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  #811  
Old Tue 28 August 2012, 01:30
danilom
Just call me: Danilo #64
 
Novi Sad
Serbia
You should try single flute cutters, recently I got one 6mm from a friend, it does wonders in aluminium. No melting, no bonding and no need to spray anything on it, pure fun!
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  #812  
Old Tue 28 August 2012, 03:27
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Hi Danilo

It was a 6mm single flute alloy bit i used !! They work very well.
Like you I was given 2 by a fellow CNC user but only one was long enough to drill the full 25mm of the bore.
Considering there was eight pulleys to do, I flooded them with oil constantly just to be sure.
The 4 big pulleys done are now and the hold down for the 18 tooth pulleys is ready to test.

Thanks for your tip on the cutter.

Regards
Ross
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  #813  
Old Wed 29 August 2012, 03:39
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Cutting 18 Tooth Timing Gear Bores.

Probably machined them too slowly but all are well and truly usable.

Here is how I clamped them to the CNC bed for machining.
The timber clamp is pinched around the pinion hubs with a screw or bolt then screwed to the machine.

Machining 18 Tooth Timing Gear.jpg

Regards
Ross
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  #814  
Old Wed 29 August 2012, 04:57
KenC
Just call me: Ken
 
Klang
Malaysia
Good job! That is a lot of effort!
Better keep it slow than to redo the job.
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  #815  
Old Wed 29 August 2012, 06:44
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Definitely not on the fast track Ken but learning how to made do with what I have.
As you say, soon I will be done and the effort forgotten.

Regards
Ross
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  #816  
Old Wed 29 August 2012, 12:43
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
..next thing you know, Ross will have a working 4th axis and start making those gears from scratch! Well done Mate.
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  #817  
Old Fri 31 August 2012, 04:18
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Hi Sean

Am I that predictable - guess so
What I did find was this http://gearotic.com/ from Art who makes the Mach3 machine controller application.
If one needed lots of different gears then it would be an easy path to pop them out probably in a hard plastic.

Belt Reduction Drives

Sent the DXF files off to the laser cutters.
I can report that MetalHead Mike's prices are very competitive.
It was $215 AUD for my design to be cut here.
Will will send a few photos once i gather up / make the rest of the bits for the drives.

I have a few questions for the forum so next post will set the framework, hopefully I might get some valuable input - more to follow.

Regards
Ross
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  #818  
Old Fri 31 August 2012, 05:49
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Optimising for Belt Drives

This Youtube video is a great visual reference for anyone who ever wondered about the practical difference between full step, half step and 10x microstepping on a stepper motor.
http://www.youtube.com/watch?v=8zVp1Ivs7Vs

The next part of the formula is the reduction in torgue as microstepping increases. This table explains the relationship very clearly.

Microsteps - Holding Torque
1 - 100.00%
2 - 70.71%
4 - 38.27%
8 - 19.51%
16 - 9.80%
32 - 4.91%
64 - 2.45%
128 - 1.23%
256 - 0.61%

The most vague part of the formula is the way torque decreases with increasing RPM of the stepper motor.
Looking at the Torque vs RPM curve of a motor somewhat similar to mine (maybe) here
http://catalog.orientalmotor.com/ite...prodid=3001048.
In summary the torque falls away rather quickly at increased RPM but does not seem to fall away as much as the additional torgue the belt reduction provides.
Makes sense as why would you do it otherwise.
Detent torque (the bearing, mechanical and magnetic stiction characteristics) further muddy the water.
It is hoped that any changed microstepping values chosen are less than where these forces might significantly alter accuracy, something like a 2x value at most.

My question is..

In a like for like voltage, amperage and driver scenario, is it worthwhile giving away some of the remaining increase in torque a belt drive may provide for extra resolution provided by increased microstepping.

In some ways the question could be rephrased as..
Do we require all the extra torque the belt drive provides to improve cut quality or could a balance of the two be beneficial.

Finally I realise that this all depends on the job in hand and that increasing microstepping values for jobs that don't need torque is possible but not really that practical.
So is it torque or resolution we need ?

Thanks
Ross
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  #819  
Old Fri 31 August 2012, 06:02
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Not enough resolution, the surface may be rough and you have to sandpaper
Not enough torque, the motor may stall and you have a gash (or fire)

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  #820  
Old Fri 31 August 2012, 07:58
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Hi Gerald

I laughed when I read your response.

The numbers initially point to me increase the microstepping from 10 to 16 (a 1/3 increase) after fitting a 4:1 reduction.
That yields an electronic improvement in resolution, a mechanical improvement in resolution and a marginal mechanical increase in torque at the pinion.
More from each parameter, that is by definition optimization
And I will buy some sandpaper just to be safe !!

Regards
Ross
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  #821  
Old Sat 01 September 2012, 05:34
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
I noticed the forums standard stepper motor driver the Gecko 203V is native 10x microstepping.
That might explain why most are silent as to how changes to microstepping might change performance in conjunction to belt drives.
The other more obvious explanation is that I'm a PITA as my mates so often point out

One last thought to record on the forum before I leave this one alone.

