blades for that.
 
 
Thread: Darracq
12/09/2011 20:43:43
Hi, Anny,
 
I cannot help you directly with info for your Darracq, but maybe some advice. I also have Richard Blizzards book - a friend wanted a model truck for his kids that wasn't made from plastic, so I built him the Scania truck in Richards book. This led to other things - I built Richards Landrover, but didn't like it much, so designed my own. I found many pictures on the Internet, and enlarged these and scaled them to get dimensions - once I found a good picture, it wasn't too hard.
 
It all got a bit out of hand - I am forbidden to build any more of these wooden models because there is no room for them in our house. I have posted some pictures in my album on this site - the SS100 is the latest, about 30cms long - it has wire spoked wheels, working steering, and the bonnet and hood can be opened/closed - I got the dimensions for this from a small metal model I was given. It is not 100% accurate, but makes a great model.
 
The bulldozer was built the same way. (I asked if this was of interest to ME, but was turned down - apparently wooden models, even if they 'work' are not 'engineering', and other editors didn't even have the grace to reply to e-mails).
 
The helicopter was one of two built for another friends kids, also from Internet pictures. I simply look for a photo taken directly from the side, and also hopefully from the front or side, then use a graphics program on my computer to scale them up or down. I can then derive sizes of wheels and other parts of the car - at least close enough for a reasonably accurate model, as I hope my photos show.
 
If you are going to do more of these models, there is also a book called 'Building Antique Model Cars in Wood' by WIlliam Reeves (ISBN 1-895569-51-6. It has drawings and instructions for several antique cars (unfortunately not the Darracq). The finished sizes are a little smaller than Richard Blizzards models, but they can always be scaled.
 
It would be good to see a picture of the Rolls if you can post one.
Thread: RC engines of the future
25/08/2011 21:34:14
This guy seems to like them - lots of info - even a jet powered go-kart
 
Thread: digital tv switchover
22/08/2011 13:57:17
HI, Dick,
 
Re your comments about interferometry - the idea was considered, but then I realised that due to the abysmal material on most TV channels, there was no justification in using my rapidly diminishing time even considering such a system. I suspect there would be a problem achieving sufficiently wide bandwidth to cover all the channels required, but I can't be bothered to follow it up
 
I put up with what I can get now for the limited time I waste watching TV - I have far more interesting things to do.
 
I don't mind posting information to help others, but I don't want to waste my time - back to the workshop .
 

21/08/2011 12:43:11
Well Said, Peter, I support your comments whole-heartedly.
 
I have made a couple of long posts to this thread, in an attempt to try and help - some of my comments were made to help people to avoid paying out unnecessarily for some of the rip-offs that have (are) happening in this business.
 
Easily the biggest con is to be asked to pay extra for 'digital' equipment, notably LNBs. I am still using two expensive low-noise LNBs which were bought some years ago in the days of analogue satellite systems - both are used (successfully) in digital systems now. The fact is that the receiver paths are still the same - what is different is the signal encoding, which IS now digital, so a different 'set-top box' (decoder) is needed, but the crooks try to apply 'Digital' to everything to try and can more money out of the unknowing customer. I can only recommend anyone wanting to fit a modern system to use the Internet as much as possible, (even OT threads like this!) to try and understand what is needed, or try and find an expert for advice (not the clowns who sell them in the highstreet shop)
 
One comment I would make, and I will admit I could be wrong on this because I do not live in the UK, but I believe that in some cases, it is necessary to fit new terrestrial antennas for digital reception in some areas, due to change of transmitting site and signal levels, as Peter notes, but even this may not always be necessary - simple re-alignment of the antenna may work. I am sure many people can remember the days of messing about with old bits of coat hanger and 'rabbits-ears' to get a picture - often a good one. (but its no good for digital work!) Peter is right - don't believe everything the salesman tells you.
 
I also, like Peter, am no longer in this business, but I worked for many years in satellite related communications, starting in 1967 (yes, so long ago), and have worked on design, installation and commissioning of several Intelsat and Eutelsat geostationary satellite stations (originally over 30 metres diameter), and more recently in active satellite tracking stations. Bit different from domestic TV, but the principles are the same.
 
