Post by thread:[EE] Obscure screw size

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'[EE] Obscure screw size'
2011\12\01@001839 by Oli Glaser

Hi all, I have a Hammond 1551R box into which fits a small PCB. The recommended shape of the PCB is given in the datasheet: (http://www.hammondmfg.com/pdf/1551R.pdf) I have received the PCB and it fits perfectly, but the Hammond box only came with the 2 screw for the lid and none for the PCB mount holes. The sizes specified are 2.5mm for the PCB hole diameter, but the screws are given as 32 x 3/16" self tapping. So the question is - what does this translate to in metric sizes? I get the 3/16" is probably the length, but what does 32 stand for? Is it for a 1/32" thread? I have trawled through pages and pages of all the many different "standards" - Whitworth, BAS, UTS, etc but I can't fit 32 into anything that seems to fit properly. The UTS (Hammond are US so I assumed this would be the most likely) is specified as X-Y where X is the diameter and Y is the thread turns per inch. 1/32 would give a diameter of 0.8mm and 3/16 means nothing in terms of turns per inch. Even if you swap them round it doesn't make sense. Whilst linking to the above datasheet I noticed it's actually different from the one I have, and gives #2 x 3/16" instead of the aforementioned 32 x 3/16". This makes more sense as #2 equates to 2.18mm diameter shank, but I'm still unsure as to the thread (not that it matters too much as it's self tapping, but I'd like to know anyway) I'm going to order some number 2 screws, but can anyone help me to confirm exactly what the numbers mean for future reference?

2011\12\01@004323 by William Wilson

In imperial units the 2.5mm screw would be a 3/32 inch diameter screw with 32 threads per inch and 3/16" long. Metric equivalent is M2.5x0.45 4.5mm long _____________________________________________________________________________ Cris Wilson Information Resource Consultant College of Architecture, Arts, and Humanities Clemson University 864-656-6081 ________________________________________ From: spam_OUTpiclist-bouncesTakeThisOuTmit.edu [.....piclist-bouncesKILLspam@spam@mit.edu] On Behalf Of Oli Glaser [oli.glaserKILLspamtalktalk.net] Sent: Thursday, December 01, 2011 12:18 AM To: Microcontroller discussion list - Public. Subject: [EE] Obscure screw size Hi all, I have a Hammond 1551R box into which fits a small PCB. The recommended shape of the PCB is given in the datasheet: (http://www.hammondmfg.com/pdf/1551R.pdf) I have received the PCB and it fits perfectly, but the Hammond box only came with the 2 screw for the lid and none for the PCB mount holes. The sizes specified are 2.5mm for the PCB hole diameter, but the screws are given as 32 x 3/16" self tapping. So the question is - what does this translate to in metric sizes? I get the 3/16" is probably the length, but what does 32 stand for? Is it for a 1/32" thread? I have trawled through pages and pages of all the many different "standards" - Whitworth, BAS, UTS, etc but I can't fit 32 into anything that seems to fit properly. The UTS (Hammond are US so I assumed this would be the most likely) is specified as X-Y where X is the diameter and Y is the thread turns per inch. 1/32 would give a diameter of 0.8mm and 3/16 means nothing in terms of turns per inch. Even if you swap them round it doesn't make sense. Whilst linking to the above datasheet I noticed it's actually different from the one I have, and gives #2 x 3/16" instead of the aforementioned 32 x 3/16". This makes more sense as #2 equates to 2.18mm diameter shank, but I'm still unsure as to the thread (not that it matters too much as it's self tapping, but I'd like to know anyway) I'm going to order some number 2 screws, but can anyone help me to confirm exactly what the numbers mean for future reference?

