What grade of steel to make Tee nuts for a 6″ faceplate?

[jon hill 3Participant @jonhill3]

Having restarted my fingerplate project, the 3″ square block x 1″ in hot rolled mild steel, I decided to face the short edges in the speed 10 with the 6″ faceplate. I made up some angle iron jaws, but then thought it would grip better with T nuts through the slots on the faceplate. So my question is what grade of steel would be suitable. I have some very soft steel, probably EN1Pb judging by how easly it can be dented and the pink paint code. Would this work or would a harder steel be less likly to distort when rotational forces applied?

[Clive Brown 1Participant @clivebrown1]

I’d say that your mild steel is perfectly adequate for the task.

[bernard towersParticipant @bernardtowers37738]

Definitely something like EN1a or similar Ive even got some in brass, If you squash any thing between the t nut and machine slot the nut is expendable not your precious machine

[John PurdyParticipant @johnpurdy78347]

For what it’s worth I have made and use a number of tee nuts for both the mill (7/16-14 thread) and for the lathe cross slide and vertical slide (1/4-28 thread) out of off cuts of aluminum sheet (probably 6061 T6). They have worked perfectly satisfactory  for the last 30+ years. Also been occasionally used on the faceplate. Have the advantage of being much easier and faster to machine and tap than steel.

John

[jon hill 3Participant @jonhill3]

Thanks for all the feed back guys.

John perhaps your right I have been spending a lot of time machining jigs and holding devices out of steel when perhaps softer materiels would do and be more efficient use of my time. Its just as well its not a comercial project or the customer would have a hefty bill!

However in the case of the Tee nuts and angle iron faceplate fixtures I will probably use them again. Its an interesting challenge machining steel on the mill at the edge of its capabilities.

[PeteParticipant @pete41194]

Besides the materials yield strength, there’s a bit more to it. Let’s say both the tee nut and bolt are mild steel. In rough terms, it’s generally accepted that the tee nuts or any threads depth would have to be at least one bolt diameter in length so those threads are in theory at least as strong as the male threads on the bolt. Since I’m not a mechanical engineer and whenever possible I’ll try and err on the side of caution and especially so for something like holding parts to your face plate and use at least 1 1/2 times or more of thread depth verses the bolt diameter I’m going to be using.

My Bridgeport clone uses the same tee nut sizes and 1/2″ diameter bolts and studs as a real Bridgeport would. There tee nuts have a thread depth in high quality and hardened steel of .630″ or 16 mm maximum depth. Commercial quality hold down sets for these machines will almost always have the last thread upset so the bolts or studs can’t exit through the tee nut and exert jacking forces against  the fairly fragile cast iron tee slots. At least my Teco brand hold down sets do. So there thread depth also agrees with that minimum of one bolt diameter thread depth.

 

[Mark RandParticipant @markrand96270]

Having made T nuts for my Myford ML7 out of mild steel, I found that it was fairly easy to strip the threads on them. Case hardening fixed the problem. I’d go for EN24T or EN16T as a result of this if not heat treating them, but maybe I’m ham-fisted.

[bernard towersParticipant @bernardtowers37738]

you must have bigger spanners than me Mark!

[Dave HalfordParticipant @davehalford22513]

Don’t forget to stop the thread before it comes out the bottom of the tee nut else you can end up jacking a chunk of tee slot out of the bed.

As Mark says above even Warco individual ones are made like this, Pound a pop.

[Mark Rand]

On Mark Rand Said:

Having made T nuts for my Myford ML7 out of mild steel, I found that it was fairly easy to strip the threads on them. … maybe I’m ham-fisted.

Yes, that’s a possibility!  I’d rather strip a T-nut thread than break a slot.

A colleague who’d been trained as an Army Combat Engineer on Bailey Bridges and other hefty kit, persistently stripped threads on computer equipment.  No matter what the reward or threat, he couldn’t stop himself, and had to be transferred to other work!   I also have a friend who, working on cars, insisted on tightening everything up by extending spanners with a length of pipe and/or bashing them with a hammer.  That he occasionally sheared a head off or broke a stud didn’t cure him.

