large 4x8 router for cutting foam boat plugs

[waterboy]

Well here we go, I’ve been watching the cnc zone for a while know and I finally have to do it, I’m going to build a router, well actually me and a friend are going to build it together. I’m a kayak and canoe builder by trade, and my friend has a very cool racing catamaran. I eventually would like to be able to cut a full size kayak plug around 21 feet long. But to start I think we are going to build a 4x8 table I can cut plugs in sections to start and if it goes well just build 2 more tables and bring the total length to 24 feet. So I guess I should just tell you what we are planning so far.

First we are going to use all servo motors curious as to what are good ones for a project this size, remember we are only going to be cutting foam and wood.

We have decided to go with BWC dual v tracks for all our axis. Four a couple reasons, first it is very affordable, second we are going to be working in a very dusty dirty environment.

We are not quite exactly sure what sort of drives we are going to use, but we are thinking rack and pinion for the x axis, and lead screws for the y, and z. Some one has suggest ball screws, but we think the environment will be to dirty for them. Any ways we are looking for advice on motors controllers, and cam programs. Also I’m posting pictures of an idea we had. I have seen a similar machine to what I’m talking about that has a very long spindal. This is because our hull’s are up to 12” deep so we need a lot of depth clearance from the router. I will post a picture of the one machine I have seen. My friend Ted had suggested we figure out if we could cant router on the z axis and cut one side at a time. Any ways here are some pics of what I’m talking about. My pc is down so I made this quick with photo shop, I hope to have a good rhino rendering to past this week of the whole machine for you guys to comment on. Any ways please feel free to give e suggestions and pick our project apart, we need it.
Aloha Ryan

[Carver]

There is no problem canting the router at all. Obviously keep the limits this imposes in mind when programing your cuts.

Your plans sound quite feasible. If you choose components based on budget, that is just a fact of life. But,, if you want to use ballscrews, don't worry about the dust you will produce. The makers of the ball nuts make very effecient wipers on them with just this in mind.

Keep us posted, sounds like fun project. Would love to see some of your hulls also.

Best of luck, PP

[waterboy]

here is a pic of one of my more recent design, tones and tones of measuring by hand lots of bondo and even more sweet and blood, shaping a plug the old way sucks i need to build this router thanks

[waterboy]

woops

[whiteriver]

I am in the process of building a 5 axis foam carver from a idea i got from here using a robot i got off ebay. I think it would work quite well for what you are doing. You could have pins in your floor just cut your part then move the router foward to the next zone. Then go around to the other side. Or just build two long ones. One for each side. You could run them at the same time. Check out the videos if you got broadband. You could do it with a mauall adjust router head. wouldn't need to spend the money for a tru 5 axis. Would be cheaper on the cam software also.

Donny

www.whiterivermfg.com

[Carver]

Hi Donny, Ryan,

I do a fair bit of architectural carving for other carvers and manufacturers. Right now I am doing some carving on 32' beams (12" x 18") on a machine with only a 10' bed. Registering the product and sliding it down the x axis really isn't much trouble. Because of the black clay soil where I live, depending on the concrete slab to be in the same place or stable for two consecutive days is suicide. I have done a cople of boat plugs in sections and have not had any problems at all. It is plenty easy in Rhino to simple add alignment keyways on each part and the foam is very stable and easy to work with.

Nice hull, looks like fun, Phill

[waterboy]

hey guys any sugestion on servos for this rig

[ynneb]

hey guys any sugestion on servos for this rig

Well I suggest you make your router the full size from the word go.
You can get away with it been long and narrow since that is the nature of your boats.
It is possible to make your router very cheap by using v bearings on angle iron. There is a member on this forum who sells nice servos that would be more than adequate for your machine. Just look up kevincnc and email him.
I also recommend Rutex drives for your project.

Timing belt drive would be the most economical drive for a table the length you are thinking about.

I dont know how easy the gcode would be to make but i recon you could get away with machineing on a X,Z and A axis. That would mean the router traveled along the length of the boat and up and down, and the boat rotated on the A axis too. I am sure others would be able to tell you if that was practical.

[jcc3inc]

Dear Sir,

If you are going to machine something 20+ feet long,why not consider rack and pinion for the drives. It is essentially inelastic compared to a stretched belt, easy to install, and with 20 degree pressure angle rack and pinion it will operate smoothly. To eliminate the backlask, spring load the pinion into the rack. We used to build large plasma and oxyfuel machines with rack and pinion drives on all.

Regards,
Jack C.

[whiteriver]

I'm in the process of designing a large foam carver and was wondering about useing a rack for the Z axis. What is ones opinion on that? It would have 8' to 9' of travel. Slide on thk or nsk slides. Be powered by a 2600 oz/in stepper.. The weight would be under 500lbs for what it would be lifting.
Would a rack and pinion be sutiable for that. I always see them on horazontals.
Any more info about spring loading the pinion. I have a rack on my X axis on another machine and it could use a spring loaded pinion. It has about 0.02" backlash. I think if it had even pressure across the 11' of travel if would have less backlash.

Donny

www.whiterivermfg.com

[buscht]

Donny, you should counterbalance the weight of the Z axis. There is no need to force the motor to pull up a 500 lb load.
I would think that a rack and pinion would have the same results in whatever axis you use it,
T

[whiteriver]

I agree on the counter balance. I was gonna have a cable weight block system that would get the actuall weight moved close to zero. I just have never seen anyone use a rack in the Z so I figured there must be a reason why.

Donny