M-41A3 Walker Bulldog - ARVN Vietnam 1970s - Build

lmcq11 · Post by **lmcq11** » Tue Oct 09, 2018 1:56 am

Continuing previous post.

Then after the cut and finetuning, the outside teeth wheel is glued back on the shaft. You can see here the tube of Epoxy Steel. The two different gels of equal proportions need to be mixed thoroughly in a small pot for 1 minute with a stick before applying to the target area.

: 1/16 M41 Walker Bulldog tracks and sprockets

New sprocket on the left, original Mato on the right.

: 1/16 M41 Walker Bulldog tracks and sprockets

The two AFV-Model MLRS tracks can be assembled in about 15 minutes each (minus the rubber pads that should take about 1 hour each sides). They are well molded, good quality and are very smooth. Highly recommended.

: 1/16 M41 Walker Bulldog tracks and sprockets

The final step is to look for issues, correct, fine tune and polish the sprockets, up to a point.

: 1/16 M41 Walker Bulldog tracks and sprockets

: 1/16 M41 Walker Bulldog tracks and sprockets

I was curious about plan B, the resizing of the Heng Long tracks... and see how it worked. I devised a cutting process using 2 metal saw blades glued together with a 2.5mm spacer in between, and with a guide that would run along the central pin of the Heng Long tracks when I cut the tracks. The idea was to cut many links at the same time to speed up the process, and to make the cut identical on all the links. I have to say that it was a failure. The plastic of the tracks is not easy to cut. And I used old blades and it is probably the reason why the cut was so ugly and uneven. I had no inclinations to improve the process myself with new blades and a better jig, so I leave it to others to figure it out if they want to do something like that in the future.

: 1/16 M41 Walker Bulldog tracks and sprockets; Capture15.JPG (78.56 KiB) Viewed 4162 times

I ended up making one link by cutting the material with a hobby knife as shown. The 3 track parts are glued back together using a thick application of Superglue Gel. More superglue Gel is later applied in the gaps to form a strong and seamless joint. I do not recommend to use putty on the tracks, use superglue gel instead as a filler.

Making two links alike without some kind of standard process will be difficult. If the links are not totally identical, there will be many issues when assembling or running them. And there are usually quite a few links that should be discarded because they are not right (too short, not strait, various gaps), so I would recommend the purchase of an additional plastic set so that you can make at least 20 spares.

: 1/16 M41 Walker Bulldog tracks and sprockets; Capture16.JPG (86.13 KiB) Viewed 4162 times

The track and superglue gel is sanded mooth with a hand file and polished a bit. I was able to make the Heng Long track 34mm wide, compared to 32mm for the AFV-Model metal tracks. 1mm was sanded from each tips for a 7mm reduction in total. It good enough. Reducing it further would have impacted the integrity of the design. The Heng Long plastic sprocket width can then be adjusted and no reduction in diameter is required. I estimate it takes 5 to 6 minutes per link, adding up to about 15 hours of track work, and some mental heath issues if you go that way. After the Marder 1A1 track reduction, I will try any alternative before doing this again, but it is doable and much cheaper financially.

You can also notice the teeth hole design on both tracks. It is more realistic on the AFV-Model tracks. The Heng Long holes are too square and that is why their sprocket teeth are so narrow.

: 1/16 M41 Walker Bulldog tracks and sprockets

View of reverse side for comparison. No underside pits on the AFV-Model tracks.

: 1/16 M41 Walker Bulldog tracks and sprockets

With the AFV-Model MLRS track set on an M41, you end up with 24 spare links, which is great.

: 1/16 M41 Walker Bulldog tracks and sprockets

In conclusion, I recommend going with the AFV-Model tracks. The resizing of the Mato sprockets is a 5 hour elapsed operation. If you go with my metal grinding option, make sure to do it outside, with the metal dust going away from you and in the wind, and wear eye protection. Be careful.

A Plan C could be to buy the AFV-Model MLRS sprocket for use on the M41 (not accurate), or maybe transpose the MLRS sprocket teeth on the M41 sprocket hub, but I did not investigate that potential solution.

Regards, Louis

Will01Capri · Post by **Will01Capri** » Tue Oct 09, 2018 2:51 pm

Very good work, the sprocket sizing was interesting and is good to do in iterative steps.
We should be able to easily calculate the required sprocket diameter based on the pitch of the pins and the distance from the centre pin to the mating surface on the sprocket calcualted as an offset.
If you can draw in CAD then the idlers could be EDM wire eroded to the correct shape. Yes it is expensive, but maybe something for the future.
Keep up the great work

BarryC · Post by **BarryC** » Tue Oct 09, 2018 5:01 pm

OK Louis, just WOW!

