RC India

Hello friends...

Have been thinking of writing about this since I started this project, but decided to wait till I was sure that I would be able to complete it.

I am making a 3-Axis CNC drilling & milling machine that can be used for PCB (Printed Circuit Board) drilling and milling and also for woodworking. Future plan is to be able to make rc aircraft parts (foam & balsa).

Total project cost should be around  :Rs: 50,000/-.

The MDF board will be cut to proper sizes and used to make the structure of the machine. There is a fair amount of original work but the structure is mainly a result of careful compilation of amateur CNC machine models build before.

The controller board is based on dsPIC33EP512MU810 (16-bit microcontroller) and the motor driver boards are based on L298 (to be upgraded to DRV8432 in future). The boards have been designed and fabricated by me.

The working bed of the machine with be about 400mm x 1000mm.

The machine can take G codes as with commercially available CNC machines.

A GUI will be developed for pc in which one can load the G code file of a particular design. The GUI will do the remaining work of sending the codes to the controller board.

An image of the CAD model of the machine is attached.

best of luck nairitb remember our little chat about it a long time ago.

Thanks nitesh. Project should be complete by mid-July. Started it on 8 February 2014.

Servo Motors are huge, what size are they? are you using ball screw?

They are Stepper motors. NEMA23. Ya I am using Ball Screw.

Y-Axis Ball Screw coupled with stepper motor. (back side)

Looks great!
All the best

MDF is good but after sometime you will start seeing bend/curve in them. Then i would suggest you to move to Aluminum frame After sometime, that is much better.

Just a small note: while cutting the spindle makes lot of sound and vibration.

@nairitb i had also started a month back and in process of procurement. Since monthly cap of  :Rs: 10k max, so just imported ball screw uptill now, how much ball screw cost to you anyways and how much those motors, i believe you are also importing. Can you provide me your link from where you had purchased motors i am planning to purchase it this month.

Thanks Girish.

@Satya. Thanks for the suggestions. I was initially thinking of using aluminium frame. But price would be much higher than MDF. Moreover, I am doing everything myself - cutting, drilling, fitting etc. So aluminium as a frame would have been troublesome for a loner.

But ultimately I think I would have to make one with aluminium frame in the future  :)

I am not using spindle. Just a plunge router. Black and Decker kw900eka.

Hi Chandra.

Ball screws cost me INR 14,531/- including Customs duty. Imported by FedEx. Bought from China.

Steppers motors also imported from China. Around INR4100 per piece including shipping and Customs Duty. That was when INR-$ rate was hovering around 65INR/$. So it should be lesser than that now. I had them custom made to my specs. Ordered at a factory there through a friend at Aliexpress. So no link. Can give you contact details of the seller if you want.

@nchandra

How much did your Ball screws cost? What the size of your machine?

mine screws are 16mm set of 270,400,900 mm. Paid $135 on ebay with free shipping. I see you are using double nut is it really required.

My sizes are 1280mm, 760mm, 320mm. Double screw reduces backlash to almost ZERO. One of the most important factors in positioning error of a CNC machine is BACKLASH. One should remove backlash in hardware itself as far as possible.

Also use a top quality FLEXIBLE coupling if possible.

The motors that I am using have 3Nm holding torque. I bought them based on my premise that I would be using LEAD screws and SLIDING the axes over aluminium railings (instead of rolling on wheels) for which I would be needing a little over 2Nm torque.

However, I couldn't find precision lead screws in India and China. Importing them from Europe or USA would have been more costly than buying ball screws from China. And I found out that people were ball bearings as wheels to move the axes.

All these modifications brought down the required torque to around 1Nm. So am much smaller motor having around 1.5-2Nm holding torque should be able to pull it off.

you could complete this project in under 25k!
why are u using ball screws and heavy duty servos for hobby use?

Its not for hobby use actually. Made it as part of MSc project. Partly funded by a Govt agency. Balls screws are used to increase reliability & repeatability in operation. As ball screws are double-ball type and preloaded, greater torque is reqd to rotate them in comparison to normal ball screws. Hence the need for large motors. And they are stepper motors. Servo motors are much more expensive.

yeah, i got my cnc made for rs.26k total approx. it works real nice!

One more thing is I designed & made the controller and driver boards myself. So that's probably another reason the price is more than market rate.

ohk, thats nice, if possible keep this project as open source!
put it on website like instructables/github

Ya planning to do that. Thanks...