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1  User Video Links / Your Videos / Re: Two rotary tables, cutting a bevel gear -- octoidal tooth generation. on: September 21, 2018, 10:51:03 AM
Hi Kirk,
I think Sherlines are a great value. There is always a glut in the second hand market. Technical schools get grants and buy lots of them, then they are auctioned off when the next grant comes in ten years later. The huge supply, and the interchan geability is great. If you break something or wear it out (I never have), you can buy a replaceme nt easily. The used Sherlines I have bought are worth as much as they were when I bought them. Except for my first machines, I always try to buy Sherline stuff used, and only buy new if the parts I need are unavailab le or expensive on the used market. One thing about CNC is that I have been able to sell some of my accessori es -- radius cutter, threading, and have hugely expanded what I can do:
https://youtu.be/AXiFeOCwV28
--Justin
odhner.co m
2  User Video Links / Your Videos / Re: Two rotary tables, cutting a bevel gear -- octoidal tooth generation. on: September 17, 2018, 03:40:31 PM
Art,
The Gcode is shockingl y simple once you've worked it out, but it feels impossibl e at first.

The hard part is setting up -- getting the rotary axes to intersect, and touching off at that virtual point of intersect ion.

Then there is the minor subject of having to build the machine!

This is a paying job. They're paying decent money, but it is more work than it is worth. It is a nice project, and a worthy cause.
Schanck Observato ry Times
https://www.facebook.com/670361143169824/

I used your software to make wire frames, rotate them around, then photoshop them over the not so good photograp hs of the original gears. It helped to confirm the toothcoun t....

Someday, I'll be able to actually feed myself making gears!

--Justin
odhner.co m
3  User Video Links / Your Videos / Two rotary tables, cutting a bevel gear -- octoidal tooth generation. on: September 17, 2018, 01:11:10 PM
This is a short video of a pair of rotary tables rolling a conical blank against a virtual crown gear with an embedded flycutter . If the tooth faces of the virtual crown gear are planer/great circles, the tooth faces of the generated gear will be octoidal.

https://youtu.be/RxRbuPIKu6I

--Justin
4  General Category / Laser Stories / Lasers for cleaning metal on: July 11, 2018, 10:31:17 AM
Hey guys,

I've seen the half million dollar industria l rust ablating lasers on youtube:
https://youtu.be/Q8q3DZB_l6M

I was wondering if one could use this on a smaller scale for cleaning very small stuff. I often have to clean small brass parts that are corroded. They have very important textures and shapes, such as fine threads and engraving s. The problems is the oxides are tuffer than the metal, and anything that will remove the corrosion will obliterat e the brass. These lasers would be perfect, were it not for the $$$$$

I only need to clean a pinhead area at a time -- very small stuff.

So I ask you all:
What kind of laser are they using? Wavelengt h etc.

Are there standard Chinese engravers that could remove corrosion on a very small scale?

I've heard of shiny metals ruining lasers, is that an issue for corroded, amorphous lasers?

I'm on a low budget, so combining a CNC laser engraver/cutter with some cleaning would be awesome.

Any help/advice is appreciat ed.
5  User Video Links / Your Videos / Re: Hand G-code brass cycloidal tooth gear. on: June 17, 2018, 02:58:58 PM
Thanks Art,

I do the same thing with involute teeth, but have not videoed it; I'll post it when I have.
Next on the agenda, saw shaving octoidal miter gears -- I have a potential customer for these!

Your software always has a shortcut prominent ly on my screen -- I often use it to make a wire frame to photoshop over photos of partially obscured gears -- it's a quick way to accuratel y confirm tooth counts and pressure angles.

--Justin
Odhner.co m
6  User Video Links / Your Videos / Hand G-code brass cycloidal tooth gear. on: June 09, 2018, 10:25:34 PM
https://www.youtube.com/watch?v=UNiuqz_VIJ0

Using hand coded G-code to cut a 1/2" brass gear for an orrery. It's running on LinuxCNC using parameter calculati ons and "O codes". I set the basic definitio ns for the gear -- number of teeth, pitch radius, center to center distance, etc. Then the G-code makes the simple linear and arc motions that interpola te to create true epicycloi dal teeth. The gears don't conform to horologic al standards, but they are mathemati cally and geometric ally correct, and the pairs mesh perfectly . The results are actually amazing -- smooth enough that only a very light pass with a 3M radial bristle dremel wheel polishes off the burr.