I’ve made T-nuts out of Aluminium, and they work well enough.  The problem with them, and mild-steel, is they tend to deform and won’t last as long as the hardened steel version.   OK for light and moderate use though, and easily made when replacements are needed.

With enough clamps moderately tightened and positioned in all the right places, I don’t have work moving about, but what I do is relatively small.   Bigger work might well need more welly!

Dave

[Chris CrewParticipant @chriscrew66644]

Of course it should be commensurate with the size of machine, cutter and workpiece, but if the work won’t hold without much more than a firm ‘nip’ on the spanner, then it isn’t properly set up and clamped in the first place, IMO. I was somewhat surprised to read that anyone could strip a tee-nut, unless the thread had been very badly cut, because you shouldn’t need anywhere near that amount of force when clamping work. Resistance to a lightly clamped and delicate workpiece’s tendency to move can be increased by placing paper between the two surfaces. All my home-made tee-nuts and tee ended studs are mild steel.

[jaCK HobsonParticipant @jackhobson50760]

Less stiffness and lower yield strength can sometimes result in a stronger structure as they may help lessen peak loads. A mild steel thread is more likely to yield and spread the load across more threads than a hardened high-strength steel thread. Mild steel can accommodate a bit of yield before it is weakened; hardened and high strength materials are more likely to brittle fracture with minimal yield.

It also heavily depends on the tolerances. High tolerance would mean less strain is needed for more threads to engage.

[JasonBModerator @jasonb]

Of the ones I’ve made I have not even bothered to make them T section, just a bit of flat mild steel bar probably EN3 cut to a length longer than the width, drilled and tapped. So less depth of thread than a tee nut and not had a problem even on occasions when off the shelf threaded rod is used and that is often undersize.

[old martParticipant @oldmart]

We have made lots for both mills, rotary table and for a lathe faceplate. When you make your own, they can be a much better fit and longer also with a choice of different threads than you get with bought ones. My steel of choice is key steel which is slightly higher tensile than mild steel, but readily machinable. The most challenging ones I made were for holding the compound down to the cross slide on the Smart & Brown model A. They fit in a round dovetail groove and because there is not enough metal in them for tapping, they are one piece with the 5/16″BSF shanks. A custom tapered milling cutter was kindly made for us as the dovetail was not a common angle.

When you make the nuts, consider using metric threads as you can then easily buy fully threaded metre lengths and cut exactly the lengths to best suit every workpiece.

[Nigel Graham 2Participant @nigelgraham2]

For very delicate T-slots consider making a T-strip rather than single nuts. This is drilled and tapped with several holes, so it vaguely resembles a Meccano strip. Again, stake the end threads or use short threads on the studs so you can’t run the screw into the slot floor.

I did such especially, with just two holes in each of two strips, for my EW lathe’s vertical slide vice.

Material though: ordinary mild-steel is fine. High-tensile steel may be appropriate for commercial equipment used heavily every day, but if you strip a thread or break a stud on even EN1 fastenings you’ve been too hefty with it, to the point of risking damaging the machine or faceplate.

[John PurdyParticipant @johnpurdy78347]

Along the lines of what Nigel has said I have done that for GHT’s rear tool post and small rotary table for holding them on the Myford cross slide. Makes installation so much easier rather than trying to line up individual tee nuts. The ones on the rotary table, when done up tight provide a convenient way to hold it in the jaws of the milling vice with the underside of the base sitting on the top of the jaws. The two separate long ones were for a purpose long forgotten and the little short ones are for the tee slots in the rotary table.

All are from 6061-T6 aluminum. I have never, in 30 odd years, stripped one out or had a setup shift except for the one occasion where due to an “interrupted procedure” (the cause of probably 50% or more of aircraft accidents) I missed tightening up the nut on one stud.

John

[duncan webster 1Participant @duncanwebster1]

The original question was about tee nuts for a faceplate. I must admit that on the rare occasions I use a faceplate I just use ordinary nuts and bolts, don’t see the need for tee nuts.

