Test Driving the TDR 427 Roadster

[LR3]

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 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.

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

This is the radiator frame.

[GrandpaMcGurk]

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 MCM and SMC....you guys are seeing the final production model as it's built......first!

[LR3]

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.

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

1) With the toothpic 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.

Edited December 11, 2010 by LR3

[arick]

Syd

What I do is hang the RP parts on a piece of thread. Use a pair of tweezers to hold the part steady while applying the CA glue with a brush. If you use the quick dry CA and keep moving the parts on the thread you'll have no problems with the thread sticking to the holes.

[DaytonaTim]

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.

--------------------------------------------------------------------------------

[LR3]

New Parts - Different Material

Another box of parts showed up today and I can see why this kit could well be bought in sub kits. The chassis and suspension consists of enough parts for three or four stand alone kits and we still have the engine, interior, body, wheels, etc., etc.

The chassis is a work of art. Thankfully we don't have to put it together. I had problems trying to construct motor mounts for the Hemi 426 blocks when mounting them to the Deuce chassis. Note they are built in here! All the little holes for mounting hardware are in place and clean as a whistle.

The material feels as strong as Tim mentions but I am not about to test its overall tensile strength. I am very heavy handed and it is nice to know I will not have any problems with long thin parts.

I have not identified all the parts that have arrived so far but they are an initial mix of chassis, steering, motor and interior. Can't wait to start grouping them and begin the finishing process. I have been working on two finishing methods for the original stiff suspension parts and that should be covered next.

[Foxer]

I'm all giggly just looking at those parts with all their bumps, holes and intricacy!

[LR3]

Strengthen the Frame

To ensure the frame does not deform over a long period of time, Tim has suggested we insert a ¼" brass tube in the hollow frame rails. A ¼" brass tube from K & S would work great. The tube needs to span the distance from the rear most back suspension mount to the front most front suspension mount. It will be captured by the radiator frame but should be epoxied in place.

Tim suggests these steps:

1) Test fit the tube in the chassis (no epoxy).



2) Determine the length to cut the tube, remove and cut it.



3) Test fit it back in the frame, (no epoxy)



4) Test fit the radiator frame to the frame tubes with brass tubes in place.



5) If all looks good, disassemble and remove brass tubes. 



6) Mix up some 30 or 60 min epoxy and apply to outside of the brass tube. 



7) Insert the brass tubing down into the frame tube.



8) Push it all the way in with a scrap piece of tubing. 



9) With a tooth pick, wad of paper towel, or similar remove any residual epoxy that is in the mouth of the frame tube.



10) Stand the frame up so that the ends of the frame tubes remain open and free from epoxy as it sets. The radiator support mounts in these openings and they must remain clear.
 



Edited December 11, 2010 by LR3

[LR3]

Finishing the new TDR material requires a different technique than before. The Aluminized (Grey) parts are very hard and not easily sanded down as the original RP material. The Nylon (white) parts are tough to sand and can leave a peach fuzz finish. Tim has found "It does "peach fuzz" if you sand it with the "grain", meaning with the layer lines. He has had the best luck sanding against "the grain" with emery boards. It seemed to smooth right down. He also used an X-acto knife to "shave" the few heavy grain lines. When he says shave, he means tilt the top of the knife IN the direction of movement. It seems to take the "peach fuzz" off."

Tim has suggested a new technique below. It really saves finish time. I tried it and I also tried just using primer then sanding the parts. Tim's suggested method is faster than multiple layers of primer and sanding. One cannot achieve a really smooth surface with one primer coat. I was happy in some cases with three layers of primer and light sanding but in some cases I wound up with more layers of primer and light sanding. I think the difference was probably the thickness of the primer coat in each step. When dealing with the Nylon parts, like Tim, I also found that scraping (like spreading butter) the surface with an X-acto or scalpel smoothed the primed surface best.

What we are doing is filling the void pits while just filing or sanding off the peaks to reduce finish time. We only need to remove the layer lines and work the surface, with a file for the Alumide and a sanding stick for the Nylon parts, to remove any loose stuff or any "peach fuzz"

The material on the left in the picture is called Ceramcoat and comes in a wide mouth jar as shown or in smaller 4, 6 and 8 oz. bottles. I used the Ceramcoat on half the parts and the primer shown on the right on the other half. Tim's method is much faster but you do have to watch for drips. I fought his technique at first but if you do a few parts at a time and pay attention to drips or build up it works out to be the best procedure.

