Infantry Tank Churchill AVRE Mk.IV Tamiya 1/48


Introduction

 This is my 1/48 Churchill AVRE Mk.4 converted from Tamiya Mk.VII. Each part different from Mk.VII, such as the turret, mortar, hull front and side, were created by the 3D printer "Photon".


3D designing of the turret

 First of all, I designed the turret. The basic form of the cast turret was to Extrude and Intersect side and top view sketches with each other, then the edge was rounded off with Fillet. The diameter of the fillet in each part may be strictly different, but I could not think of any other design method. The basic shape and dimensions of the turret were verified with actual vehicle photographs and the drawings in Reference-5 that seemed to be reprinted from factory drawings.

The portion that connected to the circular cross section of the underside and the turret side was a bit different from the actual turret, because it couldn't be reproduced with my design skills. But it is easy to fix with putty, so there is no problem in practical use. By the way, while I was designing, I referred the 1/35 kit on the web. I found that some of the kits did not correct in the basic turret shape. Its front part is too flat.

As for the mortar, the accuracy was not so high in dimention, because it was determined from a slightly oblique photograph. If you are worried, use the Scale command to make it just the right size.



Sketches were extruded and intersected. After this, chamfer it with a Fillet and cut out the inside with shell to 1mm thickness.
I feel that the impression of the printed product is better when the design is slightly emphasized. The hatch groove is 0.35mm wide and 0.5mm deep in design. But it became narrow and sharrow in the print.

Differences of variation can be changed retroactively in the timeline.
The luggage box would be kit part.



Study of the turret

 There are variations on the turret. First, there is a difference in with / without the cuff at the bottom of the turret. Next, there are three positions of the ventilator : near the center, near the left end, left but slightly inward. There are two types of commander hatches : rectangular and trapezoidal. There are also some variations on antenna. The majority is that with the ring guard locates on the starboard side and no antenna in the center. The hatch fixture also has variations. See photos of actual vehicles because they are difficult to explain in words. The casting parting line is also slightly lower and slightly higher.


The Turret with cuff

 I also designed the turret with cuff. The part connecting the side of the turret and the lower ring-shaped part (shown with the red arrow in the lower image) is not designed as the actual vehicle. If you care about it, put putty on there seeing photos of actual vehicles.






Printing of the turret

 3D data was done, then I printed out the turret. The turret was placed horizontally in the Slicer and the layer thickness was 0.05mm. Stack marks were seen on the side of the turret and on the inclined surface on the upper surface, but considering the casting expression, the finish was almost practical. I was a little worried about stack marks on the periscope and the ring around the cupola. Therefore, next I tried 0.02 mm pitch. The stack marks such as cupola rings were improved, but marks on the side of the turret were more noticeable, and the reproducibility of the side hatch was poor. As a result, I decided that 0.05mm was good. The mortar should be printed in upright at 0.05mm pitch.



Theis is the first trial print. The layer thickness is 0.05mm, exposure time is 10 second.
Both mortars were printed in upright (The muzzle was top in a slicer, bottom in a printer.)



Mk.III turret

 I also designed the Mk.III steel plate welding turret. I hope somebody to use it. Stack marks are inevitable on the upper slope. Maybe it's better to sand off once and add detail parts from another print.






3D design of hull side

 Next, I designed hatches and attachments on the hull side. In order to determine the exact shape and dimensions, the side view drawings in the kit instruction was drafted, photos of the actual vehicle were traced, and the schematic drawing was created with Inkscape. That is the figure below. The blue line is Mk.VII. The turret design follows the same procedure. 3D design itself is not particularly difficult as long as the schematic is completed.




The side of the hull was designed integrally with the side armor plate. However, thin plate-shaped parts often curve when printed. Therefore, the hatche and attachments were designed to be printed separately for each part.

There are variations on the hull side as well as the turret. Many vehicles have additional armor plates on the sides. This is also cool, but there is concern about the above-mentioned curving problem. So I designed without additional armor. There are variations on the shape of the bolt on the attachment as well.



In the final design, the side armor plate is included. But each hatch and attachment can be printed separately.
Close-up of the hatch. It is easy to design, such as a dent around the bolt, but it is not reproduced when printed.



Printing of side parts

 The armor plate around the hatch was printed in one piece with the hatch and the piece would be replaced with that part of the kit.



The result is good enough for practical use. With such a small size, the curvature is hardly noticeable.



3D designing and printing of the hull front

 Then I designed the hull front. I measured the kit and made drawings with Inkscape based on actual vehicle photos. And I imported it into Fusion360 and designed it in 3D. At first, I thought that the basic shape and dimensions were the same as Mk.VII, but when I looked at the pictures in detail, I realized that they were different. The upper part of the front armor plate is vertically long and the upper surface has a gentle inclination angle. Furthermore, it seems that the slope of the upper surface of the hull coincides with the inclination of the cut line of the hull side armor plate.

Output was troublesome. Due to the fate of LCD printers, it is difficult to print a large size plane as a perfect plane. The reason is that a large flat part curves when fully cured. Therefore, reinforcement frames as shown in the image below were attached and cut off after curing. This frame resisted internal stresses that would curve.



