CNC files

[alan2525]

One area where cnc really excels is repeatability, often in model engineering jobs you have to make multiples of the same part. I find that really soul destroying as I'll happily make one part but it's one reason I don't model 17th century galleons...on account of all of those guns!

I think the affordability of cnc machines can only encourage people into the hobby, plus the cnc machine won't do everything for you! There's still a whole range of skills and additional processes that need to be carried out often manually.

More Beers?

 

[DICKEYBIRD]

John S makes some very good points. I can relate to the statement about CNC becoming a hobby in itself.

My life-long hobby/affliction/obsession (until starting this machining thing) was designing & building r/c model aircraft. I began using CAD to enable me to generate a clean & clear plan to share my stuff with others of like mind. Then I saw a magazine article about home-built CNC and built a myself a CNC router. Once the learning curve (which was very steep 10-12 yrs ago) was over, I looked for excuses to make EVERYTHING on the router. Many parts could've been made a lot quicker the "old way" but I chose to use CNC if at all possible. There's something extremely rewarding about being the master of a robotic device that does your bidding and can make things with extreme accuracy and repeatability. I found myself completely absorbed in the process of CAD/CNC creation of my parts and enjoyed every minute of it.

I don't use it as much now since I've pretty well dropped out of the aircraft hobby while learning to machine metal. I have used it to spot & mark hole patterns for machining projects since it's positioning is very accurate. It's made from MDO plywood and uses drawer sides so is useless for cutting anything other than balsa and thin plywood or plastics.

I read the X3 conversion threads on CNCZone with mouth open and drool running out. Unfortunately, my very limited budget is soaked up adding tooling now & then to my shop. I'd do it in a heartbeat if the funds were available. Sigh, someday.

You guys that can afford it should go for it; you won't be sorry! ;D

 

[alan2525]

When cutting parts out with a cnc machine I really enjoy the feeling of getting something for nothing and enjoying a cup of tea and an episode of Eastenders (OK maybe enyoy was too strong a word) whilst my machine plays it's little stepper motor concophony as it cuts away - then checking in on the machine to see the cutter back in the home position and a little assortment of completely professionally finished parts awaiting assembly.

The alternative is to see the shank of the cutter and a assortment of partially cut out parts and the cutter conviniently next to a hold down after setting the clearance to 2 mm rather than 12 mm!

I also like the fact that once the part is drawn it removes some of the worry about messing a bit up if the part had a huge number of man hours work into it. It's nice to know it's easy to change the design and adapt it to suit and easily cut it out again.

I also like the fact that I can switch my work light off and close the door whilst the machine makes parts for me.

 

[shred]

Back to the mill, If you want to take advantage of a CNC mill you really need a good CAM package. What we use at work is just a simple 2-1/2 axis package. This would not work well for what a lot of us would like to do. I do think software has and is continuing to come down though. If you want to take full advantage of a CNC mill you would want to do 3D milling I think.

2.5D will do fine for 90+% of what a CNC does.. 3-D (and 4th Axis) are nice, but not really necessary for a whole ton of stuff. I thought I would use 3D a whole lot more than I do, which is rarely.

 

[Julian]

Hi All,

My next two projects for "Tooling" are to make my xi into 3 or 4 axis cnc and to build a dedicated cnc machine from scratch. The first because my hand aches turning the handles and how many times have you turned it the wrong way and had to start again!!!!!! The second machine is because it is a challenge and why not? I'm still building something I either want or need or both. Whether anyone likes it or not cnc is here to stay, grow and become the norm. An example...... how many complained when the electric lathes threatened to take over from the peddle or belt driven. I bet they said "Thats cheating and it will not last!!!"

Look at it this way....does it matter how you make the parts you want? Not to me it doesn't...bring on the cnc.

Julian.

 

[Alphawolf45]

Look at it this way....does it matter how you make the parts you want? Not to me it doesn't...bring on the cnc.

Julian.

.
.It does certainly matter how you make the parts, this isnt really about the parts is it?..If it were just about the parts I'd have some one of these experts build my parts and save me the bother...No this is about having your own machinery and enjoying the using of that machinery...And naturally the choice of machinery is beauty in the eye of the beholder..Its your choice... I'll take one of each if I get my druthers , I like'em all- dont you?...... ;D

 

[Julian]

.
...No this is about having your own machinery and enjoying the using of that machinery...And naturally the choice of machinery is beauty in the eye of the beholder..

