Hex Silver Steel/Tool Steel ??

Stop following the project and use your engineering skill to redesign it to available materials.

When actually needing a bit of hex as per the beginning of this thread just find an old Allen key in a car boot sale.

+1

I'd be tempted to donate the project book to a charity shop. Then I'd make a centre punch from silver steel, hardened and tempered as required. I can't see any real need for it to be hexagon, other than to stop it rolling away. In which case file a flat on it before hardening.

Andrew

The Classic eclipse centre punch has a square end so start with a piece of GFS or square tool steel and turn and knurl.

Mike

Just looked at mine and they are octagonal so that confirms what others have said about tool steel. Being octagonal surely makes it more comfortable in the hand?

Hi Guys well unless I've missed something high carbon hex steel is not easy to source in Uk especially in small quantities. So my options are;

1.Just use round in stead of hex.

2.Do it in mild steel just for the exercise

3. Find another project

4. Use an old suitable hex alum key after annealing

I am tempted to do it in mild steel as it is the practice that is paramount and therefore no real waste.

Regards

Chris

Another option as you are only going to be doing light punching would be to get some easily available 6mm or 1/4" hex mild steel and drill say a 4mm hole 25mm into the end and Loctite in some 4mm silver steel that has previously been turned to a point, hardened and tempered.

While you are at it make a matching dot punch which is used first to accurately place a small indent that can be pulled over to correct any drift before enlarging the mark with a centre punch.

This would still give you the practice with harder material, The hardening & tempering process as well as drilling holes. You would also have a usable tool at the end rather than a mild steel one that is no good to anyone.

Edited By JasonB on 21/08/2019 15:09:00

Edited By JasonB on 21/08/2019 15:21:07

Hi Jason, I already changed my mind from using mild steel. Now going the 6mm silver steel route for entire thing. Like your idea. But questions in relation to your method.

1. Why use silver steel for end piece would o1 be as hard when hardened? Can't see reason for silver steel other than needs to fit exactly into drilled hole.

2. Would loctite hold as it will be subjected to shock? Any recommendation as to which loctite??

Just got new (used for £15) book Table Top Machining by Joe Martin at face value really good.

Regards

Chris

I have made several punches from 1/4" hex screwdriver bits - the removable kind that fit into a hex-socket ratchet handle. The steel is of unknown composition, but can be annealed and then hardened and tempered similar to silver steel. I used old bits that had outlived their original purpose, but here in Canada you can buy a pack of 20 new for around $10 including some 3" and 6" long that work well for punches.

Edited By JasonB on 22/08/2019 07:11:59

Edited By JasonB on 22/08/2019 09:28:14

I think JasonB needs to edit the above reply again to correct an unfortunate spelling error.

Andrew

Thank's Andrew, I will go and correct it.

Just as well I did not use the American term of prick punch when I suggested also making a dot punch

Thanks guys and sorry about my still somewhat confusion as to Uk and American jargon but Jason is right I have I read amongst other things American books so some loss in translation at this stage inevitable. moving on to metals on EBAY I note hex bar is available as free cutting steel now I have looked up this and it means what it says but would I need to know what grade of free cutting it is and also if it is possible to harden such.

While I am highlighting my deficiencies also in the I use American book is a project requiring '5/16 - 24 x 0.75 long hex end bolt. Would i be right this is 5/16 thread but what does the 24 mean?

Regards

Chris

Ideally you want to know the grade, go with a seller  who says their 1/4" hex is at least EN1A. This would be very easy to machine but no good a as punch

You won't be able to harden EN1A to use as a punch, without knowing what the other "freecutting" metals are it is hard to say but probably not hardenable for this use.

Does this mean you are now going back to using mild steel?

The bolt will be a 5/16" UNF thread form with 24 threads per inch (tpi) as imperial fixings tend to use tpi and metric the pitch between each turn of the thread.

In the long term think about what system you want to use, not much point in spending out on UNF taps just for a project when you intend to work mostly in metric in the future, alter bolt spec to suit

Edited By JasonB on 22/08/2019 11:26:35

Personally I wouldn't buy basic stock material from Ebay. A free cutting steel is almost certainly a low carbon steel and may also contain lead. Low carbon steels cannot be hardened in the same way as silver steel or gauge plate. They can be case hardened, which increases the carbon content of a thin layer on the surface. Case hardening can give a very hard wear surface while leaving the core softer and more ductile. However, that's not really what you want for a centre punch. One regrind of the tip and you'll lose the hardened surface.

The 24 is tpi - threads per inch. A 5/16-24 thread is UNF, a US standard, UNified Fine. I'd use an M8 bolt instead. The M8 fine thread has a pitch of 1mm, so 25.4tpi which is a good match. However, metric fine screws are less widely available than metric coarse. If coarse or fine is not specified assume coarse. So I'd stick with M8 coarse which has a pitch of 1.25mm.

Andrew

That's a relief; does that mean I passed the test?

Am I correct in assuming that you're not an engineer? The question about tpi and UNF has no real meaning. There are many different thread standards, but a particular value of tpi says nothing about the standard being used. To describe a thread you need several bits of information. First the outside diameter and tpi, or pitch. You could also add the number of starts and LH or RH, but most commercial bolts will be single start and RH. There is also the thread form, which covers items like the included angle of the thread and details of the rounding or truncation of the crests and roots. Finally the standard used, such as UNC, UNF, BSW or BSP, if not implied by the context.

The unified system has four main categories, UNC (coarse), UNF (fine), UNEF (extra fine) and UNS (special). By far the most common are UNC and UNF. From a 1/4" and upwards the threads are specified by diameter and tpi. Below 1/4" the series are defined by numbers from 0, or 1, to 12 plus a tpi. I'm not going to do your homework for you, a search engine plus an appropriate search term will give you the details of the standard UNC and UNF threads.

I've no idea what material EN* is. You are correct that thru hardened means it is hardened through the volume rather than simply being a thin layer. Case hardening is one way of getting a thin but hard layer, but there are others, such as induction hardening. For instance the much mentioned EN19 is well suited to induction hardening.

Andrew

Christopher J , not sure which side of the pond you are but assuming Britain for small quantities of metals try M-machine metals **LINK** and click on the catalogue -- no connection other than a satisfied customer and there are several other companies offering a similar service.

Ebay metals may well be OK and i have purchased from there but i alway look at the company if possible otherwise you may not get what it says on the tin !

Might be an idea to add your location to your profile on the forum.

Regards John

I assume EN* is a typo for EN8.

I have used the source of EN1Apb hex that I linked to several times so you should be OK with them as you were after e-bay sources. M-machine as mentioned above also good but not ideal web shopping.