Scratch/Kit Bash SD

[6axlepwr]

I am a creature of vision. I need to see things before I buy them. The one photo on the Mark4 Design page looks exaclty like the photo of 5 years ago. It would be a great benefit to Mark4 Design to post good close photos of the shells he is offering. This would dispell any images I have of them. Posting images of a 3D design is always going to look awesome. I want to see the product. Print one of each shell, Give it a light coat of gray so the detail shows. Then the modeler can make a decision for themselves if it meets their standards.

I apologize if I was taken as disuading people from purchasing the Mark4 Design shells. I set a standard for myself. Not anyone else. Just myself. I am not satisfied with what N-Scale has to offer me. It is why I left so long ago and went to HO. But N-Scale is what I like so instead of pissing and moaning about it, I set out to recreate what I think it should be like for a modeler. Not necessarily a runner, but a scale modeler. If you like the Mark4 Design shells, great. I have not seen one in person that I like YET. I have not seen anyone post photos of any model built with Mark4 Design shells either or heard of ANY reviews. What I spoke of in this thread is my own personal experience. Albeit 5 years ago, but I have not seen any since and the web page looks the same as it did 5 years ago.

When I offer my parts, there will be close up photos of the parts so you can see everything and models built with the parts so you can see how it all looks when placed on a model. Not dark dingy pictures you cannot see anything about the fidelity of the part.

Tonight I cut the battery boxes off an Atlas GP40. Squared them up in my mill and set them in place. They fit nicely. BTW, on this model I have redesigned the deck. I will be attending the St. Louis RPM meet next week. If you are in the area, stop by and say hello. You can see this model in person. It is located in Collinsville, IL. So when I get back I will be putting this new design into action. It will be much better and a much crisper looking deck. I'll give a clue. Think plastic and other materials  .

[johnh35]

Mark, your work is fantastic and your details appreciated.

[Robbman]

Robbman, I think I know who you are and I know the quality of yor designs. I am not at all complaining about the design.

You do... we spent some time together at the VMT

I understand your vision... it's great to push the bar higher and higher... but don't turn into a Christopher Howard please

[6axlepwr]

No, you misunderstood me. In vision I mean I need to see what I am buying. Not vision as I can see the future. I can barely see the models I am working on let alone the future  .

[JoeD]

Welcome to Railwire. 

[lock4244]

This is going to be one interesting build, Brian. can't wait to see the results...

I'm not at your level of prototype fidelity, but need to build a fleet of CN SD40's from Kato cores. Problem is most of CN's 241 (and GTW's 30) were no-DB units, and removing the DB is a real pain in quantity (looking at doing 7-8 units total), and my attempts at fabricating a replacement non-DB section have been, um... not the best, even by my standards. Wondering if you could comment on the feasibility of using just the mid section of a non-DB Atlas GP40 on a Kato SD40? I imagine it would require a slight widening of the Atlas piece, which seems to me could be accomplished with a narrow strip of styrene spliced in. Easier than sawing and filing down the the Kato and fabing a new piece. Unfortunately, I do not put the modeling in model railroading.

Any thoughts?

[6axlepwr]

Unfortunately, I do not put the modeling in model railroading.

Any thoughts?

You only need to make the attempt. The modeling will come from that.

I'll have to check, but I am not even sure the Atlas hood is the same height as the Kato hood. I think Atlas is more accurate. I'll have to check that.

This can be done. But it is going to take a bit of work on the inside of the Atlas shell. The place where you run into trouble is where the Kato frame bulges out around the motor, the bumps that secure the shell and a little at the top of the frame. You would need to grind away the inside of the Atlas shell to fit around the bulge in the frame. You would need to take 0.016" off each inside face. The Atlas shell is 0.030" thick. Next you would need to relocate the bump cavities. Easy to do. After you have cut the inside of the shell to fit over the motor hump and removed 0.015 off the top of the frames highest points, slip the shell over the chassis until it contacts the sill unit. it is going to bulge wildly at the back end where the frame bumps are. Do not worry about this. Just make sure the shell bottoms out on the sill unit. Squeeze the shell firmly over the bumps. You will see a slight whitening where the shell bulges out. Remove the shell and look on the inside. You should see a very small dimple where the frame bumps pushed into the plastic. Use a steel ball cutter, maybe .0625" to .125" in diameter, and cut a dimple into the shell. Next, you will need to reduce how much the frame bumps sticks out. Reduce it by half. Check your fit and if it needs to be reduced more, do more until the shell fits WITHOUT the side bulging anymore.

As for the shells, the Atlas shell I believe is not the same width as the Kato shell. I actually think the Kato shell is slightly wider. So this means when you mate the hood up with the clean air room, the hood will not line up perfectly and you will have a small gap on the left side between the hood and walkway which you could fill with styrene strip. But if you make your cuts right, you may be able to hide this because there is a natural seam between the clean air room and the engine compartment. On the prototype, that seam can be pretty obnoxious at times. From the Atlas shell, cut the clean air room off before the seam between the clean air room and first engine room door. This will also be in front of the exhaust hatch. Finish the cutting just up to the start of the seam. Try to make this as square as you can. Take your time. Use masking tape as a guide if you have to. On the Kato shell you will want to cut past the seam and into the first engine room door. Then clean your cut back to the beginning of the seam on the clean air room.

