Buicknutty Posted May 24, 2022 Share Posted May 24, 2022 I do follow your posts, Roger, even though I only post from time to time. Your work so amazing and you are so forthright with the things which don't work so well, at least at first! Keith 1 1 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted May 25, 2022 Author Share Posted May 25, 2022 Yesterday, I did a test with the new product by mixing two parts from the base with one part of the harder. Not too much: 6 grams! Just to see if this product will have the expected properties for the half molds. This morning, the mix is almost tack-free. One of the big advantages compared to the polyester resin: no smell! 4 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted May 25, 2022 Author Share Posted May 25, 2022 As I wanted to have a functioning rear suspension, I did the torque tube. Its length is critical because the wheelbase is managed by that tube. That element is not yet ready: I have to add the bracket for the strut rods. Without those struts, the rear axle is unstable and, in real life, the differential carrier could be bent by driving on a rough road. I will also have to modify the "shoes" for the rear axle; I did its top surface parallel to the pinion; it must be at an angle to match the transmission's end without binding. 12 Link to comment Share on other sites More sharing options...
Laughing Coyote Posted May 25, 2022 Share Posted May 25, 2022 Just amazing work as always! 2 1 Link to comment Share on other sites More sharing options...
Paulie9fingers Posted May 25, 2022 Share Posted May 25, 2022 That looks amazing 1 1 Link to comment Share on other sites More sharing options...
drhach Posted May 25, 2022 Share Posted May 25, 2022 That's really coming together nicely. I can't wait to see it with the new tires. 2 1 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted May 26, 2022 Author Share Posted May 26, 2022 8 hours ago, drhach said: That's really coming together nicely. I can't wait to see it with the new tires. Me too! 2 1 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted May 30, 2022 Author Share Posted May 30, 2022 With the addition of the struts, the torque tube is now complete. If you are looking at the picture, you'll see that the thread near the tube is much longer than the one towards the wheels. There is a reason for that. Which one? 6 Link to comment Share on other sites More sharing options...
Paulie9fingers Posted May 31, 2022 Share Posted May 31, 2022 I have no idea why the threads would be longer at the torque tube. 1 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted May 31, 2022 Author Share Posted May 31, 2022 To attach the rods to the drive axle, the nuts at both sides must be screwed in before the installation. If the threads are not long enough, at least on one side, it would be impossible to insert the rods...Therefore, the nuts at both ends are installed till the end of the thread and then adjusted to have the proper geometry at the rear axle. No matter if the car is scale 1:1 or 1:12, the procedure is the same! 3 Link to comment Share on other sites More sharing options...
Paulie9fingers Posted May 31, 2022 Share Posted May 31, 2022 1 hour ago, Roger Zimmermann said: To attach the rods to the drive axle, the nuts at both sides must be screwed in before the installation. If the threads are not long enough, at least on one side, it would be impossible to insert the rods...Therefore, the nuts at both ends are installed till the end of the thread and then adjusted to have the proper geometry at the rear axle. No matter if the car is scale 1:1 or 1:12, the procedure is the same! That makes perfect sense now that you've said it 😂 2 1 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted June 1, 2022 Author Share Posted June 1, 2022 Before I go to the rear brakes (as the rear suspension is a necessity to do that), I wanted to continue with the tires. The next step is to create the negative molds with a suitable material. I began with the side walls, allowing enough space between the RTV molds and the exterior diameter. Then, as I did long ago, I attached the walls to a brass plate with masking tape. Then I did a mix with resin and hardener and evacuated the trapped air. After the majority of the bubbles was gone, I poured the liquid into the molds; then the trouble began: as the mix is also as thin as water, the resin began to soften the glue from the tape and oozed out. I tried to do a dam with the plasticine; it was good for a few minutes, no more. To reduce the gap between the plate and the walls, I put some weight on the walls. This reduced somewhat the "flow", but not stopped it. During almost the whole afternoon, I catch as much resin as possible and put it back where it belongs. When the resin began to get thicker, I could do something else. The next morning, the resin was almost set and I began to remove as well as I could the masking tape and the oozed resin. One thing is sure: that product stick well on brass! In one or two days, I will take the RTV molds away. For the moment, the product is still flexible. Remember: on the notice, the material is set after 15 days! 5 Link to comment Share on other sites More sharing options...
