Author Topic: 7" Treble-Banded Brooke Rifle (Double Dovetail Insert Making and Fitting) (Read 6470 times)

Cat Whisperer · « **Reply #30 on:** December 01, 2007, 03:55:29 PM »

Awesome!

Simply awesome!

lance · « **Reply #31 on:** December 01, 2007, 04:29:12 PM »

I love the new pics of very impressive craftsmanship!!! i can't help but think about the original Tredegar Iron Workers. i'm trying to imagine how they did it, what they went through, all at a much bigger scale too! If there is some kind of award for master cannon builders, they should get one, and you guys too!!!!

seacoastartillery · « **Reply #32 on:** December 02, 2007, 01:59:10 PM »

Thank you gentlemen; we appreciate your compliments. You know Lance, we have thought about the artisans and craftsmen working in the gun foundries in the North and the South and it appears they put a lot more effort into the finishing than we first thought. After all the dirty, hot and downright dangerous work of pouring a tube and pulling it from the flask, who would want to sign up for finely finishing all of the critical areas around elevation mounts, sight masses, rimbases and trunnions in the Southern foundries OR the entire tube in the Northern foundries? Wherever we go evidence of finishing techniques usually reserved for statuary is there in plain sight for anyone to see.

Two examples out of many that we know of are the Brooke rifle along the southern promenade of White Point Gardens in Charleston, SC. It has all the important areas smooth and without any casting roughness at all. Another is the 100 Pdr. Parrott rifle in Denver's City Park. The entire tube including the reinforce is as smooth as a baby's bottom. These men exhibited a level of craftsmanship that certainly rivaled the fine furniture makers of that day. As for our efforts at Seacoast Artillery Co., we are merely following in their footsteps, trying to continue their tradition of excellence in cannon making.

Regards,

Tracy and Mike

Terry C. · « **Reply #33 on:** December 02, 2007, 03:09:37 PM »

Great photos. I can't wait to see the completed cannon!

Quote from: lance on December 01, 2007, 04:29:12 PM

i can't help but think about the original Tredegar Iron Workers. i'm trying to imagine how they did it, what they went through, all at a much bigger scale too!

This level of craftsmanship has led to more than one argument regarding the Tredegar 24-pounder iron siege gun, Model of 1845 (cast in 1851), located at the Confederate Veterans Memorial downtown.

Some people assume it's a fake because it's simply too smooth, and the detail is too sharp. Apparently, 150+ year old iron guns are supposed to be crudely made and roughly finished.

This a beautifully made gun, I'm proud to have it in our town. I can't imagine the amount of physical labor involved in this level of finish, given the technology of the time.

GGaskill · « **Reply #34 on:** December 02, 2007, 06:55:00 PM »

While these old iron guns may have been beautified at manufacture or at a later date, the real credit for their current pristine condition has to go the the handful of post-manufacture curators, etc., who have seen fit to keep a good coat of paint on those guns exposed to the weather. We've all seen examples that didn't get that kind of TLC and they show it.

Victor3 · « **Reply #35 on:** December 02, 2007, 07:19:30 PM »

Dang... What a job.

As I looked over the pics I was trying to envision all of the separate calculations, tools, setups and operations required for you to get this far (As a machinist type of guy, I know the pics only show a fraction of it all). I hope you guys charge more than a couple hundred bucks for that gun.

One thing I'm wondering - It seems that the connection points between the breech strap and the trunnion yoke forks will be under tremendous stress at firing. Being that the strap is mild steel, isn't there a chance that the area where the strap is pinned/keyed to the forks will be deformed?

Maybe I missed it, but is there anything other than the breech strap restraining rearward thrust of the barrel?

Edit - I forgot that it's a very heavy bbl and that the whole upper carriage moves rearward. Those factors will reduce stress at the connection.

lance · « **Reply #36 on:** December 03, 2007, 02:35:30 PM »

Terry C. that is a nice one! wish it was in my town........ like i said, the original Tredegar workers, and Mike and Tracy, should have awards for master cannon builders. Beautiful work!!!

seacoastartillery · « **Reply #37 on:** December 03, 2007, 05:17:53 PM »

Thanks guys for your continued confidence in us. I think we figured out all the math today and also a list of steps for the strap slotting operation and the tricky dovetail slot op. The sequence of steps here is the key, since we want all these pieces to be in a state of tension when we are through, ( no loose parts in this assembly), the exact sequence becomes very important, especially when you factor in heating and cooling the strap ends with the resulting expansion and contraction. No, we will not be machining the dovetails while heating the straps with a torch!!

