16 replies to this topic

[Dennis David]

I have a friend (Sandy Grant) who I hope will post here on how he uses a CNC Mill to create a MOLD for the manufacture of a PETG slot car body. I found this video interesting with regards to tool selection. Follow this link for material that could be used in making a mold.
 
https://www.freemansupply.com/
 
https://youtu.be/p4HJAjS78Ms

[Ecurie Martini]

It would be interesting to see.  I believe that most molds for parts with complex curves (like slot car bodies) are done with EDM these days.  Because this application does not anticipate 100,000 parts, aluminum is certainly the material of choice. (At one time, I worked for Bayer.  Our division was the largest manufacturer of disposable plastic petri dishes in the world.  Our largest machine was a 250 ton (clamping pressure) toggle machine with a 36 cavity mold - it was steel.

 

The opportunity that intrigues me is offered by progress (i.e. better, cheaper) in 3D scanning + 3D printing.  You could take a model of any car and scan it to a file.  The model scale wouldn't matter - the file can be resized.  A 3D drafting program could then be used to define thickness and interior features - mounting posts etc. and the lot fed to a 3D printer.

 

An engineer friend (Jim Butt) and I rolled this around years ago.  At the time the scanner + printer gear was at least $25K - a lot less now.

 

EM

[Dennis David]

If you are making slot car bodies I understand you should consider RenShape Modeling and Styling blocks. Area71 uses SLS 3dp to make his bodies in Nylon and then adds a proprietary post process to make his bodies (20-26gr for 1/24 GT Coupe) super smooth.

Materials have really progressed Alan. Immense Miniatures sculpts a driver head/figure in clay, does a 3D Scan and then 3D prints in 1/32 and 1/24 Scale.

[Dennis David]

Thingie mounds (Courtesy of Sandy Grant) and master using CNC Mill and Modeling blocks. More complex shapes require a 4th and 5th axis but in milling but can be more easily printed.

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[Dennis David]

For more detail you could scan the car, bring it into Onshape and make any modifications. A friend of mine reverse engineers images created in racing games and loads them into a 3D program, then prints them, never using a scanner.

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[Dennis David]

Still free without limitations if you don't mind your files being in the public domain.

[MattD]

Amazing stuff, more power to you Dennis for trying to learn this new technology. I've got some of the Immense Minature stuff and it is really something.   The Jim Clark driver head is Jim Clark!

[Dennis David]

Thanks, since im not worrying about a certain motor I have more time on my hands. LOL

The 1/3 Sculpture is 3D Scanned and DLP printed.

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[olescratch]

Looking good to me!  How can I get my hands on one of the Thingie bods in 1/24 scale?

[Dennis David]

They are in 1/24. Ask Sandy Grant on FB

[Half Fast]

 More complex shapes require a 4th and 5th axis but can be milked or printed.

 

I get the X Y and Z axis, but what are the fourth and fifth axes?

 

Cheers

[Dennis David]

The fourth axis allows you to hold and rotate the material similar to a lathe. These are really nice milling machines.

[Dennis David]

5-axis Pocket NV v2 I think my head would explode if I had to check the g-code on this one.

[Phil Hackett]

Just curious... what program generates the g-code from the scan? Is g-code even used in these machines?

 

Most of the sufaces you see are made with ball endmills using *very* small step-overs on the finishing pass(es). Even then, polishing will be required although should be usable in most "hobby" purposes right out of the machine. The trick is keeping the most effiecient part of the ball in contact with the work... that's a lot of math!

 

Anything over 3-axis work requires a computer, the exception is simple rotary work with a 3-axis job, so, yes, a 5-axis machine requires matching CAD/CAM and the knowledge to use it.

[Dennis David]

Scan would have to be converted into a vector drawing. Not sure where scanning entered the picture. Did I make a mistake somewhere?

I will be using ESTLCam that creates g-code and use g-code sender to interface with the controller.

Other software is Meshcam, Mastercam and Solidcam.

[Dennis David]

From what I understand g-code does not really cover 4th and 5th axis so I am assuming that these are extensions that require software drivers that are written for a particular machine.

All early days and most maker type machines at this stage come with with their own Cad/Cam software. Thats the issue with machines from China. Youre on your own.

Does that make sense Phill? These are all computer controlled.

[Dennis David]

Oh ok, two many threads hear in one topic. The immense miniature is scanned. None of the other stuff is. Sorry for the confusion.