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Neil Pabia
02-27-2012, 5:17 PM
I have been in contact with several people that wanted a rotary in the style that a scam artist was making for sale. I think that with the people that are on this forum, working together we can design a simple rotary that can be built inexpensively and used. I was thinking about starting with the stock Epilog motor and gears just to keep this as simple as possible. I have a machinist working with me when he has free time and truly believe that we can do this easily. Anyone want to help out with this, it would be appreciated.

Gary Hair
02-27-2012, 6:38 PM
What kind of help do you need? I have a rotary fixture for my GCC laser but will need one for the rotary engraver I am building. I'll be using steppers, not sure what you'll use for yours.

Email me directly if you want. garyhair at comcast dot net

Gary

Glen Monaghan
02-27-2012, 8:15 PM
What sort of help, Neil?

As I've said before, I'm not skilled on the mechanical engineering end of things, but the basic chuck-style rotary for an Epilog only has to have the chuck, some sort of mating threaded shaft, suitable bearings and support, a stepper that is compatible with their driver, and a 6:1 gearing to connect the stepper shaft to the chuck shaft.

From my novice point of view, the "suitable bearings and support" is the only problem. Take your pick of micro chucks and price ranges (which seem to cluster based on whether you can live with 2 keys or insist on a single key to operate the jaws). Apparently the chucks use either 1x8 or .75x16 thread connections, and because we aren't spinning them at 100's/1000's of RPM, we don't need a heavy, precision, expensive lathe spindle; a quality bolt of the correct size/thread can be used. You can buy Epilog's steppers or get a custom wound motor as I did for much less, and the gears can either be purchased stock (probably have to get an adapter for the motor end) or you can cut your own with your laser.

But getting a good match between shaft and bearings seems like a bugger to me. So many choices of bearing types, sizes, styles, and the tolerances there are pretty critical, easy to either be too tight or too loose depending on the specific bearings and shafts despite what the specs say...

-Glen

Real Mercier
02-27-2012, 10:41 PM
Neil:

I would be interested in helping out. What kind of help wre you looking for?

Real Mercier

Joe Hillmann
02-28-2012, 10:50 AM
Would it be possible to mount a chuck to a piece of pipe (the same diameter as the wheels on the epilog rotary) and on the other end of the pipe put a weight that will weigh more than anything you plan to place in the chuck and the set the whole contraption on to the epilog rotary with the drive wheels on the pipe. It would then print everything upside down so you would have to mirror it up and down and because you can't program the print driver with the diameter you would have to stretch the image up and down based on the percentage of the diameter of the object to be engraved to the diameter of the pipe. So on screen the item would look very messed if it is much larger or smaller than 2 inches but would come out correct on the workpiece.

David McHenry
02-28-2012, 11:04 AM
Neil,
The gear ratio on the rotary Bill sent me is all wrong. I had to using 4.5 plus inches just to engrave 360 degree around a .5 dowel. What I foond out is at a 3/4 inch input into corell equalls 360 degree on the shaft of the stepper motor. How to get it to engrave to the same measurement is my issue. I have pics of the rotary I'll try and upload

David McHenry
02-28-2012, 11:05 AM
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Neil,
The gear ratio on the rotary Bill sent me is all wrong. I had to using 4.5 plus inches just to engrave 360 degree around a .5 dowel. What I foond out is at a 3/4 inch input into corell equalls 360 degree on the shaft of the stepper motor. How to get it to engrave to the same measurement is my issue. I have pics of the rotary I'll try and upload

Joe Hillmann
02-28-2012, 11:34 AM
Whatever it takes to engrave around a .5 inch dowel is exactly the same as it will take to engrave around a 10 inch diameter piece or any other size piece.

To make it engrave like you want it to you first have to figure out exactly what size you need to make it engrave one full turn. Lets say that it is 4.5 inches.

So you make a page layout that is 4.5 inches tall and as wide as your bed is.

On that same page you make a square that is the same size as the cercumferance as your work piece.

Layout your work inside of that square the height of that square is the size of the entire way around your work piece.

Once you have the piece all laid out select the square and everything inside of it and make stretch or shrink it so it is 4.5 inches tall and as wide as your bed is.

Center this in you page layout that is also 4.5 inches tall and as wide as your bed.

Get rid of the rectangle or change its color so it won't print.

Now everything will look real stretched out or bunched up depending on the size of the work piece but when you engrave it it will be right.

Once it engraves if the piece is backwards you can either rewire the stepper motor or mirror the image up and down but not left to right to flip it around.


