Author Topic: M4 "Nylock" Grubscrews....... (Read 7660 times)

Stilldrillin · « **on:** July 21, 2013, 05:48:01 AM »

Hi Chaps.

I need 1, or just a few more of M4 x 15mm, stiff thread grubscrews. The type with a nylon insert.

Can't seem to find a UK supplier.......

David D

awemawson · « **Reply #1 on:** July 21, 2013, 06:06:35 AM »

Would Loctite Thread Locker do the job? Comes in various grades, from 'never come apart' to 'a wee bit stiffer' !

andyf · « **Reply #2 on:** July 21, 2013, 06:07:47 AM »

Don't know a supplier, David, but have resorted to two tricks in the past:
1. Cross-drill grubscrew and insert a short length of plastic which sticks out a tiny bit each side. I used nylon(?) strimmer line. May not be practical with M4.
2. Wrap with PTFE tape from my box of plumbing sundries (aka my "recreate Noah's Flood kit").

Andy

Stilldrillin · « **Reply #3 on:** July 21, 2013, 06:24:31 AM »

Andrew, Andy.
Thanks for the ideas Chaps......

I'm needing to replace the central, gib grubscrew/ locknut combination on my minilathe, with a flush fitting screw. To clear a planned carriage lock knob.

Can't understand why none seem to be available.

David D

BillTodd · « **Reply #4 on:** July 21, 2013, 08:40:49 AM »

If you have the thread depth, then you could use a hardinge style double grub screw.

Hardinge use a short locking grub with a through hex hole (which is loosened before pushing the key through to the adjuster beneath).

Bill

tekfab · « **Reply #5 on:** July 21, 2013, 08:49:59 AM »

Or just 2 grubscrews, one locking the other ?

awemawson · « **Reply #6 on:** July 21, 2013, 09:24:48 AM »

But he needs to undo it to lock / unlock the top slide

tekfab · « **Reply #7 on:** July 21, 2013, 09:27:54 AM »

Sorry i thought it was the gib adjusting screw he wanted to replace ?

Stilldrillin · « **Reply #8 on:** July 21, 2013, 09:39:01 AM »

Thanks Chaps!

I might get away with two grubscrews..... The available total length, is around 12mm.

Looking at the (old)pic. (The toolpost is wound out, to show the available travel).
Between the two brass oil plugs, is a 6mm caphead screw, which operates the carriage lock. When the socket's not full of swarf......

I want to install a 15mm dia, knurled head. Drilled for a tommy bar, or permanent handle.
But, with toolpost in it's usual working position, the central gib adjusting screw, is over the lock screw position.......

If you can follow that!

David D

David Jupp · « **Reply #9 on:** July 21, 2013, 09:46:20 AM »

Could your replacement screw have a short 'stalk' (to clear the grub screw), with the knurled head on top? Or not enough room?

Stilldrillin · « **Reply #10 on:** July 21, 2013, 10:33:19 AM »

David.
I've already tried to work that idea. But, the head is then rather short........

Thanks for the double screw idea Chaps!

Just had a quick fumble, and finished with a working assembly! With 2mm protrusion....

Some more fine tuning, of my screw shortening technique will see it sorted!

Thanks All...... For the ideas.

David D

Lew_Merrick_PE · « **Reply #11 on:** July 21, 2013, 12:54:57 PM »

ND Industries makes a product called Vibra-Tite. It comes in two forms: solvent evaporation and bake-on. The solvent evaporation version is a goo you paint on the threads and allow to dry for 30 minutes or more. The bake-on variety is painted on, allowed to sit for at least 2 hours, and then baked at 250°F (225°C) until the part is uniformly heated, and then allowed to sit for at least 8 hours before use. It acts like a Nylok insert. The bake-on version survives operational temperatures of 400°F (200°C) quite nicely. You do need to thoroughly degrease the threads before applying.

This is my preferred thread locker when a screw needs to be repositionable or retorqueable. Enco, MSC, and Fastenal all have access to it (but it is rarely stocked due to distribution restrictions required by Henkel/Loctite -- a product line I go out of my way to avoid).

