Fully supported linear bearings - Radial squareness

[Slixxor]

Thanks for the feedback. Yes I do need to support it more. I will add some gussets and some 45° angle beams to support the top rails and some on the lower section as well. Steel used is 65x65x3mm box.

[Ger21]

I am building a new machine and have done my research here and on other forums to build a good sturdy design for milling timber, ali and steel.

I am using SBR20 fully supported rails

I wouldn't consider SBR20's to be anywhere near rigid enough for milling steel.

[Slixxor]

One step at a time. :)

This is my first machine so I will take my time with it. I'm happy for a job to take 5 hours to complete if it has to. The only time I will be milling steel is for small components. I will build it first, try my usual maple ply and then some 5060/6065 ali. If it goes well I will chance mild steel with some carbide bits. but it isn't critical.

I am not a machinist by trade, my profession is custom software and electronic design. I have worked on some GRBL controllers in the past. I decided to do this project to have a worthwhile machine in the lab and learn something on the way. I am writing my software front end (similar to Mach 3 but much nicer) that will work specifically with my machine bed size with a heavily modified version of Arduino GRBL that is running at 200kh on an STM32 ARM cortex board.

From looking around the forum I see a lot of skill gaps. Most users seem extremely proficient on machine design and structrual engineering but lack the electronics skills. I am quite the contrary. Finding myself reading google e-books on structural integrity and CNC/crane gantry designs.

I am more than happy to invest my skills in helping people out and love getting some good advice in return. I will weld up these gussets and some supports tonight.

[mekanik]

Hi Slixxor
If you have your design in some kind of software post it, and the guys with more experience than myself will offer advice, really need to see the gantry arrangement.
Regards
Mike

[Paul3112]

Hi Slixxor,

I am in Melb Aus. If I can assist you in any way.

You might not of seen this thread http://www.mycncuk.com/threads/4356-...upported-rails
The square tube will rhomboid with side load ( assuming gantry uprights are the top of the frame )
Three trucks are better than two trucks ( better load spread )
Regarding tool load what spindle are you using ..kW RPM etc ,, have you seen "CNC Cookbook"

Finally, Hey Ger, Very nice to see you here.

Paul

[Slixxor]

Hi Paul. Yes I have seen the page. I am planning on using a 2.2kw water cooled spindle. Z axis range of 300mm. My rails for Z are 450mm long. I am adding 45° gusset/supports to both sides of each corner of the frame. I will be running dual ball screws on the X axis to minimize racking each with their own nema34 34HS59-5004S. Still havent decided if I'll be using the same size stepper on Z just yet or slightly smaller.

I haven't done a cad example of my design for reference. May do shortly pending work commitments.

[Neale]

Sure that those Nema 34s are a good fit for this size machine? Nema 23 would be more usual and this is a situation where over-building is definitely a bad thing. I was talking to someone last night who bought someone else's project router and with Nema 34 ("bigger must be better") he was getting no more than 1m/min when with the correct motors he should have been seeing 5m/min or more. Big motors come with much more inertia and high inductance which are both speed killers. Might be worth a bit of investigation?

[Slixxor]

The bed size is 1300x1000. I am happy to run whatever I need in order to be able to mill aluminium comfortably. I opted for the 34's due their torque at low rpm. Can anyone suggest a nema23 suitable for the application, they certainly are cheaper :)

[Clive S]

The bed size is 1300x1000. I am happy to run whatever I need in order to be able to mill aluminium comfortably. I opted for the 34's due their torque at low rpm. Can anyone suggest a nema23 suitable for the application, they certainly are cheaper :)

nema 34 is overkill and won't work as expected try these https://www.cnc4you.co.uk/Stepper-Mo...YGH301B-Nema23 more than capable for that size of machine

[lucan07]

My 1000x700 build uses Mema 23 425oz 3amp at around £20 each, and they plenty of torque and speed, forgot to change DOC other day set to 3mm 6mm 2 flute for MDF (cuts MDF 6mm 2 flute at 15mm DOC Regularly), so ended up slot cutting 5083 aluminium at 3mm DOC 6mm 2 flute 1000mmpm FR, stepper torque was not a problem and it cut without incident but was working harder than it would normally.