A video about a guy who makes a cnc mill.

[bugler]

In this video a guy makes in minutes a cnc mill. It is rather small and he doesn't show the software to run it.

It would be very interesting to develop a kit to make this home cnc mills so people with ideas can easily develoop them.
I know a guy who has an idea, that in principle seems interesting, to impove bycicles. He has spent years working in the idea and paid some people to manufactures some pieces but somehow they didn't get ir right and this guy hasn't been able to finish a working prototype to test his idea. With this kind of tolols it would be much easier to do.

Any ideas to have a working tool like this one?

YouTube - Easy to build Desktop CNC Mill

[citfta]

CNC mill

Hi bugler, that is a pretty interesting video. I retired from a job where I repaired the electronics on CNC machines of all kinds. What he is showing you is not a true CNC machine because it doesn't have any kind of feed-back sensors that I could see. I believe those were just stepper motors. With only stepper motors you can tell this motor to move so many pulses and that motor to move so many pulses and therefore to some degree program the machine to make some parts. The problem is if anything does not move just as you think it will then you get bad parts. With feed-back the computer can keep track of where everything is and control the acceleration and deceleration of the motors and make sure both or all 3 axis stay in step if you are doing compound cuts. In other words that machine would be great if you are only planning to make straight cuts. It would be very difficult to program it to make a radius cut or to machine a circle because for those kinds of cuts both axis are constantly changing speed. This machine would be pretty good for drilling holes in PC boards or other applications like that. It only has to move X and Y to the correct position and then move Z to make the holes. As long as everything is pretty snug with no backlash or slop this little machine would be pretty good for that. To make it work without feed-back you would need a computer and a program for driving the machine. You also need a driver board for each axis that can take the commands from the computer and convert that into pulses to drive the motors. I hope this info is some help to you.

Carroll

[Jiffycoil]

Cool video Bugler.

@Citfta
Do you know of a good small shop CNC in 6 to 8K range? Oh what I could do with one of those.

[bugler]

Hi bugler, that is a pretty interesting video. I retired from a job where I repaired the electronics on CNC machines of all kinds. ...

Carroll

Thanks for the feedback.

I didn't know the cnc needed feedback. How is the feedback implemented? Can you give details?
A real cnc wold use stepper motors or other kind?

I think it could be good business to sell complete kits (including the feedback mechanism and the software). What do you think?

[sniky]

Search the project on instructible you will find it full instruction there

[wrench76]

sherline cnc

@jiffycoil,and others...
I have a Sherline lathe that works very well.They are small though,max dia. is 4 in. I think .You can get a whole setup mill/lathe w/ servos or steppers. They even have a combo w/computer
Brian

[citfta]

Feed-back

Hi guys or maybe some gals too. There are several methods of providing feed-back on CNC machines. There are linear scales that are mounted on the edge of the moving axis. These have a head that is moving with the axis and a long scale like device that is mounted stationary. As the head moves it reads lines that are etched into the scale part. This info is fed back to the computer to give a very accurate position feed-back. Another method is an encoder that is mounted on the ball-screw or on the end of the motor. This method is fine as long as there is no slop in the ball-screw. Real CNC machines have very precision type ball-screws that use special recirculating balls and spiral grooves to maintain the tightness necessary for precise positioning. I worked on many machines that could hold a precision of 1/2 of a thousandth of an inch.

I don't know about any sources for CNC machines. Someone told me that Harbor Freight had one but I haven't had time to check that out. They have stores all over the country so you may have one near you where you could check it out.

Later, Carroll

[Jetijs]

Hi all.
I have built several cnc machines over the years. It is true that motors with feedback (servos) are better, but I have never used them, I use step motors and I haven't had any problems yet at all. Lack of feedback is critical if the cnc machine is under great loads or the motors are too weak, this can result in missing steps and inaccuracies in the machined parts. I can tell you one thing, it is way less expensive to build one by yourself than to buy one commercially. A typical cnc milling machine with a work area of 800x600mm will cost around 5000$, but you can build one yourself for around 1000-1500$. It is not that hard and is lots of fun. If anyone is interested then I would recommend hobbycnc controller boards and motors, rather cheap and reliable, works great. If you need cheap linear rails and ballscrews look for linearmotionbearings on ebay shops, he has great prices. All the tools you need to build a machine is a thread making tool, a drillpress, and a band saw. I can post pictures if you like.

[Jiffycoil]

I would love to see pictures. I think I might be handy enough to build my own.

[Jetijs]

You sure could make one on your own, it is not a rocket science
This is my first machine made out of plywood and ordinary threaded rod as a lead screw:




It worked well but was way too inaccurate and slow for my needs, also I wanted to cut metal, that means liquid cooling and plywood wont cut it. That is why I made the second machine:



This worked a lot better and I am using it, but the steel rods that are used as the guide rails are not supported and that makes it hard to use larger diameter end mill bits as they tend to bore in the material and bend the steel rods just a bit, this causes vibration and any vibration will break any endmill bit in any material. That is why I made the third machine using supported linear rails and ballscrews that don't have any backlash:




This last one works very well.
I make almost all the parts for my research devices with these machines, it sure makes building prototypes easy. Here are just some pictures of all the wonderful things you can cur using such a machine:









If I can help, just ask.
Thanks,
Jetijs

[citfta]

I stand corrected by the master

Hi Jetijs, I am glad to see there is software that can run stepper motors that accurately. I stand corrected by your expert advice. Thanks for the great links. My son has a couple of Bridgeport type mills and a couple of lathes. It would be great to convert at least one of the mills to CNC. At least my advice about needing good ballscrews was correct. Some information for any new people to this forum Jetijs is considered as one of the best machinists if not the best on this forum. If he says it can be done you can count on it. Thanks Jetijs for correcting my mistaken thoughts and for giving good advice.

Carroll

[Jetijs]

Thanks Carroll
I did not mean that you are incorrect, you are still right about that the servos with encoder are the way to go for high precision and heavy duty machines. If I could afford I would use servos, but they are moire expensive and so far I did not have any problems with steppers. I machine only soft metals like brass, copper and aluminum, also wood and plastics. those materials do not make a great load on the step motors so no problems with lost steps
Have a good day!
Jetijs

[Jiffycoil]

OMG that is beautiful. I really need to look into building something like that. Thanks for the pictures