kiwiken, I sent you a PM so not to clog this thread.

cnc for woodworking
 

Hi,Iwould start building a cnc router for Wood working, please could i have an approximatif cost for it
thank you

Builds in North America have been anywhere between $5000 US and $15000. Depending on your skillset and what you already have around for parts.

Board Size Vs Main Beam
 

Hi All

Wanna try this but no experience with plans and even welding....what I want to know if I make my main longitudnal beam 3350 long, what board size will I be able to work with?

Am i right by saying it will be 3350 - 600mm = 2750 length board?

Sounds about right to me.

Hi to everyone and thanks for your useful inputs.
I was wondering why MM seems so heavy? Yes, according to steel dimension used for the table and the gantry that seems too much. May be this issue has already been raised and answered but generally speaking a light machine should have better performance (and cheaper), but again may be I am missing something. Any input or link is welcome.

Abe

The fully professional CNC routers are much, much heavier. I think you are missing something . . . . .

Some of us have built certain parts more heavy, some lighter, depends on what feel you require. Some areas of the build can be more critical than other areas and have a greater effect on overall performance, example, I built my gantry with a slightly thicker wall tube because my length was longer, I was able to tap directly into the tube without having to use the fastener strip inside the tube. The idea was to help eliminate a bit of flex and the additional work of an extra set of holes to align. Sometimes material availability and the type of use for the router helps make those decisions. The plans are a very good guide and culmination of ideas and improvements others have shared. Most reasoning for any deviation of the plans has most certainly been argued and there is always room for improvements. If you have ideas, share them, ultimately that's why you chose to build a MechMate.

Abe,

GrealdD is right, many commercial comparable CNCs are much heavier.

Some of the comparative and lighter CNCs use hold-down technology rather than gravity to keep the gantry on the table when pushing down against the material/table.

One of the great things about MM is you can build what you want. If MM is to heavy for you, build it lighter. Depending on your size it may be faster or more susceptible to bending issues.

Let us know what you decide, we are interested. ... Jack

It is all a compromise between:
- speed / acceleration (you might be looking only at these and calling it performance)
- flex /chatter / repeatable positioning under varying loads (a massive part of real performance)
- costs
- transportability (especially for companies selling and shipping low-cost machines)

Even the heaviest MechMate shakes like mad when cutting letters on a sign at production speed . . . . . .

Thank you guys for all these enlightening inputs.
I especially appreciate Gerald last sentence "Even the heaviest MechMate shakes like mad when cutting letters on a sign at production speed . . . " which tells lot about MM experience.
However, I still believe that a lighter MM for smaller passes, moderate speeds, etc. can be considered so the over all weight of the machine may be reduced by 20, 30 and even 50%, depending on everyone's purpose. This can be done using MM structural shapes sizes indicated in the drawings with smaller dimensions (example: use channel CH 120x12 instead of CH 180x21 for the table). Mechmate architecture however is undoubtedly very nice and should be the reference.

Personally, I find there's little substitute for mass.

I agree on the value of mass. Big Iron isn't made that way just to sell it by the pound.

<chuckle> I built a smaller, aluminum extrusion based router before I built my MechMate. After you get past the thrill of seeing it work, you move quickly to impatience with those extra passes, and frustration when vibration messes with your cut quality or snaps a mill.

Sure, you can lighten various pieces, but you won't save all that much on the overall cost, and you'll pay for it over and over later. From a performance standpoint, more mass is better. Now,if you're intending to cut cardboard and foam, then by all means, go for a lighter machine.

I haven't commented in a while, but while trying different "mass of gantry" set ups in my initial build of #5, I found that the heavier of the 2 gantries improved my cut quality significantly. Especially when I was doing high resolution cutting of acrylic and aluminum sheet.

Hi Sean,
When you mention the mass of number 5, are you saying you went heavier than weight of the "standard, per plans" build?
If so, could one add ballast to the gantry? Just got me thinking?
Good to see you are still hanging around
Mark

Mark, the heavier the gantry the more it resists the upward forces that naturally occur while cutting. This helps remove the resonance that is transmitted into the lighter materials however there is a downside to a heavy gantry. You soon exceed the workable range of a stepper and now have to move to a servo. So while the cost increases, your cut quality improves as well. With proper planning and implementation that is.

