[RedskinsJBS]

After lurking for many weeks, taking is as much as one can in that amount of time, I have finally decided to release my current router design to be berated by all who dwell in the 'zone!

I have had the dream of building a large scale CNC device for years, but I have yet to be willing to take the step and actually build one. Discovering the 8020 design route has been an immense push in actually making me pull the trigger.

I come from the RepRap crowd. I helped design the first of the RepRaps, the Darwin (or was it the machine that built the Darwin that was the first of the RepRaps? Oh the chicken and egg odyssey persists...)

It was a few years ago now, but I once was even able to give a presentation about the subject and speak like I knew something...

Make: Online : Attention Capital Makers!

Since then many things have clouded my CNC vision, but do not worry for I have come back to the enlightened path! (Or maybe my wallet will begin to be enlightened, but I'll take whatever I can get).

Ok, enough jibber jabber, on to the machine!

My Dad has graciously allowed me to use the small store-room / workroom in his basement as the location to build my machine. I think that he did this so that he could play with it when I am not around. I go to school just a few miles from home, so I can be there whenever I like.

I originally wanted a machine that could make use of those 'handy panels' that they sell at the big home improvement stores. The downside to that sort of machine is that I would have to pay a premium for the smaller boards which, quite frankly, is silly. When my Dad told me that I could use the workshop, I immediately decided that this machine needed to scale. And scale it did. I enlarged the machine to a nominal 8' x 2' cutting area. (I think that it is actually closer to 110" x 26") This way I could make my own 'handy panels' by simply ripping a standard sheet of plywood in half.

After settling on the target dimensions of the machine and that I wanted to use 8020 as my primary build structure, I started lurking around here to find out how others had approached their builds.

The builds that caught my eye were CarveOne's now MASSIVE Steel R$P Gantry machine; Senna's 8020 ErectorSet Router; Arbo's 24" x 80" Router; And finally jsantos' 8' x 5' Router.

I read all of the build logs all the way through (yes, all 40 something pages of CarveOne's build log too) and then decided to put pen to paper and see what I came up with. Maybe some of the vast amount of experience in these build logs (or at least the mistakes that their creators divulged) would rub off on me and let me design a winning design.

From these build logs I discovered Ahren at CNCRouterParts.com and his amazing lineup of 8020 compatible gear. His products really do look nice. As a result of the look of quality and ease of use of his products, I decided to use his linear carriages coupled with his rack and pinion as the primary linear motion drives of my machine.

So, without further ado (and so I can get some sleep), here is the table of my machine. I'm sorry that I don't have the gantry designed yet, but I am as of now without a working model of Ahren's Carriages. I'm designing the machine in SolidWorks, and I am having trouble importing the files on Ahren's website into my program.

So, if anyone has a SolidWorks compatible file for Ahren's linear Carriages and they could post it here, that would be awesome!

Oh! And if you could please tell me where to alter my machine so that it will actually work and not simply fall apart when I turn it on, that would also be quite awesome!

[CarveOne]

Congratulations on getting started on your machine, and thanks for the compliments. You will get plenty of help and comments here. Sometimes more than you may be able to handle.

One advantage of the 50" width of cut on my machine is that I don't need to use the table saw so much anymore. It can sever cut a full sheet of MDF with simple keyboard jogs. Making yours wider (if you have the space) will cost more but is well worth it in the long run. I will rarely, if ever, need the extra 4' length over the full 8' sheet capacity, but the cost was negligible, and there is a nice built-in 4'x4' worktable on the end of the machine that I use for that purpose quite a lot.

Good luck with your build. Ahren's site has CAD drawings of the carriages and R&P drives that you will find to be useful during your build.

CarveOne

[RedskinsJBS]

Okay! Revision 1 of my design is ready!

The first photo is an overall view of the machine. The Axis movement dimensions are 111" x 28.75" x 8.5". So with safety margins, that gives me a cutting area of 109.5" x 27.25" x 7.75"! The machine's operating external dimensions (room for the motors to move etc.) are 120" x 50" x 22"

The table needed to fit in a very small room in my Dad's basement. The room used to be where the coal was stored to heat the house, and it has since been converted into a sudo-workroom / storage area. The room dimensions are 13' x 7.25' with a 6' ceiling. The machine (I will now refer to it as Rex2... just keeping with a theme even if I didn't stay with that girlfriend) is actually a little larger than I originally mapped out the space for, but I think that I can live with that. If not, altering the Y axis dimension is as simple as undoing a bunch of bolts and sliding the two X rails closer to each other.

Rex2 uses 1530, 3030, and 3060 profiles in it's construction. I would have used more 3060 if it weren't so darn expensive! With this design there is a total of 12" of it, which amounts to about 15$ on eBay... I think that I can handle that.

