BA or Metric

[Basil]

I'm starting a Seal Major 30cc build. My first full engine machining project. Getting ready to order a set of small taps and dies. Is it necessary these day to build with BA or is there a greater selection going metric? I should mention I'm partial to Allen heads. I would not want to swap back and forth if not absolutely necessary. On past projects I have seen advantage in swapping between imperial and metric on occasions where available space has been an issue. Does this ring true also for BA? Thank you. ps. Who has really good quality kits?

 

[IanN]

Hi Basil,
Simple answer - it makes no difference at all. If you already have a good selection of BA taps and dies, use those. If you are already the proud owner of appropriately sized metric tooling, use those.

Other advice - use what is easily obtainable locally (certain forms are more or less common in different countries)

It all boils down to your personal convenience

All the best,
Ian

 

[abby]

Many of us aged model engineers have large stocks of BA fasteners , mostly I suppose of the hex head variety . It makes sense from a cost point of view to use what we have .
my own stock , collected over the years mainly from long gone ME's , range from 2 BA to 12 BA with 2 head sizes for the smaller threaded screws.
I also have taps and dies to match , with some left hand threads too.
I have 14 and 16 BA taps inherited from my father which neither he nor I have ever used ( he worked at a factory making endmills and taps)
I guess that sooner or later these will be in some other ME's workshop cupboard as I could never use all the fasteners nor wear out the tools.
However if I was just starting out I would go metric , you will find socket head screws more readily available in metric sizes too.
My own experience with small socket heads , particularly the countersunk variety , is the ease with which the socket fails .
Maybe I am getting ham-fisted but I find it very easy to "round off" the socket in M2 countersunk head screws.
If you are in the UK you can find good second hand BA taps and dies very cheap by the way.
Dan.

 

[Basil]

Thank you for your replies. There seems to be a lot more selection of metric Allen heads than in BA plus I already have a few small Metric taps. So metric it is. Much Appreciated.

 

[SmithDoor]

I would look see what is on self at local stores.
It will pay when a screw or nut when need one in a rush.

Where I live it is inch but that USA.

Dave

I'm starting a Seal Major 30cc build. My first full engine machining project. Getting ready to order a set of small taps and dies. Is it necessary these day to build with BA or is there a greater selection going metric? I should mention I'm partial to Allen heads. I would not want to swap back and forth if not absolutely necessary. On past projects I have seen advantage in swapping between imperial and metric on occasions where available space has been an issue. Does this ring true also for BA? Thank you. ps. Who has really good quality kits?

 

[goldstar31]

Who has really good quality kits?

Hemingwaykits who will supply the appropriate fasteners.
I suppose that the once you have a decent kit, the previous correspondence will have been unnecessary.

I DID see the price in the UK
and then the carriage etc

But you DID ask

 

[tornitore45]

Maybe I am getting ham-fisted but I find it very easy to "round off" the socket in M2 countersunk head screws.

I found this to be prevalent with SS hardware. The Alloy (black) screw have a much better resistance to rounding.
Also for all small Allen Keys make sure they are sharp, grind away the buggered end until is a crisp HEX.

 

[Richard Carlstedt]

...............................................................
My own experience with small socket heads , particularly the countersunk variety , is the ease with which the socket fails .
Maybe I am getting ham-fisted but I find it very easy to "round off" the socket in M2 countersunk head screws.....................
Dan.

That failure is not due to the screw socket !
It is due to the quality that you purchase and is very common with Metric Screws in particular.
Metric material standards are all over the Map ( sorry about that, but true !)
You can get screws in Din 5.8, Din 8.8, Din 10.9 and Din 12.9 and your failures are due to not using 12.9 class screws.
Din 12.9 screws use steel with a Tensile Strength of 170,000 Pounds or more.
Most Chinese sourced screws are the lowest grade steel ( ie 5.8 ) and failure is imminent !
In the USA, it is illegal to make low strength socket head screws according the ANSI 1962 standards and thus all socket head screws - Whether Metric or Standard inch size- must be made with 170,000+ PSI strength steel minimum . Trade names that are reliable for this ( 180 K PSI ) are Unbrako , Allen, Holo-Krome and Camcar. As I said, it is illegal to make anything less than 170 K in the US , but not illegal to sell lesser products, thus we have Chinese junk.

Rich

Edit:
Mauro has good advice, Stainless Steel has lower strength than 12.9 by nature , so his advice is excellent

 

[Iampappabear]

I have taps and dies in metric, BA & Unified, and decide when reviewing the model what thread type to use. One thing I consider when deciding thread form is the diameter of any rods that will require threads. 7 BA works with 3/32" dia and 2 BA which works with 3/16" diameter rod. 5-40 works well with 1/8" dia rod and 10-32 works with 3/16" dia. Residing in Canada metric small diameter metric rod if not to easy to procure so seldom use metric threads.

