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Tool for forming brass hinge rods

Posted: Tue Nov 26, 2013 7:45 pm
by Julian B
I will soon need to create some brass hinge rods for the various hinges on my Haflinger - from footwell covers to tool box lids. I have already bought some suitable brass rods which I can cut to length, but need to obtain a tool to help form the "dome" on each end. But I am not sure what they are called, and am struggling to find what I need on Google. Presumably it will be in the form of a concave tipped "punch", possibly of varying diameters to suit the various thickness of hinge rods that I have.

Does anyone know what these things are called?

TIA

Re: Tool for forming brass hinge rods

Posted: Tue Nov 26, 2013 8:19 pm
by heinkeljb
Julian,

I found this which will help explain what you are trying to do and the tools you need to achieve it. Look towards the bottom of the page for the info:-

http://modelsteam.myfreeforum.org/archi ... 40085.html

I know the tools you mean as "rivet snaps" but that's not to say they aren't called some thing else to others.

John

Re: Tool for forming brass hinge rods

Posted: Tue Nov 26, 2013 9:39 pm
by Julian B
John - brilliant, just what I wanted.

Do you know if a rivet snap of a particular size is the "rod size" or the size of the dome diameter? And it still surprises me how much of this engineering stuff is still sized in fractions of an inch and not mm!

Re: Tool for forming brass hinge rods

Posted: Tue Nov 26, 2013 10:26 pm
by heinkeljb
Usually based on the "stem" of the rivet, so in your case the diameter of the rod you are trying to turn into a rivet!

The reason a lot of this stuff is in imperial sizes is because the major users of these technologies are the ship building and steam engine industries and they are still using / mending stuff more than 50 years old!

John

Re: Tool for forming brass hinge rods

Posted: Fri Nov 29, 2013 5:22 pm
by Markus
Julian,

Upload a photo of how it went when you have time and the tool. I still have mine to do and would appreciate some advice on forming the head.

M

Re: Tool for forming brass hinge rods

Posted: Sat Dec 07, 2013 11:37 am
by Julian B
I am still really struggling to get these brass rod hinge pins formed nicely. The brass is very brittle, and doesn't like being heated either ...

I have tried using a concave punch to form a mushroom head, but it never looks very nice.
I have tried using a hammer to merely squash one end, but that too looks poor.
I have tried using a sharp ended punch to "splay" the end, but bits just chip off.

And this is doing the first end. By the time a (not very nice) one ended pin is inserted into the hinge it is virtually impossible to then form the other end.

There must be an easier solution, but I can't think what that is. What have others done?

Re: Tool for forming brass hinge rods

Posted: Sat Dec 07, 2013 12:48 pm
by Julian B
Another thought - might I better to go for copper rod if I can get it? It'll be much softer to form, but perhaps too soft to be any good as a hinge pin? That said, very few of the hinges are put to much use on an intermittently used Haflinger!

Re: Tool for forming brass hinge rods

Posted: Sat Dec 07, 2013 2:50 pm
by heinkeljb
The other option you have would require the use of a lathe. You could go for a thicker piece of rod which was the diameter of the formed end that you want. Machine the dome on one end, then turn down the rest of the shaft to what ever length is required. Then you only have one end to have to form. Obviously, forming brass appears to require slow pressure rather than a sudden strike.

Just had a thought;

Depending on the length of the rod you require for the hinge pin, maybe you could get a steel rod down which you can drill a hole the diameter of you brass rod. Put the brass rod down the hole so it is supported on all sides by the wall of the steel rod and at the bottom. Cut the brass rod so that there is just enough brass above the steel rod. Now put the steel rod in a vice so it is supported so that you can put one of your concave punches on it and hit it ONCE nice and hard. A lot of the time, the formed end of such a rivet is not nice is because the punch "jumps" or you have to hit it more than once. That causes marks on the domed surface. Maybe a fine file will allow you to "reface" that domed surface to make if look nice.
Still doesn't really get round doing the other end though!

That end could be done if you could make a tool that would allow you to increase the pressure on a die with the correct shape in it: something like a "G" cramp with a pair of "dies" at each end of your brass rod.

