3D Printing Cannons in Resin

[allanyed]

 Hi Srenner

I think Greyhound (20) 1720 carried 6 pounders, probably Borgard pattern,  which were issued on new ships from 1716-1724.   Is there a reason you want to mount 18 pounders on such a small ship? 

 

Allan

[Lieste]

I didn't even notice the 18pdr request as it was before the ship identification.... yeah 6pdrs are more appropriate (which is neat as that is the Lavery data set).

[Srenner]

No reason.. I don't really know the size so I wiki searched and it said 18 pounders were standard for frigates. I wasn't looking at the right info

[myMADNESS78]

Thanks so much for sharing, Ron. These cannons are great!

Edited February 8 by myMADNESS78

[Lieste]

On 2/7/2024 at 8:28 AM, Srenner said:

...

Okay, dug out an old spreadsheet which among other things had the data from the referenced page (note that the tabulated data doesn't always agree with the 'proportions' from calibre provided, so ... yeah. That might be a problem.

Lengths:
AT Nominal length 96" 25+15/16 cal 95.97"
AG Fore Part 48" 12+31/32 47.98"

GN Mid Part 19.2" 5+3/16 19.19"
NT Hind Part 28.8" 7+25/32 28.79"

AD Head with Astragal 12.75" 3+7/16 12.72"

AR Bore 92.3" 24+15/16 92.27"

RT Resistance 3.7" 1 3.7"

TX Cascable with Button 7.4" 2 7.4" 

WX Neck & Button 4.81" 1+19/64 4.80"

LT Rear of Trunnion to Base Ring 41.14" 11+1/8 41.16"

IK Trunnion Length 3.7" 1 3.7"

AX Length OA -- -- 103.37"
TW Breech face -- -- 2.60"

 

Moulding Breadth with Freize
AB Muzzle 1.12" 5/16 1.16"

CD EF PQ Astragals 0.75" 13/64 0.75"

GH 2nd Reinforce 2.37" 41/64 2.37"

NO 1st Reinforce 2.37" 41/64 2.37"

ST Base Ring 2.62" 23/32 2.66"

TV First Cascable and Stave 1.43" 25/64 1.45"

VW Second Cascable and Stave 1" 17/64 0.98"

QS Plain Freize 3.7" 1 3.7"

PG Second Reinforce Plain Freize 2.77" 3/4 2.78"
-- Neck Stave -- -- 0.17" (not explicitly listed in the data at all)

Thickness of Metal

lm Over Vent 4.62" 1+1/4 4.63"

no Behind 1st RF 4.39" 1+3/16 4.39"

rs Before 1st RF 3.93" 1+1/16 3.93"

tv Behind 2nd RF 3.7" 1 3.7"

yz Before 2nd RF 3.24" 7/8 3.24"

3.4 Muzzle 1.85" 1/2 1.85"

 

Moulding Prominence Over Metal

ik Base Ring 0.8" 7/32 0.81"

pq First Reinforce 0.37" 3/32 0.35"

wx Second Reinforce 0.37" 3/32 0.35"

1.2 Head 1.8" 31/64 1.79"

 

Semi Diameter

gh First Cascable Stave 4.5" 39/32 4.51"

ef Second Cascable 2.65" 23/32 2.66"

cd Neck 1.85" 1/2 1.85"

ab Button 2.24" 39/64 2.25"

LM Trunnion 1.85" 1/2 1.85"

Sorry no diagram, but landmarks are consistent, and with reference to an Armstrong gun the necessary order and arrangement should be easy to find. Exact form of mouldings I don't have (I was more interested in internal ballistics, and the line of metal angles). This 8ft 6pdr might or might not be the most suitable Borgard pattern, but it is the only example I have explicit parameters for. I would use the calculated inches (and retain the 64th of an inch / closest 64th of calibre if I were to recompute) - The tangents won't 'flow' with the proper form if the truncations are inconsistent. That said, there are no *very* large differences, aside from the neglect stave of the neck. The lengths are likely improperly stated as multiples of calibre (for the most part), rather than proportions of gun length and 'a calibre' for the trunnion placement and/or 2nd reinforce. Thickness and mouldings.. Breadth of mouldings might be either proportion of calibre or of gun length (French 1786 is fixed per calibre for multiple lengths, Armstrong a fixed proportion of gun length... Moulding prominence could go either way too).

Good luck with figuring out what goes where.

 

Edited February 8 by Lieste

[Srenner]

Have you got the similar table for a pattern already done like a Armstrong 6 pounder 72 to help me work out what goes where?

