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Keeping the Chassis Straight
chrisb760
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United Kingdom
Joined: January 05, 2015
KitMaker: 8 posts
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Posted: Thursday, October 12, 2017 - 06:33 AM GMT+7
Hi all I have built a couple of 1/35 military trucks. Trouble is that I always have a problem with the chassis and the difference and axles being straight. Any help would be appreciated
Thanks Chris
RobinNilsson
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Stockholm, Sweden
Joined: November 29, 2006
KitMaker: 2,336 posts
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Posted: Thursday, October 12, 2017 - 07:23 AM GMT+7
If the chassis sides have a straight top surface (nothing sticking up) I place them top down on flat and level surface, glue the cross members to one chassis side (frame rail ??).
Let this dry a little and then slide into place and glue the other chassis side.
I use small clamps to hold the chassis frame pressed against the flat surface.
This procedure requires that all cross members have been dry fitted before the gluing starts.
I usually use solvents to "glue" styrene and that allows me to dry fit everything to get it straight and then add solvents to the joints to make the bond.
If there are fittings/attachment points on top of the frame side the workaround is to place the frame rails on small, equal thickness, blocks.

Even if the chassis is straight it can happen that the suspension is crooked. Dry fitting and checking alignment usually prevents unpleasant surprises.

If the chassis is molded as a one part and this is crooked it can sometimes be twisted back into the correct shape. If the straightening fails the suspension will have to be adjusted to compensate.

Which truck models/kits have you built?
/ Robin
165thspc
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Kentucky, United States
Joined: April 13, 2011
KitMaker: 6,205 posts
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Posted: Thursday, October 12, 2017 - 11:39 AM GMT+7
As Robin said if you are lucky enough that either the top or bottom of the frame is flat. (Nothing sticking up.) Work on a fairly large flat surface, preferably a piece of glass, mirror or stone countertop. I usually start by attaching the first two, rear-most cross members to the side rails and weighing them down on the flat surface and letting it all dry thoroughly. (Overnight if possible.) Then I continue with the rest of the frame assembly, always returning it to the weighted flat surface.
petbat
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Queensland, Australia
Joined: August 06, 2005
KitMaker: 344 posts
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Posted: Thursday, October 12, 2017 - 03:09 PM GMT+7
Sometimes the unevenness is not the chassis, but the springs, etc supporting the axle housings or in the wheel rim to housing fitment, especially on vehicles with multiple parts with loose fit. If I want to make sure the wheels all touch flat, I make up a jig from Lego and have some thin post it pads handy. Usually you can build the Lego in a rough box shape or kind of Cross of Lorraine shape so the chassis rail bottom can fit in spaces between blocks leaving other fittings untouched, or left off until later. Then having cleaned and dry fit tested the rest, including the wheels, I assemble and adjust the suspension so the wheels all sits flush when the wheels are resting on the bench. I raise the height of the Lego by placing that assembly on the post-it note pads, with however many leaves removed to get the right height all way around. Leave it to dry and it should all be perfect.

Occasionally I will place a weight on top of the chassis before leaving it to dry.

(BTW. I turn the Lego upside down so the bumps are face down and rest the chassis on the flat bottom parts of the Lego).
GazzaS
#424
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Queensland, Australia
Joined: April 23, 2015
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Posted: Thursday, October 12, 2017 - 06:53 PM GMT+7

Quoted Text

Sometimes the unevenness is not the chassis, but the springs, etc supporting the axle housings or in the wheel rim to housing fitment, especially on vehicles with multiple parts with loose fit. If I want to make sure the wheels all touch flat, I make up a jig from Lego and have some thin post it pads handy. Usually you can build the Lego in a rough box shape or kind of Cross of Lorraine shape so the chassis rail bottom can fit in spaces between blocks leaving other fittings untouched, or left off until later. Then having cleaned and dry fit tested the rest, including the wheels, I assemble and adjust the suspension so the wheels all sits flush when the wheels are resting on the bench. I raise the height of the Lego by placing that assembly on the post-it note pads, with however many leaves removed to get the right height all way around. Leave it to dry and it should all be perfect.