--Justin
7  General Category / Laser Stories / Re: NEED HELP WITH CLOCK NAME on: May 08, 2017, 05:21:57 AM
"The Short Then"
8  General Category / Gear Discussions / Re: Just fell over an interesting gear simulation maybe of interest to others. on: March 09, 2017, 12:13:23 AM
No one took the bet -- you have to risk loosing to win.
9  General Category / Gear Discussions / Re: Just fell over an interesting gear simulation maybe of interest to others. on: March 06, 2017, 09:27:42 PM
Whew, my bucket of brass gears has what I need  -- I can only think in metal.

Sun gear:    40
Ring gear:    96
Planet A1:    36
Planet A2:    20
Planet B1:    32
Planet B2:    24

They run well, but the backlash allows arrangeme nts that work nicely, yet are clearly not "correct". I can tighten or loosen the train by jumping teeth -- convenien t, but not very rigorous. These are off the shelf 48dp Boston Gear gears.

It is creepy that the three 'diagonal' gears are able to wiggle.
10  General Category / Gear Discussions / Re: Just fell over an interesting gear simulation maybe of interest to others. on: March 06, 2017, 08:23:27 PM
Intuition engine down for servicing .
11  General Category / Gear Discussions / Re: Just fell over an interesting gear simulation maybe of interest to others. on: March 04, 2017, 08:08:45 PM
I'm going to bet $5 that there are no exact, non-trivial solutions for "asymmetri c planetary gear trains." The intuition is that both the circumfer ence and the radius appear in the equations I see. The circumfer ence and the radius are related by the factor Pi, which is irrationa l. Gears don't like irrationa l. Heck, the system is probably transcend ental too!

By exact, I mean the pitch circles of the four gears are tangent and not slipping.
By non-trivial, I mean the four gears have four different radii, and the number of teeth is not zero or infinity.
12  General Category / Virus Warnings / Re: Virus Warnings on: January 06, 2017, 12:51:05 PM
Seems like there should be a Filtering Industry false positive reporting process -- a clearing house sort of thing. My employer's IT could not even figure out where the filtering was happening .

There is probably an internet protocol for returning data about filtered content that is being disregard ed.

I hope they fix things before it gets worse.

--Justin
13  General Category / Virus Warnings / Re: Virus Warnings on: January 05, 2017, 05:01:39 PM
Heh. My employer's services wouldn't let gearotic. com through the layers of "protectio n". I put in a trouble ticket and slowly discovere d that no one at my firm knew how the network security worked, and that no one working for their security providers knew how it worked. There were multiple onsite visits and escalatio ns, and multiple declarati ons of "we fixed it", but no, they didn't. They tried to close the ticket "quietly" without resolutio n a couple times and I innocentl y reopened it. I finally had to conscious ly let it go. I was working from home in the evening or on my smartphon e.

This will probably fix itself as technolog y changes.

Not sure how you have your site set up, but I've had sites where I could have more than one domain pointing to the same content -- you could have a "short term fix" domain for people who are having trouble with their security.

--Justin
14  General Category / Gear Discussions / Re: I would like to make a planetary gear with inner gears and center gear on: December 08, 2016, 04:06:23 PM
Davarch,
If you sketch out your gears, you'll see that the diameter of the planetary gear is equal to the radius (half the diameter) of the ring gear minus the radius (half the diameter) of the sun gear:

P = R/2 - S/2

Since the number of teeth around the circumfer ence of gears with the same module is proportio nal to the diameters of those gears, you can use the tooth count to get the size of your planetary gear:

P = 72/2 - 16/2 = 28

It's nice that you wound up with a whole number of teeth -- You must have a plan!

I'm no expert at Gearotic, but I attached a gth...
--Justin
15  General Category / Support and Bug Reports / Re: Recording animations fails -- Error Found: 1667 on: November 20, 2016, 01:28:27 AM
Bill,
Thanks for the tip on camstudio .... BUT, my system's antimalwa re (panda) did not like it...
I hope your system is okay!
--Justin
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