PDA

View Full Version : OOPS, Solution, Cutting the Nuts Off



Paul Alciatore
06-22-2005, 12:42 PM
I have needed replacement Tee nuts for my Unimat for some time. The originals just do not hold up - soft steel and a bad design (turned, not milled).

I designed a better nut and bought some stock almost two years ago but other priorities...

Friday I needed four T nuts and only had three and two of those were like pretzles. So I dusted off the drawing, found the stock and started milling. I soon had four feet of T stock. Great!

I drilled 16 holes in one and used the center drill to mark the locations for cutting them apart at 3/4 " intervals. When I did the tap drill thing, I used a brand new 5mm drill that came with my metric tap set (M6 you know). It seemed a bit off and it did leave a raised edge on both sides of the hole but I deburred and pressed on. After tapping I looked at the threads and saw they were off center and only about 30% of a full thread. AAAaahhhggg! Oh well, I still had three feet of T stock left.

So I put it down for the weekend and came back to it last night. Inspiration! I had all the inbetween positions marked with a drill dimple for sawing.

The 5mm drill had unequal flutes. I have not encountered this in a factory fresh drill before except Asian imports so I was a bit surprised.

So I sharpened the drill and drilled the between hole locations. I carefully checked the diameter of the first hole and it was within two thousanths of the correct size. Great. Tapped again and inspected. All good threads.

Now I had to make two cuts between each nut to get rid of the old threads. But they were wide enough for this so the job is salvaged. I now have 15 new T nuts and three feet of T stock for more. And they work great. No bending when tightened.

The moral is if a drill seems a bit off, check it after one or two holes, not 16. Better yet, check all new tools first.

Just thought I would share.

Paul A.

WJHartson
06-23-2005, 12:10 AM
Paul, T nuts should not be tapped all the way through. If it is you can break out the top of the T slot when you tighten the bolt against the bottom of the slot. Tap the holes so that the stud will be tight at the bottom of the hole.

Joe

rangerod
06-23-2005, 12:25 AM
I had to check this thread out it kinda gave me the shudders. Glad it had nothing to do with what made me shudder : )

Allan Waterfall
06-23-2005, 08:31 AM
<font face="Verdana, Arial" size="2">Originally posted by WJHartson:
Paul, T nuts should not be tapped all the way through. If it is you can break out the top of the T slot when you tighten the bolt against the bottom of the slot. Tap the holes so that the stud will be tight at the bottom of the hole.

Joe</font>

I usually tap mine right through and peen the bottom thread over to stop the bolt going right through.

Allan

mrennie
06-23-2005, 09:10 AM
My initial thought looking at the title was that a vasectomy is alot easier.....

John Stevenson
06-23-2005, 09:57 AM
<font face="Verdana, Arial" size="2">Originally posted by mrennie:
My initial thought looking at the title was that a vasectomy is alot easier.....</font>


Might be easier but not nessesarily cost effective.
I had one done 28 years ago, it cost £28 UK pounds and works out to about £5.60 a jump................
Somebody asked why I didn't get a bit on the side..........I didn't even know they had moved it.......

[This message has been edited by John Stevenson (edited 06-23-2005).]

Paul Alciatore
06-23-2005, 12:26 PM
I am aware of normal Tee Nut construction. On the Unimat you generally use cap screws, cut to exact length to prevent hitting the bottom of the slot. So the OEM nuts were tapped through. I may upset the bottom threads on a few if I get some studs but for now I am following the original practice.

I may even Loctite some studs into a few nuts to form tee bolts. Now there's an idea and I have enough nuts now to make several lengths. Gotta buy some studs. What really started this was the failure of one of their original tee bolts that were supplied with the milling table. As I GENTLY tightened it - I DID NOT USE EXCESSIVE FORCE - the head came off. It was a press fit. Can you believe that? A tee bolt with a head that was just pressed on a stud. And don't tell me it just failed. Nothing ever fails with such a clean fracture. It was a press fit. Perhaps a shrink fit. Oh well, at least I have the CI bed, not aluminum or plastic.

In a fit of madness (or boredom) while cutting the nuts apart, I thought of the title for this post and then I just had to use it. Just having a little fun.

Paul A.

jackb
06-23-2005, 12:52 PM
For a minute I thought this thread might be refering to what to do with the kid who built the flame thrower. http://bbs.homeshopmachinist.net//biggrin.gif http://bbs.homeshopmachinist.net//biggrin.gif


Jack