Tapping pure aluminium

Only that someone has to think about the fire risk!

Oh, and back in the day, making sure that the workforce didn't drink Meths was a problem. We forget how much education has improved: one of my Great Uncles believed that any 'Alcohol' or 'Spirit' was drinkable. He'd been in the Army and drunk Metal Polish...

Dave

It;s not the drinking of it that is a problem. It's the blindness and the brain damage that can follow. Ironically, the cure is to drink proper ethanol. It converts the formaldehyde that forms in the metho drinker's stomach into a less harmful chemical, or something. So the emergency room doctor told me on night shift at the hospital where I worked. In the absence of the hospital pharmacist to dispense pure ethanol at 4am, the good doctor had to give the miscreant a big slug of his own best scotch from his office. So we all sat around and had one, just to make sure old mate was OK.

The forman at the place I worked at in the 70s used his spit on tapping small holes countersinking on soft aluminium, Ideal for a quick fix if nothings available

Bob

Robert and Clive, we used to use tri-lobe thread forming screws in 6mm thick mild steel. I think we got ours from Lancaster Fastenings. They were used for securing cable trays and saved time and broken taps as they were often being used in hard to access positions. It became an economically viable process when battery powered drills and nut drivers became cheap and reliable.

Martin C

Ha! Ha! never a problem for me Dave -- I'm T-total !

John

Outside any modern, probably very expensive, specific fluid my view on using paraffin as lube on ali is based on many years at work and at home turning and milling all grades of the stuff.. WD 40 does work but nowhere as well as paraffin (kerosene) If WD40 is used to improve surface finish on lathe or mill then the fumes created can soon lead to quite unpleasant respiratory issues and I've definitely been there!.

Meths is alcohol - not a lube at all but okay for cleaning the part after of course but then acetone is so much better.

Best - Tug

Edited By Ramon Wilson on 01/02/2023 12:09:12

Thanks Tug. I'm awaiting a set of M2.5 taps to replace the the one I broke and shall have a go with paraffin. Your suggestion took me down memory lane - I don't think I've bought paraffin since I was ten, when I converted my dad's garden weed sprayer into a flamethrower. It worked well, but he wasn't pleased when he found out. Back then you just took a empty pop bottle to the ironmonger and bought by the pint. It was an enticing pink colour - I remember passing a group of 'street bullies' with a bottle - 'giz a swig'. I relinquished my bottle, stopped long enough to see the chieftan take a pull, then ran for my life.

To return to the point - it seems that it's still available so I shall buy some.

On cleaning, petroleum ether (a light petroleum fraction) is even better than acetone for degreasing - the 40-60 degree stuff has a similar volatility to acetone but being composed of non-polar hydrocarbons is generally a more powerful solvent for workshop oily/greasy stuff in my experience.

Robin.

Castor oil is very good for small taps in the soft aluminium alloys including the very soft and gummy near pure aluminium. Another oil that is very good is the Blaser 35 cutting oil. I have used both, and the blaser is an easier clean up over the castor oil. Castor oil may be easier to get a hold of. If the castor is too thick, it can be thinned with vodka or kerosene , but I try to avoid kero as much as I can. Castor oil will help to keep the tapped hole to be nice and close to size. I start with the taper tap first in the soft stuff and break the chips quite often and then back the tap out and clean etc.

Ha! Robin, it's a far day from taking your can to the local hardware shop or the weekly van delivery of 'Aladdin'. I find a garden centre the best source for it these days.

As a matter of interest what kind of tap wrench are you using - If its the flat bar type and you are doing it free hand it's very easy to wring. Couple that with the material and it can be a disaster waiting to happen. Not knowing your circumstances but if you can support the tap in a drill chuck to keep it aligned it makes a big difference. I also have a small knurled disc about 18 mm dia. with a grub screw though the side for drive to use on small taps - the control is far better.

A very good, but relatively expensive, tapping fluid for ali is that sold by TapMatic - this also brilliant on brass, making a dullish drill bit cut like new whilst the fluid is in contact. A litre was well over twice the price for a litre as opposed to 4 litres of paraffin.

Disagreeing with you Neil, is not something I would have imagined doing but your use of castor oil is somewhat surprising mainly from the clean up point of view. I've never tried it on ali for tapping so don't doubt your comment that it will work but it's the most sticky gummy substance to deal with - just look how a model diesel will gum up not to mention it's ability to transfer to everything you touch to leave the same residue.