Paulie9fingers Posted June 1, 2022 Share Posted June 1, 2022 I hope everything works out and they are usable 1 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted June 1, 2022 Author Share Posted June 1, 2022 Me too! 2 Link to comment Share on other sites More sharing options...
Paulie9fingers Posted June 1, 2022 Share Posted June 1, 2022 The worst thing about lengthy projects like that is when it doesn't work out it, it sets you back a fair amount of time. If it's something that takes an hour or two and it doesn't work out then it just takes another hour or two, this is another two weeks 😲 3 1 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted June 3, 2022 Author Share Posted June 3, 2022 Half success...This morning, I separated the molds from the brass plate. I noticed that the RTV went under the positive molds; this is the first time that it happened. I will have to remove some material from the negative mold's flange, otherwise the tires will be too wide and the width irregular. There are some tiny bubbles which did not went away; I don't think this will be an issue with the tires. I had to cut the center of the positive molds to remove them from the hardened resin; if I would do new half molds with the resin, I would have to do new positive molds because I need the center to locate the half molds during the tires "production". 6 Link to comment Share on other sites More sharing options...
Paulie9fingers Posted June 3, 2022 Share Posted June 3, 2022 So will you be moving forward with these molds ? Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted June 3, 2022 Author Share Posted June 3, 2022 Yes, otherwise I would be two steps back! 3 Link to comment Share on other sites More sharing options...
John S. Posted June 3, 2022 Share Posted June 3, 2022 Roger, I have been following your build on the Cadillac since the beginning. Just like all of your projects, the work is amazing. There are no words for the talent that you have in your skills as a builder. Just keep building! 2 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted June 4, 2022 Author Share Posted June 4, 2022 Thanks, John; I'll do my best to continue! 2 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted June 5, 2022 Author Share Posted June 5, 2022 Parallel to the tire saga, I'm continuing with the torque tube/rear brakes. There is a relay between the main actuating lever and the rear axle which is attached to the torque tube. Honestly, I don't know its purpose; there must be one... Anyway, I finished both pieces just to discover that either the brackets screwed to the torque tube are too short or the levers are too long: if I had the rods going to the rear axle, they would touch the rods which is not good. By looking at my pictures, it seems that the levers are too long. However, I will redo the brackets, there is less work involved. 6 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted June 7, 2022 Author Share Posted June 7, 2022 I could do and install the various rods to the rear brakes. During the rear springs flexion, I expected a movement at the levers located to the rear axle, but there is none. Of course, my linkage may have some unwanted play, leading to the illusion. Anyway, the rear brakes are functioning when I'm pushing the brake pedal and I see that the hand brake lever will do the same when installed. As I have to put the frame on its back, I removed the hand brake lever because it's taller than the engine. There is an inconvenient: the rods are not coming back to the release position because I skipped a spring located on the brake shield. I will have to add them. As I don't have a die to cut the threads on the rods, which are 0.8 mm in diameter, I had to cut bolt's heads and silver solder the threaded part to the rods. I calculated that the rods are able to withstand a force of up to 6.5 kg before they break. I will never go that far! 6 Link to comment Share on other sites More sharing options...
keiser31 Posted June 7, 2022 Share Posted June 7, 2022 Roger, I am absolutely astounded by the detail work that you do! I LOVE that it looks SO real. 5 1 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted June 9, 2022 Author Share Posted June 9, 2022 The first tire is born. Unfortunately, I cannot use it because it's too wide! I had several issues when I did it and the RTV began to set when I put both halves together. I also noticed that there was material to remove at the half molds; not much, about 0.5 mm. Today, I did another try. Some explanation are needed to understand the process. I know that it was already published, but it was more than 10 years... The attached pictures are as follow: First, I'm purring some transparent RTV into a cup, about 50 grams for one tire. Then, I'm mixing a tinting product as transparent tires are silly. The hardener is then mixed. I'm using a small cup for that, but at the first tire, while removing the trapped air, I saw that the volume increased so much that I had to stop the vacuum pump. I transferred the mix into a larger container so an overflow did not happen. After about 15 minutes, all air is removed so I could purred the mix into the half molds. This operation is again entrapping air so the half molds are back into the desiccator. Again, to avoid overflow, the half molds are not completely full. After 10 minutes, both molds are taken out and more RTV is added as you can see on the next picture. Up to that, 3/4 hour elapsed. After one hour, the curing begin slowly. Then, I have to monitor when the mix will begin to set. Too early, the product will escape and create an air bubble; too late, the excess material cannot escape and the tire is too wide. After 1 hour and 15 minutes, I put both halves together and pressed them together to evacuate the excess material. This time, it could be that I was 3 minutes too late. I added some weight on the assembly; I will open it tomorrow as 10 to 12 hours are needed for a complete setting. 6 Link to comment Share on other sites More sharing options...
