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 ARCHIVED TOPIC: Home made hoop bender


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wilberweb - Posted - 04/12/2010:  23:17:40


Sorry if this has been Posted.
I looked in the Archive's I found manufactured metal benders and brass hoop jointing and brazing information but nothing on building a hoop bender.
Has any one built there own brass hoop tone ring bender? I was going to attempt to build my own hoop and tone ring bender. My Idea was to take two aluminum disks cut to the correct diameter with a rabbit joint on the outside edge of each die as to form a groove in the middle of the two aluminum die's or blank,as to form a groove in the center, the groove will except a tone ring aluminum or brass flat bar, then I would have a clamp at one end to hold the material in place it would be similar to the benders you see at harbor freight, or grizzly. I would have a handle with two roller bearings at the base, the roller bearings will ride on the outside of the brass tone ring or hoop. at that point all I need to do is start moving the handle around the form and that should bend the brass around the aluminum die. I think that will work. Does any one else have any Ideas on how to build a brass tone ring and hoop bender?

thanks
Larry

rudy - Posted - 04/13/2010:  04:49:08


Hi Larry,
Something like this?
This worked for me, but it requires a bit of trial and error to get the precise diameter to result. One problem may be the expense and time it takes to do this without knowing what your results might be.

roy.carpenter - Posted - 04/13/2010:  05:02:03


I made the same kind as rudy and worked out OK for me too. Roy

ronwalker49 - Posted - 04/13/2010:  05:02:42


Hey Rudy that's a great Idea....Harbor Freight was good enough to take my broken ring roller back (and issued me a gift card)...I haven't decided what to but with that yet....Please explain the trial & error part....

timmo_1949 - Posted - 04/13/2010:  08:59:00


Very clever work there but you'll need to make a new circle for each size of ring. I have used for some time now the Harbor Freight "planetary ring roller"
harborfreight.com/cpi/ctaf/dis...ber=36790, now sold as the "gear driven ring roller". I guess threads on it didn't show up in a seach for "hoop bender". They will handle reasonable heavy stock. I recently used mine to bend a 1" X 3/16" brass bracket band.

rudy - Posted - 04/13/2010:  09:23:12


ron,
The trial and error part is accounting for springback of the metal after it is bent. The circular form shown is somewhat smaller than the intended diameter of the finished ring and the point that contacts the bar stock has to be determined somewhat by trial and error to obtain the desired result.

timmo,
The original poster stated that he had found "manufactured metal benders" in the archive search but wanted to know about build-your-own benders. I have the Harbor Freight bender and use it to bend tension bands and tone rings from brass and aluminum bar stock. It's not perfect, but gets the job done. The home built bender I pictured produced a much truer bend, but I was using aluminum. I'm not sure what the results would be if I tried to bend 3/16" by 1/2" brass the same way.
It is part of an extensive build your own banjo web page(s) that I put up several years ago and the original photo and text describing the making and use of the bender can be found here:

angelfire.com/music2/construct/page1A.html


Edited by - rudy on 04/13/2010 09:36:08

wilberweb - Posted - 04/13/2010:  10:13:04


Great reply's
I didn't know about the ring roller at harbor freight timmo, just the benders, I did see your web site Rudy, I downloaded the pdf plans as well, its the same concept as Rudy's bender but with steel handle and aluminum circles or dies with a groove in the center to produce the tone ring as well,just like Rudy's bender it has a roller bearing assembly at the base of the steel handle with a slot cut in it to adjust the bearing assembly for different diameter rings, also has different dies for different size banjo's. I could get the parts from the local goodwill, or or hardware store.

wilberweb - Posted - 04/13/2010:  10:49:08


I see where Rudy's has a screw for holding the aluminum ring down, my bender would have a small block of steel with two screws on each end, then the aluminum would have threads in the die to hold the brass in place, something like a vice, it would hold the brass a few inches away from the handle so the other end would meet up with the brass on the completion of the bend. I would have a steel die with the same kind of clamp to hold the rings closed for brazing its a lot of work making this set up but it will be better in the long run on making hoops faster.

Hazen - Posted - 04/13/2010:  15:02:38


You can remove the need to account for springback in a bender like the one that Rudy built if you design it in a way as to allow you to silver solder the joint in the jig. I use a similar set up to bend 3/16" by 3/4". If you can find anything round that is a little larger then you can have it turned down to the exact size for a modest price. A piece of pipe works well. Next you can fasten it to a plate to provide a place to mount the bending arm. Remember to grind a relief where you want to solder so that you do not join your hoop to the jig. A side grinder does a great job. Now it is all a matter of having enough clamps and clamping every couple of inches as you bend, and then learning to silver solder. You can TIG the bands together, but solder works well.

