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Heng Long Metal Barrel Recoil BB shooting unit upgrade kit

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  • Heng Long Metal Barrel Recoil BB shooting unit upgrade kit

    A few days ago, I posted on a Heng Long Metal Barrel Recoil BB shooting unit for 3838 Pershing upgrade kit that I purchased for my 2005 Snow Leopard. I said that over 18 years, HL changed the cannon mantle mounting plate enough that the kit does not fit my Pershing. I contact the Toucan seller (build-for-u) to request a return. They got back to me in a few days after talking to the HL technical team. They came up with the idea of swapping the old mounting plate to the new unit. It works, but it is not a simple direct drop-in replacement. It took me 2 days of careful griding and cutting. I will post more pictures to describe the process in the next few days.

    The Metal Barrel Recoil BB shooting unit works with TK-6.0/7.0 without any electrical modification. Just connect the recoil motor to CN6. I have upgraded the Pershing with a TK-6.0S MB which works together very well.

    The Metal Barrel Recoil BB shooting unit is bulkier than the old BB only unit. I will do more test tomorrow to see if there is any interference problem in turret movement. In the pictures below, Left is the Pershing with the old cannon where the barrel and mantle are molded as one piece. On the right is the Pershing with the recoil unit. You can see the longer barrel.
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    I will like to mention that the seller, build-for-u, gave me the full refund and told me to keep the recoil unit. He asked for a positive feedback on ebay and that I keep them in mind for future business. I purchsed the Leopard 2A6 amd Sherman M4A3 from them the last 2 years. They have exceptional customer service.

  • #2
    The picture shows that the locating pins on the mounting plate changed location making the new mantle not compatible with the turret.
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    I swapped in Part 2 and Part 3 from the old tank to replace Part 1 in the recoil kit. Removing the BB unit from the mantle is simple. 2 screw for the old tank and 3 screws for the new. Give Heng Long credit for keeping the BB unit screw holes location unchanged for 18 years. Mounting the BB unit to mantle with the old mounting plate is easy. But combining the mounting plate with the turret is not. In the pictures below, new on the left and old on the right.
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    The recoil BB unit is bulkier in general and the recoil linkage on top interfere with the turret. The old mantle used 5mm LED diode, but the new mantle has a tall tube to slide a 3mm LED diode in. I removed material from the new namtle and the old turret by trial and error. I don't want to move too fast. Once the interferences were removed, the mounting plate clicked on the turret giving a perfect fit again. The Metal Barrel Recoil BB shooting unit works with TK-6.0S without any electrical modification. Just connect the recoil motor to CN6. The old turret with the new barrel moves like it used to. I paid slightly over $40 for the recoil BB kit and it is a very good investment.

    If you have a very old Pershing like I do, the upgrade is not recommended because it requires too many try and fit steps. If you have a newer version of Pershing, the "metal barrel recoil BB shooting unit" kit should fit as is and is highly recommended.​

    Comment


    • #3
      I have purchased a metal recoil BB unit for the Pershing and one for the Sherman. They are $40-50. I also purchased 2 generic recoil BB unit and one non-recoil BB unit.

      The picture below shows the old vs the new BB unit, just the BB shooting part.
      Click image for larger version  Name:	IMG_5177.jpg Views:	0 Size:	123.7 KB ID:	378355
      The old BB unit on the right has a long thick wall aluminum tube​ that fits inside the plastic barrel. The new recoil BB unit has a short thin wall aluminum tube that the barrel rides on. The new barrel consists of a plastic outer tube and an aluminum inner tube. The old unit has only one motor for BB shooting. The new unit has a recoil motor in addition to the BB shooting motor.

      I also purchase three generic BB shooting units, two with recoil and one without.
      Click image for larger version  Name:	IMG_5178.jpg Views:	0 Size:	112.4 KB ID:	378356
      It is interesting to notice that both generic units have 2 motors and one is for recoil. The only different is the missing short aluminum tube. The hole at the front of the recoil BB unit is smaller to accept the thin wall barrel riding tube. The hole at the non-recoil unit has the diameter to accept the old thick wall tube, but reduces to the new thin wall tube diameter half way in. I hope to try the recoil BB unit on the Tongde M60A1 and a HL Leopard 2A6.