Here is the process Tim found suited him best in his own words:

1) Do a quick light sanding/filing of the parts. (I like using my micro files) Also, look for any loose plastic residue in some of the small holes and crevices and remove it.

2) Pass a small, correctly sized, brass rod through a hole in the part. This is to give you something to hold the part by and to suspend the part during the curing process. I do not recommend using styrene rods, as they are not very stiff and are likely to sag and bend while the parts are drying. Brass is the best choice.

3) Submerge the part into a bath of something called "Delta Ceramcoat" All-Purpose Sealer. I found it in the paint section of my local Michael's craft store. This stuff is used to seal the porous surface of ceramic crafts, so it could be in the ceramic section too. It appears to be an acrylic substance that has a milky white color but dries clear. It comes in an 8 oz bottle. Submerge the part and let it soak up the liquid for about 30 seconds or so.

4) Remove the part from the bath, shake off the excess, then using a Q-tip just dab off any excess that is collecting in the crevices. Check back occasionally for drips or build up in any crevasses.

5) Wait about 45 minutes and then lightly wet sand.

6) Repeat steps 3 and 4 again.

7) Then hang the part and let it dry for 24 hours.

8) Using 220 grit wet/dry sandpaper WET sand the parts to remove any excess Ceramcoat that you find. I have not found the excess Ceramcoat to be a major problem as it shrinks quite a bit as it dries and does not result in any nasty hanging goobers or anything. If you find some spots that have excess buildup, just wet sand it away.

NOTE: I do NOT recommend dry sanding this coating material. It seems to ball up and create goobers that need to be removed.

9) Shoot with a standard high build primer. Nothing thick, just a good wet coat of primer, and let it dry.

10) Sand and paint as normal.

That is it. No major sanding. Just saturate the part with a sealer, wet sand, and paint.

I do not know exactly what this sealer is made from. It appears to be an acrylic. It has no odor and it cleans up in soap and water. So it is really hobby room friendly.

I would recommend building some kind of wooden rack that you can stick the brass rods into while the parts dry.

[LR3]

Probably the most complicated part to finish will be the frame. I just used primer coats sanding after each coat but Tim used the Ceramcaot technique and had a much easier time of it. I brush painted the areas with Cearamcoat I could not handily reach with a sanding stick. Cearamcoat is definitely the way to go particularly later with the cowl hoop and the radiator support frame.

Note: Do not use toothpicks to hang parts treated with Ceramcoat as they will be glued in by the Ceramcoat and break off when trying to remove the part. Also it is not effective to use Ceramcoat after trying primer because primer seals the pores and the Ceramcoat then just adds a layer of material over all. The Ceramcoat seems to pull into the pores of the RP as it dries and maybe surface tension smoothes it out. Remove almost all the Ceramcoat from the surface with a Q-tip or paintbrush, including the stuff that “puddles†in the grooves and fillet areas. Hang the parts to dry when there is virtually no Ceramcoat on the surface of the part.

[LR3]

Below is a picture, provided by Tim, of the frame assembly showing styrene rods to be added by the modeler.

Here is an excellent reference drawing Tim has provided for checking the frame part positioning and identifying the dimensions of the styrene rods we need to obtain.

This is a picture of the frame kit parts: radiator frame, front outriggers, pedal assembly, cowl bow and rear outriggers.

The parts are mostly slip fit as the printer follows the CAD drawing so the outriggers require any primer and/or paint to be removed for fitting. I chose to finish paint the individual parts (pedal assembly will be painted before attaching) before assembly. If too much of the frame is assembled before painting I believe one will find it difficult to paint all the nooks and crannies without over painting or missing some areas. Also the pedal assembly requires other colors than black and I think it needs to be incorporated during assembly as it is inserted between the front outrigger and cowl bow. I am not sure one could pull the bow and outrigger far enough apart for insertion otherwise.

Seems like the key part to initially set up is the cowl bow. Some kind of square is essential to insure the cowl bow is vertical to the frame. Once that is established it sets the attitude of the front outrigger and pedal assembly. The height at the front outrigger end point can be checked against Tim's Mechanical drawing. The other front outrigger can then be matched for position. The rear outriggers are to be horizontal and if the mating surfaces are clean they will naturally be horizontal. As everything is a slip fit it is easy to mate all the parts to evaluate the assembly process before actually gluing the individual pieces. Slow (thick) CA glue or epoxy is the best adhesive.