It strikes me that this thread is attracting a lot of business - despite the moderator trying to delete it early on - maybe it shows just how widespread the interests of a model engineer can be Someone suggested a thread for general (not ME related?) chat - has the moderator an opinion (to try and get people back on his side)?
 
 spelling errors corrected.

Edited By wotsit on 21/08/2011 12:44:07

21/08/2011 08:48:19
To Richard Parsons,

Sorry this posting is a bit late. I note you are thinking about getting a 2 metre antenna to try and get BBC/ITV in Hungary. I am afraid you will be wasting your time. The channels you need are carried on the ASTRA 2 series. I posted a link somewhere in this thread showing the antenna footprints for these birds. The footprint for the ASTRA 2D bird is 'tailored' so it generally covers only the UK and Ireland at reasonable signal strength. The signal strength in Eastern Europe is too low to be useable from 2D . (However I used to be able to get a good signal in mid Germany with and 80cm dish, even so).

Just for the laugh, I obtained a 2.4 metre antenna (in Romania) - but cannot receive a useable signal for the BBC/ITV Freeview channels using a good low-noise LNB. Maybe when I have time I will sit and calculate the gain and size of antenna needed.
 
However, Eurobird 1 is in the same orbital slot, and carries several other free English Language channels, and this can be received with a good signal using an 80 cm dish and standard gain Sat TV LNB. (Channels such as Horror Channel, Movies for Men, various news channels including BBC and Sky. The reason for this is that the antenna pattern is not directed at a specific area, so the signal level is higher from this bird. I can actually receive about 300+ free-to-air channels, but the vast majority are crap sales channels, soft porn, religion or ethnic channels, but we have about 10 or 12 which are 'watchable' in English language. Another alternative if you speak German is to look at the ASTRA 19 birds - they carry all the German terrestrial channels unscrambled.
 
The gain of any parabolic dish is affected by by its size relative to its frequency (the higher the frequency, the smaller the dish for a given gain), but things like surface defects become significant, and can reduce the gain such that the thing is useless. The channels we are talking about are at approximately 11 or 12 GHz, so have a very short wavelength. (I guess from your comments you are aware of the significance of this). For this reason, I don't think it will be easy or economical to build your own dish and obtain suitable performance. The only other thing which is possible is to use an LNB with as good a noise performance as possible - but this will not compensate for not having sufficient antenna gain, and will be expensive for anything other than the bogstandard sat TV LNBs.
 
The following links, and the two I gave earlier in this thread, have a lot of information if you can interpret it, and may help you to see what you can get in your area.
 
19/08/2011 14:57:49
Seeing the comments to the Moderators deletion of the original postings on this thread, perhaps it is time to define some rules as to what will result in moderation action, and the consequences.
 
I would suggest (as a start) that the only reasons for deletion should be personal abuse, porn content and obvious spam - what do you think?
 
I support the idea of OT material because it is clear that it is welcomed by many people, and there is always the possibility that further interest will be generated by OT ideas and information.


 
 
18/08/2011 21:36:12
Great - so where is the missing content?. A number of members exchanging information of interest to them, until some miserable Blisterer complains, then suddenly it all disappears. Having just spent an hour putting together a detailed reply to try and help someone, it disappears along with all the other material after 5 minutes.

Some days ago I seem to remember some comments in here about a forum being a place to exchange friendly comments and information, then this happens. What is the point of the 'ignore member' facility?
 
Anyone know of any good forums anywhere else where free speech and comment is not deleted with no warning, 'cause that sure aint the case here.?
 
Thread: Tee-slotted cross-slide query
03/08/2011 20:43:38
Hi, John,
 
Sorry about the belated posting - just found time to sit and read the forum.
I have a lathe similar to the one you describe, bought from RC-Machines in Luxembourg (http://www.rc-machines.com/index.php) - If you are in France, they might be easier to get to, or cheaper than the ridiculous UK postal charges by mail. They used to do second stuff as well, so perhaps a call or e-mail to them might help.
 
