First CNC Idea Sketchup - What Do U Think?

[Telly]

So ive been looking around the forum and working out what i can do between a home and work build. Ive come up with a design using Sketchup and was wondering what the community had to say about my design.

I went for a design that uses 18mm MDF and 12mm linear bearings.

So onto the design!









As you can see it is a large design, i wanted to make it big so i could hopefully produce smaller "upgraded" CNC machines on it.

I was just wondering if it would have a bit too much "slop" on the X & Z movement?

This is just Version 1 at the moment and can be adjusted or changed.

Any more info needed just give me a shout.

Thanks for looking,

Matthew.

[ger21]

Originally Posted by Telly I was just wondering if it would have a bit too much "slop" on the X & Z movement?

Yes. Unsupported rails will have too much flex in them.

[LeeWay]

I concur with Ger.
The unsupported rails will instill unneeded grief for you down the road.
If cost is an issue, using just angle iron and skate bearings would be a much more rigid option for about the same cost. Plenty of those type designs around to check out.

[Telly]

OK then! Ill do a redesign and get back to you.

Thanks for the help!

Matthew.

[ahren]

Matthew,
Lots of folks have had success with supported rails from VXB, and with other solutions like skate bearings and V-bearings. Interested to see what you come up with for your redesign.

Best regards,

Ahren
www.cncrouterparts.com

[Telly]

Wow this was hard to draw on sketchup as the is the only designs I made on it so far, so Ive made a small bit before going crazy.

I have gone for the type of clamp used on roller coasters, a "G" type clamp surround a 18mm x 18mm solid square bar.

Take a look at the pics.





The drawing sketch is not perfect yet, I just wanted to find out what u thought about it. I'm too tired to continue now after trying to fix a machine at work for about 7 hours.


Thanks,

Matthew

[Telly]

So the design before was a bit "steep" so i'm back with a tried and tested method.



BTW the bearings are running on a aluminum angle.

Ill start building soon!

[LeeWay]

At that point, I think aluminum angle is the wrong choice. Not much difference in cost for that size angle between aluminum and steel. Steel, even hot rolled angle, would be a better choice than aluminum.

[Telly]

What is the difference? The longevity? I have some alu angle already, but i can always have another hunt around my dads machine shop.

Thanks.

[LeeWay]

Both will wear a bit at first, but aluminum will keep wearing down on the top of the angle. Then you would have to keep adjusting to keep the bottom roller tight.
With steel, you can apply a lot more preload on those skate bearings to help eliminate racking.
Some guys use aluminum, but given the choice, I know there is no question what I would use.

[Telly]

Wow it’s been a long time since I started this project, but it has been fun to do in my spare time.

Anyway I’ve got to the point now where i'm testing and already i've come into my first "problem". I’m using M6x1mm threaded rod, and well the rapids are koala bear slow ~100mm/min. I’m in need of a bigger pitch without going up in the diameter too much. I need some suggestions that can help me with this problem. I’m in the UK so any suggestion close to home would be good.

And another question, at the moment in running 7.5 degree steppers. Will 1.8 actually give a higher to feed speed? I know I will lose accuracy running a bigger pitch with 7.5's. But mini mill v1 will be born soon

Thanks, Matthew

[Kipper]

Originally Posted by Telly Wow it’s been a long time since I started this project, but it has been fun to do in my spare time. Anyway I’ve got to the point now where i'm testing and already i've come into my first "problem". I’m using M6x1mm threaded rod, and well the rapids are koala bear slow ~100mm/min. I’m in need of a bigger pitch without going up in the diameter too much. I need some suggestions that can help me with this problem. I’m in the UK so any suggestion close to home would be good. And another question, at the moment in running 7.5 degree steppers. Will 1.8 actually give a higher to feed speed? I know I will lose accuracy running a bigger pitch with 7.5's. But mini mill v1 will be born soon Thanks, Matthew

Hi Matthew, Missed your original post.....I'd have agreed with all the comments anyway I have a "Multimate" to build....it will cut foam rout MDF, draw, and cut vinyl....My choice for linear bearings is Ahrens design from cncrouterparts.com running on bright flat bar for the Y axis using 1.8 degree steppers, (7.5 is plain weird :naughty: ) run by drivers from Zapp in the UK not sure yet whether I'll be getting a litigation letter re the design copying.... You do realise this thread is worthless without pictures Here's my X axis brace.