Is CNC the solution for me?

[Ryan]

I posted to HMEM about three years ago, asking about having parts manufactured by a professional shop. The consensus was that it was going to be too expensive.

Does anyone here build entire engines solely on a a converted/ somewhat affordable CNC mill?

I've talked to some people about and they say that they spend 80% of the time setting up work and the rest actual cutting. Would a fourth axis or even 5 reduce the setup time significantly? other additions like a power drawbar and toolrack to facilitate auto tool change would help

not even going to think about which machine yet. just wondering about the feasibility. I have people to help me physically, but any automation, I am guessing would reduce the skills and time my 'assistant' will need to move the workplace?

how about an industrial robot? just kidding...

other options I have thought:
1. Buy machined kits, build with assistant (this needs to be done with the CNC option too) - horrendously expensive.
2. Buy old engines in need of restoration - probably still expensive/ and not easy to come by the lucky bargain ?
3. buy completed engines - not really that satisfying

 

[Tin Falcon]

First of all Ryan where are you in this hobby? I expect a total newbie.

Before considering investing in cnc read as many machining books as you can learn the basic machining operations. Read here.


The second question is what is your goal. Learn machining ? Build a CNC machine ? Assemble an engine collection. Learn about steam engines.

I think people here that have a cnc mill also have and use a lathe to build engines.

If you want to learn to machine and build an engine start with a manual lathe. You can build an engine on just a lathe.

You can build an engine with just a mill as well.



Adding a fourth axis with allow for more complex parts and operations not sure it would reduce set up time.


In a production shop tool changers save time changing tools but in a home shop an expensive addition to a cnc machine.

In a production shop typically you have one or two highly skilled people to set up and program several cnc machines and then less skilled folks to operate.

In a home shop you need to be skilled in ALL aspects of shop operations. YOU are the manager, the set up guy, the operator, the purchasing agent , the safety director, the maintenance tech, the QC department ,accounting ......and the apprentice that sweeps the floor and is expected to constantly learn more.

If you want to start an engine collection but lack the skills and machines to build there are affordable pre machined engines you can buy . you just assemble them and paint if you wish. There are nice kits for $100- $140 a lot cheaper than a cnc machine.
Tin

 

[Tin Falcon]

Ryan I went back and read some of your posts and see you have a small lathe and mill.

Learn to use what you have . Make some simple model engines.
Patience and perseverance are as much a skill in this hobby as cutting metal.

CNC can enhance the home shop it can allow work that is very difficult if not impossible to do manually it can make bolt circles and curves easier without a rotary table. It is a different way of machining.
the new fangled mill wizards makes programming relatively easy for the mill.
Tin

 

[Septic]

I agree with Tin Falcon.

I think you'd be missing out on a huge amount of first hand knowledge and useful experience if you don't take the time to understand just how much you can do with even very basic equipment.... Plus..... Every good CNC machinist I've ever known was a good manual machinist first...

I can only speak for myself, but I've found that the necessity to find solutions for awkward problems has made it so much easier for me to produce the parts I need and unless I found myself in a position where I needed to produce huge numbers of identical parts, I would never consider CNC

It's quite possible to build a surprisingly impressive engine using nothing more than a decent bench drill and a few hand tools, so imagine what you can do with a small lathe and a mill....

 

[Dave Sohlstrom]

As others have said CNC is nice to have if you are well versed in manual machining. If you are doing one off parts then CNC only works well for parts that would be impossible or very difficult to do on a manual mill or lathe.
A case in point. I am building a boring/facing head for my lathe. It needs a star wheel that engages a pin every time the head comes around to advance the cut .005".
The plans give the information needed to make the part on a milling machine. Because I have a small CNC mill I did the Gcode and finished the part in the CNC mill.
It took a couple of hours to get the part ready for the CNC then it took only 15 minutes to cut the star.
It would of taken another couple of hours to do the star in a manual mill and lots of file work.
Where CNC shines is if you have lots of the same part to make and the time to make the part blanks is minimal.

Dave

 

[kvom]

I have a CNC mill as well as a manual mill. The CNC mill is used whenever one of the following factors occurs:

1) The part has a profile or pocket with any angle other than 90 degrees or has a rounded path.
2) I am using a very small diameter endmill and need precise control of feedrate to avoid breaking the tool
3) I need engraving
4) The part requires soft jaws to hold it
5) I need a hole whose diameter is larger than my largest drill bit
6) I want to make multiples and they can be done faster

I use the manual mill:

1) for reducing stock to size or squaring
2) Most drilling
3) Anytime I need the rotab mounted horizontally
4) Any time I need the larger table
5) And generally, whenever I think work can be done faster

 

[Tin Falcon]

CNC is not a magic bullet for the hobbyist. Many here have purchased cnc or retrofitted a a mill. A few have started the hobby with cnc.