      The old BB tube is 8.3 mm OD and 6.16 mm ID. The new recoil tube is 7.4 mm OD and 5.84 mm ID. Now, where I can find a piece of the thin wall aluminum tube to convert the non-recoil to a recoil BB unit?

      Comment


      • #4
        Ok! The M26 Pershing is back in one piece. Everything, new and old, are working. I am very proud that I did not break a single small part on the turret. The mantle and turret assembly is gap free like before. But after all the excitement dies down, one glaring fault starts to bother me.

        When I hand tested it, the barrel has a recoil travel distance of up to 1 cm. When it actually fires, it travels barely 1/3 of the distance. It looks terrible. Since it is a simple motor control by the CN6 triggering pulse, my only conclusion is that the trigger pulse is too short. I don't mind that it has no damping. But the short recoil is a major fault. It there is no easy way to adjust the pulse duration on the HL main board, the only option will be to add an external 555 timer circuit. Yes, it is easy to build, but it defeat my whole idea of keeping things simple.

        Whatelse can I do to improve short of replacing the recoil motor with a microservo?

        Comment


        • #5
          I looked at the recoil unit more closely. It translates the recoil motor rotation to the barrel linear pull back by a L-shape arm. The rocker portion of the L-shape linkage is very short. If I replace it with a longer rocker arm, will the recoil motor still be powerful enough to pull the barrel? How much longer the rocker arm needs to be? I may build a simple test rig using the generic recoil BB unit. in an assembled turret, the recoil pulling motion is invisible from outside. I have a few servo arms that I can borrow from my spare part bin for the testing.

          For those who have implemented a servo recoil, can I see a picture of your barrel pulling linkage? Much, much appreciated.

          Comment


          • #6
            Originally posted by keilau View Post
            I looked at the recoil unit more closely. It translates the recoil motor rotation to the barrel linear pull back by a L-shape arm. The rocker portion of the L-shape linkage is very short. If I replace it with a longer rocker arm, will the recoil motor still be powerful enough to pull the barrel? How much longer the rocker arm needs to be? I may build a simple test rig using the generic recoil BB unit. in an assembled turret, the recoil pulling motion is invisible from outside. I have a few servo arms that I can borrow from my spare part bin for the testing.

            For those who have implemented a servo recoil, can I see a picture of your barrel pulling linkage? Much, much appreciated.
            My idea of using a longer rocker arm does not work. The HL recoil motor already translates into linear motion. It pulls a plunger backward for about half a cm which is how far the recoil barrel will travel. I tested the HL generic recoil BB unit on the Tongde M60A1 and it works smoothly. With the guide from Rubicon99 post, I should be able to implement barrel recoil on the TD M60 easily.

            The Heng Long Sherman is another matter. When I open the tank, there is already a wire connected to CN6, but it is NOT for the cannon sound. The sound is there when the BB fires with or without the CN6 wire connected. But when I tried to test the HL generic recoil BB unit on this Sherman, with its recoil wire connected to CN6 and BB wire to CN10, the recoil motor did not fire! The Sherman has a TK-7.0 main board. More investigation tomorrow.

            Comment


            • #7
              Originally posted by keilau View Post

              The Heng Long Sherman is another matter. When I open the tank, there is already a wire connected to CN6, but it is NOT for the cannon sound. The sound is there when the BB fires with or without the CN6 wire connected. But when I tried to test the HL generic recoil BB unit on this Sherman, with its recoil wire connected to CN6 and BB wire to CN10, the recoil motor did not fire! The Sherman has a TK-7.0 main board. More investigation tomorrow.
              I am curious to hear more related to the Sherman as I am considering adding this feature to a Sherman build. Thank you for sharing everything and taking the time here.

              Chef

              Comment


              • #8
                After all the trouble I had matching a new mantle to an old turret on a Pershing. The Sherman should be a cake walk, right? I received the metal barrel recoil BB shooting unit for 3898 Sherman Tuesday late afternoon. Everything looks good and I expect the replacement operation to be quick.