2011\12\01@012432 by Oli Glaser

On 01/12/2011 05:43, William Wilson wrote: > In imperial units the 2.5mm screw would be a 3/32 inch diameter screw > with 32 threads per inch and 3/16" long. > > Metric equivalent is M2.5x0.45 4.5mm long Thanks, that's very helpful. So the 32 is tpi and the 3/16" is length? Trouble is my PCB holes are the recommended 2.5mm, so I'll need a bit smaller I guess. I'll get the number 2 imperial which by my calculations is 2.18mm. Couple more questions: How can we be sure of the diameter when only given 32 x 3/16" for the screw size? What standard does this comply with? Is there any decent reference out there that explains this?

2011\12\01@013348 by Oli Glaser

I forgot to mention that on Mouser, I can only find one screw (out of 1204) with a 32 thread size and it's not the right length. On Digikey I get nothing either. there are 6 results for 3/16" but they are either 6/32" 8/32" or 4/40". Is this screw size really that hard to find or am I missing something?

2011\12\01@021811 by Spehro Pefhany

At 12:18 AM 12/1/2011, you wrote: >Hi all, > >I have a Hammond 1551R box into which fits a small PCB. >The recommended shape of the PCB is given in the datasheet: >(http://www.hammondmfg.com/pdf/1551R.pdf) >I have received the PCB and it fits perfectly, but the Hammond box only >came with the 2 screw for the lid and none for the PCB mount holes. The >sizes specified are 2.5mm for the PCB hole diameter, but the screws are >given as 32 x 3/16" self tapping. >So the question is - what does this translate to in metric sizes? I get >the 3/16" is probably the length, but what does 32 stand for? Is it for >a 1/32" thread? I don't see a "32" on that drawing, I see #2 x 3/16" 32 threads per inch (North American screws use the reciprocal of the pitch) is certainly plausible- typically this type of screw has a much coarser pitch than the equivalent diameter machine screw. In any case, this would be approximately a M1.8 Thread Forming fastener, also called K18, but you'd have to verify the size to be sure. Pitch at 0.8mm is about right. Here's one maker, along with some design rules for various plastics:- http://www.semblex.com/files/PT-Semblex.pdf Also note the Hammond part number 1551ATS100 for 100 pieces of screw, about 6 cents each.. if you don't feel like screwing around with substitutes. I would not be particularly gobsmacked if they were actually metric-- K18 4.5 or 5mm. >I have trawled through pages and pages of all the many different >"standards" - Whitworth, BAS, UTS, etc but I can't fit 32 into anything >that seems to fit properly. Thread forming screws designed for plastics have a completely different thread form from machine screws. Also different from those designed for metal. You might be able to use ones designed for metal, but they won't be ideal. >The UTS (Hammond are US so I assumed this would be the most likely) is Hammond is Canadian, headquartered in Guelph, Ontario., {Quote hidden}>specified as X-Y where X is the diameter and Y is the thread turns per >inch. 1/32 would give a diameter of 0.8mm and 3/16 means nothing in >terms of turns per inch. Even if you swap them round it doesn't make sense.. >Whilst linking to the above datasheet I noticed it's actually different >from the one I have, and gives #2 x 3/16" instead of the aforementioned >32 x 3/16". This makes more sense as #2 equates to 2.18mm diameter >shank, but I'm still unsure as to the thread (not that it matters too >much as it's self tapping, but I'd like to know anyway) >I'm going to order some number 2 screws, but can anyone help me to >confirm exactly what the numbers mean for future reference? Hope this helps.

