making bunches of bolts

Hey all,
I'm a wooden boatbuilder and we usually make our own silicon bronze bolts. The are usually 1/4, 5/16, 3/8, 7/16, 1/2, sometimes bigger but not often. I've been cutting the threads on our lathe with the bolt in the chuck and using a die, a hand on the top handle, the bottom handle riding between the ways. It's great when the die is new, but after a hundred or so (or if someone uses the die to cut steel !!!) it gets tough (and hot).
To clarify what we make: like these http://www.ccfasteners.com/images/FFNB.jpg
They are fin-neck bolts (like a carriage bolt, but with a flush head and fins instead of a square to keep from turning), usually 3 to 5 inches long, sometimes a foot or longer. We have purchased many from suppliers in the past but usually have to order longer than needed and then cut the threads longer, it seems more cost effective to us to make the bolts we need. There can be just a couple need per boat (on small repair jobs) or a few hundred for a whole boat.
What's the best (cost effective) bet for cutting threads on these? I've heard of thread forming dies but don't know much about them - could they be an option? Any help will be appreciated!
Eide

Eide wrote:
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Do you know what sizes they need to be in advance, or are you always making them different each time?
My only experience with this is from 30 years ago, where it proved quite economical to order 10000 at a time, custom made on a screw machine. I imagine that having these made 100 at a time on an NC lathe may be an option -- if nothing else you could have them made long with really deep threads, ready for you to cut off to length.
And keep in mind that if this is something that's ideal for you it's probably something you can sell to others in your industry. On the one hand you'll be helping your competitors -- on the other hand you'll be making $$ every time they make a sale.

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Each boat is different, even the same class of boat can be different. It's hard to tell what will be needed in advance.
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I would think you should investigate a die head, which is a far superior method for generating threads. Better yet would be thread rolling---which yields a much stronger thread than one that is machined, although that may not be an issue in your application. Personally, I avoid using hand dies like the plague, although with a properly configured holder they aren't horrible. Running them with a hand stock is often a recipe for failure.
Because you're making various threads, it's entirely possible you're already using the best procedure, at least from an economical standpoint. It would likely not be cost effective to roll threads in small numbers. A die head, on the other hand, could be cheaper in the long haul------just expensive at first.
Harold

Harold and Susan Vordos wrote:
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Is silicon bronze malleable enough to roll threads without breaking the bolt or the roller?

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Silicon bronze bolts with rolled threads are readily available. They are superior to machined threads in tensile strength.
Harold

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It's not clear to me that one can roll threads in silicon bronze.
I would probably go with a die head.
Jim

Thanks all for your comments! I just have a few more ?s...
Could you give me a quick primer on die heads? Doing a search just gives me a thousand options - of which I know nothing about. Is there a brand to look for? A brand to stay away from? If you were to buy a die head, how much would you spend on one?
Thanks again Eide
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    The die head maker which I am most familiar with is Geometric. In the UK, there is a different brand. There is also a German made clone of the Geometric which I have found to be very good.
    It holds a set of four "chasers" which cut the threads, and (when used in a turret) can be set up to open automatically when the thread reaches the desired length.
    The chasers can be changed to cut other threads.
    The chasers can be sharpened, with a proper fixture and a surface grinder.
    The chasers can be bought from the maker with a custom grind specific to the material which you intend to thread.
    As for prices -- I think that you are talking over $1000.00 new, but I got mine from eBay auctions over time.
    With a carefully set up lathe, you could use them from a toolpost with the right holder. (I would suggest a 1" boring bar holder for the largest of the ones which I use, and adaptor sleeves for the smaller ones.)
    It takes a bit of careful work to get them set at the right height, and the cross-feed at the right position.
    Once that is done, you simply crank the carriage to bring the die head into contact with the rotating workpiece, and have the bed stop set to stop the carriage at the right point to release the chasers, after which you simply crank the carriage back (with the spindle and workpiece still rotating, if you need do do other work -- no need to reverse the spindle to back it off of the workpiece -- the chasers will have retracted far enough to clear the workpiece.
    I've never used one from the carriage, but I do a lot of work from time to time from the bed turret on my 12x24" Clausing lathe.
    I hope that this is some help.
    Good Luck,         DoN.

On Sun, 05 Mar 2006 05:19:34 +0000, snipped-for-privacy@d-and-d.com (DoN. Nichols) wrote:
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Depending on the volume..having the blanks thread rolled may be cheaper than buying a Geometric head and chasers. Its not particularly expensive to have them rolled..and its a superior thread
Gunner
"A prudent man foresees the difficulties ahead and prepares for them; the simpleton goes blindly on and suffers the consequences." - Proverbs 22:3

