Floating Tap Holder.

[magicniner]

If your mill doesn't support rigid tapping is Thread Milling an option for you?

[jamesgates1000]

These pcm collets hold taps and are sprung loaded, they are available in the whole range of er sizes.

You can buy them from wnt but they are quite pricey, I found a few er25 on ebay that I use on my Denford triac. If you buy the largest diameter you can find you can make sleeves to hold smaller taps.

https://www.pcm.ch/en/products/tapping-collets

[jamesgates1000]

Cutwel also sell them if this is suitable for you...

https://www.cutwel.co.uk/tool-holdin...h-compensation

[Will_D]

Thanks James but have you seen the price!! Over 100 per tap size. There are tapping collets available (Standard ER collects with a squarenhole at end to fit specific taps) at about a quarter of the price. Trouble is the collet holders are not available in R8. Question still is how do springs allow the tap (held rigidly by the collet) to float in the holder.

They have to be able to float in all 3 axes but still apply torque to the tap?

How are these floating holder designed?

[magicniner]

They have to be able to float in all 3 axes but still apply torque to the tap?

No they don't.
Floating tap holders assume the machinist/CAD/CAM Monkey is competent enough to align X and Y and only float in Z, this is to prevent breakage when a machine's Z feed doesn't perfectly match the required movement for the tap to maintain neutral tension.
Floating reamer holder requirements differ

[Will_D]

Ah so! Thanks for clearing this up.

So I will bore out a blank R8 to fit a parrallel shank ER20 holder. Fit a drive pin and spring to bias the holder at 50% of the slot. Then use the square ER20 tapping collets.

Seems like a plan

[magicniner]

Sounds like a plan!
Ensure your materials are hard enough and well lubricated enough to avoid galling, making the pin square with soft corners and using a Moly lube on the sliding areas will help,
Regards,
Nick

[Will_D]

@magicniner: I am only tapping up to say M10 so no need to thread mill

[magicniner]

@magicniner: I am only tapping up to say M10 so no need to thread mill

I Thread Mill down to M3, some things I make require a full thread right down to a shoulder, this has internal and external full threads to shoulders.



Internal and large external are both 1mm pitch and so were cut with one thread mill, if you are only tapping bolt holes milling may be overkill but it also allows you to produce any class of thread with one tool, unlike taps. ;-)