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CNC Milling Machines

mculver

Well Known Member
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
 
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.
 
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
 
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
 
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.
 
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-milling-accessories.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
 
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.
 
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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 :)
 
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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
 
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
 
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

Gee, Dan, haven't you heard of 3-D printers? They seem to be everywhere. Just design a part, and it magically appears, almost like in Star Trek.

You are to be applauded for teaching that things can still be fabricated by tried and true methods, and that the mind still has a part in the manufacturing process. I don't think anyone wants to go back to when things were all hand made, and adding the computer to the build process was a big step forward. Removing man totally from the equation, however, is a mistake, at least in the learning process. PLTW is wonderful, but I hate to see only 3-D printers as the only actual fabricating machine. Machining could become a dying art form.

Bob
 
Gee, Dan, haven't you heard of 3-D printers? They seem to be everywhere. Just design a part, and it magically appears, almost like in Star Trek.

You are to be applauded for teaching that things can still be fabricated by tried and true methods, and that the mind still has a part in the manufacturing process. I don't think anyone wants to go back to when things were all hand made, and adding the computer to the build process was a big step forward. Removing man totally from the equation, however, is a mistake, at least in the learning process. PLTW is wonderful, but I hate to see only 3-D printers as the only actual fabricating machine. Machining could become a dying art form.

Bob

Bob,

We have and use quite a bit a 3D printer (Fortus 250). It is a wonderful tool, and we help fund the program's scholarship fund by doing quick turn parts for local businesses.

However, you are correct. Machining is becoming a lost art form. So much so that I was able to convince the cities economic development council to foot the bill for the equipment to train the kids. We have a ton of local businesses that are just begging to get employees that even have the very basics of machining.

Of course if I can make a few parts for my RV-9 in the process, all the better :D.

-Dan
 
Gee, Dan, haven't you heard of 3-D printers? They seem to be everywhere. Just design a part, and it magically appears, almost like in Star Trek.

Bob

Funny you mention Star Trek. The first 3D printer I ever saw was about 20 years ago. I was at a job interview for a company that made them. They wanted me to redesign the user interface.

If I remember correctly the machines cost in the $750,000+ range, but holly cow! I couldn't believe the technology. I went home and told my wife that they build the Star Trek replicator, just a bit slower :).

-Dan
 
Maybe look for a used machine

Maybe you can look for a used machine? I dont know what the converted machines are selling for, but we bought a used HAAS VF2 a couple years ago for about 10K.

It was a tremendous increase in quality over a converted machine.

We dont use it for serious production work, but it has been my go to machine for little toy projects since it is easy to setup. It is kind of slow, but definitely will get the job done!!!

I found it on Craigslist of all places...

Well, I just looked at the example you posted and am going to guess you are not real anxious to spend 10k on this. Sorry!! I should have looked at your example first.
 
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CNC Machining

About ten years ago while working in England I purchased a non working Shizuoka cnc bed mill ( slightly bigger table and travels than a Bridgeport)and shipped it home to Southern New Zealand
It ran stepper motors and I converted it to PC operation running Dolphin cad/cam software.
Starting out with a non working allready converted cnc machine that has ball screws on it travels is a big advantage over a fresh conversion
It allows 'climb milling' that provides a better finish and lower tool wear compared to 'conventional' milling. Without ball screws (They have no back-lash) the tool will bite in due to the direction of tool rotation.
I'm building a RV-3B (#11465) from bare materials. and use this machine to make the parts that lean towards cnc manufacture.
Re: the discussion on a matched hole RV-3, some drill,cut,and file parts could be on a dvd.- draw them as dxf files, and this would allow builders with either a cnc router or mill to quickly make parts very accurately.
If manufacturers of radios and parts supplied dxf files of their cut outs, it may encourage builders to use their products.
I cut a shaped hole for the latest Dynon com radio but had to redraw the dimensions given to provide a machining file. Drawing/coding/checking time about 1 hour.
Machining the panel time- 4 minutes.
About three days ago there was a very good set of pictures and story on the Thatcher CX4 forum. where the builder uses a cnc router to make parts and drill accurate holes for his aircraft.
Certainly has its uses, one of my 'clients thought that once you had the drawing on disc- you just walked round the back of the machine and held out you hands for the parts to fall into!
Neil Robertson
Invercargill
New Zealand
 
I used a homebuilt machine for some work. It isn't super fancy or super expensive, but did what I needed it to do.

002.JPG


007.JPG
 
How about a CNC router instead?

Mike,

I have a converted Sieg X3 in the garage which is the same as the Grizzly. The truth about these machines is that they are not that well built. I know you said you didn't want to hear that - but hear me out - I own one.

The X3 is designed for hand wheels - not CNC. The DC motors and controllers for the spindle are unstable. Having the cutter stop is acceptable with hand wheels. It gets boring by the time you snap your third carbide end mill. They only do 2,000RPM. For aluminium you will want 4,000 RPM at least. The ways are not particularly well finished and the head is difficult to tram.

I have a very nice machine now with ball screws, double ball nuts, new US made motor controller, 4,000 RPM spindle, US made Gecko stepper controller, totally rewired, ways machined etc. It takes time, research, knowledge and money to do it (and I got a head start with a PROMiCA kit). As others have said I might have been better to find something else ready to go. I've enjoyed the journey though.

