Thread: CNC Build - CH1

Hi Glenn,
These are opinions so take it as such.

Reduce the 10/12mm plates to 5mm but make sure you have at least 150 by 5 plate for the sides. By using 5mm your cross braces have a chance of straightening the steel. Steel is never straight so if you use 12mm plate what will happen is the machine will follow the curve of that plate.

You cross brace angles increase to 50 by 50 by 5 or 6mm that way you have enough material to tap into.

Move your angle brackets inside the angle - it means you will have to radius one edge to match the internal radius of the angle (I do this on a sander) but it will then be sitting under the cross brace therefore providing more support.

Can you get you X axis rails higher in the design? I put a piece of angle at the top of the plate flip the rails through 90 degrees compared to your design. The higher you can get the rails the more rigid is the gantry. It does take up more room in the design so this might not suit your space restrictions.
Think about a beam rather than plate for the Y axis. The Item, etc T slot stuff is great and I would not go back to plate again for a gantry. Also why not poke the ballscrew end through the gantry side then bring the belts to the back of the gantry rather than breach the gantry plate with a slot.

Just some options to think about.

Hi Rod,

Thanks for that

I actually didn't realise that about the steel, i thought being on the thicker side it would had a higher chance of being straighter.

Also good point on the thickness of the angle, I was thinking of just using bolts and nuts but tapping would be much better.

I'll should be able to raise the rails by another 50 or 60mm, originally i was thinking of using the method you do but started to run into size issues

I was also a bit worried about running the belt through the gantry plate, . Poking the ball screw and stepper through the gantry won't really add that much to the size (20-30mm) so it does make sense rather then mucking around.

I'll make some changes on the design and see how it comes out

Thanks again for the guidance
Cheers
Glenn

hi all Happy New Year
Thought it was about time to post an update before the thread disappears..

After finalising the design I have been slowly collecting all the parts etc.
Few changes as per Rods suggestion, i went with the extrusion for the gantry and also for the bed. i can see why everyone uses it, its fantastic stuff!

I bought it through Wesley at Modular Components in Melbourne, great guy really helpful and guided me in choosing the right product for the job. He also tapped the ends!... yes lazy on my part i know

So far i have managed to get:

60 x 60 Extrusion for the gantry and bed
Hwin 15mm rails and bearing guides
1400mm RM2005 C7 ballscrew
660mm RM1605 C7 ballscrew
300mm RM1605 C7 ballscrew
3 x 570oz steppers
3 x 203V Geckos
Power-supply
Associated bolts and screws.

I got the bolts from boltsnutsscrewsonline.com (highly recommended), only a relatively new business. Jimmy the owner was extremely helpful and pointed me in the right direction on a few things and was only to happy to help, good prices and fast turn around. also got my taps from him as well.

hoping to get started on the ally parts shortly, will post more when i do.
cheers
Glenn

Looking good Glenn.... Post lots of pics!!! as it's coming together.

Brad.

Managed to make some more progress this weekend..

Received the sides from the laser cutters, they did a great job on it, accuracy is pretty darn good, was a little worried about the smaller holes but they came out fine.

Tapped the rail holes, did the countersinking (after some fiddling around with the right depth) primed and sprayed (hammertone is great stuff! decide to go with charcoal).

Next fitted the ally extrusion to the side plate, loaded up the t slot nuts and fitted the front and back plate, then attached the other side.

Seems to have gone together relatively well and 'seems' to be fairly square, will need to do some checks on it though to make sure its ok, will need to do some reading up on this.


Does anyone have any tricks for fitting the bearings to the ball screws?
I had my ballscrews done via Chai, the bearings seem really tight and i'm struggling to get them on!

Not sure whether i may need to take them to a machinist and get them adjusted, although obviously prefer not to as it is pretty $$.

I'm starting to see how addictive it is making these things...WAY TOO MUCH FUN!!!

Cheers
Glenn

Yeah my bearings from Chai were also very tight. I just rolled the ballscrew on a table with a file on the machined part to take off a little. It took a while, but wasnt difficult.

Brad.

Wow the laser cut and the charcoal hammertone both look amazing.
I put my bearings in the oven on 200c and they pretty much dropped on. I had some tube about the size of the inner race ready to give them a tap.

Cheers
Brian

Thanks Brad, I'll give that a shot tonight I think that will be the best solution.

Brian, will putting it in the oven affect the seals at all or dry-up/release the grease within the beaing?

A combination to the two should ensure a nice tight fit.

thanks again
Glenn

Hi Glenn, Probably not a good idea to go too hot with the rubber seals. I am no expert on bearings I am just saying what i did to fit them. Trouble with a small bearing is they cool down pretty quick and don't give you much time to put them on. I also had to wait until the wife was out of the house before warming them in the oven and having the ballscrews and blocks of wood etc all over the kitchen floor.

BTW I still have laser cut envy.
Cheers
Brian

Glenn,

That is just awesome mate!

I love the construction and the laser cutting has really made a difference - well done. It also looks like it will be very ridgid.

cheers, Jason

very clean and professional job. will be watching this build with interest.

row

Thanks for the comments guys!

Jason - I wish I had listened to you sooner and had a go at making it!

Does anyone have any experience in loosening up the fixed end bearing supports when locked onto the ball screw?

I remember reading in one of Rods posts that he used shims between the bearings to remove any play which seemed to help free them up as well. I tried the same and stripped the bearing mount down and made some 'washers' from some thin aluminium, added up to around .5 to .75mm.
But they still seem too tight when you try to turn them, it feels as though its actually the rubber which is locking it up??

Thanks
Glenn

Hi Glenn,
The rubber seals sometimes need to be pushed in further. I used a piece of rod turned to size and tapped them down. Perhaps a piece of wooden dowel would work as well.
If you look at the nut make sure the side with the raised rim faces the seal.

The shims are to take out the end float on the bearings. You know when you need them because if you tighten up the nut you can feel end float on the ballscrew. The bearings are pinched together so do not overthighten the nut to cause too much drag on the bearings - this will make it difficult to turn as well.

Lots of rambling but if you understand how they work you can adjust them with only a bit of drag on the seal and no end float on the screw.

Thanks Rod appreciate it!

No ramblings at all, very relative and makes perfect sense!
Will give it a go morning. Hope to have the ballscrew installed on the bed tomorrow ready to make a start on the gantry.

Thanks again
Glenn