[LR3]

The shock assembly consists of two end pieces and a spring. You need to supply your own 1/8" aluminum tube for connecting the ends. The 5/16" X 3.75" spring may be supplied as part of a hardware kit. It has been heated to cherry red and let to air cool. This removes the hardness from the steel to allow one to cut it and stretch/compress it to the size necessary for the 4 shocks. The approximate length for each spring is as follows. The front springs should be 3/4" long and the rear springs should be 1" long. Cut the springs to these lengths and then stretch or compress the springs for the final fit. It is recommended to cut these springs with a Dremel tool and a cutoff wheel. This will result in minimum distortion to the ends of the springs. Cutting them off with snips it is almost sure to bend the springs at the cuts.

If more travel for the shock is desired the spring can be expanded as shown. The steel is very stiff so for as much expansion as I have shown on the left, one almost has to pull the spring apart one loop at a time with small needle nose pliers. Spring on the right is as provided.

[Harry P.]

Very impressive. Thanks for the great photos and commentary.

[LR3]

This really is a multimedia model. There will be aluminum panels, RP pieces, a fiberglass body and resin parts for detail. The Madd Fabricator sent a batch of resin parts consisting of wheels front and back, brake rotors (bottom line of parts), battery, two fan motors (top two white parts) and the complete rear end assembly parts (top right). The resin detail is sharp and clean, other than cleaning a little casting flash from the wheel openings these parts are ready go.

[LR3]

The front spindle assembly consists of the spindle, rotor, caliper and steering bracket. There is a subtle difference in the size of the rotors. The front spindle uses the larger rotor. There is a subtle difference in the steering brackets. There is a left and right. The calipers and rotors can be glued to the spindles but I chose to use two 1mm steel bolts for attaching the calipers. The nylon RP is strong enough to hold threads at least once if the holes are cleaned up with a slightly undersized drill. For detail overkill I used a copper wire and two 1mm steel nuts to simulate a cross over for the caliper pistons. I also used 1mm bolts to attach the steering bracket.

The rear spindle assembly consists of the spindle, rotor and caliper. Note the front spindles have the calipers mounted to the inside of the spindle bracket while the back spindles have the calipers mounted to the outside of the spindle bracket.

[LR3]

Plans – who needs plans?

TDR has started a complete and detailed set of instructions for the project and I have found it is important to follow the sequence or you will find real interference problems when trying to get to certain bolt or assembly areas. This is a "shake down" build as TDR is looking for all the pit falls that a modeler may fall into in an effort to steer them clear of these problems such as attaching the radiator mount before installing the front spindle assemblies. I am one of the designated pioneers and certainly not as experienced as many on this site. Any suggestions or comments from other members would certainly be appreciated by TDR.

The nice thing about a bolt together mechanical build is the ability to regroup so even though I had forged ahead building out of sequence I can regroup by unbolting areas where I went astray. I just can't unglue the radiator frame from the chassis frame or the pedal assembly. The radiator frame makes it difficult to get at the front spindle assembly mounting bolts but the attaching the pedal assembly will create a problem later with the aluminum pedal box.

I had used 1 mm bolts (Scale ¼" for 1:1) to attach all the brake calipers and the two steering brackets. Tim pointed out the proper scale bolt should have been 00-90 (Scale 3/8" for 1:1) as pictured following the three plans. Disassembly and rebuild was no problem.

Here are plan sheets 1 through 3.

[MrObsessive]

I'm just BLOWN AWAY by this thread!

OUTSTANDING castings and great informative step-by-step so far!

[LR3]

The Rack and Pinion steering assembly and installation is Step 4. The parts consist of the rack and pinion mechanism, the outer rod ends and the steering arms plus modeler supplied 0.1" styrene rod cut to the length required to attach the rod ends. You can see the disadvantage of jumping ahead of the instructions when accessing the mounting bolts behind the radiator frame. The bolts will be a press fit as there is no room for a wrench at the bolt head and no room for nuts on the bottom due to bolts proximity to the frame braces. The steering arms are bolted to the spindle assembly bracket with 00-90 bolts as shown in Step 3.

[LR3]

Adding the fan motors, fan blades and the sway bar is step 5.