 

[tornitore45]

I am surprised to hear that metric stock is not the most common in Canada. Not to difficult to get in USA.

 

[packrat]

McMaster-Carr sells metric drill rod, to bad they do not ship to Canada..If you want to change BA threads to U.S sizes
here is a size caparison chart, if you wanted to use U.S Taps and dies. I for one would us BA threads the bolts and nuts witch look
much better on a model {unless you make them your self}

 

[petertha]

I am surprised to hear that metric stock is not the most common in Canada. Not to difficult to get in USA.

Its the sad reality, at least in my region of Canada & specifically model engineering sizes & quantities. Not impossible to find but not exactly prevalent. You can find typical 100 qty boxes at machinery supply places like KBC or Travers. They tend to start around the M4/M5 range though. There seems to be more specialty fastener places in eastern Canada, closer to that industry I suppose. I highly doubt much if anything is made here. So we can talk about official standards or bilingual units but IMO if it wasn't for Ebay & Ali, life would be miserable for a hobbyist. McMaster is awesome 1-stop supplier for our USA friends, but alas they only ship to CDN companies/institutions, not individual mortals.

I agree though, my experience with offshore metric hardware (almost always from Asia) ranges from excellent to something less. Sometimes they appear to stick to iso/din standards & other times its just a advertising label, real or imagined.

 

[ajoeiam]

Its the sad reality, at least in my region of Canada & specifically model engineering sizes & quantities. Not impossible to find but not exactly prevalent. You can find typical 100 qty boxes at machinery supply places like KBC or Travers. They tend to start around the M4/M5 range though. There seems to be more specialty fastener places in eastern Canada, closer to that industry I suppose. I highly doubt much if anything is made here. So we can talk about official standards or bilingual units but IMO if it wasn't for Ebay & Ali, life would be miserable for a hobbyist. McMaster is awesome 1-stop supplier for our USA friends, but alas they only ship to CDN companies/institutions, not individual mortals.

I agree though, my experience with offshore metric hardware (almost always from Asia) ranges from excellent to something less. Sometimes they appear to stick to iso/din standards & other times its just a advertising label, real or imagined.

IMO - - - - Ali has become a royal pita lately.
Shipping seems to be the problem and Ali--shipping is terrible.
Ali then blames the vendors and really its ali itself that has been a real cow!
I have become quite hesitant re: ordering anything of a value greater than say $100 CAN.

 

[terryd]

That failure is not due to the screw socket !
It is due to the quality that you purchase and is very common with Metric Screws in particular.
Metric material standards are all over the Map ( sorry about that, but true !)
You can get screws in Din 5.8, Din 8.8, Din 10.9 and Din 12.9 and your failures are due to not using 12.9 class screws.
Din 12.9 screws use steel with a Tensile Strength of 170,000 Pounds or more.
Most Chinese sourced screws are the lowest grade steel ( ie 5.8 ) and failure is imminent !
In the USA, it is illegal to make low strength socket head screws according the ANSI 1962 standards and thus all socket head screws - Whether Metric or Standard inch size- must be made with 170,000+ PSI strength steel minimum . Trade names that are reliable for this ( 180 K PSI ) are Unbrako , Allen, Holo-Krome and Camcar. As I said, it is illegal to make anything less than 170 K in the US , but not illegal to sell lesser products, thus we have Chinese junk.

Rich

Edit:
Mauro has good advice, Stainless Steel has lower strength than 12.9 by nature , so his advice is excellent

Hi Rich,

Not sure why you are quoting DIN standards here, they are not metric per se they are German as are all DIN (Deutsches Institut für Normung ) standards. Standards are now being integrated across Europe as 'EN' standards and DIN is now considered out of date. ISO metric standards are aligned to the EN standards so there is only one ISO set of standards therefore I can't see how you can make a claim that metric standards are 'all over the map' by referring to what amounts to an archaic system.. EN steels have been sold in the UK for many years.

Chinese screws come in all steel grades based on GB standards (now integrated into EN) which relate to AISI standards. You get what you order from any source - order junk and you get just that and I suspect that is what suppliers and importers do so it it the fault of the importers and suppliers of your country that you get 'junk' not the Chinese. If you wish to buy better then order to spec.

TerryD

 

[terryd]

Its the sad reality, at least in my region of Canada & specifically model engineering sizes & quantities. Not impossible to find but not exactly prevalent. You can find typical 100 qty boxes at machinery supply places like KBC or Travers. They tend to start around the M4/M5 range though. There seems to be more specialty fastener places in eastern Canada, closer to that industry I suppose. I highly doubt much if anything is made here. So we can talk about official standards or bilingual units but IMO if it wasn't for Ebay & Ali, life would be miserable for a hobbyist. McMaster is awesome 1-stop supplier for our USA friends, but alas they only ship to CDN companies/institutions, not individual mortals.

