Web Goblin cnc has begun

Thanks for the info. I'll try not to take offence at comments about the Myford, given the Super7 sitting in my workshop! In my defence, I did buy it long before the flood of far-East machines hit the markets and when industry was still using their hardware instead of selling it off cheap. I also built a vertical milling machine (the Dore-Westbury part-machined kit, for those that know it) on the S7. I agree, though, that those two machines are second-best to the Smart and Brown lathe and the Bridgeports I have been able to use on odd occasions, certainly in terms of rates of stock removal (and a Bantam and a Student as well, come to think of it) but they are very versatile (I cut the rack on the quill tube for the vertical mill on the S7) and I could afford them and at least I can get them both in my garage at the same time!

Always wanted to have a go at CNC, partly because of my electronics and computing background as well, so shall follow your progress with interest and in the knowledge that I am probably sufficiently equipped to do something useful even if slower than someone with access to more "commercial" facilities!

Good luck with the project,

Managed to get my Y-axis motor and bearing mount finished today.

Attachment 3685Attachment 3686

Also got it fitted to the back of the Y-axis beam although this position might change when the ballscrews arrive and are fitted. I have around 35mm adjustment to allow for tensioning of the timing belt.

Attachment 3687

Now I need to get the coupling bored out to the correct sizes for the motor shaft and spindle and get that fitted as well.

Regards

Ian

Hi all,
I havent managed to get much done at all in the last few weeks. I have a few jobs to do around the house and I have also been waiting on my ballscrews and nuts for around four weeks now.
Anyway the ballscrews arrived on Thursday and I got them unwrapped tonight. Now I`m totally hacked off to find that one of them is short by a long way. Its completely useless for my job. So I will have to speak to the supplier on Monday and get it sorted out.
Think I`ll go and take my frustration out on some baddies in Dead Space 2.

Ian

Right several weeks on now and guess what? My ballscrews turned up, well nearly. One of them is wrong again and I am going to have another two week wait, at least, to get a replacement.
I have managed to get some time in the workshop and have been able to get some more of my build done.
The Z axis is more or less complete and fitted to the machine as per the photos.

Attachment 3957Attachment 3953Attachment 3955Attachment 3954Attachment 3956Attachment 3952

I have the ballscrew for the Y axis and have fitted the ballnut and mounting nut and the end bearings and it is just sitting on top of the frame at the moment for me to get some measurements. Next job on Monday is to mill a spacer block of aluminium 95mm x 75mm x 16mm thick to go between the ballnut mount and the Z axis frame.
The Z axis took quite a bit of work to get right. After it was made and assembled I ended up with about 1.5mm of movement in the screw from end to end so it had to be taken apart and a new spacer ring made to suit. Once this was done and re-assembled there is no movement at all that I can see so I`m happy with it now. :dance:

Regards

Ian

Right then I have managed to get some more time on my build so here is an update.
Timing belt fitted for my Y axis drive and motor mount set up and tensioned.
Attachment 4006

I will eventually make a guard for it. I was thinking about clear perspex so that I can see any problems with the belt if they appear.

I have assembled the X axis ballscrews, nuts and mounts. Made up the spacer blocks and got them all fitted and set up.
Attachment 4009Attachment 4007Attachment 4008Attachment 4010Attachment 4011

Also got the couplings bored out and fitted and the motors mounted.
Attachment 4013Attachment 4012Attachment 4014


I managed to get a start on the control panel as well. Job for tomorrow is to remember where I stashed a short length of 75mm x 75mm alu angle to make the mounts for the limit switches and get them done. The limit switch brackets will be fitted with tee nuts in the extrusion slots so that I can adjust then to get the best working area from the machine.
Hopefully the next update will be a bit sooner than the last ones have been.

Ian

No flanges on the Y-axis pulley could cause problems, but I guess if the belt doesn't fall of then nothing to worry about. Why have you extended the motor shaft then put a pulley on the end? It seems an expensive way to do it. Surely the motor bearings are sufficient to take the belt tension, or was there another reason? The reason I mention it is you've now added the moment of inertia of that shaft to the system which will affect your acceleration a little.

Which motors are those? I'll be interested to see what feedrate you can get on the X-axis, and whether it's limited by screw whip or motor torque. I'd have been inclined to get 10mm pitch screws. With 20x5mm over that length you're limited to roughly 5000mm/min in theory. Twice that feedrate but less resolution (depending on pulleys) with 10mm pitch screws. Bit late now I guess.

What size is the box section you've used for the frame?

Looks like you're not far off running it now :smile:

Jonathan,
the y axis motor shaft was not long enough to got through the motor mount to take the pulley. I had looked at making a different mount for the motor but it was working out to be rather thin material to get the pulley fully on the shaft so I decided to go this way. I could have made it a bit shorter but I dont think it will make too much difference.
The pulleys I had at the time so went with them rather than buying new ones. If the belt does give problems and runs off I can always change them for castle ones later.
The motors are these ones from Zapp Automation : SY85STH156-4208. I ordered the 2-4 Axis Nema 34 kit 2 and went for the bigger motors. With these motors I should have plenty of torque to drive the machine around as it will be quite heavy when finished and I prefer to have the drive system over-rated a bit :whistling:
The frame extrusion is heavy walled 80mm x 80mm with 80mm x 40mm cross bars. I cant remember the exact size for the Y axis, around 340mm x 40mm I think and again the heavy walled section.

Quote:

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Originally Posted by Web Goblin

Jonathan,
the y axis motor shaft was not long enough to got through the motor mount to take the pulley. I had looked at making a different mount for the motor but it was working out to be rather thin material to get the pulley fully on the shaft ...

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I see, I got round that problem by making the mounts approximately this cross section:

Attachment 4015

It's thin in the middle, but the motor is supported mainly on the thicker bits. I started with a piece of aluminium angle - the little cutout in the corner was to accomodate the pulley flange.

Quote:

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Originally Posted by Web Goblin

The pulleys I had at the time so went with them rather than buying new ones. If the belt does give problems and runs off I can always change them for castle ones later.

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On my X axis I have a pulley with no flanges (the ones I made), and one with one flange. It's been fine so far so fingers crossed... You can always add your own flanges to the pulleys.

It looks like you've gone for the biggest motors you could find :lol:. What ratio are you using for the pulleys on the X-axis? Might be better off having a bigger pulley on the motor since there's plenty of torque. Then again if the critical speed of the screw limits the rapids anyway it wont make a difference.

I meant what size is the *steel* box section, as I'm going to make a frame soon for my router and wanted to get some ideas...

The pulley ratio is 1:1. They are 80 tooth pulleys if I remember correctly.
Sorry I misunderstood you on the frame:redface:. I have used 40 x 40 x 5mm angle for the base frame. As long as it is supported for longer lengths it will be fine. Simple adjustable feet made from large stainless steel nuts and bolts work well for levelling the whole machine.

Update time. I havent had much time again in the last few weeks but I am getting there slowly. I have managed to get some work done on the electrics now.
Attachment 4124Attachment 4123

I have fitted the limit switches and have most of the wiring in place with just some tidying to do. All motor have been connected up.

Attachment 4126Attachment 4127Attachment 4125

Drag chains and supports are fitted with wiring in place and the cables are glanded into the panel.
Attachment 4128
I need to finish off the internal panel wiring now and get it fitted then hopefully I can start getting things connected up.

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