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4th axis

Re: 4th axis

Postby boelle1 » Fri Dec 17, 2010 1:56 pm

i got an idea for this... just need to think it through

it would involve turning the dust collection attachment so vacum hose is in front of the router an not on the side as now....
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Re: 4th axis

Postby boelle1 » Fri Dec 17, 2010 3:36 pm

what i had in mind was 2 disc's glued together and one of them have a grove where a length of chain can fit... this combo is bolted to where the router holder are... the combo also need two bolts sticking out, one at 90 degrees from the top and one at 270 degress... in the center another bolt..

then another combo but without a groove.... it has to have 2 slots close to the edge going from like 10 degrees after the top to 10 degress before the buttom and then again 10 degrees after the buttom and stop 10 degress before top... the 2 bolts will go in the slots and the bolt in the center through a hole in the last combo....

between the combos 2 sheets of nylon like used on tents... 1 sheet glued to each combo... this allows the 2 disc's to rotate very easy.... on top of last disc another sheet...

on top of each bolt first one washer then a spring and another washer and lastly the nut... this should keep the 2 disc's together but still allow them 2 rotate... a short strip of sheet metal arround the 2 disc's could support them further.

on the outer disc the router holder attachment are bolted and of course a 4th stepper with a sprocket that runs on the chain in the inner disc

this should give "almost 90 degrees tilt....

hope this gives some ideas
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Re: 4th axis

Postby LegacyHeirloom » Sat Dec 18, 2010 5:37 pm

a 5th axis is possible to implement as well; a 5th axis could be used to adjust the work table from level to a taper for the work, thereby creating the possibility to perform tapered work as well as parallel work.
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Re: 4th axis

Postby LegacyHeirloom » Sat Dec 18, 2010 5:56 pm

andrewlscott wrote:The issue with doing what you want to do with your CNC machine is that you would need 5 axis'. Axis-A would rotate the router about the x axis and axis-B would rotate the router about the y axis. Totally doable (even with the gyro forces), but a pain to program unless you have a program that can handle 5-axis milling.The better setup for a 4th axis would be to mount the 4th axis on the cutting table and secure your material to the 4th axis. (Think of mounting an index-able lathe to your cutting table.) Heck, with the right bit you could even cut threads (or tapered threads such as NPT fittings...) with this setup. Think of taking all those profile steps and making them perpendicular to the 4th axis, get a small enough bit and you could get some really good resolution. I think that this would be far easier to program, but again, you would want to use a program that can handle 4-axis milling.Speaking to gyro forces, your angle grinder creates far more gyroscopic forces than a router would. This is due to the relatively big grinding disk that the motor is spinning. Take the disk off and then move the thing around and you will find it much easier. Or if you have a small router table, just turn the router on and pick the table up and rotate that around.



In adding a 4th & 5th axis for the purpose of having a turnable stock, with the tapered capabilities, one would be able to also do spirals as well as flutes or indexing as you mention.

For software writing and revisions, I would suggest using Microsoft Visual Basic w/macros and Microsoft Excel; thus writing the program using a program that uses a Q & A forum to to establish the preferences for the stock to be turned or milled.
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Re: 4th axis

Postby LegacyHeirloom » Sat Dec 18, 2010 5:59 pm

Awesomeness wrote:One question I've wondered about, is how hard would it be to add another axis to the system, so that the router could be tilted at an angle. I've never used a high power router for anything, but I wonder what the gyroscopic force consequences would be (especially if they are anything like my angle grinder).The reason I ask, is because the projects/ideas that got me interested in CAM were large 3D objects. Specifically, at the time, I was making a very complicated 3D costume, based on exaggerated video game character armor. I was making it by sculpting it in clay, making [expensive] molds, then casting them in plastic resin. The idea that struck me, was how absurd it was that I was trying to recreate things by hand that were already in 3D modeling files that I could extract from the game. I thought, "Wouldn't it be great if I could have a machine just print or machine these for me?" (You can see the project on my site, http://www.thekimblefamily.com)I started thinking about a medical CAT scan, and how it "sliced" you up. I figured I could just edit the models, slice them into board thicknesses, and CAM them out. Then it would be a simple matter of stacking them up and gluing them together. I remembered a 3D Darth Vader puzzle I had seen many years ago, that did exactly this. ( http://www.amazon.co.uk/Star-Wars-Darth ... B0009FZI5S )Of course, since then I think up a dozen more projects I could do with one of these machines. It's to the point now where I see it as an indispensible tool, I have to get as soon as it's possible.I've also thought about using one to do the same thing with 2" thick sheets of insulation foam, in order to build forms to make large fiberglass itmes (like a child's spaceship/racecar bed).If there was an extra axis, it could make ridiculously awesome 3D stuff all in one shot.