I agree though, my experience with offshore metric hardware (almost always from Asia) ranges from excellent to something less. Sometimes they appear to stick to iso/din standards & other times its just a advertising label, real or imagined.

Hi Peter,

I suggest that you find a friend in the UK as metric, Whitworth, BA and AINSI fasteners made in the UK are available in small quantities and would be relatively cheap to post. Alternatively try eBay.uk and you may find suppliers who sell small quantities under the eBay global shipping program which I find excellent.

TerryD

 

[peter2uat]

IMO - - - - Ali has become a royal pita lately.
Shipping seems to be the problem and Ali--shipping is terrible.
Ali then blames the vendors and really its ali itself that has been a real cow!
I have become quite hesitant re: ordering anything of a value greater than say $100 CAN.

Well, in my experience most goods from ali come in quite punctually after about a month. A mini-PC ($230) I ordered Sept. 9 was delivered Oct.21. So, some things might get stuck somewhere in post offices, customs ot transport services. I have the sad tale that one poor seller tried to send me a small pwm-controller with big LEDs (price $15 so nothing really expensive) three times, got rejected every time at his PO (who knows why), then tried another service, and I'm still waiting to see the status change from -in transit- to something better - after two months. I have ordered and got an identical controller from another seller in the meantime. Maybe the problems are in some regional regulations - who knows - bureaucrazy?

 

[terryd]

Well, in my experience most goods from ali come in quite punctually after about a month. A mini-PC ($230) I ordered Sept. 9 was delivered Oct.21. So, some things might get stuck somewhere in post offices, customs ot transport services. I have the sad tale that one poor seller tried to send me a small pwm-controller with big LEDs (price $15 so nothing really expensive) three times, got rejected every time at his PO (who knows why), then tried another service, and I'm still waiting to see the status change from -in transit- to something better - after two months. I have ordered and got an identical controller from another seller in the meantime. Maybe the problems are in some regional regulations - who knows - bureaucrazy?

Hi Peter,
I have had th same experience with Chinese suppliers be it AliExpress, Banggood or eBay, I have generally had excellent delivery times recently. Especially eBay as I think that they have complained to suppliers about late deliveries. here in the UK I have had delivery times measured in days rather than weeks quite often. Yoj are probably correct about delays being due to Customs and delivery services, especially in the US if what I hear about the goings on at USPS are only half true.

TerryD

 

[Apprentice707]

There are many knockers of Chinese goods and delivery so here is what happened when I ordered a 5" 6 jaw self-centering lathe chuck direct from China.

I was on holiday in Florida, it was a Monday morning and I was due to fly back to the UK the next day arriving early on the Wednesday morning. I was just browsing eBay when I saw the chuck at a good price so I bought one and asked for it to be delivered to my UK home. No problems there they gave me a delivery date in two weeks' time and I concluded the process.

The trip back to the UK went as planned and I arrived at my home in Ipswich around midday on the Wednesday. At 2 pm a knock on the door by a Hermes courier with a heavy wooden box announced the arrival of my chuck, about 51 hours after I ordered it in the USA. Unbelievable, it takes the Royal Mail longer to get a letter from London to the same address.

In fairness, I have waited 3 months for small items to come from China so perhaps the chuck delivery was a one-off.

Happy machining everyone

B

 

[wazrus]

I've taken to using metric fasteners of all shapes and sizes. I have hundreds of socket head capscrews in many lengths, in 1.6mm 2.0mm and 2.5mm, all in stainless steel which, I believe, has a fairly high tensile rating. There are also many, many countersunk in hex socket style, Philips and slotted and there are lots with a sort of rounded Philips head, from 1.0mm through 1.4mm, 1.6, 2.0 etc. I've also sort of replaced British Standard Brass with 1.0mm pitch tackle, in sizes from 6.0mm up to 38mm. There is usually a choice offered between stainless and 'zinc' (zinc plated, magnetic) which I often prefer when using screws below 2.0mm. There are also nuts in all sizes and i have nylok nuts down to 1.4mm. All of this and taps and dies have been Chinese and I have to report that the quality evident in the larger 1.0mm taps is excellent. I have also sourced taps and dies in 1.2, 1.4 etc and one surprise was 2.2mm. In short, anything seems to be available. Some of the Chinese brands of very small drill are a rubbish, but other brands are quite good. Then again, it all usually comes down to point grinding in these small sizes and I do routinely inspect the tips to ensure that they're OK. A small, fine grit wheel is essential and a pair of eyeglass magnifiers!