2011\12\01@031024 by Oli Glaser

On 01/12/2011 07:18, Spehro Pefhany wrote: > I don't see a "32" on that drawing, I see #2 x 3/16" Yes, the datasheet for the same box I have on my laptop actually has 32 x 3/16" instead (I did mention this in my original post, think I got my datasheet from the product page on Farnell) Must be an older one that I have, maybe they changed it because someone like me couldn't figure it out :-) {Quote hidden}> 32 threads per inch (North American screws use the reciprocal of the > pitch) is certainly plausible- typically this type of screw has a much > coarser pitch than the equivalent diameter machine screw. In any case, > this would be approximately a M1.8 Thread Forming fastener, also > called K18, but you'd have to verify the size to be sure. Pitch at > 0.8mm is about right. Here's one maker, along with some design rules > for various plastics:- http://www.semblex.com/files/PT-Semblex.pdf > Also note the Hammond part number 1551ATS100 for 100 pieces of screw, > about 6 cents each.. if you don't feel like screwing around with > substitutes. I would not be particularly gobsmacked if they were > actually metric-- K18 4.5 or 5mm. Thanks, I will probably order some from Hammond too. I was manly wondering how to figure these sizes out or find a good reference to save time in future. I seem to spend an inordinate amount of time on the mechanical aspects of designs, so I figured it might be time to learn something about the relevant bits and hopefully make the process less painful. >> I have trawled through pages and pages of all the many different >> "standards" - Whitworth, BAS, UTS, etc but I can't fit 32 into anything >> that seems to fit properly. > Thread forming screws designed for plastics have a completely different > thread form from machine screws. Also different from those designed for > metal. You might be able to use ones designed for metal, but they won't be > ideal. Ah, I see. I'll see what I can find on threads for plastic. >> The UTS (Hammond are US so I assumed this would be the most likely) is > Hammond is Canadian, headquartered in Guelph, Ontario., Well, I was close.. :-) {Quote hidden}>> specified as X-Y where X is the diameter and Y is the thread turns per >> inch. 1/32 would give a diameter of 0.8mm and 3/16 means nothing in >> terms of turns per inch. Even if you swap them round it doesn't make sense. >> Whilst linking to the above datasheet I noticed it's actually different > >from the one I have, and gives #2 x 3/16" instead of the aforementioned >> 32 x 3/16". This makes more sense as #2 equates to 2.18mm diameter >> shank, but I'm still unsure as to the thread (not that it matters too >> much as it's self tapping, but I'd like to know anyway) >> I'm going to order some number 2 screws, but can anyone help me to >> confirm exactly what the numbers mean for future reference? > Hope this helps. Yep it does - thanks a lot.

2011\12\01@061701 by Walter Banks

Oli Glaser wrote: > Ah, I see. I'll see what I can find on threads for plastic. > > >> The UTS (Hammond are US so I assumed this would be the most likely) is > > Hammond is Canadian, headquartered in Guelph, Ontario., > > Well, I was close.. :-) . Whats 90 miles between friends Guelph is about 90 miles north of Buffalo, NY > >> specified as X-Y where X is the diameter and Y is the thread turns per > >> inch. 1/32 would give a diameter of 0.8mm and 3/16 means nothing in > >> terms of turns per inch. Even if you swap them round it doesn't make sense. > >> Whilst linking to the above datasheet I noticed it's actually different > > >from the one I have, and gives #2 x 3/16" instead of the aforementioned > >> 32 x 3/16". This makes more sense as #2 equates to 2.18mm diameter > >> shank, but I'm still unsure as to the thread (not that it matters too > >> much as it's self tapping, but I'd like to know anyway) 32 x 3/16 is a typo it should have been #2 x 3/16. # is a shifted 3 w...

2011\12\01@070101 by alan.b.pearce

> 32 x 3/16 is a typo it should have been #2 x 3/16. # is a shifted 3 That would make sense ... on a US keyboard. On a UK keyboard shift 3 is £, # is an unshifted char just above the RH shift key. But a good catch Walter. Oli's email address shows as @talktalk.net, which is a UK ISP, I don't know if they have a presence in other countries ... -- Scanned by iCritical.

2011\12\01@070331 by KPL

> > 32 x 3/16 is a typo it should have been #2 x 3/16. # is a shifted 3 > It's incredible, you Americans can easily understand those mystical imperial sizes even when mistyped, but quite often have trouble with metric :) -- KPL

