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Old 12-01-2017, 06:09 AM   #21
Naiveambition
 
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Adding some closure to this thread.

I was able to accomplish my threads but not without some complications and discoverys.
For this mission I switched to alum. The male thread went as planned but the female still presented issues. 1st being I found my leadscrew clamp was busted and with cuts under.01 it was fine but any more it would slip out of sync and kick the gearbox out of gear losing my place. So after fabing up another solved my issues there. The second issue was most likely cutter geometry. Was not cutting nice clean chips, more of a tear style chip. Under power it was enough to stop my little 7x10 so had to resort to hand turning the lathe and finally made it thru.

I chose 20 tpi and cut till I had one full turn on the dial or .1 I think.. Now granted I made my own 60* guage for setting the tool and prob made mistake of using small top rake. So not perfect but worked in the end will need some more practice but at least the steps are down and work on the finer points.

Here's a pic of my parts The iPad cam has no definition so they do look better than the photo.


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Old 12-04-2017, 03:04 PM   #22
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Glad you had some success, will leave others to comment on cutting geometry as grinding cutting tools isn’t one of my strong areas. But something is definetly wrong if it gouging and not cutting, my initial thought would be too deep a cut, without enough horse power (as alu can be gummy) but won’t comment past that as am only guessing without more details.

Anyway good luck with you project, thanks for the update.

Cheers,
Adrian


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Old 12-04-2017, 05:08 PM   #23
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Hi, From looking at your picture of the threads in the ring, make sure that the tool has enough clearance under the front and side edges. It looks as if it is rubbing and tearing the thread. I've had this problem with home ground tool bits. The problem gets worse with smaller holes. I have started to buy small carbide threading bits, which gets around this problem nicely. You still have to watch the hole size though.

HTH.
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Old 12-04-2017, 09:33 PM   #24
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Just throwing this out there, with regards to the comment of Ali been gummy, have you tried cutting Ali with WD40. It stops the Ali cold welding itself to the tip, which may be another cause of the dragging that you've experience. For the sake of a couple of quid for a tin may be worth a try.
?? It did wonders on a part that I was turning, plus the chips just rolled off the cutting tool.

I by no means profess to be an expert, this is just my observations from my own work.
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Old 12-06-2017, 01:58 PM   #25
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Quote:
Originally Posted by JCSteam View Post
Just throwing this out there, with regards to the comment of Ali been gummy, have you tried cutting Ali with WD40. It stops the Ali cold welding itself to the tip, which may be another cause of the dragging that you've experience. For the sake of a couple of quid for a tin may be worth a try.
?? It did wonders on a part that I was turning, plus the chips just rolled off the cutting tool.

I by no means profess to be an expert, this is just my observations from my own work.
I might have added a bit of confusion by bringing up the gummy alu comment. To clarify I was just trying to read between the lines with the OP comment that he wasn’t getting good chips and it was more tearing which to me might have appeared gummy.

But you point is extremely valid though, when I first started with alu I used wd40 and it works great. Now I use a fog buster as just run it generally set and forget after program proofing on the mill which is where I cut most of my alu, but yes coolant would be recommended when starting out. Although i have had quite a bit for success roughing dry.

The other thought I had was if it wasn’t any of the culprits that have been mentioned by any of the previous posts it could be non heat tread alu, which can be a bear to cut and might explain the tearing, in my experience you want T3 or T6 (common) alu in a 2011, 6061 or 7075.

I too am no expert, but always interested and keen to learn about cause and effect of stuff like cutters and material.

Cheers,
Adrian
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Old 12-06-2017, 02:46 PM   #26
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I'm sure that there are many cutting fluids available but if you want a 'home brew' try one part kerosene, one part Varsol and one part Automatic Transmission fluid.
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Old 12-06-2017, 03:50 PM   #27
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My experience is that any kind of light oil will work, penetrating oil bought at garage sales for a pittance works best as it soothes My wallet at the same time.


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