But if you have build that machinery to make the part wheres the problem. I don't beleive it matters where the part comes from. If you've made it yourself by ANY method with ANY machine....fine. If for some reason you can't or don't want to make that part......buy it. Thats fine too because thats your choice. If you bought all the parts ready machined as in a Stuart model or one of the 2" or bigger kits.......so what? you've still built something. As far as I am concerned it does not matter how much one makes or buys ready-made its the "doing it" that gives this hobby its variety and appeal.

I am NOT having a go at anybody here but accept that CNC is moving in fast and then whatever follows it!!!I say "Bring it on. If it helps me I'll buy it or make it". I am gonna build a cnc machine to use in my shop. Is this different from making any other tooling for the shop? NO!!! Trust me we need guys like John to help the developement of this type of product. Don't knock it...use it.




Julian.

 

[alan2525]

Well said that man!

CNC is just a very useful tool, it's an extension of having a digital readout on a mill, the machine just rotates the hand wheels like a very elaborate power feed!

The world of machining has always been about striving for accuracy and machine tools have been invented to make the job easier, more accurate and also faster to produce. I don't think it undermines a model, however it's been created.

 

[John S]

HOW you make parts does matter depending on your view on the model, your leisure time, personal build up, experience and the knowledge and ability to learn.

If anyone expects that they can go out and build or buy a machine load a code and it spits a perfect part out is in for a shock.

Just as when you were first let loose on a lathe you didn't do an internal multi start thread did you ?
Chances are the first few threads you did were crap - mine were

Just as making a run of parts on a turret or capstan lathe will differ in setup and operation from making 10 one off on a centre lathe so will learning to operate a CNC.

For a start a lot of the important work on a CNC is done away from the machine [ hint extra play time whilst inside with her indoors ] For some this becomes an extension of their hobby. Speeds and feeds are very important, there is no 'feel' on a CNC so you have to understand this more so than working manually.
We should be able to understand feeds and speeds as it is but like many you can get away with 'feel' and sticking your tongue out the side of your mouth makes up for a lot of short comings .

Then we get onto holding methods, again probably totally alien to how you would do it manually.

Take a crank web, manually you would drill and ream the two shaft holes then using a pin in a rotary table you would mill the radius then reclamp and mill the outer web shape in anything from 3 to 7 settings.

On a CNC the quickest way would be to mount a piece of round bar vertically in an old chuck on the bed. Rough the holes, rough round the outside then finish the outside and the holes in one pass at full depth, climb milling all the way for a smooth cut, then part the slice off in the lathe or even two slices if needed.

The skill is still there but it's a different skill.

I recently made this:-

It's a selector cam out of a racing bike gearbox, can you imagine the amount of jigging and special tools, followers etc needed to make this ? Fine for industry when they were making 1,000's but this was a one off and not even a copy.
Worse it didn't work as required and the second one had a different profile on the last cam to stop it clouting the 4/5 gear.

There was absolutely no difference in the setup between the MKI and the MKII

60 Years ago most home shops had a lathe and possibly a drilling machine - period. When I first got interested in home shop engineering no one I knew had a mill, everything was done on the lathe.
Slowly mills came in to supplement the lathe. CNC's will be no different. They won't take over but will be there to supplement existing tooling.
CNC Mills are very adaptable.

Not got a 1" x 20 tap for that special job and it too lopsided to go in the lathe ? Simple take an old broken 3/8" BSF tap grind all but 1 flute away and you now have a thread mill.
Drop it in the hole, start up, move the the side of the hole and do one circle lifting the tool 1 pitch as it goes round.
Perfect thread in one pass and that tool will do ANY 20 tpi thread it can fit into or even thread the outside of a shaft in one pass.

Want a nice flowing shape for a carburettor body and a form tool will be too wide and chatter if you can grind a nice enough shape ?
Simple bolt you lathe toolpost to the mill bed, stick the carb body in a holder in the spindle and switch on. You now have a CNC vertical turning lathe.
Change the tool for a boring bar sticking vertical and you can form the inside shape to get a uniform wall thickness.

Same part - different skills.

.

 

[Bogstandard]

I am really enjoying this post, it is giving me a lot to think about, and John has dispelled a lot of fears about it, and explained very well the way things are done.

As I have stated before, I am a manual machinist, but have eventually got to go down this route. Thru necessity, not want.