2011\12\01@075105 by Dave Tweed

Oli Glaser wrote: > On 01/12/2011 07:18, Spehro Pefhany wrote: > > I don't see a "32" on that drawing, I see #2 x 3/16" > > Yes, the datasheet for the same box I have on my laptop actually has 32 > x 3/16" instead (I did mention this in my original post, think I got my > datasheet from the product page on Farnell) > Must be an older one that I have, maybe they changed it because someone > like me couldn't figure it out :-) I think it's pretty likely that the "32" on the first datasheet is simply a typo that was corrected to "#2" on the newer version -- on many keyboards, the "#" is the shifted version of the "3" key. 32 TPI is way too fine for a self-tapping screw intended for plastic. -- Dave Twee

2011\12\01@080311 by Bob Ammerman

IIRC the standard thread pitches for numbered screw sizes are: 2-56 4-40 6-32 8-32 10-32 10-24 Any other pitch is going to be hard to find. -- Bob Ammerman RAm Systems

2011\12\01@080700 by Bob Ammerman

> Whats 90 miles between friends > Guelph is about 90 miles north of Buffalo, NY Who is in Buffalo? Besides me of course. -- Bob Ammerman RAm Systems

2011\12\01@081429 by alan.b.pearce

> IIRC the standard thread pitches for numbered screw sizes are: > > 2-56 > 4-40 > 6-32 > 8-32 > 10-32 > 10-24 > > Any other pitch is going to be hard to find. I am in the process of sourcing some 0-80 screws ... -- Scanned by iCritical.

2011\12\01@084229 by Harold Hallikainen

Speaking of screw sizes... Since we sell our products internationally, I've been suggesting moving away from US hardware and towards metric. So far no one agrees. We really do get stuck on measurement systems. When I was a kid, my father gave me a job at his company. My first job was sorting screws that had gotten mixed together. He said "I have engineers that don't know screw sizes." He wanted to make sure I wasn't one of them. But, I still don't know metric screw sizes. Speaking of measurements, how many are designing circuit boards using mm, and how many using mils (thousanths of inch)? Harold -- FCC Rules Updated Daily at http://www.hallikainen.com - Advertising opportunities available! Not sent from an iPhone

2011\12\01@085222 by peter green

Harold Hallikainen wrote: > Speaking of screw sizes... Since we sell our products internationally, > I've been suggesting moving away from US hardware and towards metric. So > far no one agrees. We really do get stuck on measurement systems. When I > was a kid, my father gave me a job at his company. My first job was > sorting screws that had gotten mixed together. He said "I have engineers > that don't know screw sizes." He wanted to make sure I wasn't one of them.. > But, I still don't know metric screw sizes. > It's certainly much easier to get metric screws than US screws* here in the UK > Speaking of measurements, how many are designing circuit boards using mm, > and how many using mils (thousanths of inch)? > Personally I design in whichever matches the bulk of components on the board and/or the system into which the board will be integrated. > Harold > * with the exception of the screws commonly used in PCs (why the hell do PCs use a metric screw and a UNC screw of such similar size anyway....

2011\12\01@085431 by alan.b.pearce

> Speaking of measurements, how many are designing circuit boards using mm, and how > many using mils (thousanths of inch)? We use mm for most things, but occasionally use imperial to set out a connector footprint, or similar devices where it is easier to work in imperial. It can make tracking a PCB a bit awkward at times, getting the track to make the connection, though. -- Scanned by iCritical.

2011\12\01@085856 by PICdude

Quoting KPL <.....kpl.listesKILLspam.....gmail.com>: > It's incredible, you Americans can easily understand those mystical > imperial sizes even when mistyped, but quite often have trouble with > metric :) It's not understanding metric that's the problem (actually it's much easier), but it's thinking in metric. If you show me a table for example, I can guess it's length in feet, then convert. But I can't naturally guess in metres. Cheers, -Neil.