The main obstacle to adding one or two more axis would be to use a larger breakout board capable of handling at least an additional two axis.
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Re: 4th axis

Postby Awesomeness » Sat Dec 18, 2010 10:34 pm

LegacyHeirloom wrote:The main obstacle to adding one or two more axis would be to use a larger breakout board capable of handling at least an additional two axis.


For $10 and you can put another parallel port in the computer, and another $30-130 and you can add a second breakout board, or they make ones with more pinouts if you like. Why do you think it's the "main obstacle"?

My opinion is that the main obstacles would be making the pivot mechanisms small, rigid/strong, and accurate. It seems especially difficult without using expensive materials or custom machined components.
If you don’t have time to do it right, when will you have time to do it over?
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Re: 4th axis

Postby Kevin » Thu Mar 24, 2011 3:26 am

Shop bot's machine at the bottom of this page is pretty cute as a 5-axis proto. I like double lug pivots better, but they have a machine and I don't.
http://www.shopbottools.com/mProducts/3-d_work_v2.htm
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Re: 4th axis

Postby JimM » Fri Mar 25, 2011 4:38 am

There seem to be two approaches to 4/5 axis milling.

1. Move the cutter head
2. Move the workpiece

I don't personally see any way around needing some precision parts for type 1.
Also, I expect this type requires an extremely rigid frame.

However, this guy managed to roll his own 4th axis with a rotary table and tailstock as 5th axis.
http://www.youtube.com/watch?v=Kqt0tD5Q-YM&feature=mfu_in_order&list=UL
Notice the Porter Cable router?

This is an example of a more industrial type 1.
Obviously designed for 3D sculpting from the ground up.
Lots of Z, but look at the ceiling height.
http://www.youtube.com/watch?v=33GHes6-_wM

The type 2 looks much more DIY friendly.
http://www.youtube.com/watch?v=w0-tXDEvAqg&feature=mfu_in_order&list=UL

Design it as an add on, scale it up as required and cut the parts out of MDF/MDO on the Blackfoot.
Put the extra axes on for 3D work, take them off and you still have a Blackfoot.
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Re: 4th axis

Postby kaetamer » Sat Apr 02, 2011 9:52 am

Has there been any further development of the 4th axis addon? Seems like a great idea that died on the vine...

Also, I know it violates the DIY spirit, but would it be possible to add a pre-made 4th axis setup such as the Shopbot 6" Rotary Indexing Head or some other setup? Obviously this would require some engineering to get it mounted and I don't have enough experience to know whether the wiring could be made compatible. I assume any four axis software would be able to utilize the addon.

Yes, I know the cost is off the hook, but is it possible?

Thanks.
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Re: 4th axis

Postby Kevin » Fri Apr 08, 2011 2:39 am

I don't know what's on Patrick's plate, but building a 4th axis shouldn't be any harder than figuring out the first three. You'd need some sort of bearing supported head rather than linear rails. Tapered bearings don't cost too much, and a 6" rotating head wouldn't be too hard. Chain drive from a sprocket would be similar to the Blacktoe. The Formula SAE crowd get custom tooth count sprockets from Sprocket Specialists when a stock item won't do. If you only wanted to make small diameter parts, a drill chuck is a cheap and easy way to hold round stock. With less precise holding fixtures, you'd probably do like these machines do on 3-axis parts: chuck excess material and make sure to cnc cut the entire surface where you care about the profile. Cost would be a matter of how refined you were looking for.

For a polished on the doorstep item, you could probably just buy the shop-bot setup or similar, mount it on a Blacktoe, and connect it your own stepper motor driver. I don't think Mach3 should mind the brand as long as you tell it how many steps per degree of travel.
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