Ludwig metal chassis assembly
09-22-2022, 07:47 AM
#1
Ludwig metal chassis assembly
So just to muddy the waters, I thought I'd start on a Ludwig Lowe kit. I specified metal chassis, thinking it would come pre-bent, you know, like a Tamiya. Well, no , it comes flat and milled. Minimal clean up on parts, mostly filing off small tabs, and the parts fit together very well. The question here is how to keep them together. I guess they could be TIG welded, if I was that good, or knew someone that good. They're a little too thin to drill, tap and screw together. I could come up with some angle brackets, I guess, but for the torsion bar brackets I don't think that would work. So adhesives... no CA, too brittle, and the ends of the machined parts aren't smooth enough to make that work. Regular epoxy.. I don't think so. So.. looking for suggestions as to what to use to hold it all together. It's going to be a large, fairly heavy vehicle so whatever I use has to be fairly robust. Pics...
09-22-2022, 10:17 AM
#4
I would look into having it welded by someone expert with a TIG or laser welder but that likely wouldn't be inexpensive. Alternately you could use your angle bracket idea but with rivets instead of screws; properly done
no one will ever see the rivets from the outside. It has the additional benefit of being able to changed if something turn out not to your liking. Experiment with rivets; I've found them very useful for things like this.
I've used both commercially available rivets (Hansen) and ersatz rivets made from large gauge aluminum electrical wire strands...
I built an Armortek M3 Lee and I actually riveted the entire upper hull together instead of the suggested way using scattered screws. It was strong enough that I could stand on it with no damage and I've had one too many good meals over the years...
Prior to that I made my 1/10 Hetzer upper hull from 2mm aluminum sheet riveted together using aluminum wire rivets and aluminum brackets inside. I like the electrical wire as it's very soft and easy to form and work.
Jerry
no one will ever see the rivets from the outside. It has the additional benefit of being able to changed if something turn out not to your liking. Experiment with rivets; I've found them very useful for things like this.
I've used both commercially available rivets (Hansen) and ersatz rivets made from large gauge aluminum electrical wire strands...
I built an Armortek M3 Lee and I actually riveted the entire upper hull together instead of the suggested way using scattered screws. It was strong enough that I could stand on it with no damage and I've had one too many good meals over the years...
Prior to that I made my 1/10 Hetzer upper hull from 2mm aluminum sheet riveted together using aluminum wire rivets and aluminum brackets inside. I like the electrical wire as it's very soft and easy to form and work.
Jerry
Last edited by Tanque; 09-22-2022 at 10:20 AM.
09-22-2022, 03:23 PM
#7
There's a few options for the hull
1) Take it to a welding shop and have them TIG tack weld it together from the inside (welds inside the hull vs on the outside). You want someone familiar with welding TIG Aluminum.
2) JB weld epoxy would probably hold pretty well, especially interlocking plates. Its damn strong stuff.
3) Make small aluminum angle plates and screws and screw it together - involves making angle parts and making more holes in that nice hull. This would be a lot of effort.
4) I've never tried the "aluminum soldering" sticks advertised on YTube and FB. These may work, but test on scrap first. The risk of warp would be high. I'd hate to ruin those hull plates by overheating them (which is why TIG is better).
I myself would go with 1 first, then perhaps 2 or 3 second. When I scratch build a hull I bolt it together with angle plates (3) above. But I also CNC drill those screw holes before cutting out the plate.
This hull looks like it was intended to be welded together.
What do the tracks and wheels look like? I've never ordered a Ludwig kit.
Bob
1) Take it to a welding shop and have them TIG tack weld it together from the inside (welds inside the hull vs on the outside). You want someone familiar with welding TIG Aluminum.
2) JB weld epoxy would probably hold pretty well, especially interlocking plates. Its damn strong stuff.
3) Make small aluminum angle plates and screws and screw it together - involves making angle parts and making more holes in that nice hull. This would be a lot of effort.
4) I've never tried the "aluminum soldering" sticks advertised on YTube and FB. These may work, but test on scrap first. The risk of warp would be high. I'd hate to ruin those hull plates by overheating them (which is why TIG is better).
I myself would go with 1 first, then perhaps 2 or 3 second. When I scratch build a hull I bolt it together with angle plates (3) above. But I also CNC drill those screw holes before cutting out the plate.
This hull looks like it was intended to be welded together.What do the tracks and wheels look like? I've never ordered a Ludwig kit.
Bob
Last edited by RC_BobM; 09-22-2022 at 03:28 PM.
