Help..Threads...

[Darren]

Hi,

I'm trying to find a couple or four replacement screws for my pillar drill.

I measure them as 3.18mm / 1/8 inch at 40tpi

But what thread? I've tried downloading some charts from the downloads section but nothing seems to be there? What happened to those?

Then comes finding a supplier.....I like Precision Technology Supplies www.pts-uk.com but can't see anything I recognise (not surprisingly for me)

Help.....are 1/8 CS screws so hard to find in the UK?

[Darren]

According to this chart I think I'm looking for BSW? But not certain at all......http://mdmetric.com/tech/tict.htm


Oh give me metric any day.....

[No1_sonuk]

5-40 UNC has a 1/8 inch major dia.  Might be that.  Not sure how to tell at that size.

http://www.gewinde-normen.de/en/unified-coarse-thread.html

[Darren]

Yes I see that in my chart too, maybe they are identical.....

But this is a 60's British product, I'm guessing we didn't use American threads?

[Bluechip]

Darren

That German site has a good few errors in it BTW. I gave up with it..

This one may help

http://www.watchman.dsl.pipex.com/thread.html

Download as an Exel and sort tpi col.

1/8 bsw is 40 tpi

Edit  not 5BA?  3.2mm x 43tpi ish. sorry for mixed standards


Dave BC

[bogstandard]

Darren,

1/8 X 40 is a standard Whitworth thread size.

I think that is the one you will require. I do have a tap and die set to make them if you get stuck.


John

[Darren]

Thanks Guys....it's deff looking like 1/8 BSW.

Can't find any though.....

John, I think I might as well buy a die and make some....as daft as it sounds for what what once a common size. I think single pointing may be a challenge at these diameters and pitch?

[Bluechip]

Yep, s-pointing would be. I once did some 3/16 BSF, 'cos 2bA had taken over as preferred thread, for a m/bike.

Took about 6 ft of steel to make 14 1" CH screws.  

Never again.

About 2 wks after I did the wretched things I found a supplier of 3/16" BSF Taps/ Dies ...

You may be made of sterner stuff tho ?

Dave BC

[Darren]

Sorry chaps but after you all took so much trouble to help me out I cheated...

I priced up a die with delivery, thought about the ongoing postage strikes currently in the UK and looked at the two screws I needed to make as I couldn't find anyone selling them......all in all it just wasn't worth the hassle, so this is what I did earlier.

The screws were for retaining a bearing cap on the belt pulley for my pillar drill. It's quite a large pulley with two roller bearings in it.

I decided to have a go at drilling two new holes and tapping for some 4mm screws I had to hand. Used the cap to locate the drill. Could have drilled the 1/8 holes but didn't just in case things went pear shaped.



To my surprise the pulley is made from cast iron, lovely should tap easily then I thought to myself.....

And it did.....



These are the screws I wanted to use. A little on the long side, quick snip and tidy up on the lathe sorted that out.



And here it is all fitted together......much easier than messing about with 1/8 screws.......

[John Hill]

Dont forget to stamp a little 'M' beside each screw so that whoever next takes it apart knows to use a metric screw driver.