CNC Rotary table/lathe head indexing

[Kwackers]

This forum looked a bit empty so I've posted this here. Whilst not a 3 axis machine it is technically CNC. I have posted this design elsewhere so apologies if you've already seen it.

What and why?
It's a device intended to drive a rotary table, lathe head or any form of indexing device. It's cheap - the electronics running around £30 and (for a small 4-8" table at least) can use some of the appallingly cheap steppers and drivers we see around these days...

I made it after purchasing a set of division plates for my 6" vertex table, I played with them and then decided they were tedious and error prone. So I designed this.
Basically the controller connects to a stepper which you've coupled to your rotary table / lathe head / dividing head etc. Then with a couple of button presses it'll divide, move by an angle, move continuously for machining or if you're feeling adventurous you can program complex sequences of moves which can be driven automatically or with operator intervention etc.

Being a standalone device, it doesn't tie up a computer and is much simpler to use.

For example to divide a circle into 171 parts - turn on, press [2] (division) enter the number '0171' and press [G]. Each press of left or right will now move the table 1/171 of a circle anticlockwise or clockwise. Backlash compensation is automatically applied.
The current position in degrees, current division and total number of divisions are all shown on the LCD display.

Main Features:

* Stand-alone operation. No computer needed.
* Jog mode. For easy positioning.
* Division mode. Divide a circle into any number from 1 to 9999 parts.
* Degree mode. Move any number of degrees from 0.01 to 359.99 in 0.01 degree steps.
* Continuous drive. Table is driven continuously CW/CCW at one of the (selectable) 5 speeds.
* Program mode. Allows complex sequences to be carried out and automated. (10 programs can be stored)
* Configurable for any worm drive from 1:1 to 9999:1.
* Five speed settings.
* Configurable for all common stepper / driver combinations.
* Five machine profiles.
* Automatic backlash compensation.

Attached (should be) Rotary V2.0.zip - unzip this into a folder somewhere and double click on 'Documentation.htm', this file has links to other files including a manual, partslist, circuit diagram etc. Most of it should be self explanatory. Since the device is based around a microcontroller (18F452) I've also included the firmware for it (I notice elsewhere on the forums someone has very kindly offered to program these for free...)
I've also attached some photos of the completed unit and one of it in use (hooked to a 4" rotary table which is in turn bolted to my lathe head for a spot of gear cutting).

A number of these have been built by people in my local engineering club and people who've simply 'come by' the plans. There are a number of similar commercial designs, but I reckon this knocks spots off them and for a fraction of the price...

Hope it's of some use to people here.

[Lee Roberts]

Success !, the problem was that the file attachments were being stored in the database and not the file system on the server, when you tryed to upload the file the MySQL server was rejecting the file because the packet it was reciving was to big. Changed it to store files on the file server now so we shouldnt get that problem again.

Thanks Steve !

[rasta]

HI ; I have come by chance to this group , and saw this very nice proyect, my question is , can you please post the uncompiled version of the firmware? the reason is that I want to have a go at trying to port the program to the picaxe (I have no experience on it but it should be fun) also is im sucessfull I will try to use the circuit to do electronic gear hobbing, using the device to multiply the clock imputs.
regards
mariano

This forum looked a bit empty so I've posted this here. Whilst not a 3 axis machine it is technically CNC. I have posted this design elsewhere so apologies if you've already seen it.

What and why?
It's a device intended to drive a rotary table, lathe head or any form of indexing device. It's cheap - the electronics running around £30 and (for a small 4-8" table at least) can use some of the appallingly cheap steppers and drivers we see around these days...

I made it after purchasing a set of division plates for my 6" vertex table, I played with them and then decided they were tedious and error prone. So I designed this.
Basically the controller connects to a stepper which you've coupled to your rotary table / lathe head / dividing head etc. Then with a couple of button presses it'll divide, move by an angle, move continuously for machining or if you're feeling adventurous you can program complex sequences of moves which can be driven automatically or with operator intervention etc.

Being a standalone device, it doesn't tie up a computer and is much simpler to use.

For example to divide a circle into 171 parts - turn on, press [2] (division) enter the number '0171' and press [G]. Each press of left or right will now move the table 1/171 of a circle anticlockwise or clockwise. Backlash compensation is automatically applied.
The current position in degrees, current division and total number of divisions are all shown on the LCD display.

Main Features:

* Stand-alone operation. No computer needed.
* Jog mode. For easy positioning.
* Division mode. Divide a circle into any number from 1 to 9999 parts.
* Degree mode. Move any number of degrees from 0.01 to 359.99 in 0.01 degree steps.
* Continuous drive. Table is driven continuously CW/CCW at one of the (selectable) 5 speeds.
* Program mode. Allows complex sequences to be carried out and automated. (10 programs can be stored)
* Configurable for any worm drive from 1:1 to 9999:1.
* Five speed settings.
* Configurable for all common stepper / driver combinations.
* Five machine profiles.
* Automatic backlash compensation.

