Author Topic: Ideas on trunion cap fixture (Read 1560 times)

Cat Whisperer · « **on:** December 26, 2004, 02:28:53 PM »

I've got some iron working tools, but I'm looking for a method of bending the two 90* bends and the 180* radius of a trunion cap.

I figure I'd then build a jig to drill the holes, but the question is, to get a good smooth radius with two sharp bends in just the right place does one do the radius first and then the 90's?

What would the bending fixture look like?

I hate to re-invent the 'wheel' knowing that SOMEONE has done this before.

Articifer Tom · « **Reply #1 on:** December 26, 2004, 05:31:04 PM »

Ok! Ill try . First if it's for a cannon it is not 180 * it's about 175 * on the top . the gun rest in the larger bottom piece and can be shot with out the cap ,note angle of cheeks on drawings and increased height of metal strap . Now best way I found is find a piece of heavy tubing that is big enough to go over your trunnion weld the formed bottom metal to it so that it matches the contour of the cheeks imbedded over HALF then cut the top 175 * Off set back on or temp. bolt and weld two short pieces on to make top strap along with round stock to dress end like drawings . The perfect trunnion strap! If I confused please ask ???s.

Calamity Jane · « **Reply #2 on:** December 27, 2004, 02:49:26 AM »

Yup, make it in three pieces.

On my 6-pounder, I bent one piece 180 degrees with the right I.D. Then I welded on the front and rear parts of the strap and cut off the excess of the 180. With gas welding, it looks like they were made from a single piece.

Cat Whisperer · « **Reply #3 on:** December 27, 2004, 03:08:20 AM »

Good explanations and advice, THANKS.

But, being hard headed and production minded, I'm going to try to build a fixture to take 1/8x1" strap iron and bend to shape. I can bend either bend (the 180* radius and the 90* sharp corner) very well; the question is how to build the fixture to do both well on the same piece of iron.

If I REALLY can't do that, I'll weld 3 pieces together.

Articifer Tom · « **Reply #4 on:** December 27, 2004, 11:50:05 AM »

Try finding copy of original drawing of the bending gig . It's in back of carriage drawing Artillery of the Land Services

Articifer Tom · « **Reply #5 on:** December 27, 2004, 11:57:24 AM »

Another way to do it if your going full scale is a wood pattern with all the nice tappers and rolls and have them cast of iron [alittle hardened ] . This is how did my 12 pdr. been using 15 years .Bedded with fibre glass to make strong and look perfect .

Cat Whisperer · « **Reply #6 on:** December 27, 2004, 12:09:42 PM »

Cool handle, Tom. Interesting to crank that into a search engine - took me twenty minutes to get back here.

I'm considering sevaral options now, for 1-1/2" diameter trunions using 1"x1/8" strap iron.

Cat Whisperer · « **Reply #7 on:** December 30, 2004, 01:37:51 AM »

Here's a prototype. They WILL get better.
This one's made by hammer bending the two 90* bends in a vice first, then bending the 180* radius.

I think I can eliminate the slight twist by jig bending both 90's.

1.5" prototype 01 trunion cap

Blaster · « **Reply #8 on:** December 30, 2004, 04:16:15 AM »

Tim, nice looking trunion cap. To assist someone like me, who doesn't know anything about fabrication of such an article, it'd be really quite helpful to place a penny, nickle, dime, quarter or some recognizable coin next to it to show the scale/size. I know that dimensions had already been mentioned but a picture is worth 10,000 words. This is only a suggestion from someone who doesn't know ANYTHING about building but is still very interested. :roll:

Cat Whisperer · « **Reply #9 on:** December 30, 2004, 05:56:49 AM »

Quote from: blaster

Tim, nice looking trunion cap. To assist someone like me, who doesn't know anything about fabrication of such an article, it'd be really quite helpful to place a penny, nickle, dime, quarter or some recognizable coin next to it to show the scale/size. I know that dimensions had already been mentioned but a picture is worth 10,000 words. This is only a suggestion from someone who doesn't know ANYTHING about building but is still very interested. :roll:

Good comments. It's made of 1/8" thick x 1" wide iron, started out about 6" long. It will fit a 1-1/2" diameter trunion. It's not good enough yet - need to iron out the little irregularities.

Double D · « **Reply #10 on:** December 30, 2004, 06:45:59 AM »

Tim,

You need one of those Iron workers like those guys who make wrought Iron fences use.

Douglas

Articifer Tom · « **Reply #11 on:** December 30, 2004, 11:03:47 AM »

Thanks, Cat Been using the handle for years and building since '89.Tried doing search on google [Netscape ] coundn't even find my self are you sure I exist! javascript:emoticon(':eek:')
Surprised

Part looks good Imay have confused you the info before was to build the whole strap and cap for cannon ,which is not 180* .
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Cat Whisperer · « **Reply #12 on:** December 30, 2004, 11:29:25 AM »

OK, thanks one an all for the comments.

I've made 2 trunion caps (but for 2" diameter trunions) and got them matched and reasonably well proportioned.

