Moving vice on mill table....

Or to put it another way - how to stop my mill vice moving on the table.

Its a beast of a vice must weigh 20kg - its bolted down to the mill table with 12mm tee nuts, but it still slides along the table when I'm milling something.

I'm at a loss as to why - i can't physically move it when not under load but as soon as I make a cut it slides.

Must say its not all the time and it only moves a few mm but as you can imagine its a bit annoying.

Tips and tricks please.

I have never known this happen except when I forgot to tighten the nuts holding it down. I don't think the weight is relevant.

• Are the nuts tight enough?
• Is the base of the vice flat, or are there any burrs preventing close contact with the table surface (on the vice or the table)? Check with surface plate - use blue and or check for any rocking of the vice.
• Are you being too ambitious with your cuts?
• Can you move the vice if you tap the work hard with a hammer or is it just when milling?

If all else fails you could try the trick of a sheet of thick brown paper between the vice and table.

Are the bolts in the tee nuts bottoming on the slot try putting a washer under the head of the bolt.

You say bolts rather than studdiing? Are the bolts passing through the T-Nuts or bottoming on the nuts, preventing the t-nuts from being pulled tight. Always use studding, not bolts, because a bolt can break the table by jacking the slot.

Apart from the T-nuts not being pulled tight properly, are they too small, ie, not bearing fully across the top of the slot.

Dave

Edited By SillyOldDuffer on 06/08/2021 10:31:09

Are the tee nuts bottoming out slightly on the base of the vice? Some clamping kits have Tee nuts that are definitelyy a bit long in the leg of the Tee, it could be that when pulled up tight it grabs the vice a little but not fully.

As mentioned

The nuts might be tight but are the right surfaces being pulled together

Wow thanks for the prompt replies- I made the tee nuts myself to suit the slots in the table and yes they use studs not bolts.

I did consider that the base of the vice is locking with the top of the tee nut and this could be a possibility - the tee nut is pretty close to the top of the table - the Mill came with what looks like a modified bolt to act as a tees nut so I made new tee nuts to suit - it was fine with the ground down bolt but not very professional - I'll start by milling a few MM of the top of the tee nut and see how i go.

Now where did i put those old bolts....... !

If the mill is not complaining (noisy) when this happens I think I would go for hold down problems, but as somebody said previously are your cuts too ambitious and are the cutters sharp. Plus one for the paper but not thick.

I use the "wrong" system a lot with hex bolts, but they are made a specific length to fit properly

Tee nuts are not tapped fully all the way through. Use a taper tap and only allow the tap to cut a partial depth thread at the bottom, check that a stud tightens before passing out of the bottom. This will prevent you from jacking the tee nut up and locking it into the underside of the tee slot.

Thanks for the guidance - I made the tee nuts with a 10mm thread and turned the 12mm stud on one end the approx thickness of the tee nut to 10mm and threaded it - that way the stud will butt up to the tee nut when it reaches the change in thickness.

I'll have a look tonight and modify the tee nuts and see if this fixes the problem.

Hi Me, the T nuts touching the bottom of the vice would be the first thing I'd have looked at, it doesn't hurt for them to be 1mm or so below the table surface to insure they are gripping under the T slot flange.

Regards Nick.

I have tee nuts with studding screwed into them specifically for use with vises. The studding is locked into the tee nuts and is just underflush of the bottom of each tee nut. Using studding means that the nut will always tighten down and never hit the end of the thread. The length of studding is made to be lower than any work sitting in the vise.

Since you made the tee nuts yourself did you check they were below the table surface when pulled up against the upper surface (inside) of the slots? They may be below the table surface when resting on the bottom of the slots but that is not what needs checking.

Martin C

Good point, MC.

Or tap all the way through because it's easier and then upset the bottom of the thread with a centre-punch. Good opportunity for hammering.

Same reason as Howard explains - to prevent the stud screwing all the way through the T-nut and jacking accidentally.

Dave

It is a bit time consuming, but making tee nuts yourself that fit the slots better and are 50% longer than bought ones is well worth it. They will last a lifetime.

I have a Warco WM14 and the slots take the head of a 10mm bolt very nicely. I just slide the bolt in upside down and use the nuts and washer on the top of both vice and angle plate.

Seems to work very well. I do have a lot of home made tee nuts.

The other thing to check is the vice-bed interface, is the bottom of the vice flat and is there a bump or bit of swarf in the way.

Try the nuts first, they are an easy check. Poke a feeler gauge in.

While noting that RB is a bit late to the party (see first reply), I often use a bolt - but only where appropriate or needs must. Sometimes with sufficient washers to ensure compliance, sometimes screwed in firmly (then backed off by a couple or three threads) then using TWO spanners (or spanner and allen key) to tighten the nut for clamping purposes.

Using only studs should avoid beginners breaking out T-slots.

All my home-made T-nuts are staked, to prevent any bolt or stud threading through. I like the idea of only tapping at full depth part way though the nut, but a better method might be to make a completely blind thread with a ground off plug tap?

Bought-in T-nuts are (generally) better than those made in the workshop because they are hardened (case- or through-hardened?), but cheaper ones are not always sized optimally - deep threads are wanted, but also sufficient swarf clearance below the nut and with flanks as wide as the machine slots permit. Old mart is right about making your own - and paricularly about the length of some of them. I bought in a holding-down kit from Chronos originally but have made quite a lot of extras (both mills have the same width slot but different depths).

I like to see both ends of the T-nut under the item being secured, or under it and any out-board posts - that way it should be virtually impossible to break out a T-slot, however poor the table might be (as long as it is flat, of course).

I sometimes have as many as 14 T-nuts in use on my Centec - not all in use (they cannot be removed from the power feed end.🙁 ). The machine only has two slots and the RT is often in place at the other end. My slot cleaning tool does not get much use, but the vacuum cleaner does a good job.