The other thing you will find is that the machine has a small working envelope. (400mm X 180-200mm Y and 400mm Z). That is pretty big for a hobbyist but not big enough for mass production or large parts. To do instrument panels you need something bigger.

If your heart is set on an X3, can I suggest either the KX3, Syil X4 or one of their bigger models. Either of these machines can be had for around $5,000 in your part of the world at the moment. You will get a head start and when you sell it it will probably be worth something as the buyer will know what it is. Despite how it looks, I can tell you that these machines are cheap compared with a converted X3 and you will be cutting quickly. That said, they are built to a price.

You may be wise to consider some of the other machines people mentioned. However, the X3 style machine will fit in your garage. Some of the others would be great machines, but too big for me.

Something else to consider. You may get better use out of a CNC Router. I just purchased a unit from a CNC company in China. I had been thinking of building a Mechmate for a while, but I could not come close to matching the quality for the price of the Chinese machine. I was able to use the knowledge gained from my research to spec the machine I wanted. The cutting envelope is 4 feet X 8 feet and over 1 foot high. I think that the above probably gives you an idea of my view on converting machines at this point.

Timber is cheap and the software for machining it is more user friendly(Vectric as an example). These machines will cut aluminium if you keep the cutting loads down and use mist coolant. Instrument panels in 0.040 or 0.090 would be no problem, but you will not get as good a result as laser or jet cut as even with a small end mill you can’t make square corners. Sometimes you just have to use a file

For thin aluminium sheet you really need a vacuum table or to sandwich the sheet between some heavier material.

Do not forget that the machine is the cheap part. Then you need software, tooling and materials.

Cheers
 
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Thanks to everyone for their replies. I have been on the road; however was reading them as they were posted.

rwtalbot, I appreciate your feedback in particular. What I was trying to avoid is the tired old "American Vintage" vs. "Asian Innovation" debate. I believe that the market has both, and people are free to choose whichever makes sense for them. Like most religious arguments there is neither a right answer or an end to the argument.

Going to think a bit more. This is a hobby interest, not a commercial one, so tolerances are not as rigorous. Nonetheless like a lot of us I want to get what I pay for. And at the moment I am going to ponder without spending.

Mike
 
Actually, the G0704 is not the same as the Sieg X3. Completely different casting, different head setup, different table. Different machine. Having said that, I don't have either of them. When I looked into getting a mill, the G0704 was a good candidate, but I ended up with a RF45 clone (so far manual, but I'm planning to convert it).

Have a look around on cnczone. There are lots of reports about the G0704. If you are tight in time, there are also conversion kits for the G0704 around. If you search for something like "g0704 bdtools kit" that should give you an entry point for reading a couple of days. Again, I can't offer first hand experience for that mill, I've only read a lot.

I suggest you read some more, make up your mind about what you want to do with it (and "playing in the workshop" is a legitimate answer, I think!), and then decide on the way to achieve this.
 
Wife's new toy

My wife teaches engineering at our local HS, and finally got her new toy set up. We got to play with it a bit today.
IMG_4763-M.jpg

Now I need to learn how to use it to make airplane goodies.
Any suggestions? The students have an opportunity to make things and sell them to sustain the program.
 
A few thoughts

I converted a Harbor Freight mill drill to CNC about 20 years ago, and have found it immensely helpful in aviation projects ever since. I?ve often wondered why this technology hasn?t been more popular in ?RV culture?.

A few thoughts:

1) The software is just as important as the hardware. Modern CAM software has ?high speed machining? or ?waveform? tool path options that really help overcome some of the weaknesses of small machines. These tool paths avoid chatter when the tool is plunging into material or profiling tight inside corners. Consider Autodesk Fusion, Inventor, or Solidworks with the free Autodesk HSM CAM plug-in.

2) CNC machines aren?t exactly ?plug and play?. I use this technology to produce parts more accurately, not to produce parts more quickly. It takes time and effort to develop proficiency in the software and to create a reliable workflow to efficiently process parts. In particular, cutting out sheet metal profiles on a mill requires tricky work holding and careful programming to produce a good part.

3) The make vs buy decision on a mill is just like the make vs buy decision on an RV - if you enjoy the build process, go for it, but expect to spend more time and money than the final machine is worth. If my old mill ever bites the dust, I?ll probably consider an off-the-shelf Tormach. If I had a bigger shop, I?d consider a lightly used HAAS or an old Mori-Seiki MV Junior.

4) In a home shop, slow and steady wins the race. The material removal rate of a home shop mill isn?t going to be very fast. Make light cuts with a small blast of air to clear the chips away. Use of cutting fluids isn?t worth the mess.

Good luck!

Matthew
 
Matthew is dead on. I have a Haas CNC mill and lathe that I run hard two months out of the year, spend a couple days cleaning up the mess, and use only for unprofitable one offs or personal projects like building an airplane the rest of the year :D

You will find learning the software to create the tool paths for the machining much harder than running the machine. Basically, once you get the program right you bolt in blank stock and hit the green button. Leterally, if someone asks me to make one of anything the first one can be $500.00 for illustrative purposes and the next hundred will be $500.00 depending on material costs. These machines are great but not practical unless you need precision to .001" or need to make 100 plus of whatever it is.

This will not play well with most fellows but the bottom end machines are difficult to nearly impossible to operate like the old hand mills and lathes operate. You want to be able to stick something in the machine and make a simple cut without creating a program with your CAD CAM software. To do this easily you need a fifty grand machine, not feasible for building an RV.
 
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