Changing the specification of the NEMA 34 ungeared motor to a higher torque motor when used in conjunction with a 4:1 reduction may help to restore some of the torque loss from my proposed increased microstepping. The detent torque unfortunately also rises along with the increased motor torque so with each change does not come without hurdles.

The reason I went down the path of belt drives in the first instance was because of this ...
"One of these inexpensive motors (MotionKing 34HS9801), with a belt reduction added at a later stage, will rival the performance of the "first choice" geared Oriental Motors mentioned right at the top"

I'm simply trying to test those assumptions initially made in 2006 and see if in 2012 tweaking a few things can give us a little more for roughly the same investment.
I have already run my machine at 16X microstepping and nothing bad happened.
Now I want all my torque back too .

Regards
Ross
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  #822  
Old Sat 01 September 2012, 07:44
danilom
Just call me: Danilo #64
 
Novi Sad
Serbia
Do you know that almost all drives morph speeds? above certain rpm all drives morph to full step to regain torque.
Even geckodrive. at 267 RPM it starts to morph and at 565 RPM it goes to full step

here it is explained:

http://www.geckodrive.com/how-morphing-works/
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  #823  
Old Sat 01 September 2012, 08:41
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Hi Danilo

My DM856 Leadshine driver manual makes no mention specifically of morphing.
I believe the feature your refer to as morphing is contained in the DSP or Digital Signal Processing algorithms within the driver but it makes no mention of the any micro stepping corrections at RPMs it might make.

In the end it is pointing to the difference between an analog and a digital driver.
I remember specifically choosing a DSP pathway assuming it would be more flexible over analogue but this does leave totally in the dark on specifics.

Thanks for your link as it all goes towards helping me build a complete picture.

Regards
Ross
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  #824  
Old Sat 01 September 2012, 13:39
danilom
Just call me: Danilo #64
 
Novi Sad
Serbia
I posted the question about morphing to the Eric from Leadshine here in this topic, as I am interested too.

At my friends (Pajka) in macedonia we used DM856, and they are more stable and quieter than my 2M982. I also blew one off with a short circuit in a cable jack and was able to fix it quicklu with a 0.1ohm resistor and a IRF540N mosfet .
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  #825  
Old Fri 07 September 2012, 05:37
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
LED Light made with the Mechmate

Today I made a 40 Watt LED Light with the Mechmate, it was a great exercise in what the machine can do.

The Machine made 2 x acrylic lens, an alloy mounting block for the LEDs and for the first time I made a PCB to mount the 4 LED drivers.
It is extremely bright and uses a measly total of 37 watts to do so.

Front
IMG_3512.jpg

PCB inside uses the exclusion method with the traces drawn in CAD
It was fast, clean and easy.
IMG_3513.jpg

The laser cutters are slow with my belt drive parts, so that project remains on hold for the moment.

Dry Machining of Aluminium
Forever the optimist, I had another go a dry machining.
Big fail and two dead 6mm end mills later, it all got thrown away.

My RP7 oil method works very well, however after my latest dry machining fail it was more than ever obvious that two things were needed 1. cooling and 2. lubricity.
The reason the spray oil method works is that it provides the lubricity to reduce the friction heat build up.
Compressed air alone (and lots of it) as a coolant was a poor second to oil.
The best cutting fluids however also contain water as when the water evaporates the change of state from water to vapour produces significant cooling.
This time as I dry machined I kept note of the workpiece temps.
Initially all goes well but a the heat builds eventually the aluminium starts to melt to the cutter.
In the end what this means is that if using fast feed rates and very shallow passes the heat input has time to dissipate and the aluminium remains machinable.
What this also means is an overall slower machining time.

So while the oil was working their is also further room for improvement using a glycol concentrate (I am assuming) and water mix.
All the water borne fluids tend to use a 20:1 dilution yielding enormous amounts from just a few liters of concentrate.
The diluted fluid is very slippy, so I can't wait to have a go with a squirt bottle.
While the pros all know this it takes time for someone like me with no previous exposure to run through all the options and find the best method for our machines.

Droplet Mister
The best delivery method for these water based fluids is a droplet mister setup.
I have experimented with how this is best achieved and short of having a good needle valve to control the coolant flow, all is working well.
The secret to forming droplets rather than mist is to have two separate air supply pressures in the system.
The fluid reservoir is held at a higher pressure than the final air delivery pressure.
The internet is full of pressures that people state work for them, however as I experimented it became clear that the difference in pressures was the real factor.
Using the same setup with two variable air pressure regulators I was able to have the system move from no coolant, to droplets and finally to a mist just by varying the pressure differences between the two lines.

Prototype settled, I will send a few pics once the parts for the droplet mister have arrived.
Ultimately I am trying to have a system that works to cut aluminium without flooding the area with excessive moisture.

Long post I know so thanks to anyone who read through to the end.