Occasionally I will place a weight on top of the chassis before leaving it to dry.

(BTW. I turn the Lego upside down so the bumps are face down and rest the chassis on the flat bottom parts of the Lego).



...Any excuse to play with your LEGO's Peter?
petbat
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Queensland, Australia
Joined: August 06, 2005
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Posted: Thursday, October 12, 2017 - 08:40 PM GMT+7

Quoted Text



...Any excuse to play with your LEGO's Peter?




Absolutely, I even use it when I make moulds for casting



But be careful disparaging Lego my friend, or Ross will clout you at the next meeting.....
GazzaS
#424
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Queensland, Australia
Joined: April 23, 2015
KitMaker: 3,088 posts
Historicus Forma: 4 posts
Posted: Thursday, October 12, 2017 - 09:36 PM GMT+7

Quoted Text


Quoted Text



...Any excuse to play with your LEGO's Peter?




Absolutely, I even use it when I make moulds for casting



But be careful disparaging Lego my friend, or Ross will clout you at the next meeting.....



Actually, I'm rather impressed that you have found a use of it for molds as well as a construction jig.

I may have to borrow these ideas from you.

Gaz
chrisb760
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United Kingdom
Joined: January 05, 2015
KitMaker: 8 posts
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Posted: Thursday, October 12, 2017 - 11:18 PM GMT+7
M915,(1/35)
MAZ 537G,(1/35)
M983(1/35
M923A1 (1/35)
Faun SLT 50-3 (1/72)
On the table now KRAZ-260 (1/35)
In the cupboard MTVR Mk23 (1/35)
Next ZIL 131V
RobinNilsson
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Stockholm, Sweden
Joined: November 29, 2006
KitMaker: 2,336 posts
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Posted: Friday, October 13, 2017 - 08:06 AM GMT+7
Clever to use LEGO for jigs, must remember that ...
/ Robin
chrisb760
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United Kingdom
Joined: January 05, 2015
KitMaker: 8 posts
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Posted: Friday, October 13, 2017 - 07:16 PM GMT+7
Hello Robin I'm not quite understanding the bit about solvent being used for a dry fit
I have listed the trucks I have made in this thread
Thanks Chris
RobinNilsson
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Stockholm, Sweden
Joined: November 29, 2006
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Posted: Saturday, October 14, 2017 - 04:06 AM GMT+7
Solvent as glue:
There are some solvents (thinners if you like) which causes the polystyrene (or simply styrene) in plastic kits to go soft.
If this happens between two mating surfaces the plastic (styrene) will go soft (the binding between polymer chains is temporarily broken or loosened). After a short while the solvent evaporates and the polymer chains start to bind harder to each other again. This results in bonding across between the two parts.

Using tube glue: Smear glue on one surface, press the other surface into the glue, let dry and remove the excess glue.

Using liquid glue: Use a small brush to apply glue on one surface, press together, let dry.

Using solvent (or call it liquid glue without any solid content): Hold the parts together, apply a small amount of solvent to the joint, hold the parts together for a minute or so. Let it dry completely.

The advantage with using a solvent is that there is no residue outside the joint. It is possible to go directly from dry-fit to glued and finished without changing the position of the parts.
The dangers are spilled solvent, a kit can be wrecked in seconds. Another danger lies in the big advantage: the capillary action
https://en.wikipedia.org/wiki/Capillary_action
this will suck the solvent into the small gap between the two parts BUT it will also draw the solvent into the channels caused by your fingerprint. If you happen to hold a finger or thumb across the joint when applying the solvent the result will be a 3D-fingerprint on the surface of the plastic/kit.

The easiest and cheapest wat to get hold of a usable solvent is nail polish remover. If it has a content list you look for ethylic acetate. If it doesn't you can test it with a pice of styrene. A small drop on your thumb and press the thumb onto the styrene. Get a quick fingerprint? Yes = good stuff.
No or only a faint print = useless.
Nail polish removers are either with acetone or acetone free and you are looking for the acetone free stuff.

The method is easy to learn, easier than using tube glue.
/ Robin