No, I've used both for long enough to know which one to use - your comment " you try to avoid Kerosene as much as you can" is also surprising - can you say why?

I use it (kerosene) all the time in the workshop for cleaning and lubricating - it's easy to clean off too. A mixture of 90% and 10% oil makes for a good lapping lube, a wipe over the lathe or mill after cleaning down etc etc. It doesn't dry hard like castor eventually does - that usual requires a solvent or heat to resolve.

Each to his own of course but my money's on the Paraffin

Best - Tug

A cutting oil called glowcut was sold in NZ, it was amazing stuff. It was castor oil thinned with 111 trichlorethane. Nasty stuff. I have also used the TapMatic fluid for Aluminium too. It's also good stuff. Castor oil is a truly amazing oil, but really messy as Tug mentions. To align the tap, if you have the room, make a guide that if a slide fit to the body of the tap. Hold it over the hole and the tap will self align to the drilled hole. It works really well on making parts for model planes like tapping the holes in the engine pans, that often take M2.5 securing screws.

The Tapmatic for Aluminium is no longer available here in NZ.

My main reason for avoiding kerosene, is the vapour off it effects my breathing. Paraffin oil, like baby oil is Ok , and so is the denatured industrial lubricant like D80, does not effect me. But JetA1 and the kero sold at the local hardware store is no good for me.

Neil

My old boss always said that when using very small drills and taps,spit was the finest lubricant ,that was back many years ago ,in the days before Rocol ,though when I make propane gas jets for the burners in hot tube gas engines using drills around no 75/77 i still use spit on the drill.I have not tried paraffinor kerosene on aluminium,though I suspect that kerosene (Heating oil) would be better as it is not so refined,the old paraffin that was sold by ironmongers was possiblly somewhere in between,the later refined paraffin ,pink or blue depending on the manufacturer and still sold today at very high prices. Find a friend who has oil heating and scrounge some kerosene off him. Aliminium extrusions can be very sticky so avoid deep threaded holes,I would avoid going past twice diameter on a small tapped hole,and also try drilling a larger size tapping drill and use a drop of Rocol cutting fluid.

In the context of heating oil - make sure it IS kerosene, 27 sec, NOT gasoil/diesel at 32sec ! Noel.

Thanks Neil, That's a good enough reason as any .

I guess we are all different as it has no effect on me in that way at all. WD40 as said is another matter - the last company I worked for bought it by the 25 litres and we all had hand pump spray bottles to fill and use it with. As well as working the Haas there I also did a fair bit of turning and used it a lot to begin with - it did not take long for my lungs to really respond to it. I find it a pleasant smell but rarely use it in the workshop and never on any machining because of that reaction

Nigel - I expect days of old had many an old trick - keeping a bottle of spit for continuous use on a batch job just doesn't appeal though I'm afraid

In the days before Rocol there were of course the tallow sticks bought in varying diameter sizes to suit the tapping hole and later of course that horrible smelly stuff called Trefolux - good product but a bit too greasy for my liking. Strangely enough I react to Rocol too - if I had a job where it was in continuous use the skin around my nose would begin to crack and split - quite sore.

Following Robin's comment I looked for petroleum ether earlier. It's much dearer than acetone. A litre is £20-25 as opposed to around £25 for 5 litres of acetone.

I also use cellulose gun cleaner as a basic cleaner for many tasks including cleaning airbrushes but I need to wear a mask for anything but the smallest of exposures.

Best - Tug

I did actually start the thread with the tap held in a drill press chuck which is what I normally do - then go over to to a flat bar type wrench when the tap seems established to get a better 'feel'. Normally I buy plug taps because they seem OK for both blind and through holes provided they are guided at the start. In this case I had only a taper tap in my box, and that might have been part of the problem - inexperience in using the things. Because my smallest tap wrench didn't grip well I used small drill chuck held in my hand - which was a mistake, too heavy to give good control and feel. I'll make a knurled wheel as you suggest. Though Taptites may the practical answer in this case I'll plod on with tapping out of interest. With paraffin! I'll also make a guide, easy enough to do.

I was surprised to see how expensive pet ether is these days - I have a supply left over from my working days when it was sloshed about pretty liberally

Regards, Robin.

Edited By Robin Graham on 02/02/2023 22:49:07