Victor3, don't worry; we charge a bit more than $200. No, there is nothing besides the breech strap restraining the rearward thrust of the tube. The strap keeps the tube locked into the trunnion band and the trunnions keep the the tube and this 4 piece assembly on the upper carriage. The reason we used 1018 steel for the strap is that it is certainly stronger than wrought iron, while being closer to the original material than, say 8620 steel which is popular for high strength rifle actions. Remember that the upper carriage is only going to weigh about 15 pounds, and even factoring in inertia-at-rest and the amount of friction retarding the movement of tube and carriage on the iron-shod oak beams, as recoil occurs, we can't quite imagine that these 1" straps are going to stretch or bend in any amount that can be measured. All the wedges and dovetailed keys are as close to 1/6th scale as we can make them; we are looking forward to 100% function, just like the original.

Lance, we have visited the Tredegar Foundry and we studied those items on display as well as measuring the Brooke rifle in the parking lot, IN THE RAIN!! Cats and Dogs rain. Boy are we dedicated, or CRAZY! We know about master cannon founders; they certainly had them at the Tredegar. We are not in that class and never will be. The guys in Cold Spring, NY didn't do too badly either.

Terry and George, I mistakenly thought that we were the only ones who really took a close look at these silent sentinels in our country's parks and cemeteries. You fellows really brought up some good points about this interesting topic which is directly tied to the finish applied to our Brooke that we have already described.

Regards,

Mike and Tracy

seacoastartillery · « **Reply #38 on:** December 06, 2007, 06:49:16 PM »

Fixing vehicles all week, no time for cannon building. We should be back on it starting tomorrow; hope to post results of final fitting in approx. one week.

Regards,

Mike and Tracy

Cat Whisperer · « **Reply #39 on:** December 09, 2007, 02:43:20 PM »

Quote from: seacoastartillery on December 06, 2007, 06:49:16 PM

Fixing vehicles all week, no time for cannon building. We should be back on it starting tomorrow; hope to post results of final fitting in approx. one week.
Regards, Mike and Tracy

Understand that. Did 3 oil changes before dark yesterday. Beat the cold weather.

seacoastartillery · « **Reply #40 on:** December 16, 2007, 10:23:54 AM »

Tim, we finished the truck repairs just before the snow storm hit. Lucked out!!
The photos below give you a rough idea of all the work that had to be finished BEFORE we could proceed on machining and hand fitting the parts which make up the Trunnion-Band Assembly which includes the Trunnion-Band, the Yokes (2), the Wedges (2), the Dovetail Keys (4), and the Breech Strap. The reason that the order in which operations were accomplished was so important, is because once certain things are done, you can't go back and do other things because destructive dissassembly would have to precede your current op. An example is the reason for polishing the tube in the trunnion and breech areas. You can't go back and do this after the Dovetail Keys (4) are fitted and installed. You would be forced to drill and tap all four keys and remove them whith a slide-hammer to take the Trunnion-Band Assembly apart, which would destroy those, labor-intensive Dovetail Keys.

The basic plan is this: 1. Do all machining and polishing in areas not accessible after installation of Trunnion-Band Assembly.
2. Do all polishing of the Assembly's parts.
3. Mill slots in the Yokes and then file 75 deg. dovetails (female).
4. Machine slots and file 75 deg. dovetails (female) in the Breech Strap.
5. Make and heat-treat the 2.5 deg. Wedges.
6. Dry fit all parts to check proper fit of each. Calculate the length of each end of the Wedge so that it can be driven downward .25", after heating, e and have equal amounts protruding from the top and bottom of the Yoke.
7. Apply torch to expand the length of the Breech Strap ends.
8. When gap between ends and trunnion surface gets down to .010" from .020", drive Wedges to take out all looseness.
9. After the Straps have cooled, vigorously shake the trunnions to see if the entire assembly is in a state of Tension.
10. Check to see if the dovetails in the Yokes and the Breech Straps now line up. Re-do processes 6 through 9 if they DO NOT LINE UP.

