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08-21-2019, 01:46 AM | #1 |
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Which tap and die set
Hi Guys,
A question from the metric side of the ocean. A model A is build up with Lots of bolts and nuts. Even metric so i’ve noticed. I’m planning to buy a tap and die set, but I’m not sure which to buy. What do I need for my model A? UNC/UNF or BSW/BSF? Anyone? Thanks! |
08-21-2019, 06:05 AM | #2 |
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Re: Which tap and die set
I was going to say that I think it is safe to say that there aren’t any BSW/F threads on a Model A, but who knows about the UK models with their smaller motors, etc.?
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08-21-2019, 06:24 AM | #3 |
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Re: Which tap and die set
Buy a decent thread pitch gauge set. looks like a bunch of different pitch and height saw teeth and some decent digital calipers. This will help immensely. Trust nothing, verify everything because not only did they use oddball stuff prewar but you have 90 years of fingers in there too.
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08-21-2019, 06:55 AM | #4 |
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Re: Which tap and die set
As a starting point, I'd suggest a set of UNC and UNF taps and dies. (Unified National Coarse and Unified National Fine). That should do you except for those strange "gauge threads" no one else understands - well, I don't. Maybe I am about to learn something too.
It should be noted that BSW and UNC are the same up to 1/2" so far as the TPI goes but the thread form is 55 degrees vs 60 degrees. At 1/2, BSW is 12 TPI and UNC, 13 TPI. Weird, the way they changed so little for UNC!
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08-21-2019, 07:56 AM | #5 |
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Re: Which tap and die set
Here in USA the model A's has many fine threads. Way more than one might have expected.
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08-21-2019, 08:23 AM | #6 |
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Re: Which tap and die set
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08-21-2019, 08:54 AM | #7 |
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Re: Which tap and die set
Ford used rather tight clearance tolerances on many fasteners. If you buy the average tap/die set it will be fit class 2A/2B and you will ruin parts if you use the taps/dies to clean up nicked threads. You need a set with 3A(external) & 3B(internal) clearance tolerances.
My go-to for taps/dies with the clearance specs I want is MSC Industrial Supply Direct Co. Inc. (US) https://www.mscdirect.com/ |
08-21-2019, 09:28 AM | #8 |
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Re: Which tap and die set
While Whitworth generally follows the UNC/UNF thread TPI convention, the taps/dies themselves have a 55 degree included angle.
In my basement I have a circa 1860 Wood turning lathe made by one the early Worcester, MA machine tool builders (Likely Lathe & Morse or their predecessors.) The headstock bearing caps are threaded 7/16 -14 BSW - It was common for pre-Civil War American machine tool builders to "import" their tooling for threading. A 7/16-14 UNC bolt will not screw into the hole more than about 8 turns. I was tempted to drive a 7/16-14 tap into the hole to allow use of UNC dies to make the machine cut bolt - but I resisted opting instead for a $24.95 BSW die from Ebay. Originality matter in historic machines. At least in my mind/wallet. Joe K
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08-21-2019, 09:31 AM | #9 | |
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Re: Which tap and die set
Mike,
As we know the differential bolts and case are a tighter thread than common taps and dies. Are those 3A and 3B or are they a different, even tighter tolerance? Transmission cases also? Thanks Quote:
Last edited by Benson; 08-21-2019 at 09:51 AM. |
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08-21-2019, 01:30 PM | #10 | |
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Re: Which tap and die set
Quote:
That said, I have run class 3 cutters over differential, trans, and engine threads and fasteners without removing anything more than the deformed metal. A class 2 cutter would leave the walls of the thread cut or scraped down to new metal- bad, bad, bad. In any case that type of clean up is a last resort after steel bore brushes and 60 degree die sinkers files fail to give the desired outcome. Another option is thread forming rather than cutting taps, also available in various tolerance specs. I used those a lot on AlMag castings when I had a foundry back in the 70's & 80's. As far as dies go, the adjustable versions permit dialing in the clearance you want. Not something for the casual user. |
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08-21-2019, 06:16 PM | #11 |
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Re: Which tap and die set
All the old USA built Ford stuff with some minor exceptions is Unified type for the most part. I don't know about the UK built cars. It depends on how much was shipped from the USA. The Dagenham Ford plant was still under construction in the first few years of the Model A production.
I've always kept British Association and British Standard tooling around due to work on Rolls Royce aero engines and all the old British cars and motorcycles I've owned over the years. Thread pitch gauges are invaluable to identifying fasteners. The stuff is all still available from UK sources. My BS and BA wrenches & socket sets are all Snap On since there were so many Rolls Royce aero engines back in the day. The old Merlin engines and Dart turboprops were all popular back when. |
08-22-2019, 02:52 AM | #12 |
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Re: Which tap and die set
When cleaning old threads DO NOT be tempted to use taps and dies. There are thread restoring tools out there that are designed to do the job. A classic example of the "wrong way" are back axle banjo bolts which have been "restored" with a die. Then there's the torment of stopping lubricant leaks past the threads.
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08-22-2019, 03:32 AM | #13 |
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Re: Which tap and die set
Thanks!
Wow, I thought I had a simple question. But learned much My Roadster is an American made by the way. But I didn't know that the british made cars, could be different. Which is to be expected of course. |
08-22-2019, 08:08 AM | #14 |
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Re: Which tap and die set
Mike,
Thank you very much. for the help. We use MSC-direct at the shop Last edited by Benson; 08-22-2019 at 10:14 AM. |
08-22-2019, 09:18 AM | #15 | |
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Re: Which tap and die set
Quote:
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08-22-2019, 06:25 PM | #16 | |
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Re: Which tap and die set
Quote:
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06-03-2023, 07:10 PM | #17 |
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Re: Which tap and die set
I am in the process of setting the carrier bearing preload, as I rebolted the axle on the banjo, I stripped one of the blind holes at the pinion. Will helicoil or a larger bolt work? All 19 other holes are ok.
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06-03-2023, 08:46 PM | #18 |
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Re: Which tap and die set
Heli-Coils are common repairs. If properly installed, they are every bit as strong as the original thread and definitely more reliable.
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06-03-2023, 09:06 PM | #19 | |
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Re: Which tap and die set
Quote:
To chase those use an old head stud and cut some grooves in it so it looks like a tap. Then hold it with vise grips and use a lot of oil. That will clean out the rust and crud without cutting anything from the existing threads. For external threads a good wire wheel will get those looking new - any dings can be cleaned up with a small file rather than cutting all new threads. It's all about getting the existing threads clean to fasten and torque your parts not trying to make "new" threads. |
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06-04-2023, 10:05 AM | #20 |
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Re: Which tap and die set
What parts on the Model A have a Metric thread as the original poster claimed?
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