Stilldrillin · « **Reply #12 on:** July 25, 2013, 03:46:30 AM »

Thanks Lew.

I made an M4 chucking sleeve, and finished up with two screws Total, 11mm oal......

Then realised, they couldn't be locked together, as the inner screw can't be tightened against the gib strip.

Any road! Screwed in place. New lock screw installed........

Works well! Thanks Chaps......

David D

BillTodd · « **Reply #13 on:** July 25, 2013, 12:49:54 PM »

Quote

Then realised, they couldn't be locked together, as the inner screw can't be tightened against the gib strip

that's why hardinge's locking screw has a through hole - try shortening the lock screw until the key will pass through ~3mm

Stilldrillin · « **Reply #14 on:** July 25, 2013, 01:27:18 PM »

I follow you Bill......

But, both hexagons are the same a/f, at 2mm.

Unless I'm missing something!

David D

RussellT · « **Reply #15 on:** July 25, 2013, 02:32:11 PM »

Surely that's OK as long as they're not locked together. Back the lock screw off until the hexagons line up and then push the key in further. Tighten, then pull out to engage only the lock screw.

I have no experience of this idea - I'm just going on the description.

Russell

Stilldrillin · « **Reply #16 on:** July 25, 2013, 03:37:40 PM »

Russell.

The problem is, I mustn't tighten the main screw. As it will lock the gib to the slide.......
The screws are used to position the gib, in a sliding fit.

Tightening the lock screw, just turns the main screw further in.

I'll leave it, until/ if there's a problem. Then I'll have a go turning a recess around a new screw, and fitting a little O ring.

David D

unc1esteve · « **Reply #17 on:** July 25, 2013, 03:47:32 PM »

I had a similar problem.
I removed the slide and relocated
the grub screw positions so they cleared
the offending object. Added
one more screw for a total of four.
Plugged the center hole with a shorter screw.
But, you may not want to drill
through your cross slide.

Stilldrillin · « **Reply #18 on:** July 25, 2013, 03:58:04 PM »

Yes! that would solve the problem Steve.
But I prefer to take the "easy" way, if I can.........

Frankly, three screws have worked perfectly well for the past 8 years. And the present mod has notched up 2 days, no problem...

I wonder if I dreamt about grubscrews, with a longitudinal stiff strip?

David D

BillTodd · « **Reply #19 on:** July 25, 2013, 04:15:26 PM »

Russell has nailed it:-)

Just back the adjuster out a twelfth of a turn berfore locking.

One important note: the gibs must be prevented from sliding relative to the adjusting screws else they'll ride up the adjuster points and jam. It is better to have a flat/cylinderical end on the adjusters that fit into shallow pockets rather than the more usual point and counter sink.

andyf · « **Reply #20 on:** July 25, 2013, 04:32:53 PM »

Will you have to do the same with either of the other gib screws, David, or doesn't the cross slide travel far enough to make that a problem?

Andy

PS You could always drill/tap a vertical hole (M3?) down through the cross slide and use a brass grub screw to lock the gib adjuster in place.

Stilldrillin · « **Reply #21 on:** July 25, 2013, 06:05:39 PM »

Bill.
Yer right! Russell has nailed it! I should have read closer wot he wrote......

Quite easy, when the penny finally drops......

Lock the two together, until flats line up. Then back out both, for correct tension. Simples!

Sorry for misunderstanding, Russell.

Bill. The gibs moved, when new. So, I made a "drill point" angle on the screws. Never had any problem since with either of the mills, or the lathe.

Andy.
The other screws are clear.
I haven't extended the cross slide travel, yet. As the repositioned toolpost copes with larger diameter work.

Good thinking on the vertical screw!

David D

RussellT · « **Reply #22 on:** July 26, 2013, 07:43:05 AM »

Hi David / Bill

I'm not sure I had nailed it as I hadn't spotted the problem of the two rotating together when you were trying to tighten only the lock screw

.

But I'm glad you've solved it and the carriage lock looks neat

.

Russell

News:

Author Topic: M4 "Nylock" Grubscrews....... (Read 7660 times)