Member postings for CHAS LIPSCOMBE

From Jason's chart, I see that 1BA is something of an "orphan" thread with no clear alternative. A nuisance because it was used extensively by Amal carburetters for their motorcycle handlebar levers and ealy carbs. Does anyone know of a closer equivalent. than the ones shown in Jason's list?

The choice of method has to depend on the job. Bizibuilder's method will give perfect results at the expense of a lot of time. Use of any kind of polishing mop carries the risk of removing sharp edges, losing detail e.g. lettering (if present) and "dragging" holes. Unless the pressure on the mop is kept light, there is also a risk of getting "drag" marks on the job.It is the usual case of horses for courses, but I would have thought that fine work like clock-making would require the slow method. Clock cases, support pillars would be fine on a polishing mop but clock internals??

John Halfpenny - your technique would obviously work but I'm not sure why you would not put the lid on after using the paint and see if the contents skin over, rather than deliberately allowing skin to form.

NDY - Inverting the can briefly to let paint seal the lid joint is good practice. I should have mentioned this in the first place

Martin King - The solvent used needs to be the same as the solvent used in the paint formula e.g. use the thinners recommended for that product. Air-dry enamels are very likely to be compatible with white spirits but spraying "enamels" will need toluene or just as good is xylene. The recommended thinners for spraying enamels will be compatible with air-dry paints but you need to be cautious to use as little as possible, or you will cut the viscosity to that of water.

In this day and age you might find it difficult to buy Methy Ethyl Ketoxime but then again there are some pretty dangerous chemicals sold on ebay that should never be allowed to get into the hands of unqualified people

JOHN, From what I have been told, molasses is not a common commodity in the UK. However with Britains growing overseas-born population it might be now. On the other hand you might be confusing molasses and treacle which I believe are not the same. I was born and bred in England and prior to covid used to visit regularly. Good to know that all the supermarkets are still there since I last visited 3 years ago.

A very popular rust remover used in the old vehicle restoration hobby in Australia is Molasses. Sounds strange but I and many others have been using it for years and it works really well. Immersion in a solution of molasses in water (concentration does not matter) for a week or so will completely remove rust. I believe that the idea originally comes from America where it is a well-known idea amongst the gun restoring fraternity.

In Australia and the States, Molasses is widely available from the sugar-cane industry and is used in the cattle feed industry. It may be hard to get in the UK. Two possible sources are the Carribean/African food shops and maybe it is available from animal feed suppliers?

I have received much help from various forum members but usually I am not able to contribute much. After a working life on the chemistry side of the paint/plastics industry it is nice to find a subject I can perhaps usefully add to.

For oil-based paint, the usual paint-makers technique is to add a volatile anti-oxidant to the paint at the last moment before canning it off. Methyl Ethyl Ketoxime is the usual one. This additive prevents skinning in the can but it must evapourate quickly from the applied paint film or it will stop the paint from drying on the job.

All well and good, but if the painter has the can open for any length of time, the anti-oxidant will evapourate out of the paint left in the can - result: the remaining paint is going to skin over in the can. The bigger the air space above the paint in the partially empty can, the more pronounced this happening will be.

There are two techniques that can be used to stop this happening:

1. Decant the paint before using it, into a number of small containers, seal them tight and use these in turn. This is the most foolproof method

2. Cover the paint left in the can with something to stop air getting to it. Any of the suggested methods using clear film etc will work fairly well but the use of a solvent layer on top will only work if the paint can will not be moved about much after adding the solvent.

It also helps to be conciencous about cleaning around the lid and can rim to ensure a good seal.

However ONE POPULAR IDEA DOES NOT WORK and that is storing the paint tin upside down. If the conditions are met for skinning are present (i.e. loss of antioxidant, too much air above the paint) then the paint will do its thing and skin. The difference is that the skin will be below the paint when the can is opened. It then becomes very difficult to remove the skin without leaving bits behind that are difficult to remove entirely.

Please note that my comments only apply to oil-based paints

Chas

Let down steel rivets? Can someone please explain this term to me? I thought that steel rivets were made of dead-mild steel which would not harden with age?

When stuck for an alternative, I have made rivets from ordinary woodworking nails - a lot of faffing around but it got the job done.

In difficult assembly situations would it work to hold the bits together with superglue at a few strategic points,then just rivet them together(for appearances sake)?

Chas

David, The 3 light-coloured bricks on top are vermiculite. The base slab is some sort of fire grate brick as I don't have enough vermiculite ones at the moment. . The bored out piece of brick holding the job is also fire brick - same reason. We are in lock down (again) at the moment and I can't find an Aus supplier that will post small numbers of vermiculite brick because of breakage. Someday everything will revert to normal...............I hope.

