a Steel Box Section Build with SBR20 & Ballscrews Plus a few questions

[grain_r]

I have though Mounting of the rail mounts on a 10mm Steel plate that is tig welded to the box section (Maybe Bolted for a little movement) ? and this way I can have the actual frame as wide as I like but just the cutting will then still be the same but this way I could put larger material on the frame and move it around if I ever wanted to e.g for cabinet doors at the moment I thing I would struggle to fit it on. and yes it is all because I bought before I thought ( I might use that saying again I like it)

I am still unsure if putting the gantry SBR20 rails would be the strongest design for the top and bottom or both on the front, or maybe have the one rail at the top and then the lower rails on the front.

I am really sorry I haven't used the X,Y,Z because I think I get it wrong when I say it, I thing Y is the movement of the whole gantry and the X is the movement of the across axis e.g. moving of the spindle left and right and I know I get the z Right 1 out of 3

If someone could confirm this or tell me I'm and idiot and have it wrong that would be much appreciated.




I have chosen the have a sliding Bolt through for the bed in the middle with a bracket tig'd on the box section and then I can bolt through to give extra strength but then at the ends just go through the actual box section of the base although I'm not sure if this will take away a lot of strength from the base.
also I though I would be best to mount the screw blocks on the outside of the gantry to stop dirt getting into the screw. there will be screws on each side to stop any problems however I am currently leaning to using 2 motors and not a timing belt but you might tell me differently.





Any comments would be very much appreciated

thanks for looking through and listening to my ramblings



Rob Grain

[EddyCurrent]

Take a look at this diagram, you can see that in your design the spindle would hang out from the gantry well past the bearing blocks.

http://www.cncroutersource.com/do-it...NC-router.html

It's usually regarded as X being the rails mounted on the frame, Y being the rails mounted on the gantry, Z where the spindle mounts.
Two motors on X works fine, just remember you would then need to, rate your power supply accordingly, purchase another stepper driver, add 2 home switches. It's generally regarded as advantagous to connect the motor to the ball screws using timing belts, the pulley sizes can also be selected to increase or decrease speed so that your stepper motor is working in it's optimum range while the cutting speeds are also optimum.
You might need this as you indicate 1605 screws all round, I'm using 1610 on X and Y which seems right using 1:1 ratio of pulley

[Clive S]

Rob Welcome to the forum. Please don't buy anymore kit until you have your design finished its the biggest mistake people make. Ask as many questions as you can (a few at a time is better) and expect a bit of leg pulling but you will get all the advise you need on here.
There are generally two ways to drive the x screws either with one motor and a belt going to the other screw or using two motors one for each screw, there are for's and against both system. But they both function ok.
You will need more bracing of the frame that what you have. ..Clive

[grain_r]

Thanks guys for that, I have put the spindle so that it will go past the frame so that I can cut on the end of material for letting on the sides of work, Although I suppose I am stopping me from being able to cut sheet as long as I would otherwise be able too. I have thought about moving the rails back a little and then making a clamp so that I could lamp it to the internal 'Y' support beam.

I thought I might be under building on the supports. Because I am going through the centre vertical beam I will have to have a change to get the support in. would it be best to brace from corner to corner or is it as strong if I triangle off the corners

I seem to buy the stuff and then learn and I have after many years started to come out of that routine things always work out but always a more difficult path and more stuff for the spares box.

[grain_r]

Hello I have been doing a spot of re-design for the bracing Hopefully I haven't gone the other way with it now. I was trying to use a little less steel to keep the cost down but I would certainly rather have a stronger machine.