1250 x 1250 cnc router (from scratch)

Minimum of 2 screws and I always use Lock thread on both shaft and screws. If you have trouble and can remove motors without needing to remove pulleys then get the Red compound that grips like shit to a blanket.! . . . . Just be warned you'll never remove the pulley again thou.!!

On ballscrews file a small Flat on shaft for one screw to land on.

Keys ways will stop pulley spinning but won't stop grub screw coming loose and pulley falling off.!

Really this isn't uncommon and for first few weeks/months it's good idea to keep going around machine checking screws etc until everything as settled down.

Now I'm answering no more questions until I've seen this bloody machine in one piece rather than load of aluminium parts and chips on my floor/bench which you've had now for best part of year. . Lol

Surely small flats on the shaft in the grub screw area should stop that. I always thought "two screws were better than one"!!! G.

I have two M4 hex grub screws 90 degrees apart on the pulley boss, one screw has a flat end that tightens onto a flat that was filed on the ball screw, the other has a point that digs into the shaft. One I've had the machine running a while and all is fine, some loctite will be put on the screw threads. Good quality screws and an allen key that is not worn means the hex socket does not round over.

Here are a few images from the build. I wont go into too much detail with text, but if anyone has any questions just let me know and i will give more detail.
I am really pleased with how it has turned out, considering it is the first machine i have designed and built. Huge thanks to everyone for the help!!!

Things i would do differently next time:
Not use cheap Omron relays! i had around 3 faulty ones which caused a head ache fault finding.
Get the dust extractor set up before surfacing the bed!!!
oversize the control box, as the wiring become a little messy and cramped
make the bed heigh adjustable
add rail adjustment to aid levelling
use epoxy to level the rails

Things still to do:
fit limit and home switches on all axis
finish the dust extraction system including dust shoe
loctite the pulley and grub screws onto the motors
calibrate the spindle speed

Putting the hours into the design was worth it. The assembly went well with the machined parts, the frame went together well to with only a couple of holes needing opening out. Slotting parts and adding adjustment in the design was beneficial for setting up and assembly.

It has taken near enough a year from design to working machine (working weekends and the occasional week night).

Anyway, enjoy the pics...

Attachment 12232Attachment 12233Attachment 12234Attachment 12235Attachment 12236Attachment 12237Attachment 12238Attachment 12239

Quote:

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Originally Posted by Danielroyal25

Still yet to post the build images... But Was cutting some oak today and all was going well until the grub screw holidng the pulley to the stepper motor on the z axis come loose almost scrapping the material!
what do most people use 1 grub screw or more, any locking compond, keyways?
i checked the others before starting the machine again and they were all loose. They are stainless steel m4 screws but being so small the Allen key just rounds off if they are done up too tight.

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Hi Daniel, try some blue lock-tite on the grub screws, also make sure your using the flat type screws not the pointed type, you could also use some thin brass sheet or shimming stock (steel, ebay?) to make some disks that live in between the screw and the shaft so as not to mark the shaft with the screw or if the pointed type, you could use a drill bit to make a matching divet on the shaft that the point of the screw will fit into.

Keyways are nice but for this you just need to support the grubscrew rather than the rotary motion, a little of the blue should sort it.

.Me

EDIT: Didn't notice there was a page 5 of this thread...it looks like you have enough ideas and the machine is coming along nicely!

That machine is looking very nice. Well done. G.

Quote:

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Originally Posted by Danielroyal25

Things i would do differently next time:
oversize the control box, as the wiring become a little messy and cramped

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Looks good Dan, how big or small is the is the control box you've used ? like you say it does look a bit cramped in there.
Mike

Thanks mike, it was 400 x 600 x 200. It weighs a ton!! I had to add an aluminium section on the bottom for cable entry etc which is around 40mm deep. This just about fitted all of the connectors an glands in. Would have a much larger box and add conduit / cable management in next time.
still new to mount it on the side of the machine and add vents on the top before it's completely finished.

Still looks very impressive to me Dan, looks as if I will have to keep my eye out for an 800 x 600 x 200 enclosure if it needs all that wiring and I will at some stage want to get 5 drivers in a case for my build. I noticed that on your Z axis which I have to looks fantastic very nice finish, that you've had both the parts machined to give clearance for the ball screw. Could you not have just packed out the plates where the rails and blocks are fitted and use a thinner plate ?
Mike

Bloody hell Dan when I gave you parts and said use some decent sized bolts to bolt Z axis together I didn't mean "Raw Bolts" . .:hysterical:

Looking good mate but now you know we need the matching video. .:thumsup:

Hi Mike, yes i could have used a thinner plate and packed the parts out but it just allowed all of the parts to be machined out of 1 sheet of material, saved ordering separate pieces.