Regards,

Tracy and Mike

This Trunnion-Band Assembly line drawing shows the relative size and position of all assembly parts. The Red-dashed line represents the 2.5 deg. front edge of the Wedge slot in the Breech Strap which the force applying edge of the Wedge pushes against as it is driven downward. The Blue-dashed line represents the back edge of the Wedge slots in the Yoke which stop rearward movement of the driven Wedge.

Here all parts are dry fitted with no looseness to transfer dovetail position from the Yoke to the Breech Strap. Lines are scribed into the marker blackened area on the Breech Strap ends.

Each trunnion's length must be milled to proper 1/6 scale length now.

Since the in-process centers were milled off during the trunnion shortening operation, correct, 1/6 scale size centers had to be lathe-drilled at this time.

This machinist's clamp was installed during the dry fitting process and a drill point is used to mark the Yoke's front relief edge on the Strap from which calculations bring a 2.5 deg. slant drilling start point to light on the top edge of the Breech Strap end.

Next an endmill removes waste from the Wedge slot, taking care not to actually touch the forward or rearward edges of the slot. These areas are finished with needle files.

The 2.5 deg., 0-1 tool steel, Wedge is hardened in a propane torch flame by heating it to a bright cherry red color, (in subdued light), and then quenching it in vegetable oil which works great and does not stink like burned motor oil does.

The hardened Wedge can be checked for hardness with an old file. Give the end of the Wedge a lick; the file should skate right off without cutting any filings. Now the Wedge is ready for tempering or "drawing back" to reduce it's hardness a bit to about 51-54 Rc and to make it much tougher so it can resist cracking when driven by hammer blows. We use a small electric furnace, (Ebay purchased), with 2,200 F. capability. 675 deg, F. for 1 hour, with open door cooling, works well to achieve a tough, non-deforming Wedge.

This photo shows the milling of the center of the Breech Strap dovetail slots with a .010" offset towards the breech end of the Strap. Hopefully the dovetail slots in the Yokes and the Strap ends will line up after heat expansion, Wedge driving, and then cooling so custom made double-dovetail keys can be inserted to keep the Yoke extensions in place during recoil.

Our 75 deg. dovetail milling cutter still did not arrive, so more hand filed dovetails are in order. First, you make a special dovetail file with one "safe" edge by taking a regular triangular file and grinding off the teeth on one side so that it and one other side form a 75 deg. angle. In use, put the safe side down in your square milled notch and square up the file with the front and the top edge of the Strap. File slowly with straight ahead arm movements. Do 5 or 6 practice pieces before you do one that MUST be correct like these 4 must be.

Do you see how square the file is to the side of the Breech Strap? It must be kept in this attitude all the way through the stroke or your dovetail surfaces will have taper.

In-process inspection with an eye loupe is essential so minor variations can be corrected before they get too big and ruin the job.

The next few photos, shown in about a week, will describe the making and the fitting of those male dovetail inserts. More, high stress, hand filing! Gotta love it!!

lance · « **Reply #41 on:** December 16, 2007, 01:45:55 PM »

Mike and Tracy, i'm trying to understand how all this works.......the wedge, is it's main purpose to hold the strap until the dovetail keys are installed? do the keys and wedge work in unison to hold it all together? is there more tension on the wedge or keys? only asking cause i'm trying to learn..........

seacoastartillery · « **Reply #42 on:** December 16, 2007, 02:27:24 PM »

Lance, those are darn good questions. Yes, the Wedges hold the strap in tension, after Strap ends are torch heated, and the Wedges are hammered downward. The keys also keep the Yoke ends from separating during the stress this assy. is subjected to during the RECOIL IMPULSE upon firing. We believe these parts work in unison, but we can't prove that as yet. We believe the Wedges do most of the heavy duty holding. That's why they are only 2.5 deg. and not 7 or 8 deg. Wedges under 7 deg, tend to hold under shock or vibration, those over, do not. It's a compromise between excessive Wedge movement and holding power.
More tension on the Wedges, we believe.

