Choice of Steel Grade?

Hi there, all,

I have to make a tee-bolt to hold a rear tool-post on my ML7. It's going to be tweaked-up pretty tight. I had intended to use some 3/8" diameter free-cutting (EN1a??) rod that I have in stock.

Then I remembered that, many, many years ago, during one of the early factory attachment periods of my sandwich course, I was in the trainee model-shop and had graduated to use of their ML7s. On starting one job, I found that the thread on the tool-post stud had stripped (not me, guv, honest!!!) and sought advice from the person in charge.

He had a look and then said 'Follow me.' and led me to the tool-stores (NOT the raw material stores) and asked for 'the KE9'. At least, I think it was KE9 but it was 60-ish years ago! Anyway, it was some very tough stuff.

So, before I could proceed with the routine trainee tasks, I had to perform this extra-curricular job of machining a new tool-post stud. Cutting the thread was a challenge but my efforts met with approval.

Now, here's my question - shall I be wasting my time if I make my tee-bolt from EN1a? Should I look for some tougher (and hence more difficult to machine) grade?

Is this a situation where perfection is the enemy of good enough?

A supplementary question: I've always assumed that the 'KE9' description, or whatever it was, denoted a product from Kaiser Steel, was I right?

Best regards,

Swarf, Mostly!

I know that some (many) will respond to this reply along the vein of "It is good practice to make the T-Bolts", but regardless here goes..........why waste all of that time making T-Bolts and messing about with the steel specification, when all you need to do is buy them ready made from RDG, ArcEuro Trade, etc, etc, etc. Get the bolts and nuts and then spend your time making something really useful like swarf, or some really difficult component for a model train or whatever.

The real trick with engineering, model or otherwise, is to not waste time re-inventing the wheel. Make use of the effort of others and focus on the real task in hand.

I agree with Swarf, and would also like to know. I have found it difficult to get the right length, size etc and have usually ended up spending more time modifying than if I had made my own from scratch. Currently trying to make longer adjustment studs for some toolholders that are short and I would like to know a better grade of steel.

Well you could go down to your local fixings supplier and get a 8.8grade M10 bolt and use the unthreaded shank from that to turn your stud from.

EN8 would be a reasonable compromise between strength and machinability, EN24 would be stronger but a bit harder to machine though does not need any special tools. Both these grades can be had from the ME suppliers in short lengths, they College or M-Machine.

J

Swarf, we used to use K&E steel, I can go back 50 years, and I believe the company was perhaps Kaiser and Ellison, and we used to get a tough tool steel, maybe oil hardening from them.

Chris Gunn

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I made a toolpost out of EN24 a while ago. It was nay-so-bad to work with and gave a reasonable finish. I threaded the ends with an M12 thread and used a tailstock die holder. It was 'doable' but a single point threading tool would be easier.

I am happy with the toolpost it's self. But the tool holder I used is made of metal with the strength of old cheese and has more movement in it than a New Orleans harlots hips when the US navy is in town. So on my shopping list for a future date is a 'decent' holder. So I will probably have to make another to fit that one.

Nick

Swarf (and others),

You might want to look at this page from West York Steel - it has all the names you will be missing!

**LINK**

Mark

Make it yourself.

If you haven't done such things for years, a nice big thread like that is a great way to get back into the swing of thread cutting, as the next job could be much more delicate, so the time isn't wasted.

Neil

Who has cheated and used rolled stainless studding for a toolpost stud in the past

Hi there, again, all,

Thank you all for your various inputs.

I've decided to take up Jason's suggestion and modify an M10 bolt but only as a temporary measure. (I prefer to keep my ML7 all Imperial as far as possible, just my personal preference.) I'll reduce the head to match the Myford tee-bolt head's shape. This will get the rear tool-post on-line soonest.

The thread I was going to cut on my 3/8" bar is 3/8" Whitworth, a nice deep one.  It's not the top-slide tool-post stud - that's 7/16".  That satisfies Neil's recommendation! (By the way, Neil, surely the tensile strength of stainless is less than that of mild steel??)  I'll screw-cut to rough the thread and then finish to profile with a die (if I can retrieve my box of BSW taps & dies from the workshop gremlins!!)

I haven't yet decided how to attach the tee-slot head to the 3/8" bar. Silver solder seems the favourite at present. And I might not use the EN1a.

Thanks again to all.

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 10/03/2015 22:03:02

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I think Jason was suggesting that you buy a long M10 bolt; cut off the threaded portion, and use the plain shank as raw material for your 3/8" Whitworth.

MichaelG.

Michael and Jason,

Oops! My mistake!!!!!!!!!!!!!!!!!!!!!!!

Best regards,

Swarf, Mostly!

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No problem

Here is a good indication of what's readily available.

... and the strengths of various grades.

MichaelG.

Edited By Michael Gilligan on 10/03/2015 23:04:14

Yes that was what I was thinking as M10 are readily available and can be skimmed down to 3/8" easy enough. Just get a long one that has a suitable length of unthreaded shank.

J

The yield strength of stainless depends on the exact composition, but should be about twice that of mild steel.

Neil

EN16T readily available, good manageability and also oil hardening, so it can also be used for simple tools etc.

editeed for spelking

Edited By Involute Curve on 11/03/2015 08:44:46

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Neil,

Interesting quote from my second link, above:

• Stainless steel fasteners do not exhibit a yield stress. In this case 0.2% proof stress is used instead, and can be defined as the tensile stress required for the component to exhibit elongation of 0.2%.

I don't know enough about Stainless Steel to comment ...

MichaelG.

I'm always collecting HT bolts of all sizes and any part that has to stand a lot of loads are made out of them.

Examples my pump drive shafts, propeller skeg shaft and many other parts.

Metric 10.9, 12.9 are my favorite or equivalent imperial grades.

There tough but have little trouble machining them with HSS as long as you are patient.

When using quality car exhaust valves for my steamer the head is roughed out with tipped tools then finished with very sharp HSS tools with good results.

Paul

If I was intending to bolt a rear tool post on a Myford and do it up tight ,I would be more worried about the load on the Tee slot and the risk of breaking the slot out. I suggest making a long tee nut ,to spread the load, tap it and use a stud made from a long bolt. Why does the nut require to be so tight,a shallow tenon would stop the toolpost rotating, Any stud material stronger than en8 would be a waste of material.

For my rear tool post, I used un speced mild steel, with the idea that if anything was going to break, it would be the thread in the T nut, rather than the T slot on the lathe.

Ian S C

Hi there, Nigel,

Thank you for your post.

The tool-post comprises two parts, a base and an upper block. These (proprietary) parts already exist. The base does indeed have 'a shallow tenon'. It (i.e. the base) is some 48 mm wide so the cross-slide tee-slots will be safely in compression, not bending.

The need for tension in the tee-bolt comes partly from the fact that the upper block is free to rotate on the base, i.e. it is not keyed or latched (like, for example, the 'Duplex' design). The block and base therefore need to be held together firmly to prevent the block rotating out of alignment once set up.

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 11/03/2015 13:59:36