The birth of "Baby"

[Ali Kat]

Hello All,
Well it's time to stop lurking around the forums and bring you the news of "Baby's" arrival !!
The photo below is proof of my endevours to create a machine that will (hopefully)do what I tell it without backchat, tears or arguments!
As you will see it's not the biggest thing in the CNC world but it's my beautiful little baby and it's currently getting more attention than mere metal really deserves.
The Ali Baby evolved from a desire to replicate the amazing work that has been done by many of you guys out there but within the confines of a limited budget with additional help from my stockpile of "essential spares" (known to her who rules as Junk).
So here she is


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[Ali Kat]

Ebay has been a prime shopping area and has yielded Bosch aluminium offcuts, stepper motors, linear rails and other bits and bobs. When all of this was cast upon the bench some dimensions started to appear. The rails dictated the x axiz length (I didn't fancy cutting them and I didn't have any longer ones) at 575mm and the ballscrew assembly meant a moving table was the style that would make maximum use of both items. A width of 300mm was chosen because its a nice round figure.

So far I've:
1) milled the top of the 45 x 90 extrusions to accept the 12mm linear rails
2) drilled and tapped 46 off 3mm holes in 3/4 x 1/8 brass bar to act as long "T" nuts inside the extrusions for the rails
3) machined two aluminium end plates at 300mm x 100mm x 15mm
4) threaded the ends of four 10mm bright mild steel bars which run through the extrusions
5) fabricated a saddle plate that holds the ballscrew fixed bearing / motor mount.
6) bolted it all together to check for gremlins.

I set the whole thing up on the table of the miller and put a clock across the rails and was quite pleased to find .05mm variation on parallelism.
Just for fun I hooked up the motor to the controller and ran it back and forth a few times with no nasty noises. I must get on and make the sub table next

[Ali Kat]

Bosch offer a fancy (read expensive) screw which is used to connect to the end of their extrusions. It taps it's own thread and sounds like a good idea. Well I bought a small bag and tried it out but wasn't convinced that they would last so I decided to ensure that at least the end plates won't fall off.
In the pic below you will see the end of a 25" length of 10mm (i'm trying to be diplomatic / cosmopolitan with my measurment references) bright mild steel bar which has been threaded at both ends. This is passed through the two holes in each extrusion and the end plates fitted. Nyloc nuts pull everything together. The base is now extremely rigid!!!!

[Ali Kat]

It's all well and good having a nice strong x axis but what about the rest I hear you all say?
Well I never did take tech drawing or metal work at school so things tend to get done a bit different around here. I can use autocad to a degree and this helps when I want to draw out things and take measurements for machining purposes. However, basic design is usually done on bits of paper, backs of envelopes etc. So far we know it will have a moving table and the X, Y envelope should be about 300mm x 250mm. The Y axis will be mounted on a fixed gantry which attaches to the slots on the outer sides of the X axis extrusions. The bearing arrangement has not been finalised for Y axis yet as I'm considering THK type linear rails (I've got some odd sizes that I might be able to cobble something out of) or 10mm ground shafting as I have some phosphor bronze bushes of 10mm ID or perhaps a length of Igus twin shaft rail with plastic bushes.
Spindle will probably be a remote Dremel with a fex shaft and hand piece attached to the z axis. The Z axis is even further away from the manufacturing stage although I do have a nifty little micro slide made by Anorad Corp (USA). the only problem is the thread which is 40 TPI and may cause problems when mixed with metric ballscrews.
Controller will be either a NC Step product or SMC 1500 (both of German origin). I have both cards and they appear to work fine although the SMC uses it's own version of PCNC to control it.
Motors will be NEMA 23 size selected from my box of "previously owned electrical equipment"
Joking aside, I have spent a long time reading the successes and failures of the amateur CNC builder and have yearned to join the gang. This might be a bit "Heath Robinson" in concept, design and construction but I'm enjoying myself and would welcome any feedback from those that have been present at the birth.
Thanks to all for the encouragement to get me going.
N

[Mr.Chips]

Congratulations on your new addition. And thanks for the baby pictures. Keep them coming so we can keep track of her progress.

Hager

[DR-Motion]

Hi Ali Kat,

Congrats, The biggest hurdle faced by anyone in building a cnc machine is... overcoming the analysis paralysis and getting started.

Now that you're committed, your creative mind can now come up with all sorts of logical reasons as to why you should continue to spend excessive amounts of time, effort and money in its completion.

This will, of course, be frowned upon by "she who must be listened to."

But now you're a real man who has combined pieces of junk to create a real machine that can manipulate reality... you are the boss... so the first thing you must do when this masterpiece is completed is to machine something ornamental and personal with romantic engravings and such... and eventually she will talk to you again.

Seriously, your practical, modular approach will serve you well and I'm certain everyone will want to follow Ali Baby's growth.

regards Gary

[vacpress]

keep putting up pics! i really like your design so far..

dont stop the pictures!


we care.. really.

[High Seas]

Ali Kat - nice baby - give him/her/it a name yet?
No detailed 3d CAD drawings to start with either. Guess that then fits into the category of "sculpting?"
cheers - Jim

[Ali Kat]

Went to make the saddle / sub table today - you know, the piece that sits across the linear slide carriages. Well I got the mill set up and a piece of plate clamped down and off we went. Things were going well until I got greedy and took a bigger cut than i should have - yes, you guessed - I pushed the plate all over the place. So there I was with a beautiful face milled paper weight and a bad temper
Started again and this time it went well. Came to bolt it all up and it was still looking good. In fact I was quite pleased as I was doing all the referencing using the dials as the s/h DRO that I've ordered is still somewhere between me and it's sender!!! Holes all lined up between saddle and blocks, slide movement was good but then I decided to place the assembly back on the X-axis base. Uh oh, I appear to be out by a smidgen (UK expression for "small amount"). It seems like something needs a bit more tolerance. So off we went again machining the slots for the rails but this time using a 13mm cutter for the 12mm rails instead of a 12mm cutter. Lo and behold, it looks better - things actually fit now

Sorry there's no pics but I need to go and get cleaned up and hide any evidence of aluminium shavings from "HWMBO" (her who must be obeyed).
Got my 8-32 cap head screws today to mount the motor to the ballscrew - the sooner the whole world goes metric the better What on earth is a 8-32 when it's at home???
I have more bolts than a lightning storm but not a single one that would fit that mount so once again RS components profit margin rose as yours truly had to give in and pay up. I know, I know you guys in the States have cupboards full of them. So next time any of you come to Scotland to play golf or whatever then bring me a couple of hand fulls of assorted American attachment fixings!!
I'll try and post some more pics tomorrow if I get anywhere.
Cheers
N
PS Baby doesn't have a name yet - might need some help here.