Keith I really do appreciate the time, patience and effort you put in helping people, including me, on the forum. Especially when my problems this time mostly come under the category of "When all else has failed,read the instructions".

Bill Phinn. As far as I can see with my inexperienced eye, the torch is adequate for this job but I have noted your input and if I'm still in trouble I will have to purchase the kit you recommend. When all else has failed.........!

Dave Halford. That is a good point you raise about the centre of the job being hot enough because stainless is a poor conductor of heat. I don't think it is the problem in this case but it's a point to consider on future jobs

Regards, Chas

herewith photos to go with my previous posting

Somehow I have just lost my long reply to all the good folks who replied to my post. Also no luck in getting photos onto the post - looks like I will have to look through old posts detailing how to add photos. Maybe I need to create an album.

I think my troubles are self-inflicted. I had some cadmium free 45% silver rod (BOC 45T) and some JM Easyflow flux and tried those. I could not get sufficient flow through the joint and I see now that the Easyflow flux is not adequate for this situation.

As Keith rightly says, all the answers are in his book, except that I was not sure about the fit required.

I think my rod will be OK for the job. I have some Tenacity No 5 and will try again after a good clean-up and re-tolerance.

I am using disposable cylinders of "MAP gas replacement" which seem well up to the job ( I seldom have need to silver solder so not worth investing in more expensive equipment). This is my first attempt at soldering stainless steel and screening the job with vermiculite blocks.

Interestingly a google search for Tenacity No 5 does not throw up any results but I can find results for other tenacity grades. Tenacity No 4 is available in Australia but apparently not No 5. Would Tenacity No 4 work or not for stainless?

Will try to send photos later. Chas

I have a need to make 12 stainless steel t-handles with the core stock about 14 mms diameter and the tommy bar itself 8 mms diameter. The core is 12mms long and the tommy bar is 60 mms long, so not a big item. This job has not gone particularly well so far, although Keith Hales book has given me some good pointers.

My queries are 1) Keith suggests a minimum gap for capilliary flow of 0.05 mms but I have no means of measuring such a gap accurately when the hole is only 8 mms diameter. Elsewhere Keith talks of a "Good rattling fit" which is probably common jargon in the UK but unknown to me in Australia. How do our members decide what is a suitable gap? Can someone explain what a "good rattling fit" means?

2) In theory I could use a high strength Loctite but I lack confidence in this because the job is for the filler caps of vintage motorcycles and will be exposed to rain and maybe petrol. If I did use a high strength locktite how tight should the parts be - drive tight, light tap or firm hand push? The material is 304 stainless. Regards, Chas

Sorry to have confused people with my post. Over several years I have experimented with various ideas to obtain good quality castings which require a minimum of finishing when they arrive from the foundry.

Hopefully this explanation will make everything clear (if I am lucky) There are two distinct situations:

1. Lets say I get 30 or so prints delivered from the local guy that does my 3D prints. The purpose of these prints is solely so I can send them to the foundry for casting where they take the place of a conventional wax image. I have an ongoing problem with these prints with layer lines and defects and I get round this by applying a wax to cover the imperfections. This is time consuming and the purpose of my original post was to see if there is any alternative out there, such as an aerosol wax spray that I could use.

2. The second situation is that once I am satisfied that I have got the design right and there is a market for the product, I change from 3D prints to using a permanent mould. To do this I take one of the 3D prints, spray it with automotive spray filler, sand it smooth then send this pattern to the mould maker. The mould maker makes me an aluminium /epoxy mould which then goes to the foundry. The foundry prepare waxes from this mould and carry out the casting as per usual. I get far superior stainless castings by this route.

My experience so far with 3d printing is that it is brilliant for prototype work, allowing easy changes to be made without getting expensive moulds made that turn out to be not quite suitable, but so far I have not been able to get prints of a suitably good quality for volume production.

A further experience is that I have not been successful in using PLA for the 3D prints. This might well be due to lack of expertise by the foundry but I was getting too many incomplete castings. I now get my prints done in MOLDLAY which is, I think, an American product and of undisclosed composition. This gives much better results than PLA.

Jason: Thanks for the tip about wax treatments not being compatible with making the "tree" which is how the foundry do things. I agree that silicone moulds have their own advantages, including cost but the foundry I use won't use them. Sadly there are very few foundries in Australia that will do stainless castings by lost wax and even fewer that will take on small batches like mine.