Basic 3D design work is finished.
In order to prevent the occurrence of lamination marks, each plane is placed on the upper side in printing. Reinforcement frames need this height.

The back side looks like this. If the ceiling is slightly inclined by "moving the surface" (← fusion360 terminology), support is unnecessary.
Parts are printed, cut off unnecessary parts and lightly sanded.


As you progress the timeline through the end in Fusion360, reinforced walls will appear.


Designing and printing of the tracks

 Next was the track. The kit tracks were good enough, but I made them by myself. It is not interesting that they exactly the same as the kit tracks. So I chose the type with the short groove on the tread. This type is often seen in Mk.IV. The actual vehicle photos were imported to Fusion360 as background, and tracks were designed based on these. The pitch was adjusted to the kit. Otherwise, the drive sprocket will not fit.



Design work was finished. Pins for supports were designed.
This is the back side. The point is the dent on the back side of the tread. The thickness of the parts is designed at 0.3mm. Also pay attention to the differences in the parts where the wheels ride. Right and left side parallel is correct.

This is a printed state. The depth of the detail carving is the point of discrimination from the kit.
The dent on the back side feels good. The kit is not reproduced at all. The central hole is not open either.



Other parts

 Next, I designed the outside telephone, portable fuel cans, track rails, side lights and antenna mast. The antenna and side lights can be printed with ordinary resin, but they are quite easy to break. I recommend using the Tough Resin from SK-Honpo. (Sorry, I don't know it can be bought from outside Japan.)






The early Spud tracks

 Incidentally I designed spud heavy tracks too. I do not intend to use by myself, I hope someone use them.







File downloading

 This is the end of the planned Churchill-related 3D design. I hope you utilize them. Not only Churchill, but all 3D data files published on this site can be used freely and without charge by anyone, whether for personal or commercial use. In addition, introductions and links on other sites are also possible. Furthermore, data can be processed (improved, modified, added, remodeled) and used. You can use it as free materials. However, please contact me for commercial use. Also, if it has been processed, I hope you release it for free as well as me.

download link


Tough resin

 I tried to use the tough resin. This is good. I recommend. As you can see in the image below, it is elastic and does not crack when bent. (Of course, if you bend as much as you can, it breaks.) In addition, on the site of SK Honpo, the exposure time is 9-10 seconds as a recommended parameter, but I recommend 15 seconds. The image below is 15 seconds.



This elasticity is great. The antenna base itself is perfectly strong. At the time of output, the bottom plate is flat.
Closing up of the left image.



Construction



The 3D parts were designed as just size. So, the protruding parts of the kit were cut off.
The kit outside telephone were cut off because MK.IV is different from VII as for the position and shape. The phone would be 3D printed later.

The 3D parts was carefully positioned and glued with CA.
The hull top and turret were temporarily assembled. The periscope and ventilator arrangement in front of the driver's hatch is different, so this portion was cut out and replaced with plastic sheet.



Hull side

 3D printed parts were attached to the kit hull side. The escape hatch was set in a square cut out of the kit part. Other attachments were glued on the kit part. The shape of the armor plate behind the idler wheel is different from Mk.VII. This was made with a 1mm thick plastic sheet.



The backside of the 3D printed parts was sanded to be flat. Thin liquid cement is used for a wide adhesive surface. The hull side parts are not yet glued to the hull top.
The hull top and turret were tentatively combined.



Print and assemble of tracks

 I printed 3D designed tracks for actual use. As long as Photon worked well, most of the work was done while I was sleeping. But it was not easy. There was a step on the printed track. This was a physical phenomenon that occurs when a large plane suddenly appeared during printing. As a countermeasure, the print direction was tilted by 1°. I also added a support and made them thicker.

The next problem was that the yield rate was still extremely low. The phenomenon that the upper part was not output from a certain layer frequently occurred. This is a digital bug, so if this happened, I had to start over from works with a slicer. Also, it seems intuitive, the appearance frequency was high when the data of the STL file was large.

The third problem was that the idler wheels did not fit well on the printed tracks. The distance between the inner and outer holes was slightly shorter than the kit track. However, if the distance was expanded to match the kit idler, the road wheels did not fit. As a countermeasure, the adhesive part of the idler wheel parts was sanded to narrower the width.




This is the first test print. There is a crank-shaped step on the left side as viewed. This is where the track's side plane emerges just here.
This is a final print. After hardship, it was finally adopted. Tracks were printed in three parts: front, bottom, back.

The adhesive portion of the idler wheel and the drive sprocket were sanded by about 0.5 mm.
Assemble of tracks to the hull was completed. Rails (gray) somehow did not fit in size (a design mistake?). Then they were cut to fit.

As expected, the drive sprocket did not fit the shaft. Therefore, the shaft was cut and drive sprocket was assembled. After that, 3D tracks data was revised to fit.
The top and sides of the hull were glued together. Then the basic assemble was finished.



Surfacer

 At this stage, a surfacer was sprayed to confirm the assembly of the 3D printed parts.



