Member postings for Andrew Tinsley

I have tried another blunt file in dilute phosphoric acid at ambient temperature. It is still reacting very slowly with a little gas release to show that things are happening. I left it outside overnight and the reaction rate had almost ceased, as the day warmed up, then the reaction speeded up. I will let you know the results later.

One WARNING, when the reaction occurs at high temperature, there are copious obnoxious white fumes evolved in great profusion! DO NOT breath them in, ask why I know this!?

Looking at the micrographs that Dave has provided I suspect that the sharpness of the files is due to the very rough structure shown in the last photo. Even so, the files do cut at a rapid rate, but for how long is any ones guess. When I have some need of lots of filing, I will give some feedback on how long the sharpness lasts.

Andrew.

Oh I forgot to say that my experience of, even dilute phosphoric acid, on concrete, is exactly the same as Dave's!!! The slabs on my patio now have some very clean areas! I just hope my wife doesn't notice. Some hope!

Andrew.

P.S. It is very odd that provided the solution is not very hot, I fished out the files by hand, no real sensation of acid on the hands, but do swill them with clean water afterwards.

Hello again,

I tried the etching again, this time with one of my blunt files, of recent vintage. This time I didn't need to change the phosphoric acid. Previous files were so rusty that I believe I had exhausted the acid, because etching stopped even though the mix was quite warm. There was also a huge amount of black sludge on the bottom of the plastic container, plus a very black file after the first two etches.

With the non rusty file, the etching continued until the mixture became cold. Adding more boiling water got the reaction going again. I then realised the reaction rate was very temperature dependent (forgotten my 10 degree chemistry reaction rate rule!). So I used my large ultrasonic bath, which is stainless steel plus a heater. I set the temperature at 80 degrees centigrade. After 2 hours, I fished out the file and it too, was very sharp. There was a very thin layer of black particles at the bottom of the bath.

The file was laid horizontally and no effort was made to lift the file clear of the bottom. I now have 10 very sharp files for the cost of the phosphoric acid used, which is probably around the 50 pence mark. It has worked for me, so I suspect it will work for others. Again, I do not know if the effect will last as long as a new file. But considering the cost of the operation is peanuts, I think it well worth doing, even if the files don't last as long as new ones!

Andrew.

Hello Dave,

You may well be right about the type of steel making a big difference. I treated 9 files and they all came out good, but they were all very old files from the 1950s I would guess, maybe there is something about them that gave me such good results.

Andrew

Hello Neil,

You may well be correct. however there was so much thick rust on the files that de-rusting was a first step! I have heard that some old timers used sulphuric acid to sharpen files (maybe nitric or hydrochloric acid, I am not quite sure!).

I doubt that any other chemical method would give better results, these old files are now incredibly sharp, one stroke on flesh would produce much blood! However I would caution that I have no idea if the files will last well in service. I have yet to find that out. I will let people know the long term results. It could be, that it only works with very rusty files. I will try to find my bluntest file and give that the treatment.

Andrew.

I had quite a few VERY rusty files that I inherited from my father. The rust was so thick, you could barely see the individual teeth! I was about to bin them, when I remembered that I had a 5 litre can of conc phosphoric acid, off Ebay for a very low price. I had used this to de-rust a lot of items.

So I thought why not try the files? I prepared a solution of approximately 20 to 1 boiling water to conc phosphoric acid. In went the files and I was rewarded with much bubbling. Eventually this slowed right down and looking at a file it appeared to be covered with a jet black substance. I assumed that the solution had become too weak and so I then repeated the process. On the third treatment, the files came out just slightly black and I assumed that the rust had gone.

On drying, all looked well and when I tried rubbing my fingers over the file, I found it to have incredibly sharp teeth! More so than a new file. So it was a very worthwhile exercise! I have no idea how the files will fare long term, but filing a piece of mild steel, the removal rate was very high indeed.

Andrew.

Hello Tony,

I don't think you have that correct? "Profuel secondary flame burns twice as hot as acetylene". I believe it is actually about 200 degrees centigrade cooler.

Anyone that has used Profuel and acetylene, can they say what their experience was of the two? One person says they don't notice the difference. On the one occasion that I used it, I was underwhelmed. Maybe I had not got the correct nozzle size, I used the one that I would normally weld with acetylene, maybe there is some difference?

Andrew.

PS, there is a hobbyweld agent very close to me, I will go and chat with them.

Hmm, seems to be a NO as I suspected. I have had oxy acetylene for almost 50 years now and you just cannot beat it. None of the other oxy fuel gas systems comes anywhere near, for the sort of work I do.

It almost seems worth going to France on a day trip, anything is better than £800 rental and now probably in excess of £1000 at next renewal. The BOC B%%%%%%s even charge you a hefty "Handling Fee" even when you pick it up from the depot!

Seems they just want to discourage people like me!

Andrew.

Hello,

If you want a Rohm drill chuck on an MT2 taper. just buy a complete unit from Tracy Tools. They do a range of Rohm chucks on MT tapers and they are cheaper than most, especially if you have to buy the chuck and MT2 taper individually if you want to DIY!

Andrew.

My 5 year contract with BOC will soon expire. Last time I renewed they wanted £800! Some time ago there was a thread about alternatives. It soon got hijacked with mig welding gases.

