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08-29-2013, 08:33 AM
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Join Date: Dec 2008
Location: Redmond, WA
Posts: 269
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CNC Milling Machines
Thinking about a CNC Milling Machine to manufacture custom RV parts, even though I had to give up the core RV-9 project, as some may recall.
More precisely, thinking about a Grizzly G0704 and then converting it to CNC.
I acknowledge that this is a bit unrealistic in that I will only be able to use the machine for a bit less than a year. (Again, those who know why I had to give up the project also know why this is true.) But I miss the building game too much to just cave altogether...
Any input or thoughts? NOT interested in anti-Grizzly/Chinese religious rhetoric.
Thanks!,
Mike
__________________
-- Mike Culver;
RV-9 project sold  but details of the build at
www.mculver.com
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08-29-2013, 09:15 AM
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Join Date: Jun 2006
Location: 8I3
Posts: 3,564
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If you want accurate parts you really need to have ballscrews on the machine. I have two machines, one a Bridgeport series 1 CNC and a Lagun FTV-2S converted but no ballscrews. I have much more X-axis travel on the Lagun (52" table) which comes in handy for doing things like instrument panels.
Better off to buy a used machine that was built as a CNC and then just buy some Gecko's, an Ethernet Smoothstepper and Mach3 and upgrade it.
A good friend converted my old mill which was a Chinese RF-31 and it works acceptably well, but he's been wanting to convert to ballscrews.
By the time you're done you will have more $$ converting a Chinese machine than you would to buy an older heavy machine.
__________________
Please don't PM me! Email only!
Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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08-29-2013, 09:22 AM
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Join Date: Sep 2012
Location: 07TS
Posts: 472
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Depending on what you want to cut, and how big you need you might look at romaxxcnc or sherline. Both are pretty decent machines that don't cost a fortune.
-Dan
__________________
Dan Weyant
RV-9A N96KD
Done and Flying 4/30/2015
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08-29-2013, 09:43 AM
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Join Date: Apr 2008
Location: broussard louisiana
Posts: 155
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Haas has some good machines for the money. Look on ebay for a tool room mill. Good bang for the buck. Search for haas TM-1
__________________
Ben Bell
RV8 (sold)
Awaiting Kitfox SS7 kit
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08-29-2013, 10:58 AM
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Join Date: May 2006
Location: Boone, Iowa
Posts: 342
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We used to have a Ron fu with CNC. It was okay for 2.5d work or just drilling holes, but not much else. Ours had stepper motors with no resolver feedback, so if it got off somehow it didn't know it. Finally gave it away to get rid of it.
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08-29-2013, 11:47 AM
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Join Date: Dec 2010
Location: Redlands, CA
Posts: 176
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Mike,
We tried going down that road a few years ago to meet similar requirement. After looking at what was involved to convert a Bridgeport or one of the readily available mills like the one from Grizzily and putting some value on our time we purchased a new Asian mill that had been converted to CNC by a manufacturer here in So. Cal. We realized that by the time that we spec'd. out the necessary components, sourced them, came up to speed on the necessary software, and got the machine up and running we would have spent a lot of time and $$ and still would not have any chips on the floor.
I can say that the mill has been a real asset in one way as we are able to take ideas form a 3D model in Solidworks or Alibre to actual parts in some cases less than 30 minutes. However our experience with our particular machine, controller, and software and because of the limited support from the manufacturer our experience with the converted CNC mill has been very frustrating. A few months into ownership we realized that the amount of money we had spent, the broken tools, scrapped parts, lost time added up to more than we would have spent on a used full up CNC mill from HAAS or a new machine from Tormach or similar that has been fully integrated as a CNC machine and not a conversion.
Personally from what I have seen and people that have owned the machines if I needed a CNC machine for a small shop I would seriously look at the products from Tormach.
http://www.tormach.com/mills-and-mil...cessories.html
I would also suggest that you consider an alternative to purchasing a machine that may provide you the ability to manufacture the parts you need with higher quantity and at a relatively low cost. My suggestion would be that if you do not already have it get a software seat for a good 3D modeling software package and learn how to use it. You will need this for your CNC machine anyway. We have had good experience with Solidworks ($$$$) and surprisingly the sortware form Alibre has been a good value, has good support and we are able to do almost as much as we can with our Solidworks seat. The second thing that I would do is to find a couple of CNC shops that are willing to make parts for you to fill up dead time on their machines. We did this by purchasing a software license for the same software that the shop uses to generate the G code files for their machines. We then provide the shop with the materials, the G code files, a 3D rendering, and drawing for the part. The shop checks our G code file and runs our parts. Works well and we get good parts off of a high quality machining center without tying up a lot of capital on a machine that would sit idle most of the time. We also have a relationship with a local facility that trains CNC machinists and we are able to provide them real world projects to work on. We get good parts, costs are low and it is a WIN-WIN for both sides as we get to help put folks into the workforce with skills that help them earn a living.