Note the reproducibility of the details, especially the dent inside the tracks. Bolts have adhered to the side wall. Although separated in the data, it was caused by the "magnification" phenomenon inherent in LCD printers.
The reproducibility of the details on the front of the hull is good enough. The reproducibility of the horizontal groove of the driver's hatch is low. Later, the data was revisited.






Details



The mortar loading door was made of plastic sheet. The hatch grooves were filled with putty. The ventilator and machine gun were from the kit.
The outside phone is in this position. Spare fuel cans, spare tracks, etc. were 3D printed.

I felt that the front corner of the turret had less roundness. Therefore, the portion was rounded with sandpaper.
After sanding, cast surface was depicted with melted putty. The cast parting line was depicted by extended sprue and melted putty.

The mud shoot was made with plastic sheet. Wire ropes, conical shape rivets, hanging brackets for the side intakes, etc. were added.
Close-up. The wire rope was twisted copper wire for household electrical cords.


When the periscope visor was glued on the turret, it was too high. So the 3D part were trimmed. The rear rope attachment position of Mk.IV is about 7mm ahead of VII. The upper right image is the position of VII before correction. Probably because the length of the rope is the same, the front mounting position of VII has moved backward.



Detail works was finished.



Painting & weathering

 Basically, the method was the same as my previous work Mk.VII.



The base coat is black surfacer + red brown. The silicon barrier was sprayed mainly on the edge where paint was to be removed.
Basic painting is Mr.color C330 Dark Green + 20% white.

Tamiya acrylic Buff was diluted with soapy water and airbrushed. After this, Buff was removed by alcohol with tissue paper.
Paints on edges were scratched and removed. Excessively removed portions were touched up with a fine brush. Washing was applied with Weathering Master Light Sand or Sand with soapy water.

Flat Clear was oversprayed for fixing. Sail Color was airbrushed to the top of the model. Dark gray was airbrushed on edges and corners. Tracks were brush-painted with C22 Dark Earth. Washing was applied with Weathering Master Sand. Rub the edge with pencil powder. Equipment is brush-painted.



Churchill AVRE completed

 The white star and circle, the hull number were custom made dry decals. Finally my model was completed. Actually, I wanted to paint the unit marking, but the details of units to which AVRE belonged were unknown.

When I look at the completed image again, I think 3D print parts would be a satisfactory level for 1/48. Churchill Mk.III and IV are the mainstreams seen in recorded photos. I am glad if you can use my conversion parts effectively. There are also Mk.III turrets and early crawler tracks.


























3D design of M4 Sherman tracks

 In parallel with Churchill works, I designed 1/48 Sherman tracks. Tamiya kits have only T48 and there are few third-party parts. So I think it may be useful for many Shermania modelers. First, I designed the T54E1, which seems to be the most versatile.



T54E1 with duckbill

The back side looks like this. There is also room for rounding corners with Fillet, but I don't do that because the data become too heavy. Still heavy enough.
T62 (Download file of T62 has no duckbill)

T48 duckbill
T51

T54E2
T49

T56
HVSS T80

T84


M4 tracks download link

  • The drive sprocket should fit into the track before gluing the inner and outer parts together.

  • Still, tracks with duck bills are difficult. Therefore, it is advisable to sand the interfering part and spread the tracks up and down.

  • There is only a minimum number of spare tracks. Use Fusion360 to copy and paste or add the required number of each.

  • Spare tracks with end connectors have no tread detail due to the assumption that the tread is the adhesive surface.

  • Some types are only on the port side. The starboard side can be easily made by mirroring.

  • If you add a duckbill, insert the duckbill alone file into the design, break the link, and connect the duckbill body to the end connector body (on the appropriate timeline). On the other hand, if you want to remove the duckbill, delete the command that connects the duckbill on the timeline, and then delete the three sketches + extrusions that add detail.

  • As for Sherman V (M4A4), the hull is extended and tracks extended by 5 pieces. I designed the most popular T54E1 and T62. The method of adding or deleting duckbill is described above. Changing to other track types is actually easier than expected. In the timeline where the basic piece (shoe + end connector) is completed, insert the shoe which you want to change into the current design and replace it (first Intersect, then Join the same body(made by copy & paste)). If you cannot understand this explanation, e-mail me for any questions.


Drive sprocket



Early M3 type
Late type

Ring type





Different type duckbill with T54E1
WE210





Printing







Light guard











Referrence


1 Armor At War 7002 D-day tank warfare Concord
2 Armor At War 7027 British Tanks of WW2 (1) France & Belgium 1944 Concord
3 Armor At War 7028 British Tanks of WW2 (2) Holland & Germany 1944-1945 Concord
4 Armor At War 7068 British Armor in Sicily and Italy Concord
5 Mr.Churchill's Tanks The British Infantry Tank Mark IV Schiffer
6 New Vanguard 4 Churchill Infantry Tank 1941-51 Osprey
7 New Vanguard 136 Churchill Crocodile Flamethrower Osprey
8 Wydawnictwo Militaria 315 Churchill Warszawa







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