Looking through new windows #114 - Isarn, Thailand

[Mrayhursh]

Some brass hooks on the keys would be a great. My wife just walked in and ask me where her keys are. Are you cutting down neighbors tree for wood?

[lonestaral]

What a piece of kit this machine has turned out to be.
Got the bugs out of the system.
10 hour shift today, faultless.
Only stopped for load/ unload & tool-change.

Only problem was with the router, new brushes tomorrow.

Should have built one years ago.

[Tom Ayres]

I love the idea of a "Meet the Beast Party". I wish you many great successes!

[lonestaral]

I wanted some 20mm dowels.
Back home I would have bought a broom handel.
Here broom handles are made fron bamboo.

I have not got a lathe (Next project).

I made a simple 4th axis.
The motor needs gearing as it lost some steps.
It did the job, got me out of a hole.

[racedirector]

They say need is the big creator of ideas, very impressive adaptation Al!

[darren salyer]

Great Job. I've thought that using two 4:1 gear reduction plate sets, one driving the other, would work well for reduction.

[lonestaral]

I wonder if I could cut my own gears (Wood or Plastic)
For the reduction.
Got the machine, just need the time and materials.

[lonestaral]

A local woodcarver gave me a piece of a root from a tree.
He asked could I put it through my saw and make some Buddha's.
A very heavy and dense wood it was.

So today I did the routing.
33 in strip form and 3 specials.

[Tom Ayres]

I really like the wood, not in to Buddha, but cool none-the-less.

[MetalHead]

That looks cool. How tough was that wood on the bits?

[pblackburn]

What type of wood is that Al?

[lonestaral]

Sorry, but I do not know what it is.

Not being a native of this neck of the woods it is very hard to find out what something is, where it came from or what it is worth.
The guy might not know himself.
There might be a local name, it might be what the monk calls it.

It smoked a bit on some cuts. I had the router on bottom speed.
Feed 500mm/min.
It also left a resin type deposit on the bit.
It files like cast iron.
Smells nice.

Thats about it.
Parts delivered, customer happy.

[KenC]

Looks like Siang-Malam.

[lonestaral]

I ordered some profiled plates last week for a machine I an building.
No, it is not another MechMate.

After a week of waiting they were ready.

The 42mm holes in the plates were 40mm.

Off to see my mate Mechmate.
16mm two flute router bit, router on bottom speed.
Lots of sparks and noise.
5 plates, 2 holes in each.
Job done.
Cutter to go to the grinder tomorrow.

[KenC]

Nice job.
Careful with your plunging rate, those spindle bearing are expensive.

[silverdog]

Originally Posted by lonestaral

The motor needs gearing as it lost some steps.
It did the job, got me out of a hole.

Somewere somebody told that you can't use microstepping for the rotary 4th axis because it will not give a precise 360° ..... so you absolutely need reduction and more than the usual 4:1 .... I have no experience nor I am shure this is true. Anybody can confirm ?

[pblackburn]

I would not know if that is totally accurate. Whether it is 200/r or 2000/r, it is still 1 revolution. Granted a servo with feedback would be optimal. You can dial the stepper in really close using your step calculator and spinning multiple revolutions using an indicated plate and long indicator arm (24" or more). I would think the problem would be more from the limited amount of torque that caused the loss of steps while turning against the cutter. Too many dynamic forces at work. The lowest reduction I have ever read about with a 4th Axis is 3.6:1. But as Sergio stated, that is definitely worth looking into to verify. You will have backlash with any reduction setup unless it is a Zero Backlash reducer like a harmonic drive.

[lonestaral]

Very probably you will not get a precise 360 Degrees.
Very probably you will not get a precise 0.001 mm or 0.0001"

As I am working in wood which will change size with humidity and temperature I will not worry about that.

As I am not making components for Aerospace applications, that is not a worry either.

I am more than happy that I have built a machine by myself that has exceeded my expectations.
At this stage in my life I do not need to split hairs any more.
I had enough of 0.001mm tolerances during my working life.

Thank you for your comments.
I am sure that those who need a more accurate machine will pay heed.

I will get around to gearing the 4th Axis and I will post progress and results.
At the moment I am constructing a manual lathe with the option for CNC control.
Also a bandsaw build is on the horizon.
Nice to be busy.

[pblackburn]

It was not meant to offend.

I have mine as a double belt reduction but I would never tell you to only stop at my level. I would not want to leave someone wanting more. Tell them the best and let them make there own decision.

You are right about wood, from the time you start carving to the time you finish the wood will vary somewhat unless you are in a controlled environment that the wood was also stored there for a long, long, long time.

If you were putting this on a milling machine, I would not recommend anything under 50:1 at the lowest reduction.

[KenC]

I've not started work on my A-axis yet, but when I do, I'll surely have higher gear ratio for more torque to ensure the job piece will stay in place when its supposed to. The resolution & precision that came with it are bonus.

For non-metal work, 50:1 is too hard, 20~30:1 should be feasible using GT2 belts & pulley.

[lonestaral]

No offence taken.
I welcome all comments.
I am sure that a Rotary axis build is worthy topic by itself.
Worm and worm gear would give plenty of reduction.
Have to visit the scrap yards around here.

[lonestaral]

http://www.thingiverse.com/thing:41161

Something like this would do.
Anyone got one of them laser things ?

[KenC]

Worm gear will be cheaper to make, but I prefer working with belts, Its not about the precision or resolution, I hate seeing double lines cause by backlash. 2 stage 5:1 will easily give 25:1 Since there is only 1 motor required, 4 pulleys should be affordable.

[darren salyer]

I've gotta start on a 4th axis.....

[silverdog]

Me Too

[pblackburn]

If you go belt drive double reduction, it will increase the amount of movement as two belts will have the ability to flex. So it all depends one how you do your wrapping and your toolpath is generated. Make sure you buy good quality belts. I opted for a 16:1 combined belt reduction when I built my A. Later down the road I would like to opt for a low or zero backlash gear head but for now. Belt reduction is fine. Just wish I could finish the table mods.

The effect only has a chance to occur while rotating fast one direction and stopping to reverse direction. All depends on the surface cutting speed.

[darren salyer]

Sorry to continue the hijack....

I've not done much research on this, how much reduction is possible with just a single set of pullies and 1 belt?

[silverdog]

I think it's not so easy to find a big pulley ... but if you find it yes is possible
Anybody knows Harmonic Drives ? are a possible solution ?

[pblackburn]

Yes, but they are $$$$. You can get a harmonic drive gearhead or low backlash planetary gearhead. I have looked at it.

[pblackburn]

Darren,
My 7:1 reduction on my X, B and Y have a 18 tooth pulley and a 130 tooth pulley. The 130 tooth pulley is 9.125" in diameter. More feasible to use two 4:1 or 5:1 reductions.

Plus they were expensive