New Machine Build- My Next Build(Much Smaller)

[twistedfuse]

Hello All,

Well im still having great fun on my other CNC machine when i get the chance, but with the end of tax time coming my work is slowing down slightly which gives me more time to build and play. The other eason i havent done much is the darn cold weather. lol. So my next 2builds(yes im thinking and designing 2 as i go) will be much smaller.

For the time being, the machine im building next is for a couple of specific reasons. Firstly im looking for a nice simple cnc machine, small cutting space that will allow me to hopefully bring it inside the house as it will be quieter and self contained. The second reason is i would like to do all my lithos, engravings and small mother of pearl inside this machine as it is a pain sometimes to setup small work on the larger machine. Finally i have been trying to get my other half involved and she thought it would be nice to do simple rings etc, so this machine just seemed to fit the build, so it will hopefully fit a 4h axis within to allow me/and the better half to make rings from wax and cast them. It will also allow me to hoefully use the first cnc to build alot of the parts since the overall footprint of the parts is small (and to keep costs down).

Anyway, Ill post the CAD photos i have of the machine idea so far.
Daniel

[twistedfuse]

Well,

I guess i hould outline a few of the design ideas/ dimensions etc. I also have a few questions i was hoping you guys could help me with. Thats the great thing about this site.

Firstly, the desgn so far is designed to have a cutting space of roughly 150mm x 200mm and a z height of about 70 - 100mm. The entire unit footprint is going to be roughly 400mm wide x 500mm deep x 450mm high. I have a few rails laying around here that i was able to get quite cheaply and they are 25mm rails so i have decided to use the smaller ones from the lot as much as possible for the build. The X Axis should be very straight forward as should the rest but i just have a few problems or things i would like opinions on.

Firstly as this is using 25mm rails, i was curious as to what size motors i should use. I have a second chance option on some nema 17 300mN.m torque motors and was thinking if i could use these it would keep it all compact but not sure if it could move the X and Y axis properly, would te rails be too beefy for the motors? I have no problems going to some Nema 23, just in the spirit of things i'd like to keep it s compact as possible. I am also thinking about using some reduction gears to give better resolution but not sure.

Also my Y axis as you can see, has only 1 25mm rail and i was wondering if that would be enough to support the loads and the z axis from moving. The Ballscrew will be mounted directly above the rails trying to give it some extra support. As for the spidle ive have a couple ideas. I was thinking about using a model plane motor and getting a spindle made/buy a pre-made spindle or mounting a flexi shaft for a dremel. I'd prefere the first as it would be light and have less runout than the flexi shaft im thinking. Also it would be alot quieter.

Anyway, If anyone has any comments it woul be greatly appreciated.
Look forward to having the support/help from the zone as i did with the first build.

Daniel
P.S As for the Z Axis i have no clue how im going to keep it compact except maybe using timing pulleys and belts and have the motor suspended above the ballscrew. Also i am thinking about building it out of wood(Maybe all thread to start as well) to get the main ideas and concepts done first and then upgrade as neccisary.

[twistedfuse]

Thinking now that im better off running with leadscrews and changing them out with ballscrews after i figure out final design and also for space issues. So far most ballscrews have a flange that boarder on the too big for the space. Im in the process of getting a quote on ballscrews of about 12mm diameter with flanged nut and a lead of 2mm. That way i should be looking at about 0.002mm(2mm Lead / (200 Steps x 1/4 Stepping Controller)) for my resolution. Im sure itll end up more like 0.01mm but that would suit me fine, Worst comes to worse, ill end up using timing pulleys and belts with reduction.

Daniel

[twistedfuse]

Well,

I guess its quite on the zone. Missed the motors but am moving on with the build. Will be buying extra parts and orderng some electronics soon too. Getting quotes on some ballscrews which i may look at just getting it all done. Looking forward to starting soon. My only problem is the X axis across the gantry. The rail is a 25mm rail and 12mm ballscrew. Is this substantial for the build. Would i need a second rail?

Daniel