Was about to get a toy- then I did some research...

[JAZZCNC]

That's the paradox I guess! I keep reading all the theory but as I haven't done this sort of a project before it's hard to tell what's essential and what's not. And as you rightly point out, doing the details/assembly properly will matter quite a bit for the end result (as it would for any project really), maybe even more than getting all the theory right ;)

Yes, Theory is great. However at the DIY level theory and reality often part company early on in the build process at which point reality often comes back and smacks you fully in the face.
I find if you have patience use Common sense along with doing the Duediligence like what you are doing now. Then provided you choose the right design for your needs and take care when building it that you will always end up with a machine to be proud of that won't disappoint.

Keep asking the questions like what you are doing and it will eventually make more sense, it won't make complete sense until you started the build, which at some point you will say "Aghh I get what Boyan was saying now." .!!

[JAZZCNC]

20mm is the plan, but not sure yet about going full hiwin or not...

If you want the best machine then you must bite the bullet and go with Profiled linear rails. If not then you are wasting your time worrying about things like COG or plate thickness because Boyan is 100% correct that the machine is only as good as the weakest link and round rails will by far be the weakest link no matter which axis you put them on.!

[Juranovich]

If you want the best machine then you must bite the bullet and go with Profiled linear rails. If not then you are wasting your time worrying about things like COG or plate thickness because Boyan is 100% correct that the machine is only as good as the weakest link and round rails will by far be the weakest link no matter which axis you put them on.!

Sorry for being a bit unclear, with "full hiwin" I meant as opposed to the "economy" type profiled rails. I've already been convinced to go profiled, although I expect to swear a few times more than had I gone with round rails...

[AndyUK]

I could also get creative and hang a 5kg weight from the spindle :D that should balance it up!

Someone hasn't yet gotten into the theory of their motor calcs yet! More mass on the Z axis means everything has more to accelerate! NIGHTMARE!!

Personally I think we should all just make them out of bamboo and some twine, powered by hamsters, and tamagotchis as control interfaces to just be done with it :)

[Juranovich]

Someone hasn't yet gotten into the theory of their motor calcs yet! More mass on the Z axis means everything has more to accelerate! NIGHTMARE!!

Personally I think we should all just make them out of bamboo and some twine, powered by hamsters, and tamagotchis as control interfaces to just be done with it :)

Interesting point! But you still have to considered the torque drop when hamsters get hungry and be sure to size the running wheel according to your choice of hamster, too small and your hamster will simply get stuck and start doing loops...Other than that you should be sweet

[JAZZCNC]

Interesting point! But you still have to considered the torque drop when hamsters get hungry and be sure to size the running wheel according to your choice of hamster, too small and your hamster will simply get stuck and start doing loops...Other than that you should be sweet

Arghh but you'll always struggle if you use hamsters, what you need with a heavy Z-axis is Guinea Pigs...

[Desertboy]

Welcome to the forum :)

Yeah... this is quite a time-sink (and potentially money-sink) of a hobby.... ;)

Based on your post title, I'm guessing you were thinking of grabbing one of those pre-made Chinese jobbies off ebay?

They get an awful lot of flack (from me too!) but I think they do actually have a place; as long as you're prepared for how pathetic their capabilities are, they're a reasonably inexpensive way of experiencing the CNC process and way of thinking, allowing you to start exploring what you might want out of a machine.

The Shapeokos of the world give the same lessons, but are more expensive to begin with, although probably allow a greater amount of time before you outgrow it.

My first CNC was a simple conversion of a 3D plotting tank (think 40x40x40 work area, but about as stiff as jelly). It taught me lots about GCode, CAD CAM and what I needed from a machine.

I built my CNC after building a Rep Rap it really helped get my head around how it all works.

Hiwin's and ballscrews but the core principles remain the same.

[Desertboy]

Sorry for being a bit unclear, with "full hiwin" I meant as opposed to the "economy" type profiled rails. I've already been convinced to go profiled, although I expect to swear a few times more than had I gone with round rails...

For a first time hobby builder I think clone rail is fine, BST automation on Alixpress are a good place to start.

If I was sinking thousands into a frame, decent spindle, etc I'd buy original and I already have original Hiwin on most my machine just one axis is clone.

I can tell you Hiwin's are definitely smoother than cheap clone rail before I fitted them but in practice on the router working you can't tell the difference. With 1610 ballscrews one step in 0.05mm so that's really what limits your resolution. Never consider microstepping actual resolution it's something very different. On a Mill clone rail probably makes a lot less sense.

If I was working it for cash 10 hours day I would definitely go original Hiwin.

[Desertboy]

If you want the best machine then you must bite the bullet and go with Profiled linear rails. If not then you are wasting your time worrying about things like COG or plate thickness because Boyan is 100% correct that the machine is only as good as the weakest link and round rails will by far be the weakest link no matter which axis you put them on.!

It was because of you and Boyan I never used the SBR 25 rail I have and bought Hiwin's and clone hiwin's.

One day I might use them for a plasma cutter, I did buy new bearings for them they do feel "nice" but very glad I went with rail instead.

One really annoying thing about them the mounts are 46mm apart.

[JAZZCNC]

For a first time hobby builder I think clone rail is fine, BST automation on Alixpress are a good place to start.

No that's wrong way to look at it. When buying from China most of the cost is the shipping, the difference between Hi-win and the clone isn't massive so it's not worth wasting shipping. Don't spoil a machine for just a few $$ more.