Tee slots and vice clamping

[JimM]

Hi guys

I need some advice about the best way to clamp down my vice on the milling machine.

I have an old Elliott Juniormil which although it has a 28" x 7" table has ridiculously small tee slots, the narrowest part being only 5/16 wide.

I've knocked up some tee nuts but when used with the 1/4" studs they just don't look meaty enough to hold my 5" vice securely. I can see a couple of way round this but not sure what the best method would be from.....

1. Go with the 1/4" studs and just use a couple of larger washers to spread the load.

2. Use 5/16" studs but with flat nuts as opposed to T nuts. Problem with this is that there wouldn't be a whole lot of depth on the flat nut to thread into. The other option would be 5/16" Tee bolt, which would be OK for the vice  but I lose some flexibility when it comes to other clamping needs.

3. Use 3/8" studs with a flat nut - obviously I'd need to turn down the area where the narrow part of the t slot would be and would have to slide the assembly in as a whole from the end of the slot. Was thinking that the advantage of this over number 2 would be that the stud couldn't be pulled out of the slot.

So what would the collective wisdom suggest ??

Thanks

Jim

[tinkerer]

Can you use a bar across maybe three t nuts to spread the load? Just thinking outloud.

[andyf]

Can you widen the upper part of the slots a bit (an easy job - it is a milling machine, after all) to take T-nuts big enough at the top to thread 5/16"? I suppose this depends on whether the lower part of the slots is wide enough to accommodate a suitably wide base on the nuts.

I enlarged the slots on my Dore Westbury to accommodate commercial M10 nuts and studs sawn up from B&Q's cheap and nasty M10 studding, but I only had to widen by about 50 thou (25 thou each side of the slots).

Andy

[Stilldrillin]

I really don`t like machining machine tables! 

Many years ago, the mill on which I earned a living had 5/8" wide table slots. I always used 5/8whit studding.......

The neat fitting (EN24t) T nuts lasted many years with no problems, as the table T slot supported the nut.

I always ensured the studding was fully screwed in to the full depth of the nut.

Jim, I would buy 8mm T nuts, and machine them to a nice sliding fit in the table slots......  

David D

[DMIOM]

........I have an old Elliott Juniormil which although it has a 28" x 7" table has ridiculously small tee slots, the narrowest part being only 5/16 wide.......

Jim, to help make sensible suggestions - could you advise width of the actual slot as well (so we know how much might possibly be milled away) and how deep is the lip?  - or just post a C-o-C sketch?

[JimM]

Jim, to help make sensible suggestions - could you advise width of the actual slot as well (so we know how much might possibly be milled away) and how deep is the lip?  - or just post a C-o-C sketch?

Good point !

I've attached a C-o-C sketch of the T slot and dimensions. These were mainly taken from the T Nuts I made and represent a nice sliding fit. Not sure why I've suddenly switched to metric though 

Thansk for the help

Jim

[Jasonb]

2. Use 5/16" studs but with flat nuts as opposed to T nuts. Problem with this is that there wouldn't be a whole lot of depth on the flat nut to thread into. The other option would be 5/16" Tee bolt, which would be OK for the vice  but I lose some flexibility when it comes to other clamping needs.

For use with clamping bars etc you could put a stud connector (long nut) onto the 5/16 bolt and then screw whatever length of studding you need into this.

Jason

[seanacais]

Just in case anyone is interested, here are the dimension of the T-nuts that shipped with the X2 style mill.

Kevin

[DMIOM]

Jim,

since there is no great width to spare, if you tried to use a bigger thread you'ld have relatively little left either side of the threads - so my vote would be to go T-bolts - and if you wanted to make your own you could make them with relatively long heads, maybe even an inch? and then, as Jason says, use connector nuts for extra extension - or blue pills? ;-)

Dave

[andyf]

It strikes me that if you have been using a couple of bar clamps on 1/4" studs to secure work direct to the table, and it hasn't shifted under cutting forces, then nor should a vice held down with a couple of 1/4" studs be any more likely to shift. And with the flat underside of the vice on the table over each T nut, you should be able to clamp down tighter than you can with bar clamps, where there is always the worry of breaking out the top of the T slot.

Andy.

[jugs]

Hi Jim,
turn the vice upside down, (making sure the vice jaws are accurately aligned with the axis), mill 5/16" slot/s in base of vice, fit 5/16" key in slot (use m5 capheads), this will sit in the table tee slot & takes all the machining forces. you then only nead small hold-down bolts.

If the keys are a nice fit in tee slot the vice will always be accurate without clocking.