Another are where cnc can be helpful is if you have limited shop time but can do the prep work and programming at another location.

If you have had cnc training at work or in college then that will help if you can take a college class do it.

Also do not be afraid to learn to make fixtures and jigs these can save time and materials in the long run both with manual and cnc.

You can learn speeds and feed from a book. And you can learn some work holding a lot of work holding you need to learn by doing.
Tin

 

[rodw]

I think it depends on if you like doing things or planning things. I like doing things and spend enough time in front of a computer at work. For me, I don't need to think about CNC. I have focused on acquiring the tooling so I can get most things done. I think I will be happy once I get DRO's on both my lathe and mill. For me, there is a huge learning curve with 3D design and I'd rather be in the shed. A friend in my street has $10k in CNC software and a small CNC mill and a CNC lathe he built himself. If I was 30 years younger, I think I would be right in there learning it as I think there must be an awesome career out there as a 3D/CNC designer.

 

[kvom]

3D design and milling is another step beyond what I do with my mill. 2.5D milling just means that the CNC mill does what you could do on a manual mill if you have 3 hands and were very precise. The CAD drawings I make are 2D and essentially identical to the paper 2D plans we typically use.

 

[Ryan]

Thanks for all the quick replies.

I just realised I didn't mention what sort of disability I have. I noticed this forum about machining with disabilities and thought it was a great idea to share various thoughts about adapting the process to suit various disabilities. I'm about as physically disabled as you can get, this is why I use a computer for pretty much everything (I'm doing a bachelor of arts, so reading, research, writing) because I can use a mouse only. I'm writing this using voice recognition software because I can't physically type. I think I would go crazy without computers.

I'm a bit of a weird arts student because I also love anything technology related, and I have a certificate in information technology.

I find CNC machines fascinating and love watching videos of them doing their thing, but I'm not sure I would want to design or build one. I'd like to build a few different stationery steam engines (mainly because I like the aesthetic of them and the links to the industrial revolution) but also have a number of other ideas for projects including parts I need for the wheelchair and various other equipment - perhaps the hardware components of robotics.

The CAD side of things is not a problem because I have used 3-D modelling software extensively (for more artistic stuff) including some gadgets in CAD software. I am used to thinking in a 3-D space.

One of my personal carers has a background in woodworking so we build some projects (I do the design, he does the physical stuff). I plan to also employ another helper so I will have more time to work on projects. My dad owns the lathe it's a BV20C with a combined mill (the mill component is not working, and I haven't found any detailed information about it). We intend to
make an adapter plate for a 125mm independent 4-jaw and add a QCTP, but because of the lack of documentation I don't know about compatibility.

I can't use a manual machine at all and it would be totally pointless learning about and teaching manual machining to my carer. But the point Tin Falcon made "Another are where cnc can be helpful is if you have limited shop time but can do the prep work and programming at another location." I don't have a lot of a shop time, so if the only assistance I need is to clamp work, then I myself can in theory 'drive' the machine via Mach3 (most likely). I have all the time in the world to do the setup on the computer, just not so many hours of personal care available.

Does CNC mean if you have the design, you have the g-code worked out and you have squared the stock then you home the machine and start the program, but blue dying and laying out the holes and parts to be machined is not necessary? That should save some time.

Essentially I'm looking at the feasibility of CNC, not for its repeatability of multiple parts, but for its connection to a computer and thus its accessibility. Can you jog the axes via mach3 so you can essentially machine as if you were doing it manually (sounds counterintuitive but it would allow me to 'manually' machine potentially).

Also if you have three axes and you need to machine six sides of a rectangle that means you have to clamp and home the workpiece 6 times, with 4 axes you need to do that three times, 5 axes would be twice?

 

[rcfreak177]

Ryan,

Seems the manual side of things are out of the question you may want to have a look at this trial for DeskProto cnc
http://www.deskproto.com/download/trialversion.htm
This will give you a great insight into how it all works (from what I gather you have a good idea already, (Bonus))

It is easy to use but the downside you will need a cad program to do the drawings externally. I find it is easy to use and reasonably priced.


As far as cnc milling machines, well the prices can be very intimidating.
There are several options on the market see below.

Tormach PCNC 770
In my opinion the Tormach is the best.
http://www.tormach.com/product_pcnc_770_main.html
This machine also has an optional cadcam software package at a discounted rate

Syil X4.
http://www.syilamerica.com/machine_x4st.php
Syil also does a small cnc lathe

Sieg KX1.
http://www.siegind.com/products_det...=comp-FrontProducts_list01-1325833166395.html
This is a smaller machine than the 2 above

There are several others out there but these 3 are the most common, All 3 run from an external PC running the Mach 3 cnc control software.
Unfortunately there is no cheap way out of cnc machines, then you need to add tooling on top.