Regards
Ross

Last edited by Surfcnc; Fri 07 September 2012 at 05:40..
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  #826  
Old Fri 07 September 2012, 05:57
Regnar
Just call me: Russell #69
 
Mobile, Alabama
United States of America
Ross it sounds like you might have already found the plans for the DIY fogbuster but if you haven't a quick google search will pop them up on Pratical Machinist forum. Work great, mine was set at 10-15 psi.
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  #827  
Old Fri 07 September 2012, 06:00
KenC
Just call me: Ken
 
Klang
Malaysia
Great post! I enjoy reading every single word.
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  #828  
Old Fri 07 September 2012, 06:25
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Hi Russell

Yes had a look in fine detail but thanks for the link, always appreciated.
This is a good setup using the same water filter cartridge holder as the original.
http://www.youtube.com/watch?v=xQENewWM68Q.

My implementation of the needle valve is no where near as good.
If anyone knows what that neat brass coloured valve block is called / where they can be found, I would appreciate it.

Cheers Ken, really I just have a poor memory and have to write it down before I forget it

Regards
Ross
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  #829  
Old Fri 07 September 2012, 17:08
AuS MaDDoG
Just call me: Tony #71
 
Brisbane
Australia
Great post Ross, very thorough and very informative as usual you certainly do your homework !!
Well done, and a nice addition once you get it all up and running.

Cheers
Tony.
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  #830  
Old Fri 07 September 2012, 20:33
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Gidday Tony.

Ross
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  #831  
Old Sat 08 September 2012, 19:46
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Cutting Fluid Results

Did a quick test of this concentrate (for you Aussie people available at Hare and Forbes).

IMG_3516.jpg

The result was excellent. The machined part remained cool.
Significantly less odour than spray oil and an easy clean up.
Machining rates were significantly increased.

IMG_3515.jpg

I applied the coolant with a hand sprayer typically used in kitchens for cleaning.

Regards
Ross
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  #832  
Old Sat 08 September 2012, 22:41
KenC
Just call me: Ken
 
Klang
Malaysia
Ross,
How often do you spray? Do you have to keep pumping at the bit throughout the cutting action?
I brush on little kerosene on the cut path (on the alum) with a small brush for kitchen use. but when you have to do that for 5 hours continuously (time to cut a 4'x8' 1mm Alum sheet... it gets a little frustrating with muscle ache as side effect...
I've been thinking of trying out hand sprayer for a while but procrastination gets int the way.
The Zero Fogger seems the ultimate solution. Thanks again to Russel for bring up this topic.
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  #833  
Old Sat 08 September 2012, 23:07
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Hi Ken

Once every "Lap" seemed to be quite enough.
Used 100ml of coolant or 5ml of concentrate costing 5 cents.
Still smiling.

Regards
Ross
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  #834  
Old Sun 09 September 2012, 00:40
sailfl
Just call me: Nils #12
 
Winter Park, FL
United States of America
Ross

That turned out very nice.
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  #835  
Old Sun 09 September 2012, 01:37
silverdog
Just call me: Sergio #70
 
Rome
Italy

I'm astonished ! what incredible possibility has the mechmate ... masterly driven by a creative owner !
just curiosity which mill did you used for "helen" ? it looks a very small sign.
Thanks
Sergio
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  #836  
Old Sun 09 September 2012, 02:04
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Hi Sergio

3mm 2 flute solid carbide end mill at 30mm/sec, 22,000 RPM and .3mm depth of cut.
Bevel (done first) 90 degree 3mm V bit at 20mm/sec, 22,000 RPM and .4mm depth of cut.

The smaller the end mill the faster the RPM is a general rule.

Regards
Ross
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  #837  
Old Sun 09 September 2012, 07:40
Regnar
Just call me: Russell #69
 
Mobile, Alabama
United States of America
Ross, I wish I was able to remember all the links I use to have before IE crashed on me. I use to know where to get it but I want to say it was for a small OA torch. Also here is the link to the Patent to for Fogbuster. http://www.google.com/patents?id=khs...390854&f=false
Reading the abstract will give you the important numbers like nozzle size and length. For the nozzle we use a Mig Tip. We did make our own Valve out of .75" Brass. Turned down the end of a 1/4 28 socket head bolt in a drill press to look like the picture. Took no time with a angle grinder and light touching.
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  #838  
Old Mon 10 September 2012, 04:42
KenC
Just call me: Ken
 
Klang
Malaysia
Quote:
Originally Posted by Surfcnc View Post

My implementation of the needle valve is no where near as good.
If anyone knows what that neat brass coloured valve block is called / where they can be found, I would appreciate it.

Regards
Ross
I think precision liquid metering needle valve is the generic name.
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  #839  
Old Mon 10 September 2012, 06:07
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Coolant Unit

Thanks Russell and Ken

Tried tapping an Acetal block as per the diagram - failed so will try again later.

Got the bottom end of the system done though.
Cross threaded the plastic on the canister input side as I was getting tired.
Think I got away with it.

The design can deliver air only, coolant only or air and coolant in any ratio due to the independent valving.
The input regulator allows full pressure supply to other air powered devices like the vac pump.

Can't post any more photos into the forum at present so I will get on to that.

Regards
Ross
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  #840  
Old Mon 10 September 2012, 18:34
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
IMG_3517.jpg

Regards
Ross
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