I am just about to start on refitting my workshop, and I would have loved to be able to get a small CNC miller that could just be switched easily from manual to CNC, so allowing me to carry on manual milling whilst learning the art of CNC.
But the 836 machines I am looking at just don't seem to be able to do that. Unless you know different.
So that does limit me at this time to buying an 836 and later getting a dedicated smaller CNC mill, maybe the same size as the Sieg X3.
I am very tight for space, that was the reason for the manual/CNC combination thought. Maybe it is the leadscrew bearing systems that would prevent it being able to be done.

Any thoughts?

John

 

[alan2525]

I downloaded Mach3 and Lazycam today just to have a play and get an idea of what is involved setting up the machine, workflow (IT speak) I actually got it to simulate cutting a couple of rectangles which was something! There's a free trial so might be worth a look if you are thinking of going the cnc route, plus the option of using the machine in 'manual mode'...i.e. just giving it basic commands to operate it.

I've bought a little Taig but haven't picked it up yet!

The software looks like it'll take a little getting used to to avoid the endmill from crashing straight into the table! I'm sure it'll be a bit of a leap of faith taking the first cuts on a cnc! Also I think why they use matrix plates a lot on cnc converted machine, just to save or hide lots of "oops's" on the table!

 

[John S]

Again two schools of thought.

Now I don't want to put words into peoples minds or thoughts but get them to think for themselves.
There will be some people for whom CNC will never fit if hell froze over, not because they won't adapt but because CNC won't fit their needs.

At some of the shows and even a couple of clubs I have given talks on CNC, The nuts and volts so to speak. Just out lining the facts as it's too deep a subject to get into in an hour or so.

In this talk and I won't go into it too deep here I identify 8 reasons to adopt CNC. There are more than 8 but that covers the main points. Starting off with lack of trained people given there have been no apprenticeship schemes for the last 20 years to speak off, computer literate people coming into the hobby from office and clerical jobs, ease of setups like that cam, the workshop supporting another hobby like restoring vintage vehicles up to CNC now becoming a hobby in itself.

They I say it's like the pools take any 3 from 8 but hardly any two people will take the same 3 reasons.

Anyway to try to get back on track to John's query about manual machining it is possible to keep some of the manual machining features on the X and Y axis by fitting double ended stepper motors and handwheels but it's usually harder to do the Z axis because the motor has to be mounted either on top or under the column.

Dependant on design and size of machine it's possible to use the CNC'd head or knee as a 'power feed' and the quill as a manual feed.

The other way and eventually many go this route is to use the computer as a glorified all axis power feed.
In many conversions we have been asked to fit handwheels for the manual work. We have explained about using the computer in either MDI mode or conversational, where you fill the blanks in but we still do as they ask.

Later when we ask how they are managing the vast majority say they have removed the handwheels.

Here's a conversational screen:-

It contains simple everyday machining operations that can be done by filling the boxes in and it automatically writes the code.

Things like bolt circles, cut circle, cut arc, pocket circle and rectangle, in fact most modules that make up common shapes and they can be added together.

The next screen take you to the box filling bit:-

This is the material surfacing screen where it works out prepping a block up for machining.

Circular groove for trepanning or 'O' rings.

These are done at the control and only take a few moments to fill the boxes in, when you Post Code it then goes back to the main controller and the code has pre preloaded ready to run given the right tool and location.

.

 

[zeusrekning]

I would say go with the handwheels. At work our CNC's have the handwheels, MPG's,. I often use this to do "manual machining" on the CNC. It is often that do don't want to make a program for something simple. EX. flycutting, machining a step in jaws, drilling a hole.
Tim

 

[shred]

FWIW, a good deal on a manual Taig mill just crossed my path and it's going to go right next to the CNC Taig for those manual jobs I used to do on that.

It's possible to drive the CNC in manual mode, but this is nicer

 

[rake60]

I am also enjoying this thread.
I admire the accomplishments of home machinists who are capable of converting
small machines to CNC.

John S wrote:

There will be some people for whom CNC will never fit if hell froze over,

I'm afraid that would be me.
Please allow me to offer an explanation as to why.
Today at work I set up a job in the CNC machine I operate.
It's a ring with a critical ID, OD and dovetail groove that also has a critical
tolerance. Each side of the part has a total cycle time of 29 minutes.
There are 124 forged rings on the stock pallet to be machined into those rings.
It's a job perfectly suited to a CNC operation.
After 11 hours a day of simply maintining an operation by adjusting tool offsets
as the tooling wears and hydraulic temperatures fluctuate, it's the last thing I'd
want to do at home.

