Tapping Options

[Doc_rot]

I have a Bridgeport Boss series 1 I recently complete a retrofit on. I'm starting to accumulate tooling and need to figure out what I'm doing for tapping.

I'm still very new to this cnc milling stuff so I'm still trying to figure this all out. As far I I can tell there are 3 options.

Thread milling
single point vs multi-point? is this only good or larger/shallow holes?


Tension/compression tapping
How does this work with the centroid programing? are there issues with the tap not going to the same depth every-time? Are there complications with tapping blind holes? Are there any brands/models I should look at?

Rigid tapping
This obviously requires a spindle encoder which i don't currently have. Has anyone come up with a way to mount an encoder to the spindle for this type of Bridgeport? It seems the spindle is only accessible at the very top where the vari-drive is. Is it worth the hassle to retrofit this over a tension/compression tapper?

[suntravel]

Encoder:

viewtopic.php?f=64&t=1944

Thread Milling:

Single point mills are cheaper and can mill threads with different pitch, but it takes more time

Multi point can only mill the pitch they are made for, but faster

Tapping with tension collets will work

https://cuttingtools.ceratizit.com/ie/e ... 80665.html

Safe and fast is a reversing Tapmatic

https://www.tapmatic.com/product_line_s ... heads.ydev

For single parts or small series I prefer rigid tapping or milling for larger threads.

Uwe

[Doc_rot]

Thanks for the reply.

I saw that thread on retrofitting an encoder when I was searching this site but unfortunately there are quite a few differences between the manual Bridgeport 2J head and this machine. There is no manual quill feed on this CNC machine so there is no provision to retrofit like in that thread. Would it be possible to put the encoder on the spindle hub somehow?

the tapmatic looks like a good option

[tblough]

You'll have to look at the exploded drawings for the head, but my guess is it uses a similar drive setup due to the backgear. The back gearing causes issues because the upper components of the spindle drivetrain run at the motor drive speed. The only thing exposed at the top that is guaranteed to run at spindle speed in high and low is the drawbar.