You want the mass. You think you may be making a good choice saving a few buck on a lighter frame by using thinner steel. But in the long run, you will be glad you have a heavier machine. If you want mobility, build a bolt together frame. But I found moving a MM is actually pretty easy even on a fully welded base.

This is not meant for any controversy, but just exploring a new idea according to everyone's needs. A lighter machine may have some advantages like: economy (cheaper steel and electronics), better portability and easier construction. On the other hand, a lighter machine may not be able to handle heavy duty jobs and that applies, not only to Mechmate, but to any CNC machine. Can we think of a "Mechmate light version"?

If you want less weight. ...use titanium. ;)

Joking aside, you do need the weight to help compensate for the forces generated by cutting fast. Unless you gusset and mount solid to concrete footing.

AB, design it. Build it. Do whatever YOU want to do with it. We've given you our opinion of it.

Gerald,

Can you please take a look at this? Parts of the same color are welded, the rest is bolt assembled. Any advice?
http://www.mechmate.com/forums/attac...1&d=1438804233

I dont wish to appear rude, but thats going to rock more than Elvis, needs lots more bracing!

I'm in agreement with Alan.
I doubt you'll get a lot of interest from Gerald in designing a lighter machine.

I don't know about rocking, that normally applies to when something is solid and is moving up off the surface at different contact points. I would say you would have a sway problem. You need sway bracing across the Y and the sway bracing in the X also functions for upward support of the longitudinal beams. Steel will sag and more than you think even with a little weight. I have walked across 50 ton bridge cranes with 3 foot I beams when I inspected hoist and cranes, just walking and the steel will react (no I am not that big either). You can build lighter but with lighter the complex angles of the bracing that will be required are normally outside the capabilities of the average person.

I will say I prefer the concept of Gerald's design and it can be built upon. I will not knock you for trying something different because if nobody ever did, nothing new would be conceived. If you are to proceed with this I would make some changes as the sway braying and sag prevention is not provided yet in this concept. Welding the saddle to the horses you have would be good idea also. In the end, I think the stuff needed will weigh more than the original design. Just my opinion.

AB, I am not going to get sucked into a discussion like this.

Cable brace it. After a little careful tuning, you'll have the first symphonic MechMate.

(Not a serious suggestion)

I think I still have an offer open for a MechMate singing a recognisable tune :D
The one pictured above will be good for low bass notes :rolleyes:

You guys crack me up.

Thanks Pete for your input.
I realize that more weight for a sturdy machine cannot be avoided. I tried however to make simple and bolting parts instead of welding is much more easier to handle smaller parts and also adds more precision. The table may be easily dismantled and moved to a different place (keeping upper part and rails adjusted) so all is needed in re assembly is table leveling by acting on threaded rod of the shoe plate. Overall weight is about 325 kg.

Thanks Brad for your symphonic compliment.

Thanks to all objectives inputs. Sorry for those who are upset.

Attached is a higher resolution image.

[IMG]http://imagizer.imageshack.us/v2/xq90/537/U7NlcI.jpg[/IMG]

I did a bolt together design based off of Gerald 's design. All crossbearers bolted to main beams, main beams bolted to side legs and cross supports bolted to the side supports. All with sway bracing. If I need to tear apart, I have 1 gantry, 2 sides, 2 cross supports and 9 crossbearers.

I don't think anyones upset, AB.
I wish you luck and success.

Yep, nobody's upset. I also have a bolt together machine; beams, legs and X axis bracing welded into two long "side" units, Y axis bracing and the first cross bearer welded together into two short "end" units. The four units bolt together, and then the remaining cross bearers ( with the table surface ) bolt onto the main beams.

Thought I'd chime in at this point. After earlier conversation about the weight I did a quick rough calculation of mine and weigh in at roughly ~2100 lbs + the weight of 10-12 sheets of plywood stored on the shelf below. I originally wanted a bolt together unit but changed my mind for a fixed base and glad I did. It is rock solid (thank to Gerald's design;) and Darren's overkill build influence:p) with absolutely no worries about movement even running at 700 ipm (setup has got to be right though:eek:). Brad has it right though, if you are going with bolt-together that's probably the best way.

The extra is for trimming flush to the board edge. If they were the same size, most would not be able to match the edges up perfectly in a contact cement application.