Chas

Amazing! such a quick response and so many very helpful replies

Jason: I do use exactly the technique you describe, except that the foundry I use will not accept silicone moulds. I have to get Aluminium/Epoxy moulds made. I find 3D printing just about indispensible for prototypes before committing myself to the expense of hard moulds. To avoid confusion what I do is hobby stuff to keep me mentally and physically fit at 81 years old. Any negligeable profit is quickly absorbed by new tool purchases!

Luker: Thanks very much for your reply, is Acetone only useful for ABS or does it work on other print materials? I will look into the silicone spray question but my problem is more the quality of the print surface rather than porosity. I would very much like to see a copy of your article but I don't get ME - any chance I could get a copy of the article from you? The tip of using steel wool sounds interesting!

Paul Lousick: I don't think this would work because the fillers in the primer would probably not be carried out completely with the wax when that is melted and lead to incomplete castings.

Neil: You are quite correct, it's all a question of terminology. As a retired chemist, vapour implies concentrated matter to me while what you describe would be fumes. No matter, your terminology is every bit as good as mine I shall study your link in detail as soon as I finish this post!

Adrian Johnstone: Thanks for your link. Again I will study it in detail as soon as I finish this post. I have seen prints from resin printers and they are truely of amazing quality. However the one I know about use "acrylic resins" which may not be suitable as "waxes", although they would be excellent for making silicone moulds. For me I suspect costs would be prohibitive.

Steve F: I shall certainly investigate this

Bazyle: Unfortunately the foundry are no more co-operative than they need to be but I will try to get them to run a few prints coated with PVA just to see what happens. "Just to see what happens" is the curse of the scientific mind. It can lead one into all sorts of trouble DAHIK. The choice of foundries in Australia is very limited.

Chas

My interest in 3D printing is deliberately limited (so little time, so many potential areas of interest) to buying in 3D prints that are used as “waxes” for lost wax casting in stainless steel. I use the stainless castings to make a range of handlebar levers etc for vintage and veteran motorcycles.

As bought, the prints often have minor defects and visible “layer lines” all of which can result in a failed or poor quality casting. To get round this I go over the castings with a wax product I get from the foundry. I think this is a locally-made product here in Australia and the foundry uses it to repair blow holes etc in conventionally produced wax masters before casting. This process is slow and time consuming and I want to find an alternative.

What I need is a spray-on wax that gives a thickish build on the 3D print, which I can then smooth off to give a good surface to the print.

My question is – can anyone think of such a product, maybe designed for a totally different purpose that would do this job? Aerosols of car polish wax give too thin a build to be of much use.

Some alternatives that I have already looked at are:

1. Print more finely – raises cost per wax significantly
2. Use acetone vapour to smooth the prints – as a retired chemist I view this method as an easy way to die. Good luck to anyone who boils acetone to use the vapour at home, but I have no wish to feature in the Darwin Awards.
3. Methylene chloride brushed on works but only after a fashion and is quite toxic and probably a cancer causative

Chas

Oily Rag:

Thanks for a most interesting post. What are your views on stainless steel spokes? These seem to be popular on motorcycle restorations these days. My motorcycles are all pre-1930 and not massively powered but I still use non-stainless spokes. I don't know what type of steel they are.

Chas

A really interesting set of replies and very helpful. as usual Hopper and S.O.D have come up with common sense answers. Clearly it really doesn't matter a hoot for the miscellaneous small fittings on motorcycles which is what I had in mind. If the application was more demanding e.g. timing shaft nut to secure the timing pinion, then I would be sure to use matching thread forms, just as a precaution.

I really wonder just how accurate thread angles would be on el-cheapo handyman screws from Thailand or China would be anyway?

Chas

Does it make any significant difference in practice (as opposed to theoretical considerations) if a thread is 55 or 60 degrees?

If I mate a 55 degree brass thread nut with a 60 degree CEI bolt, does it really matter?

I'm thinking here of motorcycle type applications, not extreme performance situations.

Chas

A great solution that I will definitely try. My solution is less elegant but so far has worked for me, is that after clearing the nozzle by a quick press with the can inverted (which as Blue Heeler says does not work too well for long-term storage) is to push a fine wire into the spray hole and leave it there until the spray can is used again. I have kept a clapped-out wire brush for use as a fine wire donor.

Chas

Potentially a very interesting topic for me and a way of making floats for very obsolete carburetters. However I live in Australia and have not come across the terms rohacell or nitrophyl before. Can anyone tell me what sort of material these are?

I believe that Indian motorcycles always (?) used a float made from cork or balsa wood, covered in some sort of petrol proof lacquer - does anyone know what this lacquer was?

My knowledge and interest of motorcycles only goes to 1939 (with a special interest in New Imperials) but I thought that Amal monoblocs had nylon floats??

Chas