3 Axis CNC router

[JoeHarris]

Ha ha looks like my build log got high-jacked only a couple of days in!! Looks amazing though. Thanks for the further info Jazz and hope your eyes are ok. I will try to get images of progress up in a few days...

[JAZZCNC]

Ha ha looks like my build log got high-jacked only a couple of days in!!

Ye full of pirates and bandit's this place John S being Captain black beard . . " Argh argh yeh bastards who's swipped mi Hobnobs.!!"

Anyway don't complain too much because when you do have it cutting and wanting something to impress the Mrs you wont have to try remembering which post ya saw that Aztec calendar. . .Lol

[JoeHarris]

Anyway don't complain too much because when you do have it cutting and wanting something to impress the Mrs you wont have to try remembering which post ya saw that Aztec calendar. . .Lol

Oh I'm not complaining, just a tad jealous - need to be patient!

[JoeHarris]

OK!

Finally got round to making some progress on the model of my machine. I have made a load of changes / developments based on your very helpful comments so far. I have uploaded some screen shots and an honest appraisal would be very much appreciated, together with any ways you can think of to make it cheaper!!

Thanks again to all who take a look at this.

Joe

p.s.for anyone who is interested this thread started at http://www.mycncuk.com/forums/showthread.php/4489-Hello

[Jonathan]

Currently the number of teeth on the X-axis motor pulley engaged with the belt is too small - it will slip. You should put an idler either side of the motor pulley to force the belt to wrap around it.

The travel on the Y-axis is limited by when the Z-axis makes contact with the X bearing block support, so there is a gap between the position of the Y bearing blocks at this limit and the gantry sides. Therefore you could space the Y-bearing blocks out further (with longer rails to match) to add strength without compromising travel.

The piece of aluminium extrusion underneath the gantry that links the two sides doesn't really add any strength since the gantry is well supported there by the ballnuts. I would get rid of that extrusion and clearly shorten the gantry sides where it was. The Z-motor mount can also be made narrower near the motor to save material.

[JAZZCNC]

I see the same things Jonathan does but I also see other few factors that you may want to consider.? Some regards build design, some practicle usage considerations.

#1 The distance from the lower bed to spindle appears to be approx 100mm.? You also have drawn a sub base which would guess being 19mm MDF spoil board.? That leaves 81mm total distance for material and tooling. Basicly giving a Max tooling length and material thru cut of capabilty of 40mm which hisn't much.! . Most drill flutes alone can be longer than 40mm, even a short endmill will stickout from spindle 20-30mm so unless you only plan on cutting thin material I would look to increase in height in this department.

#2 Consider how you will mount the X axis bearings to the plates and still have access to the screws.? The way you have it drawn at the minute the profile will cover the holes unless you install the profile after. Idealy you would want the bearing plate,profile and gantry sides to all be bolted together for Max strength but the way you have it at the minute this wont be possible and way it is will make setting up the machine regards squareness etc a pain.
An easy fix would be to have 2 bearing plates, one which mounts to the bearings the other part of the whole gantry which bolts to the bearing plate.

#3 The bed supports all run length ways.? I would run all inner or at least one central width ways with 2 length ways offset as the shorter length beams will be stronger reducing bed flex and beefing the frame up in all direstions and esp the long length.

#4 Check the linear rails base will fit the profile width, some are wide and the mounting holes may fall in the wrong place were there's no much material in the profile or directly inline with profile internal structure making drilling amd tapping very difficult.?
Often it's better to mount a wider plate to the profile then mount the rails to the plate, it certainly makes drilling and tapping far easier.

Hope these things are usefull.

[JoeHarris]

Thanks both for the advice, I will update and post again!
Are you sure about removing the y axis profile under the bed i thought this would stiffen up the y axis without putting extra strain on the screws? The 100mm dim on the z axis is from the bottom of the z axis mount to the top of 18mm mdf / alu plate bed btw...
Joe