The X axis rails are 3030 with 4" x 1/4" CRS. All of the cross pieces in the table are 1530 extrusion cut to 39.75". This way I can get 3 of them out of a 120" rail (Which is the length that I would be ordering because of my two X rails). There are 9 stringers total, which means that I will use 3 120" 1530 extrusions in the table.


The second and third photos depict the clearances available in the gantry. I cantilevered the 3030 crosspiece on the 3060 supports and if gave me another ~7" of usable travel in the Y direction. This cantilever reduces the rigidity of the machine, but I don't think that it will be by much. To stiffen the gantry further, and fill the void left by the 3030, I added a piece of 1530 and a bunch of various types of gussets and joining fixtures.

One day I would like to create some sort of 'H' connector that would be used to fix two extrusions that are parallel to each other together. It would slide inside of two adjacent slots and would be able to be tightened through and access hole drilled in the extrusion. Maybe something like exists, but I haven't found it yet.


Finally, the last photo simply shows how the Z rail can now touch the X-rail; which is the most possible travel out of a machine of this design base.

Any input would be very much appreciated. This is my first real attempt at designing a large scale CNC machine of some sort. By no means is this design set in stone, so please feel free to suggest any improvements that I could make to it. The success of Rex2 is depending on your input!

[RedskinsJBS]

CarveOne,

I would love to have a machine capable of a cutting a full 4' x 8' sheet of plywood, but the room where the machine is going isn't even 8' wide itself. Maybe when I move in to a house of my own, I'll be able to make enough room for a 'full size' machine.

I can tell you that this room will still be packed! It will house both the original Rex RepRap Darwin and the new Rex2 wood router and maybe even a third PCB -only milling machine (I have probably 20 small steppers and various motor controllers that are begging to be made in to something).

[CarveOne]

Well, you do what you have the space for then. It gives you the CNC experience while you wait for the opportunity to make it larger or build a larger new one later.

Keep in mind that Ahren's carriages need 1" of rail extending off of each side of the extrusion width you shoose. You can use up to a 2" extrusion width for a 4" wide rail. Also, the center of the middle bearings to each edge of the carriage block is wider on one side versus the other side. You will need to decide which way you want to mount them and make all other parts fit together based on that decision.

Drawing it in a CAD program will help you deal with that.

CarveOne

[ahren]

Carveone,

That's not quite right -- you only need 1/2" of steel overhang on each side of the extrusion for the carriages. This is in fact the required spacing for the R&P to bolt on as shown in the video on our site. It can be done in other ways, but requires additional hardware.

As to the unequal length from the center bearings, there is one face that is intended as the mounting face for a plate or cross member. Jay has this modeled correctly in his schematic.

I need to update the carriage step files again -- there is a little more clearance than is shown now that we have moved to hex head bolts instead of the button heads. This also allows adjustment of the carriages in place, whereas with the button heads you had to remove the carriages from the rail, which was kind of a pain.

Jay, the only thing I might change is to make the connections between your bottom pieces and the long rails into butt joints with tapped ends -- more drilling involved for access holes, but this isn't too hard, and will stiffen your machine immensely. Otherwise, looking good!

Ahren
CNCRouterParts

[RedskinsJBS]

Jay, the only thing I might change is to make the connections between your bottom pieces and the long rails into butt joints with tapped ends -- more drilling involved for access holes, but this isn't too hard, and will stiffen your machine immensely. Otherwise, looking good!

Ahren
CNCRouterParts

Ahren,

I agree with you completely. Butt joints and tapped ends would be much stronger than the compression fitting that I am using. However, knowing what I know about myself, I don't trust myself to make 9 cuts of very equal length and drill the many holes in precisely the right places as well. I'm just too much of a spaz to be that accurate.

So I think that I'll live with less theoretical accuracy if I gain more real - life accuracy.

Maybe when I gain some sort of machining skill and experience, I'll rebuild the table to be stiffer.

It seems like evolving machines are much more common on this site than single-time builds. And I don't mind being a part of that group at all.

[ahren]

Jay,

You make a fair point, but keep in mind that a) the cuts can be made the same length with a nice hard stop setup for your mitre saw (or you can buy them cut to length from 8020), b) the horizontal rails on the top can be adjusted somewhat for inaccuracies, and c) the holes you are drilling are just access holes for an allen wrench to get through, so they can be off substantially as well. Either way will work, but having built tables both ways, I can tell you it's nice to have that rigidity, and there's no time like the present to start honing your craftsmanship

Best regards,

Ahren
CNCRouterParts

[RedskinsJBS]

I was talking with my Dad tonight about the design of Rex2 and he had what I think is a brilliant idea. He said that instead of a gas spring to counter-balance the Z-axis weight, I should use a constant force spring.

