Chris

You're a legend, thanks mate.

I bought some sockets with the view of grinding one of them down to fit inside the recess of the slider, but the bolts are burred and seen better days. I will order some new ones. I tried metric, imperial and even my Whitworth and none seemed like a great fit.

As for the slider itself, it is slightly damaged at the threaded end where the slider extension screws in. It is going to be welded but then will require re-tapping the threads. The machinist was asking about the thread size and pitch. Better to know the correct size than guess when he sets up his lathe.

I get the 24 TPI, but 1.800? is that 1.8 inches?

Cheers

Al

Hi there Alun

1.8 inches is the same as 1.800 inches - that is 1 inch & point 800th of an inch

hope this makes it a bit more clearer if not drop me a line & I will try to help you

Cheers

Chris Moore

email (option): millspray@yahoo.com

For the purposes of expressing dimensions in this way the inches are divided into a thousand (thous.)...So 1.800" is one inch and 800 thousandths of an inch...Ian

email (option): ian@wright52.plus.com

The size is just not an inch and a tiny little bit, so I think, 1.8" is in decimal inches, so 45,72 mm. But I'll try to measure an NOS one tomorrow.

Lex

All good

The slider was welded and and the machinist used a modified old slider extension tube to cut the thread through the weld. Vapour blasted and looks like a new one. :slightly_smiling_face:

Good show, but what was the size???

So 1-13/16" just measured one, never use decimal inches on brit bikes, confuses the hell out of everyone.

Lex

1 13/16" is 1.8125". As you say Lex your old imperial measurement is probably more accurate.

While we're discussing measuring....Metric measurements for engineers are in mm! cm are for dressmakers.

Ron

email (option): ronpier@talk21.com

Based on the 'inch' system they are all Imperial measurements whether expressed as a fractional or decimal dimension (the latter originates from the word 'deccem' which is Roman for 10)...How something is dimensioned has some thinking behind it...'Standard' manufacturing practice would be that if a dimension is expressed as a fraction..eg. 1 1/4"..then the 'standard' tolerance applied would be + or - .015".(1/64").

When the same dimension is expressed as a decimal (1.250") the standard tolerance applied would be + or -.005"...So the finished part would be within the range of 1.245"- 1.255"...

These are general standard tolerances for manufacturing...If the same dimension needed to be more accurately produced for a particular application a 'closer' tolerance would be specified...eg. 1.250" +.002" -.000"...So the finished part would be within the range 1.250"- 1.252"

These tolerances have now become 'dated' with the introduction of CNC machines but in the home workshop or a non CNC environment they are still relevant...In those cases, if more than one component is being produced, a tolerance is always employed as it is impossible to manufacture consistently to exact dimensions manually...To achieve a very close tolerances a component may well have been initially machined on a lathe, for example, and then 'finish ground' to size on a grinding machine, a more accurate process...

The importance of considering tolerances when remaking parts and trying to correctly identify them is illustrated by the following...A spacer that fits over a 3/4" diameter wheel spindle may well have a .010" clearance and at that would function perfectly well...The same clearance between a 3/4" gearbox shaft and the bush that fits over it would probably be three or four times too large for correct function.....Ian

email (option): ian@wright52.plus.com

Thanks Ian, for the explanation, but where did you and others went wrong here? I saw it immediatly, as a fork slider of that small size would be only fit for a moped or a fairground attraction bike.

Ron, what dresses are you making now?? sometimes you worry me!

Lex

I don't know anything about the sizes of anything on a WD Matchless and I didn't even think about the sizes quoted...
My post was only to help (I hope) clear up the apparent confusion about how to express the measurements and to point out the thinking behind and purpose of tolerances ....Ian

email (option): ian@wright52.plus.com

What small size are you referring to Lex? The original poster quoted 1.8" which is nearly the same as the 1 13/16" you stated. Ron

email (option): ronpier@talk21.com

Just confirming please.

The bolts that screw into the sliders to secure the mudguard stays, part number 41-G3L-M38 (010795) are 5/16 bsf at 22tpi?

Cheers

Al

Mine are 5/16 Whitworth 18tpi. (Course thread for ally). Ron

email (option): ronpier@talk21.com

I just checked that, and they are in fact BSF! the bottom and top ones, 4 per slider.

Will get back on the other thing later tonight.

Cheers,

Lex

I haven't checked all mine. The one I took out is Whitworth so maybe a PO has modified the threads? Ron

email (option): ronpier@talk21.com

Checked 2 sliders, one NOS, and both have BSF.

So more like a POS changed yours!

Lex

I think you will find these bolts are all available from Steve Surbey at AMC Classic Spares. JT

email (option): wd.register@gmail.com

:laughing: :laughing:I see what you did there Jan ...The Metric system is efficient but dull...Whereas the wonderful Imperial measuring system (developed from the Winchester System of 1588), whether weights, volumes or measurements is so much more entertaining...Ian

email (option): ian@wright52.plus.com

Lex

Thanks, I just need to order a 5/16 22tpi tap now before my machinist does something silly and use an M8 tap.

Al

This worked a treat at re-cutting the thread section that was welded over.