MTC 4'X8' gantry idea?? Well I’m still wading around in the muddy waters of my 4X8 MTC. I have done a million versions of the gantry. I have to work with extrusion I have already cut. I kind of like this idea and want some feed back. I’m thinking of using the whole bridge deck as a Z axis, using a rack on both uprights. One nice side affect is it gives me some room for the 4th an 5th axis. Below is the concept in rough form.
duluthboat - spent that winter season thinking - eh?!
Cool concept. I can speak to the y axis - the "straddled" router to rails is very secure.
I like the vertically moving bridgedeck - expect will take a bit of working through the masses involved though. Might pay to use a moving table for the x axis and then you can realy beef up the mechanism to move the bridgedeck/gantry up and down.
Like the concept - look forward to others thoughts.
Cheers - Jim
Experience is the BEST Teacher. Is that why it usually arrives in a shower of sparks, flash of light, loud bang, a cloud of smoke, AND -- a BILL to pay? You usually get it -- just after you need it.
The amount of bending is proportional to the 3rd of 4th power of the length in the perpendicular direction of the force being applied (i.e. the "beam" length). For x and z axes, this is the width of the gantry and since this is dictated by table size, it's not something that can be modified. The bending is also proportional to the thickness in the axis of the force being applied.
The key to stability in the gantry, then, is the "effective" material thickness in the same axis as the forces being applied. So for let's say an upward force (z direction), increase the size/bracing of the gantry height. The mod looks stable but it may be prone to bending forces when a lot of force is applied in any of the given directions. It's usually more economical to build a well braced gantry system that effectively maximizes the "thickness" in each of the axis directions, then to build the gantry out of solid or closely spaced material.
BTW, nice rendering. Are you using a 3D mechanical package like Solidworks?
Last edited by bsmith; 06-05-2004 at 08:49 AM.
Jim,
Yah, progress has been almost zero, I should just do it.
bsmith,
I agree with you, I’m, reworking a design for which I have already cut the stock. I’m not sure if I’m moving forward or backward. The software is Rhino 3.0
Gary
Gary,
I like your ideas but I fear for the stresses when under changing directions so I added these trite symbolic "gussets" to the sides....I know you give up space, but I think it will need some sort of bracing such as this...
Bloy
Last edited by Bloy2004; 06-11-2004 at 12:11 PM.
I cleaned it up a little and I still like it. The uprights are so short that I doubt there will be much flex; most of the stress will be on the joint below. This should be at least as strong as the original plans.
Gary
I like the design. I assume both sides are rack driven. I would think this design is conducive to flexible cutting volumes because it keeps the router close to the work. With a more conventional design you compromise rigidity when you have a long z axis. With your design rigidity increases with thinner stock.
What if....you hinged one side of the crossmember and slotted the other side and drove each side independently (similar to a cnc wire foam cutter). You would have a strange limited fourth axis.
Ok Gary,..........what is a MTC?
Mike
ps I'm slowly but surely learning my Rhino! I love that program!
No greater love can a man have than this, that he give his life for a friend.
MTC = Machine Tool Camp, I have had their 4 X 8 engineering package for a long time. Connstruction was almost complete when I decided to change a few things. Then I found the Zone and all h#ll broke out. I think this is the last rework.
Rhino has become my tool of choice for design and modeling.
Gary
Here is a little more expanding on the z axis bridge. It has accrued to me that this is only a good way to go if you are cutting sheet stock. With the whole bridge down close to the work you can’t have anything sticking up.
Gary
Yes and no....you can mount your router so it hangs below 3 ". What is wrong with a more conventional z axis approach? Not that I mind seeing peoples innovative ideas.
Eric
I wish it wouldn't crash.
“What is wrong with a more conventional z axis approach?”
LOL!! If there was anything wrong with it, it wouldn’t be conventional. It is my curse to never be satisfied with the conventional. I try to read and learn from other peoples mistakes but in the end I’m destined to continually put my hand in the flame before a lesson takes hold. Now with Rhino and the Zone I can share my wanderings with others in a hope they will not climb a tree that bares no fruit. The worst is when I get little response from my ideas, I don’t know if this means there are no good arguments against or if it is so crazy that it isn’t worth a comment.I value all response and still have much to learn.
Eric, thank you for taking the time to respond.
Gary
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