Test Driving the TDR 427 Roadster

[sydeem]

There have been few, if any, times I have felt privileged in my 80 years but this is one of them. Just as I was trying to convince the wife some of our social security should be budgeted for a new TDR model Don asked if I might be interested in building and debugging one of the first prototype 427 roadster kits. As I answered YES 2 microseconds later I could not believe my luck. I have built just about every kit TDR produces except the Allison (no way would the wife stand for that expenditure) and I think this kit will be THE bell ringer. As you will see there is a new process that I hope Tim might discuss as we go along.

What a difference with the material. The parts seem to have a much higher resolution finish. Round and slanted surfaces are smooth. Through holes are sharp and clean. The material on these first parts seems much harder (stiffer?) than the other kits. Still need to do sanding on parts that represent steel rod or tubing but I bet there will be no need for sanding cast parts like engine blocks. One really great thing about this new material is that dropping the parts is no longer a catastrophe. I have a habit of dropping parts and I shattered some of the parts on the Deuce IFS/IRS and did so many on the first Offy I had to buy two kits. I have inadvertently dropped a few of these parts already from chest height to a tile floor with no problem. (Don’t start tossing parts around at random but you don’t have to have a heart attack as a part slips from your hand.)

I just received initial parts for the wheel suspension assemblies. These are the front spindle parts including shock end pieces. There is a hole the FULL length of the spindle that is about 0.047” diameter and is a slip fit for a 00-90 bolt. (Can you imagine that!, printing an inside hole that diameter with no obstruction.) Right now I'm torn between possibly using two ½” long bolts inserted into the spindle from each end to hold the assembly together or possibly buying some 0-90 rod to run the full length of the spindle. We will see as the model progresses. The rod with nuts would capture the A arms best but the hex head cap screws (bolts) may finish better and the ½” length may have enough friction to hold the parts. We will see when we get that far along.

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These are the rear wheel mount parts including shock end pieces.

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This is the radiator frame.

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[RonOC]

I'll be following this with great interest!

I also looked at the other photos.

Ron

[Don Garrett]

That's what this thread is all about Ron.
Here at TDR we feel that by showing all the parts as they go into production (they are numerous), the construction of the prototype, hearing your feedback -suggestions, building tips and solving build problems along the way will result in a production model that will give you a lot of bang for your buck.

In other words, at the conclusion of this build, you will know exactly what you are getting for your hard earned money and there will be no feelings of disappointment when the packages arrive and are opened.
You'll have all the info provided here to refer to during your assembly. This thread (at the moment) is being posted on SMC and MCM....you guys are seeing the final production model as it's built......first!

[hot ford coupe]

TDR is making model car history. You'd never see RM doing something like this.

[Don Garrett]

TDR is making model car history. You'd never see RM doing something like this.

Ya think?

[3.Star]

Keep on going Syd.

I am watching your progress closely, and already sat on some Santa Clause's laps in a Mall to tell him about my Christmas wish to have the TDR Roadster.




Cheers

Michael

[sydeem]

These parts feel very solid to me but Tim suggests applying some CA glue to the surface of the parts to add just a little bit more stiffness to the parts for long-term sag prevention. I have tried the process and discovered a few pitfalls.

1. Careful or you might be going to bed with an A arm glued to your finger.

2. The CA glue quickly wicks through the parts farther than one would think. I tried the old idea of toothpicks stuck in styrene to hold and dry the parts. You can do this if you only coat ½ of the part at a time and leave plenty of space between toothpick and where glue touches the part. Still I had a few toothpicks glued in place even doing this.

3. I had to cut off those toothpicks and drill out the residue. The wood is much softer than the RP material so careful use of a #62 drill in a pin vise will generate a pilot hole and then you can drill to the original hole size. I am pretty sure the RP material will push you into whatever wood is left because it is much stiffer than the wood. Just don’t get in a hurry and angle the drill.

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Edit: Suggestions by Tim for a better method of using CA on the parts:

1) With the toothpick method, do half the part and let it dry on the toothpick. Just make sure the part is hanging down so maybe the glue will wick away from the toothpick

2) Better yet (no toothpick) lay the part down on some wax paper. Just make sure no glue is puddeling where it touches the paper and you can also tilt the part, lean it up against something, to minimize the contact patch with the wax paper

3) Use a CA kicker spray. The CA will dry instantly if you use this. You will just have to wash the part in some mild detergent to remove the kicker.

[Rick]

Syd

Try hanging the parts on a piece of thin thread. While hanging, hold the part with tweezers and paint on the CA with a brush. If you use quick dry CA and keep moving the parts along the thread, you won't have any problems with the thread sticking inside the holes.

[Herman]

Are these 3D printed in powder, with an inkjet system to spray the glue on the places where glue should be?

If so, indeed these can be utterly brittle. The company I visited for some 3D print work, impregnated all products with epoxy resin as standard.

This is best done directly after printing, with a large bunch of parts, as you will need to mix a large amount of epoxy , preferably of a slow, low viscosity type. Then 1 by 1 dip the parts in the epoxy for a couple of seconds, transfer them to a stick or hanger, and cure them with heat.
Hanging them in only a couple of seconds helps keeping the surface "dry" so the part will not stick (too much) to the pin or hanger. The epoxy gets sucked into the part during the transfer from epoxy bath to hanger.

[Daytonatim]

Are these 3D printed in powder, with an inkjet system to spray the glue on the places where glue should be?

No these parts are manufactured a whole different way.

The parts that Syd has been showing you are made of a material called Alumide. What it is is a mixture of nylon and aluminum powder. The printer spreads out a thin layer of powder, about .005" thick. Then a laser actualy melts and fuses the nylon powder together.

The aluminum is added to increase the stiffness of the parts. That is why we use them on all the suspension parts, because the added stiffness will be benificial in the highly stressed parts that support the weight of the entire model. I have never broken one of the alumide parts, though I have bent and pushed on them considerably. judging from their stiffness I would gues that they would break but it would take considerable flexing to make it break. I would guess that is very similar to your good ole styrene plastic in this aspect.

Now the only reason we applying the CA to the high stress parts is just to add a little bit extra insurance against parts sagging over a very long period of time. We mine as well fill these pours up with something that will add more to the stiffness of the part than just air.

Syd will actually be receiving the rest of his parts very very soon. They are made of just the nylon powder. We use the pure nylon parts in the areas that are not stressed as much. Now these parts are very very tough. Our manufacturer has a video on their website showing a creditcard made of this stuff being folded in half and worked back and forth many times without the part breaking.

Now, because the parts are made of a dry powder, they are very pourous. This has the benefit of making for a very light part but the pourous surface has to be addressed to achieve the final desired surface finish. We will go into great detail of the finishing process thoughout this thread.



Well, I hope this clears up some of the questions about this new material.