Please don't take that as a negative comment.
It's just my personal view, tainted by far too many hours spent
trying to trick a Mazatrol program into doing what it needs to do.

Rick

 

[shred]

My trick is to completely ignore tool offsets and cutter comp and all that for the time being. Makes things much simpler on a little machine.

 

[Brass_Machine]

I am going to be going to CNC probably very soon. I am playing around with what I want to use for software... I haven't really decided yet. My lathe will probably get the CNC treatment first, followed by X3 or IH mill. I will keep the X2 manual. I have a deal to get some 80/20 extrusions to build a router as well (just need to get off my @$$ and tell him what I want).

I am OFC, doing this for a completely different reason than the hobby of engine building. I am trying to get a business started... I can handle making the parts manually for a little while, but it will get to the point where I need the CNC. May end up buying a second larger lather to CNC

 

[Alphawolf45]

I have 2 cnc mills..One is old Acroloc , weighs 5000 pounds , retains its old controller - not fun inputting programs one line at a time but has automatic toolchanger and can still do the job....
.
But I also have an old Hurco cnc mill, weighs 4000 pounds, I replaced the servo drives and computer and VFD , power supply and limit switchs..Runs Mach3 on a PC...Real good machine..
.
And I have a 5700lb Miyano cnc lathe that I bought with dead controller for 500 bucks...I'll have about 3K in it by time its making chips.
.
I'm willing to discuss pros and cons of buying / rebuilding old cncs...I rather go that route than to CNC a manual machine but there are significant disadvantages as well.
.
And I second the sentiments expressed by rake60...I hate it when I have to run a cnc for hours on end.majorly boring....I prefer to be doing oneoffs with manual mill......A cnc has some 'cool factor' but it dont give me the warm fuzzies like a ton and a half of old American iron...

 

[John S]

.
I'm willing to discuss pros and cons of buying / rebuilding old cncs...I rather go that route than to CNC a manual machine but there are significant disadvantages as well.
.

Very good advise on machines of a certain size.
I often get asked what will it take to convert my Bridgeport to CNC ? The flat answer is forget it.

On one hand you have a manual machine with a worth of say $1,500 to $4,000 taking a broad out look.
You then need to but 3 motors at $150 to $200 each. A set of three ballscrews at probably $600 to $800. Harder still you have to drive a quill that wasn't designed for it and put up with leverage and unsupported forces.
Add to this drivers, transformers, case, switches etc, etc and that adds about $500 to the plot.

So add that up and on a base machine of $1,500 it comes to about $3,400 and on the better machine, $5,900

Only problem is you have now got a hybrid worth about $500 to $800 max.

The best bet is to keep the Bridgy as a manual machine if you have the space and buy a dead CNC. If you don't have the space think about selling the Bridgy to finance a dead CNC and you should be able to do the conversion with money left over.

The old Bridgeport BOSS 1's to 5's are ideal for this. Every college and school had then and many still exist stuck in corners somewhere. The iron is still good, in fact most of these did very little work as the electronic of the day were naff and they blew up at regular intervals.

These had a quill designed for motor drive, a rigid ram, ballscrews fitted to all axis, pressure oiling, fitted motors and cases full of useful gubbins.

When we get onto the smaller machines this same example doesn't apply as there is a very limited source of CNC ready small machines. In the UK there are the Boxford and Denford training CNC, again with obsolete software but even broken they fetch far more than they are really worth on Ebay so as a costing exercise there isn't much difference in taking a Chinese mill, treating it like a donor and converting it.

Often you can be in front as you will be using the latest new steppers which are far superior to the old round ones. Another plus is you can often squeeze greater travels out of a conversion than a design that was written in stone.

.

 

[Cedge]

John S
Your thread has had me doing a bit of looking around at home built CNC. I'm pleased to see controller and stepper kits have come down in price to a level that is becoming attractive. The CNC Router idea has merit for many of the types of things I'd be wanting to do.

I also have a perfectly usable mini-mill that was recently replaced with a larger mill, which might be a candidate for the conversion route. Any particular suggestions for a dependable but economical source for the hardware/ software... etc? Would one be looking for 2.5, axis 3 axis, 4 axis, extra outputs.... for doing things like cylinders or shaping engine bases?

Guidance....?

Steve