[Simon C]

Ok im gana be converting my 7x14 minilathe to cnc over the next few weeks/months, i was in the middle of building a plasma/router table then i got this lathe as a christmas presant from my GF (yup, a GF that buys machine tools as christmas presants, shes definatly a keeper) so the plasma is on the back burner till this lathe is finished. this particular 7x14 is from Amadeal £380 inc VAT has a 550 watt motor 100mm chuck and camlock tailstock also has spindle rpm readout.

this is what i intend to achive.

Ballscrews on X and Z.
Spindle speed control by Mach3.
Spindle index pulse for threading/rpm input to Mach.
Full enclosure with a slideing door at front for access.
Flood coolant controlled by Mach.
And possibly an auto tool turret but will be useing a QCT to start with.

Up to now i have done most of the X axis. il be useing a 200oz-in stepper and a class5 ballscrew 8x2.5 pre loaded. the nut is only 17mm Dia so no prob fiting it under the cross slide. the Z axis will have a 16x5 ballscrew same class and preloaded and a 425 oz-in stepper, both axis are direct drive. im hopeing the drivers and BOB will arrive tomoro from Worldofcnc and the Z screw and bearing supports later this week. il take some pics of the cross slide tomoro and upload them, heres a few pics of the spindle index and what will eventualy be my coolant tank (deep fat frier that never got used and so claimed for my project )

Let me know what you all think, any advice,tips,questions, please feel free to chip in. (il need lots of advice on the electrics side of it)

[Simon C]

Does anyone see a potential problem haveing 2 optical switches so close together? am also worried that the bottom one is close to the spindle moter and might be affected by electrical noise. the one thats mounted to the little green pcb is the original one that came with the lathe for the rpm readout, i wanted to keep it on there so i can mount the lcd screen that comes with the lathe on the control pannel that il make wich will have Estop,cycle start buttons and other things. the switch at the bottom is the one i fitted that will go to my BOB for mach3. still not sure how to wire this switch to my BOB, i do know i need a separat 5v power supply and some 220 resisters but wich wires go were i duno, its an optek OPB917BZ

[Simon C]

Ok heres some pics of the almost complete X axis cross slide. still need to machine a 6x1 thread on the front of the ball screw and machine the other end of it to fit the 7mm ID rear support bearing and 6.35mm motor coupler. might try useing the tool post grinder to machine the back of it, this stuff is a pig to machine with carbide tip tools, have to re sharpen them every few passes

I decided to put the stepper at the back as it overhanges the bed less this way and i think the flat bed way will ware less than the V bed way would with the same amount of weight as i think the V shape ampilfies any weight put on it causing increased ware and the weight of the apron at front will help to ballance things out.

im useing a double row angular contact bearing at front, 30ODx10IDx15Wide, smaller would have been better but thease were smallest i could find and only £7.50 from worldofcnc. rear bearing is just a standard bearing 22ODx7IDx7Wide.

Drivers didnt arrive today, hopefuly tomoro. cant tell you exactly what type of drivers they are cos i duno myself, but the guy at worldofcnc told me they would run a 425oz-in stepper wich is the biggest il be useing on this machine, heres a link to the drivers Controller Kits

[TXFred]

Does anyone see a potential problem haveing 2 optical switches so close together?

They should be fine. I built an optical ignition for my motorcycle using two sensors. They're much closer together and they never have crosstalk issues.

And optical sensors are good at ignoring electrical noise. I think it will be fine.

[blades]

Lookin' mighty nice Simon!

[Simon C]

Thanx for your reply TXfred, you put my mind at rest. I guess that is the ultimate test for an optical switch being so close to the HT leads on a motorbike and still functioning properly.

[Simon C]

Lookin' mighty nice Simon!

Thankyou Blades.

[Simon C]

Well i finished machining the X ballscrew today, i found a little trick to machineing thease more easily. trick is you just gata be brave and take deep cuts, i was being to catious and only takeing mabe 0.04 - 0.08 mm per pass but this just tends to just "pollish" the cutting edge very quickly. it cut much better when i was takeing 0.7 - 1 mm per pass. now just have to bore out and cut a m15 x 1 thread in the ball nut mount and mount a home switch and the X axis will be finished. gana use the same type switch for the homes as i did on the spindle index, Optec OPB917BZ, optical interupt switch, still have no clue how to wire thease to a BOB yet lol. Also orderd the spindle control board yesterday Zapp Automation Hope it works with the BOB im useing, has anyone had any experience with this particular board?

[Simon C]

Well i finished the x axis today and hooked it up to the Hobby cnc board that i use to run my mill. Doesnt appear to have any backlash but il check that later with my DTI. also made some heavy duty gibs for the z axis out of 20mm x 10mm cold rolled square bar, not sure if this is the best materiul to use for gibs, only used it cos i had some lieing around. Still havent recieved the Z ballscrew or the drivers and BOB so not alot i can do till they get here, mabe il work on the coolant system till they arrive.

Heres a coupple pics of the completed X with the 305 oz-in motor. the Xbox 360 u can see in the pic was gutted and now has a hobby cnc board and 38V psu in it, gana use the original Xbox psu to power the coolant pump it puts out 12V 12.1A it also has a 5V 1A output that i might beable to make use of. coolant pump im useing is a 12V submersable Diesel transfer pump that i have lieing around.

[Simon C]

This is a link to a youtube vid of a test i did to check for backash. rapid speed was 2300mm/min if i remember correctly, probly would go faster. hobbycnc pro board on half micro steps with 38V ps. the drivers il be useing on the finished machine are 1/10th micro steps so the motors should run much smoother i hope. [nomedia="http://www.youtube.com/watch?v=Mbqzr6ouufc"]YouTube - CNC Mini Lathe conversion Backlash Test[/nomedia]

[eartaker]

Awesome work going on here. What are your plans on covering the screw?

