Member postings for CHAS LIPSCOMBE

The question of using an oven or not probably relates to "stoving enamels" versus "air drying enamels" rather than to any of the more recent paint systems. The more modern systems (acrylics,polyurethanes etc etc) may or may not require stoving depending on their exact chemical composition.Usually the temperature required is significantly lower than that used for stoving enamels.

The common-or-garden enamels that have been around for years can require air drying or stoving depending again on their chemical composition. The obvious thing to do is to read the label to see which you have.

It is not technically possible to force-dry an air drying enamel in an oven and reach the higher performance of a stoving grade enamel.A stoving enamel will not air dry, no matter how long it is left to dry.

Similarly the performance charachteristics of a stoving enamal depend on the time and temperature of the stoving stage - again read the label on the tin!

Oldiron, I think the picture of the Roman galley is a bit romanticised. As far as I know the rowers were all slaves, chained in place and never left their positions until death. They ate, slept and defaecated in situ - bad luck if you were on the bottom row of a 3-row trireme.

Chas

Thanks Bazyle!

Fascinating and no day is wasted when I learn something! The quality of this mans work is significantly better than I would have expected from such a crude-sounding method. He casts mainly in nickle silver.

Chas

Neil,

Well......Yes and No. Silicone moulds are loved by the jewellery industry, largely because they permit complicated and undercut designs. They are also significantly cheaper than Aluminium/Epoxy moulds. In an engineering situation they do not last as long as Aluminium/Epoxy. Also because they are prone to flexing during the wax injection stage they usually can't give the same degree of accuracy.

So we can't get away from what we have said before, it's all a matter of horses for courses i.e. how many of an item you need, what degree of precision and cost. For most hobby applications silicone moulds would be perfectly satisfactory, but some foundries will not accept them because they inject the wax under high pressure in automated systems. This causes the moulds to flex at the injection point.

I would expect that a foundry that specialised in jewellery would be smallish and use manual (?) charging of the wax. The cynic in me suggests they don't mind long cycle times because the jewellery trade can accomodate some fairly exotic prices

I have recently come across someone who does lost wax casting of jewellery in a system that uses crushed sea-shells but I don't know any details. Anyone here that can enlighten us?

Chas

Lee Webster,

Your technique of filling a 3D shell is illustrative of how versatile 3D printing can be. It would work well for sand casting but not for lost wax process because the filler would not melt out of the "wax" casting,

As Bazyle says above, the 3D prints must be smoothed for best results - all very well for 2 or 3 prints but a considerable pain if you need to fettle 20-30 prints. I do find that I never get the same quality of product using 3D prints as I get from Silicone or aluminium/epoxy moulds.

Maybe resin casting will overcome the limitations of FDM printing for my purposes - I await Neil's article with interest and I hope he covers the possibility of making prints for lost wax by the resin process

Chas

Noel Shelley,

PLA is often recommended for 3D printing to produce castings for lost wax. My experience is that this did not work at all well and resulted in a high percentage of spoiled castings. I don't however know if this was due to lack of knowledge on the part of the foundry. Certainly things were much better using MOLDLAY. I could not simply change foundries because there are no foundries here in Australia that will lost wax cast in stainless in the smallish quantities I need.

In my case I make motorcycle parts in stainless steel and I need to get the best finish and detail I possibly can. Otherwise the work involved is prohibitive e.g having to polish out lines resultant from poor 3D prints. Especially when these occour in hard-to-polish areas,

As usual It is all a matter of horses for courses. I don't doubt that the castings shown in Neil's photo are suitable for his requirements but they certainly would not be OK for me.

The comments made by Jason in this post are spot-on correct! The process of 3D prints to lost wax castings has many advantages - you just have to make it work

Chas

The big interest for me is using 3D prints as patterns for lost-wax casting. At this stage I'm finding that FFD prints lack surface finish so a resin printer offers promise - BUT can it produce patterns in a material useful for lost-wax? At the moment I use a material called Moldlay from the USA which seems to give the foundry less trouble than PLA

Chas

Hi Bezzer, Your comment about you prefer 316 or 303 stainless to 304 interests me because I work mostly from stainless castings to make motorcycle control levers. I try to avoid 316 because it is not fun stuff to tap in small diameter threads, requiring plenty of clearance in the hole size. The whole engineering industry in Australia has largely collapsed due to cheap chinese imports so the only readily available grade for castings here seems to be 304. I thought that 303 was more easily machinable and I don't know why 304 seems so popular out here. Can you please outline the reasons for your preference? Thanks, Chas

Some time ago I had a bout of chuck sticking and I was advised to use a copper washer (cut from sheet in my case) between the end of the chuck thread and the spindle face. I also use copper anti-sieze and have had no trouble since. Can anyone suggest why the copper washer would be effective? The chuck gets removed and swapped with a 4J chuck every few days.