Thread: Milling Machine
03/08/2011 20:36:27
Great Thread! I was developing a complex from seeing all those clinically sterile pictures of machining work in progress that are published in ME. I thought I had a serious problem when I found life was too short to spend most of my time sweeping and vacuuming up the swarf, then polishing the machine, treating it with anti-rust oil, wrapping it a warm blanket, singing it songs.....etc, etc. Cleaning the working bits sounds great to me.
Thread: Forming Wire Wheel Rims
28/06/2011 20:48:27
Hi, Tim,
 
I posted a picture of some spoked wheels I made for a model (bottom of home page - sorry they are not in this post - I never could be bothered to work out how to do it in this forum).
They have turned stainless rims (using thickwalled tube) and hubs. The spokes are 'laced' using stainless steel wire (hard work!).
 
I have also made some other spoked wheels using a cast aluminium rim, subsequently turned to shape. These were somewhat easier to turn than the ones in the photo.
 
There is an exhaustive description of making spoked wheels in ME vol 4249 10-23 June 2005) by Stephen Atkinson, as part of his series on building a scale model 1946 MG TC.
 
In my opinion, you will have your work cut out to make rolled metal rims.
Thread: Clarke CL300 Lathe
06/05/2011 20:44:40
Hi, Julie
Just found this:-
 

Keith
06/05/2011 20:20:01
Hi Julie,
 
If you Google 'Mini-Lathe', or '7x10 Lathe' you will find dozens of sites showing mods for these machines - things like fitting ballraces in the cross-slide, tailstock locks, head bearings, tool blocks, fine feed systems, digital readouts and so on - the list is endless.
 
You did not say why you want to modify the motor/belt drive - the actual belt drive is fairly robust - I am still using the same belt after about 9 years of fairly solid use. Incidentally, the belt (at least on my machine) is a reinforced toothed belt. However, the motor and control system is something else. John has documented one version of the motor speed control board pretty well in another thread on this site - the version he describes has a nasty habit of destroying its output devices if the motor is stalled, but they can be repaired. There are later boards which can withstand a stalled motor - so far I have come across four different versions. I am half-way through reverse engineering one of these later ones, but it has a low priority for me at the moment. Note these are not different versions of the same board, but substantially different designs. I think it is probably fair to note that the older board type as described by John in this forum is unlikely to be fitted any longer - the newer 'stall-proof' boards should be in common use by now.
 
If you replace the motor (presumably for a larger one), then first you have the option of DC (as standard) or AC. A bigger DC type will require a new controller board able to handle the bigger motor. An AC type (single phase) is very difficult to speed control (which is a desirable feature of the original machine) - to get good speed control, a three-phase motor is preferred, then a VFD can be used, but this is fairly expensive (probably as much as the original lathe for a good system).
 
The only other way is to use a (single phase) AC motor, and use the traditional method of different size drive pulleys and shift the drive belts - and I think this will be quite difficult to arrange in a reasonable manner on these mini-lathes. The original motor fits in a fairly restricted space, so it is likely that a different motor will need to be mounted on some kind of extension at the rear of the machine - I don't say any of this is impossible or impractical, just deserving of some thought!
 
Maybe you can post again and tell us why you want to do it - that way you should get some useful suggestions.
 
Keith
Thread: Cheap linear scale display
30/04/2011 17:12:34
Take a look here also
 
 
Thread: Steam turbine, which of the design is effective??
23/04/2011 18:41:03
Hi, Jens,
 
There may be some useful information to help you in the following thread on this forum
 
 
Good luck
Keith
Thread: casting small parts
10/03/2011 19:25:33
Hi, Terry,
 
I asked about Borax/washing soda, because borax is used as a cleaning agent. I have, as you say, used it for flux with silver solder, but I wasn't sure if it was the same or a related chemical to sodium carbonate (I'm a total loss at chemistry - sorry)
 
Do you have any idea exactly what iron (and steel) does to aluminium? I know it 'erodes' away in contact with molten aluminium, but as I noted earlier, I have had (apparently) perfectly good castings (no voids, no entrapments) that were prepared in either stainless or iron containers. What I am looking for here is to try and isolate the circumstances under which this happens - I know all the books and info says don't use iron/steel (even stainless), but nonetheless, it does work sometimes. Maybe there is a defect in the casting composition which is not apparent in simple castings with no great stress, but I am still interested in why I can (for example) cast a set of pulleys which are fine, and an hour later, using the same materials, technique and containers, get a casting which is scrap because of the voids and entrapped 'dirt'.
 
