MadModder
Gallery, Projects and General => How do I?? => Topic started by: Brass_Machine on November 05, 2010, 02:36:17 PM
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So as my thread title says, I have to do some 35mm x1.5 threading. Priced out the tap... cheapest i found so far is about $120USD! Not bad, but not good either. Now, I have never threaded on my lathe... So is it possible to cut a 35MM X 1.5 on an imperial 7x10 lathe? Should I just cough the money up for the tap?
Eric
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Should be doable but with some errors if you don't have a metric leadscrew.
http://littlemachineshop.com/Reference/change_gears.php?func=submit&soughtTPI=1.5&threadUnits=mm&leadScrewPitch=16&addGears=
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That's a good link. Didn't know they had that on their site. I just down loaded a small thread calculator from HERE (http://varmintal.com/alath.htm)
Getting somewhere now. Looks like I gotta bore out to 33.5MM...
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As said, it should be doable, obviously there will be a margin of error, but assuming that you are not threading to a very great depth the error should be negligable.
Marv Klotz has a calc program for change gears and it gives you the errors as well, might be worth a look.
Tim
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Getting somewhere now. Looks like I gotta bore out to 33.5MM...
That's right, Eric. For the usual metric thread forms, the tap drill (or bore) is easily calculated. Simply subtract the pitch from the major diameter. So 35 - 1.5 = 33.5mm.
Andy
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Fortunately the depth isn't that great. Maybe 15mm tops. Now to find or grind an internal thread tool!
Eric
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A small boring bar makes a good holder for a short threading tool bit.
Joe
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I do not think there has to be an error, I know it is possible to cut perfect inch threads with a metric lead screw provided you have the required compound 120/127 change wheel so I presume there is a way to go the other direction? :scratch:
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Eric,
Are you sure your little lathe is in fact completely imperial?
A lot of the far eastern machines are in fact metric, 'made' to cut and work in imperial.
Like John above, we both have metric lathes, but they can cut perfect imperial with just a gear change. On the smaller lathes, they usually use a 63 or 64 gear to make it cut 'almost' imperial. Have you such a gear size in your train? If so then it is in fact a metric machine, and with the correct gears in there, will turn perfect metric.
John
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Hi there,
The firm below are well worth remembering for future projects.
http://www.tapdie.com/html/metric_taps_or_taps_metric__ta.html
Bry
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I have been trying to pump that one into them for ages Bry, but they seem to prefer the cheaper versions.
Having just spent nearly 1000 squid updating all my tap and die sets and obtaining a few others, that shows how much I respect their quality.
Hopefully I will never need to buy another tap or die, except for specials.
Bogs
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1000quid. :jaw:
So what's your exact line of work Bogs are you a Rolls chappy?
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Hi there,
The firm below are well worth remembering for future projects.
http://www.tapdie.com/html/metric_taps_or_taps_metric__ta.html
Bry
I thought they were quite expensive when I was looking for an M39*4 tap... :(
Cheaper just to buy another backplate... :scratch:
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They look to have some quality kit but probably not the cheapest.
So whats the best tapping material these days is HSS preferred to High carbon taps? I guess coated taps might be a slight advantage also?
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Bry,
It just so happens, I did build the hand built R-R's in times gone past. The factory where it used to happen is only about 1.5 miles from where I live.
My machine shop was built to provide affordable high precision small order contracts. Unfortunately that was kicked in the head due to personal reasons.
But now I am on a slightly different slant, something I can easily cope with, designing and/or making one off's for people who don't have machining facilities, and aren't too worried over time scales and how much it will cost. Outlays for tooling are very quickly recouped, and I am not worried if nothing goes into my pocket. Doing it that way, my shop costs me nothing other than a bit of my time and effort.
When you do work for other people, you can only give them the best, and so the tooling for that sort of work is where the most money is spent. Rough a**ed work for myself and other people, plus if people want to borrow my tools, then the old sets of taps and dies get used.
I have found that the T&D company supply cutting tools in HQS. I don't know what that means, but once you use them to cut stainless, you don't worry about what they are made of, they just do the job with no problems at all, like a hot knife thru butter, unlike the HSS ones I used to use for such jobs, which really struggled at times. For 3mm and above, all thread cutting in my shop is done mainly by machine or power tools.
Like below, power tap the brass fingers with a 5mm LH coarse tap on the lathe, then single point the same thread onto the SS rods for a perfectly straight and perfect matching thread.
Don't ask what it is for.
Bogs
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Eric,
Sorry to hijack your thread.
If you have trouble making what you want, send me some sort of sketch and I will see what I can do for you.
John
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Eric,
Sorry to hijack your thread.
If you have trouble making what you want, send me some sort of sketch and I will see what I can do for you.
John
No worries :)
Checked my lathe, got the imperial lead screw. Don't think I have much to worry about except the technique. Been wanting to learn to thread on the lathe :)
Eric
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John, The Tap & Die people in the previous link are the folks you buy from? Just wondering. I need to buy a
few odd BA and BSF tap/dies to round out my tooling, and had looked at them, but didn't know if they were selling
good stuff or snake oil when the page mentions "Highest Quality Steel". That kind of "specification" often
puts me off as some sort of marketing ploy.
I have been looking for good HSS tooling, but mostly find the typical Chinese (junky) carbon steel stuff.
It's easy to get good tooling in the States in SAE/NF/NC etc., and I know what to look for in those, but no
idea what is good when a company says something like HQS for BA and BSF tools.
If they are your recommendation, I'll know where to go for Brit threading tools.
Thanks!
