Need a floating taphead
I'm tapping some 0-80 holes in 17-4 SS. I would like to make what I would call a "Floating taphead".
I want to avoid the 0-80 tap pulling or pushing my lathe tailstock. What I would like to do is start the tap
with spring pressure and retract the tap with spring pressure also. The lathe tailstock will simply keep the
tap from rotating.
Seems like I saw a setup like this for CNC mill tapping. Does this item have a name? Is it possible to make one of these?
Need some design ideas. I'm afraid I'm going to be engineering this thing in my sleep tonight unless I find a solution before bedtime.
Be careful with spring pressure, the entry of the thread can get pulled out on the retract if your spring is too strong.
If you're doing this in a manual lathe, how about one of these tap guides,
I have a home made version that's a ¼" drill chuck that floats on a dowel pin;
Machine Hand Tap Guide - Tap Guides | MSCDirect.com
Mari Tool has thier straight shanked floating tapping heads but I dont think they have enough travel for what you are wanting to do.
Straight Shank Tool Holders ER11, ER16, ER20, ER25, ER32, ER40 - MariTool
Have you though of using one of those little floating drill chucks?
How does the tap guide work. My guess is the guide does not permit the tap to rotate. Hand pressure starts and retracts the tap instead of springs, right or wrong?
That item is on track with my thoughts. Maybe I'll forget about the springs.
I tapped 4 parts and broke 2 taps worth $17 each and scrapped two expensive parts today.
I use a simple free rotating and sliding sleeve mounted chuck, light finger and thumb grip pressure is enough to stop the tap rotating and provides ''feel'' for the job.
The MSC tap guide is free floating, if you let go, the tap will spin with the part. The jaws have 2 steps so you can hold different size squares. I just tried putting a 0-80 tap in my MSC tap guide and the runout is pretty bad. I wouldn't get one for your application.
Here are a couple of pictures of my homebrew drill chuck. It works much better than the MSC tool. It floats on a 3/8" dowel pin;
I was at a shop today that has a Mazak Integrex and he uses an ERI America tension/compression holder. The shop bought the tool from me and the operator said it works great. One thing to keep in mind is keeping a sharp tap in it. If the tool dulls it will cause more tool pressure and may result in a cross-thread on retract.
Can I assume you grip the knurled ring with your hand to tap the hole? Does the chuck itself slide along the 3/8 dowel while tapping?
That would be a great idea. If the tap had a problem in the hole you could let go of the ring allowing the tap to rotate avoiding breakage. Nice simple yet effective concept. Jim
That's right, you grip the knurled ring. The chuck is mounted to a flanged shaft and the flange is screwed into the knurled ring with the three button head screws which are visible in the picture. The hub extending from the knurled ring has a reamed hole going through to slide on the dowel pin. The problem with the MSC tap guide is that you are only gripping the square on the tap shank. That doesn't hold the tap very straight. It works ok for larger taps because they can be pulled into the hole but smaller taps are too fragile and need to be held straight to prevent any side load. My drill chuck grips the full length of the tap shank and maintains alignment very well.
I think I have you concept copied.
The chuck arbor has a 3/8 bored hole. The chuck is free to both rotate and slide left and right. Plenty of left and right travel. My hand grip will start the thread, hold the tap and retract the tap when done. Probably should of made one of these years ago.
Below is a picture showing the chuck. Years ago a friend gave me the old Jacob #8 chuck. I rebuilt the chuck and replaced the jaws then never used it. Now I'll put the old chuck to good use.
Now I'm ready to tap some 0-80 holes. Thanks Jim
For small holes like that I use a floating drill chuck. It is spring loaded and I believe it's called a sensitive feed drill chuck or something like that. It's basically an albrecht keyless drill chuck with a spring loaded arbor and a knurled ring you can use to feed the drill. It's really designed for extremely small drills, but works great as a small tap holder.
But, unless I am not seeing the design correctly there is no power delivered from the spindle to the tap (or drill). The power is soley supplied by your fingers. And for very small taps that is enough.
Originally Posted by JimGlass
See my thought above which might be incorrect.
Originally Posted by Gordon Long
I think the sensitive chuck is diffferent in that it transmits power from the spindle to the tap.
Originally Posted by steverino
I hope Gordon can clarify this. Does your design transmit power or rather mainly serve as guide? If it does provide power, could you provide an assembly view? I guess I do not quite understand if it is only a guide why the cap screws need to be there. Seems like that part could have been one piece unless this it was a matter of using such materials as were available.
The power is transmitted by holding the chuck. It's free to spin and float. I forgot to mention that the concentricity can be adjusted. If I slacken the three button head screws, I can shift the chuck to get it to run true. A one piece construction is totally fine if the chuck runs true. I got mine on eBay as it is.
I also use mine as a sensitive drill chuck in the lathe.
I rotate the chuck by hand in addition to the spindle turning the part I'm drilling. This seems to help keep the hole a little more true.
A few years back I also made a sensitive drilling attachment for the lathe.
Here's a link to that old post;
Sensitive Drilling Attachment for Lathe
I've got one of those too, must have drilled 000's of holes with it.
Floating taphead works great
Using the floating tap from Gordon Long works fantastic. I tapped (25) 0-80 holes using the same tap.
Thanks for all the great ideas.
Video of tap head working.
Opposite end 4-40 spiral flute tap
Last edited by JimGlass; 08-20-2012 at 10:34 AM.
Reason: show 4-40 tap
Thank you, Jim, for the follow up, good pictures and video. That all takes some time but it is a real plus when folks follow through and show how they solved their problem after getting input from the forum. That happens too infrequently. More often someone posts a question, there is a flurry of good responses and suggestions.......and...........nothing. So, good for you! And thanks.
Next I'm going to use Limy Simi's suggestion for drilling small holes with the floating chuck.
I may have another job comming up where I'll be tapping a bunch of 4-40 holes in the milling
machine. I may try the floating chuck on that job.