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Thread: S20 buttress thread
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15th Apr 2017, 11:11 AM #16Most Valued Member
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yah thanks Greg. ill just have to have a crack. im sure it doesnmt need to be the closest fitting thread.
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15th Apr 2017, 11:15 AM #17Philomath in training
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I'm not familiar with the specific form, but a buttress thread is for heavy force in one direction and light in the other. The 5 degree side is the important one; when loaded I would expect the 45 degrees to be in clearance. On that basis, the 5 degree flank is the one I would be taking pains to get right and use as a basis for set up. The 45 degree side can vary a little without drastic consequences.
Michael
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20th Apr 2017, 12:55 PM #18Most Valued Member
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Yes I've cut the Schaublin threads, the major difficulty was in getting the pitch correct as it is 1.666 pitch. A bit of juggling with change gears on the lathe and it's no biggie. Like most threads, the angles aren't absolutely critical, and the engagement will just be poor if you don't get it quite right. However that won't cause the world to stop turning, you will just need to cut them loose and the end result won't be as strong. Obviously not ideal and if you can hit 45/5 accurately then that should be something to aim for. There are lots of ways to set it up, but if you're limited with resources I'd suggest making up angle templates of 45 and 5 degrees so your HSS blank can ride along them on your grinder tool rest. They don't need to be steel and you could mark it out on a piece of cardboard for all it matters. I find the less resources I have the more creative I need to get. It may be slower but it's the end result that matters. I can't recall how I did mine, sorry it was a long time ago now, probably on the surface grinder orientated the other way.
Based on my own experience with him I cannot more strongly NOT recommend the seller linked to for the dies. These dies are hard to get and he's one of the few who sells them. I ordered one to clean up the threads I'd cut (not required as it turned out, but I ordered it in anticipation of a Bozo attempt as at the time I hadn't done anything like this and wasn't sure how it would go). When it finally turned up it was absolute rubbish, completely unusable. I took photos of how bad it was and sent them to the seller. His reaction was the standard Chinese warranty customer service ... he tried to deny anything was wrong with it and it was my fault. I said the photos didn't lie and this was a joke. He finally agreed if I sent it back he would refund my money (it wasn't a cheap die BTW). My wife sent in back registered mail, obviously at my expense. What we didn't realise is that registered mail doesn't have tracking, the post office person screwed up and told my wife it did. The seller claimed he hadn't received it. After a bit of to and fro he again tied to blame me saying I had "damaged it". Given that it was unused that wasn't possible, so I asked him how would he know that if he hadn't received it! By that stage the ebay period for disputes had expired and required tracking, he reminded me of that and told me to bugger off. End result I was down the cost of the POS die, the postage to Australia and the return registered mail. It remains one of the only true really bad experiences on ebay where I did my money, about a hundred bucks all up IIRC. I've had other issues on ebay as I'm a big user, but never complain unless it's really warranted and the sellers have always agreed it was a valid complaint and we've settled to everyone's satisfaction. Anyway, that's my experience with that seller for what it's worth and I'll never touch them again with a 20 ft barge pole (other than to suggest where to shave the pole!).
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20th Apr 2017, 01:23 PM #19Golden Member
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I've always cut mine with a cheque to Franz Singer. Not cheap, but always results in a wonderful outcome.
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23rd Apr 2017, 01:31 PM #20Most Valued Member
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thanks pete. for your input on grinding a tool and not buying the die. i did look online for a die but couldn't find a s20. die.
and way i really should have a go at cutting this thread.
hi variant did you buy S20 draw bar adapter
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23rd Apr 2017, 05:10 PM #21Most Valued Member
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Oh yeah definitely have a go, grinding the tool is no big deal and of course cutting it is normal. You can even do threading with the compound offset if you want to. I haven't done any for a while so can't recall if I did that or just plunged them.
Just be aware there has been a bit of a crossover with two different threads in this forum's thread. The Schaublin/Aciera thread (W20 thread) is nominal 20 mm and 1.66667 pitch, that's what I've cut. I believe the Deckel (S20) is 2 mm pitch, so be careful of which one you want. Obviously the 2 mm is easier to cut as any metric lathe can do it straight from the gearbox. The 1.667 pitch needs some juggling of change gears to achieve the pitch.
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23rd Apr 2017, 06:07 PM #22
The one I got was a bit cheaper than the ebay link I posted, it was from aliexpress, so my expectations of quality are on the lower end of the scale, but visually it looks just fine.
Here is a link to the seller, but I notice the W20 die is no longer listed.
https://www.aliexpress.com/store/gro...608.0.0.rP7iJe
Here's a screen grab of the one I got. It might help track down a supplier for someone.
W20_Die.jpg
The Aliexpress seller has the brilliant ( confidence inspiring ) name of "Bob's Grocery Shop"
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23rd Apr 2017, 06:39 PM #23Most Valued Member
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Ha ha, well they can't blame Google translate as Google is blocked there by the great firewall of China A bit weird when there as, along with the expected, PM won't work, presumably because of the ads served.
It was Merlin Tools I dealt with, not good experience I'm afraid.
Again, just a heads-up that's a W20 die and not an S20 die.
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23rd Apr 2017, 08:15 PM #24Golden Member
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They are studs. S20 one end and M16 or 5/8 the other. This allows me to screw them into any BT or CAT 40 tooling and keep the great original S20x2 buttress drawbar.
Here are some: 5 Anzugsbolzen S20x2 NEU z.B. für Deckel Fräsmaschine. | eBay
As a side note, I highly rate Singer. He has always done the right thing by me with postage (sometimes free!) and has even at times shipped before I have paid. I guess he deals with people in good faith.
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23rd Apr 2017, 08:44 PM #25
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23rd Apr 2017, 10:24 PM #26Most Valued Member
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23rd Apr 2017, 10:26 PM #27Most Valued Member
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23rd Apr 2017, 11:11 PM #28Most Valued Member
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Yeah good luck with that. I have M16, 5/8-11 in Cat 40 (got the extension bit) BT40 (no extension) etc etc. I have a lot of short thread adaptors (M16 coupling nuts work well) and it's a right PITA. Sometimes I feel like shooting the machine tool people for not agreeing on a standard, any standard would have done.
Some of my stuff also has that 20mm buttress thread.
PDW
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24th Apr 2017, 10:40 AM #29Most Valued Member
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24th Apr 2017, 12:06 PM #30
I have a Schaffner cylindrical grinder that uses W20's There's a few pictures here //metalworkforums.com/f65/t1993...nt#post1907628
The plan is to grind an ER32 straight shank collet chuck between centers to the required taper, then anneal just the end so I can cut the W20 thread, if all goes according to plan and I get lucky the run-out should be ok.
Most of the time I'd expect to be grinding between centers, but in the rare cases that's not possible, I'd like the option to use ER32 collets. I don't want to shell out for a set of W20 collets that I'd hardly ever use.
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