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| UNC threads outer diameter...??? |
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| Dean W:
Henning, follow the advice about putting a bevel or chamfer on the end of your metal stock, and about starting with the proper side of the die. If you are using a good die, it should have a split in the circumference. It may help to leave the die in your die-stock slightly loose, so that split can spread a bit. Once it is started, you can back off the die and tighten the die-stock screws to get to the proper thread depth on your work piece. If you are using a die nut (thread chaser) instead of a normal die, they can be hard to start, and they are also usually made of carbon steel, and often not very sharp. Getting a proper adjustable die is the only way to help that situation. At the diameter you have your piece right now, (6.22mm) it should be quite easy to thread. However, what Lew said about quality dies could be your problem. I've come across cheap far east dies that would not put a thread on undersized brass, much less steel of the correct diameter. A good die will thread that piece at full proper diameter with little trouble. Dean |
| Henning:
Wow! That was a lot of good advice very quickly! I'll try and sum up: 1. Die is the right way around :dremel: 2. Ends chamfered 3. Die is top-of-the-line (I'm a toolsnob extraordinaire, ESPECIALLY on cutting tools) Gühring 182 european style closed threading die. (Link: http://www.guhring.co.uk/pdfs/threading-tools/dies.pdf#page=2&zoom=100 ) 4. Part to be threaded has been measured and control measured several times! (Funnily enough :loco: ) Which leads me to believe it may well be a problem either with the Die or the material. I will measure the die and also try another piece to see if it's something to do with the material. Thanks all for your comments! :mmr: |
| tom osselton:
Not trying to be smart but are you turning clockwise or counterclockwise / lefthand thread? |
| bigmini:
--- Quote from: Henning on February 05, 2012, 06:31:46 AM ---Hi all! In an attempt to make a very simple threaded in both ends stud i have encountered a problem which has me somewhat confused. My question is; What diameter does the portion of the stud that is going to be threaded in 1/4"- 20 need to be? My engineering book says that for regular threads (this is no critical part) that the absolutely smallest diameter is 6,22mm. I have the portion of screw down to that but i still can't make the die start threading. Have i got the size wrong? Or is it a problem with material or die? Any help appreciated, it's been a "few" years since i had to make a UN- screw last time... --- End quote --- I had this exact problem with a cheap tap and die set. The taps were good for about one use. Never could get the dies to start no matter how much taper I put on the end. I gave up and they're all in my scrap steel box now, or have been used to make other tools. Bought a quality tapping set including the correct drills and have been happy (for internal threads at least) ever since. |
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