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Thread: ACME 1/2 - 8 LH rod available ?
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27th Nov 2011, 11:20 PM #1
ACME 1/2 - 8 LH rod available ?
I see ROTON sell this size in stainless and in mild steel lengths ? . Is it available anywhere in Aust. ? Are ROTON OK to deal with ? Mike
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28th Nov 2011, 01:28 AM #2Dave J Guest
It would be available from Aus, but at a hugely inflated price like everything else.
I have heard good things about Roton from the US guys, but haven't heard anything about Aussies buying from them
This is a thread from not long ago here, it seems postage was expensive. If you do go that way maybe Dean would go in with you to get his piece.
http://www.woodworkforums.com/f65/ro...plying-142633/
Dave
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28th Nov 2011, 10:06 AM #3
Ok
Thanks Dave ... maybe I could try to make a length myself .... others have done it . The tricky bit is grinding the tool . Mike ..PS have you ever made a ACME thread yourself ? But , because I need around a 14" length , I think I would need a travelling steady for the Sheraton , which I havent got .
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28th Nov 2011, 03:30 PM #4
Hi Mike,
There were a few related threads to that, I think the best deal was from use-enco...
Try here..
Enco - Guaranteed Lowest Prices on Machinery, Tools and Shop Supplies
Regards
Ray
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28th Nov 2011, 05:42 PM #5Most Valued Member
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ACME is a PITA to cut and I do speak from experience. I once made a new leadscrew for a lathe back before I knew better.
I'd rather cut a square thread. Much easier and just as good for moving slideways etc. Hard to impossible to machine-cut using dies etc so that's where ACME is common.
I recently made some new screws for a P-B chuck, they were 1/2-8 LH IIRC. I cut about 250mm length without using a travelling steady without problems though using one would be better.
Making a square thread tap is a PITA, however, so nothing is perfect. I made a long one with a gentle taper and a pilot when I did it. Silver steel witt the teeth backed off using a file & Dremel grinder, heated with an oxy torch, quenched & tempered to dark straw then used carefully once. Probably still in a box I haven't unpacked yet...
PDW
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28th Nov 2011, 05:55 PM #6
PITA stuff
OK ... about it being difficult to cut . There is a very detailed thread ( no pun intended ) on that USA practical metalwork forum , about cutting a ACME thread . The guy wrote it up very well and explained it . He had a ACME thread gauge to set up the tool. Its worth trying , as the material is so cheap... how much is one metre of 12L 1/2" stock , peanuts . Might take 3 or 4 attempts to get it close , then
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28th Nov 2011, 07:42 PM #7Dave J Guest
Hi Mike,
I have never cut an acme thread my self because I have never had a machine that needed it. If I needed one I would do my best to make it, and think I could pull it off easy enough. It's the same with square thread that I am going to need one for my taper attachment. If we don't try we will never know, but I think you could do it.
Even if you just use a short piece of mild steel mounted in the chuck to practice on, so you don't need a steady for the time being, it will give you confidence in cutting it.
The tool grinding is not hard, but I do think you will need a follow rest, even if you just make up something out of scrap steel welded up to suit. Roller bearing fingers might work better similar to the ones Pipeclay makes.
I gave this link in the second thread below, so it should help you out in seeing the process, it's the same one PDW talked about above.
Making a new Cross Slide Acme Screw - Practical Machinist - Largest Manufacturing Technology Forum on the Web
http://www.woodworkforums.com/f65/cr...-issue-143259/
The diamond style car jacks have 1/2 left hand square thread from memory. I have heard of a few guys using these for cross slide and compound screws.
If you go ahead and make one keep us updated, as I am sure eveyone will help out if needed.
Dave
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28th Nov 2011, 07:49 PM #8Dave J Guest
I see you have already have seen that PM thread.
I forgot to say if you need a acme gauge, Len on ebay has stainless steel ones for $15 posted. They look to be OK but I don't know as I haven't bought on as I have a old Starrett one here. Most gauges have them on the end.
Dave
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28th Nov 2011, 08:18 PM #9Most Valued Member
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If I was going to do it again, I'd cut the thread root first, same as a square thread, then clean up the flanks. That would be a lot easier and I think you'd get a cleaner thread.
When I did mine I used 1085 hot rolled bar. That was not fun even on a big, rigid Yamazaki lathe with follow rest. Worked, though, well enough to restore a clapped out lathe to some years more use as the old screw had a round thread profile & split nuts to (very loosely) match.
PDW
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28th Nov 2011, 11:42 PM #104-6-4
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acme thread.
Greetings chaps the trick to cutting an acme thread is in grinding the tool. To get the most strength in the bit it is advisable to use a round piece of tool steel. A holder has to be made so you can rotate the bit so the clearance is the same on both sides of the bit. Anothe problem is that the bit has to be narrower that the finished thread so there is clearance so the bit will not dig in. I would have thjought that the nut would have been a bigger problem. I will look in my collection and see what I have. 4-6-4
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29th Nov 2011, 07:38 AM #11Most Valued Member
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29th Nov 2011, 06:49 PM #12Dave J Guest
I know it doesn't help you out (unless you wanted to make a new dial), but I thought I would let everyone know RDG have cheap acme taps in both LH and RH.
The sizes are 7/16 x 10, 3/8 x10, 1/2 x 10, 5/8 x 10 and 3/4 x 5. http://www.rdgtools.co.uk/acatalog/ACME_TAPS__LEFT_HAND_.html
RDG Tools - Online Engineering Tools ACME TAPS "RIGHT HAND"
They also have the dies in 7/16 x 10, 3/8 x10, 1/2 x 10.
RDG Tools - Online Engineering Tools Acme Split Dies
I put a guy in the US onto them and even though he only wanted one, he found to buy a second one was nearly free postage. It worked out $55 US for the 5/8 pair posted, and both him and the fellow that did the job for him, where both happy with the quality and the way the taps cut.
Dave
PS
You can add things to cart on the RDG website to see the postage price.
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29th Nov 2011, 07:41 PM #13
Tubalcain ACME
He has two informative U tube movies on the topic ... he uses acetal rod to demonstrate the process of cutting a ACME thread . MIKE
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29th Nov 2011, 08:17 PM #14Philomath in training
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4-6-4 is right - the hardest thing about cutting an ACME is grinding the tool right. After that it's not much more involved than cutting a normal thread. I find that if the thread needs replacing the chances are that the nut does too, so provided you have the right pitch you the form does not have to be 100% as you can make to suit each other.
One trick I'd like to try one day is cutting the thread a little longer and gashing the end so that it would act as a crude tap to do the final clean up of the nut, as it's usually the corners of the nut thread that cause me problems. With luck it should also give you a size for size thread nut combination.
I make machine nuts out of phosphor bronze, so something to bear in mind is really sharp tools are needed otherwise there is a lot of heat and not a lot of chips.
Michael
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29th Nov 2011, 09:21 PM #15Dave J Guest
Hi Michael,
I have read about many guys that have either cut the thread longer than needed or bought a longer thread rod to make a tap up for the nut. I also see it recommended on a lot of forums from guys with experience, so it would work fine.
Dave
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