[Lieste]

Start with the line AT which is the centreline of the gun, forward of the breech ring. Extend it backwards to AX for the cascable and button. Set off a construction line half calibre above and below this line for the bore.

Starting at the muzzle 'A' (bore plus thickness 3.4) the first landmark is AB - this is the muzzle moulding which includes a muzzle listel (step) an 's-curve' a second listel. I am unsure on the muzzle swell location (1.2) but for many similar designs it is at 1/2 calibre from the muzzle face.

The next landmark is AD which is the breech side of the muzzle astragal at the neck (cd), the Astragal CD lies to the muzzle side of that landmark.

The next landmark to set is AG - the length of the chase. where the height 'below and above' 2nd RF are to be set off as construction line. Join the thicknesses 'cd' at D and 'yz' at G for the chace construction line. On the chase there is a plain surface between G and F of the Freize width, the EF is the chace Astragal and listels (two smallish rectangular sections sandwiching the Astragal prominence (a semi-circular section ring).

GN sets the position of the front edge of the first reinforce, with again, two heights before and behind the end of the reinforce. Join 'before' the first and 'behind' the second to give the surface of 2nd reinforce.

RT sets the position of the end of the bore, and of the 'thickness at the vent'. Extend a line from 'behind' 1st reinforce through 'thickness at the vent' to the end of first reinforce at the position of 'T' for the surface of the 1st reinforce.

The 2nd Reinforce ring (and listels) occupy about half the distance GH, and are at the 'breech-ward end' of the 'step' with a prominence above the surface of the reinforce, and the 'muzzle' side of the reinforce ring being an 'S' shaped curve from below the fore listel to the chace (unsure if the moulding has a step or a tangent transition to the chace, it doesn't specify in my notes).

1st Reinforce Ring is similar within NO, with the end of the first reinforce at N from the second reinforce to the ring and listels prominent above the surface in the half towards the breech.

The base ring is between ST, again, roughly half ring and listel (At the end 'T', and half moulding falling off to the surface at S.

The Frieze is ahead of S a distance of QS, with the vent astragal PQ of prominence of the Astragal and a pair of listels.

Behind the base ring there is a listel or radius (diagram unlear), then two 'frying pan' shaped, curved 'cascables' which have some variety of listel or stave between each segment (diameter given - unsure if the outer or inner one) The diameter of the neck is the calibre, and button rather larger, curves are tangent to each other, and meet the neck stave (probably the same diameter as at the button).

Aside from the absence of the button astragal the general arrangement is similar-ish to the 8ft (or 96") 6pdr Armstrong, but with some differences in proportion.

For the muzzle swell there is a (smallish) radius for the swell set off something like... From the top of the second muzzle listel, to the 'tip of the muzzle swell' a line. At right angles from the 2nd muzzle listel to the position of the swell to fix a point 'Z'. Double the distance to 'Z' from the muzzle swell for the centre of the swell radius.

An arc thrown through the neck surface at 'D' and tangent to the muzzle swell curve with a specified radius (or with a centre at the position of D but well 'outside' the gun, as we have no such radius specified here) will give a curve from the neck, continuously through the swell to the muzzle mouldings.
 

[Lieste]

Disregard comment above about 'neck semi-diameter' - this is the neck of the button and is a solid diameter of the calibre. The Neck of the muzzle astragal is the same thickness/diameter as the 3.4 muzzle face

[allanyed]

9 hours ago, Srenner said:

Have you got the similar table for a pattern already done like a Armstrong 6 pounder 72

Your ship would have carried Borgards when launched but as she lived for over 20 years could have been re-armed with Armstrongs.    If you want to go with

as- launched I imagine if you get hold of the Armstrongs you can file off cascabel ring and the "2" on the George II cypher which to me are the only really noticeable differences at small scales.   Either way, Ron has done outstanding work and has allowed us to fill the huge gaps in cannon patterns and sizes from kits and after market suppliers.  

 

Allan   

 

[thibaultron]

On 2/5/2024 at 11:03 PM, Srenner said:

Hi... do you have an stl of a british 18 pounder long gun circa 1720? I can do my own Cypher but just want the basic shape. Thanks

I'm working on that era cannons now, the Bogards 1716. I'm in the process of developing the cypher.

 

I have the slightly earlier Brown Pattern done. I don't know which your model would have carried.