As Gunner and Harold both mentioned, rolled threads are superior to cut threads. Bicycle spokes have very small diameters, and to keep from "losing metal" at the threaded ends they were very commonly produced by thread rolling. A good friend of mine owns a bicycle store in town, and he makes spokes for people with unusual wheel diameters with a small, hand-operated rolling machine.
One very easy way to find manufacturers and distributors of equipment and services is The Thomas Register. They were around in paper form (huge set of books) for many decades; I don't really know when they started but they long predate my career. The good news is they went on the internet a few years ago and are free to search at: http://www.thomasnet.com
Doing a search for "thread rolling machine" produced about twenty categories, some of the more likely ones are: Machinery: Thread Rolling (126 companies) Machine Tool Systems For Thread Rolling (6 companies) Dies: Thread Rolling (155 companies) Screws: Thread Rolling (138 companies) Thread Rolling Equipment (21 companies) Heads: Thread Rolling (7 companies) Many of these companies will be listed in more than one category, but it looks like there's quite a few of them out there.
When you start looking at a category, you can see on the left-hand side a list where you can refine your results either geographically by state, or (more importantly) by company type. I almost always start searching with the company type set to "Manufacturer", because they usually have more complete product literature and the application folks can answer real questions. If the manufacturer has a website, and most do now, the site will be listed on the information page.
OK, just for fun, a few unusual searches typed in at random: "Gold Rivets" 30 companies, 24 of them manufacturers "Brewery Vats" 7 companies, all manufacturers "Concrete Pumps" 125 companies, 63 manufacturers
Sorry for the long post. I've used Thomas Register for over 25 years and always found them to be complete and quite accurate. I'd really be kind of lost without it. I just thought I'd mention their existance.
Dave

If you need rolled threads or centerless grinding contact the makers of model airplane engines. I don't have precise url's but Fox in Fort Smith Arkansa or RJL in California have all the tools to do this stuff. Do a quick web search. I'm sure they could help you.. I have no affiliation with either of them

On 5 Mar 2006 01:45:49 -0800, "LowEnergyParticle"
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I recently brokered two thread rolling machines for a grand each. So they are readily available, if someone really needs to do a lot of threading. Gunner
"A prudent man foresees the difficulties ahead and prepares for them; the simpleton goes blindly on and suffers the consequences." - Proverbs 22:3

Thanks for the description of The Thomas Register, I've seen there website many times, but it's usually too much information all at once. I'll try them again.
Eide
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As Gunner and Harold both mentioned, rolled threads are superior to cut threads. Bicycle spokes have very small diameters, and to keep from "losing metal" at the threaded ends they were very commonly produced by thread rolling. A good friend of mine owns a bicycle store in town, and he makes spokes for people with unusual wheel diameters with a small, hand-operated rolling machine.
One very easy way to find manufacturers and distributors of equipment and services is The Thomas Register. They were around in paper form (huge set of books) for many decades; I don't really know when they started but they long predate my career. The good news is they went on the internet a few years ago and are free to search at: http://www.thomasnet.com
Doing a search for "thread rolling machine" produced about twenty categories, some of the more likely ones are: Machinery: Thread Rolling (126 companies) Machine Tool Systems For Thread Rolling (6 companies) Dies: Thread Rolling (155 companies) Screws: Thread Rolling (138 companies) Thread Rolling Equipment (21 companies) Heads: Thread Rolling (7 companies) Many of these companies will be listed in more than one category, but it looks like there's quite a few of them out there.
When you start looking at a category, you can see on the left-hand side a list where you can refine your results either geographically by state, or (more importantly) by company type. I almost always start searching with the company type set to "Manufacturer", because they usually have more complete product literature and the application folks can answer real questions. If the manufacturer has a website, and most do now, the site will be listed on the information page.
OK, just for fun, a few unusual searches typed in at random: "Gold Rivets" 30 companies, 24 of them manufacturers "Brewery Vats" 7 companies, all manufacturers "Concrete Pumps" 125 companies, 63 manufacturers
Sorry for the long post. I've used Thomas Register for over 25 years and always found them to be complete and quite accurate. I'd really be kind of lost without it. I just thought I'd mention their existance.
Dave

Thanks, great info! I think I've got enough info to get myself into trouble!! I'll check out Geometric and see what they have to offer...
Eide
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A 9/16 D Geometric, or equivalent, would be a good size for you from your described use. They are readily available, even on the used market (think ebay), and chasers can be purchased to meet your requirements, as DoN noted. If you feel you'd need to cut threads larger than 9/16", you might be better off exploring a larger head. They get more and more expensive as they get larger, and chasers are more expensive as well, so don't buy one larger than your needs.
Harold

9/16 sounds like a good size to me too. Thanks for all your input!
Eide
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Welcome!
Good luck with your search. You'll really enjoy using a die head. If you have a bed turret at your disposal, you can generate threads, start to finish, in about 10 seconds. One of the nice features is the die opening at the end, eliminating the need to remove the die by reversing.
Harold

snipped-for-privacy@TAKEOUToldbranch.com says...
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I've got an extra 9/16D that needs a little TLC I'm not real attached to if you decide to got this route. But before you do, I'd suggest you also check ebay for the availability of chasers. I sold a 3/4D a few years ago and at the time the smaller heads and chasers were fetching a premium.
The other thing to consider is a pipe threader with a set of bolt dies. If you need to do larger sizes, a 2" pipe threader will have the capacity of very large lathe. I've threaded many sili-bronze keel bolts up to 1-1/4" both with a pipe threader and with a large turret lathe and geometric head. The pipe threader works just as well and is portable to boot.
Ned Simmons