I would like to also point out the problem isn't the gear ratio. That has nothing to do with it. The problem is the epilog rotary and print drive are friction drive on the outer rim so all the print driver cares is if the wheels turn one inch then the workpiece must have turned one inch as well. With a chuck driven set up the driver is still thinking that all it needs to do is turn it one inch to turn the part one inch, what it really needs to do is ask you the diameter of the part, figure out the circumfrance and then figure out how much each step of the motor will move the work piece a given distance based on its distance from center.

Since the epilog driver isn't designed for that you could either write a program that will allow it to do that or you can cheat and trick the driver into thinking it is working correctly by adjusting your image like I just described.

Joe Hillmann
02-28-2012, 11:58 AM
If there is anyone nearby me (Cameron, WI) with an epilog laser with an epilog rotary who wants to build a rotary with a chuck let me know. I am pretty sure we could build one as an add on for the stranded epilog rotary for less then $100 then post the plans and how to use it so anyone here can build one.


edit: And if you wanted to build one with a jamb type chuck like universals use it could be built for less then $20.

David McHenry
02-28-2012, 3:11 PM
Whatever it takes to engrave around a .5 inch dowel is exactly the same as it will take to engrave around a 10 inch diameter piece or any other size piece.

To make it engrave like you want it to you first have to figure out exactly what size you need to make it engrave one full turn. Lets say that it is 4.5 inches.

So you make a page layout that is 4.5 inches tall and as wide as your bed is.

On that same page you make a square that is the same size as the cercumferance as your work piece.

Layout your work inside of that square the height of that square is the size of the entire way around your work piece.

Once you have the piece all laid out select the square and everything inside of it and make stretch or shrink it so it is 4.5 inches tall and as wide as your bed is.

Center this in you page layout that is also 4.5 inches tall and as wide as your bed.

Get rid of the rectangle or change its color so it won't print.

Now everything will look real stretched out or bunched up depending on the size of the work piece but when you engrave it it will be right.

Once it engraves if the piece is backwards you can either rewire the stepper motor or mirror the image up and down but not left to right to flip it around.


I would like to also point out the problem isn't the gear ratio. That has nothing to do with it. The problem is the epilog rotary and print drive are friction drive on the outer rim so all the print driver cares is if the wheels turn one inch then the workpiece must have turned one inch as well. With a chuck driven set up the driver is still thinking that all it needs to do is turn it one inch to turn the part one inch, what it really needs to do is ask you the diameter of the part, figure out the circumfrance and then figure out how much each step of the motor will move the work piece a given distance based on its distance from center.

Since the epilog driver isn't designed for that you could either write a program that will allow it to do that or you can cheat and trick the driver into thinking it is working correctly by adjusting your image like I just described.


I think I understand. Basically the diameter of the objects do not matter because of the chuck setup. Whatever I am going to engrave has to be 4.5 inches to engrave 360 degrees and 2.75 inches to engrave 180? I was think the gear ratio was wrong but I did not take into account epilogs driver is built for the epilog rotary. I do have the gear sizes. A 20 tooth was on the stepper and a 130 on the chuck. But since I have broken the 130 tooth maybe there is a way to get an even number to use as a measurment. I think I'm going to try and tack the gear back on and get an accurate measurement for 360 degree using 20 to 130 gears. If you look at the pics I posted you can see the 130 gear is too large, so large that it get in the way. I do think the right way to go is to measure the diameter but at this point I'm already to far along to change it.

Joe Hillmann
02-28-2012, 3:23 PM
As far as the 130 gear being in the way what is the diameter of the gear and what is the focal length of you lens, and do you have air assist on you laser? If you have air assist on it could you remove it to give you more clearance? also could you flip the rotary around so the head is pushed under the Y axis track so it is completely out of the way so the lens never has to go above it?

mark anizan
02-28-2012, 6:04 PM
Dave looking at your pictures yours has a different chuck then mine does.Mine has a Sherline mini chuck clears the stepper motor ok.I just have to find one of the drive gears to replace mine as its drilled off center.
mark

David McHenry
02-29-2012, 4:45 PM
Dave looking at your pictures yours has a different chuck then mine does.Mine has a Sherline mini chuck clears the stepper motor ok.I just have to find one of the drive gears to replace mine as its drilled off center.
mark

I thought so Mark. When I received it it was bigger than I thought. Because there was no back plate on the rotary I tightned it down with locktite and now I cannot it get off. I thought about getting a smaller chuck but if I cant get it off I guess I'll put a spacer between the motor and mount and get a longer belt. If I can get it off I'll buy the size you have and move this to my wood lathe. My plan was to share the chuck between the lathe and rotary but I just can get the thing off.