Re: [Emc-users] CNC little hobber

[andy pugh]

On 2 October 2016 at 16:17,   wrote:
> I have looked at some gearing diagrams of gear hobbers and I noticed that a 
> 'differential' gear set was included. What does that actually do?

It is for helical gears, and is linked to the feed gears. (Also easy
to do with LinuxCNC and HAL)

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atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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Re: [Emc-users] CNC little hobber

[Dave Caroline]

The differential gears are nothing to do with prime but to add the
traverse into the equation and also to add a rotation for a helical.
I have a diagram of one at
http://www.collection.archivist.info/hobbing.html

then you can wind the hob back along its cut traverse and it remains "in gear"

Dave Caroline

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Re: [Emc-users] CNC little hobber

[richshoop]

c-users mailing list 
> Emc-users@lists.sourceforge.net 
> https://lists.sourceforge.net/lists/listinfo/emc-users 
> 




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Message: 2 
Date: Sat, 1 Oct 2016 23:36:46 +0100 
From: andy pugh <bodge...@gmail.com> 
Subject: Re: [Emc-users] CNC little hobber 
To: "Enhanced Machine Controller (EMC)" 
<emc-users@lists.sourceforge.net> 
Message-ID: 
<CAN1+YZXeuK7xZAMEh=3g5bax2muuhg+ih1dx1odm6pfo4r2...@mail.gmail.com> 
Content-Type: text/plain; charset=UTF-8 

On 1 October 2016 at 22:49, <richsh...@comcast.net> wrote: 
> OK, I know nothing about gear hobbing, but have seen that youtube video of 
> the little hobber, what kind of work would need to be done to build a cnc 
> version of such a machine? 

It's actually almost trivial with HAL. 

https://www.youtube.com/watch?v=ZhICrb0Tbn4 

-- 
atp 
"A motorcycle is a bicycle with a pandemonium attachment and is 
designed for the especial use of mechanical geniuses, daredevils and 
lunatics." 
? George Fitch, Atlanta Constitution Newspaper, 1916 



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Message: 3 
Date: Sat, 1 Oct 2016 17:45:45 -0500 
From: sam sokolik <sa...@empirescreen.com> 
Subject: Re: [Emc-users] Estimated time remaining 
To: "Enhanced Machine Controller (EMC)" 
<emc-users@lists.sourceforge.net> 
Message-ID: <ca6b8c5b-828f-a24b-f6a7-8b82adcf1...@empirescreen.com> 
Content-Type: text/plain; charset=windows-1252; format=flowed 

I was wondering if you could create an accurate estimate by creating a 
sim config with (now just thinking out loud) 1000 times the 
velocity/accelleraton and the feedrate override set to 1000%. You 
would run the program in sim - then multiply the time by 1000. (or 
whatever) 

I have not thought this through - and it might not be that simple... :) 

sam 

On 10/1/2016 5:27 PM, Danny Miller wrote: 
> The estimator DOES just use distance & feedrate, not acceleration. This 
> is effective for estimating 2D cuts but junk for 3D carving, which 
> hinges primarily on acceleration. 
> 
> There is no one effective "factor". I have 3D carvings which took 4x 
> longer than estimated, others 6x. If it is only a gentle slope then the 
> factor could be 1x, all for the same profile. 
> 
> When tuning a machine, you can reduce the axis max velocity in order to 
> increase the max acceleration, and this can in fact make the machine run 
> faster. Note an arbitrary multiplier factor would be useless for 
> tuning, as you need to know the actual effect of the parameter changes. 
> 
> But the feature I proposed- an ETA timer- I don't see how to do it, 
> because the required info isn't on the interface that I can find. 
> Specifically "total line count from the G-code" and "current line number 
> in the G-code". The concept would fail for sure on G-code bearing 
> subroutines but that's not a feature of any of the 3d carving I'm doing. 
> 
> The ETA-by-line-count would be inaccurate on 2D cutting, even without 
> subroutines, because there's no telling how long a vector is. A curved 
> cut can be 10 or 1000 lines but only take a second or two, while a 
> single straight line can be a long cutting time. 
> 
> Danny 
> 
> On 10/1/2016 8:39 AM, Todd Zuercher wrote: 
>> I suppose you might be able to make something like that. 
>> 
>> But I think I have a good idea for improving the run time estimator. Right 
>> now how does it work, does it just use the feed rates X distance to be 
>> traveled? What if it took that and added to it a factor(derived from the 
>> machines acceleration rate) X the number of lines in the file. 
>> 
>> - Original Message - 
>> From: dan...@austin.rr.com 
>> To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> 
>> Sent: Friday, September 30, 2016 11:30:51 PM 
>> Subject: [Emc-users] Estimated time remaining 
>> 
>> I am doing 3D carving, where the Properties analysis is regrettably useless 
>> for coming up with time estimates due to not taking into account the 
>> acceleration aspect of trajectory planning. 
>> 
>> I did install the cycle timer pvcp and it does certainly help. 
>> 
>> But one thing I noticed- these carvings are "mostly" consistent in how much 
>> time they're taking per-line. It would be accurate enough to be helpful to 
>> calculate: 
>> 
>> Time Remaining=(total # of gcode lines/gcode lines done so far)*cycletime so 
>> far 
>> 
>> Is there any way to do that? All I can see is access to "time". 
>> 
>> Danny 
>> 
>> --
>>  
>> Check out the vibrant tech commu

Re: [Emc-users] CNC little hobber

[Gene Heskett]

On Sunday 02 October 2016 03:02:20 Dave Caroline wrote:

> And I used Andy's info and cnc'd a Barber Colman hobbing machine
>
> http://www.collection.archivist.info/searchv13.php?searchstr=barber+co
>lman+pd
>
> Dave Caroline
>
I'm impressed.  Nice work Dave.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] CNC little hobber

[Gregg Eshelman]

Replacing all the gearing that interconnects the various axes with encoders and 
motors on each bit that spins.



 
  From: "richsh...@comcast.net" 
 To: emc-users@lists.sourceforge.net 
 Sent: Saturday, October 1, 2016 3:49 PM
 Subject: [Emc-users] CNC little hobber
   
OK, I know nothing about gear hobbing, but have seen that youtube video of the 
little hobber, what kind of work would need to be done to build a cnc version 
of such a machine?
   
 
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Re: [Emc-users] CNC little hobber

[Dave Caroline]

And I used Andy's info and cnc'd a Barber Colman hobbing machine

http://www.collection.archivist.info/searchv13.php?searchstr=barber+colman+pd

Dave Caroline

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Re: [Emc-users] CNC little hobber

[andy pugh]

On 1 October 2016 at 22:49,   wrote:
> OK, I know nothing about gear hobbing, but have seen that youtube video of 
> the little hobber, what kind of work would need to be done to build a cnc 
> version of such a machine?

It's actually almost trivial with HAL.

https://www.youtube.com/watch?v=ZhICrb0Tbn4

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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