Metal Origins SdKfz 234/2 Puma

[silversurfer1947]

I stripped the motor out and moved it in its mount to the opposite extreme from that indicated in the instructions and refitted it. Opened the throttle, and after a short pause (as per the elmod instructions,) lo and behold, the wheels started going round.

There is a lot of noise from the gears but there are also a lot of gears! There is the transfer box plus 4 bevel gears for each axle. I reckon a total of 35 interfaces all told. Hopefully, once they have all bedded in over time, the level of noise will decrease. Alternatively, I can always turn up the volume on the speaker.

Three main things remain to be sorted out .
1. The turret drive
2. Precisely where I am going to put the elmod board.
3. Talking very nicely to a man I know with a 3D printer about a recoil mechanism.

Then I can fit the barrel and put the whole thing together.

[silversurfer1947]

You guys out there have been very helpful to me in overcoming my problems with this build. I am going to prevail upon you for some more help ,please. I have two-fold problem with the turret rotation. The first is that the worm drive won't engage with the toothed gear. I am thinking about how to overcome this. The other problem I have discovered is that when the worm drive does engage (by me holding things together), the clutch in the gearbox cuts in. There is obviously far too much friction between the turret and hull top. Unlike my Tamiyas, there are no bearings - it is plastic on plastic. I realize that Heng Long, Taigen etc don't have bearings either, and they don't seem to have to problem. I would love some suggestions as to how to overcome this. I have tried releasing the screws which hold the toothed turret ring to the turret but the ring then wobbles about.

[tomhugill]

You guys out there have been very helpful to me in overcoming my problems with this build. I am going to prevail upon you for some more help ,please. I have two-fold problem with the turret rotation. The first is that the worm drive won't engage with the toothed gear. I am thinking about how to overcome this. The other problem I have discovered is that when the worm drive does engage (by me holding things together), the clutch in the gearbox cuts in. There is obviously far too much friction between the turret and hull top. Unlike my Tamiyas, there are no bearings - it is plastic on plastic. I realize that Heng Long, Taigen etc don't have bearings either, and they don't seem to have to problem. I would love some suggestions as to how to overcome this. I have tried releasing the screws which hold the toothed turret ring to the turret but the ring then wobbles about.

It's a fairly small turret which I guess you don't need to manually spin to get into the tank, so I would just glue up the clutch. Other options might be a dry lubricant but the turrets not big so maybe the mechanism needs looking at?

[Max-U52]

There is obviously far too much friction between the turret and hull top.

I have a method that's worked well for me with regular tanks (one of the few that I don't have a video for). On both of the mating surfaces I first use a rough sandpaper, like 60 or 80 grit, very carefully by hand, just dragging it slowly in a few passes over the circle where contact is made. Then I go over that by hand with fine paper (400, then 600 wet), being careful not to totally remove the 60/80 grit scratches. I do this to both surfaces, then with a short bristled fairly stiff paintbrush I rub graphite powder into the areas. I use the graphite powder they sell for those little pinewood derby cars (popular in the US with the Cub and Boy Scouts). The scratches from the first paper help to hold the powder in place and the smoothly sanded top surface provides a good gliding action.

Another method I wondered about but never investigated would be some kind of teflon impregnated paint for the two mating surfaces to provide smooth travel. I don't even know if they make such a paint, but thought it might be worth looking into and then never got around to it.

On a totally unrelated topic, I used to turn up these little brass coins and stamp them with the word "Tuit" (pronounced too-it). Then when I got tired of hearing someone tell me they'd "get around to it" I could hand over the coin and say, "There, now you've got a round tuit so get off your duff and get to work".

[silversurfer1947]

I used to use graphite powder in the days when I was taught to pick and repair or refurbish locks. Made a terrible mess if you sneezed at the wrong moment!

[silversurfer1947]

Not having a good morning. I decided to run in the various gears, as suggested in the instructions. Fired everything up, having blocked up the chassis. Initially, the wheels were bouncing up and down on their own, but start to settle down as everything started too mesh properly. After about 5 minutes, one of the wheels stopped rotating. A quick inspection indicated that the grub screw securing the inner drive shaft has come loose. I thought I had given all the necessary part a good enough dose of thread lock, but it looks like I missed one. It has now become apparent that what was a straightforward process in assembly is a real swine when it comes to just getting retro access to one specific part. I really don't want to have to reverse the whole assembly process. I have managed to drop the relevant gearbox and axle assembly down, but a couple of other parts fell out in the process.

Taking a break with a mug of freshly brewed coffee, before I gird up my loins and return to the fight.

[HERMAN BIX]

Without knowing how those shafts are configured, if they are all simply round shafts with the gears being round holes with grub screws, all the thread lock in the world will not save you !
Best to file or grind a tiny flat or dimple on the section of the shaft that the grub screw engages, and once the screw is made home, that gear is there for good.

[silversurfer1947]

Fortunately, the shafts all have the necessary flatson them. I just didn't get it right. It makes it more frustrating that it was my own stupid fault. This time there will be lashings of thread lock!

[Model Builder 4]

Morning Richard, I'm not sure if you have fixed the turret rotation friction problem yet so I thought I'd mention what I use to remedy this. I use thin clear plastic, the type you find on the front of packaging like a window that let's you look in at the item, I then use a compass cutter to cut 2 rings out of this and glue one ring to the underneath of the turret and the other around the turret hole in the hull, I do this after everything is painted and because they are sandwiched between the two it's not visible anyway, you have two nice smooth areas which the turret has a much easier time gliding across, HTH

Cheers, Lee.

[silversurfer1947]

I know I've said it before, but everyone is so helpful, particularly for a novice builder like me. I can't thank you all enough. I've not attempted the turret rotation yet, but with all the tips , I'm sure I shall find a satisfactory solution.

I have to say that I think that, by pushing myself outside of my comfort zone, I have learned more. I guess my Tamiya builds have spoilt me a little.

The recalcitrant axle assembly is nearly back together, when running in will resume. That way, at least I should find out any other bits I've messed up, before it takes its place on the battlefield!