T-Slot nuts for Hercus milling attachment

[jack620]

I need some T-slot nuts for my Hercus milling attachment, but I'm not having any luck sourcing them. They are 3/8" wide slots, but the horizontal part of the "T" is thinner than the T-nuts I'm finding for sale. The horizontal part of the T is 16.7mm wide x 5.7mm high. The 3/8" T-nuts I'm finding have a 1/4" (6.35mm) high horizontal part. I'm talking about dimension C in the following link:

T-Nuts.com - Machine T-Slot Nuts, Inch (3/8 to 3/4) (http://t-nuts.com/product_info.php?cPath=78&products_id=245)

I could always grind them down, but they are case hardened, so I'd rather not. Surely there are T-nuts that fit a Hercus? Does anyone know where I can get them?

[Michael G]

You may be better off making the slot slightly deeper. I did that on my drill press so I could use a standard sized nut.

Michael

[jack620]

I was hoping nobody would say that. :)

[Abratool]

Probably best to make some Tee Nuts.
Dont know if you have a mill but I machined mine,easy job.
Machine a long tee piece, drill & tap accordingly & cut off to short lengths.
Use threaded rod or make your own. The studs can be loctited into the tee nuts so they want rotate.
Bruce

[Abratool]

Just went & checked my set up.
Here is an alternative.
Just use a neat slide fitting flat plate in the bottom of the Tee. Then drill & tap 5/16" BSW
for the studs which are loctited or rivetted over, into the flat plates.
Works fine & the 5/16" studs are a clearance fit in the 3/8th" wide top section of the Tee Slot.
regards
Bruce

[jack620]

Hi Bruce,
My "mill" is the Hercus attachment, but I don't have any T-nuts. Catch 22!
Thanks for the tip. I have a 5/16" BSW tap. It looks like 16mmx5mm bar is available. I suppose I could make the plates then use them to mill up some proper T nuts.

Chris

[Greg Q]

I once read a tip to make tee nuts safe, but perhaps on such a thin tee nut it might not be suitable. Here goes:

Once you make up your nuts and thread the hole, invert the nut, place a bearing ball larger than the threaded hole resting on the hole and hammer it until the last thread is deformed closed. This will prevent inadvertent tee slot damage from a stud jacking the tee nut into the weak part of the slot.

Greg

[morrisman]

Hi Chris

When I got my mill/drill, I didn't have any T nuts at all . Harold Hall suggests making the first two nuts by hand , in order to get the mill in operation, so you can make more T nuts .

I made two of them by hand , hacksaw and filing . It isn't very hard to do

Mike

[jack620]

Thanks Greg
I've been doing a bit of Googling and it seems deforming the thread at the bottom of the T-nut is definitely the go.

Mike,
That sounds like a good plan. I also wonder whether I could secure a length of suitably sized MS in my 4 way toolpost and mill a length of T-bar out of it? With shims and the correct diameter end-mill I should be able to mill the correct amount of metal from each side. After milling one side I would flip the piece end for end and mill the other side. Then it's just a case of drill, tap and cut to size. Could that work?

Chris

[Michael G]

Another option for deforming the bottom of a T nut thread is to use the back (the rounded bit) of a ball pein hammer as a punch and hit it with a soft hammer/ mallet. Two hardened hammers together is a no-no as we all know.
You could try holding the bar stock in the tool post but if it over hangs it will flap about and maybe break something. The other important thing to do is watch your milling direction - most lathes have some backlash in the cross screw thread so what ever you do, don't 'climb mill' with your direction of feed.

Michael

[morrisman]

That sounds like a good plan. I also wonder whether I could secure a length of suitably sized MS in my 4 way toolpost and mill a length of T-bar out of it? With shims and the correct diameter end-mill I should be able to mill the correct amount of metal from each side. After milling one side I would flip the piece end for end and mill the other side. Then it's just a case of drill, tap and cut to size. Could that work?

Chris



Yes that might work OK but be careful . The piece of MS needs to be held very rigid otherwise the milling cutter will dig in and it will make a mess of the job. Take very light cuts . I did some basic milling with the Sheraton, I held the cutter in the 4 jaw chuck and dialed it in - it worked OK .

