T/C tapping on a 770
What spindle RPM are people using with the Tormach T/C tapping head (# 32020)? I'm mostly interested in using 2-56 and 4-40 spiral point taps in thru holes in 6061. I'd also like to try thread forming taps with the T/C head.
I've seen recommendations of 500 rpm. This is a problem on my 770 since I mostly use small cutters so I keep the mill in high range (525-10200 rpm). If I have to change belts it is faster to tap a couple of holes by hand!
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Re: T/C tapping on a 770
I use around 500 rpm on everything out of habit. My spindle is not calibrate very accurate and I see some tc extension and retraction but no big deal. I have 2 standard tc units with collets and 1 tc unit that uses the snap in and out tool holders. I see others use 1000 for their work. Just mod your feeds and speeds using std "1/pitch x rpms" or metric "pitch x rpms/ 25.4"Originally Posted by kstrauss
Cant say much about thread forming taps.
Re: T/C tapping on a 770
I've used my tc tapping head exactly two times with a 8-40 tap and haven't broken it yet
I used it at 500 rpm to . I can't see where a few rpm either way would make a difference .
Re: T/C tapping on a 770
On my 770 S3 I use YG-1 thread forming taps 8-32 and 10-32 in the TC head in aluminum (6160 and 7075). I think I've done 1/4 thread forming also.
Thread forming taps are awesome.
I havn't broken one yet, but I have followed the rules. Chamfer the drilled hole before tapping. Use a drop of moly dee in the holes on on the tap. Common sense says you want to give the form tap every advantage you can to both bite in and get started tapping and to tap easily once it does.
YG-1 has a thread forming drill tap chart (right hand gray column):
YG-1: BEST VALUE IN THE WORLD OF CUTTING TOOLS
But, I love using this Guhring chart for thread forming drills because you can select your thread engagement. It's in mm, but you can easily just look at a conversion chart and pick something close from inch drills. It really helps if you want a little less or a little more engagement for the form tap to keep it working reliably.
https://www.guhring.com/Support/Tech...Thread-Forming
Re: T/C tapping on a 770
For small threads (M2, M2.5, M3) I've had good results with thread mills rather than taps/forms.
I'm using Sandvik thread-specific mills https://amzn.to/3bhHOdH (there are two sellers on Amazon, one who charges full rate, and one who's reasonable but don't always have stock)
I'm using Micro 100 single-thread mills for more thread variation https://amzn.to/2yBT73k
Thread mills generally never break, and if they do, they just fall out through the hole because they don't depend on being wedged.
Fusion 360 has a good thread milling cycle, as long as you set the thread pitch, thread engagement, and lead-to-center options correctly.
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