Don't you just love it when "a plan comes together"?

Barry

wibblywobbly · Post by **wibblywobbly** » Thu Oct 11, 2018 2:17 pm

This build is mind boggling, but as someone who always loved the Bulldog, but not the inaccuracies, I am in awe of your dedication to the cause. Brilliant work!

mcovalsk · Post by **mcovalsk** » Fri Oct 12, 2018 12:50 am

I've been after building an accurate M41 for some years now. I made a first attempt several years ago that was good but not enough and I sold it. Right now I'm working in another one, from time to time in middle of others.
I want to say you, that I'm a very experienced modeller with more than 55 years breaking all kind of ... plastic, wood, metal etc, and I have seen lot of amazing pieces and modelers, but your qualify among the top five for sure!
It's not the job itself but you was brave enough to correct the turret!
Modelling in the level we do in this and other forums ( and scales) it makes us as builders, I consider myself a good builder, but to face a so difficult job in a US$100 model, with a difficult plastic to work with, without afterparts others than what you could scratch, it makes the difference between us.
Man you have all my admiration, and now I'm going to leave my M41 project in the trash

Mario

PainlessWolf · Post by **PainlessWolf** » Fri Oct 12, 2018 3:45 am

Good evening,
I've been enjoying this Build due in no small part to Louis attention to detail on the Walker ( and the other builds he has worked on as well ) Along with Barry and a very few others, he inspires us to attempt more than we might be comfortable with to bring that extra bit of realism to our running vehicles. I do not consider myself among any top modelers. That does not stop me from enjoying what I am doing nor should it any others. Enjoy the level of skill set that you have achieved and don't be afraid to push the envelope a little. Once again, the key to anything is to enjoy what you are doing. We're lucky to have top modelers on the Forum. Enjoy their work ( their fun ) and learn from it. I think that they would be disappointed if people were discouraged from doing their own work ( and having their own fun ). I certainly have faith that great examples, great achievements of any hobby or discipline are there to inspire us to better things. Enjoy your work ( fun ) my friends. Following along.
regards,
Painless

lmcq11 · Post by **lmcq11** » Fri Oct 12, 2018 6:01 pm

Hi everyone, thank you for your interest

Will01Capri wrote:If you can draw in CAD then the idlers could be EDM wire eroded to the correct shape.

Oh, I am trying to keep things simple. As you can see, I use simple hand tools that anyone have in their house. I plan to look into CAD and 3D printing when I am retired from IT. As I spend all my work days on a computer, I am actually looking to get away from it on my hobby time.

BarryC wrote:Don't you just love it when "a plan comes together"?

Yes, I am surprised as to how well the build has gone on every components. It has been 6 weeks since I started and the construction is almost finished.

mcovalsk wrote:Man you have all my admiration, and now I'm going to leave my M41 project in the trash

Hi, thank you for your kind words. I've been in modelling myself for about 46 years; plastic, wood, RC tanks, RC aircrafts, RC boats... I think this build is my 55th 1/16 tank. Never sold one so the house is full of them. Once you build your 4th Tiger, 12th Sherman, or your 4th Panther, this is what we have to do to keep being challenged.

Below is what's left of my first attempt at building an accurate M41. The method i used to reduce the fenders, from the inside, went badly and was too complicated. It was in the junk yard for quite a few years. I used it for target practice for some of the work I did on this build. It is better to test some modifications before doing it for real.

: Heng Long M41A3

PainlessWolf wrote: Once again, the key to anything is to enjoy what you are doing

Thank you Painless. I fully agree. I get most of my excitement from experimenting stuff I never did or saw before. I was bored with my last Tamiya kit... But I did 4 Ludwigs kits in the past year and my scratch building skill seems to have improved a lot. It opened up a brand new modelling world to me where I am no longer limited by what is available on the market.

Best regards,

Louis

lmcq11 · Post by **lmcq11** » Fri Oct 12, 2018 6:07 pm

wibblywobbly wrote:This build is mind boggling, but as someone who always loved the Bulldog, but not the inaccuracies, I am in awe of your dedication to the cause. Brilliant work!

