Thumb screw material

[DalboyParticipant @dalboy]

I am repairing my Scribe block and have made the tilting lever as I have shown in another post.

I have looked in some of my books but can not find what steel would be suitable to make the thumb screw from it will have a 4mm thread on it can anyone suggest what to use and could someone suggest any books which will give an idea of materials for certain applications

[DalboyParticipant @dalboy]

[Jon LawesParticipant @jonlawes51698]

Will normal mild steel not cut the mustard? Nice and easy to thread and takes a nice knurl if required.

[JasonBModerator @jasonb]

A free cutting mild steel like EN1A or 230M07 in new money will turn thread an knurl easily

[Nick WheelerParticipant @nickwheeler]

Brass is perfectly adequate for a thumbscrew. Looks good too if that matters to you.

[Tony Pratt 1Participant @tonypratt1]

Mild steel

Tony

[VicParticipant @vic]

Either of those suggested would be fine but Brass might look nicer?

[DalboyParticipant @dalboy]

Thank you all I have tried hot rolled steel but at the slightest knock it just wants to bend. I have thought about brass as suggested it would look good and contrast with the steel. I did think of using some stainless steel which I have but until I try it will not know how well it machines.

I could use the existing thumb screw top and insert a 4mm threaded part of a bolt into it but would like to make it in one piece if for no other reason than to practice my machining.

[duncan webster 1Participant @duncanwebster1]

ot sure what you are describing as thumb screw, but if it's knurled I'd leave stainless alone. If it's what I'm imagining, a screw with a big knurled head, what I'd do is loctite a bit of capscrew into a knurled and tapped bit of MS or brass

[egaParticipant @ega]

Posted by duncan webster on 08/11/2021 21:33:39:

ot sure what you are describing as thumb screw, but if it's knurled I'd leave stainless alone. If it's what I'm imagining, a screw with a big knurled head, what I'd do is loctite a bit of capscrew into a knurled and tapped bit of MS or brass

Or drill an under-sized hole and press fit.

[Nick WheelerParticipant @nickwheeler]

Posted by Derek Lane on 08/11/2021 21:13:43:

I could use the existing thumb screw top and insert a 4mm threaded part of a bolt into it but would like to make it in one piece if for no other reason than to practice my machining.

I would only ever make knobs, thumbscrews etc by inserting a separate male thread into them. That's because it's quicker, easier, stronger and less wasteful of material.

Make one that way, and another in one piece and you'll see what I mean.

A length of decent quality studding in suitable sizes – M5/6/8 for me – should be in everybody's material stash.

[Bo’sunParticipant @bosun58570]

As long as Loctite (or similar) is strong enough, I like the idea of a separate threaded portion to save material, and for a nice looking piece, I'd use steel studding and a brass knob.

[Michael GilliganParticipant @michaelgilligan61133]

Please permit a slight digression, Derek

Having some background in Ergonomics, and being a frequent user of Microscopes [which tend to feature lots of twiddly screws!] … I would highly recommend using a straight knurl in preference to a diamond pattern.

MichaelG.

[Bob Unitt 1Participant @bobunitt1]

What a very medieval thread-title…

[Howard LewisParticipant @howardlewis46836]

The problem that I had with thumbscrews was breaking the "knob" portion from the thread when knurling.

My solution is to knurl the section closer to the chuck, and then turn down the outer portion to size ready to cut the thread.

In this way the knurled "knob" can be quite big in comparison to the thread diameter. (Say 12mm bar knurled, but with a M4 thread. ).

Howard

[John HaineParticipant @johnhaine32865]

A quick Google shows that ready-knurled stock can be bought.

[noel shelleyParticipant @noelshelley55608]

A 12.9 grade socket cap head with a press fit knurled head would look the part, I think ! Noel.

[Nick WheelerParticipant @nickwheeler]

Posted by noel shelley on 09/11/2021 10:14:22:

A 12.9 grade socket cap head with a press fit knurled head would look the part, I think ! Noel.

That's all the lock for my top slide is: the original screw with an aluminium head pressed over it. Well, hammered over it, as I didn't bother to remove the screw. I modified the carriage lock screw while I was at it. Now I can lock the slides without using a tool, which is how it should have been supplied.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Derek, I made these adjusting screws in two parts, which saved on machining and material, both parts were made from used parts, which was a couple of old hand nuts and a couple of spindles from worn out gate valves which were Loctited into the nuts.

These are used on my basic magnetic compass Compass which is virtually all made from used materials.

Regards Nick.

P.S. I hasten to say these are a lot larger than you need, but the principle is the same.

Edited By Nicholas Farr on 09/11/2021 10:56:25

[egaParticipant @ega]

Posted by Michael Gilligan on 09/11/2021 09:16:01:

Please permit a slight digression, Derek

Having some background in Ergonomics, and being a frequent user of Microscopes [which tend to feature lots of twiddly screws!] … I would highly recommend using a straight knurl in preference to a diamond pattern.

MichaelG.

I agree and prefer to reserve the diamond knurl for items which are going to be pushed or pulled. I do find straight knurling more predictable, however, and it does rather depend what knurls are already installed!

[egaParticipant @ega]

Posted by Nicholas Wheeler 1 on 09/11/2021 10:37:26:

Posted by noel shelley on 09/11/2021 10:14:22:

A 12.9 grade socket cap head with a press fit knurled head would look the part, I think ! Noel.

That's all the lock for my top slide is: the original screw with an aluminium head pressed over it. Well, hammered over it, as I didn't bother to remove the screw. I modified the carriage lock screw while I was at it. Now I can lock the slides without using a tool, which is how it should have been supplied.

GHT discussed your last point in his Manual, pointing out that the various improvements to his top slide could have been incorporated at the factory but probably at uneconomic cost.

[DalboyParticipant @dalboy]

OK I went for a two part construction I found a new bolt with the 4mm thread which was too long and I found a piece of brass rod about 2" long. I also had a single sided knurling tool which I only brought to add texture to some of my woodturning (I need to buy/make a better one).

Picture of the old and new screw

[Michael GilliganParticipant @michaelgilligan61133]

MichaelG.

[Jon LawesParticipant @jonlawes51698]

I like the idea of the two part construction; I also can't abide material waste. The finished part looks very nice.

[DalboyParticipant @dalboy]

All complete and back in commission

[Author]

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