[Simon C]

Awesome work going on here. What are your plans on covering the screw?

Thankyou eartaker,
Im planing to make a cover out of sheet metal that will be longenough to cover the stepper aswell, it will kinda wrap around the whole of the motor mount and cover the rear part of the top of the cross slide, not sure if this will cause motor cooling problems or not. i dont have a sheet metal bender. so il buy a small one. have been looking at this one New Page its the one at top of the page. only problem with this one is i plan to make a full enclosure for this lathe so with this small bending machine il have to make the long parts in 3 pieces and silver solder them together, the longer benders seam to get very expensive as they get longer, idealy i need one that will bend 36" long.

[Simon C]

Thought i would do a quick update,
I havent been able to do very much mechanicaly latley as im still waiting for the Zaxis ballscrew to arrive,been waiting a month now, so i have been working on gathering all the electronics and makeing them all work together before anything is mounted on the machine. It all seems to be working nicely although i did have a few problems here and there. i managed to destroy the circuit board that controls the spindle motor , was trying to find out which 2 of the 3 wires on the speed control pot i needed to connect to my 0-10v spindle control board,so i checked the middle wire with 1 of the outer wires on the pot and it was puting out 7.34V at max speed,great,then i decided to check the 2 outer wires to see what voltage they were,so i put the meter on 600VAC cos i wasnt sure if it was ac or dc,this was a bad idea,soon as i put the probes on the 2 outer wires the board exploaded blowing 1 of the tiny motor tuning pots off the board :withstupi . so now its gana cost me £80 for a new board from Amadeal. oh well atleast i now know which 2 wires NOT to connect it to. The spindle2 board that im useing to allow the computer to control the spindle speed was also a little tricky to get working proply. was haveing problems geting it to give out a linear voltage till i found some info on the net about it, so i tried the settings they recomend and it worked perfectly. the settings are: steps per 2000, velocity 65, accel 0.7, step pulse width 10, those are mach3 settings btw. the pulse width 10 worrys me a bit as it seems to apply this to all the axises not just the spindle, does anyone know if this will affect the performance of my stepper motors in any way? Oh and i managed to find out how to wire my optical switches to a break out board, heres a link to the thread that will explain how i did it http://www.cnczone.com/forums/genera...witch_bob.html
Below is a few pics of the electronics im useing.
The motor on the left of the pic is a nema23 with 425 oz-in torque and the one on the right is also nema23 but with only 260 oz-in both from Zap automation. the powersupply is 48V 7.5A also from Zap. the drivers are 4.3A and came with the 5 axis break out board from Marchand dice. the cooling fan is huge, i got it from Maplins, its 240VAC 22watts and 120mm Dia, this thing realy blows

[Simon C]

This update is well over due, truth is i havent been able to do hardly anything on it for the past 3 ish months. Iv had a nightmare of a time trying to get the ballscrew and bearing supports from Marchantdice/world of cnc. took took over 2 months of emails and phone calls and in the end never got the items and didnt even get a full refund, anyway i had to order the parts from a diffrnt company, decided to try Zap automation, and they arrived 2 days after i placed the order so il be useing Zap for all my cnc hardware from now on. I did manage to make a cover out of 0.8mm steel sheet for the X axis stepper and ballscrew, it also has a small cooling fan built into it to keep the motor cool. have no pics of the cover right now but il take some tomorrow and post them. Also decided to replace the headstock bearings with taperd rollers, i was a bit reluctant to remove the headstock from the bed cos i didnt want to mess up the alignement, but after reading Danny X's thread on taperd headstock bearings it prompted me to do the same. havent got round to puting the new ones in yet but will do soon. it cost me £40 for the pair but they are top quality ones. Next job is to bolt the lathe bed down to my mill and face mill and tap the positions for the bearing supports, while the bed is on the mill il need to make a light cut to "true up" the underside of the lathe bed were the saddle gibs ride. the underside isnt parallel to the top surface of the bed, so it would be impossible to adjust the gibs to give a good fit along the whole travel of the bed.



Below a few pics of the ballscrew and bearing supports mocked up on the bed.

[bluezone]

New build. I have the same lathe that im repairing. Would you be able to take a photo of the pulley that the timing belt goes on. The pulley on the H/L gear shaft. Thanks

[Simon C]

bluezone, thease are the pics of the timeing pully, the bore is 10mm, the width is 10mm and the OD is 45.55, im not sure what the DP or the pitch is, but i guess a few google searches would soon find that out. oh and it has 31 teeth.


if you need anymore info/pics let me know.


regards
Simon

[doorknob]

If it's not too much trouble, I'd be interested in knowing the part numbers for the ballscrews, ballscrew nuts, and supports that you ordered from Zap Automation.

Not a big deal if you don't have that info handy...

[bluezone]

Thank you. Now I know what it looks like. Would you happen to know how much teeth it has?

[Simon C]

Thank you. Now I know what it looks like. Would you happen to know how much teeth it has?

It has 31 teeth

regards
Simon

[Simon C]

If it's not too much trouble, I'd be interested in knowing the part numbers for the ballscrews, ballscrew nuts, and supports that you ordered from Zap Automation.

Not a big deal if you don't have that info handy...

Doorknob, heres the part No's for the main hardware i used so far from Zap.

X axis ball nut = G ten brand R08-02.5-RSW-P0.
X axis ball screw spindle = G ten brand R08025.
Z axis ball nut = G ten brand R12-05T3.5-RSW-P0.
Z axis ball screw spindle = G ten brand R1205.
Z axis ball screw bearing support (floating end) BF10-C7.
Z axis ball screw bearing support (fixed end) BK10-C7.

lemi know if you need details on the other bits like motors and motor coupplers.

regards
Simon