The KEY was not to bend the 90* bends to 90* but to only go to 75* and then to do the 180* radius.

On a later date I'll wrap up the 1-1/2 inch trunion caps, for now I'm happy with the 2" pair - which will go on my 4.5" mortar. Unless I come up with some 1-1/2" x 1/8" strap iron as the 1" looks a little narrow.

Procedure was as follows. A bending tool or set of jigs can be made much more simply than the tool I used, I used it because it was a $50 bargain a few years back.

CAV Trooper · « **Reply #13 on:** December 31, 2004, 04:41:48 PM »

Damn, I'm jealous. I sure wish I had a bunch of neat metal working equiptment. Sure would make life (read cannon and mortar making) much easier.

BTW, Lowes and Home Depot both sell 1/8" x 1 1/2" strap iron in 3' and 8' lengths.

Double D · « **Reply #14 on:** December 31, 2004, 05:44:26 PM »

oh, you do have an Iron worker....

Cat Whisperer · « **Reply #15 on:** January 01, 2005, 03:54:05 AM »

DD -

Yea. I forget the real name for it.

The problem with it is the same as with my lathes and mill (got all of them from a H.S. going out of the business of teaching metal working) is two fold: one: the equipment is there, but well worn and much abused (requiring fixing or making parts before using); and two: (as in this case) I have to teach myself what works and doesn't work and what sequences to do things in.

There is a tool (brand name) of Iron Worker - which uses hydraulics to cut and bend iron - great leverage and force. It has a vertical frame with all the power stuff at the top. It can cut or notch a 2" angle iron in a heartbeat! I want one!

Cav T -

I agree with you. I spent $1800 for a milling machine and two lathes just to support my habbit. Couldn't afford it, but couldn't afford not to. Original intent was (and is) to make a few bullet moulds the way I want them. Mortars and cannon have gotten into the que early.

Since it is so easy to do a basic trunion cap let me know if I can help. 1-1/2 and 2" are easy; any other size & I'll have to build tooling.

Cat Whisperer · « **Reply #16 on:** January 01, 2005, 03:57:36 AM »

Quote from: CAV Trooper

BTW, Lowes and Home Depot both sell 1/8" x 1 1/2" strap iron in 3' and 8' lengths.

Good resource. (Here in town there's a machine shop that sells me metal at their cost. The transactions are in cash and no receipts - draw your own conclusions.)

Lee1966 · « **Reply #17 on:** January 05, 2005, 11:36:18 AM »

Just goes to show, you need the right tool to do the right job.

Very good looking caps Tim.

Can you make me 2 for a 1 5/8 diameter trunnion out of 1 1/2" wide strap 1/8" thick?

Cat Whisperer · « **Reply #18 on:** January 05, 2005, 12:45:01 PM »

Quote from: Lee1966

.... Can you make me 2 for a 1 5/8 diameter trunnion out of 1 1/2" wide strap 1/8" thick?

Do-able. I need to get the 1-1/2 x 1/8 strap iron and a short length of round stock to make the tool around which to bend it. Simply a matter of a little time. I assume the center line of the trunion will be level with the surface of the trunion cap. From there I'll leave and inch or so extended on each side and let you position and drill the holes.

Lee1966 · « **Reply #19 on:** January 05, 2005, 01:15:09 PM »

Tim I solved my problem. :grin:

I had to set my trunnions just over 1/8th of an inch lower then center line in order to use the caps that came with my CCC naval carriage kit. :oops:

But in many ways thank you for letting me know you could have done that for me. THANK YOU :grin:

Cat Whisperer · « **Reply #20 on:** January 05, 2005, 02:37:22 PM »

Lee'66 -

The offer is the least I can do for the wealth of information and the fun I've derived from the participants of this forum. So the offer is still open - trunions are simple to make if one has the right tooling. Since I've got the tooling I'm willing to share the wealth.

This thread started out of my frustration in making them.

Through the course of experimentation and discussions the process that worked came to light. This is typical in engineering any process - having the sounding board available accelerates the process.

CAV Trooper · « **Reply #21 on:** January 05, 2005, 06:48:51 PM »

Quote

I had to set my trunnions just over 1/8th of an inch lower then center line in order to use the caps that came with my CCC naval carriage kit.

I had to do the exact same thing with the cast bronze caps I got from SBR for my King Howitzer. The trunnions are 2 1/8" and I found that for everything to fit, I needed 1" above the carriage cheeks and 1 1/8" below.

Is this sort of thing standard with cannons?

BADGER BOB · « **Reply #22 on:** January 06, 2005, 03:16:03 AM »

Howdy ya'll.There is a "store-bought" solution to the caps.At a plumbing supplier they should have riser clamps, a pair of straps about 1 1/8" wide by 1/8" thick with the trunnion bend already done. If you have 2" trunnions get a 2"clamp.They are designed to hold vertical piping in place in a multiple story building. They come in many sizes and are dirt cheap!
Hope this helps.Badger Bob