Obviously there is the second hand market where you sometimes can find a bargain.

As far as setting up the machine, yep you are right, do the drawing and Gcode inside the house,
* Load the Gcode to the machine PC
* Home the machine
* Set up the stock
* Set the work and tool offsets
* Press Start and enjoy
* Obviously your helper can change the tools for you as required

No need for marking out etc.

All the best mate, any questions just fire away.

Baz.
.

 

[Tin Falcon]

Ryan :
I did notice this thread was in the machining with disabilities. And the need of an assistant . I missed the you being disabled part.

You have to follow your dreams. I think people here will be able to identify obstacles and help you overcome.

As far as clamping things in there are many pneumatic and battery powered tools available to assist.
You understand CAD. CNC is the G code machine end of things.

there are several ways of getting to G code

program line by line

conversational programming such as the new Mach wizards for mill.

CAM takes a drawing and converts to G -code needs input from a human.
IMHO conversational programming is the way to go for most apps .

You will probably need to have a tool changer .



You may want to look into a trunion for a 4th axis as you will have full access to three sided of the part and limited access to two more.
so watch videos. Dream. Buy a couple of PM research pre-machined kits to get an idea of what it takes to assemble an engine.
Tin

 

[Ryan]

Is it a big deal to turn the part to machine on the other side and set the offsets accurately? I have seen videos of that being done with a DTI which looked like a real hassle.

I wonder with a forth axis you could mill turn cylindrical parts with sufficient accuracy for model engine pistons & sleeves for example?

 

[Ryan]

No worries Tin. I have seen some of those PM research kits. They look pretty good. another one I have been checking out is Cotswold Perseus kit.

 

[Rivergypsy]

I'm not sure about Mach3, but all the CNCs I've used have been joggable. What can take some getting used to is the lack of 'feel' with a CNC handwheel compared to a manual machine, but at least you've not got that hurdle to overcome.

If you have 3 axis, then each face worked will need to be a separate op, but with both 4 and 5 axis, you can hit a minimum of 3 faces in each op, so a lot of parts can be finished in two ops, with a flip and 180deg rotation between them.

 

[kvom]

Yes, if you have the g-code loaded and the stock mounted in the vise or clamped elsewhere, then you just need to zero the tool in 3 axes and click the green button. Unless you have a tool changer then tools must be changed manually. Zeroing in my case is done with an edge finder for X and Y, and a height setter or gauge block for Z. So the edge finder is essentially a tool change. If your tools are all in holders, their heights can be measured once and stored in mach, so that you only need to zero the first tool to the stock to obtain a global offset for the rest.

You can machine "manually" with mach3 but that involves typing g-code commands into the MDI (manual data interchange) screen. Using jogging for this would not be very practical since each mouse click would move the tool a specified distance, than stop. You can use the arrow keys to move the tool, but that uses the rapids feed rate. If you are unable to type then such manual machining would be difficult.

 

[canadianhorsepower]

You can machine "manually" with mach3 but that involves typing g-code commands into the MDI (manual data interchange) screen. Using jogging for this would not be very practical since each mouse click would move the tool a specified distance, than stop. You can use the arrow keys to move the tool, but that uses the rapids feed rate

I think their is a few more thing to add here. I use the jog pad (tab on key board see picture) very often to resurface my parts I simply keep my finger on the button and there it goes.
There is also a calibration with 3 different setting that you chose
on one of those setting I'm only going .001 per click

 

[Septic]

An ha!.... The mist clears...

Being disabled myself (although less severely than you) I misunderstood your needs Ryan.

I wonder whether one of the newer (and now much cheaper) 3D prototyping printers and something like a 40W laser printer/cutter/plotter setup might be a good way to start, being as the assistance you require will be far less than that needed for a full CNC machining setup. It would at least allow you the opportunity to produce intricate, complicated and useful items from engineering plastics with comparatively little initial outlay and the means by which to recover a large portion of that expense should you ever find that you wish to try something else, simply by re-selling the equipment on fleabay?

 

[Ryan]

No problems septic. I had thought about a 3-D printer but can't think of much I would like to build in plastic. I prefer metal. There isn't enough metal. One of those sintered laser deposition machines that can print metal would be good except, $500k is slightly over my budget

 

[Tin Falcon]

Ryan : A couple thoughts


First of all tell us where you are there may be people from this forum that could assist you.
Also there may be organizations that can help you get set up.

You seem to thinking mill only. Why?

A CNC mill will cost a few grand Like 3-10 add quick change tooling and a tool changer and general tooling the price can double.


I probably have $2500 -$ 3000 in my home built mini mill. a guess.

But my cnc lathe only cost $300 to put together.
It uses the same computer, controller software etc.
And a pallet tool holder easy easy and cheap to add.

if you are going to do the cnc thing do not rule out a lathe.

Tin