# Short Run CNC Machining



## mocrownsteam (Jan 7, 2008)

A very kind fellow live steamer has sent me CAD files (Solidworks 2010) for driver centers. Is anyone aware of short-run CNC maching companies who would handle a small job. Would be really nice if they were in New England and could work in brass, but I'm open on materials.
Thanks
Mike McCormack
Hudson, Massachusetts


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## Kovacjr (Jan 2, 2008)

What type pf driver are you making? Scale, size?? I know someone that can mill it out, another that can just cast the centers in brass with a master made. Might be good route. Then press into tires.


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## Chris Scott (Jan 2, 2008)

*[url]http://www.emachineshop.com/*[/url]


Search on SolidWorks for how to submit.


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## Mark Scrivener (Jan 7, 2008)

Mike,

Machine shop time is not inexpensive, but CNC machines can be. I'm not sure how you plan on completing the rest of this project once you have the drivers, but there are quite a number of us in this hobby who have home machine shop equipment - and many have CNC.


Attached photo shows my CNC mill. I recently added a 4th axis (rotary table). My total investment with software, enclosure, tooling, etc is around $3k. This machine will cut brass, stainless (303 at least), and most other materials you might want to work with. Yes, there is a learning curve, but it isn't that bad and can be quite fun. 

For not much more you can have a significantly larger machine. You can also spend less. 


Just something to consider.....

Mark

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## mocrownsteam (Jan 7, 2008)

Thanks for the good responses to my question. 
Jason: The driver is a 48" driver in 1:20.3. The files will make up a driver center. I think casting is out due to the shrinkage factor (that was not allowed for), so it's CNC machining. 
Chris: That is the company I was looking for. I had bookmarked their site before my hard drive failed and I lost it all. Thanks! 
Mark: I'm still very early on the learning curve for CAD (TurboCAD) but ultimately I can see a CNC Sherline size mill in the basement. All my machines now are manual operation and I manage to kill a lot of virgin brass. I suspect with CNC I'll be able to do it more efficiently! VBG! 

Mike McCormack 
Hudson, Massachusetts


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## Jack - Freshwater Models (Feb 17, 2008)

Mike, 

Casting isn't necessarily out of the question. If you have a cad model then you can scale it to correct for shrink if it is criticle. Best option might be to have the driver 3D printed and cast from the printed pattern. 

One issue with cnc machining is getting into all the little corners. A 3D printed pattern doesn't have this problem. 

Is there a reason you don't want it machined or cast in iron? Iron is pretty easy to machine and would make a nicer driver IMHO. 

Jack


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## Pete Thornton (Jan 2, 2008)

The driver is a 48" driver in 1:20.3 
Mike, 

I know of two existing sources of 48" drivers. 

Dave Queener is still working on his std gauge locos, and he has 48" tires and (maybe) 44" wheel centers. I have some of the tires, but maybe he hasn't done the spoked centers yet? In any case, they are probably std gauge style, with lots of spokes. 

Rich Yoders' EBT Mikado has steel NG-style 48" drivers, and he could probably get some from the factory if you asked nicely. They are rim-insulated, which is a nice feature.


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## Gary Armitstead (Jan 2, 2008)

"All my machines now are manual operation and I manage to kill a lot of virgin brass. I suspect with CNC I'll be able to do it more efficiently!" 

Mike, 

I programmed and operated Haas CNC mills in my other life B.R. (Before Retirement). CNC isn't completely fool-proof. You can STILL make mistakes except you can make the mistakes soooooo much faster! He. He. I agree with Jack about having your cad 3-D printed and casting from that. Picking out little corners on CNC is a PITA. 

Good luck with your project.


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## mocrownsteam (Jan 7, 2008)

Thanks for the inputs, 
Gary: You are the second person who suggested doing them as castings. I think this is the way to go. In my non-CAD background I did not realize you could compensate for shrinkage. Live and learn! 

Pete: I'm aware of David and he will be having 12 spoke driver centers cast in brass soon. I did email Rich Yoder about left over drivers at his builder. He did email back that he would ask, but nothing more at this point. Assume that Chinese New Year has caused issues. I'm actually trying to build EBT #14 in live steam as I think I won't ever see one any other way. I hope I'm wrong on that score. 

Thanks to everyone for their inputs. Anyone have any Palacina Productions drivers in their "junk" box? 

Mike McCormack 
Hudson, Massachusetts


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## Jack - Freshwater Models (Feb 17, 2008)

Posted By gary Armitstead on 23 Feb 2010 04:34 PM 
"All my machines now are manual operation and I manage to kill a lot of virgin brass. I suspect with CNC I'll be able to do it more efficiently!" 

Mike, 

I programmed and operated Haas CNC mills in my other life B.R. (Before Retirement). CNC isn't completely fool-proof. You can STILL make mistakes except you can make the mistakes soooooo much faster! He. He. I agree with Jack about having your cad 3-D printed and casting from that. Picking out little corners on CNC is a PITA. 

Good luck with your project. 

Gary,

Aw common, ya just put the stock in the vice and push the botton and it spits out a part! Don't we wish!!!!! Make mistakes? Oh yah, sometimes they get expensive. 

Regards,

Jack


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## Gary Armitstead (Jan 2, 2008)

Hey Jack, 

It's funny that you make the comment about "just push the button and it spits out a part!" Most folks (NOT familiar with CNC) truly believe that AND they expect the part at one-quarter the price! Yeah. Right. We agree. Been there. Done that.


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## Jack - Freshwater Models (Feb 17, 2008)

Gary, 

Well, it is fun after all isn't it? 