I'm sure that this idea has been mentioned here before, but it was news to me. And they are cheap too! Well, kind of...

This one from McMaster is under $10

McMaster-Carr

The issue with it is that it only has a cycle life of 4000 repetitions.

I'm not sure if I am allowed to fudge that number, but for $20 I am sure willing to try.


I know that it may be a bit too early to be thinking about how to correct a Z-axis that loses steps, but I would rather be prepared than disappointed.

I also plan on using a monster of a router, the Porter Cable 7518 3 1/4 hp on sale at woodcraft.com. (Thanks Carve One)!

Just thought that it was a brilliant idea... even if my Dad had to run downstairs and get one of my wind-up toy cars to demonstrate the spring to me!

[CarveOne]

Yes, of course you are right. I just went out and looked. My memory is not good. I have 1" overhang on mine but there is a little over 1/2" of clearance to the steel box tube they are mounted to. At one time I had the Y carriages mounted so that the pinion drive mounting plate was against the set screw side of the carriages with oversize holes in the plate to allow set screw clearance and for access to the set screws. I changed the carriages around the last time I rebuilt the gantry, so now they are all mounted correctly.

Either way can work if you really need it to.

CarveOne

[CarveOne]

The Ryobi 1.5hp router I have been using weighs 4.5 pounds, the Hitachi M12VC weighs 6 pounds, and the PC7518 weighs 11 pounds. I will have problems with the weight as well. Haven't really given that much thought to the weight issues with the heavier routers. The anti-backlash nut will wear faster, and thrust washers will become necessary. May even need a larger motor on the Z axis.

CarveOne

[RedskinsJBS]

I got around to measuring the workroom where Rex2 will be residing. I drew it up in CAD just to make sure that everything would fit and it seems like it will be comfortable enough. The only issue is going to be maintenance on the backside of the machine, but I think that I have a solution for that.

I had to draw up the whole room as well as the cabinets and ceiling outside of the room just so that I could be sure that the pieces of Rex2 would actually fit and go in to the room.

Just a quick update. I think that this week I may begin my purchasing of materials. I still have more cleaning to do in the workroom, as well as some dismantling of shelves and whatnot; but that can all be done while my parts are in the mail and on the trucks.

This is getting exciting. Its really unbelievable being able to 'see' what the work room will look like before I ever touch a part for Rex2.

More updates to come!

[CarveOne]

When I started construction of my steel frame I allowed 36" from the back wall and right end wall to the machine. A step motor sticks into that space toward the back wall. I was expecting to store cut-off MDF and plywood against the wall. The walking space is now down to 18" or 20" inches at times, but it works ok for me. If the machine is cutting something I just have to be more careful of the moving parts. Don't leave shirt tails or other loose clothing hanging out or they will get caught in a pinion drive and I guarantee that you won't find an e-stop button fast enough.

Sometimes you will want to go around the machine with a vacuum hose cleaning up dust and debris that the dust shoe doesn't contain, pick up parts as they are profiled or just look at the cutting progress.

I had to do all of my visualizing with an old-skool tape measure. Nice work.

CarveOne

[RedskinsJBS]

CarveOne-

Giving Rex2 ample clearance around the sides adjacent to the wall (~4"), I am left with a walkway that is just under 36". I know that once I get everything installed in the room, this distance is most likely going to shrink even more. But I am young and have a few years experience playing halfback on my high school football team; so hopefully I'll be agile enough to hit the E-Stop button.

Thinking about it, I should probably include multiple E-stop buttons on this machine. I'm thinking one on either end on the wall and probably one in the middle. That way, any E-stop button is always at an arm's length.

As far as loading and unloading material, my current plan is to just climb all over the machine when clamping the backside of large pieces. I may devise some sort of trick clamping situation, but I think that should be left to be thought out once Rex2 is built.

The cabinet base underneath Rex2 was simply a quick mock-up of the overall dimensions of the base that will be going there. I'll change around the orientation and dimensions of the shelves to suit the various materials that I will be cutting. For the very large pieces of material (ie full sheet plywood), they will be stored out in the garage. My Dad already has a pretty good solution to storing that stuff out of the way, so there is no need to try to improve upon a working system.

Also, I go to school about 2 miles from a big box home improvement store and I pass another one every day I go to work. So if I need some plywood, I can simply buy it when I need it.

[RedskinsJBS]

Either today or tomorrow I am going to order the large lengths of 8020 that I need to construct Rex2.

What I am wondering is what sort of saw blade should I use in my circular saw to cut the aluminum? Should I use like a 60-tooth laminate blade, or one of those abrasive disc blades?

Thanks in advance (whoever)

Jay

[CarveOne]

The senario I warned about almost happened to me and is why I mentioned it. My only e-stop was 6' away on the other side of the machine. When you are trying to get your clothes free of being sucked into the moving gantry your best hope is that the machine jams tight before anything serious happens to you. Getting free of it is the first natural response, not looking for the nearest e-stop.