[thibaultron]

On 2/8/2024 at 9:08 PM, Srenner said:

Have you got the similar table for a pattern already done like a Armstrong 6 pounder 72 to help me work out what goes where?

I'm working on the 6 Pounder Bogards now. Will have your cannon within a week.

[thibaultron]

The Bogard Cannons have the following sizes, at on the drawing I have:

 

4 Pounders:

     84"

     90"

6 Pounders:

     90"

     96"

     102"

9 Pounders:

     96"

     102"

     108"

12 Pounders:

     102"

     108"

     120"

18 Pounders:

     102"

     108"

     120"

24 Pounders:

     110" (108"?)

     121" (120?)

32 Pounders:

     108"

     114"

     120"

 

The 24 Pounders may be mis-dimensioned on my 2D drawing.

[Lieste]

I don't have a good table of dimensions for the pattern, but I would expect - from the pattern of every other piece that it would be a 6" multiple for length - as 11x is more likely a read from 110 - than 10x - I'd perhaps favour 114 and 120, but ymmv, and perhaps they have an 'odd' size like the (much) later 63cwt 32pdr, which is a full 1" longer than the 'ordinary' 55.5/56cwt type. <shrug> If these are parametric and it is not too awkward to add an extra length I might suggest doing both 108 and 114 for the 'short' 24 with a note and letting the end-use select which to print. Unless there is good documentation which specifies what the design length would be (it is possible that variation from mould to mould occurs in these individually created pieces and a measured piece is an inch or two longer, or (less likely) 4" shorter than the pattern... or the dimension is taken off a handwritten list with an error in copying, or the list compiled with error). Some variation in length can be a feature and not a bug, so long as the proportions comply with the rules in 'coarseness'. Later guns are required to be more consistent than the earlier patterns. and after the mass proof failures of the 1780s/1790s the manufacturers and ordnance board was much more enthusiastic about eliminating defective ordnance before the proof firings started, as the 'heightened' testing regime for a batch with failed guns under proof in it often caused a significant fraction or all of a found day's production to be wasted. The slower burning of the older powders (even with the larger powder sizes) were a bit more forgiving of variations from the required strength and proportion.

[thibaultron]

Here is an example of one of the Bogard cannons. I've drawn one in each size to check that the cyphers curve properly on the barrel. I'll draw the rest now. This is an 18 Pounder. The line on the barrel, by the cypher, is an artifact of the drawing, it would not show on a print.

 

[Srenner]

I printed off the armstrong pattern 6 pounder 84 with the george 2 cypher and had quite a few print fails across 20 barrels. Wondering if the resin temp was a bit low - it was only about 22 degrees today. Anyway - some of them turned out ok. Should I tilt the barrels further when I print?

 

[thibaultron]

Earlier in this thread I detailed my setup for the supports. I orient the cannons at 45 degrees (gives best detail), with the barrels pointed with the muzzle directed away from the build plate. This allows the resin to sort of drain away from the print, during printing. This also gives a better base attachment to the solid breach area, rather than the thinner hollow muzzle.

 

I use Lychee for my slicer program. After angling the barrel, I raise the part up 5mm away from the plate. I use the Raft Form baseplate. The angled walls of the raft allow for easier prying of the parts off the bedplate. I see that you did use the raft in your prints. You don’t state the scale, so that makes this last a little difficult. From about 1/24^th to around 1/64^th, I use the automatic support feature with medium supports. After that finishes, I go back and manually place two heavy supports under each of the two trunnions (one at the trunnion to barrel area, and one at the tip). I then see if there are any more yellow areas shown, and may add more medium supports to those areas. For smaller scales, I use light supports, with medium ones at the trunnions.

 

 This graphic shows a 1_24^th scale 32 Pounder cannon, after the medium supports have been auto-generated.

 

In this graphic, I have added one of the heavy supports to a trunnion tip.

 

 

I print with a layer height equal to the pixel size on the printer. In my case my printer has a 35um pixel, so I used a 35um layer height. Yes, the 45 degree and smaller layer height take longer, but you are printing these for yourself, so just leave it overnight to print. I have an AnyCubic Mono 4K printer. If yours is different, the manufacture’s site generally has the pixel size listed somewhere in the specifications for that printer. Each layer height requires a different exposure time. So, exposure times for the standard 50um layer height will be too long for a 35um layer.

I’m going to assume that the temperature is 22C. If it is 22F, yes that is way too low. 22C or 71F should be OK, depending on the resin. Have you calibrated your exposure times? There are several YouTube tutorials on the calibration procedures.