Chas

Anyone who sent this motorcycle to scrap or sold bits off it should be publicly castrated for vandalism in my opinion

This is a rare model - a historic survival and should be l,ovingly restored, in my opinion by someone who is an old bike enthusiast. Unfortunately the solicitors and the dealers who "advised" you know nothing of its real value and are talking through their anatomy. Some things are worth more than money. My suggestion is to put it up for auction through a reputable auctioneers who specialise in the sale of old motorcycles e.g. H&H auctions, Cheffins or Bonhams.

Dont make the mistake of "preparing it for auction" it is best left in its original condition. Mike Smith of H&H amongst others would be happy to advise, I'm sure. As JimmieS suggests, it would be a big help to contact the Sunbeam club for their advice about this bike

Chas

Can anyone please tell me what spring brass is? Is it the same thing as half-hard brass? I have to make a clip to go on the high tension pickup of a 1909 Humber motorcycle (Bosch magneto). The pickup is ball-shaped and the clip has to spring over it (and stay there!).

There are obviously other ways of killing this particular cat but I need to accurately reproduce the original 1909 item

Chas

It certainly can be fatal. Years ago a local dental nurse was found dead from it's use. She was rather a quiet girl and quite personable, but was apparently in the habit of sniffing the nitrous oxide when the dentist was not around. As far as I know, nitrous oxide is still used as an anaesthetic by dentists.

I note that one source says that it's regular use causes infertility. Step forward please, Mr Darwin

Chas

I seem to remember that as originally devised, cycle threads had two standards, 26 tpi and 20 tpi but the 20 tpi thread was abandoned in 1935. Despite this the 20 tpi thread was found to be useful by motorcycle manufacturers and continued in use even after WW2.

We can get too precious about this - if the footrest thread is old then there will be some wear which will affect thread dimensions anyway.

A while back Hopper commented that despite carefully defined standard tolerances, sometimes sloppy manufacturing (oriental suppliers?) and worn manufacturing equipment came into play, and theoretical thread forms were not always met in practice. Wear on UNF thread manufacturing equipment would lead to a more rounded crest and root form anyway. Certainly for non-safety related purposes I would use a 7/16 UNF nut on a 7/16 BSC thread

Chas

Can anyone please point me to the MEW article mentioned by Hopper? Thanks, Chas

The discrepancy between what Michael Gilligan has unearthed and the actual use of carbon tetrachloride is due to the fact that carbon tet was not used in dry cleaner shops but was widely used in a non-commercial environment. It used to be sold in the 1950's/60's in bottles with a cloth top arrangement so that it could be rubbed on a grease spot to remove it.

There was a famous case in about 1958/9 of a gas meter reader who had a whole string of housewives who were up for sex - his speciallity was to give them a whiff of carbon tet to induce a sense of euphoria before or during the act ( like glue sniffing). How he suceeded in not killing any of them I do not know. For a variety of reasons carbon tet is a chemical we are better off without.

PAUL KEMP:Dont forget there are people like me who are not subscribers but regular purchasers of the magazine. The reason is pure laziness but my local newsagent stocks it, I see it everytime I go there and it is just too easy to buy a copy on the spot. There must be many like me or the publishers would not bother with retail sales. Even though I am a non-subscriber I make a lot of use of the forum, buy stuff from forum advertisers and have ,hopefully, contributed some forum articles that people have found useful.

Would I pay for the forum if I had to? Good question but as a retiree on the pension, I would have to think about affording a subscription plus a forum fee. I guess then I would have to take out a subscription which would also come into it.

In the spirit of the thread title, how about this:

Seen in our local supermarket: Bottles of "Organic Drinking Water". And no, there were no additives,the only enhancement was by the sales dept of the packager.

It is very unlikely that commercial belt cleaners will contain a UV light inhibitor. Therefore exposure to light, especially direct sunlight will cause them to go soft and dungy in short order. Heat is another factor that will cause degradation.

Reading King Olaf's post, it seems that WD 40 would be excellent for sex too

Cynicism about product names and grades is sometimes well justified. I spent much of my working life at a large international paint manufacturer. Their standard practice was to make a large batch of popular lines, like white interior PVA and then split it. Some went into premium quality cans, some went into plainer cans for the trade market, some went into cans with another company's name on it that was owned by the parent company but had a reputation for cheaper products, and some was sold to any little known manufacturer that wanted it. So four different selling prices for the same batch of paint. Hard luck for anyone that thought by paying more for the premium product would give them a better product. It seems unlikely that some companies that make workshop equipment would hesitate to use similar tactics if they could get away with it. Then there is the question that some countries may work to a totally different standard of ethics to those applied in the UK.