Chapman GP7 Project

Re: Chapman GP7 Project

Postby Marquette » Sun Nov 20, 2016 12:15 am

CFRiad wrote:
ConnRiver wrote:... I've decided I want to continue in TT...

Welcome back.

ConnRiver wrote:... Maybe [...] an RDC can be thought about?

Yay! Cariboo Dayliner.
CaribooDayliner.jpg


That was my first thought, too!
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Re: Chapman GP7 Project

Postby ConnRiver » Mon Nov 21, 2016 8:24 pm

I've lost some momentum but hope to pick it up soon. Working Tuesday and Wednesday, family Thanksgiving Friday, my favorite college team plays football Saturday and we'll be there. But, after that, I'm off work until December 5 so expect to get TT work done.
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Re: Chapman GP7 Project

Postby Bernd » Mon Nov 21, 2016 8:56 pm

Great to hear you're getting back into it.

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Re: Chapman GP7 Project

Postby ConnRiver » Sat Jan 14, 2017 1:20 pm

Thought I should post a word in the event anyone here might wonder what's happening with this project.

I've been working in the shop, lots of work to do. That included moving the spin-caster and the vulcanizer into the basement (heavy stuff, the vulcanizer weighs about 750 lbs, I think, and was moved in pieces). I refinished the vulcanizer cosmetically, cleaning the parts and applying several coats of Safety Blue Gloss spray paint.

The vulcanizer-spincaster casting process, as I understand it, might be as much art as it is industrial technique. I've decided I just don't want to go the resin casting route. I intend to put this equipment up for sale at some point.

Now, I'm in the beginning stage of learning Autodesk's Fusion 360 CAD/CAM software, moving over from less capable software I cobbled together into a process. I think some here are working with this popular software, unless I'm mistaken. I've added a "CAD" monitor (online recommendation of displays best suited to CAD work) to my laptop and added some zip with a RAM upgrade, too.

Plastic injection molding is my goal. I have dissected all the parts of a 5-ton semi-automatic machine from a long-defunct manufacturer, redrawing the parts in 2D and 3D CAD. My goal is to rebuild it to 10-ton performance and automate it with Arduino hardware and applicable software, directing the injector's operation from one of my other laptops. This might ;-) take awhile.

In the meantime, I'll do some CNC cutting on the GP7-20 project as I can. Need the variety of work.

Thanks much for "listening,"

Brian C.
Cedar Rapids, Iowa

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Re: Chapman GP7 Project

Postby Bernd » Sat Jan 14, 2017 3:26 pm

Hi Brian,

Let me see if I understand this correctly. You were going to spin cast resin? Usually using vulcanizing rubber and a spin caster goes with low melting point metal or pewter. Correct me if I'm wrong.

I use two free CAD programs, one from 2016 Dassault Systèmes, DraftSight 2016 x64 SP2 for 2D and DesignSpark Mechanical 2.0 for 3D. Still trying to get my head wrapped around 3D drafting.

Anyway, glad to see you are back at it.

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Re: Chapman GP7 Project

Postby ConnRiver » Sat Jan 14, 2017 4:12 pm

Bernd, hey,

Since I have never spin-cast, take what I write cautiously. But, I thought the metal chassis and the metal weight structure likely could be spin-cast.

However, I have read that using RTV rather than vulcanizing rubber, some have spin-cast resin, too. Although I thought I would probably cast resin the usual way but cure it under pressure and heat, which I've read results in castings with virtually no shrinkage.

Autodesk Fusion 360 is free to students, hobbyists and others with a business income less than $100,000 (I believe I've got that correct). It's an all-in-one CAD-CAM-3D printing software program, I think. (I've only begun to learn it.)

-Brian C.
Cedar Rapids, Iowa
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Re: Chapman GP7 Project

Postby Bernd » Sat Jan 14, 2017 6:55 pm

ConnRiver wrote:Bernd, hey,

Since I have never spin-cast, take what I write cautiously. But, I thought the metal chassis and the metal weight structure likely could be spin-cast.


Ok, that makes sense. Wonder why I didn't come up with that. :doh:

However, I have read that using RTV rather than vulcanizing rubber, some have spin-cast resin, too. Although I thought I would probably cast resin the usual way but cure it under pressure and heat, which I've read results in castings with virtually no shrinkage.


I cast under pressure once after I was told that it would squeeze the bubbles smaller. I found the casting somewhat brittle afterwards. I was/am going to try a spin cast resin one of these days just to see if I can get a better casting. Have you looked into vacuum casting resin?

Autodesk Fusion 360 is free to students, hobbyists and others with a business income less than $100,000 (I believe I've got that correct). It's an all-in-one CAD-CAM-3D printing software program, I think. (I've only begun to learn it.)


Guess that leaves me out. I have a separate CAM program call CamBam that converts DXF files into G-code format.

Keep us informed as you make progress. I know I'm highly interested in what you're doing and love to exchange ideas with you. Not trying to horn in on your project, just friendly banter. :thumbup:

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Re: Chapman GP7 Project

Postby ConnRiver » Sun Jan 15, 2017 3:29 pm

Bernd,

Brittle castings might have more to do with the formulation of the resin than with the pressure, maybe? Many hundreds of resin types out there, as I'm sure you know.

In the past I have read about resin vacuum casting, although at the moment I'm not sure how the results vary between vacuum- and pressure casting. IIRC, some apply vacuum first then pressure? It's been awhile. . . .

Prior to tackling Fusion 360, my process was to CAD draw in 2D, redraw the objects in 3D to confirm fit and appearance, return to the 2D drawing and adjust as needed, export the 2D .dwg file as a .dxf file into CAM software and convert to a .ccd file, work the machining offset paths and convert the resulting CAM file into Flashcut .fgc to create G-code. After that, a bit of G-code editing was required. . . .

As I understand it at the moment, Fusion 360 will do all this and more (not only create G-code for machining from 3D drawings but code for 3D printing, too), much simplifying the process.

-Brian C.
Cedar Rapids, Iowa

Hey, you're not horning in on the project; I wouldn't post it here if I don't value the back-and-forth interchange of ideas here!
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Re: Chapman GP7 Project

Postby ConducTTor » Sun Jan 15, 2017 8:35 pm

I don't have anything useful to add. Just asking you to continue with updates as this is very interesting to me. Thanks.
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