 

It generally takes me a couple of test prints to get the supports right, and I always print as many as the printer will hold. I still get some misprints, so this gives more chances to get good ones you can use. Look at the failure areas and add supports at the failure points. You may also need to bump up the exposure times slightly.

 

3D Resin printing is more of an artform than science, to get the settings right. So, some experimentation is often needed.

 

I leave the cannons on the supports, if possible, while cleaning them, with small wood or plastic rod run down the barrels to force as much of the resin out of the barrels as possible, after the first cleaning, then I run another cleaning cycle.

 

I also use my smallest micro drill to clean out the touch hole, before the second cleaning, for larger scale prints.

 

Remove the supports before curing, as they will break away cleaner now, than once hardened. I let them dry overnight, before curing. This lets all the cleaning solution dry from those small interior areas. If there is still solution in when you cure, it can leak onto the outside surfaces and mar the surfaces.

 

If all the above still does not fully fix your problems, try raising the temperature in the printing area.

 

I am just a beginner, myself, in 3D printing, so I can not offer any better advice.

[thibaultron]

I'm about 3/4s of the way through the Borgad cannons. Here is a graphic of one of the 12 Pounders.

 

Here is a closeup of the King George 1st cypher.

 

 

 

[chris watton]

Nice thread.

 

I have found that I have a 99% success rate by positioning the barrels almost vertital (with slight tilt). This minimises the areas for the supports, as commercial products would not look too great if the customer had to file/sand off all the support 'poc marks' the whole length of the barrel. It may take longer to print, but this is offset somewhat by the increased number of barrels that will fit on the build plate, and they will have much less clean up.

 

Also, in the Winter months, I will have my oil heater on, and I have the tub of resin and build plate sitting on top of the heater overnight, so in the morning, both are nice and warm.

[64Pacific]

I have really been struggling with my resin printer lately; I believe the issue to be trying to print too small without first trying bigger models. I wouldn't mind trying one of these cannons and following through with this tutorial. Are there drawings available for the base and details of the cannons? I wouldn't mind making a model for my desk of one of these cannons.

[Srenner]

Quick question barrel tilted down away from the build plate isn't it... not towards it

[thibaultron]

The only drawing I have for the carriages is this one.

 

Armstrong Frederick Pattern 1760.DXF

 

I've been concentrating on the cannons.

[thibaultron]

Not all 3D resins are brittle. If you need a more durable resin for a project, here is a link to a model railroad Podcast, where one of the members is 3D resin printing an entire HO scale diesel locomotive, and discusses the durable resins he uses. He crushes and earlier print with a standard resin with his fingers. He then shows the more flexible body he printed with the better resin. The discussion starts at about minute 25.

 

 

He used:

Siraya Tech Fast Resin for body, which is a bit flexible, and their Blue Resin for the gearboxes for the power trucks. The Blue is strong, but stiffer, as is needed for a gearbox you want not to flex.

[64Pacific]

Awesome, thanks for sharing the drawing! When I am back at the computer in the morning I will take a look.

[allanyed]

On 3/9/2024 at 6:08 PM, 64Pacific said:

Are there drawings available for the base and details of the cannons? I wouldn't mind making a model for my desk of one of these cannons.

Are you looking for Borgard, Armstrong,  Armstrong Frederick, Blomefield or some other cannon pattern and carriages?  These were all produced over various periods in the 18th century with obviously some overlap/carryover.  Ron has been doing a fantastic job of making the barrel STLs available for 3D printing.

 

The carriages also varied in design and construction. Examples follow.  Chart of carriage dimensions from 1768 and 1775 are also attached below.

Allan

 

1775

 

  

[64Pacific]

Thank you for sharing these tables and the drawing. I am not too particular on the type or style of cannon as it won't go into a ship. Rather it is a small project with the intent of re-igniting my desire for using the resin 3D printer with the added benefit being something neat to put on the shelf afterwards.

[allanyed]

64

I did a couple desk top Armstrong Fredericks in 1:24 and it made for a nice change of pace type project.  Give a shout if you want the carriage drawing.

Allan

 

Edited March 14 by allanyed

[64Pacific]

On 3/14/2024 at 8:44 AM, allanyed said:

64

I did a couple desk top Armstrong Fredericks in 1:24 and it made for a nice change of pace type project.  Give a shout if you want the carriage drawing.

Allan

 

Thank you for the offer, I will try to send you a message... Your cannon looks really great, it looks like it will be a fun project and a nice break from my plastic tug and old rusty truck.