Someone else suggested case hardening. It’s not easy to get Kasenit to go down a small female thread, and I’m not sure it’s a good idea anyway. Unless the hardening procedure lasts a long time, the depth of the surface hardened layer is very small, and so has little effect on the overall strength, and if you do get a deep case on a thin component (ie the section through a small thread), it will make it brittle. I suppose you could temper it, but a lot of fuss.

As others, I’ve made loads of tee nuts out of unidentified MS, never managed to strip one

[JasonBModerator @jasonb]

I’ve got a tee slotted faceplate so have to use tee nuts or previously mentioned flat nuts on that.

I also find that the tee nuts from my clamping set fit nicely in the through slots of both the 280’s faceplate and also my larger angle plates so they don’t turn when you are tightening the nut on the opposite end of the stud.

If you want them hard then make from gauge plate and harden those and temper them down so they ar enot too brittle which will also harden the threads.

[Nigel Graham 2Participant @nigelgraham2]

I don’t think they need be even case-hardened.

Though you could harden and temper ones made from gauge-plate, and that will slow wear, just how much use will these things have that wear will be a serious problem?

[HOWARDTParticipant @howardt]

A useful reference for component materials is the likes of WDS who list the actual materials used for parts.  When using a faceplate I would prefer to use high tensile tee bolts rather than seperate nuts.  with tee bolts you can see that they are fully engaged in the nut at the front and not have to worry that the stud has unscrewed from the hidden nut. We may be hobby engineers but the forces in action are the same for the job if it was in a professional environment.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, as old mart, I’ve also made them from key-steel, as I had a short length the correct width, to just mill each side to the slot width.

Also as JasonB, made flat ones, mine being black mild steel bar, which enabled a larger piece of threaded rod to be used in my mini mill slots, when clamping down anything with a wide slot.

I just staked these on one side with a dot punch in four places.

Regards Nick.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, the main thing about clamping down the workpiece, or a vice to a milling table, faceplate or anything else, is the clamping elements are not taking the machining forces, they should only need enough tension on them to produce enough friction between the workpiece and table / faceplate to resist the machining forces that will be applied to the workpiece, which, as mentioned, can be enhanced by using a piece of paper,  thin card or even thin gasket material, I like to use thin gasket material myself, as it will deform naturally into any small irregularities that may be present.

Regards Nick.

[JourneymanParticipant @journeyman]

Another method of making T-nuts is to use round bar as stock material. Drill & tap for stud in the lathe, just use a taper tap so the thread doesn’t go all the way through. Turn the spigot and part off. Bring the item to the correct width for the slot in the mill.

Quite effective method although probably not as quick as carving from rectangular and definitely slower than just using flat bar. These are to hold a toolpost onto WM250 lathe.

John

[Journeyman]

Yes thats the standard pattern you get from sherline

On Journeyman Said:

Another method of making T-nuts is to use round bar as stock material. Drill & tap for stud in the lathe, just use a taper tap so the thread doesn’t go all the way through. Turn the spigot and part off. Bring the item to the correct width for the slot in the mill.

Quite effective method although probably not as quick as carving from rectangular and definitely slower than just using flat bar. These are to hold a toolpost onto WM250 lathe.

John

 

[old martParticipant @oldmart]

We have three faceplates for the Smart & brown model A, two 9″ and one 7″. One of the 9″ ones has plain slots at 45 degrees and the other started out with six tee slots and I added six plain slots of 8.2mm width.The 45 degree plain slotted one is a genuine S & B one from ebay and when I first fitted it and prepared to skim it square, I paused just long enough to check it with a DTI, and it ran within 0.0005″, so I saved myself the bother of cast iron dust everywhere. We made custom tee nuts for the tee slotted one after a bought length of part finished tee nut proved to be too loose a fit for it. The length of unused tee comes in useful as a lever for unscrewing the faceplate from the spindle. The 7″ one has six plain slots of 12mm width. We also have a 9″ for the atlas, originally with a Myford thread, but bored out and a 1 1/2″ centre added held on by six aircraft bolts, this has 6 plain slots. The Atlas could have a bigger faceplate, but 9″ was the biggest I could hold on the S & B when I turned it.

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