And yes , do what Michael G said, only do up cuts, into the piece , any excessive backlash in the cross slide will tend to make the cutter chatter .

Mike

[jack620]

most lathes have some backlash in the cross screw thread so what ever you do, don't 'climb mill' with your direction of feed.

My lathe has quite a bit of backlash in the cross slide nut. In that case I don't think my plan will work. To avoid a climbing cut I would have to mill the underside of the piece and I wouldn't be able to set the piece high enough to do that using the toolpost. Looks like I'll have to make a couple by hand.

Edit: On second thoughts, I can mill the top surface and feed the workpiece towards me.

Chris

[jack620]

Mike,
I'll shortly be ordering a MT4-ER40 collet chuck which will hopefully reduce any chatter to a minimum.

[pipeclay]

A collet chuck wont help with chatter in your case,corerect machining methods and ridgidity will though.
Is this one of the milling slides that have recently sold on ebay.

[Anorak Bob]

There is another simple way of dealing with hold down fixings for the slide. Forget the nuts and the piddly 5/16 " studs and make 3/8" tee bolts. It's dead easy to turn down some 5/8" square bar and cut a thread. The greatest advantage a bolt has over a nut is that you've removed the fear of the bolt engaging the bottom of the tee slot.

I will admit to using a piece of flat bar in my tee slots, tapped to suit the 5/16" cap screws I had holding my home made vice onto my homemade Hercus look-a-like slide. The slide has 3/4" x 1/4" x 3/8" tee slots, bigger than the real thing.

I used the same lightweight set up to fix the pretend vice onto my Hercus mill table before I bought a real vice.

BT

[unixbigot]

I had a similar problem - milling slide no nuts. I turned a set of nuts on a threaded mandrel; rectangular foot but circular tapped pillar. My slots are about the same size as yours.

[jack620]

It's dead easy to turn down some 5/8" square bar and cut a thread.

Hi Bob,
that sounds like the go- no milling required. Any particular grade of steel you recommend?

pipeclay,
yes I bought it off EBay.

Chris

[jack620]

I can get 16mm square bar in 1020 or S1214. Does anyone know which is better for bolts?

[pipeclay]

1020 will be fine,all the compound tee nuts and cross slide tee nuts I make are out of 1020.

[jack620]

Ok thanks, I'll grab some 1020.

[morrisman]

Something along the lines of these might work

MYFORD LATHE TEE NUTS / VERTICAL SLIDE / CROSS SLIDE ML7 SUPER 7 ML10 | eBay (http://www.ebay.co.uk/itm/MYFORD-LATHE-TEE-NUTS-VERTICAL-SLIDE-CROSS-SLIDE-ML7-SUPER-7-ML10-/120833688315?pt=UK_Home_Garden_PowerTools_SM&hash=item1c223fc2fb)

[jack620]

Thanks Mike, but I bought a length of 16x16 1020 today, so I'm going to have a crack at making some 3/8" T-bolts over the weekend.

[Big Shed]

They're not very hard to make

http://www.woodworkforums.com/f65/new-dm45-mill-129991/index5.html#post1273783

[jack620]

Nice. Now I'm motivated!

[jack620]

Made a couple of bolts this arvo. They came out pretty well. I'll make some more tomorrow while I'm on a roll.

[Ueee]

They look sweet!

As far as milling on the lathe and the ER40 collet goes, I'd have to say that it will hold the cutter more rigidly than the other options mentioned as it will keep the cutter closer to the bearings. The further away, the more any bearing movement gets multiplied.

[jack620]

I briefly tried a bit of milling today with a P&N 4 flute end mill held in the 3 jaw chuck. I got a bit ambitious with the depth of cut and the end mill walked out of the chuck about 2mm over the length of the cut. Hopefully you are right Ewan and the ER40 will overcome this problem. I ordered an ER40 collet chuck on eBay yesterday.

[Bryan]

You will need to make a drawbar for that. You did order one with a thread for a drawbar right? :)

[jack620]

Yes Bryan, it has a 16mm thread for the drawbar.