Thread: Router build
On the gantry ? What's the density ? Wanna see what it's gonna weigh :-)
While i agree about the weight, after all i managed to make 1000x400x200 machine to weight 200kg, something that i don't see on this and many designs are the ribs. Apart from the careful listening to advice and using quality components, the machine in question is build so that there is not a single part of it that is not insured against bend in any directions. By ribs. Hence the precision achieved.
Also there is not a single detail which gives doubt about weakness. Where it looked weak on the initial design, i designed it so that the weak places were reinforced by smooth transition and angles made so to transmit forces in the direction i liked.
Point that look not right to me on your design:
Ok, you will weld 2 beams together for the gantry, i did the same , but where are the side plates that are soldered to them at both sides. They will bend and if not, they will vibrate. They can not be left open.
Gantry legs. i see one plate in the middle that will reinforce them . One is enough against left right bend, but not against twist. i would put 2 on each leg so they form a box.
Web Goblin, your gantry looks very nice. What you intend to do with the gantry legs? Why you did them like that? You plan to fit the screw there? I contemplated this design for compactness, but for my liking it seems weak for left right forces. I would have reinforced this place with closing the beams and drilling holes from above to fit the screws to the bearing blocks.
I did the frame this way because I thought it would give me the best strength while still getting full travel of the gantry rails. The join between the cross rail and foot plate is fully welded and should be very strong.
The bearing blocks are mounted below the "foot" plate. The bmp from my cad drawing below shows how the blocks will be fitted. The top cross bars are not shown here but they will add more strength for left/right forces. The position for the ballscrews is shown as well. These will be covered as well to try to prevent swarf getting to them.
i agree ! end caps are a must ! i intend to have a few internal webs to prevent twist
im not convinced on this one ... if there was only one arm, then yes for sure , but the other arm of the gantry prevents the twist
i think for now im going to go with filling the frame with sand ... but the gantry , im going to try out a epoxy fill
sand with a 1500kgm3 will add 60kgs to the gantry :S
an idea ....
Looking at your pictures of design the box section looks like approx 120 x 80 and not much more than 1mtr long (and your proportions are wrong 120x80 won't have square internal rad they will be approx 5mm.)
So according to solid Works, I've just took the volume of the internal of 120 x 80 x 5 x 1mtr length rectangle section and working on 1470kgM3 which is the closest material I could find in Density which happens to be Melamine resin. The density comes out at 11.29kg per 1mtr length. That's just the internal volume not the Steel.
The same volume with Unfilled Epoxy comes out at 8.45Kg but that's without any filling which you would need. SO I reckon Epoxy/sand or gravel mix would end up weighing much more.!
Last edited by JAZZCNC; 22-08-2014 at 10:32 AM.
150x100x4 1600mm wide
if you go to the bottom of the materials list, you can specify your own material so you dont need to look for a similar material with the density you require ...
the epoxy is only 10mm thick ... working as a sandwich between the two layers of steel
To me your focusing on the wrong areas of the build and not looking at the Basic design and foundation. Without good foundations best resonance handling material in the world don't mean diddly squat.!!
Another thing to ask your self is do you really need massive strength.? Silyavski (Boyan) machine is a credit to him but IMO it's massive OTT for anything but aluminium. SO Unless your mostly cutting aluminium do you really need to go that far.? . . . . Like every thing in life Strength comes at a cost in both monetry and performance terms so why waste both if your only using 100% of it 2% of the time.?
All round machines are great but they take much more to build so they do it well and even then they NEVER do it has good as a Machine specificly designed and optimised for that sole purpose.
Remember a good design is built just strong enough to perform it's role with enough safety margin to ensure reliabilty and anything more is waste.!
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