Let The Fun Begain, New build on the Table.

[Bush Flyer]

Ok my mistake it is 2.85Kg and not 3.4Kg I made the mistake when I converted from 6.283Lbs to Kg.
Right now we know I'm an idiot I have changed the design round to the rails on the same plate as the spindle, The reason I did it the other way round was there would be less weight for the stepper motor to lift, I also have a question about the gearing, If I used a 2:1 will I not lose torque but gain the speed from the stepper motor?
Here is my new drawing see what you think, I would have liked to put the two bearing blocks in line with the gantry blocks but i would lose a lot of travel, Anyway how high should I make the bottom of the Z mounting that holds the router from the table.

[Ross77]

Hi,
As Jonathan said this is all covered in most of the previous builds. Revised plan is much better but you could gain a bit more rigidity by moving the lower block down to match the end of the rail as your z axis blocks look a little close. The z axis is the weakest part as it is a cantilever and will flex the most, A larger distance between the blocks will also reduce the bending moment on the y axis (rotational lever arm effect) What travel where you looking for?

The z axis blocks don't have to be in line with the gantry blocks and it might be worth centralising them on the plate so the bottom of the router plate is in line with the bottom y axis beam as that will mean you can lower the gantry sides (whilst retaining the same clearance)to reduce the force on the x axis bearings.

My comments are only to help maximise the performance of the parts you have and are not a critisim of your design. Happy building

Edit. whilst supported rail is stronger with regard to the rail, the bearing is weakened by not completely wrapping around the bar therefore the bearings have reduced strength when pulled away from the rail , this is easily solved by mounting the rails back to back, or in your application on top and bottom rather than on the side. For example in your sketch when the gantry moves to the left the z axis (due to cutting force) will rotate about he lower bearing on the y axis and try to push the top bearing (strongest direction) how ever when the gantry moves right it will still rotate about the lower bearing but now will be pulling on the bearing which is the weakest direction.

Again this point is just a way of maximising the machine strength by design and I'm not saying that the method you have proposed is not good enough as it is probably more then adequate for most uses but my option just increases strength for free....

Height of the gantry needs to be as lower as possible but allow for the max depth of you work + how deep you need to to cut. for example if you work piece is 50mm and you want to cut all the way through you need to allow at least another 50mm for the cutter + shank and collet so say 125mm.

[Bush Flyer]

Hi Ross77
Right here I am again with the Mk10 drawing of the Z axis, I may see one or two other ways of doing this but I thought I would let you see where I am at this point.
I have about roughly 120mm of travel in the Z axis.
Now about the height from the bottom of the router mounting to the table top. Do you mean that would be 125mm?

[Ross77]

Yep that looks good. Mk10? so you have only just started then

I would increase the distance between the y axis rails to match the z axis plate to increase bending and torsional resistance.

If you have mounting clashes with the blocks then widen the plate, it would be best to make any compromises on the y axis side of things as this is more forgiving than the Z axis.

Yes I did mean 125mm from the bed to the router base. Is that not what you were asking?

[Bush Flyer]

Thanks Ross77 yes that is what I needed to know, I was just double checking Before making any more adjustment. I appreciate your help.

[Ross77]

Just thought I'd better check but the 125mm was only an example, actual value will depend of your router collet and cutter length.

What router/spindle are you using? can it be fixed at the top as well? as the L shaped mount is also a bit weak.

[Bush Flyer]

I have now reinforced the L shaped mount. Its now braced right to the top now.
The router that I will be using is the Kress 530 with a 3.175mm and a 6.35mm collets and I was going to get the mount from CNC4YOU.
Here is the latest drawing of the Z axis.