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Messages - Cosha

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General Mach Discussion / Re: limit swithes
« on: July 11, 2011, 03:21:08 AM »
Do not panic & start ripping wires out here and there  >:D

I brought a PC base from E-Bay, Windows 2000 Cd Rom and a hard Drive for £15, you dont need a singing all dancing PC to run Mach3

I had lots of trouble when i was starting out and i still do, so dont feel too bad!

Can we have more information on your controller board, any manuals on the interweb?

General Mach Discussion / Re: limit swithes
« on: July 08, 2011, 01:27:41 AM »
From Other Sorces On The Interweb

Use Mach 3 Debounce

I put this one first because it is easy to try. Limits and similar inputs can be debounced in software using Mach 3. This can help to reduce noise sensitivity. Most sources recommend trying a debounce value of 1000 to see if it improves the situation. Values as high as 2000 are sometimes recommended.

Sometimes this debounce option can cause problems in homing circuits, such as strange reversals of motion, so be on the lookout. It is not a panacea. Lower values of debounce may make your switches more accurate and repeatable. It's worth experimenting to find the optimum lowest value that eliminates false hits from noise.


Mayve the 2500-3000 value is a little high, so try from low and work your way up?

Also, note that if it is noise from the machine try and run your signal wires and motor wires on different routes, or try get as much distace between them

General Mach Discussion / Re: limit swithes
« on: July 08, 2011, 01:21:53 AM »
Im not sure , but it sounds like your cables to the limit switches are not shielded?

I think CNC machines put out alot of 'Electrical Noise' that can fool Mach3 into thinking a switch has been hit...

Im *Sure* if you look for a 'Debounce' Setting and change the value to around 2500-3000 it will be fine!

Hope i right, this could be the most useful post i have made to anyone here  :D ;D

Hi John,

Thanks very much, im at work at the moment and my pc wont let me open it (No Fun Allowed)

Sure looks like a great wat of doing the job!!

Thanks Again!

That worked quite well!

I know someone at work who would be able to do this for me!

On another note about backlash...


Right up my street! I can make up some nice flanged nuts, with minimal backlash!

Ah, ok...

Sorry yes me being dumb then!

If i replace the 2 Y Rails with 2x fully supported rails i will have 2x rails free for the X Axis!  ::)

Currently My Y Axis is 720mm long and my X Axis is 575mm this will leave 145mm of rail sticking out the back.

No problem really As the Stepper motor is a good 120mm long anyway!

You will have to excuse me im very Dyslexic, i have it all up in my head, but it gets stuck at my elbow and i can write down what im thinking very well!  ;D

@ Jeff - Opps

I mean 400mm x 300mm - Hehe

@ Twaekie

I could get for around £150

2x FTSN_GW round supported rail - 16mm
4x TBR16UU Pillow blocks - 16mm

But then what to do about the X axis?

On the Y i was thinking of having:

2x rails/pillow blocks on the front 
2x rails and blocks on the back

*Should* hold it up alot better?

...and then again the same for the X gantry?

Idealy i would love to have some Hiwin profile rails all around - just trying to get the best bang for the buck :-)

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!


Share Your GCode / Re: Suppressor Designs?
« on: April 01, 2011, 06:59:46 AM »
Finally something i can chime in on!  >:D

Me pick me, i know a few tricks...

What Size round / grains will you be using?

For Example a 9mm will have different design/internal baffles to a .338

...any round that will go supersonic will be pointless for sound moderation, you cant silence a supersonic boom

...although you can controll the thermic flash and heat signature slightly with a moderator if your intending to hunt

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