                I got the recoil unit with the 75 mm cannon paying $20. The barrel is an well finished aluminum tube, same length and OD as the plastic cannon, but much thinner wall, unpainted. There is 105 mm varity, but the seller wanted $30 for just the Firefly barrel. For now, 75 mm is enough firepower for me. The 3 connectors from the left are recoil. BB shooting and turret infrared LED.
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                The Sherman turret is relatively small. I loosen the gun elevation motor and BB feeding tunnel. The old BB unit should come out easily, but it is stuck. My gentle persuasion pull is not working and I am concerned about breaking the turret. Will try again later. Any suggestion on how to disassemble the Sherman turret is appreciated.

                Comment


                • #9
                  keilau could you provide the link for the 75mm cannon for the Sherman please. I'm having a hard time finding one. Toucan only has the howitzer and long barrel easy 8 gun.

                  Comment


                  • #10
                    Originally posted by MrChef View Post
                    keilau could you provide the link for the 75mm cannon for the Sherman please. I'm having a hard time finding one. Toucan only has the howitzer and long barrel easy 8 gun.
                    I won this by a bid price. https://www.ebay.com/itm/23501775405...p2047675.l2557

                    The buy-it-now price is usually $5-7 more. Still very good compared to other tanks.
                    ※Henglong 1/16 6.0 7.0 USA M4A3 ShermanRC Tank 3898 Model Recoil Barrel BB Unit. Suitable For: Henglong 1/16 6.0 7.0 USA M4A3 Sherman 3898 RC Tank Model. Scale: 1/16. Color: Silver. Item Condition: New,Assembled.


                    Both of them are Toucan sellers. I dealed with them many times and found them reliable.

                    Comment


                    • #11
                      Originally posted by keilau View Post
                      The Sherman turret is relatively small. I loosen the gun elevation motor and BB feeding tunnel. The old BB unit should come out easily, but it is stuck. My gentle persuasion pull is not working and I am concerned about breaking the turret. Will try again later. Any suggestion on how to disassemble the Sherman turret is appreciated.
                      It took me a whole day to get the old BB/mantle off the Sherman turret. I tried a little, took a long break and tried again. I deliberately work slowly so that I will not break any plastic part. Putting it back together is a snap except for one piece of the BB feeding tunnel. Heng Long did a very good job designing the mantle turret interlock system. Once I got the new BB unit in the turret, it is a gapless fit.

                      It is 11 pm now. I will call it a day. I will continue the electrical connection and testing tomorrow and take some pictures too.

                      Comment


                      • #12
                        I went to bed after I tested fit the new cannon/mantle. There is a small piece of the BB feeding tunnel that I could not get off the old BB unit. It appears to be glued in place using some clear acrylic. Next morning, I tried to ply this piece off without breaking it.
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                        I took the new BB unit out of the turret which takes about 3 minutes. It's much easier once you learned how the interlock work. I broke half of the locating ring when I removed the small piece of the BB feeding tunnel which does not affect the functionality. I used a few small drops of RTV to fix the piece in place. Mechanical assembly of the turret is done. But electrical connections and functionality test should be next. Hope to complete before dinner time.
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                        Comment


                        • #13
                          Originally posted by keilau View Post
                          The Heng Long Sherman is another matter. When I open the tank, there is already a wire connected to CN6, but it is NOT for the cannon sound. The sound is there when the BB fires with or without the CN6 wire connected. But when I tried to test the HL generic recoil BB unit on this Sherman, with its recoil wire connected to CN6 and BB wire to CN10, the recoil motor did not fire! The Sherman has a TK-7.0 main board. More investigation tomorrow.
                          The Sherman is back together, everything work as they should EXCEPT the barrel recoil!!! The recoil BB unit was tested on another tank. I push the barrel in to verify there is no obstruction of movement. Was the trigger signal at CN6 turned off? is it possible? Do I get a faulty TK-7.0 main board? Any suggestion is appreciated.

