Finally got around to making the prototype after concept testing frame will be made from aluminum. Build cost $50 but found the inventables supplier for the nema 23 140oz. for $20. Now the hard part begins.
stepper can be found here NEMA23 140oz/in 2.8A Stepper Motor ¼” Single shaft (KL23H251-28-4A) |
https://www.youtube.com/watch?v=0KWHU2BL9kY&feature=youtu.be
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Looks good!
Thank you still a long way to go.
awesome!
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Cool. 
I gotta couple of questions Shane. I was thinking of doing this also.
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At 8 microsteps with a 200 step motor the angular resolution would be 0.225 degrees per step. Do you think this is accurate enough. I was think about going for a 3:1 or 6:1 reduction.
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GRBL doesn’t support rotary axis. I was thinking of switching to TinyG. What are you using?
Thanks!
Todd
I am using a 6:1 reduction on my rotary axis and it works great.
Well first off I will start by saying I have no clue what I am doing so resolution is a question I can not answer. I was just in the mood to go ahead and start prototyping my 4th axis that way it will be finished later down the road when I decide to switch to a 4 axis controller. At the moment the only thing I can really do with it is laser engraving and rounding stock with basic math takes care of creating a vector image that fits on the rotational plane without changing my stepper settings.
Doesn’t have to. With a program like Vcarve PRO you can substitute one of the X or Y axes as your rotary axis and work with a 3 axis controller (grbl).
I have thought about vcarve or try to see if gcode ripper works artcam also has this function and can be gotten for $45 a month
http://www.scorchworks.com/Gcoderipper/gcoderipper.html
The problem with using grbl with a rotary axis is the steps per mm must be recalculated for each piece of stock.
It will work, just have to redo the steps prior to each cut…I did it a few times.
I finally switched to the Gecko g540 which allows me to use my rotary axis properly…a rotary axis does not use linear movement (like grbl does) it moves the axis in degrees.
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Awesome! This really makes me feel that what I am working on is worth my time. After seeing this I feel my money will be better spent on software rather than adding 4th axis support. When I am happy with the design of my rotary and made into the final assembly in metal I am going to release the plans for the others to freely use as a low cost diy rotary for small items where no modifications to the xcarve other than adding a 4 pin plug on the y axis need to be done.
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Not sure this is necessary. I’m looking into it.
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Hi Larry,
Eric is correct. You can generate the code with VCarve to wrap the Y or X axis BUT your controller must support a rotary axis. I spent a lot of hours looking at this. If you think about linear distance on the rotary axis, the number of steps would be based on the diameter of the work piece (or more precisely the distance of the bit from the center of rotation). If you go and look at how Mach3 or TinyG is configured for a rotary axis it might make more sense to you. As a matter of fact, the TinyG firmware is a branch of GRBL. The main improvements were acceleration planning, the addition of rotary axis support, and support for 4 stepper motor drivers.
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I’ve even considered building a dedicated rotary axis carving machine, but I figure it’s just as much work as building a better CNC. I’m thinking of switching to TinyG because it is low cost and supports rotary axis. I’m just not sure if the stock X-Carve would support the diameter carvings I would like to do.
How big are you wanting to cut?
Shane I was not being critical but just wondering if you thought that resolution was enough to produce decent rotary carvings, but it sounds like you are still experimenting. I look forward to hearing how it works out for you. Thanks for sharing your design!
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Having looked at this for all of 10 minutes, I certainly will yield to better knowledge than I have.
I’m confused though. Since with a wrapped project in Vcarve PRO you can specify the Z origin to be the center of the axis and you specify the diameter of the cylinder it should be simple math to come up with the travel around the cylinder at any position of the mill end.
Since you have spent the time on this, I won’t spend anymore since I don’t have a rotary axis anyway.
so I am interested in this what you say would be the weight limit on material? I guess I mean the biggest thing that you could swing with that nema motor
and man!!! those tiki carvings is something that I want to make you wouldn’t happen to have any files that I can take a look at do you
you would be a legend!!