Is there a fine pitch M6 set screw?

jasonrodman · Nov 10, 2015

Hi All -

I'm looking for a fine pitch metric set screw but am having trouble. Specifically an M6 x .75 or .5. All of my normal online resources like McMaster, Fastenal, Bold Depot, Grainger, etc. don't show a fine pitch M6 set screw.

Any leads would be greatly appreciated!

Regards,
Jason Rodman

jasonrodman · Nov 10, 2015

I just found Metric Multistandard Components Corp. in another thread. They have a nice selection of fine pitch set screws (M6 x .75) but of course they are not long enough at only 20mm. Ugh.

juergenwt · Nov 10, 2015

A M6x0.5 or x0.75 thread is in the books but................why would anybody use such a thing? One of the advantages for metric threads is the limitation on pitches. Do you have an existing internal thread that size? I doubt it very much. Most likely not metric.

jasonrodman · Nov 10, 2015

We are using the thread as an adjustment feature therefore would like a fine as pitch as possible for more fine tuning.

L Vanice · Nov 10, 2015

An adjustment feature probably does not require the hardness/strength of a stock set screw. You can purchase of make threaded rod and slot the end for a flat screwdriver or Loctite on a nut or knurled knob. In a non-metric country like the USA, 1/4-40 is a favorite adjustment thread because a 25 division index dial will read in .001 inch increments. If it has to be metric, a .5 mm pitch is a more convenient choice than .75 mm if you want an index dial. Some commercial designs use long socket head cap screws with the threads going all the way to the head for adjustable stops. You can extend the threads with a die or, if the volume is great, get the screw maker to do a custom screw.

Larry

billmac · Nov 10, 2015

jasonrodman said:
I'm looking for a fine pitch metric set screw but am having trouble. Specifically an M6 x .75 or .5.

Surely not this, all over again.

If you want a non-standard fine pitch then it is not an M6 set screw.

juergenwt · Nov 10, 2015

OK - I understand what you are saying. You are looking at a real "special". Can you re-engineer to use a "DIFFERENTIAL SCREW" for real fine adjustment? Just about any combination is possible. Like take an M6, drill and tap M3 in the front and use a standard M3 set screw on the other side to get 0.5mm/turn adjustment. Just an idea without knowing what your part looks like.

Clive603 · Nov 10, 2015

If imperial will do Thor Labs do 1/4" x80 up to 4" long and 1/4" x 100 up to 2" with knobs if needed. Also threaded bushes to loctite in as being easier than tapping. They also have the taps, including what they call M6 x 0.5 but no adjuster screws to go with it. Thought I'd bought 6 mm x 0.5 adjusters from them in the past but obviously wrong. Not cheap tho'.

May be worth talking to Kozak Micro Metric Fine Adjustment Screws and Bushings On Kozak Micro Adjusters who obviously make such things on a regular basis.

Clive

jasonrodman · Nov 10, 2015

billmac said:
Surely not this, all over again.

If you want a non-standard fine pitch then it is not an M6 set screw.

Not sure I follow.

jasonrodman · Nov 10, 2015

L Vanice said:
An adjustment feature probably does not require the hardness/strength of a stock set screw. You can purchase of make threaded rod and slot the end for a flat screwdriver or Loctite on a nut or knurled knob. In a non-metric country like the USA, 1/4-40 is a favorite adjustment thread because a 25 division index dial will read in .001 inch increments. If it has to be metric, a .5 mm pitch is a more convenient choice than .75 mm if you want an index dial. Some commercial designs use long socket head cap screws with the threads going all the way to the head for adjustable stops. You can extend the threads with a die or, if the volume is great, get the screw maker to do a custom screw.

Larry

The volume will be quite high, in the 10's of thousands. Ultimately we'd also like this to have a cone end, which adds another level of difficulty in finding OTS. We may indeed have to to with a custom screw.

Pete F · Nov 10, 2015

As Larry said, if it's an adjustment screw, it's convention (and good engineering) to use a thread pitch that makes sense in terms of how far you move per revolution. For example metric micrometers have a thread pitch of 0.5 mm. Using 0.75, 0.8, or similar wouldn't seem to make sense unless there's some mechanical ratio involved.