2011\12\01@102727 by Carey Fisher

On Thu, Dec 1, 2011 at 12:18 AM, Oli Glaser <EraseMEoli.glaserspam_OUTTakeThisOuTtalktalk.net> wrote: > Hi all, > > I have a Hammond 1551R box into which fits a small PCB. > The recommended shape of the PCB is given in the datasheet: > (http://www.hammondmfg.com/pdf/1551R.pdf) > I have received the PCB and it fits perfectly, but the Hammond box only > came with the 2 screw for the lid and none for the PCB mount holes. The > sizes specified are 2.5mm for the PCB hole diameter, but the screws are > given as 32 x 3/16" self tapping. > So the question is - > ........................................................ > I'm going to order some number 2 screws, but can anyone help me to > confirm exactly what the numbers mean for future reference? > Oli, Here are two actual people you can talk to at Hammond about technical questions. They were all very helpful to me and I'm sure at least one can help you. *Jeremy N. Sorensen* Business Development Test & Measurement Specialist T (330)523-4100 - *direct* T (800)463-9275 x34100 F (888)551-4801 E jsorensenspam_OUTnewark.com <@spam@ynameKILLspamnewark.com> *Tom Ballou* Electronic Technical Sales/ Quotations Hammond Manufacturing Co., Inc. p- 716-630-7030 x230 / f- 716-630-7042 / e-mail KILLspamtballouKILLspamhammfg.com > > Care

2011\12\01@105604 by John Gardner

....those mystical Imperial sizes... A friend who works for a <large> aerospace/defense firm says in-house they uses "standard" units. They do have one customer - NASA - which requires Metric documentation, so docs headed that way are run through a units conversion pgm first. I asked him if that had anything to do with "missing" Mars some years ago - He says not... Jac

2011\12\01@112418 by Dwayne Reid

At 06:42 AM 12/1/2011, Harold Hallikainen wrote: >Speaking of screw sizes... Since we sell our products internationally, >I've been suggesting moving away from US hardware and towards metric. So >far no one agrees. We really do get stuck on measurement systems. When I >was a kid, my father gave me a job at his company. My first job was >sorting screws that had gotten mixed together. He said "I have engineers >that don't know screw sizes." He wanted to make sure I wasn't one of them. >But, I still don't know metric screw sizes. I'm in the same boat - I can sort North American screws by eye but get lost when looking at Metric hardware. >Speaking of measurements, how many are designing circuit boards using mm, >and how many using mils (thousanths of inch)? Imperial units for all of the initial layout / placements. I use Metric dimensions only when creating footprints that are in Metric. My CAD package (Cadint) switches seamlessly between Imperial and Metric just by tapping the "U" key (Units) on the keyboard but I do most all of my initial placements and routing in Cadint's older sibling: EE Designer II. Then I import into Cadint for any finicky stuff and for Gerber file generation. My preferred grid spacing is 0.025" or octave increments above, at least when I'm first plopping footprints onto the board. It bugs the hell out of me when one of my co-workers places stuff a few mils off the 25 mil grid for no good reason - it makes the board look 'sloppy' to my eye as well as being harder to route 'neatly'. dwayne -- Dwayne Reid <RemoveMEdwaynerTakeThisOuTplanet.eon.net> Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax http://www.trinity-electronics.com Custom Electronics Design and Manufacturing

2011\12\01@120629 by Walter Banks

KPL wrote: > > > > 32 x 3/16 is a typo it should have been #2 x 3/16. # is a shifted 3 > > > > It's incredible, you Americans can easily understand those mystical > imperial sizes even when mistyped, but quite often have trouble with > metric :) I am a Canadian who regularly works in both imperial and metric. Hammond is a Company in Quelph (about 25 miles) from where I live that has been manufacturing packaging for electronics since the first world war. For many years practically everything they produced was painted in battleship grey Many of their products have been in production for at least half a century. http://www.hammfg.com/corp/about.htm Walter..