People use a carbide toothed blade in a miter saw, but I don't remember which blade has been recommended. An abrasive cut-off disk will only clog up with melted aluminum in mere seconds. Using a table saw may have serious kickback issues and I wouldn't recommend it myself. If a sliding cradle is used on the table saw it may work fine.

CarveOne

[RedskinsJBS]

I tend to like the shirts that I wear. And I enjoy being injury free. So I am open to any and every safety suggestion possible.

For the past couple of years I have been working on some classic cars as my hobby (most BMW 2002s and Opel GTs, but a triumph TR3 & TR6 as well as an MGA were thrown in there as well) and whenever there was a rush to finish an installation, it seemed like personal safety was the first thing to get dumped. Injuries and broken parts were the only result from that type of decision.

I am trying to take my lessons learned from my car hobby and apply them to my CNC machine in any way that fits. 3 E-stop buttons versus just 1 seems like the right track. I *should* technically never be more then 3 1/2 ft from an E-stop with that sort of setup.

I was also thinking about placing a guard that ran outside of the motor along the table. Even if the gantry isn't moving, walking in to the pointy end of a stepper motor never feels very good.

I also plan on having an automatic dust collection system. This should both keep the airborn dust down and prevent me from having to stand close to the machine while it is moving because I have to hold the vacuum hose right next to the endmill.

Again, any other 'life experience' is much appreciated. I am simply working in hypotheticals right now, so having someone with experience who has made the mistakes or had the foresight to avoid them is very useful to me.

[CarveOne]

I still just have just one e-stop at present but will need to add more. A 12' long table will need a few.

Hmmm, I just had the idea that I can take my wireless mouse with me around the table and try to hit the stop icon on the Mach3 screen from anywhere around the table in a hurry to see if that works.

CarveOne

[RedskinsJBS]

Today I set on getting the workroom prepared for a massive CNC router that will soon fill it.

First on the list of things to get done: reverse the direction the door swings. If I were to keep the door swinging the way it did, it would be impossible to bring the 10ft pieces of 8020 that make up the X-axis of Rex2 in to the workroom.

I didn't bring any of my tools with me, so I was forced to use my Dad's. He is obsessed with 'building character' (or so he says), which is why he insists on keeping only hand tools in this house! (He actually is out of town this weekend and he brought all of his power tools with him.) It worked out alright. I only had to flip the hinges on the door and chisel out new mortises for the hinges and strike on the opposite sides of the door jamb. The whole process took a little over an hour.

While working on the door I noticed something that I had overlooked in the original drawing of my plan.

The workroom actually used to be a storage room for coal; and because coal is very heavy, the walls were poured with an extra re-enforcing layer that stands 44" off the floor. This waist-wall as I like to call it is 6" wide and essentially reduces the footprint of the room from 7' x 13' to a measly 6' x 12'!

The issue that arrises is that Rex2 with all of its motors and doohickeys is 49.5" wide, so 51" for safety. That leaves just 23" for a walkway next to the machine.

CarveOne mentioned earlier that I should worry about getting my t-shirt caught in the R&P, but now I am worried about being clocked in the hip by a rapid-moving Gantry that weighs 70 lbs!

I think that I'll have to make a rule that if the machine on, there will be no walking permitted next to it. I'll have to paint a yellow line outside the door as a cautionary measure.

I have some photos of the door before and after (I only remembered to take a before photo after I had removed the door from it's hinges, but its propped up in the orientation that it used to be in.)

I also re-drew my plan with the waist-wall added to the picture. You'll see what I mean about a tight squeeze. Good thing I'm young, right?

More to come!

[RedskinsJBS]

Oh! And I almost forgot to mention that I made the first purchase for the router...

I bought one of Val and Roman's Super-PID motor controllers. I know that I don't yet have a machine to mount them to, but the gadget is too cool to pass up.

I did order a 'modified' version because I plan on running the Porter Cable 7518 as my main 'spindle'.

Hopefully this whole shebang comes together soon. As you can see in one of the photos above, I still need to build some cabinets so that I can clear out the workroom. This is going to be a long week...

EDIT: Speak of the devil! As soon as I finished typing this post the doorbell rang, and guess what? It was my Super-PID arriving from Australia! And I have to say, everything is Super when dealing with these guys. I happened to have a very nice postman deliver the package... which is Super. And the parts were very well wrapped... which is Super. AND the parts look to be of a very high quality... which is Super!

I can't wait to test this out on some old universal motors that I have laying around. I've created a collection of shredders, weed wackers, and various other universal motor devices over the years and I can finally put them to good use!

Ok, that is all.