Pat Hollingsworth Posted June 9, 2022 Share Posted June 9, 2022 Upon seeing that latest view of the chassis, I realize how many jewel-like pieces are going into this project! I thrill with the ingenuity of the Cadillac designers and the master in Switzerland that is replicating their work in miniature form. Wow- that simple word, really says as much as anything to describe the results from both 'shops'. Roger, I sure am glad I didn't get the job of making those tires. I look at the process and know, absolutely, that it is not something I'd ever master. You, are a wizard and problem solver, par exellence! My hat is off to you once again. 2 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted June 10, 2022 Author Share Posted June 10, 2022 Thanks Pat! Yes, doing the tires is a complex matter. This process is not mine: a famous model builder, Gerald Wingrove, described it in his book I bought in Reno for about 40 years! 2 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted June 10, 2022 Author Share Posted June 10, 2022 One of the first things I did this morning was to open the molds! That story in pictures: the weight is off, the molds are ready to be separated. The light gray surfaces are an indication that there is already a slight separation between the mold and the RTV rubber. With a screwdriver, I'm forcing the separation. If I had slicks there would be no problem but the thread is offering some resistance. This is the crucial question: can the mold withstand the effort? One half is away, no issue. Now, by pushing and pulling, the tire is coming out of the mold. Fortunately, this is a good tire. I cut the rubber which oozed between parting lines with a tool. The middle must also be cut away. The tire is installed on a wheel. I noticed a difficulty with the white wall: there is a void between it and the tire. The reason is simple: all my white walls are too thick; when removing some material, the fit is excellent. Now I can do the other tires, one each day (more or less...). 12 Link to comment Share on other sites More sharing options...
Laughing Coyote Posted June 10, 2022 Share Posted June 10, 2022 Oh my, just incredible Roger. 2 1 Link to comment Share on other sites More sharing options...
Randiego Posted June 11, 2022 Share Posted June 11, 2022 Roger, Not only are you a mechanical engineer, you can add "Petrochemical Engineer" to your sheepskin ! ! I wonder if Michelin, Firestone, Goodyear, Goodrich, Yokohama had as many "trial and error" runs as you have had? Being the mechanical mind that you are, you think through all the steps before you act. But.......materials do not always cooperate. Brass, aluminum, steel all have their properties and are not complicated once you get experience working with them. But synthetics poses a whole different set of problems. One question I have; Are the materials that you are using today the same as what you were working with when you were making the Continental tires? Or have they changed since then? Seems that you had more issues with these tires than with the ones for your previous models. And was Gerald Wingrove using the same products that you are using today? Have they changed in composition from what you used in these tires? So many products have been eliminated these days due to "environmental" concerns. We no longer can use the good paint (lacquer based) here in California. They can only use "water based" paint in the repair shops. I have to drive to Arizona to get the paint that I once was able to buy here. I have a solvent tank for cleaning parts and I could get the solvent inexpensively ($15.00 for a 5 gallon bucket) Now that same 5 gallon bucket costs me $67.00 plus tax. And I am lucky to get it. SafetyClean, who have solvent tanks at the local auto repair and transmission shops can no longer supply them with solvent. Mainly, it is a soap solution! Try cleaning up an engine block or transmission case with caked on gunk with soapy water ! My friend, who owns a shop told them to take their tank out. He found that "Simple Green" worked better than their product. First, he power washes the block/case at his outside pit. (he did not have to do that with the old system) then the part is put into the vertical wash tank and the fluid is heated to 150 degrees. It has worked O K, but not as good as the previous solvents that he can no longer get. Such are these times. Randy 2 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted June 12, 2022 Author Share Posted June 12, 2022 Your are right! Chemical products have also their properties but, as they are mixed together, many factors are sometimes difficult to control: is the mix humogen? Mine is obviously not: in the cup I'm using, there is some material which is not used after both halves are filled up. I