Gantry design?

[Black Forest]

I am building a 3x2.5 meter router. I am curious as to what you all think the merits of either a Mechmate style gantry versus a vertical type gantry would be. The machine will be used mostly with a tangential rotary knife or a drag knife. The ability to use as a router also would be good. It will have either Delta Servos and drives orClearpath servos and use a Centroid Acorn controller.

I am not really trying to build it as inexpensive as possible so that is not a driving force behind most of the decisions.

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[awerby]

I like the Mechmate design better than a tall vertical gantry, because it's more rigid, and doesn't have all that leverage working against you. But if all you're using it for is cutting with a knife, that's not a major concern. It's when you're trying to control the vibration caused by cutting materials like wood and aluminum with rotary tools in router mode that the difference becomes evident.

[he1957]

Agree with awerby, the non-tower gantry design would be easier to build and not have so much flex to deal with for higher loads or faster speeds (velocity profiles).

The general design of the frame used in the FLA (Fine Line Automation) Saturn 2 looks quite similar to the MachMate and overall seems pretty good. With properly machined surfaces to mount profile rails and racks on it would be very good. With no machined surfaces then round rails on inbuilt carriers might be a reasonable compromise as they should provide an easier to align travel surface plane.

I do like the sound (sales pitch) of the ClearPath servo motors - their design and flexibility of use reads as very impressive but others who have already used them might like to chime in and provide some feedback on them. (I'm thinking about them as a new project and also as an upgrade for my stepper based machine in the future).

[davida1234]

My 2x3 bench top build (David A's 2x3 bench top CNC) is using ClearPaths. Pretty smooth and easy to integrate so far but I haven't run them in a "real" environment yet.

[ger21]

The reason the mechmate gantry is designed like that is because it only uses gravity to hold it in place. I believe it's quite a bit wider, and requires a longer machine for the same usable area.

[wizard]

What do you mean by vertical design? Any design can be made rigid. The first thing I thought about when looking at the mechmate design is that it has to suck to change the cutter on that router. So you might want to consider human factors in a machine design you choose. I only mention this because a lot of EOAT (end of arm tooling) on the robots at work are very hard to access and work on, so for that reason alone I would not go the mechmate route in manual tool changes are required. The older I get the less impressed I am by poor human factors.

It doesn't sound like routing is a primary goal here. Even so I still believe that most DIY designs suffer from gantries that are not as stiff as they should be for what the user expects out of the machine. Given that I usually suggest a large square steel beam for the gantry as easy and well proven. In any event reading the stickies is a good place to cover a lot of design consideration in a short period.

[Black Forest]

What I was looking for was the various pro's and con's of the different gantry types. I think you all answered that for me. Even if I built a MechMate style meaning side by side rails I would for sure not have it only held down by gravity. And I definitely think easily changed tools should be a consideration so I would build the table so the gantry could run off the end of the table to give clear access to the cutter or spindle.

Thank you for your thoughts.

[wizard]

And I definitely think easily changed tools should be a consideration so I would build the table so the gantry could run off the end of the table to give clear access to the cutter or spindle.

Thank you for your thoughts.

Running the router off the end to give good clearance for tool changes would certainly work. Just realize it results in a bigger machine foot print.

[Black Forest]

Running the router off the end to give good clearance for tool changes would certainly work. Just realize it results in a bigger machine foot print.

Do you really think that anyone would not know that the machine would need more space? Really, talk about stating the obvious! Just so you know, I am not blond!

[WilliamT4450]

Sorry to be late entry; I just saw this post today.... All good information here. Please allow me to add.

I built a MechMate a few years ago and it has served me well. It has a cutting envelope of 6ft X 12ft with an 8" Z, or ~1.82m X 3.66m with 20cm-Z. It is used primarily to cut 6061-T6 and 2024-T3 aluminum. I am using Clearpath Servo motors as drivers with 4.5:1 reduction. The servos are NEMA 23. Yes, that's right. NEMA 23 Clearpath servos and they can easily propel the 60 kilo gantry beyond 500ipm. The servos are nothing special, the least expensive they offer. I am using a Hicon Integra 7766 controller. It is a very robust controller but you can find excellent controllers today for a lot less money than the Hicon.

Be careful when up-sizing the gantry of any design, MechMate included. The longer you make the gantry the more flex you'll find in it.

I'll be happy to share more information if you need it.

BillT