Incidentally, just as an experiment, I experimented with making a near liquid mix from local clay (out of our garden!), painted inside my iron crucible. I let it dry overnight, then did a melt in it. Much to my surprise, the clay stayed relatively intact, except where I bashed it when I was skimming the melt. After I had finished it was baked to a hard, dark orange-brown colour - it seems encouraging enough to follow up to see what happens. (but unfortunately, the casting was not too good - lots of pinholes when I cut it open)
 
 Geoff Ball (thanks) also mentions using washing soda, and its preparation for use earlier in this thread, so thats another avenue to try.
 
Thanks for the input - all good stuff - apologies to Richard chuklbutty who started this thread, for inadvertantly hi-jacking it
 
 
 

Edited By Keith Wardill on 10/03/2011 19:30:34

Edited By Keith Wardill on 10/03/2011 19:32:31

10/03/2011 15:04:27
Hi, Michael,
 
I am a little surprised at the difficulty yo have getting the hard foam I described. The difference might be due to the way houses are built in UK. I used to live in Germany, then about 3 years ago moved to Romania. In both countries (in fact, most of Europe),it is commone practise to built new houses with this foam used as a cladding on the outside walls, then covered with a skim coat of waterproof concrete. Certainly in Germany and here in Romania I can walk into any builders or DIY store (we have several large ones near where I live, and buy this stuff in any thickness up to 10cms, either by the sheet or by volume. It comes in different colours, which doesn't seem to have any significance. When it is cut, it is a consistent smooth finish - no apparent 'cells' like you see in the white packing foam. The surface ahs a slightly reflective, almost silky appearance. It is quite hard - it is possible to kneel on it and only leave slight depressions - my missus like to use a piece for kneeling down when weeding.
 
Yo are obviously more knowledgeable abou chemistry than me - I am limited to the 'try it while standing well back' school of thought, but it is useful to know that the swimming pool tablets should work - but its a horribly smelly business! Thanks for the tip about LO Salt - I don't know whether I can get that here, but I'll take a look - I hadn't heard about sodium bicarbonate. I can get big bags of the stuff from the local wholesaler, so maybe I''ll try that when I get time.
Like you, I started off with stainless steel canisters, but as you say, quickly found out that there is stainless steel and steel that looks like stainless. I also had the problem of it quickly virtually desintegrating, so that is why I went to the thick steel tube I mentioned earlier. It was a real pain when the canister leaked whilst in the furnace. I have a piece of stainless tube now, about 10 cms diameter, with walls about 4 mm thick, so I intend to weld a stainless plate to the bottom, and see how that lasts. Apropos the use of stainless - I suspect this does 'pollute' the melt in some way - it does not melt in the temperatures reached with aluminium, but seems to erode away. Assuming the metal goes somewhere , it must end up either as dross, or in the aluminium - any ideas what this will do?
 
I have read somewhere about allout alloying with copper - I experimented with this by dropping small chunks of copper pipe in the melt - they do 'disappear' - they are not left behind in the cannister. I assume the mechanism for this is the same as for stainless (i don't know for sure). I don't know how to go about any scientific testing of this, but the resulting castings did seem to be harder - it turned more like Dural than aluminium. On one occasion, I put quite lot of copper in, and the resulting cast had a distinctly gritty feel when I cam to turn it. I thought it was inclusions, but ther was nothing visible, just an odd feel when turning.

Thanks for the ideas. I'll maybe post again when I have had time to go and play again.
Best Regards,
Keith
Thread: im a beginner but i am in my 80s
10/03/2011 14:43:55
Hi, Martin,
Thanks for the comments - I have aways had an interest in computing, which maybe gave me a head start - I worked on mainframe computers long ago in the past. The first one I ever saw was Atlas at Manchester University, and the first one I worked on was a Elliott 805 (i think it was) back in the early 1960s - this was a serial machine, with a 1kiloword magnetic core store memory, wordlength of 18 bits. It had to be programmed using punched paper tape using Eliott Autocode and output was to a teletype machine. They consisted of a number of cabinets about 1.5 metres tall and a metre wide, and there were 4 or 5 cabinets, depending on the functionality. They were started up using the same type of batteries which were fitted in Concorde - PCs are eezy-peezy after those monsters.
 
