Bob's Super Simple 4th Axis

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EdThorne
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Re: Bob's Super Simple 4th Axis

Post by EdThorne »

Very nice. I like it. I still haven't gotten around to fabricating the 4th axis parts. Maybe I should start, soon. Aspire 8 seems to have provided additional support for handling these operations. Have any of you tried these features?

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NewAgent45
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Re: Bob's Super Simple 4th Axis

Post by NewAgent45 »

Hi Bob,

First time replying to a post with my phone. I'll be brief. Yes I do need to adjust the rack depending on material length. It is just a matter of loosening the three rack mounting bolts and sliding the rack in the T-slots in the spoilboard.

Thanks for your comments.

... Rod

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NewAgent45
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Re: Bob's Super Simple 4th Axis

Post by NewAgent45 »

Ed,

I'm not sure how 4th Axis support in Aspire 8 or the new version of VCarve Pro would help in the case of the "simple 4th Axis". Understand we have compromised the y drive ratio by use of the gears instead of using an additional stepper motor to drive the spindle. I would like to hear some input from those using the 4th Axis features. I looked at the wrapping Gadgets available for VCarve Pro 7.5 and I don't see how I could use them for this setup. The use of these gears is a mechanical change that the controller knows nothing about. This is why I documented those simple calculations in my post this morning.

Also any vectors you can easily draw based on a revolution are simple to do.

I have only been working with this stuff about a year and a half now. So my ears are open. In the mean time I'm having fun.

Have a great day!

.... Rod

EdThorne
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Re: Bob's Super Simple 4th Axis

Post by EdThorne »

Hi Rod, thank you for your reply. I haven't tried any of this. I'm just thinking out loud. Maybe one might be able to use the wrapping gadgets as follows. Create the correct diameter and length piece. Unwrap this and then create the 3D features. This may be wrapped for visualization and then unwrapped before creating the toolpaths. The wrap will always need to be around the x-axis. Now, the problem is scaling the y-axis correctly. This depends upon the gantry y-axis movement being scaled equivalent to the rotary axis movement. I seem to remember that the steps per unit distance may be changed in the Shark controller so that the linear and rotary movements may be equilibrated. This change would need to be made when using the simple 4th axis and then returned to its original value when normally using the gantry. Anyway, maybe there is something that I am missing that will prevent this from working. I have a problem visualizing complex carvings when unwrapped so this approach let's me see the wrapped final carving. Maybe?
Regards,
Ed

Another thought: Instead of changing the step profile through the Shark Controller, one could alter the diameter of the work-piece so that the rotational distance is forced to be equivalent to the linear y-axis displacement along the y-axis. I would like to visualize carving a human head using this approach. I'm not able to visualize this in unwrapped format.

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NewAgent45
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Re: Bob's Super Simple 4th Axis

Post by NewAgent45 »

Ed,

Obliviously you have a better grasp of the technical aspects of the “simple 4th Axis than I. As I understand I’m already taking the scaling problem into account. I’m sure there are some errors in my method. I am having fun with it and seeing results.

In my post of 3-15-2015 I documented the gear design and there is a drawing of the rack and pinion there. I learned that the pitch diameter of the pinion gear is the point where the material circumference is equal to linear y axis. I “simplify” by using the Pitch Dia. - Material Dia. Ratio for approximation. I recognize there is error during the carving process as the diameter decreases during the carving process. I’m recalculating this for each step in the carving process. So far this is working for the intended purpose of graphic art production. We don’t require tight tolerance work here.

I do welcome your discussion and please continue. I hope some others will join in too. I’m learning every day. That’s amazing in itself for and old retired dinosaur. My career in engineering was not mechanical and I have no machinist experience either. I did get some exposure from an old friend who was a tool and die maker and gunsmith. He departed a long time ago.

Out to my shop for some more fun.

Have a great weekend!

…….. Rod

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NewAgent45
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Re: Bob's Super Simple 4th Axis

Post by NewAgent45 »

Per Ed’s request I’m posting an update on my version of Bob’s Simple 4th accessory. I built this for a CNC Shark HD/Black diamond.

My antique style pepper grinder project tells most of the story. I created the grinder body profile in Sketch-up Pro. I also loaded a 3D model into 3D Machinist and scaled the model and created the toolpaths for the model. I used 3D Machinist instead of Cut3D because 3D Machinist allow you to unlock and separately scale x and y. Both the Sketch-up export and 3D Machinist files were imported into VCP.
Project Pictures:
4th Axis Pepper MIll turning.jpg
Pepper MIll 1.jpg
Pepper MIll 2.jpg
Have a great day!
...... Rod

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Bob
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Re: Bob's Super Simple 4th Axis

Post by Bob »

Rod,
Wow! Nice Job.
It certainly looks like you know what you're doing.
Bob

EdThorne
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Re: Bob's Super Simple 4th Axis

Post by EdThorne »

Rod, That if really fascistic. I've got to try Sketch up. It would seem like Bob's 4th axis could be used with the Probe. I have no artistic capabilities but even I can copy something. Maybe not well but ...

Thank you for sharing!
Ed

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NewAgent45
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Re: Bob's Super Simple 4th Axis

Post by NewAgent45 »

Ed,

There is a learning curve with SketchUp and you can try the "pro" version for 30 days after witch it reverts to the free version. You loose the export feature in the free version. There are some training videos that help. I believe 4. I recommend taking all 4 of them after installing the SketchUp application. I paused the video at intervals and tried to work through each part of the training.

The model I built was fairly simple as it was the "unwrapped" version. Basically half of the cross-section of the cylinder. So in SketchUp it looks like a piece of molding mill work where the end view is the cross-section.

At this point I have to cough-up the $590 to get the pro-features back.

There is another post dated Apr. 3 above where I discuss in more detail the pepper grinder. I really only added the finished pictures today.

Thanks for your interest.

...... Rod

EdThorne
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Re: Bob's Super Simple 4th Axis

Post by EdThorne »

Thank you, Rod. I may have to wait until I retire next year in order to have time. I'll also need to justify the expense. It looks interesting. I'll give it a try. I'm still learning Aspire. I started with no experience in cnc or CAD and have enjoyed the journey.
Ed

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