Jump to content
Model Cars Magazine Forum

Chassis Building


iBorg
 Share

Recommended Posts

I'm getting ready to do a tube chassis using Evergreen plastic. In the past I've used Ambroid glue but that's no longer available. I'm debating between Plastistruct Plastic Weld, CA and Tamiya Thin. Any recommendations? I'm looking for quick dry time and strength. Of course, I could also solder it.

 

Also at one point there was a pretty good pdf on how to construct a pro mod or pro stock chassis. I thought I saved it but it seems to have disappeared. If you've got that, could you send it to me?

Thanks,

Mike

Edited by iBorg
Link to comment
Share on other sites

Hey, Mike. I have Flex-I-File cement, now. I used Ambroid, as well. I like the Flex-I-File cement, just fine. When this bottle's gone, I will be using Weld On. I ordered mine online, but, I have heard Home Depot carries it. I've used the Plastruct cement, too. It works well, too. I am going to guess that many of these cements have the same solvents. Not sure this is any help!grin

Link to comment
Share on other sites

The two most common bases for liquid "plastic cement" are MEK (methyl ethyl ketone), and methylene chloride (also known as dichloromethane).

Plastruct "Plastic Weld" is MEK. Plastruct "Bondene" is methylene chloride (as is Flex-I-File's "Plasti-I-Weld and Scalecoat "Probond".

In my experience, the MEK products generally seem to penetrate deeper, dry slower, but make a stronger bond. The methylene chloride products wick between parts better, dry faster, but may not be as strong ultimately.

There's no secret trick to building any kind of chassis. In general, start with the main rails pinned to a suitable substrate to keep them parallel and level. Build the cowl or firewall support structure and main rollover hoops first. Progress from there, keeping things symmetrical by fitting one chassis tube very precisely (it helps the bond-strength to "fishmouth" tube ends where necessary with a small round file), and then making an exact copy of it for the opposite side before you bond the first one in. It's tedious and fiddly in the beginning, but you'll pick up a lot of speed as you get used to doing it.

Permanent bends can sometimes be formed by using nothing but your fingers, but work slowly when forming so you don't cause cracks. Some plastic rod stock tends to spring back and won't hold a shape indefinitely. If you can get it glued in position before it springs back, great. If that's too hard, forming your bends around something like an X-Acto handle, wooden dowel, or anything with the correct radius, and then dipping it in boiling water for a few seconds will "temper" it, and it will hold its shape forever after.

Nothing looks worse than wonky chassis tubes that aren't parallel, or gaps at joints, or joints that don't line up.

"Welded" joints that don't look perfect can have "weld fillets" made with a small bead of CA gel. It also reinforces the joint. I use Loctite Ultra-Gel. The tip doesn't clog, and the applicator is just right. It DOES take a while to dry however, so build your chassis up first, and at the end, go back and finish your "welds" and set it all aside to dry overnight. When it's dry, you can file and sand it to perfect shape.

                                     image.jpeg.08b75f13569371fd5bbc228aba6cbcf5.jpeg

Edited by Ace-Garageguy
Link to comment
Share on other sites

Thanks for the words of wisdom. I've done a couple of dragsters, an altered and a Piranha. This is a different design than I'm used to. I really am concerned with the glue selection. I'll get some more Plasti Weld.

Link to comment
Share on other sites

I'm highly allergic to superglue so I've had to become knowledgeable about alternatives, In the realm of styrene to styrene bonding my preferred weapons of choice are Testors "Red Tube", Testors Liquid Cement, Tamiya Thin liquid cement, and MEK. As a cheapskate S.O.B. I was attracted to MEK because it can be bought for pennies an ounce in the pint cans at most hardware stores. It's so cheap that you can Do The Right Thing by throwing it out the moment it gets cloudy (and much weaker) from dissolved plastic residue. It penetrates very well, but is slower to bond than Tamiya Thin or Testors Liquid, neither of which penetrate as well or dissolve the plastic as aggressively. Also MEK will damage surrounding surfaces more than the other two liquid cements. Testors liquid is good where you need some initial "tack" to locate things. Tamiya Thin is a little less tacky, because it's thinner, and MEK has almost no initial tack, so it generally requires an initial softening application to both surfaces and then a second (or more) pass for a dissolving bond.. For really near-instantaneous tack Testors Red Tube is my choice, but it's thick and doesn't offer as clean a joint unless you are very sparing with the amount you apply. . But Red Tube is great where the glue joint is totally hidden, like flat surfaces. Where you can clean up the surfaces afterward I recommend using a more tacky glue for the initial locating bond and then following up with several wicking passes of MEK for a truly permanent "welded" bond.

Edit: As an afterthought, but useful if you're using liquid cements, I recommend buying Tamiya Thin and saving the bottle when it's empty for your other liquid cements. The low, squat square bottle won;t tip over and the applicator brush seems to resist even the harshest solvent glues. My Tamiya bottles have lasted many years.

Edited by Bernard Kron
Link to comment
Share on other sites

I built a "semi" pro-mod chassis for my Ford Escort using styrene rod rather than tubing - tubing seems to crack too easily.  I also use MEK as a solvent.  One word of CAUTION is to allow plenty of ventilation around your work area, MEK is some pretty nasty stuff and can cause 'drain bamage'.  I used the Revell '55 Chevy Scott Carpenter knock-off as a pattern, just reduced the measurements to fit within the body of the Escort.  Here are a couple of photos:

 

Escort Pro-Stock 016.JPG

Escort Pro-Stock 011.JPG

Link to comment
Share on other sites

Hi!

In my case, I use Testor's glue (the black plastic bottle), very sparingly, but applied to both side of the fishmout joint BEFORE joining them (90 seconds). After it dried for 24-36 hours, I "paint" a VERY light coat of straight MEK, to "blend" the joint even more, giving a usually solid and smooth assembly, that will withstand endless adjustemnts and mounting-dismounting common in extensive builts. 

To fight "spring back" of bended tubes, I insert a strand of copper electrical wire at the estimated location of any sharp bend. Not only does it remain in your favored shape, but it also helps avoid caving or kinking of the tube surface during sharp bends. 

Good luck with your project!

CT

 

DSCF3726.JPG

Link to comment
Share on other sites

  • 2 weeks later...

It is a shame we can no longer acquire Ambroid's Pro Weld liquid cement. However, Micro-Mark sells a new product, unbelievably called 'Same Stuff' and claims to be the same formula as Pro Weld. I have purchased and used this new Same Stuff cement and it is just like Pro Weld.

Link to comment
Share on other sites

  • 1 month later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...