Dean
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Hi Guys,
Does anybody know where the Tap and Die company gets its taps and dies made? I know they make a big thing about the boxes being "British" made, but seem to make no mention of their other items.
Ned
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I suspect that they are made in either the UK or India, but they have a great reputation for quality from all over.
If I was doing a fairly long production job, I would always take advantage of their discount rates (works out cheaper than carbon taps). But now I find that I have dozens of brand new taps and dies in odd sizes, because I could never wear them out. I found that one would cut 100's of threads in all sorts of materials, mainly stainless and bronze, and still be good to go.
Dean,
I will go thru my 'extras', and send you a couple, they might not be sizes you would normally use, but hey, if they are freebies, it don't matter. Then you can get a 'feel' for the quality.
I still have your address so no worries on that score.
John
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Very interesting with regards R R.
That loonytune reeks quality.
Those HQS taps certainly sound good I use to so hate tapping knowing that the M6 or M8 could so easily snap.
Also have any of you chaps tried coated taps?
So do you offer lathe turning work Bogs?
Regs
Bry
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So can any of you lathe lads turn the part below:-
(http://img214.imageshack.us/img214/5456/tagwa.jpg)
(http://img210.imageshack.us/img210/1966/tag2y.jpg)
It's a fixed bezel for a Tag Heuer watch doesn't have to be mega tight tolerances but needs to look right a tolerance of 0.1mm should be plenty good enough the part can also be cemented in place. I usually refinish bezels but this ones way past refinishing unless you have a micro welder. :(
Material 316L SS
Rough sizes are O.D 38mm I.D. 32mm thickness around 3mm.
I'll speak to the client but I think the chap would be happy to pay £20-£40 for the part.
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I bought this threading tool from Mesa Tool. http://www.mesatool.com/index.php?main_page=product_info&cPath=4&products_id=14 (http://www.mesatool.com/index.php?main_page=product_info&cPath=4&products_id=14)
Beats tying to grind a HSS threading tool for small thread pitches.
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Dean,
I will go thru my 'extras', and send you a couple, they might not be sizes you would normally use, but hey, if they are freebies, it don't matter. Then you can get a 'feel' for the quality.
I still have your address so no worries on that score.
John
Well thank you, John! I had looked at a number of British suppliers trying to decide what products would be worth having shipped
over here. I get a customer now and then that needs something made with small BA or BSF threads. I'll go on your recommendation
and order a few things from Tap & Die next month. I'll have to make up another list! ; )
Dean
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I recently got a couple of 1/4" x 32 ME taps and a die which are marked "T & D". I haven't used them other than for a test piece in free cutting steel, because I was (am) concerned about the burrs on both taps and die. The test piece certainly seems to have a reasonable female thread, and a previously made male part seems to fit ok.
But I'm still worried about the burrs, which are still there after tapping the test piece. Most of the parts for which I got the taps and die are light alloy, I haven't yet made a test piece in Alum. Alloy, mainly due to lack of time.
Am I worried about nothing?? I do tend to be a bit pedantic sometimes
cheers
Bill Pudney
Adelaide
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Why not run the tap and die until all burrs are worn off?
Bry
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That's really why I did the test piece. It seemed to make little difference to the burrs. Why worry I hear you say?? As I mentioned I am a bit (!) pedantic and it seems to me that the form of the thread could well be altered. The fact that the male part appears to fit without a huge amount of rattling about only confuses me more!! The thread feels gritty when being assembled, despite everything being very clean (ultrasonically) and lightly oiled.
Maybe this needs to be on a separate thread, sorry to hijack etc etc.
cheers
Bill Pudney
Adelaide, Australia
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Probably best to email the tap and die technical department and see what they say.
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By the sounds of it you have got hold of some carbon tools from Tom & Dick's Cheapo Emporium, and I am sure they wouldn't have come from Tap & Die, as mentioned above.
The rough edges and burrs are a sort of giveaway sign of carbon screw cutting tooling. Very soft steel would be the hardest thing I would attempt to use them on. They normally cut OK, but tend to be very brittle in use and can easily snap, not just the taps, but dies as well.
A thing that I always found with cheap carbon sets I have used in the past, is the even with the die fully expanded (centre screw, tightened) the generated thread would still screw into the threaded hole, whereas normally, with good quality T & D's the male thread would be much too large to fit into the threaded hole, and so then you creep down in size until you get a perfect fit.
You would also most probably find that carbon taps are not serial, but all the same diameter in a set of 3. Good quality HSS have a smaller OD for first and second cut and a final larger OD for the plug (bottoming) tap. This allows for easier tapping to full size in tough or hard materials.
A lot of people don't realise that you can get serial taps, so when they only use say a second cut to thread a hole, the screws are either tight going in or sometimes lock up solid as they are screwed in because the threaded hole is in fact too small.
Arc Euro do some good general purpose serial taps at very reasonable prices for a set, and I have some in my collection, but never having used them on a real tough stuff, I can't comment on their life expectancy.
http://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Taps
Bogs
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Just to reply to Bry's request.
Normally I will help anybody out, but after being stuck on a commission project for almost a year, and that should be finished within a week or so, I am taking no more work on for the time being, and getting some of my own backlog cleared.
I have so many half finished projects on the go, this has become a necessary step for me.
BUT, if you have the material (plus a bit extra in case of problems) and the original article that can be measured up accurately, and there are no strict time deadlines, I could slip it in between doing a few of my own jobs when time becomes available, most probably it would be completed within two or three weeks.
That is about the best I can do for you.
Bogs
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I regularly use my (genuinely) imperial lathe for metric threads without problems.