2011\12\01@120709 by Carl Denk

And then there is the issue of very similar sizes, that by eye you can't tell one size from the other. I find it's necessary to take a know America or Metric nut or bolt and determine which it is. To complicate, some of the equipment around including Ford autos and a New Holland compact tractor have both varieties scattered about. Now should I bring a 10 or 11 mm. or 3/8" open end (spanner) wrench. :

2011\12\01@143823 by KPL

> >> It's incredible, you Americans can easily understand those mystical >> imperial sizes even when mistyped, but quite often have trouble with >> metric :) > > It's not understanding metric that's the problem (actually it's much > easier), but it's thinking in metric. If you show me a table for > example, I can guess it's length in feet, then convert. But I can't > naturally guess in metres. > > Cheers, > -Neil. I did not mean imperial dimensions as such, but threaded parts, their multiple standards, varieties, and markings. I can more-or less easily convert or imagine stuff in imperial units now, since I am reading a lot of technical texts written by Americans. But for threads it's completely different story. There is standard row of diameter/pitch, for all the other cases pitch is written in a blueprint. -- KPL

2011\12\01@173011 by jim

Oli, I looked up this box and I see #2 self tapping screws for the PCB, not 32. Apparently when you went to type the tic-tac-toe board for number, you didn't shift the keyboard to get the upper character. With that bit of info out of the way, the #2 refers to the nominal diameter of the screw. And of course, the 3/16's is the langth of the threaded portion from bwloe the head to the tip. The nominal diameter of a #2 self tapping screw is .086 inches, which would equate to just under 2.2mm (.086 x 25.4) Regards, Jim > ---{Original Message removed}

2011\12\01@180938 by Sergey Dryga

<alan.b.pearce <at> stfc.ac.uk> writes: > > > IIRC the standard thread pitches for numbered screw sizes are: > > > > 2-56 > > 4-40 > > 6-32 > > 8-32 > > 10-32 > > 10-24 > > > > Any other pitch is going to be hard to find. > > I am in the process of sourcing some 0-80 screws ... > McMaster have #2-32 self-tapping screws: www.mcmaster.com/#tapping-screws/=f6fp8m they also have 0-80, 27 products just for pan-head. Good luck, Sergey Dryga http://beaglerobotics.com

2011\12\01@182355 by Bob Ammerman

{Quote hidden}>> > IIRC the standard thread pitches for numbered screw sizes are: >> > >> > 2-56 >> > 4-40 >> > 6-32 >> > 8-32 >> > 10-32 >> > 10-24 >> > >> > Any other pitch is going to be hard to find. >> >> I am in the process of sourcing some 0-80 screws ... >> > McMaster have #2-32 self-tapping screws: > www.mcmaster.com/#tapping-screws/=f6fp8m > they also have 0-80, 27 products just for pan-head. > > Good luck, > > Sergey Dryga Yeah, I missed the "self-tapping" part and totally forgot about #0 screws. -- Bob Ammerman RAm Systems

2011\12\01@205218 by Oli Glaser

On 01/12/2011 11:59, spamBeGonealan.b.pearcespamBeGonestfc.ac.uk wrote: >> 32 x 3/16 is a typo it should have been #2 x 3/16. # is a shifted 3 > That would make sense ... on a US keyboard. On a UK keyboard shift 3 is £, # is an unshifted char just above the RH shift key. But a good catch Walter. > > Oli's email address shows as @talktalk.net, which is a UK ISP, I don't know if they have a presence in other countries ... Ahh, that really makes sense yes! Thanks Walter - it will stop bugging me now :-) Alan is also right, I am in Manchester UK so my # is over the RH shift.

2011\12\01@210330 by Oli Glaser

On 01/12/2011 15:26, Carey Fisher wrote: > Oli, Here are two actual people you can talk to at Hammond about technical > questions. They were all > very helpful to me and I'm sure at least one can help you. Thanks, will keep a note of those.

2011\12\01@210942 by Oli Glaser

On 01/12/2011 22:30, TakeThisOuTjimEraseMEspam_OUTjpes.com wrote: > Oli, > > I looked up this box and I see #2 self tapping screws for the PCB, not > 32. Apparently when you went to > type the tic-tac-toe board for number, you didn't shift the keyboard to > get the upper character. It wasn't me, it was someone at Hammond :-) As I mentioned in my first mail the version of the datasheet I had originally had 32 x 3/16". I just looked on Farnell to see if it's still like that and it is: http://www.farnell.com/datasheets/10332.pdf

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