Source for Small Quantity of Specialised Screws

[savageseadog]

I need some 1/4"-40 UNS (not UNF) grub screws HT Steel or Stainless. Application an old sewing machine. Rather than buying from a sewing machine spares supplier I would rather have Allen hex head screws rather the original slotted type.
Does anyone know a supplier who would sell a few?

 

[jamie N]

In Inverness, we've this company. Perhaps near you there's a similar.
I've been there to get a single S/S bolt, and it's never been an issue to them, they just want to help.

 

[burgundyben]

HT or Stainless? Quite different?

 

[savageseadog]

Nothing on eBay by the way.

 

[Ian_Rob]

I’m always very satisfied with service I get from Accu. Accuracy. Delivered. | 500,000+ Components - Accu

 

[savageseadog]

HT or Stainless? Quite different?

Either. It won't matter for a sewing machine.

 

[wonkywinch]

I don't know if Namrick can help. I've bought all sorts of weird sizes from them in the past. Namrick Ltd

 

[rotrax]

What is the number of threads per inch?

I have a lot of experience with odd threads and AFAIK 1/4 Unified are only available in 20 tpi or 26 tpi.

20 tpi is very close to Whitworth, only the flank angle differs by a tiny amount.

No problem at all with 20 tpi.

Perhaps you have something different I am unaware of.

I have plenty in my workshop if it is 20 tpi.

 

[savageseadog]

Thanks for your interest.
I also failed to identify the thread last time I tried to. I previously thought it was UNF but there was no match.

Definitely 40 tpi.

UNS Unified National Thread

The machine, for sailmaking, is a converted Adler. The hook assembly and drive is actually Singer based. I think Singer sold some of its parts or ip to Adler in Germany for their machines, possibly as part of post war aid.

I thought I'd cracked the issue when I took the screws off the near identical assembly on a scrap Singer machine I have. They looked the same but the thread pitch was 32tpi.
My problem is that the slotted screw heads are very worn but need to be done up tightly, the screwdriver slips out of the slot.

 

[biscuit]

I use:
Nuts and Bolts, Screws, Fasteners and Hose Clips - Westfield Fasteners Ltd. Never had a problem

 

[ean_p]

I think that you may struggle to find these unfortunately, and that you may be better off buying a die and having some made in the material of your choice. An important consideration is how important is the tip of the grub screw. Does it require a 'point' in order to bite into a surface or are the originals of reduced diameter to locate into something or are they just flat. It the later then very open to being 'homemade' if the otherwise then that would be down to your skill set. As for 'socketed' ....
BAER cutting die UNS 1/4 x 40 - HSS

 

[savageseadog]

Yes the tip is a consideration. It's a rotating shaft with a bevel gear which drives a hook assembly. There is a flat in the shaft. There are two grub screws securing the bevel gear but one of them won't be on the flat and in any case for fine tuning the timing you are supposed to be able to adjust the position minutely. The current grub screws are dead flat at the ends but I don't know whether that's wear or not. The machine is quite old, the design is probably post war and the machine itself is probably 40+ years old.
The issue is that a jam can cause the gear to slip on the shaft if not we'll secured. The screws need to be right. They've been loosened and tightened so many times the heads have been worn out.