Very intelligent questions, Lance; thanks for helping a lot of people understand the workings of this unique assembly better. We are definitely included in that group, by the way.

Ask away!!

Mike and Tracy

seacoastartillery · « **Reply #43 on:** December 27, 2007, 05:10:37 PM »

Lots of family activities have delayed this post and final fitting of the double dovetail which secures the Yokes and the Breech Strap ends. The post will try to explain the heat expansion of the Breech Straps and driving the two Yoke and Strap securing Wedges. First we will post the last target from the Second Prototype test barrel. This was finally proof that our year long quest for an accurate Brooke-style, slant-hook rifled tube was on the right track. Yet another test barrel was done, with yet another, slightly faster twist; with this barrel our accuracy goals were achieved. With the permission of our customer, we will post this final test barrel target and the first production tube target after the first 7" Treble-Banded Brooke Rifle No. 001 and these targets are delivered to the customer sometime this summer.

We will be happy to answer any questions about the purpose of any part or any of the mfg. methods depicted in the photos below.

Regards,

Mike and Tracy

This target was shot on the high plains north of Denver, CO in early June of 2007.

You can see that all parts in the assembly are polished and the preheat gap of .020" exists. All parts are tightly drawn up before heating.

First one side, then the other, was heated with a propane torch to expand the Breech Strap ends as evenly as possible. The Wedges were tapped lightly to take up slack as it was created. You may have to go back to the line drawing of this assembly to see what each part does.

The Wedges have been driven about .230" downward which locks the Straps into a state of tension when they cool. The gap between the Strap ends and the Trunnion surface has been reduced by .010" and after cooling is only .010" wide. The .010" offset between the Yoke dovetails and the Strap dovetails is GONE. THEY NOW LINE UP!!

The gap after cooling. The trunnions were grabbed and shaken vigorously; there was no looseness of any part in the assembly.

With the No-Twist clamps in position, we are ready for double-dovetail insert fitting. These must be hand filed because they must fit the hand filed female dovetails exactly and tightly. The clamps keep the Yoke ends from spreading as the dovetail inserts are tapped into place. Their purpose in the assy. is to prevent the Yokes from spreading during recoil.

That's about it until Saturday night. Any questions?

Ex 49'er · « **Reply #44 on:** December 27, 2007, 08:53:57 PM »

Wow ! ! ! You guys sure have a lot of patience to do such precise work. I can't cut a straight piece of wood with an electric saw. My hat's off to you.

Victor3 · « **Reply #45 on:** December 28, 2007, 07:44:14 PM »

I have to admit, I'm envious. You guys are doing something unique that will never be duplicated. I hope that all of your guns are well cared for and passed down for generations to come.

Do you engrave your barrels with your own personal mark/cartouche that identifies you as the builders?

seacoastartillery · « **Reply #46 on:** December 28, 2007, 11:53:16 PM »

You're right, Ex 49'er, we do have lots of patience and persistence; without these qualities we would be nowhere. It is really difficult to try to explain how anyone can stay focused on one narrow goal, such as our accuracy goal, when there are so many other important items vying for attention. We decided a long time ago that we are NOT multitasking types. We are Bulldog types who grab one problem at a time, solve it, and then go on to the next highest priority.

To answer your question, Victor3, we do not engrave or stamp our barrels with any marks that I.D. Seacoast Artillery Company. Only the authentic, historical markings that were stamped on the original, full size 100 Pdr. Parrott Rifle, Model 1861 are stamped on our exact, 1/6 scale, recreations. If you go to our Banner ad at the top of this forum and pull up our web site and go to the Product Information menu, you can click on Parrott Gallery and look at the second photo which is the sterling silver, "Maker's Plate" that we affix to each cannon which we sell. The company name, type of cannon, serial no. and other pertinent data is displayed there. This plate is always found on the base or platform upon which sits the carriage.
We also hope that the seacoast guns we make are cared for. Probably most will be, as they are located in collections or on a special shelf or display area in a gun-room. Let's be honest here; most will never be fired, so a lot of wear and tear will not happen to them.