can see that at some points, the curing is more advanced than at another point, even if I have the impression I'm mixing correctly the base material with its hardener, which is obviously not. Temperature is also a factor, maybe humidity, but I'm not sure. Anyway, the tire from yesterday is not good: I put both halves together maybe 5 minutes too early. The result: two small air pockets at the rear and some thread which is gone. As the car has two spare wheels with a cover, the tire will not be seen. I hope that the one from today will be better... About the material: the white RTV I used for the molds is from the same supplier, but the formula changed. Better, worse? I cannot say. The transparent product used for the final tires is the same as I used for the Avanti and Mark II. The resin for the molds is different, but is is more agreeable to work with it compared to the polyester resin I used before. The separating wax is from the same brand, but it leaves a surface which is not so smooth than before. The result is a tire which looks like is was sandblasted. California is probably the most extreme State about regulation. The other ones will get the same rules sooner or later, Europe too... 4 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted June 12, 2022 Author Share Posted June 12, 2022 Now that I'm more or less confident with the tires "manufacturing", I would like to refresh the steps needed for that. 1. make a master tire with brass or something which can be machined 2. make half molds from the master tire; they are negative molds 3. make positive molds (or two half tires) from the negative molds 4. make negative molds with a resin which will be hard after curing 5. finally by using the negative resin molds, do the final tire (s) I see an argument: why don't use the half molds described under the point two? By using those RTV molds, it would be necessary to use separating wax for each tire. This is not a big deal, but if the wax is not going everywhere, the tire will get bonded with the mold, destructing it. The next argument with the way I'm doing the tires: by applying much pressure to the soft molds like shown with the attached picture, I doubt that the end result would be usable. 4 Link to comment Share on other sites More sharing options...
John S. Posted June 14, 2022 Share Posted June 14, 2022 Roger, you are as good as it gets! 1 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted July 14, 2022 Author Share Posted July 14, 2022 Back from vacation...Work will resume soon! 7 Link to comment Share on other sites More sharing options...
Paulie9fingers Posted July 15, 2022 Share Posted July 15, 2022 19 hours ago, Roger Zimmermann said: Back from vacation...Work will resume soon! Hope you enjoyed yourself 1 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted July 15, 2022 Author Share Posted July 15, 2022 Sure! We had first a 5-days tour in Germany with the "Grand European" (a Cadillac meet) and then 3 weeks in our vacation house. 4 Link to comment Share on other sites More sharing options...
Pat Hollingsworth Posted July 15, 2022 Share Posted July 15, 2022 Did the model make the trip for 'show and tell' at the Cadillac meet? Sounds like it was a really nice getaway. Welcome home, Roger, we missed ya! 1 1 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted July 16, 2022 Author Share Posted July 16, 2022 No, Pat, the model did not make the trip. To be right, I did not think about that! Anyway, there was no appropriate room for that and, with more than 100 people, and rather high temperatures, I don't see how the model could have been favorably shown. But, interestingly, one attendant (a German I believe) spoke to me about that model; he is also following my little steps on the forum! 1 Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted July 18, 2022 Author Share Posted July 18, 2022 Due to the GE (the Cadillac meet) and summer vacation, there was nothing to report. Now, I'm back and some progress was done: most tires are ready, I intend to do a last one in the next few days. With enough tires for the model, I had to do the knuckle arms to be able to install the front wheels. The shock absorbers are temporary installed too; I still have to do the actuating arms. Now, I will do the tie rod ends and the tie rod because it's annoying when the front wheels are totally independent from each other... 10 Link to comment Share on other sites More sharing options...
Paulie9fingers Posted July 18, 2022 Share Posted July 18, 2022 It looks amazing 😎 2 1 Link to comment Share on other sites More sharing options...
Buick 59 Posted July 18, 2022 Share Posted July 18, 2022 WOW! 2 1 Link to comment Share on other sites More sharing options...
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