Hi everyone. I'm a long time lurker. I'm getting ready to place an order for everything needed to make an OX. I talked the local water jet guy and he recommended 3/16" over the 1/4" for the aluminum plates. He looked over the plans and did not think 1/4" was needed for this size of CNC router. Anyone using 3/16" plates. What do you guys think? Steve
If you don't mind, what is it going to cost for the material and his water jet services ((before I answer your question)?
Hi, in general with cnc a more stiff material is to be prefered. Unless you want to mill real slow your machine will tend to "wobble" if your mechanics are too weak. Milling with some speed will make your spindle change directions in an instant and , naturally quite often too. Together with cutting forces aditionally bending your z achsis you want all the stiffness you can get in your design. On all axes. That is the reason why most comercial availible machines weight more than you want to lift on your own and real pro machines weight tons. As every little "play", inacuracy .. adds up in the end, one should design for the best possible in a design. Starting from the "lowest" does not make sense - for me. So you simply cannot go wrong buying stiffer material. greets flo
@Steve123, The problem is there is no hard and fast data on exactly what minimum thickness is best to achieve the desired stiffness for the machine. How much stiffness required is also a function of what you intend to cut, the size of your system, and the weight of your router. What is known is that 3mm steel was not stiff enough (as noted by one user here on the forum) and that 6mm aluminum is stiff enough (as noted by many). So where does 3/16" aluminum fall? It is 38% stiffer than 3mm steel but only half as stiff as 6mm aluminum and 42% as stiff as 1/4" aluminum. So the answer to your question is...... maybe. Sorry but that is as much as I can offer based on what is known here in the forum. On thing I might add however is if you do have the plates waterjet cut, be sure and undersize the holes for the wheels to be cut by the waterjet and then drill them to the proper size afterward. You'll get a much better fit up.
Thanks for the advice. I am still waiting for the final quote from the waterjet guy. I was thinking more about reducing the overall weight on the Z-Axis. After checking, it seams there would be less than 1.3lbs difference between using 3/16" vs 1/4"aluminum. As far as the holes go that is the advice I received from the waterjet cutter. He'll pierce the center of the holes and I'll drill them later.
My suggestion would be that unless you are supplying the material...maybe you should just buy a set of plates from one of the people here who have actually made them and have great reputations for knowing what they are doing. I can speak from experience and say that you can't go wrong with Chris Laidlaw or Robert Hummel. I have parts from both and their work is very nice. Considering you can be sure what you get will work, the prices are good. I would also like to add that there is a thread here somewhere pointing out that since water jet cuts in a slight V pattern, you might have some post process work to do to bore the wholes and such. Hope this helps.
I am still waiting for the quote. You might be right DiggerJ I just might be better off ordering a set of plates and be done with it.
You won't go wrong working with these guys. There are other members that make things, but I haven't had any dealings with them (yet).
