Fastener Conundrum

[steviec_lj]

On with putting a Drummond Roundbed back together at the moment, after bathing almost everything in Citric Acid for a couple of days to remove the worst of the crud.

The minor problem I have now encountered is with a couple of saddle bolts.

They're not M12x1.5, and they don't seem to be M14x1.5 either.

Its a coarse thread. M12 cleared the "nut" but it looks like its going to seriously mess the bolts up if I run over them with an M12 die. M14x1.5 and M14x2 both seem far too slack too.

Any ideas? Picture to follow...

 

[Spark plug]

Are you sure it's metric? Could it not be 1/2".

Get an accurate measurement of the thread OD then go from there

 

[Rig Pig]

Probably whitworth given the age of the machine, measure and google!

 

[steviec_lj]

To be honest, I'd not thought of measuring it. Stupid, I know.

I shall measure and source in the morning. Done enough for today I think

 

[steviec_lj]

Here's the picture. I'll have a measure tomorrow however.

Thanks

 

[Rig Pig]

The middle one looks pre ww2 whitworth with a head that size.

 

[BrokenBiker]

another vote for whitworth. my r and a is all whitworth except the bolts holding the chuck to the backing plate which are m6x1

 

[steviec_lj]

Thanks, that should narrow the search down a little...

 

[graffian]

Are you sure it's metric? Could it not be 1/2".

Get an accurate measurement of the thread OD then go from there

If .472"x14.xxtpi nut goes over the thread I think it might be less than 1/2";-)

 

[MattF]

All fittings on Drummonds are standard form Whitworth, (BSW), unless a previous owner has made any additions or changes.

 

[normspanners]

from pic I plum for 7/16 Whit

 

[rtbcomp]

My Drummond has Whitworth screws on it too.

 

[steviec_lj]

Ummm

Upon measuring, the closest I can find is an 1/2" BSF. But it's not, as the TPI counts don't match.

I count 12TPI, which would make it an 1/2" BSW. But the Minor Diameter is 10.7mm, not 9.9mm.

At this rate, I'll end up nipping to BAPP, but then they're useless with anything Non-Standard, from what I've found anyway.

Any measuring tips?

 

[rtbcomp]

How are you measuring the minor diameter? Are you sure you're getting to the root of the thread? Don't forget that the thread is a spiral so you may not be measuring across a true diameter.

In spite of what you say, I would plump for a 1/2 Whit. thread.

 

[steviec_lj]

Possibly not getting to the root of the thread, my calipers may be resting on the shoulder as such.

Going to plump for 1/2 Whitworth and go from there.

Thanks

 

[MattF]

Just work from the major diameter and ignore the minor. One thing you'll find shedloads of with old threads are discrepancies, though Drummond were far more fastidious than most, (Herbert's are the worst I've come across upto just by far), but you'll generally find that you can set the die for loose fit, and some it will run down lovely and others it will flop around on. Thread cutting back in the day was prone to minor deviations. If it's reading within a gnats of 1/2" on outer, it's 1/2" BSW. If it's notably under, it's 7/16" BSW. The only deviation from BSW you'll ever generally find on a Drummond is the rear of the headstock spindle. Can't remember whether that's BSB or whatever offhand, but they went with a super fine thread on that with some.

 

[Wallace]

My money is on 1/2" BSW 12tpi.

 

[Rig Pig]

I would be amazed if it isn't whitworth from the look of the bolt

 

[Wallace]

I think your comment about the head size is another clue.

 

[MattF]

I would be amazed if it isn't whitworth from the look of the bolt

It is. It's one of those things which is pretty much a given fact, unless someone has altered things. Like Wallace and you both mentioned too, the head size is an instant giveaway also. You don't see meat like that on modern day or metric.