[mikeschn]

I started building my DIY Cheap CNC machine today. I figured I'd better start another thread, cause the first one was already over 4 pages long.

Here's what my CAD model finally ended up looking like...

Mike...

[mikeschn]

And here's the first picture of my construction...

Mike...

[balsaman]

Good job. Keep it up. Paint it before final assembly. Makes it look way better and resists water/oil. A drop of oil on MDF makes a stain 4" in diameter.

Gives it a very sturdy look too.

Eric

[DDM]

It looks like a great start, What did you use for your linear rods if you don't mind me asking?

[mikeschn]

The X-axis is 3/4 x 36" Thompson Hardened Steel shaft from McMaster Carr. ~$35

Y will be 1/2 x 24 and Z will be 1/2 x 12

[oz9ny]

Originally posted by balsaman
Good job. Keep it up. Paint it before final assembly. Makes it look way better and resists water/oil. A drop of oil on MDF makes a stain 4" in diameter.

Gives it a very sturdy look too.

Eric

Always a dillemma :-)

When building something you want to see some results in a hurry Then finish can be done afterwards, if ever?

/Niels

[xairflyer]

Great to see another MDF machine in the making.

What are you using for bearings on your slide's, your picture has got me thinking !

[mikeschn]

Hey Xairflyer,

I used ceramic coated linear bearings, press fit into the MDF!

Mike...

[dlenox]

Mike,

Interested in the ceramic bearings, where did you get them
and for how much?

Great job so far! I will be starting a small machine myself in
a week or so.

[mikeschn]

I got them from McMaster Carr. The 3/4" ones were 11.25 and the 1/2" ones were 9.69.

Mike...

Originally posted by dlenox
Interested in the ceramic bearings, where did you get them
and for how much?

[balsaman]

Well,

Painting generally get's done before you finish or never... that is why I encourage peole to do it before...

Eric

[Hobbiest]

The Balsaman speaks the truth! This stuff stains like crazy. You think oil is bad though? Try wax! You'll never get that off without destroying the wood!

[steveald]

If your unsealed MDF machine isn't big enough, just add water

Steve

[xairflyer]

I thought that was what you had used, I have been looking at similar types from pacific bearing they call them simplicity bearings, and they seem far supereor to normal linear ball bearings in load carrying and life span. A lot cheaper too.

I can source shaft at fairly reasonable prices, but the price of the aluminium housings for the bearings put me off for a budget machine.
Concidered making my own, but a lot of work is required to get them accurate.

Fitting them into the mdf, has really got me thinking now !
You can get a self aligning version, which has the centre of the OD of the bearing slightly larger, so it "rocks" slightly in its housing, I think these would work great in my 1" mdf.

[mikeschn]

xairflyer,

Building this machine gives me a new appreciation for what is involved in building a precise machine!

I assembled my Y axis last night, and it binds up. Won't move at all.

I'm thinking the bearings are not perpendicular to the shafts, and being press fit doesn't help.

So I am going to recut the two bridge side pieces tonight. (I pretty much messed em up getting the bearings out!!!)

I was wondering how to make it self aligning, and your message gave me the answer. The hole for the bearing will be a slip fit, except for the last 1/4", which will be a press fit.



Mike...

[jimbo]

whats wrong with a wood version of a bearing block that clamps to the bearing. if done with a drill press and table saw it comes out pretty accurate. i am using this method for mine. it allows for some adjustment during assembly.

i am wondering in the long term, how well mdf will retain its fit on the bearing using the slip fit you described.

[xairflyer]

I know exactly what you mean, I spent hours last night setting up my Y axis rails and making the carriage, dos'nt seem right to be trying to make a block of wood 58.8mm !!!
Luckily I have a mill and was able to mill it perfectly square.
MDF mills great !


What about making the hole slightly larger and fitting "O" rings to the natural groves in the bearings ?

This seems to be used with the self aligning versions.

[Mr.Chips]

Inventit isuggestion would take care of holding the bearing tightly, if it wasn't centered exactly, the holes could be enlarged for alignment then the mount could be pinned to the frame to prevent movement.

I’m thinking the rail bearings have to be rigidly mounted, if a O ring were used, then during the cutting process there’s a lot of force and it would crush the O ring and make the cut inaccurate.

I'm thinking this might be used on the rail bearings also take three pieces of MDF and stack drill, the end pieces would be like Inventit's suggestion the the center one without the clamp. bolt together at the bottom only let the top float free for the clamping action. Will post drawing later.

Here’s design from Anoel for a clamp able bearing mount.
Here's a pic of the bearing block that I used on the Y axis of my big machine. Is' just made from 1/2" PVC and Clamps around the bearing. The Skate bearing fit nice and tight and after clamping, doesn't slip .

[Mr.Chips]

Here's a rough front and side view of a rail bearing. The dia. would be the OD of your rail bearings. It would bolt to the axis frame, mount holes not shown.

The "stack" could be as long as your bearings, and just clamped on the ends.

Make the stack on the original mach by hand, then cut a better stack when you get the it running.

This drawing is based on a bearing design from Anoel.

[Hobbiest]

If you want to make wodden pillow blocks, drill the holes first, then cut the outer dimensions to be equal on all blocks. Get some .001 shims for alignment from the gantry. Or just use a conduit clamp! Get the double mount ones (two ears) that they use to mount EMT. elongate the holes and use nuts and bolts so you can adjust. Any bearing that has no moving parts is called a simple bearings. That is the actual generic term, as far as I have found.