Regards,

Tracy and Mike

seacoastartillery · « **Reply #47 on:** December 29, 2007, 06:38:23 PM »

This making of and fitting of the double dovetail inserts is the final task relating to the Trunnion-Band Assembly. This set of photos is the last that will be shown of the 7" Treble-Banded Brooke Rifle manufacturing operations until after this seacoast gun is delivered to the customer sometime this summer. As always, we are happy to answer any questions you may have about any feature on this gun.

Regards,

Mike and Tracy

Our 75 deg. dovetail milling tool arrived in time to make the inserts. A small bar of 4142 steel, 30 Rc, is squared up then milled to the basic dovetail shape slowly and cautiously. The height of the dbl. dovetail recess minus .010" is the height of the insert. You have to remember that only the diagonal surfaces of the insert pull the Yoke ends and the Breech strap ends together.

Side view of dovetail insert milling. The bar is cut long enough for two inserts of .333" length and an inch of unmilled bar to facilitate handling.

The dbl. dovetail shape takes form. All diagonal surfaces are approx. 008" oversize. Lots of careful filing lays ahead. FILE TO FIT is a term Mike and I heard a lot at gunsmithing school.

After 15 minutes of gentle filing, the insert begins to fit.

After blackening the diagonal surfaces the insert is lightly tapped into the recess until will not go any more. It is then removed and studied.

The bright spots are the high points which must be filed away.

When about half of the insert will fit the recess, it is cut off and trimmed to the correct length and placed into a machinist's clamp to be held more accurately for final filing.

Using a rectangular, needle file, the insert looses only the material under it's bright spots. You MUST keep the file parallel with the filed surface to avoid a taper. I had one gunsmihing school instructor who rarely said anything but, "Remove what you don't need and ONLY what you don't need!" He was correct, of course; that is exactly what to do.

The insert is tapped further into the recess, but seems to be a little tight on top after looking at the marker blacked surfaces.

Mike and I can remove .002" or .003" from the top surface very quickly and precisely with a fine mill bastard file, but Watch Out this is a quick way to ruin the whole thing if you don't know how to file accurately. The edge of the vise is a good guide for maintaining parallelism of the file and the workpiece surface.

A close up of the right side half done.

Except for a little polishing, the job is done.

Any questions on fitting metal parts or anything about this powerful Confederate rifle will be answered right away. So ask, and you will receive.

Mike and Tracy

Div Arty · « **Reply #48 on:** December 30, 2007, 07:31:11 AM »

DD & CW

Is it possible to preserve the information and photos Seacoast Artillery has offered us? Maybe in a sticky of their own. Something for the future where we can reference it without losing the area it is stored. Just a thought, hate to have this education gone to waste. I think anyone that presents a good idea or instruction of a type of construction should be posted there.

Thanks and to all a Happy and Healthy New Year. Ron

Cat Whisperer · « **Reply #49 on:** December 30, 2007, 07:40:52 AM »

Ron -

In a word - YES. There are several options.

Thanks, Stay tuned.

Double D · « **Reply #50 on:** December 30, 2007, 08:42:59 AM »

Yes, we can.

The Best way is to link them into the Cannon plans sticky. The problem with making them their own sticky is that we end up with a whole page stickies and all the new posts are over on page two and three.

Tim obviously has something in mind--whatcha thinking about Tim?

lance · « **Reply #51 on:** December 30, 2007, 09:16:56 AM »

if you can preserve the pics and info of this history in the making, in months ahead after the gun is compleated. will there be some woodworking pics to add? i've only had a small viewing of Mike and Tracy's excellent wood work on their Parrot base. This Brooke should have lot's of excellent wood work to see.

seacoastartillery · « **Reply #52 on:** December 30, 2007, 10:08:41 AM »

Div Arty, very nice of you to make these suggestions; we would prefer a solution that makes submitals from ANY business OR private individual of a "Method of Work" text/photo series possible. That's our thinking on this topic.