                          Recoil is the only upgrade this time and the only function not working!

                          Comment


                          • #14
                            Originally posted by keilau View Post
                            The Sherman is back together, everything work as they should EXCEPT the barrel recoil!!! The recoil BB unit was tested on another tank. I push the barrel in to verify there is no obstruction of movement. Was the trigger signal at CN6 turned off? is it possible? Do I get a faulty TK-7.0 main board? Any suggestion is appreciated.

                            Recoil is the only upgrade this time and the only function not working!
                            Thank you to @SoCalBobS, his suggestion gave inspiration to try different function switches on the transmitter. The "G + B" function swith works for me. Now, the Sherman is barrel recoiling as it should.

                            Click image for larger version  Name:	image.png Views:	0 Size:	70.5 KB ID:	378747​​Why this function was turned off originally is beyond me.

                            Comment


                            • #15
                              Glad you got this sorted out. Your post will be good reference for anyone and when I do this mod for a Sherman..

                              Maybe it's the angle of the picture but the short barrel you have on the Sherman looks more like the 105 howitzer than a 75mm gun.

                              Comment


                              • #16
                                Originally posted by MrChef View Post
                                Glad you got this sorted out. Your post will be good reference for anyone and when I do this mod for a Sherman..

                                Maybe it's the angle of the picture but the short barrel you have on the Sherman looks more like the 105 howitzer than a 75mm gun.
                                yes, it is the 105 mm howitzer, not the 75.

                                Comment


                                • #17
                                  I have successfully add barrel recoil feature to a M26 Pershing and a M4A3 Sherman, both of which have the plastic barrel molded as part of the mantle. I used Heng Long tank specific "metal barrel recoil BB shooting kits". It is easier than building my DIY servo recoil and the result is pretty good. The Pershing metal barrel is painted in a brownish olive drab which is different from the dark green olive drab on the old Pershing. The Sherman barrel is bare tuned aluminum. My last step is to get both painted to the matching tank color.

                                  For my remaining tanks, a German Leopard 2A6, T-34/85 and the Tongde M60A1, which have independent barrel, I hope to use the much less expensive HL generic barrel recoil BB shooting kit and keep the original tank barrel.. It should be more challenging and more fun.

                                  It may be days, or even weeks, before I have results to report back here.

                                  Comment


                                  • #18
                                    Keilau, forgive me if you mentioned this earlier in the thread, but does the HL metal recoil unit snap back quickly then return slowly, the way it should? Or does it act like HL's original system that retracts the barrel slowly then snaps forward? Thanks.
                                    Twenty six tanks, and not done yet!

                                    Comment


                                    • #19
                                      Originally posted by SoCalBobS View Post
                                      Keilau, forgive me if you mentioned this earlier in the thread, but does the HL metal recoil unit snap back quickly then return slowly, the way it should? Or does it act like HL's original system that retracts the barrel slowly then snaps forward? Thanks.
                                      I am not sure what your question is. I have no illusion that a BB shooting would have the momentum of a real 105 mm modern gun in scale. Neither the small motor that Heng Long use nor the smaller micro servo would have the power to pull the barrel back in the scale recoil velocity nor in millisecond time. They also do not have the hydraulic damping of a real gun on rebound. In the Heng Long simple motor recoil kit, the recoil and rebound are symmetrical to my naked eyes. But they are reasonably fast to the naked eyes too, but far from scaled recoil and rebound speed. Are they realistic, NO. It recoils too slowly and rebound undamped. But is still 100 times more pleasing than the tank shaking recoil.

                                      It is possible to simulate the relative recoil and rebound speeds electrically. But I doubt that they will use the true momentum of a scale recoil speed which will simply be too powerful for a plastic model tank to handle. I do not have the HL TK-6.1/7.1 main board so I don't know how realistic is their implementation.

                                      Comment


                                      • #20
                                        Originally posted by keilau View Post
                                        NO. It recoils too slowly and rebound undamped.
                                        This is all I wanted to know.

                                        Twenty six tanks, and not done yet!

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