Sorry I can't say I've ever seen anything like that, certainly not in small sizes, but when searching be aware that "set screws" are called various different names around the world. They're often called "grub screws" down here for example. However if you have scope to change the design a little, I've seen this used reasonably often, where a tapped bushing is inserted in your part and an adjustment screw is used. It looks like these guys sell directly threaded alternatives too, just depending on how keen you are to thread a squillion fine pitch 6 mm threads!! The insert M10 x 1 is a very common fine pitch btw, so you won't have any difficulties there.

Adjustment Screws - Fine Adjustment Screws - Catalog - Opto-Mechanical Products - Standa

WHHJR · Nov 10, 2015

New inventor old wheel.... Use 1/4-40.

EPAIII · Nov 11, 2015

From the fourth page of an internet search:

https://cometkartsales.com/M6-x-.75mm-Set-Screw-for-Bearing-Fine-Thread.html

and the fifth page:

M6-.75 X 6 SET SCREW

I stopped at ten pages. But there were a lot more.

Have you considered how easy or difficult finding the tap will be? A quick check showed that McMaster has M6 x 1, M6 x 0.75, and M6 x 0.5. Nothing finer than that.

Winterfalke · Nov 11, 2015

jasonrodman said:
Not sure I follow.

There was just a thread on this not too long ago; if I recall correctly, the designation of 'M6' automatically implies coarse thread (x1mm) unless otherwise stated. Not positive, I don't get too much metric hardware, so I just glanced over it.

steve-l · Nov 11, 2015

Winterfalke said:
There was just a thread on this not too long ago; if I recall correctly, the designation of 'M6' automatically implies coarse thread (x1mm) unless otherwise stated. Not positive, I don't get too much metric hardware, so I just glanced over it.

The M designation depicts the ISO standard thread pitch for a given diameter. You will also note that generally, this standard pitch fits in between the US NC and NF standards. There are engineering reasons to use both fine and course thread pitches and in that light, I don't like using the metric ISO standards unless I must.

jasonrodman · Nov 12, 2015

EPAIII said:
From the fourth page of an internet search:

https://cometkartsales.com/M6-x-.75mm-Set-Screw-for-Bearing-Fine-Thread.html

and the fifth page:

M6-.75 X 6 SET SCREW

I stopped at ten pages. But there were a lot more.

Have you considered how easy or difficult finding the tap will be? A quick check showed that McMaster has M6 x 1, M6 x 0.75, and M6 x 0.5. Nothing finer than that.

Thanks for the search. Unfortunately these all look to be too short at only 6mm. I need 30-40mm in length! A tall order to ask so much of one OTS screw. I think we'll need to go custom. I find it somewhat odd that the taps seem to be readily available, as on McMaster, but the screws themselves are not.

jasonrodman · Nov 12, 2015

WHHJR said:
New inventor old wheel.... Use 1/4-40.

The rest of the machine is metric so there's a strong desire to keep this feature metric as well.

jasonrodman · Nov 12, 2015

Winterfalke said:
There was just a thread on this not too long ago; if I recall correctly, the designation of 'M6' automatically implies coarse thread (x1mm) unless otherwise stated. Not positive, I don't get too much metric hardware, so I just glanced over it.

It seems if this was the case then the fine thread spec would not use the "M" designation, which it does. Example - M6 x .75 or M6 x .5

Limy Sami · Nov 12, 2015

You say10's of thousands?

You're making life harder than need be, .........cut out the middle man and go straight to a multispindle screw machine co, tell em what you want and they'll be able to furnish you with everything you need.

IT'S WHAT THEY DO.

If you only want a few, go to Victor Machinery - Metalworking tools and supplies , and get the taps and dies you need - only a few bucks, ,some 6mm rod and 10 mm hex for locknuts if req'd and get em run up locally.

jasonrodman · Nov 12, 2015

Limy Sami said:
You say10's of thousands?

You're making life harder than need be, .........cut out the middle man and go straight to a multispindle screw machine co, tell em what you want and they'll be able to furnish you with everything you need.

IT'S WHAT THEY DO.

Yes, that's the long term plan of course. For now I'm just looking for 10 or so. I'm getting closer...

M6 x 40mm Cone Point Set / Grub Screws (DIN 914) - A2 Stainless Steel

Is there a fine pitch M6 set screw?

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