I just ran a CAM simulation of millng out one of the driver centers at 20ipm and it runs 7hr35min. Yikes! I've never run that long a program. I think printing the pattern will be a whole lot cheaper and look a lot nicer. If it were me I would include the tire in the casting. 

Interesting project though. 

Jack


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## Pete Thornton (Jan 2, 2008)

trying to build EBT #14 in live steam 
Mike, 

Dr Rivet has an RYM #15 and figures an Accucraft K-27/28 boiler would fit nicely. . .


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## mocrownsteam (Jan 7, 2008)

Pete,

Yes, I could believe that as the EBT Mikes are pretty close size-wise to a K-27/28. The only drawback for me is the $3K price tag on the EBT electric Mike. I can justify lots of hours in the basement killing virgin brass to make my own model as I work real cheap!

Mike McCormack
Hudson, Massachusetts


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## Mark Scrivener (Jan 7, 2008)

The link below shows drivers for Kozo'z A3 (in 3/4" scale) made with a desktop CNC machine. Note that he does the main cutout with CNC and then "cleans up" with a dremel. I don't know what his machining time was per wheel, but I'm guessing it was no more than 1hr based on the amount of coolant used from his mist system (I have the same mister). 

http://thehobbyistmachineshop.com/PenA3/HTML/PA3_drivers.html 

Not that bad - but I agree, if you can go the casting route, why not. 

"Push the button and the part comes out" - where can I get that upgrade for my machine? 

Mark


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## Semper Vaporo (Jan 2, 2008)

Posted By Mark Scrivener on 24 Feb 2010 11:22 AM 
... 

"Push the button and the part comes out" - where can I get that upgrade for my machine? 

Mark 

That upgrade is available from the "Paper*Mate" pen and "Deluxe Check" printing companies. You use the pen to write your name on the bottom line on the right and leave the other lines blank on the paper from the printing company. Send the piece of paper to any reputable machining company and the parts will "pop out" on a schedule based on how many commas (or periods, if you follow the non-U.S. method of demarking 1000's in your monetary accounts) are available in the account indicated by the pre-printed numbers at the bottom left of the financial instrument.

Simple, safe, fast (if ya gots the dollars!).


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## Gary Armitstead (Jan 2, 2008)

Jack, 

That seems like a very long runtime for that part. I used to run my toolpaths through a "filter" and I could shorten my cycle time by as much as 50-60% on average. If I remember correctly the longest cycle time I ever ran on a die was about 8 hours. From roughing through finishing. This is Finkl die steel-FX2 48 RC. Die block size 10 inch X 10 inch X 24 inch. Carbide cutters mostly, some high-speed.


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## Jack - Freshwater Models (Feb 17, 2008)

Posted By Mark Scrivener on 24 Feb 2010 11:22 AM 
The link below shows drivers for Kozo'z A3 (in 3/4" scale) made with a desktop CNC machine. Note that he does the main cutout with CNC and then "cleans up" with a dremel. I don't know what his machining time was per wheel, but I'm guessing it was no more than 1hr based on the amount of coolant used from his mist system (I have the same mister). 

http://thehobbyistmachineshop.com/PenA3/HTML/PA3_drivers.html 

Not that bad - but I agree, if you can go the casting route, why not. 

"Push the button and the part comes out" - where can I get that upgrade for my machine? 

Mark 

The drivers shown are VERY crude. Note the spoke cross section. My guess is that it was probably manually programed. When you add all the proper shapes including fillets the program gets complicated. That being said much depends on what the modeler wants. Sometimes simple shapes are just fine.

Jack


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## Jack - Freshwater Models (Feb 17, 2008)

Posted By gary Armitstead on 24 Feb 2010 11:46 AM 
Jack, 

That seems like a very long runtime for that part. I used to run my toolpaths through a "filter" and I could shorten my cycle time by as much as 50-60% on average. If I remember correctly the longest cycle time I ever ran on a die was about 8 hours. From roughing through finishing. This is Finkl die steel-FX2 48 RC. Die block size 10 inch X 10 inch X 24 inch. Carbide cutters mostly, some high-speed. 

It uses a 1/8" ball end mill to fit into all those tight curves. I am somewhat limited by my cam program in that I can't set up for round stock. Horizontal roughing takes a little over two hours and the rest is radial finishing. The draft in the part eats up a lot of time since there is no easy way to machine it. Given a simplified design w/o draft (I'm working from what Mike gave me) I think the time might be about 3 hrs. 

You probably had the advantage of high end cam like Mastercam or Gibbs along with a very rigid machine. I don't have 4th axis and don't have some of the features in high end cam.

Jack


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## rwjenkins (Jan 2, 2008)

Another option would be to wait for the Accucraft EBT 12's to come out. According to their website they have asked their supplier to provide them with 3% spare parts for all future brass models, so in theory they should have some spare drivers available when the engines arrive. However, considering their latest product update has no mention of the #12, but does have the South African 2-8-2 with an estimated arrival of October 2010, it sounds like it could be a long wait!


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## mocrownsteam (Jan 7, 2008)

Richard, 

Thanks for the idea, but I'm 58 and I don't know if I will outlast Accucrafts schedule! VBG! 

After reading all the responses to the question I suspect the best idea is to set the CAD files to allow for 5% shrinkage, have the masters made by 3D prototyping and then have the driver centers done in lost wax casting. Then make tires and press on. Jack has been looking at the files and I'll have to get with him tonite via email to see if he agrees. 

Mike McCormack 
Hudson, Massachusetts


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