Lance, you are correct, there will be a few woodworking pics available after we deliver this beast to our midwest friend and customer this summer. We can't reveal our method now, but since you are an accomplished woodworker, yourself, "How would you keep a 3" X 2.5" X 32" unpainted piece of white oak straight under all conditions of humidity??" Did you notice how I slipped that word, unpainted, in there? This is a test, of course, to see if the moderator stationed in S.A. reads this stuff. Before we head to Montana I guess we will have to slap on a quick coat of raw Linseed oil with a little Japan drier in it.

Best regards,

Mike and Tracy

lance · « **Reply #53 on:** December 30, 2007, 10:28:08 AM »

not done, but here is how i'm keeping 2 1/8" x 7" x 31" oak sides straight under all conditions of humidity. Oh, it won't get paint either, just linseed oil.

Cat Whisperer · « **Reply #54 on:** December 30, 2007, 10:38:46 AM »

Hmmmm. MATCH GRADE woodwork.

This competition thing has got a grip on ya!

seacoastartillery · « **Reply #55 on:** December 30, 2007, 11:59:07 AM »

Tim, you're right, that sure looks like MATCH GRADE to us. Lance, you have a mighty fine way with wood! Whatever that is, it has a real SOLID and precisely made, look to it which is the look we are going for on our Brooke seacoast rifle chassis. The original had to support 25,000 lbs. of tube and upper carriage, so the beams were quite massive and even at 1/6 scale, they will look about like your substantial assembly here. Thanks very much for sharing that picture. I bet that those beams stay straight!!

Regards,

Tracy and Mike

Terry C. · « **Reply #56 on:** December 30, 2007, 12:54:23 PM »

Lance, am I correct that the base in your photo is for the Dom Carpenter full-scale 12-pounder Tredegar mortar?

Tracy or Mike, are those photos stored on the GBO hosting site?

I'm still finding old posts of mine with dead photo links, due to the fact that I've had three different hosting sites fold on me (two of them were pay sites) over the years.

Image hosts come and go. This thread needs to be preserved, with the photos intact.

lance · « **Reply #57 on:** December 30, 2007, 02:25:09 PM »

Thank you, Tim, Mike and Tracy, and Terry C........ Yes the base is for the Dom made full scale 12pd'er Tredegar Mortar. like i said not done, but it's getting there. still have to make top and bottom trunnion plates, the ones on the bottom will be inletted so it sits flat. All hardware will be painted flat black to match the tube, since i'm a poor Confederate and can't find any paint, i'm having to use boiled linseed oil for the base. Yes, those beams will stay straight!........really it's nothing to compare against wood for a Brooke, but it's all i had on hand.

Double D · « **Reply #58 on:** December 30, 2007, 04:32:38 PM »

Keeping boards straight was a concern with the originals also. There is a good discussion on this from the original records included in the AOP plans for the Napolean Gun. They talk about making the trail and which direction the heart would should face and such things. They go on for each major piece giving grain orientation or alignment.

seacoastartillery · « **Reply #59 on:** December 31, 2007, 04:44:52 PM »

Terry C., yes those photos are stored on myhostedpics, but we wised up after our recent, "Exceeding Bandwidth" message and we took the action of organizing all posted pics by locating them in a special disk drive archive with proper labels as to which thread they relate to and also, they are saved at the new, reduced size, so that manipulation does not have to be repeated if they should be needed again. Backup is a once a week event here; we have had two massive hard drive crashes. That's enough to make anyone take notice! A separate, off line hard drive is used ONLY for that purpose.

Lance, your oak looks first rate to us; our only requirements were a preference for very straight grain, white oak and a very slight reddish cast, if possible, from our supplier in Virginia. We agree with DD, of course, the orientation of the heartwood and sap wood is certainly important on the originals of any size especially if laminations are used, as they have been through the ages. We haven't seen a wooden seacoast carriage yet which doesn't have a little warping, cupping, bowing or twisting of its beams. Those big timbers are more difficult to predict as to how they will move as they dry. The local artisans at or near the fort used their experience with ordinance, shipbuilding or timber frame and factory floor installation to cut the locally sawmilled beams as best they could and assemble the beams most likely to bow with the probable concave sides facing each other and secured by center-of-beam bolts usually close to, but on the outside of the center transom(s) and using the straightest grain for the upper carriage and rails, and less desirable wood for the platform.

Regards,

Mike and Tracy