Bob's Super Simple 4th Axis

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rungemach
Posts: 460
Joined: Mon Aug 02, 2010 8:24 am
Location: Sarasota, Florida

Re: Bob's Super Simple 4th Axis

Post by rungemach »

Thanks for posting this. Your solution is very pure and simple, the mark of a great design.
A great alternative to a costly 4th Axis.

Since you have a fixed ratio between the y travel and degrees that the workpiece turns, you should be able to calculate steps per degree and use true rotary axis software to drive this. ( as well as "wrapping" a linear file.)

Outstanding work. I feel the best feature of the Shark is the user group, and you folks remind me of that almost every day.

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Bob
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Joined: Sun Aug 08, 2010 3:35 pm

Re: Bob's Super Simple 4th Axis

Post by Bob »

Bob,
You have just given a good example of "teaching me how to use this thing".
Thank you.
Now I'm waiting for the wrapping tutorial.
Bob
"Focus"
Antonie Van Leeuwenhoek (Developer of the microscope.)

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Bob
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Joined: Sun Aug 08, 2010 3:35 pm

Re: Bob's Super Simple 4th Axis

Post by Bob »

When drilling the center holes in the ends of the work piece, I use this simple centering fixture.
Be careful if you use these files, I kept changing designs as I machined the fixture.
At least it will give you a rough idea of what I did.
center hole jig 1.21875 & 1.4375.crv
(207 KiB) Downloaded 1003 times
Bob
"Focus"
Antonie Van Leeuwenhoek (Developer of the microscope.)

Tim Owens
Posts: 361
Joined: Wed Jul 28, 2010 3:51 pm

Re: Bob's Super Simple 4th Axis

Post by Tim Owens »

Bob,

Very nice novel idea.
The only issue i see with this is of course you have to have it the 20 inch piece in there even if you are doing a small piece. The other might be an issue from having the the rack gearing on the bottom. If you have a lot of shaving coming off your cut it could clog the track. You could either put it upside down on the top of the gear (not as easy) or you can put a constant air on the track to prevent contamination by the shavings. (you can also enclose the ends)
Keep us posted how it works.
Thanks

Tim

BobA
Posts: 165
Joined: Fri Nov 05, 2010 10:01 am

Re: Bob's Super Simple 4th Axis

Post by BobA »

Bob

Do you know the pitch diameter of the gear?

I calculated by using measurements to be 2.39" pitch diameter and 7.51 circumference.
With the rack I measured .2453 between teeth and calculated using this measurement that you would need to travel 7.35" with a complete revolution of the gear.

So I would assume if you were machining a 2.5 diameter .050 deep you would have a 1/1 ratio on the Y axis dimensions. You said that x axis was not affected.

So, If you were machining a 1.25 diameter you would have a 1/2 ratio and would have to double the y axis dimensions.

Does that make sense?

Bob

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Bob
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Re: Bob's Super Simple 4th Axis

Post by Bob »

Tim Owens wrote:Bob,

Very nice novel idea.
The only issue i see with this is of course you have to have it the 20 inch piece in there even if you are doing a small piece. The other might be an issue from having the the rack gearing on the bottom. If you have a lot of shaving coming off your cut it could clog the track. You could either put it upside down on the top of the gear (not as easy) or you can put a constant air on the track to prevent contamination by the shavings. (you can also enclose the ends)
Keep us posted how it works.
Thanks

Tim
Hi Tim,
I agree with you that this device has limitations. However, it provides a good starting point for those of us who want to get an introduction to 4th axis work. When the limitations of this machine start to hinder creativity, it will be time to look for a more versatile solution. And, I know that you are developing an excellent answer to these limitations with your 4th axis at Next Wave.
Thank you for your helpful suggestions.
Bob
"Focus"
Antonie Van Leeuwenhoek (Developer of the microscope.)

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Bob
Posts: 1252
Joined: Sun Aug 08, 2010 3:35 pm

Re: Bob's Super Simple 4th Axis

Post by Bob »

BobA wrote:Bob

Do you know the pitch diameter of the gear?

I calculated by using measurements to be 2.39" pitch diameter and 7.51 circumference.
With the rack I measured .2453 between teeth and calculated using this measurement that you would need to travel 7.35" with a complete revolution of the gear.

So I would assume if you were machining a 2.5 diameter .050 deep you would have a 1/1 ratio on the Y axis dimensions. You said that x axis was not affected.

So, If you were machining a 1.25 diameter you would have a 1/2 ratio and would have to double the y axis dimensions.

Does that make sense?

Bob
Bob,
All this thinking is making my head hurt. You sound right...I arrived at my ratio by comparing circumfrences. A little trial and error also helps. When I was designing the machine, I knew that the different diameters would need to be taken into consideration. I estimated the change needed in Y and tried a sample. The second sample worked as planned.
With your experience, you will probably get it in one.
Bob
"Focus"
Antonie Van Leeuwenhoek (Developer of the microscope.)

bdboy8
Posts: 7
Joined: Mon Jun 25, 2012 11:25 am

Re: Bob's Super Simple 4th Axis

Post by bdboy8 »

Thank you Bob.You really put your talents in this .Great job.Thanks.

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Bob
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Re: Bob's Super Simple 4th Axis

Post by Bob »

You're welcome.
Has anyone tried this contraption yet?
Bob
"Focus"
Antonie Van Leeuwenhoek (Developer of the microscope.)

Eagle55
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Joined: Sun Nov 20, 2011 8:44 pm

Re: Bob's Super Simple 4th Axis

Post by Eagle55 »

I thought you did Bob Ha Ha Ha :lol:

Its on my list of things to do, but the list is long and distinguished :(

Roger
CNC Shark HD ~ Control Panel 2.0 ~ Windows 7 & XP
Located in West Tennessee near the Tennessee River
http://www.eaglecarver4.com

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