Attached (should be) Rotary V2.0.zip - unzip this into a folder somewhere and double click on 'Documentation.htm', this file has links to other files including a manual, partslist, circuit diagram etc. Most of it should be self explanatory. Since the device is based around a microcontroller (18F452) I've also included the firmware for it (I notice elsewhere on the forums someone has very kindly offered to program these for free...)
I've also attached some photos of the completed unit and one of it in use (hooked to a 4" rotary table which is in turn bolted to my lathe head for a spot of gear cutting).

A number of these have been built by people in my local engineering club and people who've simply 'come by' the plans. There are a number of similar commercial designs, but I reckon this knocks spots off them and for a fraction of the price...

Hope it's of some use to people here.

[Kwackers]

For anyone that's interested here's the source for v1.1 of the code.

With the exception of programming mode and some tidying up it's fairly similar to the version of the firmware included above.

It's intended to compile with Hi-Soft C.

Please note copyright on these files belong to me, I release them for personal use only.

[rasta]

Hi Kwackers;
thanks for posting the " C" file , I will learn a lot from it.
and also will help people that wants to develop their own rotary table.
Now can you please post the pcb file? I want to try to mill it or I can try to print the file ,as printing the jpg file does not come right , when I try to reduce the size
regards
mariano


quote=Kwackers;2919]For anyone that's interested here's the source for v1.1 of the code.

With the exception of programming mode and some tidying up it's fairly similar to the version of the firmware included above.

It's intended to compile with Hi-Soft C.

Please note copyright on these files belong to me, I release them for personal use only.[/quote]

[Kwackers]

Best way to print the PCB is to install Proteus Ares PCB software...

However, you can be a guinea pig and see if the attached PDF works. ;)

If it does - can you let me know?

[rasta]

hi ;
the artwork did not work for me, and when I tried to make draw the circuit board , I found that
The PCB artwork shows 2 pins of the pot connected to ground and 1 pin to pin 3 of the LCD connector.
The Schematic shows 1 pin connected to ground, 1 pin to +5V and the other to pin 3 of the LCD connector.
can you please shed some light into it?
thanks
rasta

[Kwackers]

Hi rasta,

I assume by "did not work for me" means you can't get the device to work?

I can confirm the PCB is correct (it's the one mine is built from), the schematic shows a voltage divider which will work, as will the simple variable resistor version on the pcb.

The circuit is pretty simple, as long as the PIC is programmed correctly and connected to the LCD then you should get a display.

Try the following.

Adjust the contrast - do you get anything on the display at one end of the contrast range? (This may just be squares.)

If not, check power (5v) is getting to the LCD and check the connections are correct.

If you get squares, this suggests either the PIC isn't running or the connections to the LCD are faulty (short or open circuit).

If you programmed the PIC yourself check the config bits are set (actually it doesn't look like they are contained in the .hex file in the above zip - I've attached a new .hex file that definitely has them set, please try this).

If the PIC is programmed correctly and the connections to the LCD seem ok then the only other thing that would stop it working is the area around the xtal and the two decoupling capacitors connected to it.

Hope this helps, let me know how you get on.

[rasta]

Hi ;
thanks for the prompt reply
by stating that it did not work for me , I mean that I could not have the print of the circuit board artwork with enough contrast to etch the fine tracks properly , so I've got a friend to do the artwork for me again , thanks too for posting the new hex file I will keep you posted
regards
mariano

[Kwackers]

Hi Rasta,

The PDF will be fine IF it prints out at the right size and your printer can print the blacks dense enough.

Some general tips I use for printing layouts which may help people...



I use an Epson photo printer (although I think any ink jet will do).

Use inkjet transparency paper (I bought mine from W.H Smiths - own brand).

Set the printer to black and white and use the best quality photo mode it has (This puts more ink down).

Make sure there are no blocked jets.

Put the paper in the printer, print and apply light pressure to one side has it feeds in - we need to do multiple passes and want to be sure it feeds identically each time.

Give the paper some time to dry, then repeat the above for another pass applying the same pressure in the same place to guide the paper in as it feeds. (It's not a bad idea to 'blot' the paper with a sheet of normal printer paper to remove any 'sticky' ink off the top between passes)

You should now see the blacks are pretty solid. If you want to be absolutely sure you cand do a 3rd pass - however I find it takes all night for the ink to dry enough before this becomes possible.

You should now have a high quality transparency, the rest depends on the photo board you use, chemical strengths etc. If in doubt it's not usually a bad idea to do exposure tests with scrap board similar to what you'd do in old fashioned photography.

Hope this helps.