So, I can understand the amount of time one can save if computers are used efficiently, hence what was intended to be a gentle dig at the use of only lower case. I guess everyone gets to a point where resolving fine details becomes harder, and in these days of texting mania, I just felt it was time to point out that text written in lower case can be more difficult than need be to understand, particularly when, as did William, trade names are used. Life is too short to waste
Best Regards,
Keith
Thread: casting small parts
09/03/2011 20:51:30
Apologies to Richard for this going OT, but some interesting stuff (to me) has come up.
 
Michael: - I have used the white packing foam in the early days, but I wouldn't really use it now - you are right that it seems to produce a very rough casting, and I had some problem with deformation, which seemed to happen during the pour. This took the form of apparent 'bulges' in the casting, as though the pattern had collapsed in a certain area. I have no explanation for this, but it has never happened with the 'hard foam' - incidentally, it comes in all colours, and I usually get mine at a builders merchant, its very cheap, and can be bought in single sheets up to about 1metre x 60cms, and up to 10cms thick - avoids the postal costs and delay on eBay. (will they send a single sheet through the post?). You can stick it together with a hot glue gun (plastic sticks). The info about the fumes and molten plastic, etc is interesting - I wondered if this was a cause of voids and the inclusions, but I had no way to prove it. Most users seem also to use the latex paint or thin plaster coat technique - I certainly get better castings using it - how would this affect the absorption of the styrene, etc into the sand?
 
Gordon W: This hard foam can be turned and sanded to a very smooth finish. There is usually a fair amount of stink and flames when you pour - really makes your eyes water - don't lean over it when you do a pour.
 
Ian SC and TerryD. I have heard of using Borax as a flux - is this what you mean by washing soda?. Like you, I haven't tried it, but its on the books for a try soon - I bought a big box full. I also have tried salt to prevent gas absorption, but results were a bit indifferent. The salt appeared to melt on top of the metal. I tried skimming it off just before pouring, but still got small pinholes and voids. I also tried leaving it on the metal, and just pouring 'as is', but again the results where indifferent - still some voids and inclusions.
I was told once that the purification tablets used for swimming pools could be used as a flux - may be this is where the floride (?) idea comes from. The tablets have to be plunged into the melt, so it melts and comes up through the metal (so I was told), so I bashed a piece of aluminium tune flat near the end, filled the last few centimetres with crushed swimming pool tablet, and flattened the end of the tube to keep it in place. This tube was then stuck into the melt. (very carefully!). After a few moments, there was a thick cloud of vile-smelling smoke and some bright white flames as the tube melted. I have to report that once again, no real conclusive results.
 
I have had conflicting advice on (over)heating - some say (as IanSC), that it shouldn't be overheated (how do you tell without a pyrometer?). I have read that it should be heated until the metal is running freely (like mercury), then removed from the heat, skimmed, and left to stand for some moments until it develops a 'claret-coloured skin' on the top. It does develop a sort of coating if you do this, but to me it looks more like oxidation. Then what to do? - skim it again? pour it? - what?. And this makes no sense if a gas exclusion material like salt is used - so lots of confusion here.
 
The annoying thing is that on occasion, I have had the 'perfect pour' with no 'remedies' except skimming the dross - the casting is great, no holes, no inclusions and turns up a treat. I have tried reproducing the conditions as best I can (can't control the weather though!), and the next pour is rubbish.

As IanSC comments, I have also read about iron containers, but where I live crucibles don't exist. However, I tried stainless steel canisters - these seemed to work fine, but very quickly develop holes - the metal doesn't melt - it sort of erodes away - and it is dangerous getting hot metal around your feet. Nonetheless, some good pours from it. I have also made steel crucibles from a chunk of steel pipe with a thick plate welded onto the end. These last much better than the stainless steel cans (but will still eventually develop holes). Again it is hard to say whether they affect the pour , sometimes the final casting was great, sometimes a dud.
 
Despite these problems, I still use the technique - it is often much quicker to make a casting than to fabricate a part, and quite often, pinhole voids can be ignored. When I started, I was surprised how easy it was to produce parts, providing you remeber that molten aluminium is dangerous if not handled carefully.
 
Regards, Keith.
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