I hope that this was helpful.

wilberweb - Posted - 04/13/2010:  20:24:15


So Hazen are you talking about cutting the steel pipe on the end, and use the same diameter pipe as the banjo ring to make a die? I was thinking solid aluminum plates, then take a circle cutter attached to my band saw with a metal blade
then make the circle use a 3/4" aluminum. I can cut a rabbit with my router table in aluminum its soft enough to cut with a wood bit, or flute cutters work good, I would need to turn the speed of my router down so it would act like a milling machine, should work.

Hazen - Posted - 04/13/2010:  22:53:08


A circle jig like you are talking about would do well. Just drill a hole in the plate a little off the edge every 3 or 4 inches so that you can clamp the hoop to the jig or the hoop wants to spring back after your bending arm passes a point. The Clamps allow you to use a jig of the exact size of the rim you are building for. The other thing to make sure that you have is the relief cut where the two ends come together. If you do it like this you can permanently fasten the hoop while it is on the jig and you do not have to worry about deformation when you take it off. If the finished hoop goes a little oblong when you take it off you can roll it on the floor or a table to take it back to a circle again. If you want to talk about this further contact me off forum and I can go more in depth with you. I am wiling to share the mistakes that I have made if you want to hear about them.

Hazen

wilberweb - Posted - 04/14/2010:  10:12:36


I see, I was going to clamp it on the jig like you suggested, and braze it in place thanks for offering to share your mistakes with me, but that's the fun part of learning is making mistakes the sweet part is you know not to make that mistake again and it kind of gives you a reason to look back on what projects you built as well, me I like the mistakes if you know what I mean sounds weird.

Jonnycake White - Posted - 04/14/2010:  13:04:01


quote:
Originally posted by rudy

The home built bender I pictured produced a much truer bend, but I was using aluminum. I'm not sure what the results would be if I tried to bend 3/16" by 1/2" brass the same way.




I bent 1/4 x 1" brass for a tension/tone ring on a banjo I have not yet completed. It was a real pain to bend. I had to keep annealing it to get it to bend and not spring back. That's a little thicker than 3/16 but I'd hesitate to try it again without a powerful ring roller.

ronwalker49 - Posted - 04/14/2010:  14:21:20


Jonnycake...I busted a bran new ring roller from harbor freight the first time I used it...Trying to roll a 1/4" X 1" brass ring....The maximum size on the roller was 1" X 3/16" but I had already bought the brass....I tried to go slow and be gentle but the "stand" that held the rollers was made of some kind of man made material (plastic) and it wouldn't take it....

wilberweb - Posted - 04/14/2010:  15:06:21


I thought brass was soft enough to bend easily, I wonder if you could heat it to make it easier to bend or would that temper it and make it more likely to sh-adder.

rudy - Posted - 04/14/2010:  19:15:24


Jon, Ron, and Wil,
I'd hate to think of hand-bending brass bar stock over 3/16" by 1/2". My Harbor Freight "roll forming machine" is heavy and made of solid bolted and welded steel. It's pretty beefy, but won't take anything over 3/16" by design.

Brass is a "work hardening material", which means that it becomes much more resistant to being shaped once the molecular structure is modified in the bending or working process. It takes a LOT of heat to get this size of bar stock to cherry red for the annealing process. I did not find a need for it, though.

Regarding bending and joining ends of a ring that naturally wants to spring back, I would not personally bend and hold the ring and then braze the ends to hold it. My experiance with metal (and wood) has taught me to work for no built in tension or stress when permanantly joining materials. Relying on the bonding agent (brazing brass or gluing wood) to hold materials that really would rather not be in that shape is asking for trouble eventually.
This would mean bending purposefully smaller diameter or whatever it takes to get the ring to stay in the correct position without force being applied.

If we weren't so stubborn, we would just have Bill Rickard send us a ring!

wilberweb - Posted - 04/15/2010:  09:27:43


I agree bill has some nice rings, but he also has the machinery to make those nice rings I emailed him on plans for those machines, but no E-mail back so I guess he doesn't want copy's of his machines maybe propitiatory.



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