Cheers Dean, will get some vids up soon. I was going for the industrial look with the bolts ha! i havent had much time to play around with it lately but as soon as i do i will get posting.

Opinions please. The pulley on all of the axis were bored out manually on a pillar drill (I know, stupid idea - I had no acess to a lathe) so they are are slightly off centre. They have 1 m4 grub screw in also clamping onto the flat of the motor shaft / ballscrew shaft.
after the slipping episode I am wondering whether to
a- have them rebored to a larger diameter and have an insert made up and add another grub screw for fixing
b- order some new pulleys that are pre machined at around £70
how much would optio a cost (if anyone is up for the job) or would anyone want to buy my old pulleys to modify and use.

i was just going to loctite them in place as is but if they align at worst case the belts tighten and loosen which isn't the best.

next question.. My dust extractor is linked via a relay for Mach to control. When in e-stop mode the relay is inactive. When the machine is reset the relay is active and switches the extractor on. How do I get the relay to be controlled via the g code command instead. The vfd run start stop is controlled this way and works fine but I have wired the extractor in a similar way and it's not working as expected.

Quote:

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Originally Posted by Danielroyal25

My dust extractor is linked via a relay for Mach to control. When in e-stop mode the relay is inactive. When the machine is reset the relay is active and switches the extractor on. How do I get the relay to be controlled via the g code command instead. The vfd run start stop is controlled this way and works fine but I have wired the extractor in a similar way and it's not working as expected.

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Some people use the relay built into the vfd to switch the extractor on and off, you will need to program it for this operation by consulting the manual.
You could use the Mist and Flood coolant outputs controlled by M7 and M8 in the G-code file. These are in the 'Ports & Pins / Spindle Setup' page of Mach3, you would then have to enable the corresponding output in 'Output Signals'.
This is just a similar arrangement to M3 and the relay you set up for the spindle.

New pulleys required Dan don't waste time with bushes etc not worth the hassle and would take just has long to make as boring new pulleys.

My Lathe is down at the moment else I'd offer to bore some new pulleys for you but sure some other kind sole might offer there services.!!

Regards The Vaccum then you want it controlled by an output then use M7 or M8 to turn it on and M9 off. To do this is just the same as with the spindle.
Select an output # in Mach's Ports n pins and set to the Pin number your using for the relay, either one built into BOB or separate controlled thru an output pin (or both).
Then in Spindle setup in ports n pins uncheck the "disable flood mist relays" box then enter the output # number (not pin number but OUTPUT number used) for either M7 or M8 depending on which M code your going to use in the G-code for turning on the vacuum. You can set a delay for it to come on if you want in the box next to Output #.

Thats all there is too it.!!

Ok, il try and answer what I can...

First off, I think you are referring to Chai. http://http://stores.ebay.co.uk/linearmotionbearings

Hi Lee, i have tried to contact the above address but have had no luck. is there some other way to contact Chai. has he a site i can order ballscrews, slides. etc? thasnks in advance Paulro.


p.s i'm just designing a cnc of similar size to this one and am at the drawing stage.

Hi Daniel, great build. i have steel ordered for a similar build and am curious to know the inside dimensions of your m/c. the travel of your x and y axis. i have allowed 1440 mm inside dimensions allowed for 1220 mm standard width of sheet.

Attachment 12995

i'm trying to minimize this dim so i can minimize the length of the gantry. i'm also curious about the distance from the spindle router collet face to the work table . as i say the steel is due in next Tuesday / Wednesday and i'll start cutting the frame members early next weekend so i have these last couple of days to refine and tweek the frame design. any input would be greatly appreciated. by the way ,it would be great to see videos of the m/c in action. !! cheers , Paulro.

Thanks Paulro,
X & Y both have 1250mm travel so will cut a full 4x4 sheet allowing 15mm a side. Just make sure that you allow for the width of the z axis, so that when the z is at either extreme of its travel it passes the board to make full use of the sheet and allow a little extra so that the z axis doesnt max out on its travel.
i think i left 150mm between the collet and top of the bed, i should have made the bed height adjustable really, but maybe next time....
i will try and get some vids up soon, i have been tweaking it lately and trial cutting projects so once it is all ok i will post some videos. let me know if you need any more info, all the best!