Floating reamer holder - who uses one, your experiences with the tool?

[aribert]

I acquired a couple of floating reamer holders in a lot of Morse taper extension reducers. At least, that is what someone told me when I described the tool - the socket (3MT) is spring loaded, has about 0.6 inch of travel and even when fully compressed, the socket still has a slight amount of radial play.

I was looking for tooling with 4MT male ends and these floating reamer holders were in the lot. I'm trying to get an idea if I should keep one for myself. I don't use reamers that much and this holder requires reamers with a 3MT (or an adapter that has a male 3MT). If you use a floating reamer holder, in what applications is it most useful? If you have never bothered to use one when reaming, please comment also. And if you have ever hacked one of these into something more useful to you, please respond also. Thanks.

[Doozer]

If you can't float the reamer,
float the part.

-D

[Illinoyance]

Floating reamer holders only allow radial float. A tap driver will have axial float. Sounds like you have a compression tap driver.

[J Tiers]

Just as a point of information, an example floating reamer holder for a turret lathe is the oval item at top center of this pic.



A more chunky shop made one that could have been made for a regular morse taper (but wasn't) is this. In both cases, the reamer goes in the hole in the front of the device, and moves radially by some amount possibly as much as 0.025" or so. You can see the small radial gap in this pic.

[DR]

I agree with Illinoyance , it sounds like you have a tap holder. The ones I have are both tension and compression. Their function is for tapping in machines that can't feed exactly at the tap pitch rate. The holder compensates by extending (tension) or shortening (compression) to match the tap's required feed rate. The spring mechanism inside is fairly weak so as not to cause shaving of the thread flanks.

[DR]

...................................... in what applications is it most useful? If you have never bothered to use one when reaming, please comment also. And if you have ever hacked one of these into something more useful to you, please respond also. Thanks.

I have a job coming up soon for a floating reamer holder. 6mm bore in cogged belt pulleys need to be reamed to 6.35mm (1/4"). I'll do this in the vertical mill by dialing in the pulley to the spindle center then let the reamer float to follow the original bore. Reamers having multiple cutting tips tend to balance themselves in a hole taking equal amounts off each side of the hole (as long as you're reaming a round hole that is).

The danger of not having a floating holder is if the bore is not exactly centered a rigid mounted reamer may not follow the existing bore.

Sometimes if you have a very long shank, small diameter reamer the reamer shank will flex enough to follow a bore without a floating holder, not a good thing to depend on though.

A downside of floating holders is they usually require a bushing to hold the reamer, as opposed to an adjustable method like a drill chuck.

[aribert]

Here are pics of one of the Scully Jones floating tool that I acquired. Second picture, my finger is partially compressing the spring loaded 3MT socket. In the 3rd pic, I have inserted a 3MT drill chuck arbor so that I could press against it to bottom the socket out and take a pic. Even fully compressed, there is still 0.005 to 0.010 inch (guessing) radial play in the socket to holder body. If it is a floating tap holder, I might use a small drill chuck with a 3MT arbor in the tool to be able to hold various sized tap diameters.

On my previous lathe - Clausing 5914 (12 inch swing) I would let the tailstock slide once the tap was engaged with the part being tapped for all but my smallest taps. On my current lathe I'm guessing the tailstock weights 80+ lbs so I am busy cranking the tailstock quill to be timed with the tap engagement.