It should be marked as per normal for other types of dies, if not you may need to try it on a screw of the thread type you wish to cut, if you use the test method you will need to be careful if it is an adjustable die.
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It should be marked as per normal for other types of dies, if not you may need to try it on a screw of the thread type you wish to cut, if you use the test method you will need to be careful if it is an adjustable die.
Hi Guys,
Actually I don't think I've ever seen an unmarked die !
Hi Martin
I must be missing something but the thread in the pic is (what looks like to be) a square thread. If so, you will need to make an ACME nut to suit the new screw as well.
Phil
Phil, you are missing something. I'm remaking the screw for the compound. There is nothing wrong with the existing nut.
As for the die, I assumed that it would marked with the size, but wondered what would identify it as a whitworth thread form as opposed to something else. I just did some google research and will look for a die marked bsw.
In any case I made the fatal mistake of deciding to just 'tidy up' and non functional shoulder on the finished part. Should have left well enough alone. I turned and bumped my cross slide and the part snapped. D'oh!
I now have a scrap part to practice my acme threading on.
Martin https://uploads.tapatalk-cdn.com/201...e22b36af2b.jpg
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oops !
As a slightly related diversion, how did y'all actually remove the screw?
- The SouthBend refurb manual says there is a pin spanner hole, just like the cross feed screw.
- My Hercus compound screw doesn't actually have any such hole!!!Attachment 382289Attachment 382290
(the thing that looks like a hole is a set screw for locking the graduated collar onto the shaft)
Use something to protect the dial and grab with vice grips or similar and give it a turn, you may need to hold it in a vice, once you crack it ,unscrew it.It should not be overly tight.
You may want to remove the nut , handle and woodruff key first, if it hasn't got a woodruff key it may have a small round pin.
[QUOTE=m.j.bower.69;1955228]I got a bit of quality shed time in last night and managed to knock up a copy of the feed screw for threading. Had to sharpen the cold chisel a couple of times. I'll probably try a test run on another shaft before I tackle this one.
hi mate .have i missed something. ?? is the cold chisel sharpening. part of another story???
The cold chisel comment was a joke. Clearly not a good one...
In other news I finally got a good thread on my 4th practice run, so set up my blank and started in.
I've knocked up a mandrel based handle for the spindle so that I can roll the carriage back after each pass, which made it a LOT easier.
Unfortunately I must not have tightened the chuck properly abs halfway through the thread looked a bit NQR.
Turns out the blank had been pushed back a smidge in the chuck. Just enough to bugger up my thread.
This project has been interesting, and I've learned a lot about the importance of the order of operations. Not always obvious when you start.
I've also learned how little I use the compound. I've hardly missed having it operational. Maybe I'll go the full Gotteswinter after I'm finished.
Martin
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An update. After four attempts and a lot of learning, I got one that works. Nice sliding fit in the nut.
I even cut a key way! I used a hss parting tool lying sideways in the lantern post, locked the spindle with the back gear and took very light cuts moving the carriage back and forth. It worked better than expected.
I turned a part of the screw with a carbide insert, which left it looking scratched up, although its smooth to the touch. I still prefer hss though. Nothing better than the finish off a shear tool.
Pics to prove it happened.
Original and half finished copy.
Finished!
The key way. https://uploads.tapatalk-cdn.com/201...941ee9e9a1.jpghttps://uploads.tapatalk-cdn.com/201...4b2da33c5a.jpghttps://uploads.tapatalk-cdn.com/201...729579f87c.jpg
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Nice work:2tsup:. Better to have several tries and get it right, than one go and give up, and an awkward one tooo.
Kryn
The thread or the protruding part of the thread of the new on the left looks like it has a rounded end with a torn edge. Or is that just in need of being cleaned up? The one on the right looks cleanly square at the outside margin.
Just wondering if its a matter of camera angle or it really has a different quality.
Hi Guys,
Pictures convey an awful lot of information ! But can also be quite deceiving. Camera angles and lighting all enhance or disguise features.
I've taken pictures of work that I've done, that looks good until you photograph it, then suddenly all the imperfections stand out like a sore thumb.
Boris, you've called it out correctly. The finished screw has a rough thread. I'm still not sure why it cut like that. The clean thread was slightly oversize.
Seeing it on the bigger screen of my PC makes it even more obvious. It feels smooth in the nut, I assume that's because all the load is taken on the flanks which are smooth.
I'm going to do what I should have done earlier and call this the first complete test and get stuck into another hopefully final version.
Stay tuned...
Martin
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