Tool Post Creep

[Foozer]

From the post about the V-block drilling jig found http://www.homemodelenginemachinist.com/index.php?topic=5077 I decided to try a solution to a problem of QCTP creep that I get on this little lathe. The holder came with a 1/4 inch bolt as its method to secure it to the cross slide. Got to thinking about the bolt vs. stud & nut combo so re-purposed a failed crank shaft and with a little bit of resizing made a stud as the tools hold down. New size of hold down is 0.375 inch over the original 0.250. Requires much less torque on the nut to achieve a positive result. Thinking that the length of the original bolt allowed for much to much twist reducing its holding capacity. Now, its just a quick turn of the nut and its tight.

Quick, simple and hopefully decent solution.

 

[kvom]

A nut with a flange that presses over a larger surface are at the top would be helpful as well.

 

[Foozer]

A nut with a flange that presses over a larger surface are at the top would be helpful as well.

Point taken, the piece of oops'd crankshaft was just long enough to knock out what I did. I do, now that I assured my self it does improve the case work on version 2 incorporating your idea Thanks

 

[AlanHaisley]

You might try cutting a relief circle a few thousandths deep in the center part on the bottom of the holder. That will concentrate more holding force to the periphery of the holder and should improve things also.

Alan

 

[Foozer]

You might try cutting a relief circle a few thousandths deep in the center part on the bottom of the holder. That will concentrate more holding force to the periphery of the holder and should improve things also.

Alan

Version 2-A Was out starting to cut a new stud for the holder, didnt notice any creep. Guess the QC are useful but have found that when I need something on size using the old rocker post does a better job. The "Newbie" in me, Ya, that QCTP looks cool, I better get one, it'll make me better. . . yup right here folks

 

[RobasaurusRex]

A very effective and easy way to prevent the tool post from turning / creeping is to put a piece of paper underneath it.

I have been using this method for a couple of years now and I've never had a problem.

 

[Stan]

All the QCTPs that I have used (not very many) had a rectangular bar as the head of the hold down bolt. The bar distributes the forces on the slot on the compound and provides a lot more clamp area. Your new bolt will have very little contact area in the slot, so a small clamp area.

 

[Foozer]

All the QCTPs that I have used (not very many) had a rectangular bar as the head of the hold down bolt. The bar distributes the forces on the slot on the compound and provides a lot more clamp area. Your new bolt will have very little contact area in the slot, so a small clamp area.

Version 2a is ending up to be a 'T-Nut with a stud' for the compound, QCTP slips over and nut (flanged) to lock er down. Original method that came with the tool holder was a 1/4 inch bolt that used an aluminum disk in the compound. First thing I did with that "New Toy" was to add a heli-coil to the disk. Still had the 'too much torque being applied' feeling so down this road I went and you have caught me speeding

Do have a hunk of steel to whittle a T-Nut out of, no mill so its a saw and file job, I should finish it up before I round that next turn only to find myself wrapped around the tree.

Dont take it wrong, In this case Thanks for the Kick

Robert

 

[Stan]

Robert: The only advantage of a T nut is to get more thickness for threads with a stud. On lathes that have room for a piece of 1/4" flat bar there is no need to make a T nut. Another method would be to weld or silver solder the bolt into a flat bar. Making a T nut with a file just seems like too much work.

 

[Foozer]

Robert: The only advantage of a T nut is to get more thickness for threads with a stud. On lathes that have room for a piece of 1/4" flat bar there is no need to make a T nut. Another method would be to weld or silver solder the bolt into a flat bar. Making a T nut with a file just seems like too much work.

No "seems like to much work" about it, didn't take long for that piece to get flung into the neighbors yard. Piece of flat stock, 1/4 inch thick sized to fit the slot, hole drilled to accept the stud shaft. Bottom side of flat stock given a slight counter sink 50 thou or so, to accept the mating countersunk of the stud. Turning it down from a 1/2" ss bolt to 3/8" Dab of solder, gonna need the bigger heat for that, and it should resist pull out just fine.

Things I do to avoid cutting the grass.

Thanks for the tip

Robert

 

[Foozer]

Version 3 Final

With the suggestions taken and a couple of false starts, one including tossing a hunk of steel over the fence, the Hey wait a minute, where is that box? was heard. Got this box of 'bout 2 hundred 1/2 inch by 6 inch flanged stainless bolts I picked up somewhere for who knows what but they look cool reason and the solution was at hand.

Turned one down to 0.370, threaded it a bit, ground down the flange to fit the slide, topped with a flanged nut, and POOF!

Qtr turn and tool post is snug as a bug in a rug.