09-22-2022, 05:19 PM
#8
The problem with trying to solder aluminum, especially thin aluminum you just can't tell when it's hot enough..
To get it hot enough for the solder sticks to flow you need to get the surface near melting point and with thin aluminum the surface is about all there is! By the time you realize it's going to melt it's already collapsed.
I have aluminum solder, had it for years. sometimes it's worked well, sometimes not. I still think riveting it is your best
and most cost effective way. We're talking flush rivets not like some world war 1 tank or an 1800's steam engine boiler with round head rivets.
Unless someone you know wants to TIG weld is for a six pack or you/they are really really good with Al solder it could come to grief quick. Last suggestion if you want to try solder: practice on soda cans; if you can make anything you want from soldering those together you're ready to stick your hull together; just scrape off the coatings on the cans first. Oh yes and at some point before you try it on your hull, try it on some alloy similar to what your hull is and as thick as your hull is because the performance of the solder varies based on those variables. And they're important dealing with thin sheet.
Regarding the strong adhesives like JB Weld, Stablit Express (Patex) - they're good but remember they're just
relying on adhesion; not bonding at a molecular level like a weld. I know adhesive bonds can be monstrously strong but
generally over a large surface area - not two thin sheets on an edge unless you use a giant glob of the stuff. I work
in the aircraft restoration volunteer group on the US Hornet museum in Alameda and I've gotten a real respect for
adhesive bonds: the F8 Crusader I helped restore had control surfaces made of a composite of thin aluminum sheet
sandwiched on balsa (yes balsa) wood: it was a patented thing called Metallite I recall and it was strong enough to deal with the stresses of a fighter aircraft and it was still tough as heck after 50+years. but that was an optimal use of metal to wood and metal to metal bonds and over a really large surface area. Not edge to edge.
I think your solution rests in a combination of all these methods. Just decide what you feel most comfortable with and go with it.
Jerry
To get it hot enough for the solder sticks to flow you need to get the surface near melting point and with thin aluminum the surface is about all there is! By the time you realize it's going to melt it's already collapsed.
I have aluminum solder, had it for years. sometimes it's worked well, sometimes not. I still think riveting it is your best
and most cost effective way. We're talking flush rivets not like some world war 1 tank or an 1800's steam engine boiler with round head rivets.
Unless someone you know wants to TIG weld is for a six pack or you/they are really really good with Al solder it could come to grief quick. Last suggestion if you want to try solder: practice on soda cans; if you can make anything you want from soldering those together you're ready to stick your hull together; just scrape off the coatings on the cans first. Oh yes and at some point before you try it on your hull, try it on some alloy similar to what your hull is and as thick as your hull is because the performance of the solder varies based on those variables. And they're important dealing with thin sheet.
Regarding the strong adhesives like JB Weld, Stablit Express (Patex) - they're good but remember they're just
relying on adhesion; not bonding at a molecular level like a weld. I know adhesive bonds can be monstrously strong but
generally over a large surface area - not two thin sheets on an edge unless you use a giant glob of the stuff. I work
in the aircraft restoration volunteer group on the US Hornet museum in Alameda and I've gotten a real respect for
adhesive bonds: the F8 Crusader I helped restore had control surfaces made of a composite of thin aluminum sheet
sandwiched on balsa (yes balsa) wood: it was a patented thing called Metallite I recall and it was strong enough to deal with the stresses of a fighter aircraft and it was still tough as heck after 50+years. but that was an optimal use of metal to wood and metal to metal bonds and over a really large surface area. Not edge to edge.
I think your solution rests in a combination of all these methods. Just decide what you feel most comfortable with and go with it.
Jerry
Last edited by Tanque; 09-22-2022 at 05:23 PM.
09-23-2022, 01:45 AM
#9
Just out of curiosity, does Ludwig have any suggestions as to how to join the plates? I imagine he's built at least one or two so it might be worth an email to see what he says.
09-23-2022, 10:23 AM
#10
That looks to 1/8th inch plate, if so you could bolt them together with angle aluminum stock and the thickness would allow for countersunk bevel head bolts such that a bit of Bondo over the bolt head and light sanding would make a smooth outside surface. This is the method I used making my all aluminum Maus with aluminum sheet stock.
If you have a good drill press with stops, makes this method not so bad.
If you have a good drill press with stops, makes this method not so bad.
09-23-2022, 10:24 AM
#11
He suggests metal glue, so I think he means some form of epoxy.
I'm a little familiar with structural metal bonding, There's prorablly a solution out there from Hysol but I'll bet it's expensive. Very expensive.
