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Topics - Cosha

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Show"N"Tell ( Your Machines) / New/Update CNC Machine Brain Storm...
« on: June 27, 2011, 04:52:53 PM »
Hello everyone!

Ok today after looking at my CNC machine, and having a quick chat with Mr Tweakie, the machine really does need an update...

...and besides, it’s always fun to build right...right?

I could get a bigger machine bed/cutting area but more importantly more of a stable rigid machine!
For the size of the machine, I only get a 40mm x 30mm cutting area; this is for a few reasons:

Update 1 –Flying Gantry - In design stage

The ‘over-hang’ from the flying gantry is not enough – Currently my Kress Milling tool will over hang the front of the machine by about 100mm! Yes allot of wasted area huh?

So my new design will offset that, and the gantry up rights will lean further back to salvage back that wasted area! Hopefully the Kress will sit bang in the middle

Update2 – Backlash – In design stage

Backlash – everyone loves backlash, well now that I want to do some relief work, and more accurate work (maybe a little bit of really soft aluminium’s/brasses)

0.8mm in the Z Axis
1.2mm in the Y Axis
1.3mm in the X Axis....

...Is now far too much

Currently my machine uses TR12x3D Trapezoidal Spindles with LRM12x3D Trapezoidal Nuts
(From www.Worldofcnc.com (Great People, Great Service)

So, adding some sort of anti-backlash device to the brass Nuts is the way forward here? Thoughts?

I would love to go ball screw with Zero backlash – but currently, i just do not have the funding for such a jump.

Update3 – Rigidity – Part A -In design stage

My machine is based around 25mm marine ply, solid stuff! I’m just wondering on how much it has warped over time! As usual, i would love to build an 80x20 aluminium machine, but sigh, cost! Plus i got allot of the marine ply free! Bonus!

Here you can see my machine:

Notice that i have only 6 grounded solid steel linear rails, and only 2 linear pillow blocks per side, I'm thinking that because the flying gantry and Z Axis is so darn heavy, I’m wondering if this dips in the middle of the movement!

I’m thinking of added an extra 2 pillow blocks to each side of the gantry to overcome this a bit better, and to make it more ridged.

I like the way the Fireball machine looks, and might try and model a new machine off one like it!

Thoughts on both types of design?

One above and below or side by side?

(Please ignore my rubbish CAD drawings)

Also notice that i don’t have a bottom ‘Bed’ the weight of the whole thing could push the whole machine out – that I will have to fix somehow!

Update3 – Rigidity – Part B -In design stage

Now if you look at the part where the Z ‘head’ meets the Y gantry, I get a feeling that the Z axis is top heavy, you can just notice where I have a bearing behind the Z axis push the bottom of the Axis out level, after time with a metal bearing on soft wood, its formed a channel. This must be replaced, again with an extra 4 pillow blocks and 2 linear grounded rails!

Do I do the same as above?

Update4 – Extras –-In dreamland stage

Things like Auto tool zero etc..Basic stuff!

Please, any thoughts would be great – for around £120 I can get the extra rails and pillow blocks, which I could afford!

Thanks everyone!

General Mach Discussion / Mach3 backlash settings...useful?
« on: June 02, 2011, 07:57:31 AM »
unfortunatly i only use Trapezoidal ball screws and rubbish brass Trapezoidal nuts for my cnc machine...

I know its not ball screw and i know the accuracy will be lower!

I have eleminated any movement from the steper motors/couplings, these now sit flush againts a bearing either side of the mounting

i still have a lot of backlash im gussing from the Trapezoidal set up i have...

i 'guess' i could add another Trapezoidal nut to each axis but i dont want the machine to be too tight...

i have a dial indicator and have looked at the backlash feature on mach3 but i want to know the best way to record the actual backlash...

do i set a zero on one axis, jog around and the send it back to zero and record the difference? or is there another better way!?

Thanks all!


General Mach Discussion / Is Mach Stopping My Stepper Driver?
« on: December 12, 2010, 03:13:00 PM »
Hello Everyone...

Im Begging Anyone to help me with this, i have tried everything I Can Think Of.....

Ok, i have been using Mach3 for 2 years on my little desk top CNC Machine.

I took out my machine to take to a workshop to get a few bits sorted, i got there any for some reason my X movement has gone totaly...

I have opened my CNC controller, all 3 stepper boards have power, all LEDS are showing that there is a correct signal from My desktop to the controller, and 2 of the 3 stepboards are working perfectly...

So what changed in the 30 min drive to the workshop?

I have spend 2 days SOLID trying to workthis out and i just can't im totaly upset about this as i dont think there is anything i can do...

Can Mach3 totaly stop a signal getting through to my cnc controller?

I cant find any documentation on my stepper boards, all i know is there 'Langenfeld 2.1a stepper board rev 1.2'

I have checked and re checked everything, but i can find out whats stopping this motor from moving...

I/O Port On PC = 0x379 - Same as Mach3

Like i said the other 2 motors are working fully under Mach3 control, now im at a loss...

Can someone throw some ideas that i might have missed out on?

Thanks in advance...


General Mach Discussion / Motors get Your hot motors!!!
« on: June 24, 2008, 09:36:53 AM »
hello all...

yeah i know me again!

the machines doing fine, one problem? how hot do the steppers get normaly? i expect some heat, but mines fairly hot to the touch!

now another problem i have got is i dont know the turns on my steppers to see what they are...

the lead screw is this


i have used the inbult MPG in mach and it has worked out that one step is 133.666666666666666 now that cant be right????

i have read, re read the mach documents and searched day on night here but i have still got hot motors (i think)

what sort of values should i be looking at? i stared with 500 / 50 / 5 in motor tuning


General Mach Discussion / Strange Mach3 proplem please help
« on: June 18, 2008, 04:51:52 PM »
hello all thanks for reading this...

ok my understanding of all this is new to me so bear with my non tec terms lol!

ok so im running mach3, i got my motors to move perfectly everything set up no problem

now i rebooted my stand alone windows 2000 pc with only mach3 on it and the motors wont move, everything is working as it should mach says the motors are moving but the very starnge this in that the stepper motors sound as if there moving but they actualy dont!

loss of power? im not sure? i have tried quite a few things but i know its going to be some little setting somewhere i have missed.

ports and pins are 3,2 5,4 7,6 and all port 1

and that is as much as i can say? ox378 port, 25hx kernell etcs nothing else selected any ideas?

i have spent 5 months building this baby and now its not working and im heartbroken!



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