Floating vise build

[DavidR8]

In this thread I revealed my dislike of my drill press vise. I did a bunch of searching for batter options and came up somewhat empty. @trlvn posted a link to a vise build by Mr. Pete that caught my attention.
I watched the build series and decided to build one.
I have stock on it's way and the 1/2-10 Acme tandem tap arrived this week.

If you've never tapped an Acme thread it is not for the faint of heart.
The tap drill is 13/32" or .406". My tap has a minor diameter of you guessed it, .406. Needless to say the tap has to remove a lot of material.
My first attempt at tapping I couldn't get the tap to start no matter how hard I tried.

Tonight I made another attempt starting with a 29/64" (.453) I started the tap in the mill but had to move it to the vise and finish by hand.
Using my 12" Patience and Nicholson tap wrench I went at it. Definitely really tough going for the first part of the tap. I could see the tap twisting and I feared it might snap. Lots of Tap Magic and I made it through!

My plan is to start with a a 7/16-10 Acme tap on a 13/32 hole. This should clear away enough material to give me a good chance of tapping the hole and achieving the full thread depth.

 

[YYCHM]

What material are you making the nut out of ??

 

[DavidR8]

There isn't a nut, the moving jaw of the vise jaws is tapped for the 1/2-10 Acme thread. It slides along the rod on the left side.

 

[YYCHM]

Jeepers…. twisting a 1/2" tap Is adapting it for a brass nut an option? That would make it replaceable as well.

 

[kevin.decelles]

I hear ya on the pucker factor for tapping acme. The 1”-5 brass nut I did took an incredible amount of force, but it too worked out

Great work!


Sent from my iPhone using Tapatalk

 

[Darren]

Or a cast iron sleeve nut glued in. Cast taps like butter

 

[DavidR8]

I actually thought about buying a 1/2-10 Acme coupler nut from McMaster, turning it round, boring the jaw and pressing it in.
If I break the tap that's what I'll do.
https://www.mcmaster.com/93023A673/

@dfloen what's is a sleeve nut?

 

[YYCHM]

I tapped three 1/2-10 LH ACME brass nuts no problem at all. Twisting a 1/2" tap seems rather excessive.

 

[DavidR8]

I tapped three 1/2-10 LH ACME brass nuts no problem at all. Twisting a 1/2" tap seems rather excessive.

This is mild steel though.

 

[YYCHM]

This is mild steel though.

I hear you... What I want to know is how you got it started on you mill? All's I've accomplished so far trying to tap on my mill was to drill/mill an oversized hole

 

[DavidR8]

I hear you... What I want to know is how you got it started on you mill? All's I've accomplished trying to tap on my mill was to drill an oversized hole

I just chucked the tap in the Jacobs chuck, dialed the VFD frequency down to 22 hz and let it go. Got about two'ish turns in before if stopped.

 

[Darren]

I actually thought about buying a 1/2-10 Acme coupler nut from McMaster, turning it round, boring the jaw and pressing it in.
If I break the tap that's what I'll do.
https://www.mcmaster.com/93023A673/

@dfloen what's is a sleeve nut?

an internally threaded , nut that is round on the outside. Pretty easy if you find a small slug of cast iron. It really threads and machines nice.

 

[Darren]

When i am power tapping in the mill (hand tapping is for suckers ), I chuck the tap in the drill chuck snug, but not super tight, I'd rather a tap slip than break, and then run it in at like 100ish rpm, when it slips, back it out, tighten it up to get a feel, then run it in again, repeat as neccesary. lotsa oil. But acme taps need torque. I have er32 tap collets. They dont slip. They punch through or break taps. Find a happy medium. I'd run some test pieces first. If the tap drill is 406 and the root is 406, Godspeed. Can you single point it?

 

[Chipper5783]

For power tapping, go with a spiral tap- spiral point for chips forward, spiral flute for chips back, the cut with much less torque as there is more of a shearing action. Of course the chips don't pack in either. When hand tapping with one of the spiral taps it is amazing how much easier it goes.

I doubt spirals are an option for an Acme thread. Per the statement above , single point in the lathe (even just to rough it in, finish with the tap). Of course you could single point thread mill the Acme - sounds like all the justification needed for getting a CNC mill.

 

[DavidR8]

Unfortunately single pointing is not an option as my internal threading tool is 1/2” diameter so it’s too large to fit.

My plan is to start with a a 7/16-10 Acme tap on a 13/32 hole. This should clear away enough material to give me a good chance of tapping the hole and achieving the full thread depth.

 

[PeterT]

I've heard those taps can be tough sledding. Is it a photo parallax optical illusion - it almost seems like there are 2 stages of graduated taper? I dont know much about these but assumed it would be a single taper & then straight final thread size.

 

[DavidR8]

I've heard those taps can be tough sledding. Is it a photo parallax optical illusion - it almost seems like there are 2 stages of graduated taper? I dont know much about these but assumed it would be a single taper & then straight final thread size.

Your eyes are not playing tricks on you.
It’s a tandem tap. The first half roughs in the thread form, the second half finishes it.
I’ve read that acme taps come as roughers and finishers but I’ve never seen them for sale.

 

[CalgaryPT]

... I could see the tap twisting and I feared it might snap.

I know that exact feeling when you see the tap twist. Absolute terror.

 

[DavidR8]

Picked up the Acme rod this afternoon.
The test pieces that I drilled and tapped are an excellent fit.
This bodes well for my plan to drill to size, tap with a 7/16-10 Acme tap and follow with the 1/2-10 tap.

 

[DavidR8]

My 7/16-10 Acme tap arrived today.
Nothing left to do but the doing!