Tracks/running gear are taken from a donor Tamiya King Tiger tank. Tracks need to be extended somewhat.
I'm a little familiar with structural metal bonding, There's prorablly a solution out there from Hysol but I'll bet it's expensive. Very expensive.
Tracks/running gear are taken from a donor Tamiya King Tiger tank. Tracks need to be extended somewhat.
09-23-2022, 11:43 AM
#12
That looks to 1/8th inch plate, if so you could bolt them together with angle aluminum stock and the thickness would allow for countersunk bevel head bolts such that a bit of Bondo over the bolt head and light sanding would make a smooth outside surface. This is the method I used making my all aluminum Maus with aluminum sheet stock.
If you have a good drill press with stops, makes this method not so bad.
If you have a good drill press with stops, makes this method not so bad.
The angle stock is a great suggestion, but won't work along the longest seam I need to join, as the bearings for the swing arms ride right at the level of the lower plate. I'd have to do multiple, small pieces, and might as well just use angle brackets at that point. But it would be a good excuse to get a drill press
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09-24-2022, 03:56 PM
#15
Well, both my solutions showed up today. Based on a few minutes practice I decided to try and use the AL brazing rod. I got the Bernzomatic brand, if anyone is curious. Only real trick was to not leave the MAPP gas torch in one place too long, as it would do "things" to the aluminum. (found out on a practice piece). The real work was the filing to get everything to fit together tightly.. although this stuff will bridge pretty big gaps.. not too shabby for my first time, if I do say so myself...
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09-24-2022, 03:59 PM
#16
I am going to regret not filing out the holes on the torsion bar anchors before I brazed them in place. they're just a little too small for the ends of the swing arms. And the steely eyed might note that they stick out a little from the rear of the lower hull, I placed them with swingarms in the bearings to ensure that they were straight, and they wound up a little to the rear.
09-26-2022, 06:51 AM
#17
Just a note on the brazing process.. I started with my propane torch, but switched over to the MAPP gas torch. VERY IMPORTANT to not leave the head in one place too long.. it will soften and melt the AL. But it's manageable... and if you keep checking the joing with the brazing rod for temp, thyere's no way you'll get that hot.
I had to re-do a couple joints, I did some pulling and twisting and snapped a couple. I take that to mean that I didn't clean well enough prior to brazing, so before making more joints for reinforcement I made sure to sand thoroughly and clean with alcohol. Live and learn, I guess. Another word of warning, if you're going to braze, remove any and all Tamiya cast parts first. They have a fairly low melting temperature. DAMHIK...
I also managed to warp one side of the hull while brazing.. not terrible, but still. I don't think I need to fix it, it's not effecting any running gear or such, just the inner splash guard.
I got around to installing the tamiya swingarm bearings. Since the Lowe hull sides are so much thicker than the KT's, the bearings need to be modified by sanding the inside surface somewhat to allow the swingarms to go all the way in. I considered modifying the swingarms instead, but working the bearings was a whole lot easier, and I could be more consistent. The very rear bearing on the L/H side of the hull needs to be modified even more, as there is only one screw hole to retain it. Modifying the bearings raises another problem, now the swingarms rub on the hull, and teh screws holding the bearings interfere with the swingarms. Time to source some countersunk screws, I guess. I did comment to Christian that milling recesses on the back side of the side plates to fit those bearings might be a better solution. Next steps are to drill the gearbox mount plate to fit the impact gearboxes I have, and wait patiently for my missing idler mount to show up. Then we'll get it on its feet.
Nice warp, eh?
That's a big ass turret.....
I had to re-do a couple joints, I did some pulling and twisting and snapped a couple. I take that to mean that I didn't clean well enough prior to brazing, so before making more joints for reinforcement I made sure to sand thoroughly and clean with alcohol. Live and learn, I guess. Another word of warning, if you're going to braze, remove any and all Tamiya cast parts first. They have a fairly low melting temperature. DAMHIK...
I also managed to warp one side of the hull while brazing.. not terrible, but still. I don't think I need to fix it, it's not effecting any running gear or such, just the inner splash guard.
