Scratch Build scratch build cnc table (plasma and router)

[mx0forever]

well well well

i just ran into a roadblock , and am looking för good ideas..

how sould i mount the threaded rod for the x, and y rails ....
the bit with the bearings is driving me crazy..

something like this would be ideal!


plan B that i could live with would be :


BUT the problem is, that i have been looking around for some time now and i CAN NOT find any bearing which can pivot and have a 10mm axle diameter , ( the closest i have found is 12mm )

i need some type of bearing that is sealed and allows the axle to be pivoted somewhat, to allow for construction error, ( because no cnc is 100% square, and if the bearing is not mounted exactly right then the axle will wedge stuck )

so does anybody have any good ideas on how to get around this?!

[morgansk]

Originally Posted by mx0forever

well well well

i just ran into a roadblock , and am looking för good ideas..

<snip>

BUT the problem is, that i have been looking around for some time now and i CAN NOT find any bearing which can pivot and have a 10mm axle diameter , ( the closest i have found is 12mm )

so does anybody have any good ideas on how to get around this?!

I'm not sure if this would work as I'm not sure whether the bearing you have shown is stationary (i.e. at the ends of the rods) or moving, but if it's the former then could you simply use some shims on a 12mm part to bring it down to size for your 10mm axles? Another alternative would be to make a plastic bush (out of some HDPE or Tufnol) - obviously this would wear a load quicker than steel but might get you out of a scrape...

[mx0forever]

Originally Posted by morgansk

I'm not sure if this would work as I'm not sure whether the bearing you have shown is stationary (i.e. at the ends of the rods) or moving, but if it's the former then could you simply use some shims on a 12mm part to bring it down to size for your 10mm axles? Another alternative would be to make a plastic bush (out of some HDPE or Tufnol) - obviously this would wear a load quicker than steel but might get you out of a scrape...

interesting idea.., but ofcorse i have tought about it aswell ...

and the shims seem to be as hard to find as the actual bearing ..,

if i understand you right then we are talking about something like this
( but on the inside of the bearing )

[Cheapskate]

I figured the rubber hose thing will fail. My first dremel had something similar to isolate the motor. -It failed, and failed, and f...
You need to use a drill press badly for the motor mounts.
...
I typed a bunch of stuff and deleted it because it sounded jibberish. You are on the right track with the set screws, but the coupling should be something like aluminum. I think the stepper shafts are exactly 1/4". Somewhere in that mess called the GwassGween log, I made a coupling for my rotary table...
Edit: found it. post 437

Those holes in the end fit rod stock, which links to the other coupling and gives you a little play if your alignment is off.

Anyway, probably rambling crazy talk. I do that.
Oh, and McMaster Carr should have any size bushing you might need.

[shinji2k]

I've been wanting to build a cnc router for a couple years now, and this is the most... unique... one I've come across. But if you can get it to work, it'll be badass. I'll be keeping an eye on this.

[mx0forever]

well i finally cracked the z-axis ..

i am one lucky *******.., hehe
i know a guy who knows a guy, who has a neighbor, who works at the right place..
( you see when a big industry does some changes to there production line , they just order up a big pile of parts which they beleve are needed.., sometimes some stuff is left over ...)



this is the stuff i have layng around , bearings, rodends ect.., stuff that when needed is crusial otherwise just in the way..

after some digging i came up with this solution.., :
one hard rubber bushing with metal sleeves, ( inner diameter 10mm)
pressed into a bigger bearing :



whilst looking through the stuff i found something amazing ..



but as usual it was too good to be true..
one side was the right diameter ( 8mm for the stepper motor)
but the other side...



one sacrificial old M12 bolt :



and 2 spotwelds later:



this is now i beleve the 9th or 10th try,..
and as usual i stresstested it with my trusty weight (40kg), i didnt get a good picture of it , but worked like a charm.., i got some basic g-code running and it ran without any problems for adlest 30min , even felt comfortable enough to turn my back at it and do some cleanup..

the machine is not set up completely yet so there was some flexing .., i need to get all the rails goof and tight before i start milling..

the problem im mostly facing at the moment is how to get my weldings centerd.., anybody have any good advice here?