These techniques certainly work on short "rivets", but longer "hinge pins" might bend in the middle unless supported so that he only place deformation can occur is at the ends.

John

Re: Tool for forming brass hinge rods

Posted: Sat Dec 07, 2013 3:01 pm
by Julian B
Thanks John,

That all sounds a bit complicated - I have found some copper rods of varying diameter so might try that route.

I did try to squash the second end of a brass rod in situ with a G clamp, but the access space is so limited that the G clamp pressure was off centre, and so it just spun away.

Re: Tool for forming brass hinge rods

Posted: Sat Dec 07, 2013 3:13 pm
by heinkeljb
I don't think a "" cramp is the correct tool to use, but the shape of it is what is needed. I think a "bespoke" tool would have to be made - something which won't bend, but has a screw thread that can provide the required pressure directly down the centre of your rod.

So a nice thick piece of steel with a "U" shape cut in it the correct length for your hinge you are forming. Then drill and tap a hole near the end of one of the "legs" - like the "G" cramp into which you can screw a bolt. Two "dies" with concave forms of the shape you want at either end of your rod. Wind up the bolt and that should do the job..... Fingers crossed!

John

Re: Tool for forming brass hinge rods

Posted: Sun Dec 08, 2013 2:03 am
by ogdenenterprise
I had some stainless steel hinges made to the same sizes as original when I replaced my foot well covers ,I supplied the hollow & solid rods, they welded the flat plates to the rods , they made a good job of the hinges but they charged me $200AU for the work. I nearly fell off my perch when they told me how much but then I thought we usually pay 2 or 3 times as much for things here in Cairns. Hey ho.
Dave

Re: Tool for forming brass hinge rods

Posted: Fri Dec 20, 2013 8:45 am
by Julian B
Bearing in mind the little use the hinges get on a Haflinger - except for the engine bay top cover !!!! - would copper rods be worth trying? Or would they be much too soft? They would be much more malleable & easy to install.

I know that copper will wear much more quickly than brass, but knowing how infrequently a Haflinger tends to get used it might be a compromise worth taking?

Re: Tool for forming brass hinge rods

Posted: Fri Dec 20, 2013 6:42 pm
by heinkeljb
I don't see a problem with using copper if you have suitable bits to use. As you say, they will wear a little quicker but then you can always replace them with another bit or maybe by that time figured out how to do the brass ones properly!

Maybe some brass tubing of the right diameter with brass screws with rounded tops screwed into the ends of the tubing?

John

Re: Tool for forming brass hinge rods

Posted: Sat Jul 01, 2017 4:21 pm
by Czechsix
Just going through old posts, and I read the issue about getting the proper dome on the rod.

From experience, if you're using brass rod and the alloy is fracturing - you need to anneal it. Easiest way to do it, at least for me, is to heat it red, and plunge it into water. Exact opposite of ferrous annealing.

To form the dome, you'll have to experiment a bit, but it can be done easily with a vise to hold the work, a couple of steel plates as vice jaws that are properly sized for the rod, and a small hammer. You don't really need to get a doming or rivet form. Especially if you're only doing a few.

Secret to this is take your time, and work the metal. Light taps are about right, with a small hammer. Get it mostly right, you'll anneal at least once, and finally to save time just grab the sand paper or a file and remove the planishing marks.

If there's any interest I can do a short video.

Re: Tool for forming brass hinge rods

Posted: Tue Jul 04, 2017 11:20 pm
by walderse
Try sections of either metric or Imperial/SAE "all thread" cut to length and cap each end with an aircraft Nyloc nut. An appropriate length Allen Head machine screw is even better.

I have disassembled some Haflingers that someone had used nails as hinge pins. they still had the pointed tip on the nail. The nail was secured simply by bending the exposed end so the nail could not back out.

Another option is to use a long split cotter pin bending the free ends as one normally would.

Obviously, none of the above will ever pass Concours D'Elegance scrutiny but will get the vehicle functional to an acceptable level with a minimum of effort.

Hope this helps.
Take care.

Jim Molloy
Waldersee Farm
http://www.northwestmogfest.com