[MichaelHenry]

I tried forming taps on Delrin but found cutting taps work better on Delrin material. Also use cutting taps on Turcite X & Turcite A. The taps work best if really sharp so only use that particular cutting tap on plastic only. For thru holes a HSS 3 flute spiral point gun tap works best for me on Delrin and Turcite. Gun taps have plenty of clearance for stringy plasic chips.

Don

Thanks Don. I've used a form tap on HDPE for a blind hole and that worked OK with manual tapping. You can feel your way with manual tapping and I suspected that CNC tapping might not work as well. Then too, it seems like formed threads could relax and change dimension quite a bit.

Mike

[Don Clement]

Thanks Don. I've used a form tap on HDPE for a blind hole and that worked OK with manual tapping. You can feel your way with manual tapping and I suspected that CNC tapping might not work as well. Then too, it seems like formed threads could relax and change dimension quite a bit.

Mike

I think you are right the Delrin material springs back after using a forming tap. Forming tap works great on aluminum though.

Don

[dirtridn2010]

I think you are right the Delrin material springs back after using a forming tap. Forming tap works great on aluminum though.

Don

I'm not sure if it has been mentioned yet (i did not read every post in this forum) but there are a couple of other issues that need considering. The limiting factor on these small machines is the power available at the spindle. Thread forming uses more power. So you may be able to get away with, say, 1/4" but stall at 5/16".
The other issue is the flow characteristics of the material. Yes you do drill a larger hole than if you are cutting a thread, but you still use more power too.
Some grades of Aluminium flow very well (remember we are moving the material around), and other don't flow very well at all. A lot of the steel that I buy because it is in my price range is Chinese and it is not the same quality (or specification) as others. We even have trouble cutting some threads with single point tools, let alone form a thread in these materials. And it is very important to use Cutting oil too, as opposed to coolant, which doesn't work as well. When forming, it is very important that the material flows well, or it is likely to have tiny cracks that will affect the strength of the thread.

[Don Clement]

I'm not sure if it has been mentioned yet (i did not read every post in this forum) but there are a couple of other issues that need considering. The limiting factor on these small machines is the power available at the spindle. Thread forming uses more power. So you may be able to get away with, say, 1/4" but stall at 5/16".

On my Procunier 1E tapping head there is an upper limit of #10 for form taps in Aluminum. I tap mostly 6061-T6 with excellent results using form taps. For threading larger than 1/4" or M6 I would thread mill and then power is not an issue. Here is a video showing thread milling 102mm-1mm in 6061-T6 aluminum on my Tormach. http://s72.photobucket.com/albums/i1...t=100_1311.mp4 BTW aluminum I buy is American not Chinese.

Don

Yeah Chinese metals are not always good quality. Allen wrenches are a good example. The only ones I have found nowadays that are any good are USA Bondus or German Wiha. I do have some 40 year old Hunter Allen wrenches (made in Riverside, California) that are even better. All the Chinese Allen wrenches I found were just junk no matter what the price. Sometimes one gets exactly what they pay for.