So is there anyone doing oxy acetylene cylinders, without BOC's rip off prices? I live between Leicester and Peterborough, so a fairly local depot would be nice !

Regards,

Andrew.

Agreed!

Andrew.

Thanks Tony, You seem to have made the job somewhat easier! I suppose it is the usual reluctance to do something new, especially as I thought I may have one shot at getting it correct!

Hopper, thanks for confirming that the bearings are solid white metal, that makes me feel a lot better about doing the job.

The bearings didn't have too much play before dismantling the headstock. There were plenty of shims left , so maybe I could try sorting out the original bearings. It would give me some practice and I still have the new bearings to go at if I make a mess.

I know the history of the lathe from new and the bearings have not been touched since they were installed at Myfords. Now here is an oddity, the shims under the cap nearest the chuck are all the same thickness EXCEPT for the one at front right, which is 7 thou thinner than the others. There is a piece of solid shim (cut exactly to the Myford pattern) the rest being laminated shim. I am somewhat amazed by this. It has been executed very neatly. I can only think that the original bearing must have been distorted during casting, although this seems very unlikely. Anyone care to guess what the reason is for this oddity?

Thanks,

Andrew.

I didn't realise that Arc Eurotrade sold the wedge type at such good prices. Otherwise I may well have purchased them!

I did buy via (Ebay) a couple of sets from the original manufacturer, that supplied Myford. These are excellent, as one would expect. I cannot see any reason at all to favour one system over the other. What I can say is that I have seen some poorly executed piston types. It all really comes down to the quality of the item, be it wedge or piston activated.

Andrew.

Hello Tony,

I can't find anything that is really relevant except for replacing the mandrel with a new Myford hardened version and phosphor bronze bearings. Maybe I am using the incorrect search terms?

Regards,

Andrew.

Hello Robbo,

That is the thing that bothers me! Scrapping at the top and bottom of the bearings is something that I feel could easily go wrong and once a mistake is made, then I will probably spiral out of control! The bearings appear to be thicker than the usual shell bearings on big ends and cranks of car and bike engines, so maybe I have more white metal to play with than I think!

I am probably worrying over nothing, but I usually like to practice and become relatively skilled before I tackle something new! I don't even know what sort of small scraper to use on such (to me) small plain bearings!

Tony,.

Regards,

Andrew.

Thanks for the tip, I shall search U tube to see if I can find the clips you mention

Does anyone know what the diameter of the ML7 mandrels is? I have reached the stage of installing the new white metal bearings and the mandrel.

I suppose that I am getting nervous and just hoping the bearing diameters are "within spec". The bearing areas are free from any major scoring. In fact they look remarkably polished and uniform. I have not yet "miked" them up for fear of finding them appreciably undersize!

I know I should just install things and see what play there may be. The only snag with this approach is that I have never scraped white metal bearings of such small size! I have done full size loco bearings before, but they are hardly in the same league for accuracy!

As I was fortunate enough to get a brand new set of white bearings, I just don't want to ruin them!

Andrew.

When I got my first lathe, maybe 40 years ago, I had both a 3 jaw and 4 jaw chuck. I nearly always used the 3 jaw, finding setting up a 4 jaw to be the work of the devil.

I can now quickly and easily centre a 4 jaw chuck BUT I would much rather use my 3 jaw if at all possible! I think those that recommend a 4 jaw as an "only" first chuck are doing a disservice to the total newcomer. Most beginners jobs can be done with a 3 jaw. At this point, the beginner has enough to worry about without having to set up a 4 jaw.

Andrew.

Steve,

A very impressive photograph! I have never seen such contrast on a rubbed surface. I didn't get my wires twisted and do appreciate that it is the US water based system we are talking of. I got my fingers twisted instead and didn't type what I intended!

I am one of those unfortunate people that get engineering blue just EVERYWHERE, except for what I am trying to coat! I assume the water based products are not nearly so messy?

I never expected this thread to reveal such a wealth of detail about scraping and systems used for highlighting high spots. It has been a real education and there may be more to come. I shall mull over all the helpful advice and see where to go. It is hardly expensive to try most suggestions (including the water based system). I can then see which one suits my needs best.

Thanks for such a response!

Andrew.

I am a little backwards in my artistic talents, can someone explain what "cement pigment" is. I am definitely not an artist!

Now that is a touch naughty, I should have the sense to Google "cement pigment". I am just being lazy!

Andrew.

That is a very interesting set of replies, seems the Stuart blue is a favourite . Not sure about going to the trouble and expense of importing it from the US though. I have a friend who has a house in the US and regularly commutes. Maybe I could get him to bring some back if I can find a retail outlet in the States!

I could have sworn that the stuff I used all those years ago was red lead, However I have some jewellers rouge and plenty of oil so I can make some up! Just a bit leary about the abrasive properties on my nice master plate!!!!

I have never heard of the two colour method before, it sounds intriguing. I can see the logic behind it and I am impressed by the simplicity. This seems to be requiring water based materials as you probably have to clean the plates down after scraping and repeating the process, or have I got this wrong?

Thanks for all your input, a simple thing like the colour for rubbing the plates together, turns up a wealth of unexpected information!

Thanks,

Andrew.