Gluing the two plastics together is going to be a real PITA also. Atlas used the really nice soft styrene that takes to gluing with solvent cement a real joy. Kato uses ABS which is a real PAIN to glue to anything with solvent cement. So if you are going to attempt this, Make sure the Atlas shell slips over the frame easily. Otherwise at anytime you may want to disassemble the model, the shell pieces may come apart because of the Kato ABS plastic.

[6axlepwr]

I finished splicing the shell tonight and the experiment was a failure when you put in a scale clean air room.

Here is what I found out in a nutshell. The KAto SD40 is innaccurate in hood length. Atlas is accurate. To fit the Atlas shell you have to build your clean air room about 0.040" longer than what it should be. I built my shell to be prototype length and it woul dhave required me to remove a good portion off the rear of the frame To fit the shell on. I now need to gt a new frame from Kato. No big deal. The experiment was worth it. I have an extra Kato drive. I will give Mark4 Design on emore try and see if in fact the quality of the printing has improved. If not I will just make my clean air room 0.040" longer.

[6axlepwr]

It has been confirmed to me that Mark4 Designs has a high end ultra high resolution printing machine and that the shells are better than when I bought my sample five years or so ago. So with this news, I will order a shell and give it a go again. I look forward to seeing what the improved print will look like. Definitely will save me from having to scratch build one.

[lock4244]

You only need to make the attempt. The modeling will come from that.

I'll have to check, but I am not even sure the Atlas hood is the same height as the Kato hood. I think Atlas is more accurate. I'll have to check that.

This can be done. But it is going to take a bit of work on the inside of the Atlas shell. The place where you run into trouble is where the Kato frame bulges out around the motor, the bumps that secure the shell and a little at the top of the frame. You would need to grind away the inside of the Atlas shell to fit around the bulge in the frame. You would need to take 0.016" off each inside face. The Atlas shell is 0.030" thick. Next you would need to relocate the bump cavities. Easy to do. After you have cut the inside of the shell to fit over the motor hump and removed 0.015 off the top of the frames highest points, slip the shell over the chassis until it contacts the sill unit. it is going to bulge wildly at the back end where the frame bumps are. Do not worry about this. Just make sure the shell bottoms out on the sill unit. Squeeze the shell firmly over the bumps. You will see a slight whitening where the shell bulges out. Remove the shell and look on the inside. You should see a very small dimple where the frame bumps pushed into the plastic. Use a steel ball cutter, maybe .0625" to .125" in diameter, and cut a dimple into the shell. Next, you will need to reduce how much the frame bumps sticks out. Reduce it by half. Check your fit and if it needs to be reduced more, do more until the shell fits WITHOUT the side bulging anymore.

As for the shells, the Atlas shell I believe is not the same width as the Kato shell. I actually think the Kato shell is slightly wider. So this means when you mate the hood up with the clean air room, the hood will not line up perfectly and you will have a small gap on the left side between the hood and walkway which you could fill with styrene strip. But if you make your cuts right, you may be able to hide this because there is a natural seam between the clean air room and the engine compartment. On the prototype, that seam can be pretty obnoxious at times. From the Atlas shell, cut the clean air room off before the seam between the clean air room and first engine room door. This will also be in front of the exhaust hatch. Finish the cutting just up to the start of the seam. Try to make this as square as you can. Take your time. Use masking tape as a guide if you have to. On the Kato shell you will want to cut past the seam and into the first engine room door. Then clean your cut back to the beginning of the seam on the clean air room.

Gluing the two plastics together is going to be a real PITA also. Atlas used the really nice soft styrene that takes to gluing with solvent cement a real joy. Kato uses ABS which is a real PAIN to glue to anything with solvent cement. So if you are going to attempt this, Make sure the Atlas shell slips over the frame easily. Otherwise at anytime you may want to disassemble the model, the shell pieces may come apart because of the Kato ABS plastic.

Thanks for the through response, Brian. Seems like there's no free lunch here. I can take a stab at it, but the gluing issue seems to be a deal breaker to me... never even considered that would be an issue. I can see a painted model splitting in half some day, and me being pretty frustrated. I wouldn't want to have a fleet of delicate snowflakes running around. Might be better to just use the non-DB piece from an Atlas shell and avoid having a weak shell.

[Catt]

Here's a older pic of my KATO based GP38.The chassis cab shorthood and clean air room are KATO SD40.The long hood is the ATLAS GP38 unit.Everything fits well and the btwo hood pieces are butt glued using Model Master glue.There is nothing reinforcing the joint and I have had the unit apart numerous times.There also is no misalignment between the two hood pieces.



Ignore the front coupler the previous owner insisted on running the SD40 on 9.75"radious curves.My smallest curve is almost twice that.