Thank you. Yes, after so many years of seeing the Heng Long M41 everywhere, we almost lost the knowledge as to how an M41 should actually look like.

: M41 Walker Bulldog 1/16 RC modified

Regards, Louis

lmcq11 · Post by **lmcq11** » Fri Oct 12, 2018 8:00 pm

Hi, here are the electronics and gearbox

Layout of the interior with Clark TK-22 and speaker at the front, Flysky receiver on the right. No Smoker.

Take note that on a TK-22 with 10 channel Flysky remote, I connected the wires as following

FS Channel/TK-22 Channel
------------- -----------------
1 / 1
2 / 3
3 / 2
4 / 4

You can also see the recoil unit servo and the small connector for the gun flash unit at the front.

: HL M41 1/16 electronics and gearbox

The standard Heng Long M41 gearbox is too high for a model with reduced height. Below is a Heng Long Jagdpanther 3869-1 gearbox that you need for such build. It is low and has the long shafts that are required for the sprockets. For 24$ with free shipping, this is the cheapest alternative. And it just falls into place with no modifications. Only two anchor holes for the left gear need to be prepared, the others are already aligned.

: HL M41 1/16 electronics and gearbox

I could not figure out why the Heng Long tail lights LEDs were not working with my head lights. As soon as I connected the tail lights to wire 2 and 3 on the CN9 connector that already had the head lights connected, the head lights stopped working...Some kind of incompatibility. I therefore cut the wires for the HL tail lights and reused the 3mm red LED that came with the same commercial lights set as the head lights LEDs. I simply glued the new 3mm LED to the back of the HL 5mm LED plastic. It works, it is a bit less brilliant now, which is good anyway.

: HL M41 1/16 electronics and gearbox

Overview of the hull interior, nothing fancy

: HL M41 1/16 electronics and gearbox

Despite the turret rework and lengthening, it is important to keep the main screws aligned. This facilitates construction and ensures that the recoil unit correctly lowers into the hole in the middle of the ring.

: HL M41 1/16 electronics and gearbox

CN9 connector arrangement on the Clark TK-22.

cable 1 is coax MG -
cable 2 is head/tail lights -
cable 3 is coax MG + and head/tail lights +
cable 5 and 6 are for gun elevation
cable 7 and 8 are for turret rotation

: HL M41 1/16 electronics and gearbox

I designed a locking mechanism so that the front hull can be closed tight without having the put the 2 screws at the front. This allows the bottom front holes to be plugged and sanded smooth for a seamless front hull. The top of the hull is held solidly in place with the 4 central screws.

: HL M41 1/16 electronics and gearbox

About 2mm needs to be removed from the gearbox shaft is order to align the sprocket with the roadwheel, a 10 minute job with a metal hand file.

: HL M41 1/16 electronics and gearbox; Capture8.JPG (96.49 KiB) Viewed 4135 times

Tracks and sprockets are installed, still without the rubber pads until after painting. Everything works perfectly, I am very satisfied with the AFV-Model tracks, highly recommended. The track is tight and an Henntec adjuster is absolutely required. The Epoxy Steel job on the sprocket seems to be holding quite easily. Having closely realistic metal tracks with rubber pads for this tank is really a big improvement over any past options we had.

: HL M41 1/16 electronics and gearbox

: HL M41 1/16 electronics and gearbox

lmcq11 · Post by **lmcq11** » Fri Oct 12, 2018 9:05 pm

Continuing with the hull

The AFV-Model/TankModellbau M26 shackles look good. There is even I small hole to put a locking bolt at the end of the pin, something I need to figure out how I will do that. They look much better than the HL part.

: Heng Long 1/16 M41 walker bulldog reworked hull

Overview of the hull with the AFV-Model tracks on. They will of course look much better painted with the rubber pads on. I determine these are the early MLRS/Bradley tracks, of the same family of tracks as those for the M41. These are not the later "Big Foot" MLRS/Bradley tracks.

: Heng Long 1/16 M41 walker bulldog reworked hull

: Heng Long 1/16 M41 walker bulldog reworked hull

You can see I have installed one of the Shapeways hub with 4 pins on one of the road wheel. There seems to be something wrong with them. Maybe too large, too long, I do not know yet. Before I install more, I will investigate the situation further. I have learned not to blindly trust the design and dimensions of Shapeways parts. Despite all the best intentions of the creator, they need to be verified for accuracy.