The fan motors are resin with detailed holes for connector posts. I added 0.08 mm bolts for the wiring because this will be seen through the front grill opening. The fan blades are cut out of thin aluminum sheet. They can just be glued to the motor shaft or a hole can be drilled for a 1mm bolt. I used a #38 drill. I then shaped the blades over a dowel and gave them a gentle bend.

The sway bar completed the activity so far. It is attached to the radiator frame with 00-90 bolts and then the radiator frame is attached to the chassis frame. The sway bar in the real world would have an articulated connection to the front spindle assembly. In the 1/8th world the best we can do is simulate the attachment with a 0-80 bolt that just reaches into the recess hole in the bottom A arm. This hole should be drilled out with 1/16th drill but not penetrate the top surface of the A arm. We don't want a solid connection as we want to be sure of the ride height when we attach the wheels. We may need to slightly modify the coil spring lengths.

Edited January 30, 2011 by LR3

[stump]

Man, I get the feeling life is just about to get reeaall expensive........I SO want one of these.

Great work so far mate.

[GrandpaMcGurk]

Yep...it's developing into quite a kit Gregg. If you think you have bitten by the "Gotta Have One Bug", just wait 'til you see her with the sheet metal interior and fiberglass body in place.

[stump]

Yep...it's developing into quite a kit Gregg. If you think you have bitten by the "Gotta Have One Bug", just wait 'til you see her with the sheet metal interior and fiberglass body in place.

That WILL be worth waiting for, I'm sure Don.

The "Cobra" is an all-time fav......and I sure would LOVE to do one in such an awesome scale. Following along, enjoying this ride a whole lot.

[LR3]

Posting has slowed while waiting for the resin differential but Tim sent me a draft copy of the manual. It is only 100 pages so far; about 1/3rd being B sized drawings. It is a mind-blowing manual. How he conjured up the individual parts, sized and mentally fitted them together to complete the car as a whole is beyond me.

I will post individual pages as I progress through the steps. Just as an example I picked future step 28 to show here. It consists of a B sized drawing then 4 pages showing how to bend the two foot boxes for the interior of the cockpit. The aluminum pieces are to be bonded together with epoxy or possibly CA glue. I am not sure how much of the aluminum I will paint if any. I get the feeling the aluminum will look quite sharp surrounding other painted parts like the motor, radiator, master cylinders, etc. Along with the manual he sent about 50 dozen aluminum parts just to scare me. In the back of the manual is a second copy of all the aluminum patterns. This second copy will be used to cut out and tape directly on the metal part to be bent. I will use the lines on the paper cutout to guide in scoring the backside of the bend with an exacto knife and the actual bending of the parts with pliers.

This is also a good place to mention tools that might not be in your arsenal. One might need to purchase a pair of "duck billed" smooth jaw, needle nose pliers. These pliers will be used like a sheet metal brake to bend the sheet metal parts. The duck bill is necessary because this will give you a nice square and straight tip to bend the small taps and the smooth jaw is needed to keep from marring the aluminum surfaces during the bending process. Also there are over 100 places where you can use 1mm bolts for detailing so one might want to consider purchasing a 1.4mm wrench (Flats are 1.4mm). 00-90 and 0-80 wrenches are handy too.

Edited February 10, 2011 by LR3

[LR3]

The instruction manual in Step 6 calls for assembling the rear drive. The differential provided by the Madd Fabricattor is resin. He suggests the following finish process to insure removal of the mold release:

Initially clean the parts before you primer them with an automotive prep cleaner, which is supposed to remove any wax, silicone, or the like. Then wash the parts in a mild dish washing detergent, rinse well, and let air dry. It might be well to scuff sand the parts with 360 or 400 grit wet/dry sand paper. Primer the parts using a good lacquer based high fill sandable primer such as Dupli-Color High Fill. Once the primer is thoroughly dry any tiny defects can be handled with putty like 3M Bondo, a professional glazing and spot putty.

The axles are a series of universals.

Note: Tim advises that the universals on the two half shafts should be 90 degrees apart from each other rather than as I pictured them. This is the way the real drive shafts are made, it gets rid of some weird harmonic vibrations.

I had rushed ahead before receiving the instructions so the mounted assembly is a little further along than the drawing.

Edited February 12, 2011 by LR3

[Foxer]

Are you sure this won't start up once it's done?

Thanks for enlightening us with this build post.

What an incredible job TDR has done on this!

Edited February 13, 2011 by Foxer