[mx0forever]

Originally Posted by shinji2k

I've been wanting to build a cnc router for a couple years now, and this is the most... unique... one I've come across. But if you can get it to work, it'll be badass. I'll be keeping an eye on this.

Nice!
unique, as in good ?
( hopefully ill get some basic cnc action in the middle of next week )

[morgansk]

Looks like you have that drive problem sorted - and I see you have a flexible drive on the shaft there which should work a treat. It's great having friends who can find stuff for you! Sadly none of mine yet have found the £1M that I'm after.

[kelmannen]

well, haven't seen this log until now! looks fantastic!

hmmm.. can you please share the seller on ebay? and if you don't mind, also the prise
i've been looking at different kinds of packages on ebay but this one seems kinda complete
Me and my brother has been planning on building a cnc for some time now, might soon get to the point where we need parts :P

ps, you do have a little crowded garage eeh?
ps #2, which conutry? nordic i think?

[mx0forever]

Originally Posted by morgansk

Looks like you have that drive problem sorted - and I see you have a flexible drive on the shaft there which should work a treat. It's great having friends who can find stuff for you! Sadly none of mine yet have found the £1M that I'm after.

Haha!, was it a bunch of 100£ bills wrapped in a paper band ?
because i found the band ..

about the motorshaft, its ok but not perfect.., ill take a drive to the city soon to hopefully find the RIGHT motor coupling.., ( im thinking about 8mm center hole , so i can enlarge one side and thread it to fit the threaded rod.., so everything will be CENTERD!!, im having lots of problems with getting stuff centerd ..

Originally Posted by kelmannen

kelmannen, you got mail

[sixfootsideburns]

I would highly recommend you take this build over to cnczone. The group over there has a ton of build knowledge and can provide you with some awesome feedback.

I'd be a little worried about mounting your motor up like that though, when you go to cut material I think you'll see quite a bit of resonance and you may break that coupling on your z-axis.

[Cheapskate]

Tell your buddy you need more couplings. Those are perfect.

[mx0forever]

Originally Posted by sixfootsideburns

I would highly recommend you take this build over to cnczone. The group over there has a ton of build knowledge and can provide you with some awesome feedback.

I'd be a little worried about mounting your motor up like that though, when you go to cut material I think you'll see quite a bit of resonance and you may break that coupling on your z-axis.

i do respect your opinion at the highest level, but no..

about the z-axix coupling could you elaborate a bit more?

Originally Posted by Cheapskate

Tell your buddy you need more couplings. Those are perfect.

nja i believe he retired from the buisness ..
and those couplings were damn good but not perfect..

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broke 10-000+ views today ,

time for an update.., its been a few days..,
and i have been buzy with school ( mostly )
and been getting a-hold of some parts , and some stuff from ebay has arrived aswell

as i just mentioned the coupling i had was not perfect..,
so i got a hold of something just a bit better:



these are exactly the same as the one i had exept the axle hole is really small.., the point is to machine it out yourself to the exact size.., ( i i payd for 4 coupling and the other 2 are comping by mail soon.. )

some machining later:



one side is threaded , so i can just thread it on the threaded rod and lock it down..,

this is how i assemble the bearings for the threaded rods
clean it a bit





and give it a little squeeze



the very first test of the y rail





and here is the latest shopping:



as you see there will be some "computer" modding aswell



the stop family in the upper left corner

a bit off topic:
this is from my other project , anybody want to hazard a guess , what it is ?

[Pranja]

Brilliant. Can you post pics of whole CNC?

For question-is that carbon fiber tube for subwoofer box?

[RichCreedy]

are you building some sort of turbine?

[mx0forever]

Originally Posted by Pranja

Brilliant. Can you post pics of whole CNC?

For question-is that carbon fiber tube for subwoofer box?

ok big pic will come in the coming days ( just so much junk on it at the moment )

For question, damn close , yet no cigar..

