| Author |
Message |
    
bugmenot dillbert
Registered
Username: Soulvoid
Post Number: 7
Registered: 02-2007
| | Posted on Monday, March 12, 2007 - 12:59 pm: | 
|
Hi,
a typical surfboard shaper machine looks something like this www.kmsystemes.com or www.surfboardshapingmachine.com There are other machines out there built on the same architecture. There are other surfboard shaping machines that are more efficient and sturdier built, but in general they move the item to be cut (blank) instead of the cutter in the x direction and have a heavy bridge for the y and z of the cutter which is only moving short distances for one pass. The blank only weights a couple of pounds so moving it is no problem, however the footprint of the machines become large as cutting a 10' surfboard requires a 20' x footprint. That's out of the question for me. There are also some shopbot based machines used for cutting surfboards.
I think the machines such as kmsystemes and 3D motion are kind of flawed by hanging the cutter on only one side of the beam. Unless the beam is extremely rigid you get twist and inaccuracies. some of them compensate for this by using a heavy duty beam and powerful servo motors, some seems to just ignore the problem. Personally I like the mechmate better where the cutter is sitting between the beams of the gantry.
A good handshaper using a powerplaner can shape a 6' surfboard from a close tolerance blank in about 20 minutes, so speed of the machine is an issue. I know that some of the shaping machine do one 6'cutting pass in 7 seconds, but this is with servos. The foam is fairly soft (compared to wood) and cut fairly easily which helps. This will however be strictly a hobby machine in comparison aiming for on side of the board in 30-60min. I'm guessing the long beam of the surfboard shaping machines is to only make the lightest part move in the longest direction thus keeping speed high and ramping to an absolute minimum. Therefore I was thinking about making the gantry the longest axis to make the cutting length 9'6"-10'. I still would like to be able to cut plywood sheets so I would make the table 4' wide.
Is it possible without modifying the design considerably and still be able to cut wood? I'm worried about too much flex in the gantry beams with that length. The extra weight of the gantry should not be a huge problem, movement for the gantry will be max 16" pr. pass. If flex is a problem then an option might be to use a larger box section than 100x50, thicker walled(at the expense of added weight). |
Arthur Ransom
Registered
Username: Akransom
Post Number: 31
Registered: 09-2006
| | Posted on Monday, March 12, 2007 - 04:46 pm: |
|
Foam would be a piece of cake. Dimensions of the MechMate can be be drasticly changed. Long axis,Y, is the base and could easly go 50' by just adding legs to prevent sagging. With the gantry ( X width, Z up and down) able to do 4' wide speed would be limited by the quality of cut in the material. A 6' pass in 7 seconds is about 800 inches per minute of travel,IPM. I asume that the 800 IPM is the limit of the cutting tool and not the machine. The plans for the 4' wide machine width the Y axis extended to the length needed should be a perfect fit for you and capable of machining to at least .01" tolerances. One major factor in the strength,weight and mass of the gantry is that when the motor is told to move at 800 IPPM it attempts to do so IMMEDIATELY and when to stop and reverse direction it attempts to do it NOW! This creats a lot of force and strain on the machine. This problem is being addresed by Mach and based on their track record I would expect it to be resolved within a few months. All said and done the MechMate will match the speed of the other machines. |
|
General