Bottom line for us -
Would I convert a mill to a CNC machine? - Absolutely not unless this was my hobby. A lot like the reasons for building your own airplane in that respect.
Would I purchase a CNC machine for inhouse use? - I probably would do it again but I would spend a few more $$ up front for a machine that I had good confidence in support form the manufacturer and other owners. Saving a few dollars wil,l cost you much more in the long run.
Would I develop the skills necessary to design part using 3D modeling tools that I could have others manufacturers and then spend te time to find a shop that will work with me to preform the manufacturing? - Absolutely!
My two cents,
Phil
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08-29-2013, 11:54 AM
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Join Date: Nov 2009
Location: San Francisco, CA
Posts: 351
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Bridgeport
I second Bob's experience on the Bridgeport Series I CNC converted to use something more recent for control (EMC in my case.) The machines themselves are inexpensive, and usually did not get much use because the original controls were so poor.
Sorry, saw the Tormach reference as well. In my experience, which is probably ~25-30 hours on the machine, I'd never invest in one, and buy a used BP instead. The Tormach has a puny little spindle motor, and cannot cut at reasonable rates. The stepper motor approach makes it cheap, but it also makes it run very loud, and on nice curved parts it gives you a crummy surface finish.
__________________
Kevin R. Walsh
Cozy Mk-IV
Last edited by krwalsh : 08-29-2013 at 02:13 PM.
Reason: Added info
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08-29-2013, 11:59 AM
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Join Date: Jun 2006
Location: 8I3
Posts: 3,564
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Tormach's target is entry level and from what I've seen they have very nice machines that run Mach3.
I have been using Solidworks since 97 so I'm pretty good with it, a college friend is a reseller so I get evaluation copies. For me to "evaluate".
I've been using CamBam to generate G-code and for $150 it is the best bargain out there. Simple and just works. Most of my work is 2.5D but I have done a bit of 3D with CamBam by exporting .stl files from SW. It will do both mill and lathe.
For lathe work I have a 90's vintage Emcoturn 320 that I picked up for $1000. A couple of months ago two went for $7K/ea on ebay. Quite a buy 
__________________
Please don't PM me! Email only!
Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
Last edited by rocketbob : 08-29-2013 at 12:05 PM.
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08-29-2013, 12:39 PM
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Join Date: Jan 2005
Location: Near Scipio, in Southern Indiana
Posts: 1,779
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No real idea why you are approaching this, but will throw out my thoughts. I, too, wanted to get into CNC. I didn't want to be able to make large items, but wanted to learn the process, and the software. I settled on a Taig desktop unit, and am happy with my choice as it did what I wanted--it taught me how CNC works. More accurately, it is teaching me...
6" X 12" isn't big, but I am amazed at what I can produce. The Taig is quite accurate and affordable. I have about $2K in the whole setup. Personally, if you want something that can be up and running in short order, I would look at one. It does beautiful work. Just not big stuff.
Bob
__________________
Bob Kelly, Scipio, Indiana
Tech Counselor
Founder, Eagle's Nest Projects
President, AviationNation, Inc
RV-9A N908BL, Flying
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08-29-2013, 02:05 PM
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Join Date: Sep 2012
Location: 07TS
Posts: 472
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Let me throw out another option, actually for anyone that might be interested.
I teach a high school engineering program ( www.pltw.org). As part of a grant from our local city I have been able to put together a really nice machine shop/prototype lab.
The cornerstone of the lab is a Haas 4-axis Mini Mill 2. We haven't had the equipment setup for very long, and we are still just learning to use it (students, and myself).
I would be quite interested in helping machine parts for anyone that is interested (I also have a Fortus 250mc for rapid prototyping). We are just learning MasterCAM, but if you can supply me with GCode, I think we can make the part for you.
Just keep in mind this is a high school program, and we are still learning.
-Dan
__________________
Dan Weyant
RV-9A N96KD
Done and Flying 4/30/2015
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