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ok just went over some of the details of the build in my head ., and one small problem is bothering me..

cable management ..
now this has to be the best forum to ask this..

basically i need good ideas on how to manage cables
requirements:
simple , homemade , and most important flexibel.., ( meaning it if i start with putting in one, cable, and after some time i need to put in 7 more.., it has to be able to handle this )

this is the basic idea .. ( but as many know.., these are useless )

[kelmannen]

tnx mx0forever for the mail fantastic progress Really want to se this beast alive!

If it's an axle you trying to get welded straight i have a tip on how to make a axle jig

Use an ordinary kkr or angle iron or somet straight iron as long as it ~~trueish.

Stack 4x flatirons on each other and bore the holes trought them at the same time (so they have the holes at exactly same place and ofc same radius as your bearing rod)

Push the rods trought the holes, secure the bearing at the right places(if it's a tight fit you don't need to overdo it, they will rotate very slowly....)

Weld/bolt the flatirons to the base with the rods in place (a LOT easier to get it straight from the beginning!) place the 2 pieces on top, put a little weld, rotate, weld, rotate, weld, and so on.

This is a very general jig that can be used from very small axles to very large axles, only depends on the size/distance of the rollers/bearings

Edit: i made this model in sketchup, here is the link to 3d warehouse if someone want's it

[kelmannen]

Originally Posted by mx0forever

cut
/cut
help with cable management??

put a bunch of strap on it! (preferably with rivets!)

[sixfootsideburns]

Originally Posted by mx0forever

i do respect your opinion at the highest level, but no..

about the z-axix coupling could you elaborate a bit more?

Well its your project and you will do what you want with it I will tell you though, they are probably one of the most knowledgable and informative communities on the web with regards to CNC.

As for the z-axis. As I'm sure you are aware, rigidity is one of the biggest goals of any CNC design, be it lathe, mill or router. When you start cutting material the forces of your tool on your material are going to torque your z-axis (again as I'm sure you know). When it torques, its going to stress the whole gantry assembly, tighten up any "wiggles" and the weakest location is going to resonate. From all the pictures you have show that motor mount looks like it is the weakest point by a long shot and I would be concerned that the resonance transmited to the mount along with any vibration from the motor operating would be enough to cause problems.

However, I don't know your full design or your final plan let alone have any idea what kind of repeatability or accuracy you are hoping for. But I do know that I've done a fair amount of research into the topic of CNC router designs and stiffness is nearly always a concern.

So... you are of course welcome to do whatever you want with that information But I know the frusration of completing a project just to find out you missed something, so I figured I would give you my .02

[mx0forever]

Originally Posted by sixfootsideburns

Well its your project and you will do what you want with it I will tell you though, they are probably one of the most knowledgable and informative communities on the web with regards to CNC.

As for the z-axis. As I'm sure you are aware, rigidity is one of the biggest goals of any CNC design, be it lathe, mill or router. When you start cutting material the forces of your tool on your material are going to torque your z-axis (again as I'm sure you know). When it torques, its going to stress the whole gantry assembly, tighten up any "wiggles" and the weakest location is going to resonate. From all the pictures you have show that motor mount looks like it is the weakest point by a long shot and I would be concerned that the resonance transmited to the mount along with any vibration from the motor operating would be enough to cause problems.

However, I don't know your full design or your final plan let alone have any idea what kind of repeatability or accuracy you are hoping for. But I do know that I've done a fair amount of research into the topic of CNC router designs and stiffness is nearly always a concern.

So... you are of course welcome to do whatever you want with that information But I know the frusration of completing a project just to find out you missed something, so I figured I would give you my .02

now thats good insight! thank you!

well the plan is that sometime in the future to upgrade to a belt frive from the motor to the threaded rod.., ( so i can use different sized pulleys.., ).., but this motor mount i have right now is highly temporary., i aim to get the machine running so i can cnc cut better motor mounts.,

as far as i know , the best way to dissapate the resonance of milling is to basically build it overkill, with HEAVY materials.., ( kind of what im doing)
example, big $$$ mill, is basically a big cast iron lump , there is a reason for this..,

and with as much as possible of my machine being homemade, leads to easy design changes later on..,