I got around to installing the tamiya swingarm bearings. Since the Lowe hull sides are so much thicker than the KT's, the bearings need to be modified by sanding the inside surface somewhat to allow the swingarms to go all the way in. I considered modifying the swingarms instead, but working the bearings was a whole lot easier, and I could be more consistent. The very rear bearing on the L/H side of the hull needs to be modified even more, as there is only one screw hole to retain it. Modifying the bearings raises another problem, now the swingarms rub on the hull, and teh screws holding the bearings interfere with the swingarms. Time to source some countersunk screws, I guess. I did comment to Christian that milling recesses on the back side of the side plates to fit those bearings might be a better solution. Next steps are to drill the gearbox mount plate to fit the impact gearboxes I have, and wait patiently for my missing idler mount to show up. Then we'll get it on its feet.
Nice warp, eh?
That's a big ass turret.....
09-26-2022, 12:04 PM
#22
09-30-2022, 06:37 PM
#23
Countersunk screws showed up.. the day after I ordered them. RTL fasteners to the rescue! Helps that they're just down the road in Chesapeake, too. So, a couple fun hours with a drill bit, and some further drill bitting to free up the swingarms, and we have:
So, instead of mounting gearboxes and such, let's glue some plastic together. The rear of the sides of the hull are located by tabs on the rear plate. For some reason or other, though, when I put the glacis plate on, the sides didn't quite reach it... also, I wasn't quite clear on how to remove the upper hull with the rear trapped by tabs. So, I cut the plastic behind the tabs, and positioned the side plates to touch the glacis plate. There were some further small issues with the inside plates (from the lower hull to the side plates), but I soldiered on. With German drinking songs blasting on the stereo, no less. I have plenty of plastic sheet, and lots of bondo. I can hide things. But I must say, I feel like I missed something somewhere...
If I pulled the side plates out to the end of the Glacis plate, then the inside plates didn't fit at all... so, I let the fit be determined by the inside plates...
I'm not sure why that came up short, I lined up the "break" with the side plates.
Some heavy duty trimming of the Glacis plate seems to be in order...
But there was nothing i could do here... the width is controlled by the metal rear plate, and I need the inside plates to sit on the hull... so, filler pieces! Well, reinforcing pieces for now, filler pieces later. OR maybee bondo. Depends on how lazy I feel.
Same on this side.....
So, instead of mounting gearboxes and such, let's glue some plastic together. The rear of the sides of the hull are located by tabs on the rear plate. For some reason or other, though, when I put the glacis plate on, the sides didn't quite reach it... also, I wasn't quite clear on how to remove the upper hull with the rear trapped by tabs. So, I cut the plastic behind the tabs, and positioned the side plates to touch the glacis plate. There were some further small issues with the inside plates (from the lower hull to the side plates), but I soldiered on. With German drinking songs blasting on the stereo, no less. I have plenty of plastic sheet, and lots of bondo. I can hide things. But I must say, I feel like I missed something somewhere...
If I pulled the side plates out to the end of the Glacis plate, then the inside plates didn't fit at all... so, I let the fit be determined by the inside plates...
I'm not sure why that came up short, I lined up the "break" with the side plates.
Some heavy duty trimming of the Glacis plate seems to be in order...
But there was nothing i could do here... the width is controlled by the metal rear plate, and I need the inside plates to sit on the hull... so, filler pieces! Well, reinforcing pieces for now, filler pieces later. OR maybee bondo. Depends on how lazy I feel.
Same on this side.....
10-09-2022, 05:03 PM
#25
I also started harvesting bits and pieces from a donor K-T upper hull and turret...
First bit mounted.. more to come. I will also get the fans, etc off the rear deck...
Gearboxes mounted. They're Impact, actually for a panther but they're lowe (see what I did there) ratio, so they should work, and provide a more realistic speed.
But that raises a couple issues. First, the gearbox mounting plate has to be attached to the 2 rails on the lower hull. Can't braze, so they're going to have to be glued. Or... my prefered method would be to bolt them, using standoffs. But... there are openings on the lower hull, that don't allow me to drill where I need to drill. Also, the torsion bars run through there, not sure if the're going to get in the way or not... Anyway... I'd be glad to hear suggestions if anyone ahs any...
First bit mounted.. more to come. I will also get the fans, etc off the rear deck...
Gearboxes mounted. They're Impact, actually for a panther but they're lowe (see what I did there) ratio, so they should work, and provide a more realistic speed.
But that raises a couple issues. First, the gearbox mounting plate has to be attached to the 2 rails on the lower hull. Can't braze, so they're going to have to be glued. Or... my prefered method would be to bolt them, using standoffs. But... there are openings on the lower hull, that don't allow me to drill where I need to drill. Also, the torsion bars run through there, not sure if the're going to get in the way or not... Anyway... I'd be glad to hear suggestions if anyone ahs any...
